全文获取类型
收费全文 | 22704篇 |
免费 | 276篇 |
国内免费 | 1篇 |
专业分类
管理学 | 3052篇 |
民族学 | 144篇 |
人才学 | 3篇 |
人口学 | 3458篇 |
丛书文集 | 60篇 |
理论方法论 | 1569篇 |
综合类 | 396篇 |
社会学 | 10272篇 |
统计学 | 4027篇 |
出版年
2022年 | 67篇 |
2021年 | 67篇 |
2020年 | 181篇 |
2019年 | 230篇 |
2018年 | 1936篇 |
2017年 | 2035篇 |
2016年 | 1327篇 |
2015年 | 288篇 |
2014年 | 339篇 |
2013年 | 2355篇 |
2012年 | 745篇 |
2011年 | 1431篇 |
2010年 | 1311篇 |
2009年 | 990篇 |
2008年 | 1064篇 |
2007年 | 1240篇 |
2006年 | 287篇 |
2005年 | 493篇 |
2004年 | 470篇 |
2003年 | 425篇 |
2002年 | 315篇 |
2001年 | 348篇 |
2000年 | 316篇 |
1999年 | 291篇 |
1998年 | 218篇 |
1997年 | 183篇 |
1996年 | 261篇 |
1995年 | 197篇 |
1994年 | 211篇 |
1993年 | 176篇 |
1992年 | 211篇 |
1991年 | 230篇 |
1990年 | 212篇 |
1989年 | 180篇 |
1988年 | 213篇 |
1987年 | 184篇 |
1986年 | 147篇 |
1985年 | 183篇 |
1984年 | 195篇 |
1983年 | 167篇 |
1982年 | 133篇 |
1981年 | 109篇 |
1980年 | 104篇 |
1979年 | 127篇 |
1978年 | 101篇 |
1977年 | 83篇 |
1976年 | 61篇 |
1975年 | 67篇 |
1974年 | 69篇 |
1973年 | 65篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
In 1985, the National Institute on Drug Abuse (NIDA) funded an ethnographic research project in San Francisco to study the needle sharing behavior of injection drug users (IDUs). The goal of the research was to develop a strategy to slow the spread of HIV among this hidden and hard to reach population of drug users and their sexual partners. This small-scale project grew into a model intervention in which bleach, condoms, and street-based education by outreach workers were employed to inform IDUs of the risk of AIDS and of methods for protecting themselves. The "reach and teach bleach" model was adopted by NIDA and implemented in a number of American cities. This study describes the development of the model intervention, the adoption of the model by NIDA as part of its National AIDS Demonstration Research (NADR) project, and the political circumstances under which the city of San Francisco applied for the NADR grant. Drawing on Social Worlds/Arena theory, and based on extensive interviews and participant observation, a sociohistorical analysis examines the initial development, implementation, and disintegration of the model outreach project and the impact of the program on drug policy in the city of San Francisco. 相似文献
52.
This study examines the influence of the socialization of aggression among different gender and social class groupings and the influence of psychosocial stage on cognitive developmental play preferences among groups of school aged children. Observations of 143 play groups were coded for play preference (symbolic play, practice play, games with rules) and play performance (cooperative or competitive). Findings of the log-linear data analysis suggest a middle class and masculine bias in Piaget's cognitive model (i.e., that as age increases children prefer more games with rules). This model held only for middle class and affluent boys. Girls (both latency and prepubertal) and lower socioeconomic groups tended to prefer practice play. Girls were more likely to play cooperatively; boys more likely to play competitively. Implications for theory development and clinical practice are explored. 相似文献
53.
Douglas H. Sprenkle 《Journal of marital and family therapy》1992,18(3):221-222
54.
Research has repeatedly demonstrated that parent and child reports of child behavior and emotional functioning often do not agree in terms of symptom severity or even symptom presence. Given the potential clinical impact that discrepant reports may have on the therapeutic process, a significant amount of research has addressed the factors influencing this observed discrepancy. Traditionally, this research has evaluated the impact of demographic factors on mean differences and obtained correlation coefficients between parent and child reports. The current research improves upon previous research in this area in two ways. First, the current research uses parent and child measures with identical rather than similar items as is commonly found in previous research. Second, the current research moves beyond identifying demographic influences on discrepant reports by explaining observed discrepancies in terms of differences in parent and child perceptions of typical child behavior.David Carlston and Benjamin Ogles are affiliated with Department of Psychology, Ohio University, Athens, USA.Funding for this project was provided by the Ohio Department of Mental Health. 相似文献
55.
We employ vector autoregressive techniques to determine the current state of the labor queue. Unemployment rate differentials
have narrowed in recent years, potentially due to a change in the queue ordering, though a tight labor market and a stable
queue would yield similar results. We find no evidence that the queue ordering has changed, which brings into question the
resiliency of gains made by minority groups. We employ the same techniques to reveal the state of the queue across geographic
regions and find that substantial differences exist across regions, implying variation in the relative labor force status
of demographic groups. 相似文献
56.
Stuart G. Baker Barnett S. Kramer 《Journal of the Royal Statistical Society. Series C, Applied statistics》2005,54(5):941-954
Summary. When evaluating potential interventions for cancer prevention, it is necessary to compare benefits and harms. With new study designs, new statistical approaches may be needed to facilitate this comparison. A case in point arose in a proposed genetic substudy of a randomized trial of tamoxifen versus placebo in asymptomatic women who were at high risk for breast cancer. Although the randomized trial showed that tamoxifen substantially reduced the risk of breast cancer, the harms from tamoxifen were serious and some were life threaten-ing. In hopes of finding a subset of women with inherited risk genes who derive greater bene-fits from tamoxifen, we proposed a nested case–control study to test some trial subjects for various genes and new statistical methods to extrapolate benefits and harms to the general population. An important design question is whether or not the study should target common low penetrance genes. Our calculations show that useful results are only likely with rare high penetrance genes. 相似文献
57.
Point processes are the stochastic models most suitable for describing physical phenomena that appear at irregularly spaced
times, such as the earthquakes. These processes are uniquely characterized by their conditional intensity, that is, by the
probability that an event will occur in the infinitesimal interval (t, t+Δt), given the history of the process up tot. The seismic phenomenon displays different behaviours on different time and size scales; in particular, the occurrence of
destructive shocks over some centuries in a seismogenic region may be explained by the elastic rebound theory. This theory
has inspired the so-called stress release models: their conditional intensity translates the idea that an earthquake produces
a sudden decrease in the amount of strain accumulated gradually over time along a fault, and the subsequent event occurs when
the stress exceeds the strength of the medium. This study has a double objective: the formulation of these models in the Bayesian
framework, and the assignment to each event of a mark, that is its magnitude, modelled through a distribution that depends
at timet on the stress level accumulated up to that instant. The resulting parameter space is constrained and dependent on the data,
complicating Bayesian computation and analysis. We have resorted to Monte Carlo methods to solve these problems. 相似文献
58.
Christian P. Robert Xiao-Li Meng Jesper Møller Jeffrey S Rosenthal C Jennison M. A Hurn F Al-Awadhi Peter McCullagh Christophe Andrieu Arnaud Doucet Petros Dellaportas Ioulia Papageorgiou Ricardo S Ehlers Elena A Erosheva Stephen E Fienberg Jonathan J Forster Roger C Gill Nial Friel Peter Green David Hastie R King Hans R Künsch N. A. Lazar C Osinski 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2003,65(1):39-55
59.
Cathy W. S. Chen F. C. Liu Mike K. P. So 《Australian & New Zealand Journal of Statistics》2008,50(1):29-51
To capture mean and variance asymmetries and time‐varying volatility in financial time series, we generalize the threshold stochastic volatility (THSV) model and incorporate a heavy‐tailed error distribution. Unlike existing stochastic volatility models, this model simultaneously accounts for uncertainty in the unobserved threshold value and in the time‐delay parameter. Self‐exciting and exogenous threshold variables are considered to investigate the impact of a number of market news variables on volatility changes. Adopting a Bayesian approach, we use Markov chain Monte Carlo methods to estimate all unknown parameters and latent variables. A simulation experiment demonstrates good estimation performance for reasonable sample sizes. In a study of two international financial market indices, we consider two variants of the generalized THSV model, with US market news as the threshold variable. Finally, we compare models using Bayesian forecasting in a value‐at‐risk (VaR) study. The results show that our proposed model can generate more accurate VaR forecasts than can standard models. 相似文献
60.
Michael S. Rendall Ryan Admiraal Alessandra DeRose Paola DiGiulio Mark S. Handcock Filomena Racioppi 《Statistical Methods and Applications》2008,17(4):519-539
In non-experimental research, data on the same population process may be collected simultaneously by more than one instrument.
For example, in the present application, two sample surveys and a population birth registration system all collect observations
on first births by age and year, while the two surveys additionally collect information on women’s education. To make maximum
use of the three data sources, the survey data are pooled and the population data introduced as constraints in a logistic
regression equation. Reductions in standard errors about the age and birth-cohort parameters of the regression equation in
the order of three-quarters are obtained by introducing the population data as constraints. A halving of the standard errors
about the education parameters is achieved by pooling observations from the larger survey dataset with those from the smaller
survey. The percentage reduction in the standard errors through imposing population constraints is independent of the total
survey sample size. 相似文献