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   10470篇
  免费   213篇
  国内免费   15篇
电工技术   111篇
综合类   6篇
化学工业   1666篇
金属工艺   194篇
机械仪表   275篇
建筑科学   419篇
矿业工程   60篇
能源动力   239篇
轻工业   880篇
水利工程   86篇
石油天然气   29篇
武器工业   1篇
无线电   919篇
一般工业技术   1706篇
冶金工业   2966篇
原子能技术   96篇
自动化技术   1045篇
  2022年   55篇
  2021年   83篇
  2020年   60篇
  2019年   81篇
  2018年   111篇
  2017年   106篇
  2016年   129篇
  2015年   109篇
  2014年   149篇
  2013年   510篇
  2012年   285篇
  2011年   380篇
  2010年   345篇
  2009年   311篇
  2008年   362篇
  2007年   348篇
  2006年   284篇
  2005年   315篇
  2004年   247篇
  2003年   261篇
  2002年   243篇
  2001年   193篇
  2000年   227篇
  1999年   191篇
  1998年   745篇
  1997年   540篇
  1996年   393篇
  1995年   319篇
  1994年   276篇
  1993年   280篇
  1992年   129篇
  1991年   119篇
  1990年   139篇
  1989年   150篇
  1988年   141篇
  1987年   109篇
  1986年   101篇
  1985年   138篇
  1984年   140篇
  1983年   108篇
  1982年   92篇
  1981年   101篇
  1980年   97篇
  1979年   92篇
  1978年   102篇
  1977年   137篇
  1976年   221篇
  1975年   82篇
  1974年   78篇
  1973年   70篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Jones  C. 《Computer》1995,28(1):76-77
The relationship between office size and noise level is one of the most significant, yet least investigated, factors affecting software productivity. According to Tom DeMarco and Tim Lister (1992), US programmers with more than 80 square feet of private, noise-free office space consistently outperform programmers who occupy two- or three-person cubicles. The result was the Santa Teresa Programming Laboratory in San Jose, California, which opened in 1978. The author discusses some requirements of an optimal programming office environment. He considers the effectiveness of home working  相似文献   
32.
33.
The work presented in this paper shows how the association of proprioceptive and exteroceptive stimuli can enable a Kohonen neural network, controlling a robot arm, to learn hand-eye co-ordination so that the arm can reach for and track a visually presented target. The approach presented in this work assumes no a priorimodel of arm kinematics or of the imaging characteristics of the cameras. No explicit representation, such as homogeneous transformations, is used for the specification of robot pose, and camera calibration and triangulation are done implicitly as the system adapts and learns its hand-eye co-ordination by experience. This research is validated on physical devices and not by simulation.  相似文献   
34.
This paper describes an approach, conceptual framework, and software architecture for dynamic reconfiguration of the order picking system. The research and development project was sponsored by the Material Handling Research Center (MHRC), a National Science Foundation sponsored Cooperative Industry/University Research Center. The storage configuration is assumed to be an in-the-aisle order picking system in which stockkeeping units (SKUs) can occupy variable capacity storage locations and stock-splitting is allowed among zones (clusters). The product mix may include multiple product families with different life cycles, correlated demand within families and commonality of demand across families.  相似文献   
35.
36.
Nitrification kinetics are important for process design, optimization, and capacity rating of activated sludge wastewater treatment plants. A Water Environment Research Foundation (WERF) project on Methods for Wastewater Characterization in Activated Sludge Modeling (WERF, 2003) focused significantly on the development of procedures for measuring the nitrifier maximum specific growth rate, micro(AUT). In addition, the importance of (and lack of data for) the nitrifier decay rate, b(AUT), was identified. This paper describes three bench-scale methods for measuring micro(AUT): the Low F/M SBR, Washout and High F/M methods. During the WERF project, the importance of pH and temperature control was investigated briefly; this paper summarizes further experimental work performed to address these issues. A summary of micro(AUT) measurements in a number of locations and using the different measurement techniques is provided.  相似文献   
37.
The magnitude of the Stroop effect is known to be modulated by the proportion of trials on which the irrelevant word and relevant ink color correspond. This has often been attributed to a conscious strategy of increased (or decreased) reliance on the irrelevant words when these are more likely (or less likely) to correspond to the ink colors. However, the present data from a Stroop-like task involving successively presented arrows indicate instead that this type of modulation can be automatic because it can occur even if the irrelevant stimuli are not phenomenally visible. In this case participants cannot determine the proportion of compatible trials to direct their strategy. An automatic, item-specific associative interpretation can account for these findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
38.
39.
A gypsum wall assembly was exposed to an intense real‐scale compartment fire. For the wall assembly, temperatures were measured at the exposed face, within the stud cavity, and at the unexposed face during the fire exposure. Total heat flux gauges were used to measure the temporal variation of the energy incident on the walls, and cameras, both visual and infrared, were used to image the unexposed face of the wall assembly during the fire exposure. The behaviour of the wall assembly under the fire load is discussed as are current model results for a simulation of the fire test. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
40.
Organochlorine analysis was performed on carcasses of 13 diving ducks from a 1981 wintering population that foraged on contaminated sediments in the lower Detroit River. Mean total PCB concentrations were 10 mg/kg for seven lesser scaups (Aythya affinis), 11 mg/kg for three greater scaups (A. marila), and 7.6 mg/kg for three goldeneyes (Bucephala clangula). Highest mean levels of other residues were measured for hexachlorobenzene (1.7 mg/kg) in goldeneyes, and transnonachlor (0.33 mg/kg) and 4,4’-DDE (1.3 mg/kg) in greater scaup. Quantitative analysis of 72 PCB congeners also was applied to water, seston, sediment, benthie oligochaetes, and carp from the same site. Principal congeners in most of the samples included some of the more toxic and persistent PCBs. Results of a multivariate analysis indicated that ratios of more conservative to less conservative PCBs did not vary significantly among ducks (α = .05), but differed from those in carp, oligochaetes, and sediment. For the February through March period of fat mobilization, concentrations of total PCB in lipid were inversely correlated with percent lipid (r = 0.76) in ducks. The percentage of conservative PCBs increased slightly. The distribution and partitioning of organochlorines, including toxic PCB congeners, varied considerably within this water column-sediment-fauna ecosystem. Estimates of toxic exposure based on total PCB values may be unreliable.  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