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   34265篇
  免费   1075篇
  国内免费   103篇
管理学   3588篇
劳动科学   38篇
民族学   532篇
人才学   25篇
人口学   2117篇
丛书文集   4857篇
教育普及   2篇
理论方法论   2401篇
现状及发展   1篇
综合类   7206篇
社会学   10068篇
统计学   4608篇
  2023年   138篇
  2022年   293篇
  2021年   355篇
  2020年   469篇
  2019年   523篇
  2018年   635篇
  2017年   952篇
  2016年   720篇
  2015年   810篇
  2014年   981篇
  2013年   3739篇
  2012年   1457篇
  2011年   1739篇
  2010年   1641篇
  2009年   1606篇
  2008年   1566篇
  2007年   1687篇
  2006年   1752篇
  2005年   1447篇
  2004年   947篇
  2003年   784篇
  2002年   944篇
  2001年   954篇
  2000年   806篇
  1999年   696篇
  1998年   483篇
  1997年   462篇
  1996年   484篇
  1995年   427篇
  1994年   366篇
  1993年   364篇
  1992年   413篇
  1991年   359篇
  1990年   329篇
  1989年   309篇
  1988年   309篇
  1987年   264篇
  1986年   247篇
  1985年   282篇
  1984年   271篇
  1983年   252篇
  1982年   219篇
  1981年   185篇
  1980年   166篇
  1979年   194篇
  1978年   176篇
  1977年   159篇
  1976年   134篇
  1975年   157篇
  1974年   118篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
国际组织的语言选择是其行政机构及成员基于组织特性、语言价值等多种考量因素进行博弈的结果。为实现国际组织的宗旨和目标,其行政机构基于国际组织的“组织性”特征尤为注重语言的实用价值,甚至以此作为主导性考量因素,英语因而在国际组织的语言选择中占据主导地位。然而,“国际性”特征要求国际组织必须兼顾语言的象征价值,这与其成员彰显本国语言的诉求相吻合。国际组织成员尤其是成员国的权力强弱对国际组织的语言选择影响深远,部分成员通过在特定国际组织中推广本国语言的使用来提高自身的国际地位及影响力。同时,历史因素通过保留国际组织权力结构中的正式制度对其语言选择产生延迟性影响,致使语言政策的变革滞后于成员之间的相对权力动态。  相似文献   
2.
Damage models for natural hazards are used for decision making on reducing and transferring risk. The damage estimates from these models depend on many variables and their complex sometimes nonlinear relationships with the damage. In recent years, data‐driven modeling techniques have been used to capture those relationships. The available data to build such models are often limited. Therefore, in practice it is usually necessary to transfer models to a different context. In this article, we show that this implies the samples used to build the model are often not fully representative for the situation where they need to be applied on, which leads to a “sample selection bias.” In this article, we enhance data‐driven damage models by applying methods, not previously applied to damage modeling, to correct for this bias before the machine learning (ML) models are trained. We demonstrate this with case studies on flooding in Europe, and typhoon wind damage in the Philippines. Two sample selection bias correction methods from the ML literature are applied and one of these methods is also adjusted to our problem. These three methods are combined with stochastic generation of synthetic damage data. We demonstrate that for both case studies, the sample selection bias correction techniques reduce model errors, especially for the mean bias error this reduction can be larger than 30%. The novel combination with stochastic data generation seems to enhance these techniques. This shows that sample selection bias correction methods are beneficial for damage model transfer.  相似文献   
3.
科技创新能够通过产业复杂度的变化对经济增长产生影响.以1995—2019年世界银行和哈佛大学Atlas数据库的科技创新为研究样本,运用中介效应检验方法,考察科技创新如何通过纺织类、农业类、钻石类、矿产类、金属类、化工类、汽车类、设备类和电子类的产业复杂度变化来影响国民生产总值,从而揭示了科技创新如何通过产业复杂度的变化影响经济增长的机理.研究结果表明:从总体上看,科技创新影响经济增长的过程中,产业复杂度的中介效应量为90.83%,具有显著性,其中农业类、钻石类以及矿产类相关系数为负,其他类别相关系数为正,电子类作用程度最高.区分经济体类型的研究结果显示:产业复杂度的中介效应存在异质性,发达经济体、亚洲经济体、技术密集型经济体存在相对优势,而且科技创新促进经济增长开启了"机会窗口期",后发经济体可以实现"弯道超车".这一研究结论有助于丰富科技创新领域的相关成果,能够为引导产业转型升级方向、提高国家经济增长能力提供理论依据和经验借鉴.  相似文献   
4.
5.

Motivated by a breast cancer research program, this paper is concerned with the joint survivor function of multiple event times when their observations are subject to informative censoring caused by a terminating event. We formulate the correlation of the multiple event times together with the time to the terminating event by an Archimedean copula to account for the informative censoring. Adapting the widely used two-stage procedure under a copula model, we propose an easy-to-implement pseudo-likelihood based procedure for estimating the model parameters. The approach yields a new estimator for the marginal distribution of a single event time with semicompeting-risks data. We conduct both asymptotics and simulation studies to examine the proposed approach in consistency, efficiency, and robustness. Data from the breast cancer program are employed to illustrate this research.

  相似文献   
6.
Organizational scholars increasingly recognize the value of employing historical research. Yet the fields of history and organization studies struggle to reconcile. In this paper, the authors contend that a closer connection between these two fields is possible if organizational historians bring their role in the construction of historical narratives to the fore and open up their research decisions for discussion. They provide guidelines to support this endeavor, drawing on four criteria that are prevalent within interpretive organization studies for developing the trustworthiness of research: credibility; confirmability; dependability; and transferability. In contrast to the traditional use of trustworthiness criteria to evaluate the quality of research, the authors advance the criteria to encourage historians to generate more transparent narratives. Such transparency allows others to comprehend and comment on the construction of narratives, thereby building trust and understanding. Each criterion is converted into a set of guiding principles to enhance the trustworthiness of historical research, pairing each principle with a practical technique gleaned from a range of disciplines within the social sciences to provide practical guidance.  相似文献   
7.
8.
9.
We employ two population‐level experiments to accurately measure opposition to immigration before and after the economic crisis of 2008. Our design explicitly addresses social desirability bias, which is the tendency to give responses that are seen favorably by others and can lead to substantial underreporting of opposition to immigration. We find that overt opposition to immigration, expressed as support for a closed border, increases slightly after the crisis. However, once we account for social desirability bias, no significant increase remains. We conclude that the observed increase in anti‐immigration sentiment in the post‐crisis United States is attributable to greater expression of opposition rather than any underlying change in attitudes.  相似文献   
10.
针对磷酸酯/Al3+ 交联的油基压裂液交联速度慢,交联剂溶解性慢、稳定性差和价格高等缺点,首次对磷酸酯/Fe3+ 交联的油基压裂液体系进行了研究。通过对铁交联剂体系的优化,筛选一种磷酸酯/Fe3+ 交联的新型交联剂体系,并对磷酸酯/Fe3+ 油基冻胶压裂液性能进行了评价。结果表明:采用30%Fe2(SO4)3+15% 二乙醇胺+55% 水制备的新型交联剂体系,直接与磷酸酯混合即可形成油基冻胶,其性能不受放置时间的影响,交联速度快,成胶性能好,10 min 就可达到最大黏度;压裂液的抗温抗剪切性能高,与常规铝交联剂体系比较,压裂液成胶速度提高了20 倍,压裂液的抗温能力由原来100 ℃提高到135 ℃,并且压裂液的破胶性和滤失性等性能均能达到压裂施工的要求。  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