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   2267篇
  免费   522篇
各国政治   414篇
工人农民   112篇
世界政治   332篇
外交国际关系   118篇
法律   1016篇
中国政治   45篇
政治理论   717篇
综合类   35篇
  2021年   32篇
  2020年   38篇
  2019年   158篇
  2018年   105篇
  2017年   157篇
  2016年   177篇
  2015年   151篇
  2014年   136篇
  2013年   596篇
  2012年   108篇
  2011年   105篇
  2010年   124篇
  2009年   58篇
  2008年   95篇
  2007年   70篇
  2006年   71篇
  2005年   55篇
  2004年   45篇
  2003年   37篇
  2002年   54篇
  2001年   13篇
  2000年   25篇
  1999年   25篇
  1998年   23篇
  1997年   23篇
  1996年   21篇
  1995年   23篇
  1994年   23篇
  1993年   27篇
  1992年   22篇
  1991年   15篇
  1990年   16篇
  1989年   14篇
  1988年   15篇
  1987年   12篇
  1986年   15篇
  1985年   14篇
  1984年   13篇
  1983年   11篇
  1982年   7篇
  1981年   13篇
  1980年   9篇
  1979年   6篇
  1978年   10篇
  1977年   7篇
  1976年   3篇
  1974年   6篇
  1972年   3篇
  1970年   1篇
  1967年   1篇
排序方式: 共有2789条查询结果,搜索用时 15 毫秒
971.
The characteristic life stages of infesting blowflies (Calliphoridae) such as Chrysomya megacephala (Fabricius) are powerful evidence for estimating the death time of a corpse, but an established reference of developmental times for local blowfly species is required. We determined the developmental rates of C. megacephala from southwest China at seven constant temperatures (16–34°C). Isomegalen and isomorphen diagrams were constructed based on the larval length and time for each developmental event (first ecdysis, second ecdysis, wandering, pupariation, and eclosion), at each temperature. A thermal summation model was constructed by estimating the developmental threshold temperature D0 and the thermal summation constant K. The thermal summation model indicated that, for complete development from egg hatching to eclosion, D0 = 9.07 ± 0.54°C and K = 3991.07 ± 187.26 h °C. This reference can increase the accuracy of estimations of postmortem intervals in China by predicting the growth of C. megacephala.  相似文献   
972.
Notwithstanding the 19th century formal abolition of slavery as legal ownership of people, modern slavery and forced labour have not been consigned to the past. In fact, their existence is more widespread, and made more difficult to tackle due to the lack of formal, legal criteria. This article suggests that reference to historical institutions reveals seven ‘badges of slavery’ that are helpful in identifying occurrences of modern slavery and forced labour. These are: humiliation, ownership of people, exploitation of the vulnerable, lack of consent, terms and conditions of employment, limits on the power to end the employment relationship, and denial of rights outside the work relationship. These constitute modern slavery, and distinguish it from other instances of exploitative employment relations, however problematic. In addition, even where the label of modern slavery is misplaced, the identification of particular badges of slavery in contemporary employment relations may assist in highlighting their troubling facets.  相似文献   
973.
974.
This work compares epidemiological and sociological data on persons having committed suicide in 2002 and in 2012 through a retrospective study of every suicide case having led to an autopsy at the Institute for Forensic Medicine of Lyon in 2002 and in 2012. The study included sociodemographic data, medical data, and toxicological data. A total of 486 cases were included (242 cases in 2002 and 244 cases in 2012). People committing suicide were on average older in 2012 than in 2002 with a larger proportion of over 55. There was also an increase in the proportion of psychiatric antecedents (p < 0.001). Whatever the date of death by suicide, the most affected age range is the 45–54. The results highlight the necessity of bolstering the prevention plans, in particular for people over 45.  相似文献   
975.
The Valsalva maneuver is used in clinical medicine for the diagnosis and/or treatment of various cardiovascular conditions. It can also be used in activities of daily living, such as defecation. Due to the cardiovascular effects produced during the Valsalva maneuver, it may be contraindicated in certain medical conditions and could be a trigger of sudden cardiac death. The incidence and prevalence of death following Valsalva maneuver in the presence of underlying cardiovascular disease, or “commode cardia,” has not been examined. In 2012, the Wayne County Medical Examiner's Office (Detroit, MI) investigated 21 deaths that occurred on the toilet, fourteen of which were due to cardiovascular disease. In another 31 deaths in the bathroom due to cardiovascular disease, the possibility that the decedent defecated immediately prior to death could not be excluded. Hence, the incidence of commode cardia in this population ranges from 2.3 to 7.4% of all cardiovascular‐related deaths.  相似文献   
976.
Pulmonary edema is a common finding in fatal methamphetamine intoxication. However, the underlying mechanism remains poorly understood. This study investigated the molecular pathology of alveolar damage involving pulmonary edema in forensic autopsy cases. Seven candidate reference genes (RPL13A, YWHAZ, GUSB, SDHA, GAPDH, B2M, and ACTB) were evaluated in the lung by the geNorm module in qBaseplus software. RPL13A, YWHAZ, and GUSB were identified as the most stable reference genes. Using these validated reference genes, intrapulmonary mRNA expressions of matrix metalloproteinases (MMPs), intercellular adhesion molecule‐1 (ICAM‐1), claudin‐5 (CLDN‐5), and aquaporins (AQPs) were examined. Relative mRNA quantification using TaqMan real‐time PCR assay demonstrated higher expressions of all markers except for AQP‐5 in fatal METH intoxication cases. These findings suggested alveolar damage and compensatory response in fatal METH intoxication cases. Systematic analysis of gene expressions using real‐time qPCR is a useful tool in forensic death investigation.  相似文献   
977.
The authors are exploring degradation patterns of latent fingermarks over time which can be quantitatively determined in a predictable manner by visual means. Several physical degradation parameters for assessing this hypothesis are evaluated. This article analyzes the parameter “minutiae count” as a function of time. Experiment variables included were secretion type (sebaceous‐rich and eccrine‐rich), substrate (glass and plastic), and exposure to light (dark, shade, and direct light). Depositions were sequentially visualized with Titanium Dioxide powder over a period of 6 months, photographed, and number of minutiae recorded. Results revealed a significant decrease of minutiae for eccrine‐rich marks on glass but insignificant for sebaceous‐rich marks on the same surface. However, significant degradation was observed for both types of secretions on plastic. The authors conclude that the distinctive prevalence of minutiae changes over time indicates with a high degree of certainty the hypothesis is valid and deserves additional exploration.  相似文献   
978.
The aim of this study was to automatically classify epiphyses in the distal radius and ulna using a support vector machine (SVM) and to examine the accuracy of the epiphyseal growth grades generated by the support vector machine. X‐ray images of distal radii and ulnae were collected from 140 Chinese teenagers aged between 11.0 and 19.0 years. Epiphyseal growth of the two elements was classified into five grades. Features of each element were extracted using a histogram of oriented gradient (HOG), and models were established using support vector classification (SVC). The prediction results and the validity of the models were evaluated with a cross‐validation test and independent test for accuracy (PA). Our findings suggest that this new technique for epiphyseal classification was successful and that an automated technique using an SVM is reliable and feasible, with a relative high accuracy for the models.  相似文献   
979.
980.
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