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961.
AbstractThere are n cards serially numbered from 1 to n. The cards are shuffled and placed in a line one after the other on top of a table with faces up. The numbers on the faces are read from left to right. If there are consecutive numbers in increasing order of magnitude the corresponding cards are merged into one. After the merger, the cards are numbered serially from one to whatever the number of cards we now have. The cards are shuffled and placed in a line one after another on top of the table with faces up. The process continues until we have only one card left. In this paper, we develop a probabilistic recurrence relation approach to obtain the mean, variance, and distribution of the number of shuffles needed. A Markov chain formulation and its properties are discussed in the paper as well. 相似文献
962.
An expectation-maximum (EM) likelihood algorithm is used to estimate two seemingly unrelated Tobit regressions in which the dependent variables are truncated normal. An illustrative example on the determination of the life-health insurance and pension benefits is also given. 相似文献
963.
Abstract This study examines the role of perceived self‐efficacy in mediating relations between mothers’ parenting behavior and variables such as maternal employment status, depressive symptoms, parenting stress, and child behavior problems. Subjects were 93 employed and 95 nonemployed, single, black mothers of a 3–5‐year‐old child who were current and former welfare recipients. Using linear structural relations modeling (LISREL), the findings support a model whereby (a) the more behavior problems the child is perceived to have, the more depressive symptoms the mother feels; (b) the more depressive symptoms the mother feels, the more likely she is to rate herself high in parenting stress; (c) the more depressive symptoms and parenting stress the mother experiences, the lower is the mother's estimate of her self‐efficacy; and (d) the lower the mother's self‐efficacy, the less competent is her parenting. The findings for employment status are similar; i.e., maternal employment predicted a trajectory leading to somewhat better parenting. In addition, child behavior problems were associated with less competent parenting both directly and indirectly through their effect on parenting stress and self‐efficacy. These results suggest that self‐efficacy has import as a mediator of the relations between maternal parenting and other psychosocial variables. There is no evidence, based on these findings, that employment in the low‐wage market is harmful either for single black mothers or their preschool children. However, job availability and an increase in the minimum wage are important policy considerations. 相似文献
964.
近十年来,我国创业成功的大学生中,有四成以上选择了与IT密切相关的行业。为了解我国西部地区大学生网络创业软硬件环境及相关状况,课题组专门设计制作问卷,历时半年,主要针对西部六个代表性城市的31所大学中各种学历层次的大学生,共计发出了21683份纸质问卷,用充分的数据详细展示了目前我国西部地区大学生的网络使用状况,对于网络创业的认知态度和相关创业知识获取的渠道,现实难题和困境等问题,并在数据的基础上做出客观剖析评价,为相关网络创业教育和经济支持政策的制定提供了现实依据。 相似文献
965.
高层次人才是稀缺资源,一个袁隆平带来了中国杂交稻产业的兴盛,一个比尔·盖茨创建了微软"帝国".人才重在使用,人才用起来是金子,不用变沙子.每个单位都应该认真检查和反省是否有压制和浪费人才的现象. 相似文献
966.
改革开放以来,我国政府改革先后经历了"泛政治化"和"去政治化"两个阶段,前者罔顾国情,以西方国家治理体系为典范,后者回避矛盾,追求纯行政范畴的改革,其共同特点都是脱离了政治-行政统一体这一制度情境。目前中国政府改革目前再次走到了需要在政治改革上有所作为的时间节点上,但不是简单回归上世纪80年代的政治改革,而是要以大部制改革为契机,并基于政治-行政统一体这一制度情境去探索国家治理结构的重新建构。 相似文献
967.
We propose an innovative time-varying collision risk (TCR) measurement for ship collision prevention in this article. The proposed measurement considers the level of danger of the approaching ships and the capability of a ship to prevent collisions. We define the TCR as the probability of the overlap of ships’ positions in the future, given the uncertainty of maneuvers. Two sets are identified: (1) the velocity obstacle set as the maneuvers of the own ship that lead to collisions with target ships, and (2) the reachable velocity set as the maneuvers that the own ship can reach regarding its maneuverability. We then measure the TCR as the time-dependent percentage of overlap between these two sets. Several scenarios are presented to illustrate how the proposed measurement identifies the time-varying risk levels, and how the approach can be used as an intuitively understandable tool for collision avoidance. 相似文献
968.
Rui Liu Yun Chen Jianping Wu Lei Gao Damian Barrett Tingbao Xu Xiaojuan Li Linyi Li Chang Huang Jia Yu 《Risk analysis》2017,37(4):756-773
Regional flood risk caused by intensive rainfall under extreme climate conditions has increasingly attracted global attention. Mapping and evaluation of flood hazard are vital parts in flood risk assessment. This study develops an integrated framework for estimating spatial likelihood of flood hazard by coupling weighted naïve Bayes (WNB), geographic information system, and remote sensing. The north part of Fitzroy River Basin in Queensland, Australia, was selected as a case study site. The environmental indices, including extreme rainfall, evapotranspiration, net‐water index, soil water retention, elevation, slope, drainage proximity, and density, were generated from spatial data representing climate, soil, vegetation, hydrology, and topography. These indices were weighted using the statistics‐based entropy method. The weighted indices were input into the WNB‐based model to delineate a regional flood risk map that indicates the likelihood of flood occurrence. The resultant map was validated by the maximum inundation extent extracted from moderate resolution imaging spectroradiometer (MODIS) imagery. The evaluation results, including mapping and evaluation of the distribution of flood hazard, are helpful in guiding flood inundation disaster responses for the region. The novel approach presented consists of weighted grid data, image‐based sampling and validation, cell‐by‐cell probability inferring and spatial mapping. It is superior to an existing spatial naive Bayes (NB) method for regional flood hazard assessment. It can also be extended to other likelihood‐related environmental hazard studies. 相似文献
969.
文章基于2000-2013年我国省级面板数据,构建引入城镇化增长与人口就业增长交互项和老龄化增长与人口就业增长交互项的动态面板模型,以全国人均GDP增长率为标准将我国划分为高速增长和中高速增长两类地区,采用SYS-GMM计量方法对人口就业视角下城镇化与老龄化在全国及两类地区对经济增长的影响作用进行实证分析.研究结果表明,对全国层面而言,城镇化通过影响人口就业对经济增长产生正向拉动作用,老龄化则通过影响人口就业对经济增长产生负向阻滞作用;两类地区中,城镇化拉动经济增长的效应在中高速地区更为明显,同时该地区相应的老龄化阻滞经济增长的影响也更为严重,远高于全国地区平均水平,但在高速增长地区老龄化的阻滞作用却并不显著. 相似文献
970.
作为天赋异禀的特殊群体,天才儿童早在汉代之前就已经出现;不过真正引起广泛的重视,则是迟至儒教确立的两汉之际才发生的。随着儒家童蒙教育趋于制度化,天才儿童们成为儒家思想的有力宣传者,以孝悌和笃学为中心的儒家品德,构成这些儿童事迹的主要内容,同时也进一步固定为后世的基本评价标准,长期以来儿童们需要依靠这些标准来确定自身的价值与声誉。天才儿童曲折地反映出时代的种种变化,从而构成了现实世界的某种镜像。其中最为引人注目的因素是儒教的影响。在儒教意识形态化的过程中,伴随着家族与社会的濡染,天才儿童成为现实儒家品行的载体。通过分析这些儿童形象的变迁与内涵,有助于更深刻地理解汉代儒家社会中童蒙教育的性质。 相似文献