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   3959篇
  免费   110篇
各国政治   212篇
工人农民   127篇
世界政治   241篇
外交国际关系   135篇
法律   2683篇
中国政治   40篇
政治理论   608篇
综合类   23篇
  2024年   42篇
  2023年   155篇
  2021年   56篇
  2020年   49篇
  2019年   48篇
  2018年   65篇
  2017年   83篇
  2016年   86篇
  2015年   62篇
  2014年   76篇
  2013年   377篇
  2012年   103篇
  2011年   115篇
  2010年   80篇
  2009年   80篇
  2008年   102篇
  2007年   117篇
  2006年   124篇
  2005年   108篇
  2004年   101篇
  2003年   109篇
  2002年   96篇
  2001年   174篇
  2000年   146篇
  1999年   91篇
  1998年   39篇
  1997年   33篇
  1996年   29篇
  1994年   31篇
  1993年   27篇
  1992年   74篇
  1991年   85篇
  1990年   76篇
  1989年   96篇
  1988年   90篇
  1987年   76篇
  1986年   86篇
  1985年   81篇
  1984年   43篇
  1983年   51篇
  1982年   30篇
  1981年   36篇
  1979年   32篇
  1977年   29篇
  1975年   32篇
  1974年   33篇
  1973年   34篇
  1972年   33篇
  1971年   25篇
  1969年   25篇
排序方式: 共有4069条查询结果,搜索用时 15 毫秒
221.
A total of 743 lethal outcomes of thromboembolytic complications of trauma, diseases and certain pathological conditions as observed in 1999-2001 and in the three quarters of 2002 were studied. The undertaken analysis confirmed two factors provoking the pathological thrombosis, i.e. 1. Pathological changes observed in the surface vascular wall preconditioned by mechanical damages, atherosclerotic process and aging; and 2. A slower blood flow due to an impaired blood circulation, a forced positioning and to hypodynamics. While deciding on a possibility of a direct cause-effect relation between past traumas, surgeries, poisonings and death of thromboembolism of the pulmonary arteries (TEPA), such relation can be mentioned only on rare occasions. It is more often the case that an indirect, mediated relationship is found, when TERA evolves due to an unfavorable combination of risk factors, i.e. a forced immobility, changing coagulated blood system, impaired blood vessels etc.  相似文献   
222.
The results of histomorphometric examinations of the pancreas in drug- and alcohol-addiction as well as in acute intoxications are described. They show that, in chronic alcoholic intoxication as compared with opiomania, there are more pronounced interlobular sclerosis and lipomatosis, which is manifested by an enlarged middle lobe of the stroma (containing fat and connective tissue fibers), by a higher density of islands of Langerhans and by their higher sectional area. Autolysis and edema of the stroma are more severe in an acute intoxication with drugs than in other cases of fatal outcome. A possibility is demonstrated to differentiate between various types of the so-called long-term exogenous intoxication and to discriminate between different types of thanatogenesis typical of various cases of acute intoxications. Data are presented that demonstrate the advantage of the quantitative analysis of histological preparations over the qualitative one.  相似文献   
223.
Eighteen cadavers of persons, who died of acute and chronic alcohol and drug intoxication (ephedron-addiction), were used to study the changes in the spinal nerve plexuses and external genitals. The activity of acetylcholinesterase and of NADPH-diaphorase was determined histochemically; the adrenergic nerve fibers were detected by a glyoxyl-acid technique. Rectified changes in the relative density of adrenal-cholinergic- and nitroxydergic structures and in the activity of mediators in different intoxications were found. The chronic intoxication by alcohol and ephedron was accompanied by a reduced activity of enzymes involved in the metabolism of acetylcholine, nitric oxide and catecholamines. A lower density was observed in the nerve fibers that contained the examined substances. The results can be used as an additional criterion in evaluating the male sexual-function status.  相似文献   
224.
225.
A possibility was considered to isolate, by using dimethylformamide, 2.4-dinitrophenol, 2-amino-4-nitrophenol and 4-oxid-diphenyl from a biological-origin object. A method of extraction with subsequent chromatography in thin silicon-gel layer was used to purify the isolates from biological materials. The designed technique provides for identifying and for quantitatively defining the discussed phenol structures contained in the isolates from the liver tissue of corpses and human blood.  相似文献   
226.
227.
228.
Variation in the mitochondrial DNA (mtDNA) control region as detected by sequence-specific oligonucleotide (SSO) probes is described for 2282 individuals from African-American, European-American, and Hispanic subpopulations from five broadly defined regions of North America (Northeast, Southeast, Central, Northwest, Southwest). Population diversity estimates were uniformly high for all subpopulations and for each major ethnic group. Only the Pennsylvania Hispanic group was remarkable with respect to its mitochondrial DNA types, having both six low frequency population specific types (ranging from 1.2-8.6%) and three high frequency shared types (10-20% each). There was no statistically significant subpopulation heterogeneity present within any of the three major groups at either the subpopulation level or the regional level (p > 0.01). However, statistically significant heterogeneity was measured when comparing the three major groups to each other, with the variance component attributable to this large division accounting for 18.60% of the total variance (p < 0.001). Overall mtDNA is a satisfactory forensic typing locus within broadly defined African-American, European-American, and Hispanic groups from North America, based on the high diversity estimates and absence of heterogeneity, as characterized by SSO typing.  相似文献   
229.
Medical training in the United States often takes the form of a grueling endurance test in which patients are often those most at risk. This Article discusses sleep deprivation among resident physicians in the United States with an eye towards resolving the problem through legal channels. It analyzes the effects of sleep deprivation on resident physicians, with subsequent discussion of the implications for patient care and medical training. Next, it makes comparisons to medical training in other developed nations, as well as regulations that exist in the airline and trucking industries, where public safety is a principal concern. Furthermore, this Article discusses proposals to mend the dilemmas created by sleep-deprived resident physicians through statutory and regulatory reform, deterrence by way of tort law, and unionization or collective bargaining.  相似文献   
230.
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