全文获取类型
收费全文 | 16990篇 |
免费 | 496篇 |
专业分类
各国政治 | 700篇 |
工人农民 | 660篇 |
世界政治 | 1416篇 |
外交国际关系 | 582篇 |
法律 | 10233篇 |
中国共产党 | 2篇 |
中国政治 | 75篇 |
政治理论 | 3645篇 |
综合类 | 173篇 |
出版年
2020年 | 211篇 |
2019年 | 249篇 |
2018年 | 322篇 |
2017年 | 390篇 |
2016年 | 413篇 |
2015年 | 285篇 |
2014年 | 331篇 |
2013年 | 1649篇 |
2012年 | 405篇 |
2011年 | 426篇 |
2010年 | 341篇 |
2009年 | 378篇 |
2008年 | 438篇 |
2007年 | 463篇 |
2006年 | 439篇 |
2005年 | 391篇 |
2004年 | 394篇 |
2003年 | 416篇 |
2002年 | 375篇 |
2001年 | 677篇 |
2000年 | 616篇 |
1999年 | 504篇 |
1998年 | 284篇 |
1997年 | 241篇 |
1996年 | 202篇 |
1995年 | 203篇 |
1994年 | 243篇 |
1993年 | 217篇 |
1992年 | 335篇 |
1991年 | 367篇 |
1990年 | 325篇 |
1989年 | 343篇 |
1988年 | 315篇 |
1987年 | 332篇 |
1986年 | 336篇 |
1985年 | 330篇 |
1984年 | 284篇 |
1983年 | 316篇 |
1982年 | 254篇 |
1981年 | 237篇 |
1980年 | 178篇 |
1979年 | 246篇 |
1978年 | 165篇 |
1977年 | 144篇 |
1976年 | 130篇 |
1975年 | 120篇 |
1974年 | 135篇 |
1973年 | 117篇 |
1972年 | 112篇 |
1971年 | 94篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
152.
The purpose of this survey was to determine the methods of analysis being used on gunshot residue (GSR) samples in forensic science laboratories across the United States. In addition, the two general techniques of GSR analysis are compared and contrasted. Problems encountered by analysts using scanning electron microscopy/energy-dispersive X-ray analysis (SEM/EDX) are discussed. 相似文献
153.
154.
155.
Modern antitrust policy has a love hate relationshipwith non-standard contracts that can overcome market failure.On the one hand, courts have abandoned various per se rulesthat once condemned such agreements outright, concluding thatmany non-standard contracts may produce benefits that are cognizableunder the antitrust laws.1 The prospect of such benefits, itis said, compels courts to analyze these agreements under theRule of Reason, under which the tribunal determines whethera given restraint enhances or destroys competition.2 At thesame time, courts, scholars, and the enforcement agencies haveembraced methods of rule of reason analysis that are undulyhostile to such agreements.3 In particular, courts and othersare too quick to view such agreements and the market outcomesthey produce as manifestations of market power. This articleseeks to explain why these agreements are still the object ofundue hostility. 相似文献
156.
Marta Concheiro Ana de Castro Oscar Quintela Manuel Lpez-Rivadulla Angelines Cruz 《Forensic Science International Supplement Series》2005,150(2-3):221
This paper describes the analytical methodology for the determination of MDMA, MDA, MDEA and MBDB in oral fluid. After a liquid–liquid extraction, the analysis was carried out by high performance liquid chromatography (HPLC), with fluorescence detection. The detector wavelength was fixed at 285 nm for excitation and 320 nm for emission. The mobile phase, a mixture of phosphate buffer (pH = 5) and acetonitrile (75:25), and the column, Kromasil 100 C8 5 μm 250 mm × 4.6 mm, allowed good separation of the compounds in an isocratic mode in only 10 min. The method was validated and showed good limits of detection (2 ng/mL) and quantitation (10 ng/mL) for all the amphetamine derivatives. No interfering substances were detected. A stability study of these compounds in oral fluid stored at three different temperatures (−18, 4 and 20 °C) over 10 weeks was conducted, showing a time-dependent degradation of the four compounds. 相似文献
157.
158.
159.
160.
Effects of positional restraint on oxygen saturation and heart rate following exercise 总被引:1,自引:0,他引:1
D T Reay J D Howard C L Fligner R J Ward 《The American journal of forensic medicine and pathology》1988,9(1):16-18
This report assesses the effects on peripheral oxygen saturation and heart rate that positional restraint induces when a person is prone, handcuffed, and "hog-tied." Peripheral oxygen saturation and heart rate were monitored at rest, during exercise, and during recovery from exercise for 10 adult subjects. The effects of positional restraint produced a mean recovery time that was significantly prolonged. Consequently, the physiological effects produced by positional restraint should be recognized in deaths where such measures are used. 相似文献