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   586篇
  免费   5篇
电工技术   6篇
化学工业   57篇
金属工艺   11篇
机械仪表   5篇
建筑科学   22篇
矿业工程   9篇
能源动力   25篇
轻工业   40篇
水利工程   5篇
石油天然气   3篇
无线电   26篇
一般工业技术   38篇
冶金工业   256篇
原子能技术   9篇
自动化技术   79篇
  2021年   4篇
  2019年   3篇
  2018年   5篇
  2017年   4篇
  2016年   5篇
  2015年   8篇
  2014年   10篇
  2013年   37篇
  2012年   14篇
  2011年   23篇
  2010年   12篇
  2009年   11篇
  2008年   23篇
  2007年   23篇
  2006年   32篇
  2005年   19篇
  2004年   23篇
  2003年   7篇
  2002年   13篇
  2001年   13篇
  2000年   15篇
  1999年   19篇
  1998年   16篇
  1997年   14篇
  1996年   14篇
  1995年   22篇
  1994年   17篇
  1993年   18篇
  1992年   18篇
  1991年   3篇
  1990年   18篇
  1989年   11篇
  1988年   6篇
  1987年   7篇
  1986年   11篇
  1985年   11篇
  1984年   10篇
  1983年   5篇
  1982年   11篇
  1981年   8篇
  1980年   9篇
  1977年   6篇
  1976年   3篇
  1975年   5篇
  1974年   5篇
  1973年   3篇
  1971年   2篇
  1969年   2篇
  1967年   2篇
  1966年   2篇
排序方式: 共有591条查询结果,搜索用时 140 毫秒
61.
Psychological research is increasingly involved in debates regarding abortion. While recognizing the diversity of ethical and moral issues intertwined with abortion, the American Psychological Association (APA) has focused its involvement on psychological factors, most recently by appointing an expert panel to review the literature on psychological effects. This article notes the history of APA involvement and reports on the panel's conclusions. It presents evidence that abortion is not likely to be followed by severe psychological responses and that psychological aspects can best be understood within a framework of normal stress and coping rather than a model of psychopathology. Correlates of more negative responses following abortion are also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
62.
The present study investigated developmental differences in the effects of repeated interviews and interviewer bias on children's memory and suggestibility. Three- and 5-year-olds were singly or repeatedly interviewed about a play event by a highly biased or control interviewer. Children interviewed once by the biased interviewer after a long delay made the most errors. Children interviewed repeatedly, regardless of interviewer bias, were more accurate and less likely to falsely claim that they played with a man. In free recall, among children questioned once after a long delay by the biased interviewer, 5-year-olds were more likely than were 3-year-olds to claim falsely that they played with a man. However, in response to direct questions, 3-year-olds were more easily manipulated into implying that they played with him. Findings suggest that interviewer bias is particularly problematic when children's memory has weakened. In contrast, repeated interviews that occur a short time after a to-be-remembered event do not necessarily increase children's errors, even when interviews include misleading questions and interviewer bias. Implications for developmental differences in memory and suggestibility are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
63.
64.
Unlike inhaled beta 2-agonists, more studies need to be performed before the action of systemic beta 2-agonists on athletic performance can be assessed accurately. Experiments in animals with oral clenbuterol have shown augmentation in muscle bulk across numerous species, but human studies cannot confirm similar muscle mass enlargement in healthy men. Although the human studies demonstrate the potential for long-acting systemic beta 2-agonists to increase muscle strength in certain muscle fiber types, it is difficult to judge the drugs' effects on overall athletic performance, because athletic skill is more than strength, speed, and endurance. The effect of oral clenbuterol on athletic performance cannot be evaluated from its actions on muscle strength alone. However, as evidence stands now, sports regulatory agencies are correct to ban systemic beta 2-agonists until the following 2 points can be proven: (1) oral forms provide a therapeutic benefit that cannot be obtained with aerosol or inhaled forms; and (2) oral forms do not give any unfair advantage to the competitor in muscle strength, power output, or endurance. Provided they are administered as prescribed, aerosol or inhaled beta-agonists do not impart an unfair advantage or enhance athletic performance and can continue to be used in competition by athletes with EIA.  相似文献   
65.
Describes agreement among diagnoses made according to 5 definitions of endogenous depression in a sample of 99 depressed elders and discusses the relationship among these systems and selected demographic and clinical characteristics. Poor to fair agreement was generally demonstrated, except for Research Diagnostic Criteria (R. Spitzer et al, 1978) and Diagnostic and Statistical Manual of Mental Disorders-III—Revised (DSM-III—R), which demonstrated excellent agreement. Mostly, demographic and clinical variables (e.g., severity of depression) were unrelated to endogeneity diagnoses. The conclusion was reached that these criteria are not all measuring the same construct in older adults and that the relationship between depression severity and endogeneity should be discussed in terms of specific definitions rather than in general terms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
66.
We review components of Public Law (PL) 99-457 and discuss several concerns related to the practice of psychology and early intervention. PL 99-457 establishes a new national blueprint for expanding the opportunities and benefits of early intervention and preschool services to children and families. We examined implications of the new law in terms of the following broad categories: assessment and diagnosis, intervention, planning and case management, program evaluation, and interagency collaboration. On the basis of practice needs in these areas, we propose several areas of needed training for child practitioners. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
67.
We report on a cross-sectional high resolution transmission electron microscope study of lead sulfide nanocrystal quantum dots (NCQDs) dispersed on electron-transparent silicon nanopillars that enables nearly atomically-resolved simultaneous imaging of the entire composite: the quantum dot, the interfacial region, and the silicon substrate. Considerable richness in the nanocrystal shape and orientation with respect to the substrate lattice is observed. The average NCQD-substrate separation is found to be significantly smaller than the length of the ligands on the NCQDs. Complementary photoluminescence measurements show that light emission from PbS NCQDs on silicon is effectively quenched which we attribute to intrinsic mechanisms of energy and charge transfer from PbS NCQDs to Si.  相似文献   
68.
69.
Generation of test benches for large DSP behavioral models is a complicated, labor intensive task. Also, tests generated manually satisfy no formal definition of completeness. To address these needs, high level approaches to test bench development are employed which relieve the modeler of the details of this task. High level design tools are used to develop the test bench VHDL code. The test bench code models sensors which drive the Model Under Test (MUT). Data files which can also drive the MUT are prepared by environmental data generators. The system specification values are linked to the testbench via requirements capture tools and test plans. Intelligent interfaces are used to control the development and simulation of the test bench. The approach is applicable to the testing of any DSP system modeled in the VHDL language. It provides the modeler with the capability to rapidly test DSP models and adjust the model test environment to frequent changes in system requirements.Material in this paper was previously presented at the 1 st Annual RASSP Conference, Arlington, Virginia, August 16, 1994, at the 2nd Annual RASSP Conference, Arlington, VA, July 1995, and at the Spring 1995 VHDL International Users Forum in San Diego, CA.  相似文献   
70.
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