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   10015篇
  免费   113篇
  国内免费   3篇
各国政治   318篇
工人农民   1139篇
世界政治   305篇
外交国际关系   391篇
法律   5383篇
中国共产党   70篇
中国政治   286篇
政治理论   2022篇
综合类   217篇
  2023年   19篇
  2022年   12篇
  2021年   83篇
  2020年   57篇
  2019年   58篇
  2018年   1347篇
  2017年   1292篇
  2016年   1072篇
  2015年   148篇
  2014年   94篇
  2013年   203篇
  2012年   270篇
  2011年   995篇
  2010年   1097篇
  2009年   643篇
  2008年   825篇
  2007年   807篇
  2006年   109篇
  2005年   169篇
  2004年   241篇
  2003年   223篇
  2002年   93篇
  2001年   41篇
  2000年   35篇
  1999年   13篇
  1998年   16篇
  1997年   15篇
  1996年   23篇
  1995年   32篇
  1994年   24篇
  1993年   5篇
  1992年   2篇
  1991年   3篇
  1990年   2篇
  1989年   4篇
  1988年   3篇
  1987年   2篇
  1986年   1篇
  1984年   10篇
  1983年   9篇
  1982年   5篇
  1979年   5篇
  1978年   8篇
  1977年   9篇
  1976年   1篇
  1972年   2篇
  1968年   1篇
  1967年   1篇
  1966年   1篇
  1964年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
A method for the simultaneous determination of cocaine (COC) and cocaethylene (CE) in human hair was developed, using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) as analytical technique to identify and quantify the drugs. Selected ion monitoring (SIM) mode was used to obtain higher sensitivity. The deuterated-labeled analogues were used as internal standards. The detector response was linear for the drugs studied over the range 0.4-15 ng/mg, with correlation coefficients higher than 0.995. The coefficients of variation oscillated between 0.65% and 14.18% and the accuracy was in the range from 0.73% to 11.20%. The limits of quantitation and detection were found to be acceptable. Finally, this method was applied to 15 hair samples from cocaine users, obtaining positive results in all cases. The mean concentrations were 5.39 ng/mg (range: 0.43-8.98 ng/mg) for cocaine and 1.11 ng/mg (range: 0.42-2.23 ng/mg) for cocaethylene.  相似文献   
962.
Allele frequencies for 15 short tandem repeats (STRs) autosomal loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818 and FGA, included in the AmpFLSTR Identifiler, Applied Biosystems) were studied in the city of Maracaibo, Venezuela and were compared with other published Latin-American populations for the same loci. Population and forensic parameters were estimated.  相似文献   
963.
964.
965.
966.
967.
968.
969.
In recent years, development agencies (DAs) have focused their activities on consulting projects rather than on financing turnkey projects when assisting emerging markets. The main reason is that the implementation of consulting projects is likely to be connected with an intensive knowledge transfer from developed to emerging markets. Training of local employees and cooperation with local firms are necessary elements to make the transfer effective. The empirical statistics shows training and cooperation to be more frequent in consulting projects financed by DAs as compared to commercial projects. According to theory and experience, training should be included in projects in the least developed host countries, whereas local cooperation should be more frequent, the higher is the development level of the host country. However, DAs do not follow these rules of thumb in a convincing way. A policy implication of the paper is therefore that DAs should better organize and plan the contents of their consulting projects.
Roger SvenssonEmail:
  相似文献   
970.
Several recent studies show European university scientists contributing far more frequently to company-owned patented inventions than they do to patents owned by universities or by the academic scientists themselves. Recognising the significance of this channel for direct commercialisation of European academic research makes it important to understand its response to current Bayh-Dole inspired reforms of university patenting rights. This paper studies the contribution from university scientists to inventions patented by dedicated biotech firms (DBFs) specialised in drug discovery in Denmark and Sweden, which in this respect share a number of structural and historic characteristics. It examines effects of the Danish Law on University Patenting (LUP) effective January 2000, which transferred to the employer university rights to patents on inventions made by Danish university scientists alone or as participants in collaborative research with industry. Sweden so far has left property rights with academic scientists, as they also were in Denmark prior to the reform. Consequently, comparison of Danish and Swedish research collaboration before and after LUP offers a quasi-controlled experiment, bringing out effects on joint research of university IPR reform. In original data on all 3,640 inventor contributions behind the 1,087 patents filed by Danish and Swedish DBFs 1990–2004, Difference-in-Difference regressions uncover notable LUP-induced effects in the form of significant reductions in contributions from Danish domestic academic inventors, combined with a simultaneous substitutive increase of non-Danish academic inventors. A moderate increase in academic inventions channelled into university owned-patents does appear after LUP. But the larger part of the inventive potential of academia, previously mobilised into company-owned patents, seems to have been rendered inactive as a result of the reform. As a likely explanation of these effects the paper suggests that exploratory research, the typical target of joint university-DBF projects in drug discovery, fits poorly into LUP’s requirement for ex ante allocation of IPR. The Pre-LUP convention of IPR allocated to the industrial partner in return for research funding and publication rights to the academic partner may have offered more effective contracting for this type of research. There are indications that LUP, outside the exploratory agenda of drug discovery, offers a more productive framework for inventions requiring less complicated and uncertain post-discovery R&D.
Finn ValentinEmail:
  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