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   7094篇
  免费   678篇
各国政治   755篇
工人农民   247篇
世界政治   789篇
外交国际关系   510篇
法律   3069篇
中国政治   83篇
政治理论   2227篇
综合类   92篇
  2023年   39篇
  2022年   19篇
  2021年   65篇
  2020年   121篇
  2019年   269篇
  2018年   291篇
  2017年   335篇
  2016年   396篇
  2015年   274篇
  2014年   276篇
  2013年   1411篇
  2012年   266篇
  2011年   264篇
  2010年   254篇
  2009年   195篇
  2008年   267篇
  2007年   278篇
  2006年   250篇
  2005年   210篇
  2004年   221篇
  2003年   176篇
  2002年   179篇
  2001年   110篇
  2000年   113篇
  1999年   118篇
  1998年   94篇
  1997年   101篇
  1996年   85篇
  1995年   76篇
  1994年   82篇
  1993年   88篇
  1992年   73篇
  1991年   68篇
  1990年   71篇
  1989年   58篇
  1988年   70篇
  1987年   43篇
  1986年   54篇
  1985年   43篇
  1984年   47篇
  1983年   36篇
  1982年   30篇
  1981年   37篇
  1980年   24篇
  1979年   24篇
  1978年   25篇
  1977年   20篇
  1976年   15篇
  1975年   14篇
  1974年   32篇
排序方式: 共有7772条查询结果,搜索用时 15 毫秒
991.
Since 1999, women have democratically won the presidency eight times in Latin America and have named hundreds of ministers. This study argues that under certain conditions, presidentas are more likely than male presidents to improve women's cabinet representation. Two mechanisms, presidenta mandates and gendered networks, appear to drive the relationship. Furthermore, because the pool of ministerial candidates is shallower for women than for men, presidentas are most likely to advance women's representation in cabinets at the beginning of their term and for “feminine” ministries. A case study of Michelle Bachelet's 2006 ministerial appointments reveals initial evidence for the argument. Empirical implications are then tested with an original dataset of 1,908 ministers of all democratically elected Latin American presidents since 1999. Model results are consistent with the theory that presidentas are most likely to “make a difference” when they are least constrained by the supply of female ministerial candidates.  相似文献   
992.
993.
ABSTRACT

The Guatemalan National Revolutionary Unit (URNG) fought one of the longest and bloodiest civil wars in recent Latin American history. In 1996, the URNG and the Government of Guatemala signed a Firm and Lasting Agreement ending the country’s civil war and initiating the URNG’s post-war life as a political party. After finishing third in its initial electoral competition, the URNG has since been unable to capture more than 4% of the vote, on its own or in coalition, leaving it a minor political party. What explains the poor electoral performance of the URNG as a political party? Based upon fieldwork, elite interviews, and analysis of electoral data, I argue that the URNG’s minor party performance was caused by both organizational and institutional factors.  相似文献   
994.
Time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) is a well‐established surface technique that provides both elemental and molecular information from several monolayers of a sample surface while also allowing depth profiling or image mapping to be performed. Static TOF‐SIMS with improved performances has expanded the application of TOF‐SIMS to the study of a variety of organic, polymeric, biological, archaeological, and forensic materials. In forensic investigation, the use of a minimal sample for the analysis is preferable. Although the TOF‐SIMS technique is destructive, the probing beams have microsized diameters so that only small portion of the questioned sample is necessary for the analysis, leaving the rest available for other analyses. In this study, TOF‐SIMS and attenuated total reflectance Fourier transform infrared (ATR‐FTIR) were applied to the analysis of several different pen inks, red sealing inks, and printed patterns on paper. The overlapping areas of ballpoint pen writing, red seal stamping, and laser printing in a document were investigated to identify the sequence of recording. The sequence relations for various cases were determined from the TOF‐SIMS mapping image and the depth profile. TOF‐SIMS images were also used to investigate numbers or characters altered with two different red pens. TOF‐SIMS was successfully used to determine the sequence of intersecting lines and the forged numbers on the paper.  相似文献   
995.
Two cases of fatal intoxications with toluene due to glue sniffing are described. In case 1, the autopsy did not indicate cause of death, while in case 2, the cause of death was determined to possibly be due to mechanical asphyxia by drowning. As the decedents had a history of glue sniffing, toxicological analyses were performed. Using gas chromatography with flame ionization detector and gas chromatography/mass spectrometry (GC/MS) with headspace method, toluene was detected in biological samples. Toluene ranged from 3.81 to 20.97 μg/g, with the highest concentrations observed in liver and brain (13.82–20.97 μg/g) in both cases. Based upon this data, the cause of death in both cases was determined to be toluene poisoning. Toxicological investigations are extremely important and should be considered mandatory in all deaths thought to be due to volatile substance abuse, as well as all deaths that are thought to be due to poisoning in young people.  相似文献   
996.
This study highlights the problem of levamisole‐adulterated cocaine in context of active traffic participation. For the purposes of levamisole concentration monitoring in human serum, an analytical method based on LC‐MS/MS and solid‐phase extraction was applied. A Luna 5 μm C18 (2) 100 A, 150 mm × 2 mm column and a mobile phase consisting of A (H2O/methanol = 95/5, v/v) and B (H2O/methanol = 3/97, v/v), both with 10 mM ammonium acetate and with 0.1% acetic acid (pH = 3.2), were used. The validation experiments demonstrated that the method applied was appropriate for levamisole quantification in human serum. For 23% of levamisole‐positive samples, the concentrations exceeded 20 ng/mL. Therefore, the interaction of this drug with cocaine has to be considered as important for active traffic participation. As a consequence, monitoring of levamisole concentration in human serum is recommended, as long as it is used as cocaine adulterant.  相似文献   
997.
Given the general expectation that forest loss can alter biodiversity patterns, we hypothesize that blow fly species abundances differ in a gradient of native vegetation cover. This study was conducted in 17 fragments across different landscapes in central Brazil. Different land cover type proportions were used to represent landscape structure. In total, 2334 specimens of nine species of Calliphoridae were collected. We used principal component analysis (PCA) to reduce dimensionality and multicollinearity of the landscape data. The first component explained 70%, and it represented a gradient of forest‐pasture land uses. Alien species showed a wide distribution in different fragments with no clear relationship between the abundance values and the scores of PCA axes, whereas native species occurred only in areas with a predominance of forest cover. Our study revealed that certain native species may be sensitive to forest loss at the landscape scale, and they represent a bioindicator in forensic entomology.  相似文献   
998.
The aim of this study was to develop chemical improvements to the original Weber protocol, in order to increase the intensity and time length of light emission and to eliminate false‐positive reactions. The intensity and duration of light were measured on serial blood dilutions using a plate reader chemiluminometer. Blood stains of various concentrations were impregnated in pure cellulose, dried, and luminol solution was added with/without the potential enhancers. An in silico study was also conducted, aiming to demonstrate the enhancing mechanism of hemoglobin denaturation using 8 M urea. The luminol blood detection test revealed important improvements after urea pretreatment or in the presence of monochloro‐triazinyl‐β‐cyclodextrin. This approach also eliminated the false‐positive reaction from sodium hypochlorite. These improvements could provide a higher sensitivity under particular circumstances such as old or washed blood stains, leading to a better localization for further DNA typing and higher quality photographic analysis.  相似文献   
999.
This study was designed to produce the first baseline measure of reliability in bloodstain pattern classification. A panel of experienced bloodstain pattern analysts examined over 400 spatter patterns on three rigid non‐absorbent surfaces. The patterns varied in spatter type and extent. A case summary accompanied each pattern that either contained neutral information, information to suggest the correct pattern (i.e., was positively biasing), or information to suggest an incorrect pattern (i.e., was negatively biasing). Across the variables under examination, 13% of classifications were erroneous. Generally speaking, where the pattern was more difficult to recognize (e.g., limited staining extent or a patterned substrate), analysts became more conservative in their judgment, opting to be inconclusive. Incorrect classifications increased as a function of the negatively biasing contextual information. The implications of the findings for practice are discussed.  相似文献   
1000.
The prevalence of cardiac implantable electronic devices (CIEDs), pacemakers and implantable cardioverter defibrillators (ICDs) is increasing. However, postmortem analysis of CIEDs is not performed routinely. Fourteen consecutive CIEDs were analyzed. The indication for and date of implantation, technical data, CIED reprogramming, heart rhythm disturbances, patient demographics and medical consultations were investigated. Death during the first year after implantation was seen in 54%, whereof 71% consulted a physician within 10 days before death. The time of death was attributed to a particular day in 29%. There was a relationship between CIEDs and cause/manner of death in 50%. Although limited by a small sample size, this study advocates the routine postmortem CIED analysis for forensic and clinical purposes in selected cases. Patients with CIEDs seem to show an increased risk of death during the first year after implantation. The analysis of CIEDs can be helpful in evaluating the time/cause/manner of death.  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