全文获取类型
收费全文 | 2603篇 |
免费 | 44篇 |
专业分类
各国政治 | 126篇 |
工人农民 | 62篇 |
世界政治 | 152篇 |
外交国际关系 | 66篇 |
法律 | 1917篇 |
中国政治 | 21篇 |
政治理论 | 286篇 |
综合类 | 17篇 |
出版年
2020年 | 30篇 |
2019年 | 22篇 |
2018年 | 22篇 |
2017年 | 33篇 |
2016年 | 40篇 |
2015年 | 23篇 |
2014年 | 38篇 |
2013年 | 187篇 |
2012年 | 60篇 |
2011年 | 68篇 |
2010年 | 36篇 |
2009年 | 35篇 |
2008年 | 56篇 |
2007年 | 71篇 |
2006年 | 71篇 |
2005年 | 74篇 |
2004年 | 72篇 |
2003年 | 70篇 |
2002年 | 70篇 |
2001年 | 156篇 |
2000年 | 123篇 |
1999年 | 76篇 |
1998年 | 26篇 |
1995年 | 18篇 |
1994年 | 22篇 |
1993年 | 21篇 |
1992年 | 63篇 |
1991年 | 69篇 |
1990年 | 61篇 |
1989年 | 84篇 |
1988年 | 83篇 |
1987年 | 72篇 |
1986年 | 76篇 |
1985年 | 65篇 |
1984年 | 35篇 |
1983年 | 41篇 |
1982年 | 19篇 |
1981年 | 30篇 |
1979年 | 28篇 |
1978年 | 21篇 |
1977年 | 27篇 |
1976年 | 19篇 |
1975年 | 31篇 |
1974年 | 30篇 |
1973年 | 31篇 |
1972年 | 32篇 |
1971年 | 24篇 |
1970年 | 20篇 |
1969年 | 24篇 |
1968年 | 20篇 |
排序方式: 共有2647条查询结果,搜索用时 15 毫秒
771.
Erica L. Romsos M.F.S. Julie L. French M.S. Mark Smith B.S. Vincent Figarelli B.S. Frederick Harran M.S. Glenn Vandegrift Lilliana I. Moreno Ph.D. Thomas F. Callaghan Ph.D. Joanie Brocato Ph.D. Janaki Vaidyanathan M.S. Juan C. Pedroso A.A. Andrea Amy B.S. Stephanie Stoiloff M.S. Victor H. Morillo P.S.M. Karina Czetyrko P.S.M. Elizabeth D. Johnson M.S. Jessica de Tagyos M.S.F.S. Ashley Murray B.S. Peter M. Vallone Ph.D. 《Journal of forensic sciences》2020,65(3):953-959
Three commercially available integrated rapid DNA instruments were tested as a part of a rapid DNA maturity assessment in July of 2018. The assessment was conducted with sets of blinded single-source reference samples provided to participants for testing on the individual rapid platforms within their laboratories. The data were returned to the National Institute of Standards and Technology (NIST) for review and analysis. Both FBI-defined automated review (Rapid DNA Analysis) and manual review (Modified Rapid DNA Analysis) of the datasets were conducted to assess the success of genotyping the 20 Combined DNA Index System (CODIS) core STR loci and full profiles generated by the instruments. Genotype results from the multiple platforms, participating laboratories, and STR typing chemistries were combined into a single analysis. The Rapid DNA Analysis resulted in a success rate of 80% for full profiles (85% for the 20 CODIS core loci) with automated analysis. Modified Rapid DNA Analysis resulted in a success rate of 90% for both the CODIS 20 core loci and full profiles (all attempted loci per chemistry). An analysis of the peak height ratios demonstrated that 95% of all heterozygous alleles were above 59% heterozygote balance. For base-pair sizing precision, the precision was below the standard 0.5 bp deviation for both the ANDE 6C System and the RapidHIT 200. 相似文献
772.
Garrett Oetelaar D.V.M. Hock Gan Heng D.A.C.V.R. D.E.C.V.D.I. Chee Kin Lim D.E.C.V.D.I. Abigail Cox D.A.C.V.P. Hsin-Yi Weng Ph.D. 《Journal of forensic sciences》2020,65(5):1524-1529
Intraosseous T1-weighted (T1W) and short-tau inversion recovery (STIR) magnetic resonance imaging (MRI) signal intensity changes—so-called bone marrow edema—may be able to differentiate antemortem and postmortem fractures in human forensic imaging. The primary objective of this study was to investigate this hypothesis using an animal model. Three juvenile Landrace pigs were anesthetized and underwent MRI of both tibiae and both radii using a 1.5 T magnet. T1W, T2-weighted (T2W), STIR, and T2* sequences were included. Antemortem fractures were induced in both tibiae and postmortem fractures in both radii, and MRI was repeated. Two board-certified radiologists blinded to fracture group jointly evaluated the images for intraosseous and soft tissue signal intensity changes. Sensitivity (Se) and specificity (Sp) in identifying antemortem fractures were calculated based on intraosseous, soft tissue, and combined intraosseous and soft tissue signal intensity changes. Intraosseous and soft tissue signal intensity changes, when present, were hyperintense in all sequences. Intraosseous hyperintensity in T1W and T2W sequences yielded Sp of 100% for antemortem fractures. Regardless of sequence, soft tissue hyperintensity was comparatively more sensitive than intraosseous hyperintensity. Sensitivity for each sequence could be maximized by assessment of soft tissue and intraosseous hyperintense signals together; for the T1W sequence, such assessment optimized diagnostic utility yielding a Se of 100% and Sp of 83%. In summary, MRI—particularly the T1W sequence—can differentiate antemortem and postmortem fractures and may be a useful adjunct to the forensic analyses of fractures. 相似文献
773.
Emmanouil I. Sakelliadis M.D. M.Sc. Ph.D. Konstantinos D. Katsos M.D. Ph.D. Evmorfili I. Zouzia M.D. Konstantinos Moraitis B.Sc. M.Sc. Ph.D. Chara A. Spiliopoulou Pharm.D. M.D. Ph.D. 《Journal of forensic sciences》2020,65(3):991-994
We present two cases of elevator-related deaths that occurred in two different elevators, and deaths were caused by a similar, but unusual, mechanism. An elevator is a platform or compartment housed in a shaft for raising and lowering people or things to different levels. Elevator-related deaths and injuries are rarely reported in the literature. In most of these cases, cause of death was attributed to falls. It seems that most of the elevator accidents may be attributed to factors related to device maintenance inadequacies or even to device malfunctioning. In our cases, both elevator cars were not equipped with full-length inner doors, thus allowing both accidents to occur. Since 2014, the European Union adopted a relative directive, which imposes the need to equip all elevators with such full-length doors. The enforcement of the above-mentioned EU Directive is crucial, in order to prevent similar accidents in the future. 相似文献
774.
Decentralization is argued to enhance citizen–government relationships and, thus, to lead to higher levels of citizen trust. General purpose policing encompasses various services that might be assigned to different levels of governments. The literature lacks generalizable studies of the effects of the structural arrangements of police systems on police performance. This study is a cross‐national exploration of the relationship between the varying degrees of police decentralization and police performance as measured by citizen trust in the police. It uses a measure of decentralization of police systems based on the tiers of government with some control over police. Results show that, in the 72 sample countries, the relationship between citizen trust in police and decentralized police systems is not statistically significant. However, when the countries are categorized by the Human Development Index, decentralized police systems tend to be positively related to citizen trust in the more developed countries but inversely in the less developed countries. 相似文献
775.
776.
Cocaine in Wayne County Medical Examiner's cases 总被引:1,自引:0,他引:1
We determined the incidence of detection of cocaine or its metabolites in Wayne County (Michigan) Medical Examiner's cases from 1984 to 1987. Over this four-year period there was a significant (P less than 0.01) increase each year in evidence of recent cocaine use in this population, reaching 38.3% of all tested cases in 1987. Much of this increase was accounted for by homicide victims, especially those in their third or fourth decade of life, of whom 58.6 and 56.3%, respectively, tested positive in 1987. There was a large increase in recent cocaine use in teenage homicide victims in 1987, having previously changed little from 1984 to 1986. In victims of drug abuse, recent cocaine use also increased significantly (p less than 0.01) each year, reaching 47.6% in 1987, generally in combination with heroin. Although deaths attributed solely to cocaine were not as common, they also increased significantly each year from 4 in 1984 to 25 in 1987. Compared with the general population, those who use cocaine in Wayne County are more likely than those who do not to die prematurely, often as a result of violence. 相似文献
777.
E I Deriugina N I Drize L N Lemeneva E Iu Sadovnikova G A Udalov I L Chertkov 《Sudebno-meditsinskaia ekspertiza》1990,33(1):35-37
In this article serologic characteristics of monoclonal antibodies with anti-N specificity is given. Antibodies are directed to homologous sequence of N-form of A glycophorine (group-specific N-antigen) and B glycophorine, expressed both on N- and on M-erythrocytes. Higher titre and avidity of monoclonal antibodies with anti-N specificity in relation to erythrocytes with N-phenotype make it possible to detect N-antigen in material subjected to expert evaluation. 相似文献
778.
Government supported industry-university research centers: Issues for successful technology transfer
Dr. Michael D. Devine Dr. Thomas E. James Jr. Mr. Timothy I. Adams 《The Journal of Technology Transfer》1987,12(1):27-37
In order to increase the use of federally supported research and development to increase U.S. industrial competitiveness, new partnerships are being developed among the research producers, users, and funders. This paper summarizes the evolution of federal technology transfer models with particular attention to university-industry cooperative research centers sponsored by the National Science Foundation. The advantages and potential problems associated with such centers are presented and the implications for technology and innovation are discussed. 相似文献
779.
Deliberate ingestion of a corrosive acid is an unusual manner of death. Sulfuric acid, often used in electrical industry, chemical laboratories, and agriculture, is fatal at a dosage of 3.5-7.0 ml. The mortality rate is quite high, with only 35% recovery rate. Poisoning by sulfuric acid resembles other mineral acids in that the esophagus is more commonly spared while coagulative necrosis of the stomach is often apparent. A case involving the ingestion of sulfuric acid by a patient with a history of chronic psychiatric illness is presented. The pathological, clinical, and toxicological aspects of this case are discussed. 相似文献
780.