首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3065篇
  免费   356篇
  国内免费   1篇
  2021年   32篇
  2020年   17篇
  2019年   25篇
  2018年   36篇
  2017年   28篇
  2016年   70篇
  2015年   126篇
  2014年   114篇
  2013年   133篇
  2012年   153篇
  2011年   143篇
  2010年   98篇
  2009年   83篇
  2008年   128篇
  2007年   122篇
  2006年   112篇
  2005年   131篇
  2004年   103篇
  2003年   92篇
  2002年   103篇
  2001年   105篇
  2000年   92篇
  1999年   89篇
  1998年   49篇
  1997年   37篇
  1996年   44篇
  1995年   36篇
  1994年   32篇
  1993年   61篇
  1992年   69篇
  1991年   66篇
  1990年   99篇
  1989年   81篇
  1988年   74篇
  1987年   62篇
  1986年   56篇
  1985年   48篇
  1984年   41篇
  1983年   40篇
  1982年   28篇
  1981年   21篇
  1980年   20篇
  1979年   34篇
  1978年   42篇
  1977年   38篇
  1976年   30篇
  1975年   23篇
  1974年   20篇
  1973年   21篇
  1971年   17篇
排序方式: 共有3422条查询结果,搜索用时 15 毫秒
1.
2.
The Species Survival Commission (SSC) of IUCN—the World Conservation Union is the largest, most comprehensive and diverse professional conservation network in existence today. It brings together over 6000 volunteers from more than 160 countries to contribute to the conservation of biological diversity by developing and executing programmes to study, save, restore, and manage wisely species and their habitats. The SSC is organized primarily along taxonomic lines, with members distributed in 96 Specialist Groups focusing on distinct groups of species. These groups are a source of the most current and expert information on the conservation status and priorities for action for species in the wild. As such, they provide an invaluable resource in setting priorities for captive propagation and in linking ex situ actions. In addition, the SSC has five disciplinary Specialist Groups that provide expertise to both the zoo community and field conservationists in areas such as reintroductions, veterinary medicine, captive breeding as a conservation tool, and the impact of invasive species on native flora and fauna. The effectiveness of the SSC is greatly enhanced by the close connections within its network between zoo professionals, academic scientists, field conservationists, and managers of natural resources. Challenges to the SSC currently include better information management, organization at the national level, and extending coverage in areas such as marine biodiversity.  相似文献   
3.
Retinitis pigmentosa is a genetically heterogeneous form of retinal degeneration, which has X-linked, autosomal recessive and autosomal dominant forms. The disease genes in families with autosomal dominant retinitis pigmentosa (adRP) have been linked to six loci, on 3q, 6p, 7p, 7q, 8q and 19q. In a large American family with late-onset adRP, microsatellite markers were used to test for linkage to the loci on 3q, 6p, 7p, 7q and 8q. Linkage was found to 7q using the marker D7S480. Additional microsatellite markers from 7q were then tested. In total, five markers, D7S480, D7S514, D7S633, D7S650 and D7S677, show statistically significant evidence for link-age in this family, with a maximum two-point lod score of 5.3 at 0% recombination from D7S514. These results confirm an earlier report of linkage to an adRP locus (RP10) in an unrelated family of Spanish origin and indicate that RP10 may be a significant gene for inherited retinal degeneration. In addition, we used recently reported microsatellite markers from 7q to refine the linkage map of the RP10 locus.  相似文献   
4.
RFLP haplotypes at the phenylalanine hydroxylase (PAH) locus were determined in 45 nuclear Caucasian families from Switzerland and Scotland. The RFLPs at the PAH locus are highly informative, and prenatal diagnosis is possible in 85% of the families studied. The data were combined with the profiles previously observed in the Danish population, in order to study the variation in RFLP haplotype distribution among European populations. A total of 22 different haplotypes were observed in Denmark, Switzerland, and Scotland. Fifteen and 19 haplotypes are associated with the normal (non-PKU) and with the mutant chromosomes, respectively. The haplotype distribution and the allele frequency of normal chromosomes remain constant between Denmark, Switzerland, and Scotland. However, both the haplotype distribution and allele frequencies of mutant chromosomes show significant variation between the three countries. Our results suggest there may be additional mutations in the PAH gene that cause PKU.  相似文献   
5.

Introduction  

The aim of this study was to examine IL-17A in patients, following anti-TNF-α therapy and the effect of IL-17A on matrix turnover and cartilage degradation.  相似文献   
6.
7.
8.
9.
10.
In this study a model system for expression of the chicken progesterone receptor in cultured cells was developed using a quail fibroblast cell line, QT6. The chicken progesterone receptor form A expressed in QT6 cells was evaluated and determined to have a number of similarities to receptor isolated from chicken oviduct. These include hormone binding, sedimentation profile, phosphorylation pattern, heat shock protein (hsp) 70 and hsp90 associations and the ability to stimulate a reporter gene construct. Therefore, the receptor expressed in this system functioned adequately for further evaluation of the particular region (or regions) involved in hsp70 and hsp90 binding. Several receptor deletion mutants were tested for hsp70/hsp90 binding; only the d369-659 mutant, which has the entire steroid-binding domain deleted, was unable to bind hsp90 and hsp70. Three separate regions of the steroid-binding domain were found to partially restore hsp90 and hsp70 binding to the d369-659 mutant protein. However, hsp binding was not abolished when these or other regions of the steroid binding domain were deleted individually. These findings indicate that hsp90 and hsp70 both bind to the steroid-binding domain of the receptor through interactions at multiple locations or through some structural quality that is distributed throughout this region of the protein.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号