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   1853篇
  免费   274篇
  国内免费   4篇
  2131篇
  2022年   16篇
  2021年   32篇
  2020年   7篇
  2019年   15篇
  2018年   24篇
  2017年   23篇
  2016年   36篇
  2015年   69篇
  2014年   67篇
  2013年   77篇
  2012年   121篇
  2011年   113篇
  2010年   77篇
  2009年   70篇
  2008年   86篇
  2007年   96篇
  2006年   83篇
  2005年   84篇
  2004年   77篇
  2003年   68篇
  2002年   61篇
  2001年   68篇
  2000年   92篇
  1999年   58篇
  1998年   35篇
  1997年   34篇
  1996年   32篇
  1995年   37篇
  1994年   24篇
  1993年   18篇
  1992年   44篇
  1991年   38篇
  1990年   35篇
  1989年   32篇
  1988年   35篇
  1987年   29篇
  1986年   28篇
  1985年   24篇
  1984年   19篇
  1983年   6篇
  1982年   16篇
  1981年   9篇
  1980年   13篇
  1979年   12篇
  1978年   10篇
  1977年   8篇
  1975年   12篇
  1974年   9篇
  1973年   6篇
  1971年   5篇
排序方式: 共有2131条查询结果,搜索用时 7 毫秒
1.
A formalin-fixed paraffin-embedded (FFPE) sample usually yields highly degraded DNA, which limits the use of techniques requiring high-quality DNA, such as Infinium Methylation microarrays. To overcome this restriction, we have applied an FFPE restoration procedure consisting of DNA repair and ligation processes in a set of paired fresh-frozen (FF) and FFPE samples. We validated the FFPE results in comparison with matched FF samples, enabling us to use FFPE samples on the Infinium HumanMethylation450 Methylation array.  相似文献   
2.
A crown-of-thorns starfish control program was conducted at Grub Reef (central Great Barrier Reef) in an area (0.64 km2) which encompassed 53 individual patch reefs. During a two week period, 15 divers injected 3175 starfish with copper sulphate. The program was considered unsuccessful. Although starfish abundance had declined significantly after the control efforts, biological surveys indicated that a relatively large number of starfish remained. The surveys also indicated a general decline in the number of starfish along the reef perimeter, outside the control area. The total cost of the control program was $35 per starfish. These results have important implications for the implementation of future control programs and highlight the need to undertake before and after biological surveys to assess the effectiveness of the control efforts.  相似文献   
3.
Arundo donax L. (Poaceae) is native to Mediterranean Europe and invasive in the Rio Grande Basin of North America. Rhizomes from nine sites in France and Spain infested with a candidate control agent, the armoured scale Rhizaspidiotus donacis (Hemiptera: Diaspididae) weighed 50% less than those from nine sites without scale.  相似文献   
4.
Wives and Warriors: Women and the Military in the United States and Canada. Laurie Weinstein and Christie C. White. eds. Westport, CT: Bergin and Garvey, 1997. 252 pp.  相似文献   
5.
Old World pitcher plants (Nepenthes spp., Nepenthaceae) trapand digest invertebrate prey to derive nutrients, primarilynitrogen (N). In the majority of lowland Nepenthes species studiedto date, ants (Hymenoptera, Formicidae) are numerically thedominant prey taxon. Nepenthes albomarginata is unusual in showingan apparent bias towards the capture of termites (Isoptera).We tested the hypothesis that N. albomarginata derives N fromtermite capture, by comparison of foliar stable N isotope abundance(  相似文献   
6.
7.
Binding of a 300-kDa host cell protein (p300) is tightly correlated with the ability of the adenovirus E1A products to induce quiescent baby rat kidney cells to proliferate. We have generated rabbit polyclonal antibodies against p300 to characterize this protein further. We have found p300 to be a nuclear phosphoprotein that is actively synthesized in both quiescent and proliferating baby rat kidney cells. In partially purified mitotic cell populations, we observe a form of p300 with decreased electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels that shares a nearly identical partial proteolytic digest pattern with p300. The slower-migrating form of p300 is greatly reduced by treating immune complexes with potato acid phosphatase. The relative stability and presence of p300 even in resting cells suggests that p300 has a basal cell function, but the appearance of differentially modified forms during the cell cycle suggests the possibility that p300 function is modulated specifically in growing cells.  相似文献   
8.
Suppression of ctc promoter mutations in Bacillus subtilis.   总被引:4,自引:4,他引:0       下载免费PDF全文
C Ray  M Igo  W Shafer  R Losick    C P Moran  Jr 《Journal of bacteriology》1988,170(2):900-907
  相似文献   
9.
10.
Results of studies in mice and clinical observations in man indicate that T cell-mediated immunity is important in resistance to herpes simplex virus (HSV) infections. This study was undertaken to elucidate the viral antigen specificity of human HSV-immune T cells. Purified HSV-1 glycoproteins gB-1 and gD-1, cloned and expressed in mammalian cells, were found to stimulate proliferation of, and interleukin 2 (IL 2) production by, peripheral blood lymphocytes (PBL) of HSV seropositive individuals, indicating the presence of memory T cells to gB-1 and gD-1 in individuals with serologic evidence of immunity to HSV. Second, T cell clones, generated by stimulation of PBL with HSV-1, were found to recognize gB-1 or gD-1, as evidenced by the ability of the clones to proliferate in response to stimulation with gB-1 or gD-1 in the absence of exogenous IL 2. Third, HSV-specific T cell clones, lytic for HSV-1 or both HSV-1- and HSV-2-infected autologous target cells, were generated after stimulation of PBL with purified cloned gB-1 or gD-1. Our findings, that human HSV-specific T cells can recognize and be activated by HSV subunit antigens gB-1 or gD-1, imply that these glycoproteins play a role in human T cell-mediated immunity to HSV and support the contention that a gB-1 or gD-1 subunit vaccine may be protective in man.  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