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   2612篇
  免费   649篇
  国内免费   55篇
电工技术   13篇
综合类   210篇
化学工业   46篇
金属工艺   24篇
机械仪表   11篇
建筑科学   777篇
矿业工程   632篇
能源动力   47篇
轻工业   87篇
水利工程   46篇
石油天然气   266篇
无线电   17篇
一般工业技术   66篇
冶金工业   897篇
原子能技术   29篇
自动化技术   148篇
  2024年   24篇
  2023年   52篇
  2022年   88篇
  2021年   120篇
  2020年   244篇
  2019年   107篇
  2018年   98篇
  2017年   128篇
  2016年   163篇
  2015年   127篇
  2014年   194篇
  2013年   195篇
  2012年   176篇
  2011年   189篇
  2010年   168篇
  2009年   132篇
  2008年   125篇
  2007年   139篇
  2006年   100篇
  2005年   97篇
  2004年   96篇
  2003年   77篇
  2002年   65篇
  2001年   61篇
  2000年   54篇
  1999年   65篇
  1998年   26篇
  1997年   28篇
  1996年   23篇
  1995年   22篇
  1994年   30篇
  1993年   13篇
  1992年   17篇
  1991年   7篇
  1990年   8篇
  1989年   10篇
  1988年   8篇
  1987年   7篇
  1986年   4篇
  1985年   6篇
  1984年   4篇
  1980年   3篇
  1970年   1篇
  1964年   3篇
  1963年   1篇
  1961年   2篇
  1959年   1篇
  1957年   1篇
  1956年   1篇
  1955年   2篇
排序方式: 共有3316条查询结果,搜索用时 16 毫秒
21.
商业性矿产勘查的理论与实践   总被引:1,自引:0,他引:1  
商业性矿产勘查是一种按照经济属性划分的地质工作,是企业的生产经营活动。商业性矿产勘查的经营成果是具有经济开采价值的地质储量,要通过转出矿业权或转入矿产品生产实现勘查投资的回收和盈利。其运行方式与传统计划管理体制下的矿产勘查有多种差异。云南地矿资源股份有限公司商业性矿产勘查的运行给了有益的启示。  相似文献   
22.
This paper presents the area and water allocation model (AWAM), which incorporates deficit irrigation for optimizing the use of water for irrigation. This model was developed for surface irrigation schemes in semiarid regions under rotational water supply. It allocates the land area and water optimally to the different crops grown in different types of soils up to the tertiary level or allocation unit. The model has four phases. In the first phase, all the possible irrigation strategies are generated for each crop-soil-region combination. The second phase prepares the irrigation program for each strategy, taking into account the response of the crop to the water deficit. The third phase selects the optimal and efficient irrigation programs. In the fourth phase of the model, irrigation programs are modified by incorporating the conveyance and the distribution efficiencies. These irrigation programs are then used for allocating the land and water resources and preparing the water release schedule for the canal network.  相似文献   
23.
This book is the result of months of work by a small group interested in ethical debates surrounding diverse professional practices. The different chapters examine the relationships among ethics, morality, and psychology. Of special interest are ethical questions relating to the conduct of research; the use and interpretation of standardized tests, given issues of validity and reliability; and the problems of developing and transmitting expertise in psychological practice. The values of respect, liberty, and justice are seen as relevant and applicable to psychological practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
24.
This study explored the moderating effects of children's neighborhoods on the link between hostile parenting and externalizing behavior. Participants were 1st- or 2nd-grade children in an urban northeastern community. Children were administered the Parenting and Neighborhood scales of the Child Puppet Interview, and mothers completed questionnaires on neighborhood quality and parenting practices. Census tract measures of neighborhood quality and teachers' reports of children's externalizing behavior also were obtained. Results indicated that children's and mothers' perceptions of neighborhood involvement-cohesion buffered the link between hostile parenting and externalizing problems. Children's externalizing behavior was unrelated to census tract variables. Findings highlight the protective effect of neighborhood social cohesion and the utility of including young children's perspectives in research on neighborhoods and families. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
25.
To keep consulting psychologists up-to-date on research relevant to practice, a review was conducted of the recent literature written about individual assessment practices. This review on articles and books that were published in the past 10 years. Trends in individual assessment practices are discussed, and theoretical support for the use of individual assessment in personnel selection is provided despite the limited empirical support. A research agenda for individual assessment practices is also proposed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
26.
Previous research on organizational practices is replete with contradictory evidence regarding their effects. Here, the authors argue that these contradictory findings may have occurred because researchers have often examined complex practice combinations and have failed to investigate a broad variety of firm-level outcomes. Thus, past research may obscure important differential effects of specific practices on specific firm-level outcomes. Extending this research, the authors develop hypotheses about the effects of practices that (a) enable information sharing, (b) set boundaries, and (c) enable teams on 3 different firm-level outcomes: financial performance, customer service, and quality. Relationships are tested in a sample of observations from over 200 Fortune 1000 firms. Results indicate that information-sharing practices were positively related to financial performance 1 year following implementation of the practices, boundary-setting practices were positively related to firm-level customer service, and team-enabling practices were related to firm-level quality. No single set of practices predicted all 3 firm-level outcomes, indicating practice-specific effects. These findings help resolve the theoretical tension in the literature regarding the effects of organizational practices and offer guidance as to how to best target practices to increase specific work-related outcomes. Implications for theory, research, and practice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
27.
排山楼金矿位于华北地台北缘,为受控于韧性剪切带的大型金矿床。该矿床成因与韧性剪切带密切相关,矿区成矿地质条件优越,具有很好的找矿潜力。通过总结排山楼金矿地质特征及其主要控矿因素,认为区内韧性剪切带为控岩(控矿)构造,控制着赋矿糜棱岩和金矿体的空间展布,向矿区深部赋矿岩石变薄,找矿空间变小。通过分析T4矿体的品位和厚度分布规律发现,矿体厚度及品位分布规律在空间上表现出高度一致性,根据金品位等值线图判断矿体向南西侧伏。研究认为T4矿体在南西深部其厚度及品位降低趋势明显,向深部工业价值不大,应重点加强对其他韧性剪切带找矿潜力的研究。  相似文献   
28.
Hope is recognized as one of four key factors contributing to psychotherapeutic change across a variety theoretical approaches (Hubble, Duncan, & Miller, 1999), especially early in the psychotherapeutic sequence. To date little research has looked at how hope is translated into specific practices by psychotherapists during psychotherapy sessions. This case study employed basic interpretive inquiry (Merriam, 1998) to explore the hope-focused practices of five hope-educated psychotherapists with 11 clients early in the therapy sequence. Two categories characterize the overall findings, that is, implicit and explicit hope-focused practices. This first paper in a two-part research report focuses on implicit hope-focused interventions. Implicit hope-focused interventions were those practices identified by therapists as addressing client hope without employing the word hope explicitly. Implicit hope practices addressed two key aspects of therapy, (a) attending to therapeutic relationship, and (b) fostering client perspective change. The second paper in this series examines findings regarding explicit hope-focused interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
29.
竹筒尖铀矿床位于下庄矿田西北部,矿床外围黄竹地段铀成矿条件较好,区内F1、F2、F4断裂与竹筒尖矿床F3号组带具有相似的构造特征,铀矿化较好;“地面伽玛能谱测量+土壤氡浓度测量+分量化探”综合找矿方法应用取得较好效果,可见区内能谱铀、土壤氡浓度及分量铀的异常面积大且复合程度高;合水口靶区具有较好找矿线索。  相似文献   
30.
曹梁 《世界有色金属》2020,(1):68-68,70
各种工程项目的数量和规模的不断增加,进一步加大了社会对矿产的需求量。基于此种情况,本文对深部地质勘查和钻探找矿技术进行研究。通过实际的工程案例对该技术进行分析,希望可以对深部找矿工作提供一定的帮助。  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