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   2552篇
  免费   58篇
  国内免费   4篇
管理学   306篇
劳动科学   3篇
民族学   48篇
人才学   1篇
人口学   127篇
丛书文集   185篇
理论方法论   234篇
综合类   556篇
社会学   855篇
统计学   299篇
  2023年   15篇
  2022年   13篇
  2021年   21篇
  2020年   40篇
  2019年   55篇
  2018年   50篇
  2017年   69篇
  2016年   54篇
  2015年   64篇
  2014年   91篇
  2013年   301篇
  2012年   108篇
  2011年   126篇
  2010年   108篇
  2009年   106篇
  2008年   109篇
  2007年   107篇
  2006年   118篇
  2005年   84篇
  2004年   81篇
  2003年   100篇
  2002年   143篇
  2001年   111篇
  2000年   68篇
  1999年   46篇
  1998年   33篇
  1997年   35篇
  1996年   20篇
  1995年   24篇
  1994年   25篇
  1993年   14篇
  1992年   12篇
  1991年   18篇
  1990年   15篇
  1989年   7篇
  1988年   24篇
  1987年   15篇
  1986年   18篇
  1985年   15篇
  1984年   18篇
  1983年   15篇
  1982年   11篇
  1981年   21篇
  1980年   16篇
  1979年   13篇
  1978年   11篇
  1977年   6篇
  1976年   8篇
  1975年   9篇
  1974年   7篇
排序方式: 共有2614条查询结果,搜索用时 9 毫秒
941.
This paper examines the absorption of foreign aid in the presence of formal and informal production. Calibrating a two-sector open economy model to 67 aid-recipient countries for 1990–2019, we show that an increase in foreign aid drives resources into the informal sector, and away from the formal sector. With untied aid, the expansion of the informal sector can lead to an economic contraction through the Dutch Disease effect. An economic expansion with an increase in the share of formal production can be attained by re-allocating existing aid to public investment rather than an increase in the aggregate level of aid.  相似文献   
942.
Journal of Nonverbal Behavior - Facial expressions contribute to nonverbal communication, social coordination, and interaction. Facial expressions may reflect the emotional state of the expressor,...  相似文献   
943.
Caregiver voices may provide cues to mobilize or calm infants. This study examined whether maternal prosody predicted changes in infants’ biobehavioral state after the still face, a stressor in which the mother withdraws and reinstates social engagement. Ninety-four dyads participated in the study (infant age 4–8 months). Infants’ heart rate and respiratory sinus arrhythmia (measuring cardiac vagal tone) were derived from an electrocardiogram (ECG). Infants’ behavioral distress was measured by negative vocalizations, facial expressions, and gaze aversion. Mothers’ vocalizations were measured via a composite of spectral analysis and spectro-temporal modulation using a two-dimensional fast Fourier transformation of the audio spectrogram. High values on the maternal prosody composite were associated with decreases in infants’ heart rate (β = ?.26, 95% CI: [?0.46, ?0.05]) and behavioral distress (β = ?.23, 95% CI: [?0.42, ?0.03]), and increases in cardiac vagal tone in infants whose vagal tone was low during the stressor (1 SD below mean β = .39, 95% CI: [0.06, 0.73]). High infant heart rate predicted increases in the maternal prosody composite (β = .18, 95% CI: [0.03, 0.33]). These results suggest specific vocal acoustic features of speech that are relevant for regulating infants’ biobehavioral state and demonstrate mother–infant bi-directional dynamics.  相似文献   
944.
The edit distance under the DCJ model can be computed in linear time for genomes with equal content or with Indels. But it becomes NP-Hard in the presence of duplications, a problem largely unsolved especially when Indels (i.e., insertions and deletions) are considered. In this paper, we compare two mainstream methods to deal with duplications and associate them with Indels: one by deletion, namely DCJ-Indel-Exemplar distance; versus the other by gene matching, namely DCJ-Indel-Matching distance. We design branch-and-bound algorithms with set of optimization methods to compute exact distances for both. Furthermore, median problems are discussed in alignment with both of these distance methods, which are to find a median genome that minimizes distances between itself and three given genomes. Lin–Kernighan heuristic is leveraged and powered up by sub-graph decomposition and search space reduction technologies to handle median computation. A wide range of experiments are conducted on synthetic data sets and real data sets to exhibit pros and cons of these two distance metrics per se, as well as putting them in the median computation scenario.  相似文献   
945.
Carpooling is a flexible shared transportation system which can effectively reduce the vehicle numbers and fuel consumption. Although many carpooling systems have been proposed, most of them lack practicality, veracity, and efficiency. In this paper, we propose a new useful variant model of the long-term carpooling problem which involves multiple origins and one destination. Such problems commonly occur in a wide number of carpooling situations in real-world scenarios. Our work is motivated by the practical needs to solve environmental pollution, parking problems, traffic jams and low utilization of resources. A Tabu search algorithm is proposed in this paper to solve the carpooling problem. The proposed algorithm aims at a wide range of passenger distribution and routing problems. The computational results based on real world user data show the effectiveness of the proposed algorithm. Moreover, we developed a mobile application based on our carpooling model.  相似文献   
946.
本研究以2014年 APEC 会议外围区域志愿者为调查对象,从性别、报名渠道、学历、志愿服务次数等维度,通过调查问卷的形式,研究志愿者在沟通姿态、自我状态、动机三方面的不同表现,并进一步解释三者之间的相关情况,为改进和完善志愿者的招募、管理、教育等方面提供了依据。  相似文献   
947.
Clinical trials in the era of precision cancer medicine aim to identify and validate biomarker signatures which can guide the assignment of individually optimal treatments to patients. In this article, we propose a group sequential randomized phase II design, which updates the biomarker signature as the trial goes on, utilizes enrichment strategies for patient selection, and uses Bayesian response-adaptive randomization for treatment assignment. To evaluate the performance of the new design, in addition to the commonly considered criteria of Type I error and power, we propose four new criteria measuring the benefits and losses for individuals both inside and outside of the clinical trial. Compared with designs with equal randomization, the proposed design gives trial participants a better chance to receive their personalized optimal treatments and thus results in a higher response rate on the trial. This design increases the chance to discover a successful new drug by an adaptive enrichment strategy, i.e. identification and selective enrollment of a subset of patients who are sensitive to the experimental therapies. Simulation studies demonstrate these advantages of the proposed design. It is illustrated by an example based on an actual clinical trial in non-small-cell lung cancer.  相似文献   
948.
Heterogeneity is an enormously complex problem because there are so many dimensions and variables that can be considered when assessing which ones may influence an efficacy or safety outcome for an individual patient. This is difficult in randomized controlled trials and even more so in observational settings. An alternative approach is presented in which the individual patient becomes the “subgroup,” and similar patients are identified in the clinical trial database or electronic medical record that can be used to predict how that individual patient may respond to treatment.  相似文献   
949.
Customers are averse to disappointment that arises when economic outcomes fall short of expectations. In this study, we study a two‐period model in which the firm may create rationing in either period. In the anticipation of possible disappointment due to stock‐outs, strategic customers decide when to purchase and the firm determines the prices and rationing levels in each period. We explore the impact of disappointment aversion on customers' strategic purchasing behavior and the firm's pricing and rationing decisions. Without disappointment aversion, it is optimal for the firm to adopt a uniform pricing policy without rationing. However, when strategic customers are averse to disappointment, a firm may be able to increase profits with an appropriate level of rationing. We analyze both the mark‐up and mark‐down policies. We show that, in a mark‐down scenario, the firm always benefits from disappointment aversion behavior by using an appropriate level of rationing in a low‐price period. However, in a mark‐up scenario, whether it is beneficial for the firm to induce disappointment aversion behavior depends on how customers frame payoffs in different periods when forming utilities. Particularly, when customers compartmentalize payoffs in different periods to form utilities, the firm should not induce disappointment aversion behavior.  相似文献   
950.
We show that the length of compulsory education has a causal impact on regional labor mobility. We reach this conclusion from an analysis of a quasi‐exogenous staged Norwegian school reform, using register data on the whole population. Based on the results, we conclude that part of the US–Europe difference, as well as the European North–South difference in labor mobility, is likely to be due to differences in levels of education in the respective regions.  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