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   17884篇
  免费   1243篇
各国政治   748篇
工人农民   869篇
世界政治   1158篇
外交国际关系   547篇
法律   12573篇
中国共产党   2篇
中国政治   120篇
政治理论   3015篇
综合类   95篇
  2023年   213篇
  2021年   119篇
  2020年   435篇
  2019年   453篇
  2018年   579篇
  2017年   593篇
  2016年   666篇
  2015年   514篇
  2014年   537篇
  2013年   1860篇
  2012年   500篇
  2011年   518篇
  2010年   552篇
  2009年   573篇
  2008年   528篇
  2007年   516篇
  2006年   527篇
  2005年   446篇
  2004年   442篇
  2003年   360篇
  2002年   407篇
  2001年   675篇
  2000年   608篇
  1999年   488篇
  1998年   241篇
  1997年   176篇
  1996年   200篇
  1995年   195篇
  1994年   171篇
  1993年   178篇
  1992年   310篇
  1991年   317篇
  1990年   304篇
  1989年   279篇
  1988年   314篇
  1987年   265篇
  1986年   322篇
  1985年   320篇
  1984年   250篇
  1983年   228篇
  1982年   178篇
  1981年   155篇
  1980年   145篇
  1979年   221篇
  1978年   118篇
  1977年   92篇
  1975年   94篇
  1974年   124篇
  1973年   80篇
  1972年   79篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
The content of ethanol and acetaldehyde in the limbic cortex and reticular formation of the brain was measured by gas-liquid chromatography in lethal ethanol poisoning. The content of acetaldehyde was significantly increased in the gyrus cinguli of the brain. Lethal poisonings occurred during any stage of ethanol intoxication. The data characterizing individual ethanol tolerance were obtained, which can be used for differential diagnosis of ethanol poisoning in practical forensic medicine.  相似文献   
952.
The morphology of adrenals was studied in cases of death from total supercooling. The intensity and terms of response are different in different morphofunctional zones of the adrenal cortex. Presumably, the terms and intensity of responses of various portions of the adrenal cortex reflect the specific features of their function regulation.  相似文献   
953.
Conclusions of 41 repeated expert evaluations of craniocerebral injuries within the framework of criminal and civil cases investigation are analyzed. Some aspects of clinical and forensic medical diagnosis of lethal and nonlethal injuries to the head, evaluation of the quality of medical care, and qualification of the severity of harm to health are discussed. Causes of typical expert errors and approaches to their prevention are shown.  相似文献   
954.
955.
A sensitive analytical method was developed for quantitative analysis of delta(9)-tetrahydrocannabinol (delta(9)-THC), 11-nor-delta(9)-tetrahydrocannabinol-carboxylic acid (delta(9)-THC-COOH), cannabinol (CBN) and cannabidiol (CBD) in human hair. The identification of delta(9)-THC-COOH in hair would document Cannabis use more effectively than the detection of parent drug (delta(9)-THC) which might have come from environmental exposure. Ketamine was added to hair samples as internal standard for CBN and CBD. Ketoprofen was added to hair samples as internal standard for the other compounds. Samples were hydrolyzed with beta-glucuronidase/arylsulfatase for 2h at 40 degrees C. After cooling, samples were extracted with a liquid-liquid extraction procedure (with chloroform/isopropyl alcohol, after alkalinization, and n-hexane/ethyl acetate, after acidification), which was developed in our laboratory. The extracts were analysed before and after derivatization with pentafluoropropionic anhydride (PFPA) and pentafluoropropanol (PFPOH) using a Hewlett Packard gas chromatographer/mass spectrometer detector, in electron impact mode (GC/MS-EI). Derivatized delta(9)-THC-COOH was also analysed using a Hewlett Packard gas chromatographer/mass spectrometer detector, in negative ion chemical ionization mode (GC/MS-NCI) using methane as the reagent gas. Responses were linear ranging from 0.10 to 5.00 ng/mg hair for delta(9)-THC and CBN, 0.10-10.00 ng/mg hair for CBD, 0.01-5.00 ng/mg for delta(9)-THC-COOH (r(2)>0.99). The intra-assay precisions ranged from <0.01 to 12.40%. Extraction recoveries ranged from 80.9 to 104.0% for delta(9)-THC, 85.9-100.0% for delta(9)-THC-COOH, 76.7-95.8% for CBN and 71.0-94.0% for CBD. The analytical method was applied to 87 human hair samples, obtained from individuals who testified in court of having committed drug related crimes. Quantification of delta(9)-THC-COOH using GC/MS-NCI was found to be more convenient than GC/MS-EI. The latter may give rise to false negatives due to the detection limit.  相似文献   
956.
Prehistoric Polynesian skeletal remains are frequently being recovered in New Zealand due to the increasing pace of urbanisation. Since such material must often be reinterred quickly, it is important that the sex of individuals be determined from the remains in a relatively short time. For this purpose, discriminant function analysis was utilised for sex determination of prehistoric adult New Zealand Polynesian tali (24 males and 27 females). Five measurements were taken and subjected to Statistical Package for the Social Sciences (SPSS) discriminant function analysis. For the discriminant functions derived, accuracy of sex determination ranged from 85.1 to 93.3%. Reduction in error over random assignment by sex ranged from 70 to 87%.  相似文献   
957.
Allele frequencies for the three STR loci included in the GenePrint CTT multiplex system (HUMTH01, HUMTPOX, HUMCSF1PO) have been determined for the four major sub-populations of New Zealand.  相似文献   
958.
959.
Self-report questionnaires are frequently used in youth research, but doubt remains whether total anonymity affects the results. This study compared the responses of 704 mainly 16–17-year-old adolescents to self-report measures of various health indicators in 2 groups: anonymous and confidential collection. For most health indicators no significant differences were found. Perceived health, use of alcohol, and aggressive behavior (for boys) were reported significantly less frequently in the confidential group (small effect size). It appeared that pupils with high scores on social desirability do not respond differently at most health indicators in the 2 conditions. For most health characteristics, epidemiologically useful outcomes may be derived from confidential self-report measures, which are also valuable for detecting individual at-risk children. Similar studies in lower grades and other types of education should confirm the results.Youth Department, Municipal Health Service Rotterdam area. Main research interests are emotional and behavioral problems of adolescents, youth health care, monitoring.Youth Department, Municipal Health Service Rotterdam area. Main research interests are emotional and behavioral problems of adolescents, youth health care, monitoring.Research Department, Municipal Health Service Rotterdam area. Major research interests include emotional and behavioral problems of adolescents, suicidal behavior, youth health care, monitoring.  相似文献   
960.
This study examined the ability of future certainty—an individual's perception of future stability, operationalized as the likelihood of certain life outcomes–to explain variance in delinquency and school adjustment, while controlling for economic, neighborhood, and family factors, among a cross-sectional sample of 1422 male and 1562 female African American adolescents drawn from the National Longitudinal Study of Adolescent Health (Add Health). Three kinds of future certainty were examined: future life certainty (e.g., life expectancy), marriage certainty, and college certainty. In hierarchical multiple regression analyses, future certainty and family functioning were stronger predictors than economic and neighborhood variables: neighborhood disorganization and family socioeconomic status. Future life certainty and expectations of attending college were stronger predictors of delinquency among males than females. Marriage certainty was the weakest predictor of the three certainty variables.  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