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   12452篇
  免费   412篇
各国政治   755篇
工人农民   367篇
世界政治   1026篇
外交国际关系   691篇
法律   6823篇
中国共产党   1篇
中国政治   66篇
政治理论   2984篇
综合类   151篇
  2021年   71篇
  2020年   143篇
  2019年   192篇
  2018年   314篇
  2017年   324篇
  2016年   394篇
  2015年   247篇
  2014年   275篇
  2013年   1631篇
  2012年   365篇
  2011年   354篇
  2010年   294篇
  2009年   309篇
  2008年   380篇
  2007年   408篇
  2006年   390篇
  2005年   324篇
  2004年   339篇
  2003年   314篇
  2002年   315篇
  2001年   403篇
  2000年   370篇
  1999年   319篇
  1998年   161篇
  1997年   186篇
  1996年   145篇
  1995年   140篇
  1994年   159篇
  1993年   154篇
  1992年   221篇
  1991年   233篇
  1990年   215篇
  1989年   220篇
  1988年   208篇
  1987年   179篇
  1986年   211篇
  1985年   162篇
  1984年   163篇
  1983年   159篇
  1982年   103篇
  1981年   106篇
  1980年   76篇
  1979年   129篇
  1978年   83篇
  1977年   76篇
  1976年   69篇
  1975年   77篇
  1974年   110篇
  1973年   85篇
  1972年   73篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
881.
Korea recently introduced three major health care reforms: in financing (1999), pharmaceuticals (2000), and provider payment (2001). In these three reforms, new government policies merged more than 350 health insurance societies into a single payer, separated drug prescribing by physicians from dispensing by pharmacists, and attempted to introduce a new prospective payment system. This essay compares the three reforms in Korea and draws important lessons about the country's changing process and politics of health care policy. The change of government, the president's keen interest in health policy, and democratization in the public policy process toward a more pluralist context opened a policy window for reform. Civic groups played an active role in the policy process by shaping the proposals for reform-a major change from the previous policy process that was dominated by government bureaucrats. The three reforms also showed important differences in the role of interest groups. Strong support by the rural population and labor unions contributed to the financing reform. In the pharmaceutical reform, which was a big threat to physician income, the president and civic groups succeeded in quickly setting the reform agenda; the medical profession was unable to block the adoption of the reform but their strikes influenced the content of the reform during implementation. Physician strikes also helped block the implementation of the payment reform. Future reform efforts in Korea will need to consider the political management of vested interest groups and the design of strategies for both scope and sequencing of policy reforms.  相似文献   
882.
The rapid further development of computed tomography (CT) and magnetic resonance imaging (MRI) induced the idea to use these techniques for postmortem documentation of forensic findings. Until now, only a few institutes of forensic medicine have acquired experience in postmortem cross-sectional imaging. Protocols, image interpretation and visualization have to be adapted to the postmortem conditions. Especially, postmortem alterations, such as putrefaction and livores, different temperature of the corpse and the loss of the circulation are a challenge for the imaging process and interpretation. Advantages of postmortem imaging are the higher exposure and resolution available in CT when there is no concern for biologic effects of ionizing radiation, and the lack of cardiac motion artifacts during scanning. CT and MRI may become useful tools for postmortem documentation in forensic medicine. In Bern, 80 human corpses underwent postmortem imaging by CT and MRI prior to traditional autopsy until the month of August 2003. Here, we describe the imaging appearance of postmortem alterations--internal livores, putrefaction, postmortem clotting--and distinguish them from the forensic findings of the heart, such as calcification, endocarditis, myocardial infarction, myocardial scarring, injury and other morphological alterations.  相似文献   
883.
In a scent identification line-up, a trained dog matches the scent trace left by a perpetrator at the crime scene to the odour of a suspect in a line-up of different odours. The procedures are strictly defined and the results are routinely used by the police and as evidence in court in a number of European countries. This paper describes the effect of ageing of the odour trace collected at the crime scene on the performance of the dogs in recognising the perpetrator in a line-up. The results show that whilst the dogs perform faultlessly in matching odours collected on the same day, the results drop to a lower level and become more variable in the period studied (2 weeks to 6 months). However, the results do not show a systematic decrease in performance. A possible explanation is the development of a steady state in the glass jars containing the perpetrator odour trace after initial differential evaporation of components of the residue or break down of unsaturated components into saturated ones. Prevention of this initial change may prevent the drop in performance observed in this study, thus increasing the reliability of these scent identifications.  相似文献   
884.
A new retrieval system for a 3D facial image database was designed and its reliability was experimentally examined. This system has two steps, firstly to automatically adjust the orientation of all 3D facial images in a database to that of the 2D facial image of a target person, and then to identify the facial image of the target person from the adjusted 3D facial images in the database using a graph-matching method. From the experimental study [M. Yoshino, K. Imaizumi, T. Tanijiri, J.G. Clement, Automatic adjustment of facial orientation in 3D face image database, Jpn. J. Sci. Tech. Iden. 8 (2003) 41-47], it is concluded that the software developed for the first step will be applicable to the automatic adjustment of facial orientation in the 3D facial image database. In 28 out of 110 sets (25.5%), the 3D image of the target person was chosen as the best match (from a database of 132 3D facial images) according to the similarity of the facial image characteristics based on the graph matching. The 3D facial image of the target person was ranked in the top of 10 of the database in 75 out of 110 sets (68.2%). These results suggest that this system is inadequate for the identification level, but may be feasible for screening method in a small database. It will be necessary to further pursue the possibility of realization of a facial image retrieval system for a large database such as suspects' facial images in future.  相似文献   
885.
The mathematical concept previously introduced for the forensic interpretation of DNA mixtures using non-associated genetic markers has been adapted to the assessment of haplotypes. Such calculus is required, for example, when Y-chromosomal markers are used in forensics. In addition to outlining the general mathematical framework, we devise two approaches to its practical computational implementation, involving either the inclusion-exclusion principle of probability theory or a recursion in the number of unknown contributors invoked. The two approaches scale differently, depending upon the complexity of the case and the diversity of the markers used. The performance of Y-chromosomal microsatellites (Y-STRs) as a means of trace donor discrimination has been assessed by simulation, using the derived formulas. Based upon data from the Y-chromosomal Haplotype Reference Database (YHRD), the exclusion chance of a non-contributor is shown to vary between 95% in the case of two contributors, and 70% for five contributors. With only one additional contributor, half of all contributing suspects would yield a log-likelihood ratio in favour of donorship of 1.61 or higher, although the median drops to 0.66 with four additional contributors. It must be emphasised that these estimates of the discriminatory power of Y-STRs are likely to be conservative since the simulations involved only haplotypes known to occur in YHRD.  相似文献   
886.
A qualitative and quantitative analytical method was developed and validated for the determination of 49 licit and illicit drugs in oral fluid. Small oral fluid samples, volume 1mL, were collected from volunteers using a modified Omni-Sal device and the analytes were extracted from an oral fluid/buffer mixture using a single Bond Elut Certify solid phase extraction cartridge. Liquid chromatography-tandem mass spectrometry (LC-MS-MS) and gas chromatography-repetitive full scan mass spectrometry (GC-MS) were used in parallel to analyze the extracts for the targeted drugs. Extracts were analyzed by GC-MS in their underivatized form and as their pentafluoropropionyl derivatives. Deuterated internal standards were used for quantification of drugs of abuse by LC-MS-MS to minimize matrix effects. Methadone-d(9) and tumoxetine were used as the internal standards for quantification of non-derivatized and derivatized analytes respectively by GC-MS. Linearity was demonstrated over the range 5-200 ng/mL and limits of detection were less than 4 ng/mL for each drug analyzed. The method demonstrated acceptable recoveries for most of the analytes and good intra- and inter-day precision. Acquisition of data by repetitive full scan GC-MS allows the addition of further analytes to the target menu.  相似文献   
887.
Spontaneous pneumomediastinum commonly occurs in healthy young men or parturient women in whom an increased intra-alveolar pressure (Valsalva maneuver, asthma, cough, emesis) leads to the rupture of the marginal pulmonary alveoli. The air ascends along the bronchi to the mediastinum and the subcutaneous space of the neck, causing cervico-fascial subcutaneous emphysema in 70-90% of cases. Ninety-five forensic cases, including five cases of hanging, were examined using postmortem multi-slice computed tomography (MSCT) and magnetic resonance imaging (MRI) prior to autopsy until December 2003. This paper describes the findings of pneumomediastinum and cervical emphysema in three of five cases of hanging. The mechanism of its formation is discussed based on these results and a review of the literature. In conclusion, when putrefaction gas can be excluded the findings of pneumomediastinum and cervical soft tissue emphysema serve as evidence of vitality of a hanged person. Postmortem cross-sectional imaging is considered a useful visualization tool for emphysema, with a great potential for examination and documentation.  相似文献   
888.
Steamer accidents, through contact with the bucket wheel, are very seldom today. No publication of such a kind of fatal accident could be found in literature. We present the case of a fatal steamer accident, in which the findings of a blunt traumatization of a person by the ship was completely documented by post-mortem combined multi-slice computed tomography (MSCT) and magnetic resonance imaging (MRI) examinations. A rupture of the aorta was detected using both radiological methods without use of radiopaque material. Radiological examination revealed a comminuted fracture of the thorax vertebrae at the same level as the aortic rupture. Injuries of the soft tissues of the back, caused by the bucket wheel of the steamer, were also diagnosed. In addition to the signs of blunt force trauma the findings of drowning such as an over inflation of the lungs, fluid in the stomach and duodenum were revealed. Furthermore, algological analysis detected diatoms in the lung tissue and blood from the left heart. Therefore, the cause of death was considered being a combination of fatal hemorrhage, caused by the aortic rupture, and drowning. We conclude that virtual autopsy using combined post-mortem MSCT and MRI is a useful tool for documentation, visualisation and analysis of the findings of blunt force trauma and drowning with a large potential in forensic medicine.  相似文献   
889.
Prevention science has produced information about risk and protective factors that predict adolescent drug use and related problem behaviors. This paper investigates the Communities That Care Youth Survey that measures multiple risk and protective factors. Using a sample of 172,628 students who participated in surveys administered in seven states in 1998, analyses were conducted to test the factor structure of these risk and protective factors and to test the equivalence of the factor models across five racial/ethnic groups (African Americans, Asians or Pacific Islanders, Caucasians, Hispanic Americans, and Native Americans), four grade levels (6th, 8th, 10th, and 12th) and both gender groups. Results support the construct validity of the surveys risk and protective factor scales and indicate that the measures are equally reliable across males and females and five racial/ethnic groups. Implications of these findings for science-based prevention planning are discussed.  相似文献   
890.
The capacity of police departments to solve crimes and apprehend offenders is low for many types of crime, particularly crimes of profit. This article reviews a variety of studies of police apprehension and hypothesizes that an important determinant of the ability of the police to apprehend criminals is information. The complete absence of information for many types of crime places fairly clear upper bounds on the ability of the police to effect solutions.To discover whether these boundaries are high or low we analyzed data from the 1973 National Crime Panel about the types and amount of information potentially available to police through victim reports and patrol activities. The evidence suggests that if the police rely on information made readily available to them, they will never do much better than they are doing now. On the other hand, there appears to be more information available to bystanders and passing patrols than currently is being used, which suggests that surveillance strategies and improved police methods for eliciting, recording, and analyzing information supplied by victims and witnesses might increase the probability of solving crimes and making arrests. In light of this we review a few possibly helpful innovations suggested in the literature on police productivity and procedure.  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