全文获取类型
收费全文 | 14513篇 |
免费 | 441篇 |
专业分类
各国政治 | 509篇 |
工人农民 | 645篇 |
世界政治 | 920篇 |
外交国际关系 | 432篇 |
法律 | 9196篇 |
中国共产党 | 35篇 |
中国政治 | 150篇 |
政治理论 | 2901篇 |
综合类 | 166篇 |
出版年
2020年 | 201篇 |
2019年 | 194篇 |
2018年 | 283篇 |
2017年 | 340篇 |
2016年 | 370篇 |
2015年 | 316篇 |
2014年 | 302篇 |
2013年 | 1305篇 |
2012年 | 360篇 |
2011年 | 388篇 |
2010年 | 309篇 |
2009年 | 369篇 |
2008年 | 447篇 |
2007年 | 456篇 |
2006年 | 445篇 |
2005年 | 413篇 |
2004年 | 407篇 |
2003年 | 350篇 |
2002年 | 343篇 |
2001年 | 505篇 |
2000年 | 468篇 |
1999年 | 366篇 |
1998年 | 218篇 |
1997年 | 159篇 |
1996年 | 178篇 |
1995年 | 168篇 |
1994年 | 176篇 |
1993年 | 168篇 |
1992年 | 281篇 |
1991年 | 320篇 |
1990年 | 307篇 |
1989年 | 276篇 |
1988年 | 298篇 |
1987年 | 274篇 |
1986年 | 316篇 |
1985年 | 292篇 |
1984年 | 235篇 |
1983年 | 231篇 |
1982年 | 149篇 |
1981年 | 167篇 |
1980年 | 141篇 |
1979年 | 144篇 |
1978年 | 141篇 |
1977年 | 105篇 |
1976年 | 96篇 |
1975年 | 108篇 |
1974年 | 121篇 |
1973年 | 129篇 |
1972年 | 86篇 |
1969年 | 84篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
All records from the Danish Medicolegal Council concerning drivers suspected for drug influences were examined for the 5 year period 1981-1985. 461 records were included, 62 women and 399 men. In 250 cases drugs from more than one of ten groups had been taken thus making 786 combinations of drug/driving. The major drug group was benzodiazepines, accounting for 65% of all drug intake. Opioids also contributed substantially, found in 38% of the cases. A traffic accident had occurred in 180 (39%) of the records. Drivers who had been taking antidepressives were involved in an accident in 67%, significantly above the mean. For benzodiazepines, the corresponding percentage was 43%, while for opioids it was only 23%, significantly below the mean. This striking difference has been demonstrated in most of the studies concerning drugs in traffic. It may support the hypothesis that opioids do not necessarily make driving dangerous, as do antidepressives, barbiturates and especially benzodiazepines. 相似文献
103.
104.
Quadratic pieces of fleece measuring 16 mm2 were soaked with 10 different blood-samples in the dilution steps of 1:1, 1:10, 1:100, 1:1000, respectively, and were tested in blood group typing and identification tests of forensic serology. The above spezified dilutions correspond with 5 microliters, 0.5 microliter, 0.05 microliter and 0.005 microliter of blood, respectively. The detection limit of the microspectrometric test for blood was the dilution 1:10, of the porphyrine test a dilution above 1:100, whereas the preliminary test for blood (peroxidase) succeeded always up to a dilution of 1:1000 and the species determination by the radial immunodiffusion test in agar gels succeeded in most cases op to a dilution of 1:1000. The detection limit of the anti-human globulin inhibition test was between the dilution steps 1:10 and 1:100 when non-titrated and undiluted anti-human globulin serum was used. Gc- and ABO-grouping were possible up to a dilution of 1:100 and were thus the most sensitive grouping systems. Phenotyping of the enzyme-systems and the Gm/Km-system usually required stains with considerably higher blood concentrations i.e. stains of undiluted blood. 相似文献
105.
Steffen L. Lauritzen Julia Mortera 《Forensic Science International Supplement Series》2002,130(2-3):125-126
We derive a simple inequality for the probability of observing a given DNA profile when assuming a fixed number of unknown persons have contributed to the mixed stain. We then show how this inequality can be used to obtain an upper bound for the number of unknown contributors needed to be considered. 相似文献
106.
行政立法程序既应追求行政行为的效率,又应追求立法行为的民主。在民主与效率之间,行政立法程序应以民主为更高的价值追求。针对我国目前的法律、法规及行政立法的现状,在行政立法准备制定阶段应建立更为民主的制度,但同时也不能忽略行政立法程序的效率。 相似文献
107.
This analysis reveals that traditional market power measuresare biased under the conditions of multi-market participationand demand interdependence. Specifically, when complementary(substitutable) demands dominate, traditional market power measuresare biased upward (downward). A similar bias carries over tothe evaluation of mergers. To wit, mergers that simultaneouslyincrease market concentration and multi-market participationcan result in lower prices even in the absence of merger economies.It follows that merger guidelines that place undue emphasison market concentration can lead policymakers to block (approve)mergers that enhance (diminish) consumer welfare. 相似文献
108.
Telecommunications regulation has experienced a fundamentalshift from rate regulation to increased reliance on compelledaccess, perhaps best exemplified by the Telecommunications Actof 1996's imposition of no fewer than four new access requirements.Unfortunately, each access requirement is governed by a separateset of rules for determining both the scope and the price ofaccess. The resulting ad hoc regime has created difficult definitionalproblems and opportunities for regulatory arbitrage. In thisarticle we propose a system inspired by the discipline of mathematicsknown as graph theory that integrates all of the different formsof access into a single analytical framework. This system separatesdifferent access regimes into five categories: (1) retail access,(2) wholesale access, (3) interconnection access, (4) platformaccess, and (5) unbundled access. It also provides insightsinto how each type of access complicates the already difficultproblems of network configuration and management and introducesinefficient biases into decisions about network capacity anddesign. The approach we propose also provides insights intothe transaction cost implications of the different types ofaccess. Drawing on the Coasean theory of the firm, our approachexamines the tradeoffs between internal governance costs andthe external transaction costs of providing access to offera theory of network boundaries. This framework shows how accessregulation distorts networks' natural boundaries and providesa basis for evaluating whether private ordering through marketswould lead to more efficient network design. 相似文献
109.
Eighteen external quality assessment (proficiency testing) samples were prepared from client specimens collected with the Intercept® oral fluid collection device and by spiking drug-free oral fluid. Samples were circulated in pairs at quarterly intervals to 13 UK and USA based laboratories for analysis by a panel of OraSure micro-plate Intercept® enzyme immunoassay kits and hyphenated mass spectrophotometric techniques. During the survey, there was a single case of non-specificity in a false report for methadone. The major errors were of lack of sensitivity relative to the concentration thresholds specified for the immunoassays. The sensitivity for overall ‘present’/‘not found’ reports calculated as true positives/(true positives + false negatives) were for the amfetamine specific assay 50%, methyl-amfetamines 93%, barbiturates 64%, cannabinoids 73%, cocaine and metabolites 100%, benzodiazepines 69%, methadone 95%, opiates 79% (opiates excluding oxycodone 93%), phencyclidine 93% and human gamma-globulin 97%. A small number of the sensitivity errors were attributable to errors in chromatographic confirmation techniques. 相似文献
110.
This study investigated the influence of an authority figure on eyewitness identification. Participants watched a staged crime
and then were administered a photo lineup by either an authority (policeman) or non-authority figure (civilian). Participants
in the authority condition were more likely to choose a lineup member than those in the non-authority condition. There was
no effect of authority, however, on the accuracy of the identification decisions. The lack of a deleterious effect suggests
that the presence of a police officer during identification procedures does not create an unduly suggestive situation or have
undesirable effects on eyewitness identification decisions. Although witnesses' choosing behaviors did not increase the rate
of identification errors, the effect of the administrator's authority on choosing was reduced when unbiased instructions (vs.
biased instructions) were presented to the witnesses. Thus, support was found for the use of neutral instructions during eyewitness
identification procedures. 相似文献