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   18852篇
  免费   1165篇
  国内免费   5篇
各国政治   716篇
工人农民   978篇
世界政治   1208篇
外交国际关系   728篇
法律   12164篇
中国共产党   21篇
中国政治   432篇
政治理论   3331篇
综合类   444篇
  2022年   119篇
  2021年   137篇
  2020年   274篇
  2019年   340篇
  2018年   406篇
  2017年   438篇
  2016年   437篇
  2015年   341篇
  2014年   346篇
  2013年   1677篇
  2012年   641篇
  2011年   575篇
  2010年   530篇
  2009年   614篇
  2008年   690篇
  2007年   667篇
  2006年   652篇
  2005年   574篇
  2004年   575篇
  2003年   640篇
  2002年   573篇
  2001年   774篇
  2000年   579篇
  1999年   568篇
  1998年   268篇
  1997年   193篇
  1996年   240篇
  1995年   200篇
  1994年   237篇
  1993年   223篇
  1992年   358篇
  1991年   397篇
  1990年   376篇
  1989年   326篇
  1988年   345篇
  1987年   294篇
  1986年   350篇
  1985年   300篇
  1984年   251篇
  1983年   232篇
  1982年   189篇
  1981年   205篇
  1980年   132篇
  1979年   176篇
  1978年   128篇
  1977年   109篇
  1975年   129篇
  1974年   142篇
  1973年   107篇
  1972年   105篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
941.
The ?Literacy comes second? model is an experimental approach that may hold greater promise for the future than the traditional literacy classes. The model works with groups that already exist within the community, such as religious groups, groups meeting for business, residents? groups (especially in urban areas), local government and political groups. The main characteristic of these groups is that, from the point of view of literacy, they are mixed groups consisting of men and women who have different levels of literacy skills. The group members share their skills and experiences; thus every member is valued. The justification for the approach comes from an adult learning theory, which states that adults learn best through doing things in their own lives for real. In general, the goal for this approach is that people will learn how to read and write and use literacy skills to achieve developmental tasks.  相似文献   
942.
An intoxication following administration of morphine, tramadol and atracurium in a suicide case is reported. The route of administration and the amount of the particular drug were known from the investigation of the death scene and the findings of the postmortem examination. Tramadol was present in the gastric contents as well as in blood, liver, kidney and brain samples, whereas the drug could not be detected in muscle. All body fluids and tissues investigated contained morphine as well as its 3- and 6-glucuronides with the exception of muscle tissue. The concentrations of morphine and its glucuronide metabolites were determined by LC/MS following solid phase extraction. Interestingly, the concentration of M6G in brain, liver and kidney were close to the concentration of M3G in the particular tissue. This phenomenon might be explained by a preferential hydrolysis of M3G or by a preferential formation of M6G postmortem. Measurement of morphine and M6G in femoral blood and cerebrospinal fluid may be a useful indicator in rapid deaths.  相似文献   
943.
Nind AN 《Alberta law review》2000,38(2):536-562
In this article, the author examines the campaign leading up to the passage of the Sexual Sterilization Act in Alberta in 1928. The author asserts that the passage of this Act was the result of the influence of a few elite individuals, particularly those involved with the United Farm Women of Alberta social reform movement, and may not have been reflective of widespread favourable public sentiment. While there were serious misgivings regarding the passage of the Sexual Sterilization Act, the legislation was ultimately successful because of the pressing problems of inadequate mental facilities and budgetary constraints. The author discusses the legislation's eventual repeal in 1972 due to public denunciation of eugenic measures, concerns about liability, and the threat posed to individual liberties. This article was the winner of the William Morrow Essay Contest in 1999.  相似文献   
944.
Recent criminal acts in the United Kingdom, United States and other countries have demonstrated the dangers to public safety from the criminal use of improvised explosives on a large scale. Four sets of trials were carried out over four years, partly in collaboration with the United States Federal Bureau of Investigation, involving the firing of large bombs, mostly fertilizer based. The principal objectives of the firings were to measure the physical effects of the explosions upon objects representative of those that would be found at a real bomb scene and to recover any chemical traces deposited on these objects. The results are intended for use as an aid in determining the approximate size and type of an explosive employed in a terrorist attack. This paper describes the background behind the trials, the procedures for preparation of witness materials and charges, and the collection and analysis of physical and chemical evidence.  相似文献   
945.
Existing proficiency-testing (PT) programs do not address the complexity of postmortem forensic toxicology. These programs do not include decomposed samples and solid tissues. Therefore, the Federal Aviation Administration in July 1991 started such a needed PT program. This program is used to: (i) professionally develop and maintain technical currency on a voluntary, interlaboratory, and self-evaluation basis, and (ii) quantifiably assess methods in the absence and presence of interfering substances. There are currently about 30 laboratories in the program. Functioning under various governmental/non-governmental agencies and academic institutions, these laboratories represent a broad cross-section of the country. PT samples are distributed quarterly, and result summaries are sent to the participants, while maintaining their anonymity. Since the inception of the program, 28 PT samples encompassing whole blood, plasma, urine, kidney, or liver, with (or without) drugs, metabolites, and common chemicals (nicotine, caffeine, beta-phenylethylamine, etc.) have been analyzed by the participants. Analytical findings were generally consistent with the anticipated values, but they were dependent on the nature and conditions of the specimens and types of the added analytes. Some incidences of false positives of concern were noted, as well. This PT program is one of the few programs recommended by the American Board of Forensic Toxicology in which laboratories may participate for their accreditation by the Board. It is anticipated that this PT program will continue to play a critical part in supporting the quality assurance/quality control (QA/QC) component of forensic toxicology, thereby enhancing operational performance.  相似文献   
946.
Population genetics of nine STR loci in two populations from Brazil   总被引:2,自引:0,他引:2  
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   
947.
Two cases of threatening letters with their accompanying envelopes were received to the Division of Forensic Identification unit of the Israel Police. The envelopes, including the stamps, and the letters were initially examined for latent fingerprints by the DFO reagent, known to cause degradation of DNA. Although no latent fingerprints could be visualized on any of the items, the biology laboratory using organic DNA extraction, was successful in defining genetic profiles from all the items employing six STR loci, even after treatment with DFO. In a controlled experiment, a known donor attached a stamp, by licking, to an envelope. This item was treated with DFO and then profiled using STR loci. The results showed that previous DFO treatment on the control stamp before DNA analysis had no negative effects on obtaining the DNA profile of the known donor using STR loci.  相似文献   
948.
Our laboratory was asked to help with the rehydration of mummified human fingertips that had been removed from a recently deceased, unidentified female. Using a solution that was found in the archeological literature, we were able to successfully rehydrate dermal tissues to the extent that fingerprints could be taken. We believe that this solution, which until now has not been described in the forensic literature, is effective, affordable, and relatively easy to produce and use.  相似文献   
949.
In recent years the forensic scientist has been afforded great advances in technology both in the detection of latent bloodstains and in acquiring reliable DNA typing results from very small pieces of physical evidence. Scientists are now able to detect minute quantities of latent bloodstains by utilizing the luminol reagent, oftentimes indicating that an attempt has been made to conceal any evidence of bloodshed. With the introduction of PCR based technology to the forensic arena, scientists are now routinely able to obtain DNA typing results from previously insufficient amounts of biological material, items as small as a single hair, saliva on a cigarette butt, or a bloodstain the size of a pin head. We present here a merging of these two advances coupled with a new collection medium for post luminol treated latent bloodstains. The forensic scientist is now able to routinely isolate and recover an adequate amount of DNA suitable for PCR typing at all of the Promega GenePrint PowerPlex 1.1 loci. In this study, several dilutions of latent bloodstains were prepared in an effort to simulate transferred bloodstains that are routinely encountered in a crime scene setting. The latent bloodstains were treated with luminol and subsequently collected using conventional cotton tipped swabs as well as a Puritan sponge tipped swab. PCR typing at the Promega GenePrint PowerPlex 1.1 loci was then attempted upon all dilutions of the latent bloodstains for both collection mediums. The results clearly indicate that it is now routinely possible to recover adequate amounts of DNA suitable for PCR typing upon post luminol treated bloodstains.  相似文献   
950.
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   
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