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   9831篇
  免费   223篇
各国政治   644篇
工人农民   254篇
世界政治   581篇
外交国际关系   381篇
法律   6282篇
中国共产党   8篇
中国政治   49篇
政治理论   1748篇
综合类   107篇
  2020年   111篇
  2019年   141篇
  2018年   240篇
  2017年   232篇
  2016年   278篇
  2015年   203篇
  2014年   192篇
  2013年   981篇
  2012年   282篇
  2011年   264篇
  2010年   220篇
  2009年   246篇
  2008年   311篇
  2007年   312篇
  2006年   329篇
  2005年   223篇
  2004年   245篇
  2003年   228篇
  2002年   237篇
  2001年   419篇
  2000年   376篇
  1999年   300篇
  1998年   121篇
  1997年   110篇
  1996年   86篇
  1995年   89篇
  1994年   99篇
  1993年   86篇
  1992年   181篇
  1991年   199篇
  1990年   202篇
  1989年   203篇
  1988年   181篇
  1987年   169篇
  1986年   184篇
  1985年   151篇
  1984年   133篇
  1983年   144篇
  1982年   91篇
  1981年   91篇
  1980年   61篇
  1979年   129篇
  1978年   75篇
  1977年   63篇
  1976年   57篇
  1975年   67篇
  1974年   82篇
  1973年   80篇
  1972年   69篇
  1971年   62篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
A simple and sensitive method is described for quantitative analysis of chlorpromazine in blood, serum, urine and tissue homogenate. The chlorpromazine cation radical produced by adding perchloric acid and 2,3-dichloro-5,6-dicyano-p-benzoquinone to the sample can be detected by the ESR method at room temperature. The sensitivity limit is 10 ng, that is, 20 μl of the solution containing 0.5 μg chlorpromazine/ml. The time needed for the measurement is within 10 min. The chlorpromazine radical thus produced is very stable; for example, 95% of the radical was observed after 24 h. The advantage of this method is discussed by comparing with the ordinary spectrophotometry which requires the purification of the sample.  相似文献   
33.
This paper examines the historical development of the Australian welfare state with a view to identifying the role that Australia's federal constitutional arrangements have played in shaping that development. Theoretical paradigms have been unanimous in their prognoses: that federal states are likely to be slow in developing welfare state programmes and typically spend less on them than unitary states. But recently it has been argued that federal institutions may have a “ratchet effect” of slowing down the pace of change, irrespective of its direction. The purpose of this chronological account of significant stages in the development of the Australian welfare state is to use the unfolding of historical events — far too rich in nuance and detail to be captured in quantitative modelling — as a test‐bed for establishing whether, and, if so, to what extent, federalism has impacted on the trajectory of Australian welfare state development.  相似文献   
34.
35.
Blood previously acidified with aqueous saturated ammonium chloride solution was extracted with ethyl acetate. The dried extract was subjected to acetonitrile–hexane partition. The acetonitrile portion was analysed for the presence of acidic and neutral drugs by HPLC–DAD (200 mm×2.1 mm I.D. microbore ODS-Hypersil column) and GC–FID (25 m narrow-bore×0.25 mm I.D. HP-5 column with 0.33 μm film thickness). The protocol was found to be suitable for both clinical toxicology (including emergency toxicology) and postmortem toxicology. At least 66 drugs of interest were unequivocally identified by RRTs (HPLC) and UV spectra (DAD) match while another 12 were unequivocally identified by double RRTs match (HPLC and GC). Quantitation was facilitated by incorporating calibration blood standards in each assay batch. The five drugs most commonly encountered in clinical blood specimens (1150 cases) were: paracetamol (47.4% of the cases); chlormezanone (6.6%), theophylline (1.74%), naproxen (1.65%) and mefenamic acid (1.56%). The following drugs were detected in toxicologically significant quantities in postmortem blood specimens (245 cases): phenobarbitone (1.22% of the cases), naproxen (0.82%), chlormezanone (0.82%), theophylline (0.82%), carbamazepine (0.41%) and paracetamol (0.41%).  相似文献   
36.
Bloodstains were made with 200 microliters blood on each of 11 different common substrates to examine the effect of the stain carrier on the amount and quality of DNA recoverable. High-molecular-weight DNA was extracted from all samples after 2 days. The yield of DNA from each sample varied considerably, not only between the different stain carriers but also within a given category. With a DNA yield of up to 10 micrograms, paper, glass, nylon, wood, smooth leather and wool gave the best results, followed by blue denim and wallpaper (up to 6 micrograms), cotton fabric and carpeting (up to 4 micrograms) and suede (up to 2 micrograms). For several stain carriers the DNA-containing solution was contaminated by chemical substances, which in the case of the blue denim, suede, and carpet samples inhibited the digestion of the DNA with restriction enzymes and prevented DNA typing. The different textures of the stain carriers tested and (as for varying yields on the same carrier) the differing degree of loss of DNA during extraction and the physiological variation in the number of leukocytes in human blood are discussed as possible reasons for the wide range of variation in the amounts of DNA it was possible to extract.  相似文献   
37.
With new technically advanced methods and computers at our disposal, the efficient market hypothesis is once again being debated. At the same time, we are witnessing an unprecedented growth in both existing and new financial markets. These new markets are often in economies which have just recently embraced free market economics; we term these stock markets infant markets. Such stock markets are obviously not efficient in allocating the supply of savings to productive capital. We do not test whether or not these infant markets are informationally efficient, but instead examine whether and how they are becoming more efficient. We propose modelling the excess returns of individual securities using a multi-factor model with time-varying coefficients and generalised auto-regressive conditional heteroskedastic (GARCH) errors. If the markets are becoming more informationally efficient or the agents are learning, we would expect this to manifest itself as the time-varying coefficients becoming more stable as time increases. We test our model using data on four Bulgarian shares. First, we estimate an AR(2) model and a GARCH-M(1,1) model for the shares. Then, we estimated our AR(2) model with time varying coefficients and GARCH type errors. We find varying levels of efficiency and varying speeds of movement towards efficiency within our sample of four shares.  相似文献   
38.
39.
40.
The Tax Reform Act of 1986 rewrote the federal income tax code, bringing it closer to policy professionals' vision of what constitutes an equitable and efficient income tax. Research on tax compliance suggests the law might have affected taxpayer compliance in three ways: by reducing opportunities to overstate deductions, by changing perceptions of fairness, and by altering tax liabilities. Changes in taxpayer perceptions, attitudes, and noncompliance intentions were examined in three bodies of survey data, each containing pre-and post-reform data from independent samples of the same population. The results show an improved normative climate for taxpayer compliance and point to both the feasibility and the importance of examining the effects of substantive tax policies on taxpayer perceptions, attitudes, and behavioral intentions.  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