全文获取类型
收费全文 | 10246篇 |
免费 | 220篇 |
专业分类
各国政治 | 463篇 |
工人农民 | 279篇 |
世界政治 | 593篇 |
外交国际关系 | 366篇 |
法律 | 6859篇 |
中国共产党 | 1篇 |
中国政治 | 35篇 |
政治理论 | 1743篇 |
综合类 | 127篇 |
出版年
2020年 | 91篇 |
2019年 | 115篇 |
2018年 | 167篇 |
2017年 | 169篇 |
2016年 | 208篇 |
2015年 | 136篇 |
2014年 | 174篇 |
2013年 | 993篇 |
2012年 | 273篇 |
2011年 | 311篇 |
2010年 | 224篇 |
2009年 | 220篇 |
2008年 | 282篇 |
2007年 | 274篇 |
2006年 | 273篇 |
2005年 | 220篇 |
2004年 | 258篇 |
2003年 | 249篇 |
2002年 | 254篇 |
2001年 | 430篇 |
2000年 | 387篇 |
1999年 | 305篇 |
1998年 | 98篇 |
1997年 | 117篇 |
1996年 | 90篇 |
1995年 | 97篇 |
1994年 | 105篇 |
1993年 | 106篇 |
1992年 | 207篇 |
1991年 | 246篇 |
1990年 | 226篇 |
1989年 | 250篇 |
1988年 | 237篇 |
1987年 | 217篇 |
1986年 | 222篇 |
1985年 | 196篇 |
1984年 | 180篇 |
1983年 | 182篇 |
1982年 | 98篇 |
1981年 | 93篇 |
1979年 | 136篇 |
1978年 | 89篇 |
1977年 | 82篇 |
1976年 | 81篇 |
1975年 | 91篇 |
1974年 | 113篇 |
1973年 | 106篇 |
1972年 | 91篇 |
1971年 | 94篇 |
1970年 | 78篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
983.
984.
Franklin G Miller 《The Journal of law, medicine & ethics》2008,36(3):560-566
Observational research involving access to personally identifiable data in medical records has often been conducted without informed consent, owing to practical barriers to soliciting consent and concerns about selection bias. Nevertheless, medical records research without informed consent appears to conflict with basic ethical norms relating to clinical research and personal privacy. This article analyzes the scope of these norms and provides an ethical justification for research using personally identifiable medical information without consent. 相似文献
985.
986.
987.
988.
P.M. Vallone M.C. Kline D.L. Duewer A.E. Decker J.W. Redman J.C. Travis M.V. Smith J.M. Butler 《Forensic Science International: Genetics Supplement Series》2008,1(1):80-82
National Institute of Standards and Technology SRM 2372 human DNA quantitation standard has been produced to support the need for a human-specific DNA quantitation standard in forensic casework and calibration of new quantitative polymerase chain reaction (qPCR) assays. The conventional DNA concentration has been assigned with one of the U.S. National Reference UV/Visible Spectrophotometers, assuming an absorbance of 1.0 at 260 nm equals 50 ng/μL of double stranded DNA. In addition, an interlaboratory study has been conducted, to verify that the SRM 2372 materials perform well in currently used DNA quantitation assays by the forensic DNA community. Each unit of SRM 2372 consists of three well-characterized DNA extracts. Component A is a single-source human male material derived from blood. Component B is a multiple-source human female material derived from blood. Component C was purchased as a purified unsheared genomic human DNA (Sigma-Aldrich Co., St. Louis, MO) obtained as a lyophilized human genomic extract and has both male and female donors. SRM 2372 is intended to enable the comparison of DNA concentration measurements across time and place. Manufacturers can use SRM 2372 to validate the values assigned to their own reference materials. Individual forensic laboratories can use SRM 2372 to validate DNA quantitation methods and to verify the assigned concentration of in-house or commercial DNA calibration standards. 相似文献
989.
G Siniscalco Gigliano 《Journal of forensic sciences》1999,44(3):475-477
A method is described to identify an unknown sample of plant material of forensic interest as Cannabis sativa L. The method consists in comparing the sequence of the nuclear ribosomal DNA Internal Transcribed Spacer I (ITS1) of the unknown sample with a Cannabis sequence. Our preliminary results show that the ITS1 is an ideal molecule for the identification of a sample suspected to be marijuana. 相似文献
990.
Among the known causes of aircraft disasters, sabotage is perhaps the most terrifying and difficult to comprehend. Bombs have been exploded in at least 34 commercial aircraft, with the resultant loss of more than 300 lives. Motives for these acts include profit, the deaths of certain persons, and politics. On November 1, 1955, United Airlines Flight 629, bound to Denver-Portland, exploded and burned in flight near Longmont, Colorado, a few minutes after takeoff, with the loss of all 44 on board. Investigation revealed that the plane had been destroyed by the explosion of a bomb that had been placed in the rear luggage hold in Denver. Twelve days after the disaster, John Gilbert Graham, the son of one of the female passengers, was arrested and charged with murder. He reportedly admitted placing a time bomb on board the aircraft, apparently in order to collect $37,500.00 in life insurance that he had taken on his mother's life. Though he soon recanted, he was convicted of murder and was executed. The potential for additional such crimes remains. 相似文献