全文获取类型
收费全文 | 9260篇 |
免费 | 783篇 |
国内免费 | 1篇 |
出版年
2022年 | 75篇 |
2021年 | 203篇 |
2020年 | 111篇 |
2019年 | 138篇 |
2018年 | 210篇 |
2017年 | 156篇 |
2016年 | 220篇 |
2015年 | 328篇 |
2014年 | 430篇 |
2013年 | 547篇 |
2012年 | 625篇 |
2011年 | 629篇 |
2010年 | 382篇 |
2009年 | 349篇 |
2008年 | 436篇 |
2007年 | 478篇 |
2006年 | 452篇 |
2005年 | 385篇 |
2004年 | 395篇 |
2003年 | 385篇 |
2002年 | 343篇 |
2001年 | 191篇 |
2000年 | 161篇 |
1999年 | 149篇 |
1998年 | 101篇 |
1997年 | 81篇 |
1996年 | 65篇 |
1995年 | 69篇 |
1994年 | 69篇 |
1993年 | 68篇 |
1992年 | 92篇 |
1991年 | 89篇 |
1990年 | 94篇 |
1989年 | 75篇 |
1988年 | 64篇 |
1987年 | 62篇 |
1986年 | 69篇 |
1985年 | 66篇 |
1984年 | 86篇 |
1983年 | 57篇 |
1982年 | 56篇 |
1981年 | 47篇 |
1979年 | 44篇 |
1978年 | 50篇 |
1977年 | 58篇 |
1976年 | 48篇 |
1975年 | 60篇 |
1974年 | 46篇 |
1973年 | 73篇 |
1972年 | 51篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Patricia A. Marshall 《Medical anthropology quarterly》1998,12(2):250-252
Sickness and Healing: An Anthropological Perspective. Robert A. Hahn. New Haven, CT: Yale University Press, 1995 (cloth and paper), viii. 327 pp. 相似文献
12.
13.
Sergio Davinelli Mariano Intrieri Claudio Russo Alfonso Di Costanzo Davide Zella Paolo Bosco Giovanni Scapagnini 《Immunity & ageing : I & A》2011,8(1):1-10
Alzheimer's disease is a progressive and neurodegenerative disorder which involves multiple molecular mechanisms. Intense research during the last years has accumulated a large body of data and the search for sensitive and specific biomarkers has undergone a rapid evolution. However, the diagnosis remains problematic and the current tests do not accurately detect the process leading to neurodegeneration. Biomarkers discovery and validation are considered the key aspects to support clinical diagnosis and provide discriminatory power between different stages of the disorder. A considerable challenge is to integrate different types of data from new potent approach to reach a common interpretation and replicate the findings across studies and populations. Furthermore, long-term clinical follow-up and combined analysis of several biomarkers are among the most promising perspectives to diagnose and manage the disease. The present review will focus on the recent published data providing an updated overview of the main achievements in the genetic and biochemical research of the Alzheimer's disease. We also discuss the latest and most significant results that will help to define a specific disease signature whose validity might be clinically relevant for future AD diagnosis. 相似文献
14.
S. V. Marshall 《BMJ (Clinical research ed.)》1939,1(4079):535-536
15.
16.
Sergio M. Villordo Claudia V. Filomatori Irma Sánchez-Vargas Carol D. Blair Andrea V. Gamarnik 《PLoS pathogens》2015,11(1)
Many viral pathogens cycle between humans and insects. These viruses must have evolved strategies for rapid adaptation to different host environments. However, the mechanistic basis for the adaptation process remains poorly understood. To study the mosquito-human adaptation cycle, we examined changes in RNA structures of the dengue virus genome during host adaptation. Deep sequencing and RNA structure analysis, together with fitness evaluation, revealed a process of host specialization of RNA elements of the viral 3’UTR. Adaptation to mosquito or mammalian cells involved selection of different viral populations harvesting mutations in a single stem-loop structure. The host specialization of the identified RNA structure resulted in a significant viral fitness cost in the non-specialized host, posing a constraint during host switching. Sequence conservation analysis indicated that the identified host adaptable stem loop structure is duplicated in dengue and other mosquito-borne viruses. Interestingly, functional studies using recombinant viruses with single or double stem loops revealed that duplication of the RNA structure allows the virus to accommodate mutations beneficial in one host and deleterious in the other. Our findings reveal new concepts in adaptation of RNA viruses, in which host specialization of RNA structures results in high fitness in the adapted host, while RNA duplication confers robustness during host switching. 相似文献
17.
Loïc Pellissier Charlotte Ndiribe Anne Dubuis Jean‐Nicolas Pradervand Nicolas Salamin Antoine Guisan Sergio Rasmann 《Ecology letters》2013,16(5):600-608
Understanding drivers of biodiversity patterns is of prime importance in this era of severe environmental crisis. More diverse plant communities have been postulated to represent a larger functional trait‐space, more likely to sustain a diverse assembly of herbivore species. Here, we expand this hypothesis to integrate environmental, functional and phylogenetic variation of plant communities as factors explaining the diversity of lepidopteran assemblages along elevation gradients in the Swiss Western Alps. According to expectations, we found that the association between butterflies and their host plants is highly phylogenetically structured. Multiple regression analyses showed the combined effect of climate, functional traits and phylogenetic diversity in structuring butterfly communities. Furthermore, we provide the first evidence that plant phylogenetic beta diversity is the major driver explaining butterfly phylogenetic beta diversity. Along ecological gradients, the bottom up control of herbivore diversity is thus driven by phylogenetically structured turnover of plant traits as well as environmental variables. 相似文献
18.
19.
20.