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   3864篇
  免费   71篇
各国政治   106篇
工人农民   100篇
世界政治   168篇
外交国际关系   117篇
法律   2832篇
中国共产党   40篇
中国政治   63篇
政治理论   410篇
综合类   99篇
  2021年   21篇
  2020年   47篇
  2019年   45篇
  2018年   60篇
  2017年   49篇
  2016年   77篇
  2015年   40篇
  2014年   69篇
  2013年   288篇
  2012年   105篇
  2011年   157篇
  2010年   112篇
  2009年   84篇
  2008年   135篇
  2007年   152篇
  2006年   144篇
  2005年   106篇
  2004年   131篇
  2003年   128篇
  2002年   124篇
  2001年   167篇
  2000年   144篇
  1999年   109篇
  1998年   23篇
  1995年   19篇
  1993年   27篇
  1992年   62篇
  1991年   85篇
  1990年   85篇
  1989年   91篇
  1988年   95篇
  1987年   90篇
  1986年   75篇
  1985年   77篇
  1984年   67篇
  1983年   60篇
  1982年   24篇
  1981年   20篇
  1979年   30篇
  1978年   34篇
  1977年   22篇
  1976年   27篇
  1975年   28篇
  1974年   37篇
  1973年   37篇
  1972年   35篇
  1971年   36篇
  1970年   38篇
  1969年   33篇
  1968年   28篇
排序方式: 共有3935条查询结果,搜索用时 31 毫秒
991.
992.
Main and middle phalanx skin patterns represent a polymorphic hereditary system of signs practically not studied in anthropology, but interesting for forensic medicine and criminology from the viewpoint of expert evaluation of relation and personality identification. Based on a vast scope of data (600 hand impressions of 300 subjects from Russian families), a classification of patterns on the main and middle finger phalanges has been developed and their incidence evaluated. The proposed classification includes 15 types and 40 subtypes. The incidence of individual patterns on phalanges of different site and order has been determined. The problem of genetic determination, i.e. inheritance of certain patterns from father and mother, remains open and requires a special research.  相似文献   
993.
An improved method for computer-aided personality identification by the skull, based on the POSKID 1.1 software, consists in investigation of enlarged images of the skull and life-time photograph of the probable individual by coordinates of 49 anatomical points; independent quantitative evaluation of the aspect of each of the compared objects by the X, Y, and Z axes; formal evaluation of the results of comparative study of the skull-portrait by multidimensional discriminant analysis models. The proposed version differs from the POSKID 1.0 software in the method for evaluating the spatial position of the head on the portrait and adequate orientation of the skull in space, which necessitates the utilization of coordinate-regulated holder POSKID 1.1 method is based on multidimensional discriminant analysis and suggests a virtually reliable solution in 76.13-80.65% cases, a probable solution (positive and negative) in 11.61-18.06% cases, and motivated refusal from solution in 5.81-7.74% cases. In case of a probable or indefinite solution further investigations are recommended making use of life-time photographs with different aspects.  相似文献   
994.
The use of teeth as an important resource in the analysis of forensic case history by polymerase chain reaction (PCR) or other related methods has been reported. However, a major drawback in using teeth has been that the DNA is present only in trace amounts, and the methods to recover DNA from the flinty material have not been efficient or cost effective. In this report, we describe a method to prepare DNA from the hard tooth tissues. Our studies show that ultrasonication of teeth samples yields sufficient amounts of good quality DNA useful for PCR-based diagnostic methods. The teeth could serve as a reliable source of DNA for amplification-based forensic methods in sex determination. DNA could be obtained from any tooth, regardless of the age of subject. Furthermore, by using the AMEL gene-based primers in PCR, we have shown that the AMEL gene serves as a good marker for sex determination in the Indian population. In our study, the PCR-based method was sensitive and proved to be successful for sex determination with a complete specificity.  相似文献   
995.
996.
The authors describe an unusual case of suicide that required particular attention to establish whether the victim was murdered, was preparing a terrorist attack or had committed suicide. Examination of the corpse and the crime scene, as well as testimonies, led the authors to determine the real cause of death, namely, an unusual method of suicide.  相似文献   
997.
Benzo[f]ninhydrin was compared to ninhydrin for fingerprint development on paper. Overall, the performance of ninhydrin on exhibits was slightly better than that of benzo[f]ninhydrin. The significant advantages of the benzo[f]ninhydrin over ninhydrin were the much stronger fluorescence it gave after treatment with zinc salts and a slightly quicker reaction under ambient conditions. This fluorescence is, however, similar to that obtained with other reagents, such as DFO or ninhydrin analogs. These advantages apparently are not sufficient to justify regular usage of benzo[f]ninhydrin, especially when one considers its low solubility and high cost.  相似文献   
998.
In the years from 1982 to 1995, 20,504 autopsy cases were examined at the Departments of Forensic Medicine in Hamburg and Greifswald. In 103 cases death was caused by kicking. In the Greifswald area, the occurrence of kicking as the cause of death could be demonstrated in 68 cases (30% of all homicides), which is in contrast to the observations in Hamburg, were kicking amounted to only 2.5% of the homicides. Most of the victims (average age 44 years) were under the influence of alcohol (mean blood alcohol concentration 1.75/1000), and most were on social support. The victims often showed other signs of blunt trauma such as blows with the fist and strangulation. In a few cases, cutting and stabbing wounds were also found. In the majority of cases death was due to severe haemorrhages and aspiration of blood in addition to the direct effects of the head injuries. The crimes were committed by one person in 46 cases, two in 20 and three in 4 cases. The perpetrators (average age 27.6 years) were always younger than the victims. Case reports show that fatal kicking was mostly triggered by relatively trivial arguments. None of the incidents were preplanned by the perpetrators. In contrast to an expected higher incidence of kicking deaths in the urban area of Hamburg, these crimes occurred ten times more frequently in the rural area of Greifswald.  相似文献   
999.
Hair analysis by immunological methods from the beginning to 2000   总被引:2,自引:0,他引:2  
Immunoassays for hair testing must satisfy three requirements: (1) They must have cross-reactivity with parent drug and lipophilic metabolites actually found in hair (2) they must not experience interference from the dissolved hair matrix and (3) they must be titered for cutoffs appropriate to the drug concentrations found in hair. Because the analytes found in hair after drug use are generally the parent drug or its lipophilic metabolites, immunoassays developed and intended for urine testing are not suitable for hair. Immunoassays whose antibodies are bound to a solid support, such as coated-tube radioimmunoassay or coated-plate ELISA tests, experience less matrix interference than those which use other means of separation of bound and free fractions. Homogenous assays are not suitable for hair testing because the hair matrix frequently interferes in the detection of the signal. Historically radioimmunoassays for drugs of abuse were first used for detecting drugs in hair. Currently ELISAs and coated-plate 96 well microplate EIAs are employed for screening hair digests or extracts for drugs. The optimum cutoffs for immunoassays for drugs in hair should be chosen based on the analyte concentration which produces the fewest false positive or false negative results when applied to tests of hair from known users and non-users of drugs. A hair immunoassay test at these cutoffs should have a sensitivity and specificity of better than 90%. The predictive value of the test will depend on the prevalence of drug use in the tested population. Cutoffs or decision thresholds for immunoassays used for screening for drugs should not be at the limit of detection of the assay because that produces a very large incidence of false positives. Because immunoassays are ligand-binding assays, they have a short range of linearity with low precision at both ends of the range. In the future, immunoassays will continue to be used for screening hair and other matrices for drugs of abuse because they provide rapid, inexpensive automated procedures for separating negative specimens from those which are suspected of containing drugs. For forensic purposes, all positive results must be confirmed by an independent analysis using a procedure based on a different property of the analyte. An immunoassay test should not be confirmed by a second immunoassay test but by a chromatographic test performed on a different dissolved or extracted aliquot of the original specimen.  相似文献   
1000.
The aim of the present study was to establish an analytical method for the determination of clozapine in sweat and to determine whether the clozapine level in hair and sweat were correlated to the daily dose of clozapine delivered to patients. Twenty-six subjects treated with clozapine at 200-700 mg/day for refractory psychosis were included in the study. Clozapine was determined in plasma by liquid chromatography coupled to a diode array detection system, after extraction with an organic solvent at pH 9.5. Clozapine was extracted from hair and sweat patches specimens by incubation in methanol overnight at 40 degrees C. The residues were analyzed by gas chromatography coupled to mass spectrometry in the electronic impact mode of detection. It was possible to determine clozapine in concentrations ranging from 30 to 1016 ng/ml in plasma (n = 22), from 0.17 to 34.24 ng/mg in hair (n = 23) and from 49 to 5609 ng/patch in sweat (n = 20). Preliminary results suggest a lack of correlation between daily regimen of clozapine and plasma levels of the drug. Therefore, a better dose-concentration relationship was observed in our study between daily dose and hair concentration (r = 0.542, P < 7%) or between daily dose and sweat concentration (r = 0.589, P < 6%), but with wide variations for patients at the same posology. However, the idea of using quantitative drug measurements in hair or sweat to ascertain whether a patient has taken his treatment exactly as prescribed will remain inapplicable.  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