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   17929篇
  免费   562篇
各国政治   788篇
工人农民   718篇
世界政治   1565篇
外交国际关系   654篇
法律   10715篇
中国共产党   2篇
中国政治   75篇
政治理论   3800篇
综合类   174篇
  2021年   110篇
  2020年   246篇
  2019年   292篇
  2018年   393篇
  2017年   445篇
  2016年   462篇
  2015年   323篇
  2014年   384篇
  2013年   1814篇
  2012年   446篇
  2011年   465篇
  2010年   362篇
  2009年   398篇
  2008年   471篇
  2007年   487篇
  2006年   466篇
  2005年   413篇
  2004年   422篇
  2003年   441篇
  2002年   394篇
  2001年   689篇
  2000年   638篇
  1999年   512篇
  1998年   289篇
  1997年   245篇
  1996年   205篇
  1995年   207篇
  1994年   253篇
  1993年   225篇
  1992年   342篇
  1991年   374篇
  1990年   328篇
  1989年   345篇
  1988年   320篇
  1987年   335篇
  1986年   338篇
  1985年   331篇
  1984年   284篇
  1983年   318篇
  1982年   258篇
  1981年   238篇
  1980年   181篇
  1979年   251篇
  1978年   169篇
  1977年   146篇
  1976年   130篇
  1975年   121篇
  1974年   135篇
  1973年   123篇
  1972年   113篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
Tumescent liposuction is a common cosmetic procedure that is performed as an outpatient service in physician's offices and is largely believed to be safe. The protuberant areas of the body containing the undesirable fat deposits are injected with normal saline containing lidocaine and epinephrine for pain control and hemostasis, and the waterlogged cells are suctioned out via cannula through a small incision. We recently encountered three cases in which deaths were attributed to this procedure. Two showed fat embolization in the lung and one died from fluid overload. The osmium tetroxide post-fixed lung sections showed fat emboli in the interstitial capillaries and arterioles. We reviewed the recent literature and found that pulmonary thromboemboli, fat embolization, fluid overload, and lidocaine and epinephrine intoxication are found at autopsy in many cases. Forensic pathologists responsible for determining the cause and manner of death should become familiar with the postmortem findings and risks of liposuction therapy and communicate them to their clinical colleagues and communities.  相似文献   
973.
974.
Six ninhydrin analogues containing oxygen, sulfur, and selenium substituents at the C-5 position, 5-(4-nitrophenyl)ninhydrin, and benzo[f]furoninhydrin were evaluated as fingerprint development reagents. The analogues all showed good fingerprint color development but were not superior to ninhydrin in this respect. The benzo[f]furoninhydrin complex was strongly luminescent at room temperature following zinc complexation, while the remaining analogues required cooling to -196 degrees C to produce optimum luminescence. The benzo[f]furo, nitrophenyl, and methyl selenide analogues showed the best potential as fingerprint reagents with the benzo[f]furo analogue comparing favorably with DFO.  相似文献   
975.
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   
976.
977.
978.
979.
Bile is, in certain cases, collected together with blood from different sites (heart, brain, femoral), urine and other organs or matrices. This study reports comparative results obtained from the analysis of blood and bile for different drugs found: acetaminophen, amphetamine and related compounds, several antidepressants, several benzodiazepines, cocaine and its metabolites, dextropropoxyphene and its metabolite, hydroxyzine, methadone and metabolite, morphine and codeine, levomepromazine, thioridazine, propranolol, tramadol and its metabolite. Several findings are presented: (1) There were no significant differences in the levels of the compounds among the samples of blood obtained from different sites. (2) Levels in bile are generally several fold higher than those in blood. The mean bile to blood ratios vary from about 1 (for acetaminophen, amphetamine) to about 2000 (for desmethylclobazam). (3) In certain cases (16 over 44), although the drug or its metabolite was not detected in blood from different sites, it was detected in bile. As other authors had advocated, it is very useful to ask the pathologist to take the gall bladder with its contents together with the other samples, in order that the sample of bile can be used in the comprehensive toxicological analysis and therefore be complementary to the other fluids or matrices. An additional advantage for using bile is that the concentrations of drugs or their metabolites are generally several fold higher than their blood concentrations.  相似文献   
980.
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   
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