全文获取类型
收费全文 | 5732篇 |
免费 | 119篇 |
专业分类
各国政治 | 236篇 |
工人农民 | 225篇 |
世界政治 | 456篇 |
外交国际关系 | 207篇 |
法律 | 3585篇 |
中国政治 | 49篇 |
政治理论 | 1076篇 |
综合类 | 17篇 |
出版年
2021年 | 40篇 |
2020年 | 69篇 |
2019年 | 103篇 |
2018年 | 131篇 |
2017年 | 115篇 |
2016年 | 118篇 |
2015年 | 68篇 |
2014年 | 118篇 |
2013年 | 583篇 |
2012年 | 140篇 |
2011年 | 151篇 |
2010年 | 122篇 |
2009年 | 138篇 |
2008年 | 167篇 |
2007年 | 155篇 |
2006年 | 140篇 |
2005年 | 129篇 |
2004年 | 156篇 |
2003年 | 123篇 |
2002年 | 100篇 |
2001年 | 310篇 |
2000年 | 277篇 |
1999年 | 194篇 |
1998年 | 80篇 |
1997年 | 79篇 |
1996年 | 52篇 |
1995年 | 54篇 |
1994年 | 48篇 |
1993年 | 38篇 |
1992年 | 121篇 |
1991年 | 139篇 |
1990年 | 131篇 |
1989年 | 126篇 |
1988年 | 113篇 |
1987年 | 125篇 |
1986年 | 100篇 |
1985年 | 95篇 |
1984年 | 96篇 |
1983年 | 83篇 |
1982年 | 57篇 |
1981年 | 73篇 |
1980年 | 34篇 |
1979年 | 73篇 |
1978年 | 43篇 |
1975年 | 37篇 |
1974年 | 49篇 |
1973年 | 54篇 |
1972年 | 39篇 |
1971年 | 34篇 |
1970年 | 29篇 |
排序方式: 共有5851条查询结果,搜索用时 15 毫秒
251.
252.
The purpose of this study was to examine differences in empathy between offender and nonoffender youth. Seventy-six male and 33 female juvenile offenders between the ages of 12 and 18 years and 33 male and 33 female nonoffenders between the ages of 15 and 19 years comprised the samples for this study. Measures of empathy, altruism, and social support were administered to all participants and then the participants were analyzed for status group differences. Only 1 dimension of empathy, emotional tone, was found to be significantly different based on group status. Gender differences were found for both status groups for another dimension of empathy, personal distress. Among offender and nonoffender youth, females yielded higher scores in personal distress than did males. Emotional tone and family structure were found to be the most predictive variables of offender status. Findings were discussed based on previous research and implications for interventions were addressed.Evaluation and Special Programs 相似文献
253.
254.
255.
256.
257.
258.
259.
The purpose of the present investigation was to test the accuracy of a new scoring system in recording tooth wear for age estimation. The material consisted of dental stone casts of 383 volunteers who had sound premolars and molars with normal occlusion. The degree of occlusal wear for all premolar and molar teeth was scored with the new system. The high intra- and inter-examiner concordances showed that the new score system was very reliable. The degree of tooth wear showed a significant positive correlation with age in each and every examined tooth of both males and females. Tooth wear scores of males were higher than those of females. Calculating tables for age estimation were designed and the accuracy of age estimation was obtained with the General Linear Models procedures. Our system could provide estimation of an individual's age within +/-3 years in 42.4% of males and 49.4% of females, within +/-5 years in 61.8% of males and 63.3% of females. When the subjects were divided into two age groups and data were re-treated, the accuracy of age estimation was increased. Collectively, it was shown that our new system for scoring tooth wear is a reliable and accurate method for age estimation. 相似文献
260.
Chaturvedi AK 《Journal of forensic sciences》2000,45(2):422-428
Existing proficiency-testing (PT) programs do not address the complexity of postmortem forensic toxicology. These programs do not include decomposed samples and solid tissues. Therefore, the Federal Aviation Administration in July 1991 started such a needed PT program. This program is used to: (i) professionally develop and maintain technical currency on a voluntary, interlaboratory, and self-evaluation basis, and (ii) quantifiably assess methods in the absence and presence of interfering substances. There are currently about 30 laboratories in the program. Functioning under various governmental/non-governmental agencies and academic institutions, these laboratories represent a broad cross-section of the country. PT samples are distributed quarterly, and result summaries are sent to the participants, while maintaining their anonymity. Since the inception of the program, 28 PT samples encompassing whole blood, plasma, urine, kidney, or liver, with (or without) drugs, metabolites, and common chemicals (nicotine, caffeine, beta-phenylethylamine, etc.) have been analyzed by the participants. Analytical findings were generally consistent with the anticipated values, but they were dependent on the nature and conditions of the specimens and types of the added analytes. Some incidences of false positives of concern were noted, as well. This PT program is one of the few programs recommended by the American Board of Forensic Toxicology in which laboratories may participate for their accreditation by the Board. It is anticipated that this PT program will continue to play a critical part in supporting the quality assurance/quality control (QA/QC) component of forensic toxicology, thereby enhancing operational performance. 相似文献