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   5518篇
  免费   204篇
各国政治   298篇
工人农民   213篇
世界政治   413篇
外交国际关系   179篇
法律   3294篇
中国共产党   1篇
中国政治   29篇
政治理论   1252篇
综合类   43篇
  2020年   68篇
  2019年   86篇
  2018年   110篇
  2017年   128篇
  2016年   134篇
  2015年   112篇
  2014年   116篇
  2013年   613篇
  2012年   147篇
  2011年   137篇
  2010年   121篇
  2009年   127篇
  2008年   151篇
  2007年   156篇
  2006年   149篇
  2005年   138篇
  2004年   148篇
  2003年   146篇
  2002年   145篇
  2001年   201篇
  2000年   196篇
  1999年   150篇
  1998年   84篇
  1997年   67篇
  1996年   52篇
  1995年   64篇
  1994年   63篇
  1993年   60篇
  1992年   105篇
  1991年   100篇
  1990年   117篇
  1989年   91篇
  1988年   93篇
  1987年   90篇
  1986年   108篇
  1985年   123篇
  1984年   90篇
  1983年   84篇
  1982年   56篇
  1981年   49篇
  1980年   47篇
  1979年   52篇
  1978年   60篇
  1976年   41篇
  1975年   48篇
  1974年   62篇
  1973年   55篇
  1972年   44篇
  1970年   37篇
  1969年   41篇
排序方式: 共有5722条查询结果,搜索用时 31 毫秒
991.
992.
Successful mitochondrial DNA (mtDNA) forensic analysis depends on sufficient quantity and quality of mtDNA. A real-time quantitative PCR assay was developed to assess such characteristics in a DNA sample, which utilizes a duplex, synthetic DNA to ensure optimal quality assurance and quality control. The assay's 105-base pair target sequence facilitates amplification of degraded DNA and is minimally homologous to nonhuman mtDNA. The primers and probe hybridize to a region that has relatively few sequence polymorphisms. The assay can also identify the presence of PCR inhibitors and thus indicate the need for sample repurification. The results show that the assay provides information down to 10 copies and provides a dynamic range spanning seven orders of magnitude. Additional experiments demonstrated that as few as 300 mtDNA copies resulted in successful hypervariable region amplification, information that permits sample conservation and optimized downstream PCR testing. The assay described is rapid, reliable, and robust.  相似文献   
993.
A procedure has been developed to analyze the trace element concentrations in glass fragments using particle-induced X-ray emission (PIXE) spectrometry. This method involves using accelerated protons to excite inner-shell electronic transitions of target atoms and recording the resultant X-rays to characterize the trace element concentrations. The protocol was able to identify those glass fragments that originated from different sources based on their elemental analyses. The protocol includes specific approaches to calculating uncertainties and handling measurements below the level of detection. The results indicate that this approach has increased sensitivity for several elements with higher atomic number compared with X-ray fluorescence methods. While not as sensitive as laser-ablation or inductively coupled plasma mass spectrometry methods of dissolved samples, it is entirely nondestructive and entails a much simpler sample preparation process that may be used to presort glass fragments for more comprehensive elemental analysis. As such, the technique described may have a niche role in forensic glass analysis.  相似文献   
994.
The chemical composition of fingermarks could potentially be important for determining investigative leads, placing individuals at the time of a crime, and has applications as biomarkers of disease. Fingermark samples containing triacylglycerols (TAGs) and other components were analyzed using laser desorption/ionization (LDI) time-of-flight mass spectrometry (TOF MS). Only LDI appeared to be useful for this application while conventional matrix-assisted LDI-TOF MS was not. Tandem MS was used to identify/confirm selected TAGs. A limited gender comparison, based on a simple t-distribution and peaks intensities, indicated that two TAGs showed gender specificity at the 95% confidence level and two others at 97.5% confidence. Because gender-related TAGs differences were most often close to the standard deviation of the measurements, the majority of the TAGs showed no gender specificity. Thus, LDI-TOF MS is not a reliable indicator of gender based on fingermark analysis. Cosmetic ingredients present in some samples were identified.  相似文献   
995.
Gender determination is an important step in identification in forensic medicine. CT measurements of maxillary sinuses may be useful to support gender identification. This study was undertaken to study the accuracy and reliability of maxillary sinus dimensions measurement in gender classification through the use of reconstructed helical CT images. Eighty-eight patients (43 men and 45 women) with age range from 20 to 49 years were selected in this study. The width, length, and height of the maxillary sinuses in addition to the total distance across both sinuses were measured. Data were subjected to discriminant analysis for gender using multiple regression analysis. Maxillary sinus height was the best discriminant parameter that could be used to study sexual dimorphism with an overall accuracy of 71.6%. Using multivariate analysis, 74.4% of male sinuses and 73.3% of female sinuses were sexed correctly. The overall percentage for sexing maxillary sinuses correctly was 73.9%. It can be concluded that reconstructed CT image can provide valuable measurements for maxillary sinuses and could be used for sexing when other methods of sexing are not conclusive.  相似文献   
996.
Through a comparison of fingermark sweat corrosion of α phase brass in both the U.K. and Iraq, we show how samples from Iraq have improved fingermark corrosion over U.K. samples that require no additional enhancement prior to visualization. Over 50% of Iraqi samples produced fingermark corrosion with full ridge detail compared with 0% from the U.K. X-ray photoelectron spectroscopy analysis of the fingermark corrosion products showed that Iraqi samples exhibit more dezincification with the Zn:Cu ratio averaging 1:1.82 compared with 1:3.07 for U.K. samples. Auger spectroscopy showed the presence of both zinc oxide and copper (I) oxide. No copper (II) was observed on the surface of the corroded brass. Opportunities to exploit the optical properties of these thin film oxides to enhance the visualization of fingermark corrosion are considered, and the potential to use fingermark corrosion of metal as a means of visualizing fingerprints in war zones is discussed.  相似文献   
997.
Juristische Blätter - Ziel der vorliegenden Arbeit ist es, einen roten Faden durch die verschiedenen Problemkreise einer rechtswidrigen Kündigung eines besonders bestandgeschützten...  相似文献   
998.
999.
This study examines the association between the facets of psychopathy embedded in the Psychopathy Checklist: Youth Version (PCL:YV; Forth et al., Psychopathy Checklist: Youth Version, 2003), and changes in institutional behavior and post-treatment violent and general offending in a sample of juvenile delinquent males treated in the Mendota Juvenile Treatment Center (MJTC), an intensive treatment program. Affective, Interpersonal, Behavioral and Antisocial facet scale scores were calculated from items of the Psychopathy Checklist: Youth Version (PCL:YV; Forth et al., 2003). Data on daily institutional behavior were collected from treatment records. In order to analyze re-offense patterns, the number and type of new criminal charges were collected over a mean follow-up of 54 months (range = 24–79 months), after the youth was released from custody. The Interpersonal facet of the PCL:YV was significantly related to admission behavior problems, while other facet scores were not. Youth with elevated Interpersonal facet scores showed the greatest improvement in institutional behavior during treatment. Treatment was also associated with a significant decrease in general and violent offending for each facet. The Interpersonal facet of the PCL:YV was found to play a key role in institutional and community violence in this study. Treatment appeared to disrupt the link between institutional and community violence and psychopathy features in this population.  相似文献   
1000.
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