全文获取类型
收费全文 | 11902篇 |
免费 | 266篇 |
国内免费 | 1篇 |
专业分类
管理学 | 1473篇 |
民族学 | 54篇 |
人才学 | 3篇 |
人口学 | 1089篇 |
丛书文集 | 57篇 |
理论方法论 | 1026篇 |
综合类 | 103篇 |
社会学 | 5633篇 |
统计学 | 2731篇 |
出版年
2022年 | 63篇 |
2021年 | 64篇 |
2020年 | 174篇 |
2019年 | 218篇 |
2018年 | 324篇 |
2017年 | 433篇 |
2016年 | 278篇 |
2015年 | 235篇 |
2014年 | 288篇 |
2013年 | 2210篇 |
2012年 | 417篇 |
2011年 | 315篇 |
2010年 | 289篇 |
2009年 | 211篇 |
2008年 | 253篇 |
2007年 | 255篇 |
2006年 | 261篇 |
2005年 | 246篇 |
2004年 | 194篇 |
2003年 | 207篇 |
2002年 | 216篇 |
2001年 | 321篇 |
2000年 | 288篇 |
1999年 | 269篇 |
1998年 | 204篇 |
1997年 | 169篇 |
1996年 | 219篇 |
1995年 | 189篇 |
1994年 | 199篇 |
1993年 | 168篇 |
1992年 | 201篇 |
1991年 | 213篇 |
1990年 | 196篇 |
1989年 | 170篇 |
1988年 | 193篇 |
1987年 | 179篇 |
1986年 | 141篇 |
1985年 | 176篇 |
1984年 | 180篇 |
1983年 | 156篇 |
1982年 | 122篇 |
1981年 | 97篇 |
1980年 | 97篇 |
1979年 | 121篇 |
1978年 | 93篇 |
1977年 | 81篇 |
1976年 | 57篇 |
1975年 | 63篇 |
1974年 | 67篇 |
1973年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
691.
Paul S. Appelbaum 《Accountability in research》2013,20(2-4):265-276
Concern about the participation of incompetent subjects in psychiatric research has grown in the last several years. In response, the National Bioethics Advisory Commission (NBAC) recommended in its recent report that all investigations involving persons with mental disorders that may be associated with cognitive impairment that may pose greater than minimal risk to subjects utilize independent assessors to verify the capacities of subjects prior to entry into the study. This recommendation poses several problems for the conduct of research and the protection of research subjects. First, it fails to target that group of subjects most likely to be at risk for incapacity. Second, it focuses on too broad a range of research projects, many of which pose little risk to participants. The substantial costs of this approach are therefore not likely to be outweighed by concomitant benefits. In place of the NBAC recommendation, the author proposes a more flexible system of capacity assessment, designed to balance the costs with a greater likelihood of achieving meaningful protection for research subjects with mental disorders. 相似文献
692.
The usual formulation of subset selection due to Gupta (1956) requires a minimum guaranteed probability of a correct selection. The modified formulation of the present paper includes an additional requirement that the expected number of the nonbest populations be bounded above by a specified constant when the best and the next best populations are ‘sufficiently’ apart. A class of procedures is defined and the determination of the minimum sample size required is discussed. The specific problems discussed for normal populations include selection in terms of means and variances, and selection in terms of treatment effects in a two-way layout. 相似文献
693.
We consider the problem of UMVU estimation of a U-estimable function of four unknown truncation parameters based on two independent random samples from two two-truncation parameter families. In particular, we obtain the UMVU estimator of functional, P (Y > X). Also the confidence intervals for some parametric functions are obtained. 相似文献
694.
695.
696.
Certain recurrence relations for the moments of different orders of the largest order statistic from a gamma distribution with shape parameter p are obtained. By using this it is shown that for obtaining the moment of any order of each order statistic of a sample of size n from the gamma distribution, one has to evaluate at most n-2 single integrals. 相似文献
697.
Michael L. Hughes D.M.D. Donald W. Legler D.D.S. Ph.D. 《Journal of American college health : J of ACH》2013,61(6):293-296
Abstract The Student Dental Health Program (SDHP) is an open panel, prepaid dental insurance plan at the University of Alabama in Birmingham. The program was developed primarily to provide optimal dental health service; however the SDHP also serves educational and research functions that are consistent with the objectives of the university. The student bodies of the Schools of Dentistry, Medicine, Nursing, and Optometry constitute the enrollee population. Total cost rose from $18,418 in 1969–70 with 862 enrollees, to $70,930 in 1975–76 with 1,618 enrollees. During the same period the number of procedures completed increased from 2,868 to 6,796, with the average cost per procedure increasing from $6.42 to $10.44. The number of restorative services declined and preventive services increased. In 1976–77 benefits per student treated were estimated at $80 as compared to the annual fee of $48. The value of unmet needs upon entrance to the program averaged $59 per enrollee in 1974–75. By 1976–77 this figure was reduced to $26 due to implementation of an initial screening. The program is self-supporting due to a variety of cost containment measures. On balance, the program can be considered successful and beneficial to all parties concerned. 相似文献
698.
699.
700.
Lawrence S. Evans 《The American statistician》2013,67(2):79-81
Periodically, the pyramid or “chain letter” scheme is offered to Americans under the guise of a business dealership. Recently, the FTC ordered Glen Turner's “Dare to be Great” firm to repay 44 million dollars to participants. In order to demonstrate that the potential gains are misrepresented by promoters, a probability model of the pyramid scheme is developed. The major implications are that the vast majority of participants have less than a ten percent chance of recouping their initial investment when a small profit is achieved as soon as they recruit three people and that, on the average, half of the participants will recruit no one else and lose all their money. 相似文献