全文获取类型
收费全文 | 1786篇 |
免费 | 217篇 |
出版年
2021年 | 22篇 |
2020年 | 17篇 |
2019年 | 24篇 |
2018年 | 17篇 |
2017年 | 27篇 |
2016年 | 44篇 |
2015年 | 63篇 |
2014年 | 80篇 |
2013年 | 88篇 |
2012年 | 119篇 |
2011年 | 122篇 |
2010年 | 83篇 |
2009年 | 58篇 |
2008年 | 84篇 |
2007年 | 59篇 |
2006年 | 59篇 |
2005年 | 53篇 |
2004年 | 57篇 |
2003年 | 59篇 |
2002年 | 57篇 |
2001年 | 52篇 |
2000年 | 45篇 |
1999年 | 41篇 |
1998年 | 28篇 |
1997年 | 21篇 |
1996年 | 32篇 |
1995年 | 20篇 |
1994年 | 24篇 |
1993年 | 20篇 |
1992年 | 26篇 |
1991年 | 30篇 |
1990年 | 31篇 |
1989年 | 33篇 |
1988年 | 22篇 |
1987年 | 22篇 |
1986年 | 22篇 |
1984年 | 23篇 |
1983年 | 20篇 |
1982年 | 15篇 |
1981年 | 16篇 |
1980年 | 14篇 |
1979年 | 17篇 |
1976年 | 16篇 |
1974年 | 18篇 |
1973年 | 14篇 |
1972年 | 14篇 |
1971年 | 17篇 |
1969年 | 21篇 |
1967年 | 13篇 |
1966年 | 14篇 |
排序方式: 共有2003条查询结果,搜索用时 31 毫秒
1.
2.
Does indocyanine green obey Beer's law? 总被引:2,自引:0,他引:2
3.
M McEvoy K Porter P Mortimer N Simmons D Shanson 《BMJ (Clinical research ed.)》1987,294(6587):1595-1597
In a prospective study of 150 health care workers in the United Kingdom who had been accidentally exposed to the human immunodeficiency virus no evidence of transmission was found. Larger studies in the United States and anecdotal accounts in publications from other countries confirm that the risk of occupational infection is very low. Health care workers must adopt safe procedures at all times, however, to avoid exposure to infection. 相似文献
4.
P D Simmons 《BMJ (Clinical research ed.)》1980,280(6227):1323
5.
Wendy A. Douglass Robert H. Hyland Christopher D. Buckley Aymen Al-Shamkhani Jacqueline M. Shaw Sarah L. Scarth David L. Simmons S.K.Alex Law 《FEBS letters》1998,440(3):125
The cysteine-rich region (CRR) of the β2 integrin subunit was replaced by that of β1 to give the chimera β2NV1. β2NV1 can combine with αL to form a variant leukocyte-function-associated antigen (LFA)-1 on COS cell surface, suggesting that the specificity of the β2 interaction with αL does not lie in the CRR. Unlike those expressing wild-type LFA-1, COS cells expressing αLβ2NV1 are constitutively active in intercellular adhesion molecule (ICAM)-1 adhesion. These results suggest that activation of LFA-1 involves the release of an intramolecular constraint, which is maintained, in part, by the authentic β2 CRR. 相似文献
6.
Nicolas J. Dowdy Shannon Keating Alan R. Lemmon Emily M. Lemmon William E. Conner Clare H. Scott Chialvo Susan J. Weller Rebecca B. Simmons Melissa S. Sisson Jennifer M. Zaspel 《Systematic Entomology》2020,45(4):874-893
Anchored hybrid enrichment (AHE) has emerged as a powerful tool for uncovering the evolutionary relationships within many taxonomic groups. AHE probe sets have been developed for a variety of insect groups, though none have yet been shown to be capable of simultaneously resolving deep and very shallow (e.g., intraspecific) divergences. In this study, we present NOC1, a new AHE probe set (730 loci) for Lepidoptera specialized for tiger moths and assess its ability to deliver phylogenetic utility at all taxonomic levels. We test the NOC1 probe set with 142 individuals from 116 species sampled from all the major lineages of Arctiinae (Erebidae), one of the most diverse groups of noctuoids (>11 000 species) for which no well-resolved, strongly supported phylogenetic hypothesis exists. Compared to previous methods, we generally recover much higher branch support (BS), resulting in the most well-supported, well-resolved phylogeny of Arctiinae to date. At the most shallow-levels, NOC1 confidently resolves species-level and intraspecific relationships and potentially uncovers cryptic species diversity within the genus Hypoprepia. We also implement a ‘sensitivity analysis’ to explore different loci combinations and site sampling strategies to determine whether a reduced probe set can yield results similar to those of the full probe set. At both deep and shallow levels, only 50–175 of the 730 loci included in the complete NOC1 probe set were necessary to resolve most relationships with high confidence, though only when the more rapidly evolving sites within each locus are included. This demonstrates that AHE probe sets can be tailored to target fewer loci without a significant reduction in BS, allowing future studies to incorporate more taxa at a lower per-sample sequencing cost. NOC1 shows great promise for resolving long-standing taxonomic issues and evolutionary questions within arctiine lineages, one of the most speciose clades within Lepidoptera. 相似文献
7.
8.
9.
10.
A G Yersin F W Edens D G Simmons 《Comparative biochemistry and physiology. B, Comparative biochemistry》1990,97(4):755-759
1. Liver tryptophan 2,3-dioxygenase (TPO) activity was depressed significantly by the Bordetella avium infection localized in the trachea of the turkey poult. 2. Tryptophan, given orally, induced a significant increase in TPO activity in both control and infected poults. 3. Hydrocortisone induced TPO activity in the turkey in a dose dependent manner. 相似文献