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   504篇
  免费   75篇
  2021年   11篇
  2020年   7篇
  2019年   4篇
  2018年   7篇
  2017年   8篇
  2016年   9篇
  2015年   20篇
  2014年   16篇
  2013年   28篇
  2012年   28篇
  2011年   24篇
  2010年   12篇
  2009年   9篇
  2008年   8篇
  2007年   15篇
  2006年   13篇
  2005年   16篇
  2004年   18篇
  2003年   21篇
  2002年   8篇
  2001年   23篇
  2000年   7篇
  1999年   11篇
  1998年   12篇
  1997年   14篇
  1996年   4篇
  1995年   12篇
  1994年   5篇
  1993年   5篇
  1992年   12篇
  1991年   4篇
  1990年   11篇
  1989年   13篇
  1988年   13篇
  1987年   12篇
  1986年   8篇
  1985年   7篇
  1983年   8篇
  1982年   6篇
  1980年   5篇
  1979年   5篇
  1978年   4篇
  1977年   4篇
  1976年   11篇
  1970年   7篇
  1964年   5篇
  1962年   3篇
  1943年   3篇
  1942年   3篇
  1910年   4篇
排序方式: 共有579条查询结果,搜索用时 15 毫秒
111.
Pox-1, a mutant of Salmonella typhimurium, strongly channels P22 toward lysogeny. Viral DNA synthesis in this slow-growing mutant is delayed to a greater extent than viral protein synthesis. The relative enhancement of c2 repressor synthesis results in much higher repressor/DNA synthesis ratios in Pox-1 than in wild-type cells. This probably accounts for the high frequency of lysogenization.  相似文献   
112.
113.
Infant Feeding     
Wm. F. Gough 《CMAJ》1953,68(6):544-546
  相似文献   
114.
115.
The two murine haemopoietic growth factors, granulocyte-macrophage colony stimulating factor (GM-CSF) and Multi-CSF (interleukin 3) stimulate the proliferation and differentiation of an overlapping set of haemopoietic progenitor cells and are produced coordinately following activation of T lymphocytes. Here we report the chromosomal location of the genes encoding these two factors. Initially both genes were assigned to chromosome 11 by analysis of mouse/Chinese hamster somatic cell hybrids. Genetic analysis using an interspecies (Mus musculus X Mus spretus) back-cross confirmed this assignment by demonstrating that both the GM-CSF and Multi-CSF genes are genetically linked to the SPARC gene, which had been independently assigned to sub-band B1 of chromosome 11. Analysis of physical distances by pulsed field gel electrophoresis demonstrated further that the two CSF genes lie within 230 kb of each other. However examination of the subchromosomal region containing all three loci by pulsed field gel analysis showed that SPARC is at least 400-500 kb distant from the region containing the two CSF genes.  相似文献   
116.
Levels of anti-Candida albicans immunoglobulin A (IgA) and IgG were measured by enzyme-linked immunosorbent assay in serum and cervicovaginal secretions from 64 non-pregnant women with vaginal candidosis and 158 uninfected non-pregnant women. Specific IgA and IgG were detected in the serum and secretions of all 222 women. There was no significant difference between the mean levels of specific IgA or IgG in secretions from women with candidosis and those of uninfected women. Neither was there a significant difference between mean levels of specific IgA or IgG when women using oral contraception were compared with others who were not. There was a significant correlation between the levels of IgA and IgG in serum and secretions from women with candidosis and from uninfected women. Blastospore and hyphal forms of C. albicans were seen in vaginal smears from 29 of the 64 women with culture-proven candidosis: in nine, both IgA- and IgG-coated C. albicans cells were recovered from the genital tract; in a tenth, IgG-coated cells were found.  相似文献   
117.
The higher-level taxonomy of tiger beetles is re-evaluated in light of recent publications based on large taxon sets and a large number of genetic loci. These studies have demonstrated that tiger beetles are a distinct family, Cicindelidae Latreille, sister to the Carabidae Latreille (ground beetles) or Trachypachidae Thomson (false ground beetles) + Carabidae. Recent phylogenies have also recovered consistent patterns in higher-level relationships within the tiger beetles that challenge the traditional taxonomic framework, most of which is more than a century old. These phylogenetic results are reviewed along with concordant morphological characters to create an updated higher-level classification. The subfamily Collyrinae Csiki is not supported by any modern data. We recognize six tribes, Manticorini Laporte (new sense), Megacephalini Laporte (new sense), Collyridini Brullé, Ctenostomatini Laporte, Cicindelini Latreille and the reinstated Oxycheilini Chaudoir (with emended spelling).  相似文献   
118.
The continued development of effective anti-tick vaccines remains the most promising prospect for the control of the cattle tick, Rhipicephalus (Boophilus) microplus. A vaccine based on midgut proteins could interfere with successful tick feeding and additionally interfere with midgut developmental stages of Babesia parasites, providing opportunities for the control of both the tick and the pathogens it transmits. Midgut proteins from partially fed adult female cattle ticks were analysed using a combination of 2-DE and gel-free LC-MS/MS. Analysis of the urea-soluble protein fraction resulted in the confident identification of 105 gut proteins, while the PBS-soluble fraction yielded an additional 37 R. microplus proteins. The results show an abundance of proteins involved in mitochondrial ATP synthesis, electron transport chain, protein synthesis, chaperone, antioxidant and protein folding and transport activities in midgut tissues of adult female ticks. Among the novel products identified were clathrin-adaptor protein, which is involved in the assembly of clathrin-coated vesicles, and membrane-associated trafficking proteins such as syntaxin 6 and surfeit 4. The observations allow the formulation of hypotheses regarding midgut physiology and will serve as a basis for future vaccine development and tick-host interaction research.  相似文献   
119.
120.
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