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   2040篇
  免费   298篇
  国内免费   200篇
电工技术   179篇
综合类   305篇
化学工业   32篇
金属工艺   13篇
机械仪表   79篇
建筑科学   148篇
矿业工程   24篇
能源动力   17篇
轻工业   31篇
水利工程   25篇
石油天然气   21篇
武器工业   49篇
无线电   276篇
一般工业技术   103篇
冶金工业   180篇
原子能技术   3篇
自动化技术   1053篇
  2024年   6篇
  2023年   27篇
  2022年   57篇
  2021年   58篇
  2020年   69篇
  2019年   58篇
  2018年   60篇
  2017年   67篇
  2016年   70篇
  2015年   118篇
  2014年   166篇
  2013年   142篇
  2012年   180篇
  2011年   244篇
  2010年   168篇
  2009年   128篇
  2008年   164篇
  2007年   161篇
  2006年   124篇
  2005年   122篇
  2004年   84篇
  2003年   52篇
  2002年   33篇
  2001年   41篇
  2000年   23篇
  1999年   38篇
  1998年   9篇
  1997年   9篇
  1996年   5篇
  1995年   5篇
  1994年   3篇
  1993年   2篇
  1992年   4篇
  1990年   3篇
  1988年   4篇
  1987年   4篇
  1985年   3篇
  1983年   2篇
  1982年   4篇
  1968年   1篇
  1965年   2篇
  1964年   2篇
  1963年   1篇
  1962年   1篇
  1961年   1篇
  1958年   2篇
  1957年   1篇
  1956年   1篇
  1955年   2篇
  1954年   1篇
排序方式: 共有2538条查询结果,搜索用时 78 毫秒
1.
近年来,我国传统暴力犯罪与成年人犯罪呈下降态势,但是,犯罪案由层出不穷。为有效提升公安实践工作中犯罪预测能力,打击各类违法犯罪事件,本文针对犯罪数据,提出一种新型犯罪预测模型。利用密度聚类分析方法将犯罪数据分类,然后进行数据降维提取关键属性生成特征数据,继而对特征数据进行加权优化并采用机器学习的方式对特征数据进行学习,从而预测犯罪案由。实验结果表明,与传统方法相比,本文方法具有更好的预测效果,为公安实践工作中类似案件的侦破和预防,提供新的路径支撑。  相似文献   
2.
In its policy rationale for evidence-based practice in psychology (EBPP), the APA Presidential Task Force on Evidence-Based Practice (see record 2006-05893-001) claims to have constituted itself with "scientists and practitioners from a wide range of perspectives and traditions, reflecting the diverse perspectives within the field" (p. 273). We applaud this attention to diversity but contend that an entire perspective of the debate was omitted in the Task Force's newly approved policy and its underlying report. The failure to consider a philosophy of science perspective led the Task Force to make a number of epistemological assumptions that are not based on evidence or rationale and that thus violate the very spirit of evidence-based decision making. In this comment, we reveal a few of these assumptions and discuss their detrimental consequences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
3.
The authors explore the extent to which eating disorders, specifically anorexia nervosa (AN) and bulimia nervosa (BN), represent culture-bound syndromes and discuss implications for conceptualizing the role genes play in their etiology. The examination is divided into 3 sections: a quantitative meta-analysis of changes in incidence rates since the formal recognition of AN and BN, a qualitative summary of historical evidence of eating disorders before their formal recognition, and an evaluation of the presence of these disorders in non-Western cultures. Findings suggest that BN is a culture-bound syndrome and AN is not. Thus, heritability estimates for BN may show greater variability cross-culturally than heritability estimates for AN, and the genetic bases of these disorders may be associated with differential pathoplasticity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
4.
金属-橡胶硫化粘接过程中分子取向行为的间接证据   总被引:2,自引:1,他引:1  
对金属-橡胶热硫化粘接复合体的剥离行为进行了研究,同一粘接试样的双向180°剥离试验显示出了巨大的差异。本文分析了弹性材料在硫化过程中的分子行为,并提出了相应的新假设,认为这是由于金属-橡胶在硫化粘接过程中分子取向交联行为所致。这种双向180°剥离破坏现象可被看作是金属-橡胶硫化粘接过程中分子取向行为的间接证据。  相似文献   
5.
本文阐述了一种表示多源视觉传感信息的有效方法和一种基于Dempster-Shafer证据理论的多传感器信息融合技术。着重分析了移动机器人视觉传感器信息中存在的相关性及其解决方法,提出了相关函数、相关证据等概念,并针对证据之间存在的相关性给出了一种改进的综合函数。  相似文献   
6.
Causal learning requires integrating constraints provided by domain-specific theories with domain-general statistical learning. In order to investigate the interaction between these factors, the authors presented preschoolers with stories pitting their existing theories against statistical evidence. Each child heard 2 stories in which 2 candidate causes co-occurred with an effect. Evidence was presented in the form: AB→E; CA→E; AD→E; and so forth. In 1 story, all variables came from the same domain; in the other, the recurring candidate cause, A, came from a different domain (A was a psychological cause of a biological effect). After receiving this statistical evidence, children were asked to identify the cause of the effect on a new trial. Consistent with the predictions of a Bayesian model, all children were more likely to identify A as the cause within domains than across domains. Whereas 3.5-year-olds learned only from the within-domain evidence, 4- and 5-year-olds learned from the cross-domain evidence and were able to transfer their new expectations about psychosomatic causality to a novel task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
7.
对导线物证同一性的鉴定,可先用X射线能谱仪快速确定物证为同一物的必要条件,再用扫描电镜对物证的特征条纹或金相组织进行最后判定。该方法简便,可靠。  相似文献   
8.
This study presents results of a survey of self-proclaimed computer hackers about their perceptions in regards to illegal hacking. Results show that hackers continue to engage in illegal hacking activities despite the perception of severe judicial punishment. A closer look shows that hackers perceive a high utility value from hacking, little informal sanctions, and a low likelihood of punishment. These perceptions coupled with a high level of moral disengagement partially explain the hacker's illegal behavior.  相似文献   
9.
10.
A new combination rule based on Dezert-Smarandache theory (DSmT) is proposed to deal with the conflict evidence resulting from the non-exhaustivity of the discernment frame. A two-dimensional measure factor in Dempster-Shafer theory (DST) is extended to DSmT to judge the conflict degree between evidence. The original DSmT combination rule or new DSmT combination rule can be selected for fusion according to this degree. Finally, some examples in simultaneous fault diagnosis of motor rotor are given to illustrate the effectiveness of the proposed combination rule.  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