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- 摘要：Camellia granthamiana is a plant species endemic to China with a small population， and is listed as a key protected species in Guangdong Province. Studies on its community structure are of great significance for its conservation and management. In this research， plot surveys were conducted in five C. granthamiana communities distributed in Guangdong Province， and the survival status of the species was analyzed from three dimensions： Community structure， species diversity， and phylogenetic structure. The results showed that： （1） Among the five communities， the age structure of C. granthamiana populations was of the growing type. In Baixi of Zijin County （BX-1， BX-2） and Heishiding （HSD-1）， C. granthamiana was the dominant species in the lower and middle layers of the arbor layer， with sound population regeneration； whereas in the community of Mount Qiniangshan in Shenzhen （QNS-1， QNS-2）， the species had a very small population size and existed mainly as an associated species. （2） QNS-1 had the highest species richness and evenness， with the most stable community structure； by contrast， BX-1 had a high dominance of C. granthamiana but a relatively low species evenness. （3） The deep-level phylogenetic structure of QNS-1 and QNS-2 tended to be clustered， indicating that habitat filtering played a leading role in community assembly. On the other hand， the deep-level phylogenetic structure of BX-1， BX-2 and HSD-1 showed a divergent pattern， suggesting that competitive exclusion was the dominant process in community assembly. For the shallow-level phylogenetic structure， the plots QNS-2， BX-1 and BX-2 exhibited a clustered distribution， which reflected the filtering effect of environmental conditions on the composition of closely related species in the community； while the plots QNS-1 and HSD-1 showed a divergent pattern， indicating that competitive exclusion mainly acted among closely related species. （4） The plot QNS-1 is located in the transition zone between the southern subtropical and northern tropical zones， which had the highest phylogenetic diversity， and the most complex species composition. This study reveals that the endangered status of C. granthamiana is the combined result of its narrow geographic distribution， fragile population regeneration ability， human interference and environmental screening. In summary， this study systematically clarifies the structure and construction mechanisms of the natural communities of C. granthamiana based on the data of community ecology and phylogenetics， providing a theoretical basis for the implementation of in-situ conservation and population restoration.关键词：Camellia granthamiana;community structure;species diversity;phylogenetic diversity12|34|0更新时间：2026-05-25
- 摘要：Polycyclic aromatic hydrocarbons （PAHs） are a class of persistent organic pollutants widely distributed in the air， water and soil. They are teratogenic， carcinogenic and mutagenic， posing a serious threat to the safety of aquatic ecosystems. As primary producers in aquatic ecosystems， algal photosynthetic systems are sensitive targets of PAHs toxicity， but the mechanisms of PAHs-induced damage and transcriptional regulation on algal photosynthetic systems remain unclear. In this study， the model freshwater green alga Raphidocelis subcapitata was used as the research object， combining chlorophyll fluorescence imaging technology and transcriptomic analysis to explore the effects of PAHs on the algal photosynthetic system and its regulatory mechanism. The results showed that the inhibitory effect of benzo［a］pyrene on the maximum photochemical efficiency of R. subcapitata was generally weaker than that of phenanthrene （PHE） and pyrene （PYR）. The electron transport rate of algae in the PHE and PYR treatment groups decreased to 43% and 49% of the control group， respectively， while PAHs exposure had little effect on the non-photochemical quenching coefficient of algae. The expression of five key genes in the algal photosynthetic system （cabII-1， LHCA4， LHCA5， PsbP and PsAN） was time-dependent， showing a significant upward trend on days 3 to 5 of exposure and decreasing on day 7. With the extension of exposure time， the transcriptional regulation mechanism of the algal photosynthetic system gradually became imbalanced， eventually leading to continuous damage to photosynthetic function. This study clarified the damage mechanism and transcriptional regulation characteristics of PAHs on the algal photosynthetic system at the physiological and molecular levels， providing a theoretical reference for the ecotoxicological study of PAHs and the assessment of aquatic ecological risks.关键词：polycyclic aromatic hydrocarbons;Raphidocelis subcapitata;transcriptomics;photosynthesis5|37|0更新时间：2026-05-25
- 摘要：As a significant pathogen of marine fish， Vibrio harveyi has caused huge economic losses of marine economic fish farming industry in China. In this study， we investigated the changes of intestinal microbial community structure and immune responses in Epinephelus coioides during V. harveyi infection. Results showed that V. harveyi infection altered the intestinal microbial community structure： the relative abundance of Proteobacteria decreased from 79.06% to 56.22%， while Firmicutes increased from 5.46% to 12.90%， Bacteroidetes changed from 2.78% to 9.80% and Actinobacteria changed from 1.97% to 2.47%， indicating that the emergence or increased relative abundance of potential pathogens such as Pseudoalteromonas， and decreased proportions of beneficial bacteria such as Psychrobacter. Meanwhile， differentially expressed genes enriched in GO terms and metabolic pathways related to immunity and antioxidant defense， including lysozyme activity， peptidoglycan muralytic activity， oxidoreductase activity and glutathione metabolism. These findings reveal that pathogenic bacteria can directly influence the structure of intestinal microbial community structure， as well as the extent of changes in host immune organs and key immune genes. Therefore， it is important to protect the intestinal health of farmed fish for disease prevention.关键词：Vibrio harveyi;Epinephelus coioides;gut microbiome;differentially expressed genes4|52|0更新时间：2026-05-25
- 摘要：Twenty-five hybrids as andrographolide（AG） molecular structural form similaritity analogues AG-Sn（n=1-25） were designed and synthesized，where the flexible trans-decahydronaphthalene with exocyclic double bond moiety of AG was replaced by rigid naphthalene ring，and α，β-unsaturated-γ-butyrolactone was replaced by flexible linear α，β-unsaturated amide. The total yield of these 11-step reactions was 29%-35%. All hybrids are reported here for the first time. The experimental results revealed that the α，β-unsaturated amide scaffold significantly influences the anticancer activity of these hybrids. Just the same as AG，hybrids with rigidity，high steric hindrance，and high-tension substituents on the nitrogen atom of amide bond including AG-S2，AG-S4，AG-S5，AG-S6，AG-S7，and AG-S16 were demonstrated with good antitumor activity against rat glioma cells（C6），human liver cancer cells（HepG-2），human colon adenocarcinoma cells（Caco2），human malignant melanoma cells（A-375），and human breast cancer cells（MDA-MB-231），exhibiting broad-spectrum anticancer activity. Among them，compound AG-S2 exhibits the most prominent anticancer activity against C6，with an IC50 value of（0.9±0.2） μmol/L，which is 10-fold more active than that of AG. All these six compounds were indicated with higher inhibitory activity on HepG-2 cells than that of AG. The structure-activity relationship（SAR） study reveals that hybrids with α，β-unsaturated amide bonds with double substitutions on nitrogen atom generally exhibit better anticancer activity. All the above results indicate that molecular structural form similarity is an effective way to search for new drug candidates.关键词：molecular structural form similarity;andrographolide;antitumor;drug design;drug synthesis13|33|0更新时间：2026-05-25
- 摘要：The existence of solutions for a class of superlinear second-order discrete Neumann boundary value problems of the form
- 摘要：The existence and uniqueness of solutions，as well as the existence of global attractors and strong global attractors are investigated for a class of Kirchhoff-type beam equations with degenerate nonlocal strong damping. Firstly， we establish the existence and uniqueness of weak solutions by employing the Faedo-Galerkin approximation along with interpolation inequalities. Secondly， by constructing a bounded absorbing set，we establish the asymptotic compactness of the solution semigroup， and thereby obtain the existence of a global attractor in the topological space
- 摘要：To address the lagging nature of traditional academic early-warning systems and the homogenization of support interventions， this study innovatively integrates ensemble learning with causal inference algorithms. An AdaBoost model， validated on data from 2 003 students， was employed to achieve precise stratification and real-time monitoring of academic risk. A causal forest model was then used to quantify the net effects of interventions， enabling the development of multidimensional personalized support strategies.Three types of higher education institutions at different tiers were selected， with each type including 50 students in the experimental group （AI-based early warning and personalized support） and 50 students in the control group （traditional early warning and conventional support）. Following two academic years of intervention and longitudinal tracking， the results showed that the experimental group achieved an average GPA increase of 35.70%， significantly higher than the 19.40% observed in the control group. Improvements in learning behavior compliance rates and academic adaptability scale scores were also significantly greater in the experimental group （
- 摘要：Coastal environmental change resulting from global climate variability has significant implications for regional development. Hailing Bay， located in the northern South China Sea， preserves a continuous Holocene sedimentary archive， making it ideal for reconstructing paleoenvironmental evolution. This study examined the offshore HLZZ08 core and established a chronological framework using radiocarbon （14C） and optically stimulated luminescence dating. Grain‑size parameters were used to build sedimentary sequences. End‑member modeling， grain‑size standard deviation analysis， and principal component analysis were applied to explore the relationship between grain‑size variability and regional environmental change. The sediment grain size distributions in core HLZZ08 are primarily unimodal to bimodal， indicating multi‑stage shifts in depositional dynamics. The fine‑grained components reflect variations in summer monsoon intensity and fluvial discharge， whereas the coarse‑grained fractions correspond to stronger fluvial and marine hydrodynamic conditions during lower sea‑level periods. Grain‑size variations reveal a strengthening summer monsoon in the early Holocene， followed by a progressive weakening in the mid‑Holocene， with depositional dynamics primarily controlled by monsoon intensity and sea‑level fluctuations. Over the past 2000 years， the sedimentary evolution shifted from being monsoon‑dominated to sea‑level‑controlled. During this period， fine particles remained sensitive to summer monsoon variability， while coarse particles primarily tracked sea‑level changes. Concurrently， grain‑size fluctuations over the last millennium have also shown a degree of synchrony with regional indicators of human activity. These findings provide new insights into Holocene environment-human interactions in Hailing Bay and advance paleoenvironmental research in the northern South China Sea.关键词：Holocene;grain size analysis;Paleoenvironment;Hailing Bay;South China Sea41|48|0更新时间：2026-05-20
- 摘要：The H-κ stacking method， commonly used to estimate crustal thickness and velocity ratio from receiver functions， has recently been extended to extract structural parameters of sedimentary layers. However， in ancient， high-velocity sedimentary strata， the H-κ spectrum is often contaminated by a continuous high-amplitude strip near zero depth caused by the direct P-wave. This renders the traditional criterion-selecting parameters based on the global maximum stacking amplitude-invalid， making it difficult to identify the sedimentary basement interface. To address this issue， we propose an optimized H-κ scanning method based on the flood-fill algorithm. The method treats the H-κ spectrum as a two-dimensional energy terrain and analyzes its connectivity structure. It automatically identifies and removes the non-physical high-amplitude region connected to the zero-depth boundary， thereby determining the optimal H-κ parameters within a topologically closed energy basin. This approach requires no additional velocity model or empirical depth threshold and preserves the original physical framework of the H-κ method. Synthetic tests and feild data applications from a short-period dense array on the western margin of the Ordos Block demonstrate that the improved method effectively suppresses interference from the zero-depth spurious peak and accurately identifies sedimentary thickness and velocity ratio.关键词：sedimentary thickness;receiver function;H-κ scanning;flood-fill algorithm;western margin of the Ordos Block12|30|0更新时间：2026-05-15
- 摘要：This paper constructs a magnetic coupling cantilever beam system with bistable characteristics，and conducts a systematic study on its vibration resonance properties from both theoretical analysis and experiment. Firstly，a nonlinear dynamic model of the bistable cantilever beam system is established，and the analytical expression of the system's low-frequency response is derived using the fast-slow variable separation method. This theoretically reveals the intrinsic mechanism by which the high-frequency excitation modulates the slow variable to equivalent natural frequency and induces vibration resonance. Subsequently，a magnetic coupling bistable cantilever beam experimental platform is built，and experimental research is carried out under dual-frequency excitation conditions. The experimental results clearly observe the vibration resonance phenomenon，and its variation pattern is in good consistency with the theoretical analysis results. This paper validates the realizability of vibration resonance in macroscopic structures from the mechanical experiment perspective，and provides a practical research idea for weak signal amplification and detection based on the nonlinear dynamic mechanism.关键词：bistable system;vibration resonance;piezoelectric cantilever beam;weak signal amplification17|34|0更新时间：2026-05-15
- 摘要：Based on the theory of fractional-order viscoelastic mechanics and classical elements， a constitutive model has been established that can accurately characterize the creep and dynamic mechanical behavior of polymers. In response to the damage evolution characteristics during the material rheological process， a damage variable considering time effects is introduced to construct a damage-involved fractional-order constitutive relationship， effectively representing the mechanical response of the material in complex nonlinear processes such as stress relaxation and accelerated creep. To verify the reliability of the model， a dynamic mechanical analysis model was built based on the fractional-order Poynting-Thomson model， and comparative validation was conducted through dynamic mechanical experiments. The results show that the hysteresis loop curves fitted by the model are highly consistent with the experimental data， demonstrating the effectiveness of fractional derivatives in describing the dynamic mechanical properties of polymers.关键词：viscoelastic materials;fractional constitutive model;creep damage;relaxation;dynamic mechanical behavior14|28|0更新时间：2026-05-15
- 摘要：With the advantages of high power density， galvanic isolation， and soft-switching capability， the dual-active-bridge （DAB） DC-DC converter has been widely used in modern DC microgrids and renewable-energy systems. However， when a DAB converter supplies a constant power load （CPL）， the load exhibits negative incremental impedance， which can drive the system poles into the right-half plane， thereby causing oscillations and instability. To address this issue， this paper proposes an active-damping-based improved active disturbance rejection control strategy， developed from the reduced-order averaged model of the DAB converter and the equivalent CPL model. A shunt virtual admittance is designed at the DAB output to actively compensate the negative impedance introduced by the CPL. On this basis， the linear extended state observer （LESO） and the linear active disturbance rejection control （LADRC） structure are reconfigured to simultaneously mitigate the adverse effects of negative impedance and enhance robustness. Experimental results show that， compared with conventional PI control and standard LADRC， the proposed method effectively suppresses output-voltage oscillations， shortens the settling time， and improves system stability.关键词：dual active bridge;constant power load;active damping;active disturbance rejection control11|32|0更新时间：2026-05-15
- 摘要：This paper proposes a domain adaptation detection framework based on self-supervised visual representations， integrating general object detection with prototype library matching techniques. By leveraging the pre-trained features of DINOv3 for matching and screening， the proposed method can localize and distinguish target vehicles under few-shot conditions without the need for fine-tuning. First， a data augmentation front-end module based on multi-view synthesis is constructed to generate multi-angle samples. This aligns with overhead surveillance scenes， compensating for viewpoint deficiency in cross-domain settings. Subsequently， an inter-class clustering and prototype matching method is designed. By mining data modalities via clustering algorithms， a real-world prototype library encompassing various morphologies is constructed to address the issue of large intra-class variations. Building upon this， a joint global and local representation is introduced， which integrates semantic and textural details from different network layers to achieve fine-grained discrimination of target vehicles. Experimental results demonstrate that under few-shot conditions， the proposed method effectively overcomes the degradation in detection performance caused by viewpoint domain shift. Compared with traditional approaches， it improves the detection recall rate and significantly reduces false positives triggered by non-target vehicles， validating the effectiveness and robustness of the proposed domain adaptation framework in special vehicle monitoring scenarios..关键词：special transport vehicle;self-supervised visual model;domain adaptive detection8|21|0更新时间：2026-05-15
- 摘要：Plague and cholera frequently occurred in Northeast-North China during the republic period of China， representing one of the most severe public health crises of the period. Using an epidemic database （1912-1949） and concurrent meteorological grid data， this study employed Mann-Kendall mutation tests and spatial auto-correlation analysis to compare the spatiotemporal distributions of the two diseases and to identify regional differentiation patterns in their climatic response mechanisms. The results showed that： 1） Temporally， both diseases exhibited consistent peak periods during 1917-1921， 1928-1935， and 1943-1947. 2） Their seasonal distributions were opposed： plague peaked in winter （34.9%）， whereas cholera was concentrated in summer and autumn （97.7%）. 3） Spatially， plague hotspots formed a high-value belt in eastern-central Inner Mongolia， dominated by natural foci attributes； cholera hotspots clustered in the Beijing-Tianjin urban agglomeration and the Northeast railway corridor， significantly influenced by transportation networks， population density， and water sanitation conditions. 4） Climatic responses showed that， plague was negatively correlated with temperature （65.69% of the study area） and precipitation （51.92%）， favoring cold-dry conditions. Conversely， cholera was positively correlated with temperature （64.89%） and precipitation （63.92%）， favoring warm-humid conditions. During years of abrupt climate change， plague was more sensitive to temperature shifts， whereas cholera was more sensitive to precipitation changes， revealing a marked differentiation in their climatic responses. This study provides historical references for differentiated risk management in modern epidemic prevention.关键词：plague;cholera;meteorological elements;the republic period of China;Northeast-North China13|16|0更新时间：2026-05-15
- 摘要：Understanding historical and future water resources dynamics is essential for sustainable basin management. Using the Budyko equation and CMIP6 multi-model data， a total differential approach was applied to quantify the contributions of precipitation and potential evapotranspiration to water resource dynamics across China’s major river basins. Historical observations indicate that water resources declined in over 40% of the country， with an 80% confidence interval of -4.13 to -2.01 mm/a. Under the SSP126， SSP370， and SSP585 scenarios， water resources show overall increases but with significant spatiotemporal variability and uncertainty. For river basins in Southwest China， the projected variation ranges are -11.16% to 20.49%， -14.70% to 28.62%， and -10.89% to 46.43%， respectively. Attribution analysis across nine representative basins reveals that reduced precipitation and increased potential evapotranspiration jointly drive water resource declines in more than 60% of years， with dominant drivers varying by basin and scenario. The relative contribution of decreasing precipitation gradually increases with rising aridity index. Reduced precipitation remains the dominant factor in arid regions， with contribution on rates of 0.93 for the historical period and 0.65， 0.60， and 0.60 for the three future emission scenarios， respectively. This study provides a scientific basis for the long-term optimal allocation of water resources in China’s major river basins.关键词：water resources;Budyko equation;evapotranspiration;total differential equation;climate change4|3|0更新时间：2026-05-15
- 摘要：The upper reaches of the Hanjiang River are located in the north-south climatic transition zone of China， where sedimentary sequences are crucial for revealing the evolution history of the East Asian monsoon. This study examined the Mituosi profile in the upper Hanjiang River. Chromaticity parameters were systematically measured and integrated with magnetic susceptibility and grain size to assess their paleoclimatic significance and reconstruct the Holocene climate evolution. The results show that lightness L* is negatively correlated with Fe2O3 content （R=-0.83）. Influenced by organic matter content， L* values are lowest in the paleosol layer （average 48.41）， reflecting strong pedogenesis. Redness a* exhibits a significant positive correlation with Fe₂O₃ content （R=0.77）， reaching peak value in the paleosol layer （average 4.99）. This reflects the enrichment of iron oxides under warm and humid conditions. Yellowness b* and hue angle h* display maximum values in the cold-dry Malan loess unit and decline in the paleosol layer. Conversely， the a*/b* ratio shows an opposite trend to h*， with a high value （average 0.39） in the paleosol layer. Significant correlations among chromaticity parameters and magnetic susceptibility， clay content， and the Rb/Sr ratio confirming their utility as reliable paleoclimate proxies. The record reveals a cold， dry early Holocene （11.5~8.0 ka BP） characterized by weak pedogenesis. This was followed by warm， humid mid-Holocene （8.0~3.1 ka BP）with strong pedogenesis， albeit interrupted by a significant cold-dry event at ~6.48 ka BP. The late Holocene （since ~3.1 ka BP） saw a return to cold， dry climates. These findings not only provide new evidence for paleoclimate reconstruction in the upper Hanjiang River but also enhance our understanding of climate dynamics in the north-south transition zone.关键词：paleoclimate reconstruction;chromaticity parameter;climate evolution;Holocene;upper Hanjiang river4|15|0更新时间：2026-05-15
- 摘要：Elevated structures at the block scale can hinder the diffusion of atmospheric particulate matter， leading to localized pollutant accumulation. To investigate the distribution characteristics of pollutant matter in these areas and their influencing factors， this study focused on the space under the East First Ring Elevated Expressway in Nanchang. Continuous field monitoring was conducted over 5 days， covering morning， afternoon， and evening rush hours at multiple locations （10 sites and 30 sampling points）. This was combined with numerical simulations using ANSYS Fluent to analyze the spatiotemporal distribution of PM2.5 and PM10 and their key influencing factors. The results indicated that： 1）Temporally， the particulate matter concentrations followed the order "afternoon rush hour> morning rush hour> evening rush hour"， and were significantly higher on weekdays than on weekends. 2） Spatially， high-concentration areas are primarily at intersections and zones directly beneath the bridge deck， while low-concentration areas are more prevalent at T-junctions and ramp spaces. Areas with higher concentrations typically featured wider bridge decks and roads. 3）Particulate matter concentration show significant positive correlations with relative humidity， traffic flow， and black globe temperature， and significant negative correlations with air temperature. 4）Numerical simulations reveal a significant positive correlation between concentration and wind speed at low wind speeds. The elevated bridge structure reduces wind speed underneath it， creating a stagnation zone for pollutants. Different configurations of the elevated bridges and surrounding buildings generated distinct wind fields， which in turn affect particulate matter concentration variation. This study provides a scientific basis for improving environmental quality and preventing health risks in the spaces under elevated highways.关键词：under-bridge space;particulate matter;spatio-temporal distribution;air flow field;Nanchang6|9|0更新时间：2026-05-15
- 摘要：Existing low-strain-rate dynamic loading devices are generally characterized by complex structures and high costs， while pulse loading modes other than compression remain underdeveloped. To address these issues， this paper proposes four novel low-strain-rate pulse loading devices， which cover tensile， compressive， tensile-compressive mixed， and impact loading modes. Their working principles are systematically elaborated， the pulse loading performance of the four types of devices is verified through experiments， and the regulation laws of pulse waveforms are analyzed and summarized. The results demonstrate that： 1） All four devices can achieve the corresponding pulse loading； the amplitude of the output tensile pulse is proportional to the falling height of the weight， and the pulse width is proportional to the elasticity of the thin string； 2） The amplitudes of the output compressive and tensile-compressive mixed pulses of the four devices are proportional to the exciter voltage， while the pulse width is inversely proportional to the operating frequency； 3） The impact pulse velocity output by the four devices is proportional to the spring compression amount. This research enriches the types of low-strain-rate dynamic loading devices and provides a low-cost， precise， and adjustable experimental method for research in related fields.关键词：low strain rate;dynamic loading;pulse loading device;loading performance;pulse waveform regulation17|20|0更新时间：2026-05-11
- 摘要：The year 2025 marked the passing of two towering figures of twentieth-century mathematical physics, Rodney Baxter and Chen-Ning Yang. Yang reshaped modern physics through the introduction of non-abelian gauge theory and, independently, through the consistency conditions that later became known as the Yang-Baxter equation. Baxter transformed those conditions into a systematic theory of exact solvability in statistical mechanics and quantum integrable systems.This article is written in memory of Baxter and Yang, whose work revealed how local consistency principles generate global mathematical structure. We review the Yang-Mills formulation of gauge theory, its mass obstruction and resolution via symmetry breaking, and the geometric framework it engendered, including instantons, Donaldson-Floer theory, magnetic monopoles, and Hitchin systems. In parallel, we trace the emergence of the Yang-Baxter equation from factorised scattering to solvable lattice models, quantum groups, and Chern-Simons theory. Rather than presenting two separate narratives, gauge theory and integrability are presented as complementary manifestations of a shared coherence principle - an ongoing journey from gauge symmetry toward mathematical unity.关键词：Yang-Mills theory;Yang-Baxter equation;gauge theory;quantum groups;mirror symmetry14|15|0更新时间：2026-05-11
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