全文获取类型
收费全文 | 17203篇 |
免费 | 463篇 |
专业分类
各国政治 | 711篇 |
工人农民 | 692篇 |
世界政治 | 1440篇 |
外交国际关系 | 586篇 |
法律 | 10308篇 |
中国共产党 | 2篇 |
中国政治 | 76篇 |
政治理论 | 3677篇 |
综合类 | 174篇 |
出版年
2020年 | 210篇 |
2019年 | 250篇 |
2018年 | 331篇 |
2017年 | 395篇 |
2016年 | 424篇 |
2015年 | 290篇 |
2014年 | 336篇 |
2013年 | 1681篇 |
2012年 | 406篇 |
2011年 | 432篇 |
2010年 | 342篇 |
2009年 | 388篇 |
2008年 | 448篇 |
2007年 | 468篇 |
2006年 | 449篇 |
2005年 | 391篇 |
2004年 | 399篇 |
2003年 | 418篇 |
2002年 | 377篇 |
2001年 | 684篇 |
2000年 | 618篇 |
1999年 | 509篇 |
1998年 | 284篇 |
1997年 | 244篇 |
1996年 | 207篇 |
1995年 | 206篇 |
1994年 | 247篇 |
1993年 | 219篇 |
1992年 | 337篇 |
1991年 | 370篇 |
1990年 | 326篇 |
1989年 | 344篇 |
1988年 | 317篇 |
1987年 | 332篇 |
1986年 | 338篇 |
1985年 | 331篇 |
1984年 | 287篇 |
1983年 | 317篇 |
1982年 | 256篇 |
1981年 | 239篇 |
1980年 | 179篇 |
1979年 | 249篇 |
1978年 | 168篇 |
1977年 | 144篇 |
1976年 | 131篇 |
1975年 | 121篇 |
1974年 | 136篇 |
1973年 | 118篇 |
1972年 | 112篇 |
1971年 | 94篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
912.
913.
Dolgin JL 《Brooklyn law review》2000,66(3):755-822
914.
The goal of the present study was to determine the relationship between substance use, drug selling, and lethal violence in adolescent male homicide offenders and their victims. The study employed a retrospective review of criminal justice databases and medical examiner records for murders committed by 25 adolescent males incarcerated in the Commonwealth of Virginia juvenile correctional centers from February 1992 to July 1996. The perpetrator sample was 84% African American and 16% white. The average age at the time of the offense was 15.0 years (range = 13.0 to 17.7 years). The victims were 84% male, 60% African American and 32% white. The median victim age was 28.0 years (mean = 34.8, range = 17 months to 75 years). The results indicated that 52% of the murders were committed by juveniles with identified involvement in drug selling, and 28% of the murders were drug-related. Toxicology results indicated recent drug or alcohol use in 27% of the victims; while 74% of the perpetrators reported substance use, 35% indicating daily use. Using discriminant analysis, it was possible to accurately classify 86% of the drug-related murders with the variables of recent victim drug use and perpetrator substance use history. The results indicated that adolescent males involved in the sale and distribution of illegal drugs comprised a significant percentage of those incarcerated for murder. Recent victim drug use and perpetrator substance use may be important variables in identifying drug-related juvenile homicides. These results underscore the link between substance use, drug selling, and lethal violence. 相似文献
915.
Corte-Real F Andrade L Anjos MJ Carvalho M Vieira DN Carracedo A Vide MC 《Journal of forensic sciences》2000,45(2):432-435
The Short Tandem Repeats (STRs) D3S1358, HUMvWA31/A, HUMFIBRA/FGA, D8S 1179, D2S11, D18S51, D5S818, D13S317, and D7S820 were studied in two Brazilian populations (from Amazonia and S. Paulo) using the "AmpF1 STR Profiler Plus PCR Amplification Kit." The nine loci showed a combined discrimination power greater than 0.9999999999 and a chance of exclusion of 0.9999. 相似文献
916.
Postmortem redistribution of morphine and its metabolites 总被引:2,自引:0,他引:2
The postmortem redistribution of morphine, morphine-3-glucuronide, morphine-6-glucuronide and total morphine was assessed in 40 heroin-related deaths. In blood taken from subclavian, heart, and femoral regions, concentrations of morphine and its metabolites were similar. While there was a trend for higher concentrations in heart blood, when compared with femoral or subclavian blood, this was not significant. There was also no significant difference in concentrations between admission and autopsy blood in which the postmortem interval was on average 59 h. From our observations, significant postmortem redistribution of morphine and its metabolites seems unlikely. 相似文献
917.
Lewis RJ Huffine EF Chaturvedi AK Canfield DV Mattson J 《Journal of forensic sciences》2000,45(4):898-901
During fatal aviation accident investigations, biosamples from the victims are submitted to the FAA Civil Aeromedical Institute (CAMI) for drug analysis. In the process of one such analysis by CAMI, an unknown substance was found in a urine sample. Simultaneous screening by thin layer chromatography (TLC) and gas chromatography/FID (GC/FID) suggested the presence of pseudoephedrine. A subsequent routine confirmation analysis of a separate urine aliquot by GC Fourier transform infrared (GC/FTIR) and GC mass spectrometry (GC/MS) indicated that the retention times of the unknown substance matched with those of pseudoephedrine. However, its infrared and mass spectra were different--the -OH and -NH groups were missing, a C-O-C group was present, and the molar mass was 12 atomic mass units (amu) more than that of pseudoephedrine. A subsequent literature search suggested that ephedrine-like amines react with aldehydes to form oxazolidines. Therefore, the 12-amu increase could be accounted for by condensation of pseudoephedrine with formaldehyde. Since this aldehyde is present in various grades of methanol and ethyl acetate, and these solvents were used during the solid-phase extraction, 3,4-dimethyl-5-phenyl-1,3-oxazolidine was synthesized by using (+)-pseudoephedrine HCl and formaldehyde. The analytical findings of the synthesized compound were consistent with those of the unknown interfering substance, confirming that it was the oxazolidine. Aldehyde contaminants in solvents or specimens can transform drugs of interest and may result in misidentification of a compound originally present in specimens. Therefore, chemicals used in analyses should be of the highest available purity, and a multi-analytical approach should be adopted to maintain a high degree of quality assurance. 相似文献
918.
Tahir MA Balraj E Luke L Gilbert T Hamby JE Amjad M 《Journal of forensic sciences》2000,45(4):902-907
A body was exhumed from the ground after 27 years. Samples of femur bone, tooth, and a fingernail were collected and successfully subjected to DNA extraction, quantitation, amplification, and subsequently typed for DQA1, polymarker, and nine STR loci. All three types of samples were typed for D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S17, D7S820, and amelogenin using ABI Prism 377 DNA sequencer. 相似文献
919.
A technique that exposes fingerprint residue to a gaseous electrical discharge in nitrogen followed by treatment with ammonium hydrogen carbonate vapors to produce fluorescence is investigated. Particular attention is made to fluorescence observed via laser illumination at 514 nm. Insight into the nature of the fluorescent components is achieved through the use of thin-layer chromatography (TLC) of fingerprint residue. Results reported indicate the fluorescence observed is from previously non-fluorescent fractions of the fingerprint residue, and TLC results point towards lipid derivatives as a possible source of the fluorescence. 相似文献
920.
During STR analysis on the 310 Genetic Analyzer, retarded migration of GS500ROX size standards and alleles in some samples was observed. The contribution of reagents, capillary and performance optimized polymer POP 4 to the observed anomaly was experimentally eliminated. Variation in electrophoresis temperature between 55 degrees C and 65 degrees C did not alter the rate of migration of GX500ROX size standard and sample alleles. An eroded connector for the cathode mounted on the heat plate assembly caused the abnormal migration. Hence, it is important to verify the mobility of all fragments in the size standard for each sample to avoid any erroneous allele calls by the automated data analysis software. 相似文献