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   4092篇
  免费   132篇
  国内免费   44篇
管理学   355篇
劳动科学   2篇
民族学   36篇
人口学   39篇
丛书文集   402篇
理论方法论   150篇
综合类   2589篇
社会学   159篇
统计学   536篇
  2024年   15篇
  2023年   29篇
  2022年   35篇
  2021年   43篇
  2020年   63篇
  2019年   75篇
  2018年   79篇
  2017年   99篇
  2016年   105篇
  2015年   102篇
  2014年   184篇
  2013年   453篇
  2012年   252篇
  2011年   259篇
  2010年   202篇
  2009年   227篇
  2008年   228篇
  2007年   261篇
  2006年   242篇
  2005年   228篇
  2004年   191篇
  2003年   207篇
  2002年   179篇
  2001年   184篇
  2000年   113篇
  1999年   47篇
  1998年   26篇
  1997年   18篇
  1996年   22篇
  1995年   16篇
  1994年   19篇
  1993年   7篇
  1992年   11篇
  1991年   9篇
  1990年   7篇
  1989年   4篇
  1988年   8篇
  1987年   3篇
  1986年   2篇
  1985年   4篇
  1984年   1篇
  1983年   2篇
  1982年   2篇
  1977年   2篇
  1976年   1篇
  1975年   2篇
排序方式: 共有4268条查询结果,搜索用时 234 毫秒
71.
摘要:压力是气井和气藏生产动态分析的灵魂,很多动态分析方法都与压力有着直接的联系。然而,由于致密低渗透气藏产量低、压力下降快、关井压力恢复缓慢等生产特征,以及生产方式的限制,在生产过程中很难获得气井或气藏地层压力资料。压降法、产量不稳定分析法和产量递减曲线分析方法是气藏常用的气井生产动态分析方法,但由于地层压力资料缺乏,压降法和产量不稳定分析法也都受到了很大的限制,在衰减递减曲线分析方法的基础上对其进行修正,摆脱了压力资料的限制,通过和压降法对比分析,验证了修正衰减曲线分析方法在生产动态分析中的可靠性。  相似文献   
72.
Tactical production-distribution planning models have attracted a great deal of attention in the past decades. In these models, production and distribution decisions are considered simultaneously such that the combined plans are more advantageous than the plans resolved in a hierarchical planning process. We consider a two-stage production process, where in the first stage raw materials are transformed into continuous resources that feed the discrete production of end products in the second stage. Moreover, the setup times and costs of resources depend on the sequence in which they are processed in the first stage. The minimum scheduling unit is the product family which consists of products sharing common resources and manufacturing processes. Based on different mathematical modelling approaches to the production in the first stage, we develop a sequence-oriented formulation and a product-oriented formulation, and propose decomposition-based heuristics to solve this problem efficiently. By considering these dependencies arising in practical production processes, our model can be applied to various industrial cases, such as the beverage industry or the steel industry. Computation tests on instances from an industrial application are provided at the end of the paper.  相似文献   
73.
《Journal of homosexuality》2012,59(10):1274-1302
This study used a correlational design with a sample of university students to clarify the relationships between attitude functions and homonegativity with respect to gender. Classic work on attitude functions posits that attitudes serve psychological needs for the attitude holder. Herek (1986b) adapted this theory to explain attitudes toward homosexuality. Herek (1987) identified four functions: ego-defensive (defense of threats to the self), value-expressive (expression of key values), social-expressive (expression of important social norms), and experiential (based on past experiences). Results suggested that men were more likely to attribute their attitudes to the ego-defensive function. Men and women were equally likely to attribute their attitudes to the experiential function. The ego-defensive function was the best predictor of homonegativity for men and women, whether they held generally positive or generally negative attitudes toward homosexuality. The experiential function did not predict homonegativity. Participants tended to be neither very homonegative nor very ego-defensive.  相似文献   
74.
L'essor des chaînes d'approvisionnement mondiales (CAM) éloigne l'emploi de la demande, géographiquement et sectoriellement. Pour mieux comprendre le phénomène, les auteurs mesurent l'emploi lié aux CAM selon sa localisation et celle de la demande, en se fondant sur les données de la base WIOD et en complétant les estimations déjà présentées par le BIT. L'analyse porte sur la période 1995–2013 et sur 40 économies. Elle montre que la Chine, principale bénéficiaire de la demande liée aux CAM autrefois, contribue maintenant à l'alimenter, tout comme les relations de production entre économies émergentes. En outre, le poids des services liés à une demande manufacturière augmente.  相似文献   
75.
高含水期陆相复杂断块层状油藏剩余油分布复杂,油藏模拟难度大。马11复杂断块油藏在油藏精细描述基础上,利用动静态综合分析研究与密网格大规模数值模拟研究相结合,提高了剩余油研究精度和可信度;在此基础上,针对油藏剩余油分布特点并结合当前经济技术条件,部署实施了以调整井、调剖、堵水、油水井大修为主的剩余油挖潜方案,油藏含水上升率大幅度下降、采油速度上升、采收率提高了。  相似文献   
76.
Abstract

Purpose: This paper presents a combined multi-phase supplier selection model. The process repeatedly revisits the criteria and sourcing decision as the development process continues. This enables a structured adoption of product and production system innovation from strategic suppliers, where previously the literature purely focuses on product innovation or cost reduction. Design/methodology/approach: The authors adopted an embedded researcher style, inductive, qualitative case study of an industrial supply cluster comprising a focal automotive company and its interaction with three different strategic stamping suppliers. Findings: Our contribution is the multi-phased production and product innovation process. This is an advance from traditional supplier selection and also an extension of ideas of supplier-located product development as it includes production system development, and complements the literature on working with strategic suppliers. Specifically, we explicitly articulate the previously unreported issue of whether a supplier chosen for its innovation capabilities at the start of the new product development process will also be the most appropriate supplier during the production system development phase, when an ability to work collaboratively may be the most important attribute, or in the large-scale production phase when an ability to manufacture at low unit cost may be most important. Originality/value: The paper identifies a multi-phase approach to tendering within a fixed body of strategic suppliers which seeks to identify the optimum technological and process decisions as well as the traditional supplier sourcing choice. These areas have not been combined before and generate a valuable approach for firms to adopt as well as for researchers to extend our understanding of a highly complex process.  相似文献   
77.
制造业是我国国民经济的支柱产业,但也是环境污染物排放的主要来源、能源消耗主体和温室气体排放大户。制造系统高能耗、高物耗、高碳排放的加工过程是造成制造业碳排放量大的重要原因。生产单元作为制造系统的加工的主体,其碳排放量的核算是确定整个制造系统乃至制造业碳排放总量的关键。本文首先对生产单元的原材料、电能、辅助物料及废屑处理所引起的碳排放进行分析,确定生产单元的碳排放源;其次,产品合格率的不同会造成生产单元输入及输出的成品/半成品数量的差异,进而影响生产单元单位产品的碳排放量,在此基础上,综合考虑了原材料、电能、辅助物料及废屑处理的碳排放情况,构建了给定工艺流程下生产单元碳排放核算模型。最后,结合一汽车排气装置加工实例,分别核算加工过程中九个生产单元的碳排放量,验证了模型的可行性。  相似文献   
78.
土地流转是实现规模化经营的前提之一,然而土地流转中却出现大量小农复制,从而影响土地流转的质量和效果。运用12省(自治区)2 553份农户问卷,详细分析土地流转中小农复制的现状及其形成原因。研究发现:(1)农户流转耕地面积不大,转入户流转面积20亩及以下的约占总转入户数的60.3%,转出户流转面积5亩及以下的约占总转出户数的74.38%,转出户中仍然经营土地的约占总转出户数的74%。(2)农业分工发达使生产更加方便、文化传统形成路径依赖、禀赋效应产生“价值幻觉”以及公共服务不健全使未来存在不确定性导致转出户流转部分土地。乡土社会限制土地流转范围和经营风险增加风险感知导致转入户流转小规模土地。  相似文献   
79.
现实的人是马克思新哲学的出发点和落脚点,同时也是马克思对整个思想史上各种“片面人”的颠覆性阐释,是唯物史观与唯心史观和经验论决裂的标识。它不同于性恶论或性善论或既无善亦无恶论,也不同于黑格尔的“绝对精神”的人,更不同于费尔巴哈的“类”。与黑格尔思想及其青年黑格尔派和费尔巴哈等人思想交锋的过程中,马克思分别通过以所有制为轴线动态考察历史发展和以分工为轴线静态考察社会的结构性存在两条线索来阐释“现实的人”的内涵,并以生产工具为红线,对资本主义社会下“现实的人”的静态结构和动态发展予以微观透视。由此,按照唯物史观的基本立场、观点和方法来说,以经济决定政治、政治决定文化的序列构成的结构性存在来解释人才是马克思所谓的“现实的人”。  相似文献   
80.
The purpose of this study was to provide a more comprehensive understanding of the relation between early parent‐child interactions and subsequent behavior problems and how certain cognitive processes mediate this relation. Specifically, this study investigated whether attention, inhibition, and planning skills mediate the relation between attachment security and behavior problems. Data were collected as part of the National Institute of Child Health and Development‐Study of Early Child Care and Youth Development when children (N = 1004) were between 36 months and the third grade. Results from structural equation models indicated that sustained attention mediated the relation between disorganized attachment and social problems. Planning mediated the relation between disorganized attachment and subsequent thought problems, attention problems, and delinquent behavior. Avoidant, ambivalent, and disorganized attachment directly predicted several behavior problems. Implications for theory and future research are discussed.  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