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   40389篇
  免费   1535篇
  国内免费   65篇
电工技术   418篇
综合类   34篇
化学工业   8196篇
金属工艺   765篇
机械仪表   810篇
建筑科学   2091篇
矿业工程   122篇
能源动力   1213篇
轻工业   3584篇
水利工程   456篇
石油天然气   128篇
武器工业   5篇
无线电   2819篇
一般工业技术   6765篇
冶金工业   7044篇
原子能技术   293篇
自动化技术   7246篇
  2023年   266篇
  2022年   609篇
  2021年   857篇
  2020年   562篇
  2019年   741篇
  2018年   932篇
  2017年   838篇
  2016年   964篇
  2015年   874篇
  2014年   1207篇
  2013年   2654篇
  2012年   1930篇
  2011年   2374篇
  2010年   1855篇
  2009年   1732篇
  2008年   1987篇
  2007年   1945篇
  2006年   1764篇
  2005年   1562篇
  2004年   1287篇
  2003年   1210篇
  2002年   1133篇
  2001年   760篇
  2000年   593篇
  1999年   658篇
  1998年   716篇
  1997年   667篇
  1996年   612篇
  1995年   620篇
  1994年   577篇
  1993年   539篇
  1992年   522篇
  1991年   311篇
  1990年   442篇
  1989年   413篇
  1988年   338篇
  1987年   364篇
  1986年   320篇
  1985年   427篇
  1984年   424篇
  1983年   327篇
  1982年   305篇
  1981年   290篇
  1980年   277篇
  1979年   275篇
  1978年   250篇
  1977年   231篇
  1976年   221篇
  1975年   200篇
  1974年   176篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
News section     
David Smith 《AI & Society》1991,5(4):360-361
  相似文献   
42.
People in different regions of the world live under different cultural and religious orders and derive various practical ethics from them. Some of these moral and religious principles are clearly more favorable for economic development than others. Yet such ethnological differences are regrettably absent from our prevailing theories of regional economic development. In this paper, culture is defined as a system of relatively slow processes of change — known as cultural arenas. A complex interface exists between these slower processes and the relatively faster ones (known as games). In attempting to assess the development prospects of any region, a key point to grasp is that this cultural interface may be self-organizing. Its future trajectory will therefore be uncertain. To the extent that the proposed system of slow processes may be construed as a region's cultural base, they may control the nature and achievable pace of that region's development.An earlier version of this paper was presented at a Conference onThe Economics of the Cities of Art, held in Venice from 13–15 May 1991.  相似文献   
43.
Replies to R. E. Roughton's (see record 1994-27310-001) response to D. K. Flaks's (see record 1993-23357-001) article on homophobia and the psychologists's role in psychoanalytic training institutes. Flaks commends attempts by the American Psychoanalytic Association to combat homophobia within the organization but notes potential problems that might limit its success. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
44.
Enucleation frequently and progressively causes an enophtalmus and atrophia of the inferior eyelid, thereby leading to a height deficiency. Buccal mucous grafts give rise to phenomena such as secondary retraction. This may have complex and painful post-operative outcomes. However, when a septal chondromucous graft is performed, the height in the inferior palpebral part becomes more aesthetic, more retentive and quickly allows the wearing of a more voluminous prosthesis. Thus, the notinable enophtalmus can be corrected and the aesthetic quality of the looking is substantially restored. The authors report this surgical procedure and the results obtained with 21 patients which appear to be particularly promising.  相似文献   
45.
The authors highlight several possible ways in which the construction industry could lower present emissions of the greenhouse gas, carbon dioxide. It is an excellent discussion document and is recommended reading.  相似文献   
46.
47.
Systemised serendipity for producing computer art   总被引:4,自引:0,他引:4  
Serendipity applied to Newton's method, and its derivative the Secant Method, produces unusual and beautiful fractal patterns. Serendipity may be systemised, for example, by the introduction of a perturbation parameter P1, [1] to facilitate searches for interesting pattern variations.  相似文献   
48.
49.
OBJECTIVE: To evaluate aspects of the natural history of AA amyloidosis complicating juvenile rheumatoid arthritis (JRA), and its response to therapy with chlorambucil. METHODS: Scintigraphy and 7-day turnover studies were performed in JRA patients with histologically proven (n = 35) or clinically suspected (n = 30) AA amyloidosis, following intravenous injection of 123I and 125I-labeled serum amyloid P component (SAP). Prospective monitoring studies were performed over 2-3 years in 20 patients with amyloidosis. All but 2 amyloidosis patients were treated with chlorambucil. RESULTS: Positive scanning results were obtained in all patients in whom imaging was performed within 12 years of positive biopsy findings of amyloid and in 5 patients with clinically suspected amyloidosis. Negative scanning results with normal SAP metabolism, indicating regression of amyloid, were obtained in 4 patients whose amyloidosis had been in full clinical remission for more than 12 years. Prospective monitoring studies in patients whose JRA-associated inflammatory activity was in remission demonstrated regression of amyloid in 8 patients and no substantial changes in 8 others; however, in 4 further patients with active inflammation, there was accumulation of amyloid. There was a very poor correlation between the amount of amyloid present at a particular site and the resultant organ dysfunction. CONCLUSION: Radiolabeled SAP scintigraphy and turnover studies are useful complementary tools in the diagnosis, screening, and quantitative monitoring of type AA amyloidosis in JRA. The amyloid deposits may progress and/or regress at different rates in different anatomic sites over short periods.  相似文献   
50.
We consider the problem of generating a large state-space in a distributed fashion. Unlike previously proposed solutions that partition the set of reachable states according to a hashing function provided by the user, we explore heuristic methods that completely automate the process. The first step is an initial random walk through the state space to initialize a search tree, duplicated in each processor. Then, the reachability graph is built in a distributed way, using the search tree to assign each newly found state to classes assigned to the available processors. Furthermore, we explore two remapping criteria that attempt to balance memory usage or future workload, respectively. We show how the cost of computing the global snapshot required for remapping will scale up for system sizes in the foreseeable future. An extensive set of results is presented to support our conclusions that remapping is extremely beneficial.  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