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   19764篇
  免费   1919篇
  国内免费   1223篇
电工技术   881篇
综合类   2703篇
化学工业   1209篇
金属工艺   1188篇
机械仪表   793篇
建筑科学   1204篇
矿业工程   240篇
能源动力   128篇
轻工业   319篇
水利工程   182篇
石油天然气   329篇
武器工业   259篇
无线电   2464篇
一般工业技术   1802篇
冶金工业   3519篇
原子能技术   76篇
自动化技术   5610篇
  2024年   111篇
  2023年   359篇
  2022年   597篇
  2021年   729篇
  2020年   630篇
  2019年   421篇
  2018年   342篇
  2017年   463篇
  2016年   538篇
  2015年   623篇
  2014年   1199篇
  2013年   1106篇
  2012年   1323篇
  2011年   1766篇
  2010年   1398篇
  2009年   1344篇
  2008年   1219篇
  2007年   1231篇
  2006年   1131篇
  2005年   1060篇
  2004年   921篇
  2003年   770篇
  2002年   705篇
  2001年   521篇
  2000年   337篇
  1999年   285篇
  1998年   213篇
  1997年   214篇
  1996年   176篇
  1995年   158篇
  1994年   128篇
  1993年   106篇
  1992年   87篇
  1991年   45篇
  1990年   62篇
  1989年   57篇
  1988年   55篇
  1987年   21篇
  1986年   27篇
  1985年   24篇
  1984年   25篇
  1983年   17篇
  1966年   23篇
  1961年   16篇
  1959年   23篇
  1958年   20篇
  1957年   24篇
  1956年   17篇
  1955年   23篇
  1954年   17篇
排序方式: 共有10000条查询结果,搜索用时 968 毫秒
91.
Performance on antisaccade trials requires the inhibition of a prepotent response (i.e., don't look at the flashing cue) and the generation and execution of a correct saccade in the opposite direction. The authors attempted to further specify the role of working memory (WM) span differences in the antisaccade task. They tested high- and low-span individuals on variants of prosaccade and antisaccade trials in which an eye movement is the sole requirement. In 3 experiments, they demonstrated the importance of WM span differences in both suppression of a reflexive saccade and generation of a volitional eye movement. The results support the contention that individual differences in WM span are not exclusively due to differences in inhibition but also reflect differences in directing the focus of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
92.
基于约束优化的联想记忆模型学习算法   总被引:1,自引:1,他引:0  
汪涛  俞瑞钊 《通信学报》1992,13(5):88-92
本文提出了一种对称互连神经元网络的学习策略,利用全局约束优化方法确定连接权。优化过程采用了梯度下降技术。这种学习算法可以保证训练样本成为系统的稳定吸引子,并且具有优化意义上的最大吸引域。本文讨论了网络的存储容量,训练样本的渐近稳定性和吸引域大小。计算机实验结果说明了学习算法的优越性。  相似文献   
93.
Generation enhances item memory but may not enhance other aspects of memory. In 12 experiments, the author investigated the effect of generation on context memory, motivated in part by the hypothesis that generation produces a trade-off in encoding item and contextual information. Participants generated some study words (e.g., hot-___) and read others (e.g., hot-cold). Generation consistently enhanced item memory but did not enhance context memory. More specifically, generation disrupted context memory for the color of the target word but did not affect context memory for location, background color, and cue-word color. The specificity of the negative generation effect in context memory argues against a general item-context trade-off. A processing account of generation meets greater success. In addition, the results provide no evidence that generation enhances recollection of contextual details. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
94.
NiTi形状记忆合金基本驱动特性   总被引:2,自引:0,他引:2  
研究了预应变NiTi形状记忆合金的基本驱动特性,结果表明,加热和冷却过程回复力存在滞后行为;卸载过程中应力与应变具有与加热、冷却过程相关的非线性关系;卸尖力随卸载应变速率增加而降低,此外研究了预应变NiTi合金丝产生回复力后对外应力的响应行为。  相似文献   
95.
EuLisp has an integrated object system with reflective capabilities. We discuss some example applications which use these facilities to experiment with some advanced and powerful concepts, namely, finalization, virtual shared memory and persistence. A secondary goal is to attempt to illustrate the additional possibilities of metaobject programming over non-metalevel techniques.  相似文献   
96.
较详细地介绍了在北京核电厂模拟培训中心的模拟器上建立RMS仿真系统的工作。首先对仿真的原型进行分析和简化,建立数学物理模型,并对包括RCS、PZR、SG、CVCS等的近20个核电厂系统进行了动态仿真建模,确定RMS各监测点放射性水平仿真读数的计算方法,最后,给出部分仿真实验结果,以验证数学物理模型的可靠性和适用性。  相似文献   
97.
Determining contributions of source-monitoring and inhibitory function to age-related forgetting has been an elusive goal for cognitive theorists. Five studies used a verbal working memory paradigm to examine mechanisms accounting for disproportionate retroactive interference (RI) experienced with adult aging. Participants distinguished studied target-word pairs from interfering pairs that were read aloud. Source-monitoring and inhibitory task components varied through manipulations of response requirements. RI effects were primarily due to source-monitoring failures rather than to inhibitory failures. Removing both source and inhibitory components eliminated age differences in RI. When source monitoring was emphasized, RI continued to be observed in all age groups but disproportionately for older adults. Process dissociation analyses of memory found recollection decreases and familiarity increases consistent with source failures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
98.
99.
The authors examined whether participants can shift their criterion for recognition decisions in response to the probability that an item was previously studied. Participants in 3 experiments were given recognition tests in which the probability that an item was studied was correlated with its location during the test. Results from all 3 experiments indicated that participants' response criteria were sensitive to the probability that an item was previously studied and that shifts in criterion were robust. In addition, awareness of the bases for criterion shifts and feedback on performance were key factors contributing to the observed shifts in decision criteria. These data suggest that decision processes can operate in a dynamic fashion, shifting from item to item. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
100.
在天然河道中,河势演变虽具有一定的随机性,但仍有一定的规律可循,在一个河段内,一般可归纳出2-3条基本流路,为控制河势变化,需要选择出一条基本流路进行河道整治,当连续发生枯水期或洪水期时,部分河段的河势可能出现大的变化,为防止不利河势向下游传播,可修建较长的龙头弯道工程,利用龙头弯道工程分段调整,控导河势,保持河势稳定。  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