全文获取类型
收费全文 | 11122篇 |
免费 | 604篇 |
专业分类
各国政治 | 451篇 |
工人农民 | 402篇 |
世界政治 | 918篇 |
外交国际关系 | 345篇 |
法律 | 7391篇 |
中国共产党 | 1篇 |
中国政治 | 57篇 |
政治理论 | 2117篇 |
综合类 | 44篇 |
出版年
2021年 | 68篇 |
2020年 | 205篇 |
2019年 | 256篇 |
2018年 | 262篇 |
2017年 | 329篇 |
2016年 | 329篇 |
2015年 | 267篇 |
2014年 | 285篇 |
2013年 | 1107篇 |
2012年 | 255篇 |
2011年 | 327篇 |
2010年 | 301篇 |
2009年 | 315篇 |
2008年 | 307篇 |
2007年 | 279篇 |
2006年 | 303篇 |
2005年 | 272篇 |
2004年 | 262篇 |
2003年 | 253篇 |
2002年 | 259篇 |
2001年 | 476篇 |
2000年 | 431篇 |
1999年 | 300篇 |
1998年 | 196篇 |
1997年 | 160篇 |
1996年 | 127篇 |
1995年 | 125篇 |
1994年 | 150篇 |
1993年 | 141篇 |
1992年 | 204篇 |
1991年 | 221篇 |
1990年 | 206篇 |
1989年 | 218篇 |
1988年 | 206篇 |
1987年 | 193篇 |
1986年 | 236篇 |
1985年 | 210篇 |
1984年 | 163篇 |
1983年 | 172篇 |
1982年 | 122篇 |
1981年 | 124篇 |
1980年 | 89篇 |
1979年 | 134篇 |
1978年 | 79篇 |
1977年 | 77篇 |
1976年 | 72篇 |
1974年 | 74篇 |
1973年 | 67篇 |
1972年 | 67篇 |
1970年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
M L Weaver B K Gan E Allen L D Baugh F Y Liao R H Liu J G Langner A S Walia L F Cook 《Forensic science international》1991,49(1):43-56
Results obtained from three commercial immunoassay kits, Abuscreen, TDx, and EMIT, commonly used for the initial test of urine cannabinoids (and metabolites) were correlated with the 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (9-THC-COOH) concentration as determined by GC/MS. Correlation coefficients obtained based on 26 (out of 1359 total sample population) highly relevant samples, are 0.601 and 0.438 for Abuscreen and TDx. Correlation coefficients obtained from a parallel study on a different set of 47 (out of 5070 total sample population) highly relevant specimens are 0.658 and 0.575 for Abuscreen and Emit. The immunoassay concentration levels, that correspond to the commonly used 15 ng/ml GC/MS cutoff value for 9-THC-COOH, as calculated from the regression equations are 82 ng/ml and 75 ng/ml for TDx and EMIT and 120 ng/ml and 72 ng/ml for Abuscreen manufactured at two different time periods. The difference of these calculated corresponding concentrations provides quantitative evidence of the reagent specificity differences. 相似文献
942.
Hazards of mattresses, beds and bedding in deaths of infants 总被引:2,自引:0,他引:2
E Gilbert-Barness L Hegstrand S Chandra J L Emery L A Barness R Franciosi R Huntington 《The American journal of forensic medicine and pathology》1991,12(1):27-32
Of 52 infants who had died suddenly and were referred to autopsy, nine had lain on adult water beds for the first time; five had died as a result of accidents; two had died on water beds; two were in beds with widely spaced slats; and one had died as a result of strangulation. Three deaths were due to overlying. Three other infants had been placed on sheepskin rugs for the first time and were found dead shortly thereafter. These infants ranged in age from 2 to 9 months, except for a severely mentally retarded nine-year-old with spastic paraplegia. We believe that a general warning should be issued concerning water beds and that soft bedding should not be used for infants. Infants should not be placed unattended or left to sleep on water beds; only beds recommended for infants should be used. Overlying of a young infant is most likely to occur on a water bed, or if the parent is obese or has consumed alcohol. 相似文献
943.
944.
S O Baik J M Uku M Sikirica 《The American journal of forensic medicine and pathology》1991,12(4):334-336
The external beveling caused by an entrance gunshot wound to the skull has not been completely explained, but the mechanism is probably a combination of several factors including the angle of shot, twisting force of a rotating bullet, blow-back effect, velocity, shape and size of the bullet, outspread of the kinetic energy from the bullet, and resistance of the skull. 相似文献
945.
946.
S F Swinton 《Journal of forensic sciences》1999,44(5):1089-1090
The discovery of hair and fiber evidence can be of critical importance in the investigation of crimes, particularly violent crimes. A procedure is described for the construction and assembly of a roller device that utilizes readily available components and single-sided adhesive tape. The advantages over previously described roller devices include decreases in both the potential for contamination and the time required for construction of the device, as well as the ability to disinfect all of the roller components. 相似文献
947.
James S. Larson 《政策研究评论》2000,17(4):99-110
This study evaluates the emerging field of medical outcomes research based on interviews at Harvard Medical School. Medical outcomes research at Harvard is multifaceted, but may be summarized as involving certain key components. The emphasis at Harvard is on “quality of care,” viewed as a combination of outcomes evaluation and process evaluation, delivery of the service and its result. In a time of shrinking budgets, outcomes and process research can be justified economically because of the relatively low cost of patient self‐reports and because of their usefulness. Physicians may be motivated to measure quality of care by emphasizing the positive effects of research on the process of care and outcomes. Medical outcomes research is a field that is undergoing change and is becoming increasingly oriented toward the practical needs of patients and physicians. 相似文献
948.
949.
950.