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   258篇
  免费   22篇
  2022年   2篇
  2021年   4篇
  2019年   2篇
  2018年   3篇
  2017年   5篇
  2016年   3篇
  2015年   14篇
  2014年   19篇
  2013年   22篇
  2012年   22篇
  2011年   14篇
  2010年   8篇
  2009年   13篇
  2008年   11篇
  2007年   14篇
  2006年   15篇
  2005年   8篇
  2004年   9篇
  2003年   9篇
  2002年   2篇
  2001年   11篇
  2000年   12篇
  1999年   6篇
  1998年   12篇
  1997年   3篇
  1996年   3篇
  1995年   3篇
  1994年   3篇
  1993年   3篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1987年   3篇
  1986年   2篇
  1984年   2篇
  1983年   2篇
  1982年   1篇
  1981年   2篇
  1979年   1篇
  1976年   2篇
  1971年   1篇
  1967年   1篇
  1966年   2篇
排序方式: 共有280条查询结果,搜索用时 15 毫秒
271.
272.
Certain pulmonary stress raises rat lung Cu-Zn superoxide dismutase (SOD) activity levels, but cytokines released during stress are reported to exert no regulatory effects on Cu-Zn SOD levels in cultured cells. In contrast, our study found that interleukin 1 (IL-1) can increase Cu-Zn SOD activities in human W138 lung fibroblasts. The difference in results could be explained by differences in experimental conditions. The increases seen here did not occur during the first 24 hr, but Cu-Zn SOD activities more than doubled by 3 days. In addition, little increase occurred unless the medium was changed at 24-hr intervals. On the other hand, some other potential experimental variables showed little or no effects on IL-1-induced increases in Cu-Zn SOD activities. These variables included IL-1 isoform (alpha, beta, or both), IL-1 concentration (0.5, 2, 5, or 7 units IL-1 alpha/ml medium), and the presence or absence of exogenously added copper as CuO or ceruloplasmin. In addition, combining IL-1 with dexamethasone, a synthetic glucocorticoid that enhances some IL-1 actions, produced only additive, not synergistic, increases in Cu-Zn SOD activities. In conclusion, IL-1, in several different experimental protocols, raised lung fibroblast Cu-Zn SOD activity levels, but only after a 1 day lag time. Stress-induced increases in Cu-Zn SOD activity levels in vivo also tend to occur only after lag times.  相似文献   
273.
274.
Linking variation in quantitative traits to variation in the genome is an important, but challenging task in the study of life-history evolution. Linkage maps provide a valuable tool for the unravelling of such trait−gene associations. Moreover, they give insight into recombination landscapes and between-species karyotype evolution. Here we used genotype data, generated from a 10k single-nucleotide polymorphism (SNP) chip, of over 2000 individuals to produce high-density linkage maps of the great tit (Parus major), a passerine bird that serves as a model species for ecological and evolutionary questions. We created independent maps from two distinct populations: a captive F2-cross from The Netherlands (NL) and a wild population from the United Kingdom (UK). The two maps contained 6554 SNPs in 32 linkage groups, spanning 2010 cM and 1917 cM for the NL and UK populations, respectively, and were similar in size and marker order. Subtle levels of heterochiasmy within and between chromosomes were remarkably consistent between the populations, suggesting that the local departures from sex-equal recombination rates have evolved. This key and surprising result would have been impossible to detect if only one population was mapped. A comparison with zebra finch Taeniopygia guttata, chicken Gallus gallus and the green anole lizard Anolis carolinensis genomes provided further insight into the evolution of avian karyotypes.  相似文献   
275.
276.
277.
Zfy-1 and Zfy-2 are candidate genes for Tdy, the testis-determining gene in mice. We have analysed these genes in a line of XY female mice that have been shown to be mutated in Tdy. We have used Southern blot analysis to show that the Zfy genes have not undergone any major structural alterations, and have also demonstrated that both genes are transcribed normally from the mutant Y chromosome (Y) in both adult XYY testis and XY female embryonic gonads. The fact that these genes show a normal structure and expression pattern in mice with a Y chromosome known to carry a mutation in Tdy and that mutant embryos develop into females despite Zfy-1 expression, strongly supports other recent evidence that Zfy genes are not directly involved in primary testis determination.  相似文献   
278.
279.

Background  

Pelodera (Rhabditis) strongyloides is a small saprophytic nematode that lives in decaying organic matter. On rare occasions, it can invade the mammalian skin, causing a pruritic, erythematous, alopecic and crusting dermatitis on skin sites that come into contact with the ground. Diagnosis of the disease is based on case history (a dog living outdoors on damp straw bedding) with characteristic skin lesions and on the demonstration of typical larvae in skin scrapings or biopsy. Pelodera (rhabditic) dermatitis cases have been reported mainly from Central European countries and the United States.  相似文献   
280.
Colin AM Semple 《Genome biology》2001,2(6):reviews2001.1-reviews20016
The volume of human genome sequence and the variety of web-based tools to access it continue to grow at an impressive rate, but a working knowledge of certain key resources can be sufficient to get the most from your genome. This article provides an update to Genome Biology 2000, 1(4):reviews2001.1-2001.5.  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