全文获取类型
收费全文 | 1796篇 |
免费 | 101篇 |
国内免费 | 11篇 |
专业分类
管理学 | 137篇 |
民族学 | 8篇 |
人才学 | 1篇 |
人口学 | 40篇 |
丛书文集 | 112篇 |
理论方法论 | 114篇 |
综合类 | 975篇 |
社会学 | 98篇 |
统计学 | 423篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 21篇 |
2021年 | 18篇 |
2020年 | 27篇 |
2019年 | 52篇 |
2018年 | 33篇 |
2017年 | 49篇 |
2016年 | 45篇 |
2015年 | 55篇 |
2014年 | 95篇 |
2013年 | 196篇 |
2012年 | 110篇 |
2011年 | 110篇 |
2010年 | 93篇 |
2009年 | 107篇 |
2008年 | 104篇 |
2007年 | 87篇 |
2006年 | 109篇 |
2005年 | 70篇 |
2004年 | 68篇 |
2003年 | 56篇 |
2002年 | 68篇 |
2001年 | 70篇 |
2000年 | 41篇 |
1999年 | 28篇 |
1998年 | 23篇 |
1997年 | 26篇 |
1996年 | 26篇 |
1995年 | 8篇 |
1994年 | 18篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有1908条查询结果,搜索用时 31 毫秒
41.
In late 2009 China launched an innovative, voluntary programme that by 2011 had extended pension coverage to 326.4 million people in the rural sector, including contributors and beneficiaries. It requires one contribution per year and provides a flat‐rate benefit and a contributions‐related benefit through a contributory individual account, with a government guarantee that the benefit will continue for life. The programme encourages participation of persons who do not pay income taxes, and thus have no tax incentive to participate, by providing substantial government subsidies. As a further incentive, old‐age benefits are provided to older parents when all their adult children participate in the contributory programme. 相似文献
42.
43.
Using In Vitro High‐Throughput Screening Data for Predicting Benzo[k]Fluoranthene Human Health Hazards
下载免费PDF全文
![点击此处可从《Risk analysis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Today there are more than 80,000 chemicals in commerce and the environment. The potential human health risks are unknown for the vast majority of these chemicals as they lack human health risk assessments, toxicity reference values, and risk screening values. We aim to use computational toxicology and quantitative high‐throughput screening (qHTS) technologies to fill these data gaps, and begin to prioritize these chemicals for additional assessment. In this pilot, we demonstrate how we were able to identify that benzo[k]fluoranthene may induce DNA damage and steatosis using qHTS data and two separate adverse outcome pathways (AOPs). We also demonstrate how bootstrap natural spline‐based meta‐regression can be used to integrate data across multiple assay replicates to generate a concentration–response curve. We used this analysis to calculate an in vitro point of departure of 0.751 μM and risk‐specific in vitro concentrations of 0.29 μM and 0.28 μM for 1:1,000 and 1:10,000 risk, respectively, for DNA damage. Based on the available evidence, and considering that only a single HSD17B4 assay is available, we have low overall confidence in the steatosis hazard identification. This case study suggests that coupling qHTS assays with AOPs and ontologies will facilitate hazard identification. Combining this with quantitative evidence integration methods, such as bootstrap meta‐regression, may allow risk assessors to identify points of departure and risk‐specific internal/in vitro concentrations. These results are sufficient to prioritize the chemicals; however, in the longer term we will need to estimate external doses for risk screening purposes, such as through margin of exposure methods. 相似文献
44.
David E. Bloom Mathew J. McKenna Klaus Prettner 《International social security review》2019,72(3):43-78
Globally, an estimated 734 million jobs will be required between 2010 and 2030 to accommodate recent and ongoing demographic shifts, account for plausible changes in labour force participation rates, and achieve target unemployment rates of at or below 4 per cent for adults and at or below 8 per cent for youth. The facts that most new jobs will be required in countries where “decent” jobs are less prevalent and workers in many occupations are increasingly subject to risks of automation further compound the challenge of job creation, which is already quite sizable in historical perspective. Failure to create the jobs that are needed through 2030 would put currently operative social security systems under pressure and undermine efforts to guarantee the national social protection floors enshrined in the Sustainable Development Goals (SDGs). 相似文献
45.
摘 要:应用儿童长处与困难(SDQ)问卷(父母版),采用分层随机抽样方法,对惠州市1528名3-6岁儿童的情绪与行为问题进行调查。研究发现:惠州市3-6岁儿童情绪与行为问题异常情况比较严峻,儿童心理健康状况值得重视;不同地域、年龄学前儿童存在不同的情绪与行为问题,需要分类干预。其中农村儿童的情绪与行为问题异常情况尤为严重,需要得到广泛的关注和解决。 相似文献
46.
Tobias A. Möller 《随机性模型》2016,32(1):77-98
In this article, an integer-valued self-exciting threshold model with a finite range based on the binomial INARCH(1) model is proposed. Important stochastic properties are derived, and approaches for parameter estimation are discussed. A real-data example about the regional spread of public drunkenness in Pittsburgh demonstrates the applicability of the new model in comparison to existing models. Feasible modifications of the model are presented, which are designed to handle special features such as zero-inflation. 相似文献
47.
In this paper, we demonstrate how public opinion surveys can be designed to collect information pertinent to computational behavior modeling, and we present the results of a public opinion and behavior survey conducted during the 2009–2010 H1N1 influenza pandemic. The results are used to parameterize the Health Belief Model of individual health‐protective decision making. Survey subjects were asked questions about their perceptions of the then‐circulating influenza and attitudes towards two personal protective behaviors: vaccination and avoidance of crowds. We empirically address two important issues in applying the Health Belief Model of behavior to computational infectious disease simulation: (1) the factors dynamically influencing the states of the Health Belief Model variables and (2) the appropriateness of the Health Belief Model in describing self‐protective behavior in the context of pandemic influenza. 相似文献
48.
Angela Swift Joan Webster Annette Mary Conroy Sue Hampton Sarah Jane Kirby Lee Minuzzo Rebecca Kimble 《Women and birth : journal of the Australian College of Midwives》2014,27(3):163-167
BackgroundSevere perineal tears sustained during childbirth cause significant distress and morbidity amongst women. The objective of this study was to compare the use of straight scissors for cutting an episiotomy with the use of curved scissors, which are designed to curve away from the anal sphincter.MethodsWe used a single-centre, randomised feasibility trial. The intervention was the use of curved scissors. Women were recruited during a prenatal visit and randomised in the delivery suite, when it became clear that an episiotomy was required. The feasibility outcomes were the proportion of women able to be recruited, randomised and followed up. We also calculated the incidence of obstetric anal sphincter injury when either straight or curved scissors were used to cut an episiotomy. Other outcomes assessed were pain, length of hospital stay, perineal infection and perineal dehiscence.ResultsOf the 155 patients recruited in the prenatal period, only 20 (12.9%) were eventually randomised at birth. The main reasons for the high loss were that women either did not have a vaginal delivery (38, 24.5%), or they did not need an episiotomy (72, 46.5%). Rates of obstetric anal sphincter injury and other outcomes were similar between groups.DiscussionAnal sphincter injury during childbirth remains an important problem. Although the use of curved scissors provides a theoretical solution, we found that the high attrition rate made feasibility of conducting a suitably powered, randomised trial using the current design untenable. Alternative strategies have been suggested to make any future study more viable. 相似文献
49.
《Journal of Statistical Computation and Simulation》2012,82(1-2):63-68
A number of efficient computer codes are available for the simple linear L 1 regression problem. However, a number of these codes can be made more efficient by utilizing the least squares solution. In fact, a couple of available computer programs already do so. We report the results of a computational study comparing several openly available computer programs for solving the simple linear L 1 regression problem with and without computing and utilizing a least squares solution. 相似文献
50.
Methods for a sequential test of a dose-response effect in pre-clinical studies are investigated. The objective of the test procedure is to compare several dose groups with a zero-dose control. The sequential testing is conducted within a closed family of one-sided tests. The procedures investigated are based on a monotonicity assumption. These closed procedures strongly control the familywise error rate while providing information about the shape of the dose-responce relationship. Performance of sequential testing procedures are compared via a Monte Carlo simulation study. We illustrae the procedures by application to a real data set. 相似文献