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Ke Tao Rocha Joao B. T. Tinkov Alexey A. Santamaria Abel Bowman Aaron B. Aschner Michael 《Neurochemical research》2021,46(11):2991-3002
Neurochemical Research - Methylmercury (MeHg) exposure and its harmful effects on the developing brain continue to be a global environmental health concern. Decline in mitochondrial function is... 相似文献
74.
R. Aaron Rogers Madeline R. Meyer Kayla M. Stewart Gabriela M. Eyring Aaron M. Fleming Cynthia J. Burrows 《Biopolymers》2021,112(1)
In DNA, i‐motif (iM) folds occur under slightly acidic conditions when sequences rich in 2′‐deoxycytidine (dC) nucleotides adopt consecutive dC self base pairs. The pH stability of an iM is defined by the midpoint in the pH transition (pHT) between the folded and unfolded states. Two different experiments to determine pHT values via circular dichroism (CD) spectroscopy were performed on poly‐dC iMs of length 15, 19, or 23 nucleotides. These experiments demonstrate two points: (1) pHT values were dependent on the titration experiment performed, and (2) pH‐induced denaturing or annealing processes produced isothermal hysteresis in the pHT values. These results in tandem with model iMs with judicious mutations of dC to thymidine to favor particular folds found the hysteresis was maximal for the shorter poly‐dC iMs and those with an even number of base pairs, while the hysteresis was minimal for longer poly‐dC iMs and those with an odd number of base pairs. Experiments to follow the iM folding via thermal changes identified thermal hysteresis between the denaturing and annealing cycles. Similar trends were found to those observed in the CD experiments. The results demonstrate that the method of iM analysis can impact the pHT parameter measured, and hysteresis was observed in the pHT and Tm values. 相似文献
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Samantha J. Emery-Corbin Joshua J. Hamey Balu Balan Laura Rojas-López Staffan G. Svärd Aaron R. Jex 《International journal for parasitology》2021,51(4):225-239
Diarrheal disease caused by Giardia duodenalis is highly prevalent, causing over 200 million cases globally each year. The processes that drive parasite virulence, host immune evasion and transmission involve coordinated gene expression and have been linked to epigenetic regulation. Epigenetic regulatory systems are eukaryote-conserved, including in deep branching excavates such as Giardia, with several studies already implicating histone post-translational modifications in regulation of its pathogenesis and life cycle. However, further insights into Giardia chromatin dynamics have been hindered by a lack of site-specific knowledge of histone modifications. Using mass spectrometry, we have provided the first known molecular map of histone methylation, acetylation and phosphorylation modifications in Giardia core histones. We have identified over 50 previously unreported histone modifications including sites with established roles in epigenetic regulation, and co-occurring modifications indicative of post-translational modification crosstalk. These demonstrate conserved histone modifications in Giardia which are equivalent to many other eukaryotes, and suggest that similar epigenetic mechanisms are in place in this parasite. Further, we used sequence, domain and structural homology to annotate putative histone enzyme networks in Giardia, highlighting representative chromatin modifiers which appear sufficient for identified sites, particularly those from H3 and H4 variants. This study is to our knowledge the first and most comprehensive, complete and accurate view of Giardia histone post-translational modifications to date, and a substantial step towards understanding their associations in parasite development and virulence. 相似文献
78.
Victoria Uribe Paul S. Wills Jon M. Shenker Aaron J. Adams Sahar Mejri 《Journal of fish biology》2021,99(6):1778-1785
Little is known about early development of the near-threatened bonefish (Albula vulpes), a member of superorder Elopomorpha. Members of Elopomorpha are partially defined by their synapomorphic leptocephalus larval stage, for which the nutritional requirements are not well understood. Characterizing the nutritional profile, including major nutrients (such as lipids) used for energetic processes, can help to gain a better understanding of the nutritional requirements for leptocephalus larvae. A total of 24 settlement stage A. vulpes leptocephalus larvae were collected at Long Caye Island, Belize. Samples were used to determine various biochemical characteristics including lipid class, fatty acid and glycosaminoglycan compositions. Each of these biochemical components plays a role in early developmental processes such as cellular membrane formation and is crucial for healthy development. Biochemical characteristics of settlement stage A. vulpes leptocephalus are presented in this study for the first time. The dominant lipid classes and fatty acids detected in these samples were consistent with prior studies using closely related species like the Japanese eel, indicating possible similarities in diets at this stage. In the future, similar analyses can be applied to other species that share the leptocephalus life stage to determine if nutritional requirements at this stage of development are unique to this species. The findings in this study will also help to facilitate the establishment of adequate aquaculture systems for captive bonefish, ultimately leading to improved management strategies for wild bonefish habitats. 相似文献
79.
Natalie V. Klinard Jordan K. Matley Silviya V. Ivanova Sarah M. Larocque Aaron T. Fisk Timothy B. Johnson 《Journal of fish biology》2021,98(1):237-250
Understanding predator–prey interactions and food web dynamics is important for ecosystem-based management in aquatic environments, as they experience increasing rates of human-induced changes, such as the addition and removal of fishes. To quantify the post-stocking survival and predation of a prey fish in Lake Ontario, 48 bloater Coregonus hoyi were tagged with acoustic telemetry predation tags and were tracked on an array of 105 acoustic receivers from November 2018 to June 2019. Putative predators of tagged bloater were identified by comparing movement patterns of six species of salmonids (i.e., predators) in Lake Ontario with the post-predated movements of bloater (i.e., prey) using a random forests algorithm, a type of supervised machine learning. A total of 25 bloater (53% of all detected) were consumed by predators on average (± S.D. ) 3.1 ± 2.1 days after release. Post-predation detections of predators occurred for an average (± S.D. ) of 78.9 ± 76.9 days, providing sufficient detection data to classify movement patterns. Tagged lake trout Salvelinus namaycush provided the most reliable classification from behavioural predictor variables (89% success rate) and was identified as the main consumer of bloater (consumed 50%). Movement networks between predicted and tagged lake trout were significantly correlated over a 6 month period, supporting the classification of lake trout as a common bloater predator. This study demonstrated the ability of supervised learning techniques to provide greater insight into the fate of stocked fishes and predator–prey dynamics, and this technique is widely applicable to inform future stocking and other management efforts. 相似文献
80.
Steffen H. Büttner Eric W. Isemonger Michelle Isaacs Deon van Niekerk Rachel E. Sipler Rosemary A. Dorrington 《Geobiology》2021,19(1):35-47
In the geological record, fossil phosphatic stromatolites date back to the Great Oxidation Event in the Paleoproterozoic, but living phosphatic stromatolites have not been described previously. Here, we report on cyanobacterial stromatolites in a supratidal freshwater environment at Cape Recife, South African southern coast, precipitating Ca carbonate alternating with episodes of Ca phosphate deposition. In their structure and composition, the living stromatolites from Cape Recife closely resemble their fossilized analogues, showing phosphatic zonation, microbial casts, tunnel structures and phosphatic crusts of biogenic origin. The microbial communities appear to be also similar to those proposed to have formed fossil phosphatic stromatolites. Phosphatic domains in the material from Cape Recife are spatially and texturally associated with carbonate precipitates, but form distinct entities separated by sharp boundaries. Electron Probe Micro‐Analysis shows that Ca/P ratios and the overall chemical compositions of phosphatic precipitates are in the range of octacalcium phosphate, amorphous tricalcium phosphate and apatite. The coincidence in time of the emergence of phosphatic stromatolites in the fossil record with a major episode of atmospheric oxidation led to the assumption that at times of increased oxygen release the underlying increased biological production may have been linked to elevated phosphorus availability. The stromatolites at Cape Recife, however, form in an environment where ambient phosphorus concentrations do not exceed 0.28 μM, one to two orders of magnitude below the previously predicted minimum threshold of >5 μM for biogenic phosphate precipitation in paleo‐systems. Accordingly, we contest the previously proposed suitability of phosphatic stromatolites as a proxy for high ambient phosphate concentrations in supratidal to shallow ocean settings in earth history. 相似文献