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   11257篇
  免费   294篇
各国政治   498篇
工人农民   501篇
世界政治   833篇
外交国际关系   465篇
法律   6970篇
中国政治   78篇
政治理论   2167篇
综合类   39篇
  2023年   68篇
  2022年   55篇
  2021年   82篇
  2020年   155篇
  2019年   211篇
  2018年   296篇
  2017年   275篇
  2016年   302篇
  2015年   191篇
  2014年   252篇
  2013年   1190篇
  2012年   347篇
  2011年   358篇
  2010年   247篇
  2009年   296篇
  2008年   315篇
  2007年   325篇
  2006年   290篇
  2005年   229篇
  2004年   273篇
  2003年   246篇
  2002年   213篇
  2001年   499篇
  2000年   471篇
  1999年   337篇
  1998年   145篇
  1997年   143篇
  1996年   113篇
  1995年   110篇
  1994年   107篇
  1993年   88篇
  1992年   227篇
  1991年   226篇
  1990年   245篇
  1989年   226篇
  1988年   228篇
  1987年   231篇
  1986年   189篇
  1985年   192篇
  1984年   170篇
  1983年   154篇
  1982年   112篇
  1981年   116篇
  1980年   73篇
  1979年   124篇
  1978年   80篇
  1975年   65篇
  1974年   87篇
  1973年   80篇
  1972年   60篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
No reliable data are available on cases of lethal child abuse (by active force) in the area of Federal Republic of Germany prior to reunification (the former West Germany). In a multicenter study we therefore examined the police and court records for such cases occurring in the period 1 January 1985 to 2 October 1990 in nearly the entire area of Federal Republic of Germany. RESULTS: The study center received information on 58 cases of lethal child abuse. Extrapolated to all institutes of legal medicine, this corresponds to 62 cases in all of West Germany in the period studied. An approximately equal number of unreported cases should be added to this figure. Including unreported cases, at least 20 cases of lethal child abuse occurred per year; thus only one in every two cases ever came to light. Almost two thirds of the victims were younger than one year old. At autopsy 59% exhibited signs of repeated abuse at autopsy. By far the most common cause of death was direct impact from a blunt object, usually to the head. Mostly, the male person to whom the victim relates most closely (father, stepfather, partner of the mother) has killed the child. Twenty-one of the 74 persons charged saw the charges against them dropped or were acquitted due to lack of evidence; 51 received sentences ranging from one year probation to life. In the remaining two cases the outcome of the trial was unknown. Signs of abuse were readily apparent at autopsy in almost all cases. The high number of unreported cases underscores the need to educate medical students and practicing physicians to be on the look-out for signs of abuse and argues for an increase in the rate of autopsy.  相似文献   
943.
Histomorphometry was used to determine structural bone changes in drug addicts. Iliac crest bone biopsies were obtained at autopsy from 28 subjects (21 male, 7 female, aged 18 to 45 years) who had a history of drug abuse and had died due to overdose of illicit drugs. For histomorphometry, undecalcified sections were investigated using the Merz grid. The following histomorphometric indices were measured and calculated: BV/TV, BS/BV, Tb.Th, Tb.N, Tb.Sp, OV/TV, OS/BS, Ob.S/BS, O.Th, ES/BS, Oc.S/BS, and N.Oc/T.A. In 28 controls (24 male, 4 female, aged 17 to 47 years) trabecular bone specimens were investigated in the same way. The parameters in drug addicts did not show any correlation to age, body weight, height or sex differences. Trabecular bone volume and trabecular thickness were slightly but not significantly increased (BV/TV: 23.37 +/- 5.77% (mean, SD), controls 22.23 +/- 5.08%, p = 0.434; Tb.Th: 172.67 +/- 36.83 mcm, controls 169.73 +/- 36.13 mcm, p = 0.764). Only the eroded surface was significantly different to the controls (ES/BS: 8.16 +/- 2.04%, controls 6.96 +/- 2.17%, p = 0.038). We conclude that the incidence of metabolic bone disease in drug addicts is low.  相似文献   
944.
Taphonomy of marine environments has been studied mostly from individual cases. The formation of adipocere, or "grave-wax," is an important indicator of the postmortem interval. In the present paper, the conditions and the timing of adipoceric formation are observed in a series of 15 cadavers recovered at different times, over a period of 433 days, from the same contained environment. Initial foci of adipocere on the subcutaneous tissue of the cadavers were detected as early as 38 days from the time of immersion in cold (10-12 degrees C) sea water. The discrepancies between our findings and previous reports on the correlation between time since death and decomposition stages in marine environments are discussed.  相似文献   
945.
This article describes the application of solid-phase microextraction (SPME) to the recovery of manufacturing by-products and impurities from an illicit drug seizure. The preparation chosen for examination using this technique contained 4-methoxyamphetamine, an hallucinogenic amphetamine that has been encountered frequently in South Australia. Compounds found in the PMA preparation included 4-methoxyphenol, 4-methoxybenzaldehyde, 4-methoxyphenyl-2-propanone, 4-methoxyphenyl-2-propanol, 4-methoxyphenyl-propene, and (tentatively) 4-methyl-5-(4'-methoxyphenyl) pyrimidine. The presence of these compounds suggests that the active drug was prepared from 4-methoxybenzaldehyde via 4-methoxyphenyl-2-propanone using a Leuckardt reductive amination. In this instance, SPME was found to be a simple, rapid, and non-destructive recovery technique that gave results complementary to those provided by conventional liquid-liquid extraction. There is an indication that SPME might find application in profiling of illicit drugs.  相似文献   
946.
Allele distributions for 13 tetrameric short tandem repeat (STR) loci, CSF1PO, FGA, TH01, TPOX, VWA, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, and D21S11, were determined in African American, United States Caucasian, Hispanic, Bahamian, Jamaican, and Trinidadian sample populations. There was little evidence for departures from Hardy-Weinberg expectations (HWE) in any of the populations. Based on the exact test, the loci that departed significantly from HWE are: D21S11 (p = 0.010, Bahamians); CSF1PO (p = 0.014, Trinidadians); TPOX (p = 0.011, Jamaicans and p = 0.035, U.S. Caucasians); and D16S539 (p = 0.043, Bahamians). After employing the Bonferroni correction for the number of loci analyzed (i.e., 13 loci per database), these observations are not likely to be significant. There is little evidence for association of alleles between the loci in these databases. The allelic frequency data are similar to other comparable data within the same major population group.  相似文献   
947.
This study demonstrates that the locus D1S80 is highly polymorphic in the Bahrainian population. There were 24 different D1S80 alleles and 51 distinct genotypes observed in 198 Bahrainians. There was one allele observed that was smaller than the 14 repeat allele. This data set meets the Hardy-Weinberg expectations (HWE) and could be a useful marker for parentage testing and forensic applications.  相似文献   
948.
Beer consumption is commonly an issue in a medico-legal setting, requiring estimates either of a likely blood alcohol concentration (BAC) for a given pattern of consumption or vice versa. Four hundred and four beers and malt beverages available for sale in the State of Washington were tested by gas chromatography for their alcohol content. Considerable variability in the alcoholic strength was found, even within the same class. Overall the range of concentrations was 2.92%v/v to 15.66%v/v. The mean alcohol concentration for ales was 5.51%v/v (SD 1.23%v/v), and for lagers, 5.32% (SD 1.43%v/v). Some specialty brews had characteristically higher or lower mean concentrations: ice beers 6.07%v/v, malt liquor 7.23%v/v, light beer 4.13%v/v, seasonal ales 6.30%v/v. Six brands of lager and four light beers account for the majority of all beer sales in the United States, and the mean alcohol concentration for these products was measured as 4.73%v/v and 4.10%v/v respectively. Few of the beers (17%) were labeled with respect to alcohol content, and in some cases, there was a significant disparity between the concentration listed on the label, and the measured alcohol concentration. Toxicologists need to exercise caution when performing Widmark type calculations, using all available information to select the most appropriate estimate for alcoholic strength of a beer or malt beverage.  相似文献   
949.
A validation study was conducted to demonstrate that deoxyribonucleic acid (DNA) could be successfully extracted from human nail material and analyzed using short tandem repeat (STR) profiling and/or mitochondrial DNA (mtDNA) sequencing. This study involved the development of a DNA extraction protocol that includes a cleaning procedure designed to remove external contaminants (e.g., biological, chemical). This protocol was used to test human nail material that had been soaked in whole blood from a second donor and coated with gold-palladium to simulate scanning electron microscopic analysis. The results showed no indication of a mixture and were consistent with that of the nail donor. Fresh human nail material usually yielded both STR profiles and mtDNA sequence information; however, aged human nail material (approximately eight years old) yielded only mtDNA sequence information. Upon completion of the validation study, the extraction protocol was used for the analysis of a torn fingernail fragment recovered from the scene of a violent homicide in 1983. A partial STR profile and mtDNA sequence information indicated that the fingernail fragment was excluded as originating from the suspect and was, in fact, consistent with originating from one of the victims.  相似文献   
950.
Histological analysis of the viscera in experimental poisoning with psilocybin-containing mushrooms showed nonspecific changes in all examined organs, presenting as expressed hemocirculatory disorders and intracellular dystrophy. Quantitative histochemical analysis showed appreciable shifts in the activities of enzymes involved in the cytoplasmic and mitochondrial redox processes and of specific enzymes involved in nerve tissue metabolism. This may reflect some features in the direct effects of narcotic alkaloids contained in psilocybin-producing mushrooms.  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