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   53970篇
  免费   4598篇
  国内免费   3116篇
电工技术   3449篇
技术理论   6篇
综合类   6197篇
化学工业   4952篇
金属工艺   1711篇
机械仪表   2597篇
建筑科学   6594篇
矿业工程   2383篇
能源动力   1298篇
轻工业   3183篇
水利工程   2046篇
石油天然气   2612篇
武器工业   353篇
无线电   4130篇
一般工业技术   3981篇
冶金工业   2826篇
原子能技术   422篇
自动化技术   12944篇
  2024年   131篇
  2023年   618篇
  2022年   873篇
  2021年   1317篇
  2020年   1190篇
  2019年   1134篇
  2018年   977篇
  2017年   1184篇
  2016年   1436篇
  2015年   1646篇
  2014年   2781篇
  2013年   2738篇
  2012年   3305篇
  2011年   3654篇
  2010年   2903篇
  2009年   3227篇
  2008年   3137篇
  2007年   3897篇
  2006年   3656篇
  2005年   3326篇
  2004年   2805篇
  2003年   2572篇
  2002年   2169篇
  2001年   1851篇
  2000年   1570篇
  1999年   1284篇
  1998年   977篇
  1997年   870篇
  1996年   758篇
  1995年   681篇
  1994年   575篇
  1993年   461篇
  1992年   367篇
  1991年   264篇
  1990年   228篇
  1989年   207篇
  1988年   165篇
  1987年   122篇
  1986年   86篇
  1985年   84篇
  1984年   60篇
  1983年   51篇
  1982年   34篇
  1981年   41篇
  1980年   34篇
  1979年   38篇
  1978年   20篇
  1976年   19篇
  1975年   22篇
  1974年   20篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
131.
罗钢  陈俊亮 《计算机学报》1991,14(11):838-844
Prolog逻辑程序设计语言具有不同于传统程序设计语言的特点.本文根据测试Prolog程序的实践,提出了一系列为Prolog程序生成测试用例的准则.按这些准则测试实际程序效果良好.这是在逻辑程序测试新领域迈出的一步.  相似文献   
132.
This paper presents a mechanism which infers a user's plans from his/her utterances by directing the inference process towards the more likely interpretations of a speaker's statements among many possible interpretations. Our mechanism uses Bayesian theory of probability to assess the likelihood of an interpretation, and it complements this assessment by taking into consideration two aspects of an interpretation: its coherence and its information content. The coherence of an interpretation is determined by the relationships between the different statements in the discourse. The information content of an interpretation is a measure of how well defined the interpretation is in terms of the actions to be performed on the basis of this interpretation. This measure is used to guide the inference process towards interpretations with higher information content. The information content of an interpretation depends on the specificity and the certainty of the inferences in it, where the certainty of an inference depends on the knowledge on which the inference is based. Our mechanism has been developed for use in task-oriented consultation systems. The particular domain that we have chosen for exploration is that of travel booking.  相似文献   
133.
This paper discusses the feasibility of using neural networks as a tool in the fault detection process. A neural network is integrated with a state language programmable logic controller, an important device in an automatic control system. Time series data related to time spent in a state is gathered and used as input into a neural network, for the purpose of identifying when a fault has occurred. A feedforward neural network is used to identify which (if any) of three types of faults may have occurred. Experimental results related to sensitivity and accuracy measures are presented. A brief review of related applications and research is also presented.  相似文献   
134.
在各糖厂现用连续离心机原有生产实践基础上,对其机械吸震、加温、布温、机索结构、物料密封、机座等部件做了进一步改进,并取得可观的实效。  相似文献   
135.
We present our machine learning system, that uses inductive logic programming techniques to learn how to identify transmembrane domains from amino acid sequences. Our system facilitates the use of operators such as ‘contains’, that act on entire sequences, rather than on individual elements of a sequence. The prediction accuracy of our new system is around 93%, and this compares favourably with earlier results. This work was carried out with the support of a research grant from ISIS, Fujitsu Laboratories.  相似文献   
136.
A new comprehensive framework for narrative understanding has been developed. Its centerpiece is a new situational logic calledEpisodic Logic (EL), a knowledge and semantic representation well-adapted to the interpretive and inferential needs of general NLU. The most distinctive features of EL is its natural language-like expressiveness. It allows for generalized quantifiers, lambda abstraction, sentence and predicate modifiers, sentence and predicate reification, intensional predicates (corresponding to wanting, believing, making, etc.), unreliable generalizations, and perhaps most importantly, explicit situational variables (denoting episodes, events, states of affairs, etc.) linked to arbitrary formulas that describe them. These allow episodes to be explicitly related in terms of part-whole, temporal and causal relations. Episodic logical form is easily computed from surface syntax and lends itself to effective inference.  相似文献   
137.
开关DC—DC变换器并联运行问题的研究   总被引:4,自引:0,他引:4  
开关直流电源并联运行在许多场合应用。每一路电源输出阻抗的不一致性使每一路输出电流难以均衡,影响了系统的可靠性。本文提出了一种双回路DC—DC变换器的控制方案。由于采用电压环(外环)和电流环(内环)两环结构的双回路控制模式,变换器输出电流得到了有效控制,便于多个DC—DC变换器输出直接并联,从而实现了模块化,具有一定的实用性  相似文献   
138.
Counting Objects   总被引:1,自引:0,他引:1  
  相似文献   
139.
An attempt is made to elucidate the electrochemical aspects of the electroosmotic dewatering (EOD) of clays as reported in some recent work, especially that on interrupted DC power electroosmotic dewatering published by Rabie, Mujumdar and Weber (2). These authors showed that the dewatering by EOD stops after the DC power has been on for several minutes or hours; on interruption of their power and on short-circuiting of the electrodes, conditions can be created again for some further dewatering by DC power EOD. This discovery, of Rabie et al. is interpreted as a fuel cell effect and it is shown that it affords clues to several other electrochemical strategies for the possible enhancement of the efficiency of the EOD by DC power.

Further, the open circuit potentials observed by Rabie et al. (2) on the interruption of DC power are given an electrochemical interpretation which leads to quantitative estimates in agreement with the experimental values.  相似文献   
140.
油砂地层中子-伽玛能谱Monte-Carlo模拟   总被引:2,自引:0,他引:2  
本工作应用自行研制开发的中子 伽玛能谱测井的中子 伽玛射线随空间、能量、时间分布的蒙特卡罗模拟软件包计算了裸眼井、井眼里无下井仪器、油饱和砂岩地层、井眼注油条件下沿井轴和井壁的中子 伽玛射线随能量、时间分布及沿井轴和沿井壁的中子 伽玛射线能谱 ,研究了源距对中子 伽玛射线随能量、时间分布以及井轴与井壁中子 伽玛射线能谱的影响。  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