全文获取类型
收费全文 | 22814篇 |
免费 | 944篇 |
专业分类
各国政治 | 1170篇 |
工人农民 | 888篇 |
世界政治 | 1607篇 |
外交国际关系 | 834篇 |
法律 | 14219篇 |
中国共产党 | 5篇 |
中国政治 | 222篇 |
政治理论 | 4626篇 |
综合类 | 187篇 |
出版年
2020年 | 342篇 |
2019年 | 407篇 |
2018年 | 540篇 |
2017年 | 600篇 |
2016年 | 595篇 |
2015年 | 488篇 |
2014年 | 490篇 |
2013年 | 2498篇 |
2012年 | 555篇 |
2011年 | 674篇 |
2010年 | 572篇 |
2009年 | 604篇 |
2008年 | 613篇 |
2007年 | 562篇 |
2006年 | 596篇 |
2005年 | 542篇 |
2004年 | 578篇 |
2003年 | 552篇 |
2002年 | 482篇 |
2001年 | 841篇 |
2000年 | 759篇 |
1999年 | 623篇 |
1998年 | 339篇 |
1997年 | 274篇 |
1996年 | 272篇 |
1995年 | 255篇 |
1994年 | 269篇 |
1993年 | 288篇 |
1992年 | 455篇 |
1991年 | 450篇 |
1990年 | 409篇 |
1989年 | 433篇 |
1988年 | 399篇 |
1987年 | 422篇 |
1986年 | 423篇 |
1985年 | 404篇 |
1984年 | 372篇 |
1983年 | 400篇 |
1982年 | 251篇 |
1981年 | 225篇 |
1980年 | 199篇 |
1979年 | 285篇 |
1978年 | 208篇 |
1977年 | 180篇 |
1976年 | 168篇 |
1975年 | 151篇 |
1974年 | 158篇 |
1973年 | 166篇 |
1972年 | 146篇 |
1968年 | 127篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
131.
Ethanol was determined by gas chromatography in a variety of tissues and body fluids secured at autopsy in 61 cases. The specimens tested included right and left heart blood, femoral blood, pericardial fluid, cerebrospinal fluid, vitreous humor, urine, stomach contents, and brain. Statistical analysis of the cases revealed no significant differences among the various blood sites tested. However, the variations in blood ethanol concentrations among the various sampling sites within each case were as follows: 40 cases showed differences of less than 25%; 16 cases revealed variability between 25% and 50%, 4 cases had differences exceeding 50%. In one case, satisfactory blood analyses could not be accomplished. The larger variances occurred especially in those instances in which stomach alcohol concentration was 0.50% or greater. In one case, the variability amongst the different blood sites exceeded 400% (femoral blood--0.043%, right atrium--0.070%, root of aorta--0.156%); the brain was 0.050%, and the stomach contents was 1.2%. For all 61 cases, variances in blood alcohol content among the different sampling sites in a single cadaver ranged from 1.8 to 428%. 相似文献
132.
Conclusion The Regulations appear to have reinforced the protection available to software producers under United Kingdom law. The provisions of the Software Directive and the Regulations are complex and not without significant inconsistencies which are likely to prove to be a source of litigation. The drafters of the Regulations chose, unlike many of its European partners, not to adopt the wording of the Software Directive but to write their own interpretation, adding an element of uncertainty to the law in this area, which is perhaps inevitable bearing in mind the linguistic problems of translating and interpreting any directive coupled with the ambiguity and omission of definitions of several key terms. More important, however, than any academic argument will be the practical impact of the new law and its effectiveness in achieving its aim. 相似文献
133.
134.
Deoxyribonucleic acid (DNA) typing of ribosomal ribonucleic acid (rRNA) genes was performed with a polymerase chain reaction (PCR) assay for species identification. A variable region of the 28S ribosomal RNA gene was amplified with primers complementary to flanking sequences phylogenetically well conserved. The products of twelve animal DNAs (human, Japanese monkey, dog, cattle, pig, cat, rabbit, mouse, rat, chicken, frog, and fish) were separated by polyacrylamide gel electrophoresis, each revealing a few bands ranging from 150 to 100 base pairs. The band patterns obtained from each DNA sample differed in number and size, which indicates the applicability of the method to species identification. Samples containing either as little as 1 pg of DNA or degraded DNA of 0.2 to 0.5 kb in length were able to give detectable bands. Postmortem human tissue DNAs were tested as an example. They showed a pattern identical to the human control one, which was distinct from those of the other animals examined. 相似文献
135.
136.
137.
A report of an international collaborative experiment to demonstrate the uniformity obtainable using DNA profiling techniques. 总被引:2,自引:0,他引:2
P Gill S Woodroffe W B?r B Brinkmann A Carracedo B Eriksen S Jones A D Kloosterman B Ludes B Mevag 《Forensic science international》1992,53(1):29-43
This paper describes a collaborative exercise intended to demonstrate whether uniformity of DNA profile results could be achieved between different European laboratories. It was shown that this goal can be obtained provided that a common protocol is followed (specifically the use of a common electrophoretic buffer as being the most important parameter). Generally, lower molecular weight loci (with lower molecular weight fragments) such as YNH24 perform better than higher molecular weight loci such as MS43a. The results of the exercise are discussed in relation to the objectives of the European DNA profiling group (EDNAP). 相似文献
138.
Threatening and otherwise inappropriate letters to members of the United States Congress 总被引:2,自引:0,他引:2
P E Dietz D B Matthews D A Martell T M Stewart D R Hrouda J Warren 《Journal of forensic sciences》1991,36(5):1445-1468
The authors examine the characteristics of threatening and otherwise inappropriate communications sent to members of the U.S. Congress by a sample of 86 subjects, 20 of whom threatened assassination. We quote excerpts from these letters and provide quantitative data on such variables as the volume, duration, form, and appearance of such communications; the enclosures; the subjects' perceived relationships to the recipients; the thematic content of the communications; and the messages and threats communicated. Comparisons between 43 subjects who pursued encounters with members of Congress and 43 who did not revealed 17 factors associated with such pursuit. In this population, threateners were significantly less likely to pursue an encounter than inappropriate letter writers who did not threaten, regardless of the type of threat or the harm threatened. Inappropriate letters to members of Congress are compared with those directed to Hollywood celebrities. Mentally disordered persons writing to public figures often mention and sometimes threaten public figures other than those to whom the letters are addressed, which raises important issues regarding notification of endangered third parties and the sharing of information among protective agencies. 相似文献
139.
N C Martin A A Pirie L V Ford C L Callaghan K McTurk D Lucy D G Scrimger 《Science & justice》2006,46(3):179-184
In the forensic science laboratory, the recovery of spermatozoa from vaginal swabs, or vaginal cells from penile swabs, can help determine if sexual intercourse may have taken place. There are several methods used to recover spermatozoa and cells from the swabs before visualisation on a microscope slide and most of these methods use water. Phosphate buffered saline (PBS) is a non-toxic solution used in many biological laboratories. Unlike water, PBS prevents cells rupturing or shrivelling up due to osmosis. This study demonstrates that PBS can be used for the extraction of spermatozoa and cells from swabs and that PBS does not affect subsequent DNA profiling. 相似文献
140.
Devra C. Moehler 《Studies in Comparative International Development (SCID)》2007,42(1-2):164-190
Can participatory programs in transitioning countries increase the involvement of citizens beyond the level expected from individual-level characteristics, such as demographic traits, socioeconomic resources, and civic orientations? To answer this question, I examine the causes of participation in the Ugandan constitution-making process. Statistical analysis of a random sample survey of 820 citizens demonstrates that although individual-level factors play a role, many Ugandans participated because mobilizing agents pulled them into the process. I argue that programs to encourage active and equal participation will be most successful if they supplement weak indigenous institutions of mobilization and help all types of citizens to participate early on in the transition to democracy. 相似文献