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   18462篇
  免费   289篇
  国内免费   17篇
电工技术   241篇
综合类   9篇
化学工业   3604篇
金属工艺   280篇
机械仪表   310篇
建筑科学   1108篇
矿业工程   109篇
能源动力   515篇
轻工业   1392篇
水利工程   177篇
石油天然气   225篇
武器工业   1篇
无线电   1101篇
一般工业技术   2907篇
冶金工业   4177篇
原子能技术   163篇
自动化技术   2449篇
  2022年   145篇
  2021年   238篇
  2020年   211篇
  2019年   255篇
  2018年   272篇
  2017年   260篇
  2016年   327篇
  2015年   239篇
  2014年   380篇
  2013年   1101篇
  2012年   664篇
  2011年   871篇
  2010年   674篇
  2009年   663篇
  2008年   859篇
  2007年   871篇
  2006年   685篇
  2005年   719篇
  2004年   559篇
  2003年   570篇
  2002年   509篇
  2001年   329篇
  2000年   301篇
  1999年   303篇
  1998年   316篇
  1997年   301篇
  1996年   301篇
  1995年   333篇
  1994年   267篇
  1993年   304篇
  1992年   272篇
  1991年   164篇
  1990年   237篇
  1989年   283篇
  1988年   204篇
  1987年   215篇
  1986年   211篇
  1985年   265篇
  1984年   258篇
  1983年   227篇
  1982年   217篇
  1981年   213篇
  1980年   175篇
  1979年   187篇
  1978年   176篇
  1977年   177篇
  1976年   148篇
  1975年   178篇
  1974年   165篇
  1973年   133篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
93.
94.
Abstract

A species of artificial organism in which individuals consist of freely interacting elementary components enclosed in an expandible envelope is described. Some organisms of this species are shown to be universal instruction-obeying mechanisms. Several procedures by which such artificial organisms might reproduce are presented and discussed.  相似文献   
95.
Abstract

A preliminary investigation of the role of look-ahead in one-person games is presented. The use of look-ahead in comparing the effectiveness of different heuristic functions is discussed. There is a survey of recent work in tree-searching including that of Doran and Michie [4], Hart, Nilsson, and Raphael [7] and Pohl [17]–[19]. Based on some of Pohl's results, two theorems are proven in Section 2. These suggest a possible use for look-ahead. Some experimental results are presented in Section 3 which satisfy to a limited degree the aforementioned theorems, and some additional observations are made. In conclusion, an attempt is presented to relate look-ahead to the notion of “informedness” introduced by Hart, Nilsson, and Raphael. Finally, some further directions for research are suggested.  相似文献   
96.
97.
98.
99.
American culture is filled with cultural products. Yet few studies have investigated how changes in cultural products correspond to changes in psychological traits and emotions. The current research fills this gap by testing the hypothesis that one cultural product—word use in popular song lyrics—changes over time in harmony with cultural changes in individualistic traits. Linguistic analyses of the most popular songs from 1980–2007 demonstrated changes in word use that mirror psychological change. Over time, use of words related to self-focus and antisocial behavior increased, whereas words related to other-focus, social interactions, and positive emotion decreased. These findings offer novel evidence regarding the need to investigate how changes in the tangible artifacts of the sociocultural environment can provide a window into understanding cultural changes in psychological processes. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
100.
A novel disposable electrochemical immunosensor for highly selective and sensitive detection of organophosphorylated butyrylcholinesterase (OP‐BChE), a specific biomarker for exposure to toxic organophosphorus agents, is presented. In this new approach, zirconia nanoparticles (ZrO2) were employed to selectively capture the OP moiety of OP‐BChE adducts, followed by quantum dot (QD)‐tagged anti‐BChE antibodies for amplified quantification. The captured CdSe‐QD tags can be sensitively detected by stripping voltammetry using an in situ bismuth‐plating method. The OP agent, diisopropylfluorophosphate (DFP), was selected to prepare OP‐BChE adducts in various matrices. The formation of OP‐BChE adducts in plasma sample was confirmed using mass spectroscopy. The developed electrochemical immunosensor demonstrates a highly linear voltammetric response over the range of 0.1 to 30 nM OP‐BChE, with a detection limit of 0.03 nM (based on signal/noise = 3), coupled with a good reproducibility (relative standard deviation 4.5%). Moreover, the immunosensor has been validated with biomonitoring of OP‐BChE adducts in the plasma samples. This novel nanoparticle‐based electrochemical immunosensor thus provides an alternative way for designing a sensitive and cost‐effective sensing platform for on‐site screening/evaluating exposure to a variety of OP agents.  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