全文获取类型
收费全文 | 30274篇 |
免费 | 668篇 |
国内免费 | 161篇 |
专业分类
管理学 | 3300篇 |
劳动科学 | 12篇 |
民族学 | 361篇 |
人口学 | 3259篇 |
丛书文集 | 1800篇 |
理论方法论 | 1747篇 |
综合类 | 8289篇 |
社会学 | 8643篇 |
统计学 | 3692篇 |
出版年
2023年 | 101篇 |
2022年 | 203篇 |
2021年 | 310篇 |
2020年 | 289篇 |
2019年 | 340篇 |
2018年 | 1951篇 |
2017年 | 2091篇 |
2016年 | 1454篇 |
2015年 | 532篇 |
2014年 | 750篇 |
2013年 | 2219篇 |
2012年 | 1252篇 |
2011年 | 2190篇 |
2010年 | 2094篇 |
2009年 | 1834篇 |
2008年 | 1916篇 |
2007年 | 2187篇 |
2006年 | 1134篇 |
2005年 | 1142篇 |
2004年 | 901篇 |
2003年 | 775篇 |
2002年 | 779篇 |
2001年 | 666篇 |
2000年 | 391篇 |
1999年 | 258篇 |
1998年 | 168篇 |
1997年 | 168篇 |
1996年 | 194篇 |
1995年 | 134篇 |
1994年 | 105篇 |
1993年 | 144篇 |
1992年 | 157篇 |
1991年 | 126篇 |
1990年 | 145篇 |
1989年 | 118篇 |
1988年 | 126篇 |
1987年 | 122篇 |
1986年 | 104篇 |
1985年 | 91篇 |
1984年 | 121篇 |
1983年 | 102篇 |
1982年 | 95篇 |
1980年 | 98篇 |
1979年 | 106篇 |
1978年 | 73篇 |
1977年 | 84篇 |
1976年 | 71篇 |
1975年 | 86篇 |
1974年 | 71篇 |
1972年 | 64篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
We examine the labor-cost savings associated with privatization by comparing earnings and employment trends of public and
private sector refuse workers. Findings suggest that high union earnings for workers in the public sector are a source of
labor-cost savings in the refuse industry. Evidence on job changers does not indicate that earnings for this group of workers
are a compensating differential. Metropolitan area employment findings suggest that municipalities are less likely to use
union refuse workers in the public sector when a relatively small percentage of area residents belong to a union.
The authors thank Jacqueline Agesa, Keith Bender, Maria Crawford, and Richard Perlman for valuable suggestions. Research assistance
from Eric Blackburn is greatly appreciated. 相似文献
72.
随着环境问题的日益严重,要求制造技术的发展必须与自然资源和环境相结合.由此提出了一个新的制造概念——绿色制造.本文对绿色制造的概念及其内容体系进行了论述,并就以web技术为支撑平台的绿色制造技术做了进一步地探讨. 相似文献
73.
Craig H. Mallinckrodt John G. Watkin Geert Molenberghs Raymond J. Carroll 《Pharmaceutical statistics》2004,3(3):161-169
Missing data, and the bias they can cause, are an almost ever‐present concern in clinical trials. The last observation carried forward (LOCF) approach has been frequently utilized to handle missing data in clinical trials, and is often specified in conjunction with analysis of variance (LOCF ANOVA) for the primary analysis. Considerable advances in statistical methodology, and in our ability to implement these methods, have been made in recent years. Likelihood‐based, mixed‐effects model approaches implemented under the missing at random (MAR) framework are now easy to implement, and are commonly used to analyse clinical trial data. Furthermore, such approaches are more robust to the biases from missing data, and provide better control of Type I and Type II errors than LOCF ANOVA. Empirical research and analytic proof have demonstrated that the behaviour of LOCF is uncertain, and in many situations it has not been conservative. Using LOCF as a composite measure of safety, tolerability and efficacy can lead to erroneous conclusions regarding the effectiveness of a drug. This approach also violates the fundamental basis of statistics as it involves testing an outcome that is not a physical parameter of the population, but rather a quantity that can be influenced by investigator behaviour, trial design, etc. Practice should shift away from using LOCF ANOVA as the primary analysis and focus on likelihood‐based, mixed‐effects model approaches developed under the MAR framework, with missing not at random methods used to assess robustness of the primary analysis. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
74.
75.
H. Haario M. Laine M. Lehtinen E. Saksman J. Tamminen 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2004,66(3):591-607
Summary. We discuss the inversion of the gas profiles (ozone, NO3 , NO2 , aerosols and neutral density) in the upper atmosphere from the spectral occultation measurements. The data are produced by the 'Global ozone monitoring of occultation of stars' instrument on board the Envisat satellite that was launched in March 2002. The instrument measures the attenuation of light spectra at various horizontal paths from about 100 km down to 10–20 km. The new feature is that these data allow the inversion of the gas concentration height profiles. A short introduction is given to the present operational data management procedure with examples of the first real data inversion. Several solution options for a more comprehensive statistical inversion are presented. A direct inversion leads to a non-linear model with hundreds of parameters to be estimated. The problem is solved with an adaptive single-step Markov chain Monte Carlo algorithm. Another approach is to divide the problem into several non-linear smaller dimensional problems, to run parallel adaptive Markov chain Monte Carlo chains for them and to solve the gas profiles in repetitive linear steps. The effect of grid size is discussed, and we present how the prior regularization takes the grid size into account in a way that effectively leads to a grid-independent inversion. 相似文献
76.
Many recent institutional reforms of the financial system have relied on the introduction of an explicit scheme of deposit insurance. This instrument aims at two main targets, contributing to systemic stability and protecting depositors. However, it may also affect the interest rate spread in the banking system, which can be viewed as an indicator of either inefficiency or market power in this financial segment. This paper provides an empirical investigation of the effect of deposit insurance and other institutional and economic variables on bank interest rates across countries. We find that deposit insurance increases the lending–deposit spread in banking. The main effect seems to arise not from the deposit side though, but from an increase in the lending rate. We interpret this result as evidence of the presence of moral hazard problems related to this instrument. We also find that higher quality of institutions is associated with lower spreads, thus contributing to eroding sources of market power in the banking sector. 相似文献
77.
78.
79.
80.