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   568篇
  免费   20篇
各国政治   36篇
工人农民   35篇
世界政治   67篇
外交国际关系   13篇
法律   236篇
中国政治   16篇
政治理论   182篇
综合类   3篇
  2021年   5篇
  2020年   5篇
  2019年   13篇
  2018年   9篇
  2017年   12篇
  2016年   14篇
  2015年   9篇
  2014年   17篇
  2013年   102篇
  2012年   14篇
  2011年   21篇
  2010年   10篇
  2009年   8篇
  2008年   17篇
  2007年   18篇
  2006年   24篇
  2005年   19篇
  2004年   19篇
  2003年   15篇
  2002年   15篇
  2001年   18篇
  2000年   15篇
  1999年   12篇
  1998年   7篇
  1997年   11篇
  1996年   10篇
  1995年   9篇
  1994年   9篇
  1993年   12篇
  1991年   5篇
  1990年   3篇
  1989年   4篇
  1988年   5篇
  1987年   5篇
  1986年   11篇
  1985年   7篇
  1984年   11篇
  1983年   3篇
  1982年   6篇
  1981年   5篇
  1979年   10篇
  1978年   4篇
  1977年   3篇
  1976年   5篇
  1975年   3篇
  1971年   3篇
  1969年   3篇
  1968年   4篇
  1967年   5篇
  1943年   2篇
排序方式: 共有588条查询结果,搜索用时 31 毫秒
571.
A rapid method for screening drug seizure samples for 3,6-diacetylmorphine (heroin), which consists of a simple hydrolysis procedure and flow-injection analysis with two chemiluminescence reagents, is described. Before hydrolysis, 3,6-diacetylmorphine evokes an intense response with a tris(2,2'-bipyridyl)ruthenium(III) reagent (prepared by dissolving the perchlorate salt in acetonitrile), and a relatively weak chemiluminescence response with a second reagent: potassium permanganate in an aqueous acidic polyphosphate solution. However, the permanganate reagent is extremely sensitive toward the hydrolysis products of 3,6-diacetylmorphine (i.e., 6-monoacetylmorphine and morphine). Some compounds commonly found in drug laboratories may cause false positives with tris(2,2'-bipyridyl)ruthenium(III), but do not produce the markedly increased response with the permanganate reagent after the hydrolysis procedure. The combination of these two tests therefore provides an effective presumptive test for the presence of 3,6-diacetylmorphine, which we have verified with 14 samples obtained from a forensic science laboratory.  相似文献   
572.
Hypertension is a growing medical concern in the United States. With the number of Americans suffering from hypertension increasing, the use of antihypertensives such as beta-blockers is increasing as well. In fact, three beta-blockers - atenolol, metoprolol and propranolol - were among the 200 most prescribed medications in the United States in 2003. Pilots that successfully manage their hypertension can remain certified to fly. The Federal Aviation Administration currently designates approximately 8% of active pilots as "hypertensive with medication". The Civil Aerospace Medical Institute (CAMI) performs toxicological evaluation on victims of fatal aviation accidents. At CAMI beta-blockers are analyzed using gas chromatography with mass spectrometric detection. We have, however, recently developed a liquid chromatography with mass spectrometric detection (LC/MS) method for the simultaneous quantitation of three commonly prescribed beta-blockers, atenolol, metoprolol and propranolol. One advantage of our LC/MS method is the specificity provided by an ion trap MS. Utilizing an ion trap MS, we were able to conduct MS/MS and MS/MS/MS on each analyte. This method also eliminates the time-consuming and costly derivitization step necessary during GC/MS analysis. Additionally, by utilizing this novel method, any concerns about beta-blocker metabolite and/or sample matrix interference are eliminated. The limits of detection for this method ranged from 0.39 to 0.78 ng/mL and the linear dynamic range was generally 1.6-3200 ng/mL. The extraction efficiencies for each analyte ranged from 58% to 82%. This method was successfully applied to postmortem fluid and tissue specimens obtained from victims of three separate aviation accidents.  相似文献   
573.
574.
利用从猪传染性胃肠炎病毒(TGEV)Miler株(M5C)克隆建立的一株重组杆状病毒(R2-2)表达的重组TGEV钉状糖蛋白(S),建立了一种阻断酶联免疫吸附试验(ELISA)来检测猪群抗TGEV抗体。试验表明,用重组病毒R2-2接种sf9细胞(spodopterafrugiperda)所表达的重组蛋白量在接种后第72h达到最高值;该重组蛋白能与抗TGEVS蛋白A位点的单克隆抗体特异性结合。用阻断ELISA检测68份来自无TGEV感染或TGEV(Purduel5)免疫的仔猪或母猪血清,结果与TGEV蚀斑减数试验完全相符,灵敏度和特异性均为100%。同时检测来自TGEV试验免疫猪、美国部分地区猪群、我国进口猪以及我国国内猪群血清627份,阳性检出率分别为82.61%、61.62%、58.33%和29.10%;用中和试验(微量中和试验或病毒蚀斑减数试验)检测的TGE血清抗体阳性率分别为80.87%、59.60%、56.11%和30.60%,两种方法对抗TGEV抗体的检出率没有显著差异。  相似文献   
575.
This paper discusses changes in the social organization of mental institutionalization as they relate to developments in the wider social and economic environment. Despite dramatic changes in the system of inpatient psychiatric care during the last three decades, the historic division of labor between the private and the public system (with the latter treating the poor, the unemployed, and the nonwhite) has not ceased to exist. At the same time, under the influence of the postwar trend towards greater political integration of disadvantaged and marginal groups into society's central value systems, treatment of the mentally ill has become less segregated and more voluntary. An important implication of these two interacting trends--the changed legal position of the patient vis-à-vis the provider and the deteriorating economic position of the user of public psychiatric facilities--has been the exceeding irrelevance of one of the basic tenets of psychiatric care: that clinical treatment precedes social functioning. With two vignettes of chronic patients the article illustrates how symptoms and survival are fused in the contemporary, inclusionary system of care.  相似文献   
576.
577.
A basic median-voter model is developed and extended to analyze issues of economic regulation and public policy outcomes. The model is used to generate comparative static results relating changes in public-policy outcomes to changes in relative group sizes, total population, information costs, and population heterogeneity. The model is also used to explore the issue of optimal group size — the size of the special-interest group that maximizes the group's per capita public policy gains. Comparative static analysis reveals how optimal group size and gains per capita are affected by changes in population heterogeneity, the size of the total population, and relative knowledge levels.  相似文献   
578.
579.
Lewis A. Coser 《Society》1977,14(5):85-87
  相似文献   
580.
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