首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   13798篇
  免费   608篇
  国内免费   226篇
管理学   1518篇
劳动科学   2篇
民族学   47篇
人才学   3篇
人口学   540篇
丛书文集   1002篇
理论方法论   912篇
综合类   7656篇
社会学   2722篇
统计学   230篇
  2024年   37篇
  2023年   179篇
  2022年   149篇
  2021年   213篇
  2020年   341篇
  2019年   347篇
  2018年   369篇
  2017年   484篇
  2016年   378篇
  2015年   398篇
  2014年   678篇
  2013年   1887篇
  2012年   706篇
  2011年   842篇
  2010年   618篇
  2009年   640篇
  2008年   728篇
  2007年   839篇
  2006年   827篇
  2005年   737篇
  2004年   675篇
  2003年   654篇
  2002年   564篇
  2001年   446篇
  2000年   293篇
  1999年   135篇
  1998年   69篇
  1997年   62篇
  1996年   44篇
  1995年   39篇
  1994年   61篇
  1993年   25篇
  1992年   32篇
  1991年   21篇
  1990年   18篇
  1989年   15篇
  1988年   21篇
  1987年   17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10000条查询结果,搜索用时 31 毫秒
61.
目的:考察主动到心理咨询中心求助的大学生自我表露和孤独状况并与普通大学生的资料进行比较;考察来访者对咨询员的自我表露与其他目标人的表露之差异。结果发现:求询大学生与普通大学生的自我表露相比显著地低;求询大学生对咨询员的表露比其他目标人的表露显著地高;求询大学生的孤独感明显地高于普通大学生;心理咨询在大学生发展过程中起着重要的作用。  相似文献   
62.
企业改制是建立现代企业制度的必要途径。资产评估是企业改制中必不可少的重要环节。资产评估应明确评估目的、评估基准期、评估对象 ,掌握正确的评估方法和规范的评估程序。在企业改制中要特别注意设计稳妥的剥离方法 ,对非经营性资产和非经营性人员进行合理的剥离  相似文献   
63.
Summary Based on 14 case studies of highly effective therapies and the reasons they succeeded less frequently than they could, we propose a variety of steps to improve the health care system of the U.S.A. Whatever proposal emerges from current national debates until innovations are shown to be safe and effective, they should not be supported; when slightly better technologies are much more expensive than other good ones we need to consider appropriate choices carefully; simplified billing and bookkeping would reduce our costs; when a technology is rapidly introduced cautionnary measures may be needed; tracking immunization and repairing their omissions requires a new system; educational programs such as seen effective in hypertension should be applied in other areas such as vaccination; in organ transplantation the nation should consider “presumed consent”; our payment system sometimes creates perverse incentives and therefore needs review; and the preferences of the public in allocation of health resources need to be discovered once the public is informed about the issues. Research supported by Andrew W. Mellon Foundation.  相似文献   
64.
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   
65.
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   
66.
科技特派员制度生命力的探析   总被引:5,自引:0,他引:5  
地处闽北的南平市在发展当地经济、促进农业重大转型的特定时期,启动科技特派员制度,有其深刻的时代背景和现实意义。本文从科技特派员制度创举与活力切入,分析这一制度创举深层次的原因,并进一步探讨这一制度生命力如何在新时期持续和创新。  相似文献   
67.
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   
68.
基因序列的可专利性研究   总被引:1,自引:0,他引:1  
从基因序列的发明发现之争、基因序列的创造性和实用性分析、基因序列专利保护对社会公共利益的影响三个方面出发,对基因序列的专利保护问题进行了深入具体的分析探讨,最终发现:从理论上讲,没有足够充分的理由阻止基因序列的专利保护,但是各国对基因序列的专利保护应当根据本国基因资源拥有、生物科技的发展等具体情况而定。  相似文献   
69.
与那些重点综合性大学和师范类高校的文科学报相比,理工农医院校的文科学报存在诸多的发展制约因素:学报发展缺乏强势学科的支撑;学报的稿源不够理想;学校对学报重视不够,编辑人员的结构不够合理;办刊模式僵化,缺少个性和特色。理工农医高校文科学报要突破各种阻碍学报发展的制约因素,就要更新观念,大胆变革,锐意创新,不断探索期刊发展的新路。  相似文献   
70.
在社会实践活动中,科学技术引导人在真、善、美三个方面充分展现自己的本性和才能,是人发展与完善自身的内在动力。由于科技发展与人的社会责任、知识成果运用的动机与效果之间存在可能的冲突,科技发展对人的发展也具有否定性影响。必须对科技活动的主体提出自我调适的要求,促进人类健康发展。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号