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   17329篇
  免费   570篇
各国政治   980篇
工人农民   740篇
世界政治   1215篇
外交国际关系   647篇
法律   10370篇
中国共产党   5篇
中国政治   202篇
政治理论   3583篇
综合类   157篇
  2020年   222篇
  2019年   281篇
  2018年   398篇
  2017年   434篇
  2016年   430篇
  2015年   335篇
  2014年   352篇
  2013年   1979篇
  2012年   442篇
  2011年   530篇
  2010年   411篇
  2009年   443篇
  2008年   487篇
  2007年   446篇
  2006年   467篇
  2005年   411篇
  2004年   442篇
  2003年   434篇
  2002年   373篇
  2001年   601篇
  2000年   579篇
  1999年   462篇
  1998年   259篇
  1997年   224篇
  1996年   219篇
  1995年   192篇
  1994年   203篇
  1993年   210篇
  1992年   326篇
  1991年   325篇
  1990年   315篇
  1989年   305篇
  1988年   308篇
  1987年   319篇
  1986年   326篇
  1985年   302篇
  1984年   295篇
  1983年   305篇
  1982年   184篇
  1981年   161篇
  1980年   151篇
  1979年   199篇
  1978年   149篇
  1977年   132篇
  1976年   126篇
  1975年   116篇
  1974年   112篇
  1973年   118篇
  1972年   112篇
  1968年   96篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
This paper examined the development role of community banks in rural Nigeria by using the deposit mobilization capability and funding capacity in key sectors of the rural economy as yardsticks. By using a cluster sampling technique, it looks at the achievements of the community banking scheme initiative in terms of economic development. The scheme, established in 1991, has sustained itself and promoted rural development in the country. It is noted that communities have, for the first time, realized that they can advance their own economic fortunes. However, the scheme's performance as supporter of the agricultural sector has not been as well as expected, despite the fact that agriculture dominates Nigeria's rural economy. In view of this, non-banking activities are a welcome development since some of their approaches are proven to be knowledge enhancing and empowering for the rural population. Overall, community banks should attempt to strengthen non-banking approaches by collaborating more with self-help groups or nongovernmental organizations to be more empowering, results-oriented, and sustainable. Moreover, regulatory authorities should ensure that guidelines relate to credit application in terms of volume and sector allocation.  相似文献   
992.
After surgical treatment of an inguinal hernia, a 26-year-old male was discharged from hospital with a well healing surgical wound. Four weeks later he was admitted again with a major localized painful swelling of the soft tissues, whereas the clinical examination revealed no further local or systemic signs of inflammation. The immediate operation disclosed no abscess formation, but a large colliquation necrosis of the subcutaneous tissue with an outstanding petroleum-like odour. On toxicological examination of the necrotic tissue, a respective petroleum distillate was found. The patient was confronted with the suspicion of having injected the petroleum preparation himself to prolong the wound healing and finally admitted the self-mutilating behaviour. The pathophysiology, clinical history and morphological findings are discussed in comparison with case reports of chemically induced self-mutilation.  相似文献   
993.
994.
A method is presented for the numerical analysis of sex differences in size and shape of the proximal humeral outlines using elliptical Fourier functions (EFFs). A skeletal sample consisting of right and left humeri pairs of 69 individuals, 36 males and 33 females, was used. The proximal superior view in the plane of the proximo-distal axis of each humerus was photographed and then 54 boundary points were located on the two-dimensional outline tracings. These points were digitized and used to compute EFFs with 27 harmonics. From the EFFs, a set of expected points on the proximal humeral outline was generated using the centroid as an origin. Superimposition of the male and female outlines on this centroid provided a detailed picture of the relative sex differences in size and shape with respect to that center. The bounded area of the proximal humeral outline showed statistically significant sex differences. Additionally, statistical results of the amplitudes derived from the "area-standardized" EFFs and visual assessments of the mean outline plots indicated significant sex differences in shape of the proximal humeral outlines. Focusing on localized regional differences, the greater tubercle was located more postero-medially and the lesser tubercle was located more anteriorly in the males compared to the females. Sex determinations from the proximal humeri were also examined with discriminant functions based on the amplitudes, which represent shape characteristics of the outline, and the hounded area. Using a cross-validation method, predictions of the percentages of cases correctly classified with the discriminant functions were ranged from 92.8% to 95.7% for the right and left humeral data. These results suggest that differences in size and shape of the proximal humeral outlines may be better predictors of sex when compared with conventional measurements of the humerus.  相似文献   
995.
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   
996.
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   
997.
Allele and genotype frequencies for three recently described short tandem repeat loci D1S1656, D12S391, and D18S535 were determined in a population sample from Asturias (North Spain). The loci were amplified using a fluorescence based PCR method and were typed automatically. No deviation from Hardy-Weinberg expectations were observed. The three loci proved to be highly discriminating and the allele frequencies observed are similar to those of the other European populations that have been typed for these loci to date.  相似文献   
998.
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   
999.
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   
1000.
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