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   17347篇
  免费   1227篇
各国政治   699篇
工人农民   833篇
世界政治   1141篇
外交国际关系   529篇
法律   12234篇
中国共产党   2篇
中国政治   104篇
政治理论   2942篇
综合类   90篇
  2023年   79篇
  2021年   88篇
  2020年   428篇
  2019年   449篇
  2018年   563篇
  2017年   578篇
  2016年   660篇
  2015年   504篇
  2014年   534篇
  2013年   1799篇
  2012年   483篇
  2011年   503篇
  2010年   533篇
  2009年   556篇
  2008年   507篇
  2007年   500篇
  2006年   523篇
  2005年   433篇
  2004年   431篇
  2003年   357篇
  2002年   403篇
  2001年   671篇
  2000年   602篇
  1999年   480篇
  1998年   238篇
  1997年   172篇
  1996年   193篇
  1995年   189篇
  1994年   168篇
  1993年   175篇
  1992年   308篇
  1991年   311篇
  1990年   295篇
  1989年   276篇
  1988年   304篇
  1987年   261篇
  1986年   321篇
  1985年   317篇
  1984年   246篇
  1983年   226篇
  1982年   179篇
  1981年   154篇
  1980年   143篇
  1979年   221篇
  1978年   115篇
  1977年   91篇
  1975年   94篇
  1974年   124篇
  1973年   79篇
  1972年   78篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
901.
Nuclear magnetic resonance (NMR) spectroscopy was employed for the purpose of identifying samples of materials suspected of containing sodium fluoroacetate (Compound 1080). Acquisition of routine proton (1H) and carbon (13C) NMR spectra provided a straight-forward means for determining the presence of Compound 1080 in the samples and thus afforded a simple method for analysis and identification of this compound.  相似文献   
902.
Antitrust law represents the principal legal tool that the United States employs to police private markets, yet it often relegates quality and nonprice considerations to a secondary position. While antitrust law espouses the belief that vigorous competition will enhance quality as well as price, little evidence exists of the practical ability of courts to deliver on that promise. In this Article, Professors Hammer and Sage examine American health care as a vehicle for advancing understanding of the nexus among competition, quality, and antitrust law. The Article reports results of a comprehensive empirical review of judicial opinions in health care antitrust litigation between 1985 and 1999, with specific attention to courts' handling of quality and other nonprice concerns. Professors Hammer and Sage conclude that, although antitrust law cannot be expected to serve as the sole oversight mechanism for industries as complex and quality dependent as health care, courts have been successful incorporating some nonprice factors into antitrust analysis.  相似文献   
903.
The content of ethanol and acetaldehyde in the limbic cortex and reticular formation of the brain was measured by gas-liquid chromatography in lethal ethanol poisoning. The content of acetaldehyde was significantly increased in the gyrus cinguli of the brain. Lethal poisonings occurred during any stage of ethanol intoxication. The data characterizing individual ethanol tolerance were obtained, which can be used for differential diagnosis of ethanol poisoning in practical forensic medicine.  相似文献   
904.
The morphology of adrenals was studied in cases of death from total supercooling. The intensity and terms of response are different in different morphofunctional zones of the adrenal cortex. Presumably, the terms and intensity of responses of various portions of the adrenal cortex reflect the specific features of their function regulation.  相似文献   
905.
Conclusions of 41 repeated expert evaluations of craniocerebral injuries within the framework of criminal and civil cases investigation are analyzed. Some aspects of clinical and forensic medical diagnosis of lethal and nonlethal injuries to the head, evaluation of the quality of medical care, and qualification of the severity of harm to health are discussed. Causes of typical expert errors and approaches to their prevention are shown.  相似文献   
906.
907.
A sensitive analytical method was developed for quantitative analysis of delta(9)-tetrahydrocannabinol (delta(9)-THC), 11-nor-delta(9)-tetrahydrocannabinol-carboxylic acid (delta(9)-THC-COOH), cannabinol (CBN) and cannabidiol (CBD) in human hair. The identification of delta(9)-THC-COOH in hair would document Cannabis use more effectively than the detection of parent drug (delta(9)-THC) which might have come from environmental exposure. Ketamine was added to hair samples as internal standard for CBN and CBD. Ketoprofen was added to hair samples as internal standard for the other compounds. Samples were hydrolyzed with beta-glucuronidase/arylsulfatase for 2h at 40 degrees C. After cooling, samples were extracted with a liquid-liquid extraction procedure (with chloroform/isopropyl alcohol, after alkalinization, and n-hexane/ethyl acetate, after acidification), which was developed in our laboratory. The extracts were analysed before and after derivatization with pentafluoropropionic anhydride (PFPA) and pentafluoropropanol (PFPOH) using a Hewlett Packard gas chromatographer/mass spectrometer detector, in electron impact mode (GC/MS-EI). Derivatized delta(9)-THC-COOH was also analysed using a Hewlett Packard gas chromatographer/mass spectrometer detector, in negative ion chemical ionization mode (GC/MS-NCI) using methane as the reagent gas. Responses were linear ranging from 0.10 to 5.00 ng/mg hair for delta(9)-THC and CBN, 0.10-10.00 ng/mg hair for CBD, 0.01-5.00 ng/mg for delta(9)-THC-COOH (r(2)>0.99). The intra-assay precisions ranged from <0.01 to 12.40%. Extraction recoveries ranged from 80.9 to 104.0% for delta(9)-THC, 85.9-100.0% for delta(9)-THC-COOH, 76.7-95.8% for CBN and 71.0-94.0% for CBD. The analytical method was applied to 87 human hair samples, obtained from individuals who testified in court of having committed drug related crimes. Quantification of delta(9)-THC-COOH using GC/MS-NCI was found to be more convenient than GC/MS-EI. The latter may give rise to false negatives due to the detection limit.  相似文献   
908.
Prehistoric Polynesian skeletal remains are frequently being recovered in New Zealand due to the increasing pace of urbanisation. Since such material must often be reinterred quickly, it is important that the sex of individuals be determined from the remains in a relatively short time. For this purpose, discriminant function analysis was utilised for sex determination of prehistoric adult New Zealand Polynesian tali (24 males and 27 females). Five measurements were taken and subjected to Statistical Package for the Social Sciences (SPSS) discriminant function analysis. For the discriminant functions derived, accuracy of sex determination ranged from 85.1 to 93.3%. Reduction in error over random assignment by sex ranged from 70 to 87%.  相似文献   
909.
Allele frequencies for the three STR loci included in the GenePrint CTT multiplex system (HUMTH01, HUMTPOX, HUMCSF1PO) have been determined for the four major sub-populations of New Zealand.  相似文献   
910.
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