全文获取类型
收费全文 | 7844篇 |
免费 | 275篇 |
国内免费 | 176篇 |
专业分类
管理学 | 1176篇 |
劳动科学 | 2篇 |
民族学 | 22篇 |
人才学 | 2篇 |
人口学 | 501篇 |
丛书文集 | 409篇 |
理论方法论 | 784篇 |
综合类 | 2891篇 |
社会学 | 2311篇 |
统计学 | 197篇 |
出版年
2024年 | 18篇 |
2023年 | 131篇 |
2022年 | 93篇 |
2021年 | 137篇 |
2020年 | 259篇 |
2019年 | 271篇 |
2018年 | 294篇 |
2017年 | 392篇 |
2016年 | 271篇 |
2015年 | 247篇 |
2014年 | 374篇 |
2013年 | 1563篇 |
2012年 | 393篇 |
2011年 | 429篇 |
2010年 | 311篇 |
2009年 | 310篇 |
2008年 | 347篇 |
2007年 | 376篇 |
2006年 | 391篇 |
2005年 | 301篇 |
2004年 | 290篇 |
2003年 | 210篇 |
2002年 | 204篇 |
2001年 | 147篇 |
2000年 | 107篇 |
1999年 | 73篇 |
1998年 | 44篇 |
1997年 | 51篇 |
1996年 | 30篇 |
1995年 | 27篇 |
1994年 | 44篇 |
1993年 | 19篇 |
1992年 | 22篇 |
1991年 | 17篇 |
1990年 | 12篇 |
1989年 | 11篇 |
1988年 | 21篇 |
1987年 | 14篇 |
1986年 | 11篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1979年 | 1篇 |
排序方式: 共有8295条查询结果,搜索用时 15 毫秒
11.
Beryllium is the strongest of the lightweight metals. Used primarily in military applications prior to the end of the Cold War, beryllium is finding new applications in many commercial products, including computers, telecommunication equipment, and consumer and automotive electronics. The use of beryllium in nondefense consumer applications is of concern because beryllium is toxic. Inhalation of beryllium dust or vapor causes a chronic lung disease in some individuals at concentrations as low as 0.01 microg/m3 in air. As beryllium enters wider commerce, it is prudent to ask what risks this might present to the general public and to workers downstream of the beryllium materials industry. We address this question by evaluating the potential for beryllium exposure from the manufacturing, use, recycle, and disposal of beryllium-containing products. Combining a market study with a qualitative exposure analysis, we determine which beryllium applications and life cycle phases have the largest exposure potential. Our analysis suggests that use and maintenance of the most common types of beryllium-containing products do not result in any obvious exposures of concern, and that maintenance activities result in greater exposures than product use. Product disposal has potential to present significant individual risks, but uncertainties concerning current and future routes of product disposal make it difficult to be definitive. Overall, additional exposure and dose-response data are needed to evaluate both the health significance of many exposure scenarios, and the adequacy of existing regulations to protect workers and the public. Although public exposures to beryllium and public awareness and concern regarding beryllium risks are currently low, beryllium risks have psychometric qualities that may lead to rapidly heightened public concern. 相似文献
12.
Charles W. Griffiths Chris Dockins Nicole Owens Nathalie B. Simon Daniel A. Axelrad 《Risk analysis》2002,22(4):679-688
To quantify the health benefits of environmental policies, economists generally require estimates of the reduced probability of illness or death. For policies that reduce exposure to carcinogenic substances, these estimates traditionally have been obtained through the linear extrapolation of experimental dose-response data to low-exposure scenarios as described in the U.S. Environmental Protection Agency's Guidelines for Carcinogen Risk Assessment (1986). In response to evolving scientific knowledge, EPA proposed revisions to the guidelines in 1996. Under the proposed revisions, dose-response relationships would not be estimated for carcinogens thought to exhibit nonlinear modes of action. Such a change in cancer-risk assessment methods and outputs will likely have serious consequences for how benefit-cost analyses of policies aimed at reducing cancer risks are conducted. Any tendency for reduced quantification of effects in environmental risk assessments, such as those contemplated in the revisions to EPA's cancer-risk assessment guidelines, impedes the ability of economic analysts to respond to increasing calls for benefit-cost analysis. This article examines the implications for benefit-cost analysis of carcinogenic exposures of the proposed changes to the 1986 Guidelines and proposes an approach for bounding dose-response relationships when no biologically based models are available. In spite of the more limited quantitative information provided in a carcinogen risk assessment under the proposed revisions to the guidelines, we argue that reasonable bounds on dose-response relationships can be estimated for low-level exposures to nonlinear carcinogens. This approach yields estimates of reduced illness for use in a benefit-cost analysis while incorporating evidence of nonlinearities in the dose-response relationship. As an illustration, the bounding approach is applied to the case of chloroform exposure. 相似文献
13.
Casey Crump Kenny Crump Eric Hack Rose Luippold Kenneth Mundt Elizabeth Liebig Julie Panko Dennis Paustenbach Deborah Proctor 《Risk analysis》2003,23(6):1147-1163
This study evaluates the dose-response relationship for inhalation exposure to hexavalent chromium [Cr(VI)] and lung cancer mortality for workers of a chromate production facility, and provides estimates of the carcinogenic potency. The data were analyzed using relative risk and additive risk dose-response models implemented with both Poisson and Cox regression. Potential confounding by birth cohort and smoking prevalence were also assessed. Lifetime cumulative exposure and highest monthly exposure were the dose metrics evaluated. The estimated lifetime additional risk of lung cancer mortality associated with 45 years of occupational exposure to 1 microg/m3 Cr(VI) (occupational exposure unit risk) was 0.00205 (90%CI: 0.00134, 0.00291) for the relative risk model and 0.00216 (90%CI: 0.00143, 0.00302) for the additive risk model assuming a linear dose response for cumulative exposure with a five-year lag. Extrapolating these findings to a continuous (e.g., environmental) exposure scenario yielded an environmental unit risk of 0.00978 (90%CI: 0.00640, 0.0138) for the relative risk model [e.g., a cancer slope factor of 34 (mg/kg-day)-1] and 0.0125 (90%CI: 0.00833, 0.0175) for the additive risk model. The relative risk model is preferred because it is more consistent with the expected trend for lung cancer risk with age. Based on statistical tests for exposure-related trend, there was no statistically significant increased lung cancer risk below lifetime cumulative occupational exposures of 1.0 mg-yr/m3, and no excess risk for workers whose highest average monthly exposure did not exceed the current Permissible Exposure Limit (52 microg/m3). It is acknowledged that this study had limited power to detect increases at these low exposure levels. These cancer potency estimates are comparable to those developed by U.S. regulatory agencies and should be useful for assessing the potential cancer hazard associated with inhaled Cr(VI). 相似文献
14.
We discuss the issue of using benchmark doses for quantifying (excess) risk associated with exposure to environmental hazards. The paradigm of low-dose risk estimation in dose-response modeling is used as the primary application scenario. Emphasis is placed on making simultaneous inferences on benchmark doses when data are in the form of proportions, although the concepts translate easily to other forms of outcome data. 相似文献
15.
范群 陈永年 连燕舒 刘建华 方明明 陈峰 吉华萍 吴丽平 李学信 许婷 FAN Qun CHEN Yong-nian LIAN Yan-shu LIU Jian-hu FANG Ming-ming CHEN Feng JI Hua-ping WU Li-ping LI Xue-xin XU Ting 《南京医科大学学报(社会科学版)》2006,6(1):57-60
目的:比较社区卫生服务中心及各级医院常见手术费用;社区卫生服务中心手术是否便捷、低耗,有无保留的必要。方法:调研南京市社区卫生服务中心及各级医院常见手术的单病种费用,社区卫生服务中心与各级医院的费用做统计分析比较。结果:社区卫生服务中心单病种手术平均住院费用明显低于与各级医院。结论:从经济学的角度分析,各级医院手术费用差别很大,在规范和安全的前提下,社区卫生服务中心保留基本的手术功能是符合社区居民需求和社区卫生服务自身发展需要的。 相似文献
16.
福州市社区空巢老年人健康状况调查 总被引:9,自引:0,他引:9
目的了解空巢老年人的健康现状及其影响因素,为老龄工作提供科学依据。方法2002年4~5月进行入户调查,采用分层整群抽取福州市鼓楼、台江、仓山三个区60岁及以上的社区老年人,共得到有效样本1767例,其中空巢老人696名。空巢老人躯体健康、生活自理能力(ADL)、经济状况、精神健康、社会健康5个维度的健康状况及其影响因素的调查是本次研究的主要内容。结果福州市社区空巢老年人占老年人总体比例的39%,其中男性多于女性;由logistic检验得出空巢老年人健康状况受年龄、性别、原职业、是否赞成非家庭养老方式、锻炼程度等因素的影响。结论倡导空巢老年人形成良好的生活饮食习惯与自我保健意识,加强对空巢老年人慢性病的防治,丰富老年人的精神生活、社会生活,提高对空巢老年人经济支持,完善社区为老服务,从而改善空巢老年人的健康状况。 相似文献
17.
18.
生态运动与绿色主义福利思想:生态健康科学与新型公共卫生框架 总被引:1,自引:0,他引:1
刘继同 《北京科技大学学报(社会科学版)》2005,21(3):66-70
人与自然、社会与自然关系既是经典的理论议题,又是紧迫重大的现实政策问题.本文从生态运动入手,系统介绍作为生态运动理论基础的绿色福利主义,并以生态健康科学为基本理论视角,简要探讨新型现代公共卫生政策框架及其革命性的现实、理论与政策涵义. 相似文献
19.
Brian D. Loader Steve Muncer Roger Burrows Nicholas Pleace & Sara Nettleton 《International Journal of Social Welfare》2002,11(1):53-65
The advent of thousands of Usenet groups on the Internet, covering a vast range of medical and welfare issues and ostensibly devoted to the mutual social support of participating members, has raised the potential for the development of new forms of 'virtual' health care. This article critically analyses the use by people with diabetes of one such Usenet group. It seeks to establish, first, the extent to which such a site provides some demonstrable measure of social support to its participants. This is approached by undertaking a structural analysis of the site to identify the extent of usage, and the nature of supporting interventions using a fivefold classification (instrumental, informational, esteem and social companionship and other). Second, the article attempts to identify any disparity between the lay health-knowledge in evidence and biomedical opinions proffered by the use of a panel of consultant diabetiologists. The results of the analysis suggest that the diabetes newsgroup provides an example of an active forum for largely well-informed participants who routinely use the media as an aid to the reflexive management of their medical condition. It also raises the prospect of a renegotiated relationship between medical knowledge and lay experience based upon shared learning 相似文献
20.
上海市空气污染造成人群健康经济损失的研究 总被引:4,自引:0,他引:4
文章通过对上海市空气污染季节性状况的描述 ,分析了各种污染物的污染程度和变化趋势 ,并利用对上海某市级医院的实地调查数据 ,对空气污染物与医院呼吸系统疾病患者日门诊量之间的相关关系进行研讨 ,建立了多元分析模型 ,探讨了患者健康经济损失的计量方法 ,并对由空气污染造成呼吸系统疾病患者健康经济损失进行了估算。研究表明 ,在其他条件不变的情况下 ,NOX 日指数每增长 10 % ,被调查医院呼吸系统疾病患者的日门诊人次增加 7 7人次 ,而这些疾病患者由于患病产生的年度健康经济损失为 2 11万元。据此作保守的推断估计 ,上海市一年内因NOX 超标而发生的呼吸系统疾病门诊行为造成的健康经济损失可以达到 4 2亿元。同样 ,SO2 和TSP造成门诊患者的健康经济损失分别为 1 5亿元和 0 86亿元 相似文献