全文获取类型
收费全文 | 19092篇 |
免费 | 409篇 |
国内免费 | 18篇 |
专业分类
管理学 | 2521篇 |
民族学 | 133篇 |
人才学 | 10篇 |
人口学 | 1609篇 |
丛书文集 | 184篇 |
理论方法论 | 1953篇 |
综合类 | 745篇 |
社会学 | 9957篇 |
统计学 | 2407篇 |
出版年
2023年 | 107篇 |
2022年 | 86篇 |
2021年 | 147篇 |
2020年 | 302篇 |
2019年 | 405篇 |
2018年 | 508篇 |
2017年 | 661篇 |
2016年 | 517篇 |
2015年 | 391篇 |
2014年 | 459篇 |
2013年 | 2994篇 |
2012年 | 690篇 |
2011年 | 698篇 |
2010年 | 563篇 |
2009年 | 470篇 |
2008年 | 578篇 |
2007年 | 611篇 |
2006年 | 606篇 |
2005年 | 562篇 |
2004年 | 461篇 |
2003年 | 403篇 |
2002年 | 425篇 |
2001年 | 446篇 |
2000年 | 426篇 |
1999年 | 387篇 |
1998年 | 302篇 |
1997年 | 264篇 |
1996年 | 248篇 |
1995年 | 249篇 |
1994年 | 257篇 |
1993年 | 246篇 |
1992年 | 272篇 |
1991年 | 245篇 |
1990年 | 234篇 |
1989年 | 212篇 |
1988年 | 232篇 |
1987年 | 236篇 |
1986年 | 192篇 |
1985年 | 211篇 |
1984年 | 238篇 |
1983年 | 199篇 |
1982年 | 205篇 |
1981年 | 170篇 |
1980年 | 158篇 |
1979年 | 160篇 |
1978年 | 123篇 |
1977年 | 109篇 |
1976年 | 130篇 |
1975年 | 131篇 |
1974年 | 115篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
A training project in a northern Canadian community providedan opportunity to examine participatory planning approachesand the meaning of work in First Nations communities. Focusgroups conducted three years after the unsuccessful interventionof a community economic development (CED) project suggest thatcomplex factors such as lack of support from community leadersand rate of pay for workers determine whether CED is alwaysappropriate in northern, First Nations contexts. 相似文献
133.
Many thousands of people in developing country cities depend on recycling materials from waste for their livelihoods. With the focus of the Millennium Development Goals on poverty reduction, and of waste strategies on improving recycling rates, one of the major challenges in solid waste management in developing countries is how best to work with this informal sector to improve their livelihoods, working conditions and efficiency in recycling.The general characteristics of informal recycling are reviewed, highlighting both positive and negative aspects. Despite the health and social problems associated with informal recycling, it provides significant economic benefits that need to be retained. Experience shows that it can be highly counterproductive to establish new formal waste recycling systems without taking into account informal systems that already exist. The preferred option is to integrate the informal sector into waste management planning, building on their practices and experience, while working to improve efficiency and the living and working conditions of those involved. Issues associated with integrating informal recycling into the formal waste management sector are discussed. 相似文献
134.
135.
136.
137.
Using a 1993 sample (n=107) of persons who teach disability studies courses, a sample (n=27) of disability studies syllabi from the early 1980s, and an extensive bibliography the authors discuss the history and the present condition of disability studies courses in the US and Canada. They discuss the disability paradigm and the methodology used in disability studies courses. The variety and geographical spread of such courses are noted. An extensive comparison of syllabi from the 1980s and the 1990s, including the reading assignments, is carried out. 相似文献
138.
Formulae are provided that define the ‘bend points’, the beginning and end of the essentially linear dose–response region, for the four‐parameter logistic model. The formulae are expressed in both response and dose units. The derivation of the formulae is shown in order to illustrate the general nature of the methodology. Examples are given that describe how the formulae may be used while planning and conducting bioassays. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
139.
Lesa L. Aylward Robert C. Brunet Thomas B. Starr Gaétan Carrier Elizabeth Delzell Hong Cheng Colleen Beall 《Risk analysis》2005,25(4):945-956
Recent studies demonstrating a concentration dependence of elimination of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) suggest that previous estimates of exposure for occupationally exposed cohorts may have underestimated actual exposure, resulting in a potential overestimate of the carcinogenic potency of TCDD in humans based on the mortality data for these cohorts. Using a database on U.S. chemical manufacturing workers potentially exposed to TCDD compiled by the National Institute for Occupational Safety and Health (NIOSH), we evaluated the impact of using a concentration- and age-dependent elimination model (CADM) (Aylward et al., 2005) on estimates of serum lipid area under the curve (AUC) for the NIOSH cohort. These data were used previously by Steenland et al. (2001) in combination with a first-order elimination model with an 8.7-year half-life to estimate cumulative serum lipid concentration (equivalent to AUC) for these workers for use in cancer dose-response assessment. Serum lipid TCDD measurements taken in 1988 for a subset of the cohort were combined with the NIOSH job exposure matrix and work histories to estimate dose rates per unit of exposure score. We evaluated the effect of choices in regression model (regression on untransformed vs. ln-transformed data and inclusion of a nonzero regression intercept) as well as the impact of choices of elimination models and parameters on estimated AUCs for the cohort. Central estimates for dose rate parameters derived from the serum-sampled subcohort were applied with the elimination models to time-specific exposure scores for the entire cohort to generate AUC estimates for all cohort members. Use of the CADM resulted in improved model fits to the serum sampling data compared to the first-order models. Dose rates varied by a factor of 50 among different combinations of elimination model, parameter sets, and regression models. Use of a CADM results in increases of up to five-fold in AUC estimates for the more highly exposed members of the cohort compared to estimates obtained using the first-order model with 8.7-year half-life. This degree of variation in the AUC estimates for this cohort would affect substantially the cancer potency estimates derived from the mortality data from this cohort. Such variability and uncertainty in the reconstructed serum lipid AUC estimates for this cohort, depending on elimination model, parameter set, and regression model, have not been described previously and are critical components in evaluating the dose-response data from the occupationally exposed populations. 相似文献
140.
David Oakes 《Revue canadienne de statistique》2005,33(3):465-468
The author characterizes the copula associated with the bivariate survival model of Clayton (1978) as the only absolutely continuous copula that is preserved under bivariate truncation. 相似文献