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   14550篇
  免费   211篇
各国政治   515篇
工人农民   1289篇
世界政治   593篇
外交国际关系   522篇
法律   8845篇
中国政治   48篇
政治理论   2913篇
综合类   36篇
  2023年   47篇
  2020年   101篇
  2019年   118篇
  2018年   1403篇
  2017年   1344篇
  2016年   1170篇
  2015年   162篇
  2014年   147篇
  2013年   662篇
  2012年   345篇
  2011年   1073篇
  2010年   1115篇
  2009年   718篇
  2008年   873篇
  2007年   835篇
  2006年   177篇
  2005年   192篇
  2004年   323篇
  2003年   297篇
  2002年   153篇
  2001年   269篇
  2000年   259篇
  1999年   191篇
  1998年   89篇
  1997年   86篇
  1996年   94篇
  1995年   94篇
  1994年   95篇
  1993年   67篇
  1992年   147篇
  1991年   136篇
  1990年   164篇
  1989年   155篇
  1988年   164篇
  1987年   146篇
  1986年   133篇
  1985年   132篇
  1984年   107篇
  1983年   96篇
  1982年   70篇
  1981年   63篇
  1980年   52篇
  1979年   71篇
  1978年   59篇
  1977年   48篇
  1975年   39篇
  1974年   49篇
  1973年   37篇
  1971年   39篇
  1970年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Pulmonary thromboembolism is an often fatal complication of venous thrombosis. Any component or combination of the components composing Virchow's triad (venostasis, hypercoagulability, and endothelial damage) increases the propensity for a thrombophilic state. Hypercoagulable states may be inherited or acquired. While the etiology in many cases may be evident either on physical examination or on evaluation of the decedent's medical history, this is often not the case. We conducted a retrospective study of cases presenting to the Jefferson County Coroner/Medical Examiner's Office in Birmingham, Alabama, who were given a diagnosis of pulmonary embolism. A search of cases within the past 23 years yielded 81 cases. An underlying cause was determined in 70 cases (86%). The remaining 11 (14%) cases had no identifiable cause. We believe that a number of these cases may represent an underlying thrombophilic disorder. Since these disorders may be of an inherited or acquired nature, the determination of an etiology may be relevant to the decedent's family. Postmortem blood analyses may in selected cases be useful and appropriate for the detection of some of these disorders. However, such analyses are not practical in all cases, with each case having to be evaluated on its own merits.  相似文献   
972.
This study explored the effects of judges' personal characteristics (gender, race, age, and political affiliation) and case characteristics on the outcomes of federal cases of hostile environment sexual harassment. Results revealed that even after controlling for the effects of relevant case characteristics (e.g., severity of the harassment), judges' personal characteristics influenced case outcomes. Specifically, younger judges and Democrat judges were more likely to find for the plaintiff (the alleged victim of harassment). The probability that the decision would favor the plaintiff was only 16% when the case was heard by an older judge but 45% when heard by a younger judge. The probability that the decision would favor the plaintiff was only 18% when the case was heard by a judge who had been appointed by a Republican president but 46% when the judge had been appointed by a Democrat president.  相似文献   
973.
A 20 year-old male driver of a heavy duty crane, employed in an industry located in an industrial area on the outskirts of Delhi was fatally injured while repositioning an ill-fitted locking rim of a crane tyre (Fig. 1). The inner tube of the crane tyre had accidentally burst, dislodging the loose iron-locking rim, which hit the individual with a great force resulting in multiple injuries. He died on his way to the hospital.  相似文献   
974.
Classification of seized methamphetamine by impurity profiling can provide very useful information in criminal investigations of drug traffic routes, sources of supply and relationships between seizures. The aim of this study is to improve and develop an analytical method for detecting impurities such as starting materials and by-products in illegally prepared methamphetamine.HCl samples. A 50mg sample of methamphetamine.HCl was dissolved in 1 ml of buffer solution (four parts 0.1M phosphate buffer pH 7.0 and one part 10% Na2CO3). Impurities were extracted with 0.5 ml of ethyl acetate containing four internal standards (ISs) (n-decane, n-pentadecane, n-nonadecane and n-hexacosane) and analyzed by gas chromatography (GC) using a flame ionization detector (FID) on a DB-5 capillary column (0.32 mmi.d. x 30 m, film thickness 1.0 microm). The use of a middle-bore column offered better separation of the impurity peaks. The correction of the retention times of impurity peaks with four ISs made peak identification very accurate for subsequent data processing. Twenty-four characteristic peaks were selected for comparison and similarity and/or dissimilarity between samples, and the data were evaluated by the Euclidean distance of the relative peak areas after logarithmic transformation. The results indicate that the present method would be useful for methamphetamine impurity profiling.  相似文献   
975.
The recreational use of amphetamine derivatives has become increasingly popular in our country in past recent years. Their use is especially common among young people participating in dance parties known as "raves." As a direct consequence of their increased use, the number of fatal cases in which these compounds have been involved have increased dramatically since the second half of the last decade. In our laboratory, we have registered 25 cases related to amphetamine derivatives use since 1996. Three of them were deeply studied and the results obtained are presented in this paper. This information may be useful for the interpretation of the results obtained in toxicological analysis in the cases in which death may be attributed to MDMA use.  相似文献   
976.
Frequency of analytical characteristics is best estimated on glass recovered at random. However, as such data were not available to us, we decided to use control windows for this estimation. In order to use such a database, one has to establish that the recovered fragment comes from a window. Therefore, elemental analysis was used both for classification and discrimination of glass fragments. Several articles have been published on the subject, but most methods alter the glass sample. The use of non destructive energy dispersive X-ray microfluorescence (microXRF) for the analysis of small glass fragments has been evaluated in this context. The refractive index (RI) has also been measured in order to evaluate the complementarity of techniques. Classification of fragments has been achieved using Fisher's linear discriminant analysis (LDA) and neural networks (NN). Discrimination was based on Hotelling's T2 test. Only pairs that were not differentiated by RI followed by the Welch test were studied. The results show that neural network and linear discriminant analysis using qualitative and semi-quantitative data establishes a classification of glass specimens with a high degree of reliability. For discrimination, 119 windows collected from crime scene were compared: using RI it was possible to distinguish 6892 pairs. Out of 129 remaining pairs, 112 were distinguished by microXRF.  相似文献   
977.
978.
Fibronectin, MRP8, MRP14 and defensin were detected immunohistochemically in 46 surgically treated, fresh (hours old) human wounds and in wounds of 13 individuals who died immediately from fatal trauma (airplane crashes or train rollovers). In immediate fatal trauma, it was not possible to detect fibronectin outside of bleeding areas nor could inflammatory cells be visualized in the interstitium using MRP8, MRP14, or defensin antibodies. Fibronectin staining could be regularly demonstrated in wounds at least 20 min-old. Granulocytic infiltrates limited to the perivasal space could be detected 20-30 min after infliction of the wound expressing MRP8, MRP14 and defensin. It was also possible to detect fibronectin networks and MRP8-, MRP14-, and defensin-positive granulocytes and macrophages in particular wounds up to 30 days-old. No differences between the expression of MRP8 and MRP14 could be demonstrated in the wounds, the majority of which were only several hours old. As wound age increased, the number of defensin-positive granulocytes detected decreased. The immunohistochemical detection of fibronectin is a useful way to demonstrate vitality in fresh wounds, beginning about 20-30 min post-trauma. However, detection of MRP8, MRP14 and defensin provides no advantage over the routine histological detection of granulocytes and macrophages in wounds under 1-2 days old.  相似文献   
979.
Evaluation of links in heroin seizures   总被引:4,自引:0,他引:4  
  相似文献   
980.
Allele frequencies for eight tetranucleotide short tandem repeat (STR) loci-CSF1PO, TPOX, TH01, F13A01, FESFPS, vWA, F13B, LPL-were obtained from a population sample of 105-122 unrelated individuals born in Transylvania and Banat (Romania).  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