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   71篇
  免费   0篇
系统科学   7篇
现状及发展   11篇
研究方法   10篇
综合类   43篇
  2013年   1篇
  2012年   5篇
  2011年   8篇
  2010年   1篇
  2008年   10篇
  2007年   3篇
  2006年   1篇
  2005年   5篇
  2004年   3篇
  2003年   3篇
  2002年   5篇
  2001年   1篇
  2000年   1篇
  1998年   2篇
  1994年   1篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1981年   1篇
  1979年   2篇
  1978年   1篇
  1975年   2篇
  1974年   1篇
  1973年   2篇
  1970年   3篇
  1969年   1篇
  1966年   2篇
  1965年   2篇
排序方式: 共有71条查询结果,搜索用时 171 毫秒
11.
12.
Chain initiation by reovirus RNA transcriptase in vitro   总被引:3,自引:0,他引:3  
D H Levin  G Acs  S C Silverstein 《Nature》1970,227(5258):603-604
  相似文献   
13.
14.
Trans-kingdom promiscuity   总被引:6,自引:0,他引:6  
R S Sikorski  W Michaud  H L Levin  J D Boeke  P Hieter 《Nature》1990,345(6276):581-582
  相似文献   
15.
Lately, society has pressed for more direct societal relevance of social research. The argument of this special issue is that engaged research is an answer to the demand for a social science that matters. We define engaged research as a praxis where researchers actively engage in a social field in the pursuit of solving important local problems, while at the same time combining this with a scientific knowledge generation process. In other words, we discuss the conditions for research when researchers “go native” to solve problems and reflect along with participants. We have been able to find several sources of arguments supporting such a research strategy, but our search for methodological guidance on how to act as an engaged researcher has been in vain. What does it take for a researcher to do engaged research? The set of articles in this special issue all address certain aspects of this challenge. Some discuss the researcher’s path towards deep field engagement, whereas others discover various challenges and skills involved in engagement, and the task of developing scientific knowledge based on engaged research.  相似文献   
16.
Inflammatory bowel disease (IBD) typically manifests as either ulcerative colitis (UC) or Crohn's disease (CD). Systematic identification of susceptibility genes for IBD has thus far focused mainly on CD, and little is known about the genetic architecture of UC. Here we report a genome-wide association study with 440,794 SNPs genotyped in 1,167 individuals with UC and 777 healthy controls. Twenty of the most significantly associated SNPs were tested for replication in three independent European case-control panels comprising a total of 1,855 individuals with UC and 3,091 controls. Among the four consistently replicated markers, SNP rs3024505 immediately flanking the IL10 (interleukin 10) gene on chromosome 1q32.1 showed the most significant association in the combined verification samples (P = 1.35 x 10(-12); OR = 1.46 (1.31-1.62)). The other markers were located in ARPC2 and in the HLA-BTNL2 region. Association between rs3024505 and CD (1,848 cases, 1,804 controls) was weak (P = 0.013; OR = 1.17 (1.01-1.34)). IL10 is an immunosuppressive cytokine that has long been proposed to influence IBD pathophysiology. Our findings strongly suggest that defective IL10 function is central to the pathogenesis of the UC subtype of IBD.  相似文献   
17.
At present, transgenes in Caenorhabditis elegans are generated by injecting DNA into the germline. The DNA assembles into a semistable extrachromosomal array composed of many copies of injected DNA. These transgenes are typically overexpressed in somatic cells and silenced in the germline. We have developed a method that inserts a single copy of a transgene into a defined site. Mobilization of a Mos1 transposon generates a double-strand break in noncoding DNA. The break is repaired by copying DNA from an extrachromosomal template into the chromosomal site. Homozygous single-copy insertions can be obtained in less than 2 weeks by injecting approximately 20 worms. We have successfully inserted transgenes as long as 9 kb and verified that single copies are inserted at the targeted site. Single-copy transgenes are expressed at endogenous levels and can be expressed in the female and male germlines.  相似文献   
18.
Basal-like breast cancer (BBC) is a subtype of breast cancer with poor prognosis. Inherited mutations of BRCA1, a cancer susceptibility gene involved in double-strand DNA break (DSB) repair, lead to breast cancers that are nearly always of the BBC subtype; however, the precise molecular lesions and oncogenic consequences of BRCA1 dysfunction are poorly understood. Here we show that heterozygous inactivation of the tumor suppressor gene Pten leads to the formation of basal-like mammary tumors in mice, and that loss of PTEN expression is significantly associated with the BBC subtype in human sporadic and BRCA1-associated hereditary breast cancers. In addition, we identify frequent gross PTEN mutations, involving intragenic chromosome breaks, inversions, deletions and micro copy number aberrations, specifically in BRCA1-deficient tumors. These data provide an example of a specific and recurrent oncogenic consequence of BRCA1-dependent dysfunction in DNA repair and provide insight into the pathogenesis of BBC with therapeutic implications. These findings also argue that obtaining an accurate census of genes mutated in cancer will require a systematic examination for gross gene rearrangements, particularly in tumors with deficient DSB repair.  相似文献   
19.
During the late years there has been an ever-increasing focus on the possibilities to change the building process to raise quality on the final building products as well as the activities of actors involved in the building process. One reason for this interest is the new opportunities evolving due to introduction of advanced information and communication technology (ICT). The paper focuses on creative changes of the building process powered by user driven innovation activities. An overview of existing user driven innovation methodologies is given as well experiences from the ongoing Virtual Innovation in Construction (VIC) project. One important driving force for change is the opportunity for users to develop and articulate real needs concerning for example different functionalities of a building and its parts, but also on artifacts supporting the actual needs capture and requirements formulation during building design. A general methodological framework and meta ontology for Virtual Innovation in Construction is presented as well as findings from implementation of the method.  相似文献   
20.
The mineralogical and elemental compositions of the martian soil are indicators of chemical and physical weathering processes. Using data from the Mars Exploration Rovers, we show that bright dust deposits on opposite sides of the planet are part of a global unit and not dominated by the composition of local rocks. Dark soil deposits at both sites have similar basaltic mineralogies, and could reflect either a global component or the general similarity in the compositions of the rocks from which they were derived. Increased levels of bromine are consistent with mobilization of soluble salts by thin films of liquid water, but the presence of olivine in analysed soil samples indicates that the extent of aqueous alteration of soils has been limited. Nickel abundances are enhanced at the immediate surface and indicate that the upper few millimetres of soil could contain up to one per cent meteoritic material.  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