全文获取类型
收费全文 | 3102篇 |
免费 | 242篇 |
出版年
2024年 | 5篇 |
2023年 | 23篇 |
2022年 | 65篇 |
2021年 | 109篇 |
2020年 | 48篇 |
2019年 | 84篇 |
2018年 | 113篇 |
2017年 | 109篇 |
2016年 | 132篇 |
2015年 | 190篇 |
2014年 | 200篇 |
2013年 | 227篇 |
2012年 | 269篇 |
2011年 | 272篇 |
2010年 | 165篇 |
2009年 | 120篇 |
2008年 | 193篇 |
2007年 | 191篇 |
2006年 | 165篇 |
2005年 | 136篇 |
2004年 | 123篇 |
2003年 | 98篇 |
2002年 | 87篇 |
2001年 | 22篇 |
2000年 | 16篇 |
1999年 | 19篇 |
1998年 | 27篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 12篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1961年 | 3篇 |
排序方式: 共有3344条查询结果,搜索用时 15 毫秒
991.
992.
993.
Mailén E. Lallement Magalí Rechencq María V. Fernández Eduardo Zattara Alejandro Sosnovsky Pablo Vigliano Gilda Garibotti Marcelo F. Alonso Gustavo Lippolt Patricio J. Macchi 《Journal of fish biology》2020,97(3):753-762
Understanding how ecosystem processes influencing fish distribution operate across spatial scales is important to understand biological invasions. Salmonids, originally from the Northern Hemisphere, have been repeatedly introduced throughout the world, making them an ideal group to test hypotheses about factors driving invasions. We assessed the influence of environmental variables at the watershed scale on the abundance and structure of salmonid assemblages in the breeding streams of the Upper Limay river basin, Rio Negro, Argentina. We combined field captures with digital map data and geographic information systems to examine landscape-level patterns of salmonid abundance in 35 representative sub-basins of the environmental gradient. We employed a hierarchical cluster analysis and classification and regression tree models to relate the abundance of salmonids and types of species assemblages with environmental characteristics at watershed level. We found stream localization, precipitation regime, altitude and air temperature to be important predictors of the abundance and assemblage structure of salmonids. Total catches showed an increasing gradient of catch-per-unit-effort from west to east and from north to south, with Oncorhynchus mykiss being the most abundant species. O. mykiss relative abundance was westward skewed, where smaller catchments with steeper and shaded valleys are drained by less productive streams with more irregular hydrological regimes, like those found in this species' North American native range. In contrast, the abundance of Salmo trutta abundance was eastward skewed, where larger, sunnier and more gently sloped catchments result in more productive streams with stable hydrological regimes, like those found in that species' European native range. Thus, differential salmonid abundance could result from the interplay between the evolutionary fingerprint left by each species' native environment (especially flow and temperature regimes) and the availability of those conditions in new environments to which they have been translocated. By furthering our understanding of how landscape conditioned invasion success, these findings can help guide the management of economically important introduced fish. 相似文献
994.
995.
Marliete C. Costa Heliana de Barros Fernandes Gleisy K. N. Gonalves Anderson P. N. Santos Gabriella F. Ferreira Gustavo J. C. de Freitas Paulo H. F. do Carmo Jsy Hubner Elúzia C. P. Emídio Julliana R. A. Santos Jane L. dos Santos Adelina M. dos Reis Caio T. Fagundes Aristbolo M. da Silva Daniel A. Santos 《Cellular microbiology》2020,22(6)
Cryptococcus gattii (Cg) is one of the agents of cryptococcosis, a severe systemic mycosis with a higher prevalence in men than women, but the influence of the female sex hormone, 17‐β‐estradiol (E2), on cryptococcosis remains unclear. Our study shows that female mice presented delayed mortality, increased neutrophil recruitment in bronchoalveolar lavage fluid, and reduced fungal load after 24 hr of infection compared to male and ovariectomised female mice (OVX). E2 replacement restored OVX female survival. Female macrophages have more efficient fungicidal activity, which was increased by E2 and reversed by the antagonist of G‐protein‐coupled oestrogen receptor (GPER), which negatively modulates PI3K activation. Furthermore, E2 induces a reduction in Cg cell diameter, cell charge, and antioxidant peroxidase activity. In conclusion, female mice present improved control of Cg infection, and GPER is important for E2 modulation of the female response. 相似文献
996.
997.
Henry T. Robertson Gustavo de los Campos David B. Allison 《Obesity (Silver Spring, Md.)》2013,21(2):398-404
Objective:
We demonstrate the utility of parametric survival analysis. The analysis of longevity as a function of risk factors such as body mass index (BMI; kg/m2), activity levels, and dietary factors is a mainstay of obesity research. Modeling survival through hazard functions, relative risks, or odds of dying with methods such as Cox proportional hazards or logistic regression are the most common approaches and have many advantages. However, they also have disadvantages in terms of the ease of interpretability, especially for non‐statisticians; the need for additional data to convert parameter estimates to estimates of years of life lost (YLL); debates about the appropriate time scale in the model; and an inability to estimate median survival time when the censoring rate is too high.Design and Methods:
We will conduct parametric survival analyses with multiple distributions, including distributions that are known to be poor fits (Gaussian), as well as a newly discovered “Compressed Gaussian”'' distribution.Results:
Parametric survival analysis models were able to accurately estimate median survival times in a population‐based data set of 15,703 individuals, even for distributions that were not good fits and the censoring rate was high, due to the central limit theorem.Conclusions:
Parametric survival models are able to provide more direct answers, and in our analysis of an obesity‐related data set, gave consistent YLL estimates regardless of the distribution used. We recommend increased consideration of parametric survival models in chronic disease and risk factor epidemiology. 相似文献998.
Nelly Mezzaroba Sonia Zorzet Erika Secco Stefania Biffi Claudio Tripodo Marco Calvaruso Ramiro Mendoza-Maldonado Sara Capolla Marilena Granzotto Ruben Spretz Gustavo Larsen Sandra Noriega Marianna Lucafò Eduardo Mansilla Chiara Garrovo Gustavo H. Marín Gabriele Baj Valter Gattei Gabriele Pozzato Luis Nú?ez Paolo Macor 《PloS one》2013,8(9)
999.
Juan Gerez Mariana Fuertes Lucas Tedesco Susana Silberstein Gustavo Sevlever Marcelo Paez-Pereda Florian Holsboer Adrián G. Turjanski Eduardo Arzt 《PloS one》2013,8(2)
RSUME (RWD-containing SUMO Enhancer) is a small protein that increases SUMO conjugation to proteins. To date, four splice variants that codify three RSUME isoforms have been described, which differ in their C-terminal end. Comparing the structure of the RSUME isoforms we found that, in addition to the previously described RWD domain in the N-terminal, all these RSUME variants also contain an intermediate domain. Only the longest RSUME isoform presents a C-terminal domain that is absent in the others. Given these differences, we used the shortest and longest RSUME variants for comparative studies. We found that the C-terminal domain is dispensable for the SUMO-conjugation enhancer properties of RSUME. We also demonstrate that these two RSUME variants are equally induced by hypoxia. The NF-κB signaling pathway is inhibited and the HIF-1 pathway is increased more efficiently by the longest RSUME, by means of a greater physical interaction of RSUME267 with the target proteins. In addition, the mRNA and protein levels of these isoforms differ in human glioma samples; while the shortest RSUME isoform is expressed in all the tumors analyzed, the longest variant is expressed in most but not all of them. The results presented here show a degree of redundancy of the RSUME variants on the SUMO pathway. However, the increased inhibition conferred by RSUME267 over the NF-κB signaling pathway, the increased activation over the HIF-1 pathway and the different expression of the RSUME isoforms suggest specific roles for each RSUME isoform which may be relevant in certain types of brain tumors that express RSUME, like human pituitary adenomas and gliomas. 相似文献
1000.
Dorothée Sturm Lorella Marselli Florian Ehehalt Daniela Richter Marius Distler Stephan Kersting Robert Grützmann Krister Bokvist Philippe Froguel Robin Liechti Anne J?rns Paolo Meda Gustavo Bruno Baretton Hans-Detlev Saeger Anke M. Schulte Piero Marchetti Michele Solimena 《Journal of visualized experiments : JoVE》2013,(71)