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   6172篇
  免费   217篇
各国政治   249篇
工人农民   268篇
世界政治   465篇
外交国际关系   317篇
法律   3764篇
中国共产党   1篇
中国政治   39篇
政治理论   1241篇
综合类   45篇
  2023年   54篇
  2022年   28篇
  2021年   41篇
  2020年   102篇
  2019年   137篇
  2018年   168篇
  2017年   169篇
  2016年   179篇
  2015年   120篇
  2014年   164篇
  2013年   637篇
  2012年   178篇
  2011年   195篇
  2010年   142篇
  2009年   183篇
  2008年   175篇
  2007年   168篇
  2006年   169篇
  2005年   131篇
  2004年   150篇
  2003年   146篇
  2002年   126篇
  2001年   239篇
  2000年   235篇
  1999年   165篇
  1998年   78篇
  1997年   77篇
  1996年   64篇
  1995年   75篇
  1994年   64篇
  1993年   66篇
  1992年   129篇
  1991年   115篇
  1990年   142篇
  1989年   131篇
  1988年   143篇
  1987年   134篇
  1986年   112篇
  1985年   111篇
  1984年   84篇
  1983年   73篇
  1982年   57篇
  1981年   51篇
  1980年   43篇
  1979年   53篇
  1978年   38篇
  1976年   32篇
  1975年   28篇
  1974年   40篇
  1973年   32篇
排序方式: 共有6389条查询结果,搜索用时 15 毫秒
921.
922.
Sentencing juvenile offenders to life in prison is the most severe criminal penalty available, yet we know little about the factors that produce jurisdictional differences in the use of such sanctions. Political explanations emphasize conservative values and the strength of more conservative political parties. Threat accounts suggest that this sentence will be more likely in jurisdictions with larger minority populations. After controlling for many explanations using count models, the results show that larger numbers of juvenile life sentences are handed out in more politically conservative states with a stronger Republican Party. Findings also show that racial politics is a factor in juvenile life sentences. Those jurisdictions that have the most blacks and have judicial elections sentence the most juveniles to life terms. By highlighting the explanatory power of public ideologies, these findings support political explanations for the harshest criminal punishment directed towards juveniles.  相似文献   
923.
Frequently, international environmental negotiations have been analyzed in two-agent (2 × 2) games. Yet, in order to involve additional strategies, (3 × 3) games gained attention recently. We employ such a (3 × 3) game setting in order to depict international negotiations on climate change and integrate both the prisoner’s dilemma and the chicken games in this setting. We analyze transitions of negotiation states and describe how ancillary benefits and first-mover advantages influence agents’ behavior in the negotiations, when three different strategies or levels of climate protection efforts are available. Finally, we also integrate strategies to mitigate and to adapt to climate change into the analysis in the (3 × 3) game setting.  相似文献   
924.
Prolapse rectum (PR) or protrusion of the rectum beyond the anus occurs frequently in populations at both extremes of age. In the pediatric population, in developed countries, the commonest cause for PR is thought to be cystic fibrosis (CF). Treatment options for CF include conservative management, surgical resection and fixation, suturing, and injection sclerotherapy (IS). The last is considered an attractive treatment option because it is minimally invasive. In this case report, the authors present the details about a 2-year-old female child, with PR and CF, who died after IS, using phenol as the sclerotherapeutic agent. Autopsy findings and toxicology tests performed to establish phenol toxicity are documented. The available literature is reviewed. This case report underscores the risks of using phenol for IS and emphasizes the point that the procedure is not innocuous and an adverse outcome including fatality is a possibility.  相似文献   
925.
Social learning theory is one of the most prominent general theories of crime. Yet recent research has called into question its applicability to all offenders. Specifically, the influence of antisocial peers has been found to exert a stronger effect among those individuals evincing higher levels of criminal propensity (deemed social amplification), whereas other components of the theory have either not been shown to interact with criminal propensity or not been tested. This study examines several social learning theory components to determine whether its influence is dependent on an individual's level of self-control. Results suggest little support for the social amplification hypothesis as the components of social learning theory were found to operate similarly across individuals regardless one's level of self-control. Implications for criminological theory are discussed.  相似文献   
926.
927.
We study in this paper the expanding behaviour of hollow point 9 mm Parabellum projectiles (Hornady XTP(?) and Speer Gold Dot(?)). We defined a deformation rate that takes into account both the diameter increase and the length reduction. We plotted the behaviour of this parameter versus impact velocity (we refer to this curve as the expanding law). This expanding law has been plotted for different gelatin weight ratios and different gelatin block lengths. We completed our experiments with a set of high speed movies in order to correlate the deceleration to the state of expansion and size of the temporary cavity. Our results pointed out that full expansion is reached shortly after the projectile fully penetrates the gelatin. This result shows that the key point to accurately simulate human body interaction with a hollow point projectile is to accurately simulate the interface (skin, skull, clothes thoracic walls). Simulating accurately organs is only an issue if a quantitative comparison between penetration depths is required, but not if we only focus on the state of expansion of the projectile. By varying the gelatin parameters, we discovered that the expanding law exhibits a velocity threshold below which no expansion occurs, followed by a rather linear curve. The parameters of that expanding law (velocity threshold and line slope) vary with the gelatin parameters, but our quantitative results demonstrate that these parameters are not extremely critical. Finally, our experiments demonstrate that the knowledge of the expansion law can be a useful tool to investigate a gunshot in a human body with a semi-jacketed projectile, giving an estimation of the impact velocity and thus the shooting distance.  相似文献   
928.
929.
The in vitro production of GHB was observed in freshly collected, untreated whole blood samples using glass BD-Vacutainers and polypropylene S-monovettes. GHB concentrations were determined daily over a period of one week and after 3, 6 and 9 weeks again. Furthermore, the GHB concentration in 40 untreated random whole blood samples stored at 4°C for a longer period of time (10 samples 12 month, 10 samples 24 month and 20 samples 36 month) was also determined. For comparison, the in vitro production of GHB in freshly collected and prepared serum samples was observed. GHB serum concentrations were determined three times over a period of one week and once again after six weeks. Sample preparation was performed by means of methanolic extraction following the precipitation of whole blood and serum samples. A methanolic standard calibration was done in a low range of 0.005-0.1 μg/mL (LOD: 0.004, LLOQ: 0.013). For quantification a spiked blood bank serum with a determined GHB concentration of 0.09 μg/mL was used. Corrected calibrations in the range of 0.09-5.09 μg/mL were used (LOD: 0.08 μg/mL, LLOQ: 0.30 μg/mL), recovery: 91.3% (high level: 4.09 μg/mL) 50.5% (low level: 0.19 μg/mL). RESULTS: Relevant elevation of GHB was observed in all whole blood samples stored in liquid form (4°C or room temperature). In two of the 40 whole blood samples stored over a longer period of time at 4°C, GHB concentrations in the range of 13 μg/mL were even determined. These findings constitute grounds for caution. Even a GHB cut-off level of 5 μg/mL cannot be considered as "absolutely positive" proof of a case of exogenous administration, at least in untreated liquid blood samples in long time storage. However, no significant elevations of GHB were otherwise observed in any of the serum samples independently of storage temperature nor in the whole blood samples that were frozen for storage. CONCLUSIONS: The results suggest that the cut-off for exogenous GHB of 5 μg/mL could be lowered significantly, with the consequence of winning valuable time for the potential victim, but only if serum is collected for GHB determination or if the whole blood sample is frozen immediately after collection and the procedure well documented.  相似文献   
930.
A collaborative study on Raman spectroscopy and microspectrophotometry (MSP) was carried out by members of the ENFSI (European Network of Forensic Science Institutes) European Fibres Group (EFG) on different dyed cotton fabrics. The detection limits of the two methods were tested on two cotton sets with a dye concentration ranging from 0.5 to 0.005% (w/w). This survey shows that it is possible to detect the presence of dye in fibres with concentrations below that detectable by the traditional methods of light microscopy and microspectrophotometry (MSP). The MSP detection limit for the dyes used in this study was found to be a concentration of 0.5% (w/w). At this concentration, the fibres appear colourless with light microscopy. Raman spectroscopy clearly shows a higher potential to detect concentrations of dyes as low as 0.05% for the yellow dye RY145 and 0.005% for the blue dye RB221. This detection limit was found to depend both on the chemical composition of the dye itself and on the analytical conditions, particularly the laser wavelength. Furthermore, analysis of binary mixtures of dyes showed that while the minor dye was detected at 1.5% (w/w) (30% of the total dye concentration) using microspectrophotometry, it was detected at a level as low as 0.05% (w/w) (10% of the total dye concentration) using Raman spectroscopy. This work also highlights the importance of a flexible Raman instrument equipped with several lasers at different wavelengths for the analysis of dyed fibres. The operator and the set up of the analytical conditions are also of prime importance in order to obtain high quality spectra. Changing the laser wavelength is important to detect different dyes in a mixture.  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