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   10633篇
  免费   363篇
  国内免费   6篇
电工技术   118篇
综合类   2篇
化学工业   1854篇
金属工艺   151篇
机械仪表   240篇
建筑科学   442篇
矿业工程   24篇
能源动力   337篇
轻工业   1090篇
水利工程   137篇
石油天然气   42篇
武器工业   2篇
无线电   694篇
一般工业技术   1631篇
冶金工业   2973篇
原子能技术   52篇
自动化技术   1213篇
  2023年   48篇
  2022年   87篇
  2021年   201篇
  2020年   135篇
  2019年   163篇
  2018年   185篇
  2017年   170篇
  2016年   217篇
  2015年   154篇
  2014年   231篇
  2013年   536篇
  2012年   435篇
  2011年   684篇
  2010年   524篇
  2009年   444篇
  2008年   555篇
  2007年   546篇
  2006年   465篇
  2005年   437篇
  2004年   333篇
  2003年   326篇
  2002年   347篇
  2001年   204篇
  2000年   187篇
  1999年   200篇
  1998年   367篇
  1997年   268篇
  1996年   241篇
  1995年   197篇
  1994年   187篇
  1993年   178篇
  1992年   132篇
  1991年   75篇
  1990年   112篇
  1989年   108篇
  1988年   100篇
  1987年   80篇
  1986年   116篇
  1985年   95篇
  1984年   81篇
  1983年   73篇
  1982年   68篇
  1981年   67篇
  1980年   57篇
  1979年   54篇
  1978年   60篇
  1977年   73篇
  1976年   78篇
  1975年   54篇
  1974年   42篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Identifying markets for new or improved products for minor crops threatened with extinction is one critical component of any strategy intended to enhance prospects for sustainable production and use. Typically, however, activities linked to the sustainability of these commodities avoid addressing questions associated with assessing their commercial potential. After a brief review of this avoidance syndrome, this article presents a sample of practical, low-cost procedures to help evaluate the market prospects and procedures for crops like quinoa, while citing references to other methodological materials covering similar topics.  相似文献   
53.
Reports an error in the original article by E. A. Maylor (Psychology and Aging, 1993[Sep], Vol 8[3], 420–428). There is an error in the picture recognition data. This was one of the tasks administered in an earlier group testing session (see page 421). The number of false positives for an older S was incorrectly entered onto the data sheet as 31 instead of only 13. (The following abstract of this article originally appeared in record 1994-01191-001.) Ss (aged 52–83 yrs) named 30 famous people 4 times over the course of an hour and responded to 2 targets (a beard and a pipe) by marking the trial number on the response sheet. Initial performance in the prospective memory task was related only to a measure of incidental learning. Subsequent forgetting (i.e., success followed by failure) occurred more often for older Ss than for younger Ss, but there was no difference between the age groups in recovery (i.e., failure followed by success). Forgetting was predicted by age, even after a composite measure of general ability was included in the regression. Recovery was related to general ability alone. Results both replicate and extend those from a reanalysis of a previous study (E. A. Maylor, 1990). They provide a striking contrast with the effect of age on retrospective memory.… (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
54.
55.
56.
Monitoring respiratory epithelial biology may reveal individuals with incipient lung cancer. The expression of neuroendocrine (NE) markers in pulmonary epithelium is thought to be central to lung development, repair of injury and may contribute to carcinogenesis. In this study, we evaluate several candidate NE markers to determine the feasibility of prospective analysis of clinical specimens. The potential NE markers include the enzyme L-DOPA decarboxylase (DDC), the neuropeptide gastrin releasing peptide (GRP), and peptidyl-glycine alpha-amidating monooxygenase (PAM), the bifunctional enzyme responsible for the final bioactivation step of many neuropeptides. A comparison of PAM activity and DDC levels in 30 lung cancer cell lines indicated that peptide amidating activity may be an indicator of NE status. Bronchoalveolar lavage (BAL) fluid from subjects at risk of developing second primary lung cancer and from volunteers was obtained. The activity of the first PAM enzyme, peptidylglycine alpha-hydroxylating monooxygenase (PHM), ranged from not detectable to 507 pmol/h/mg protein in 57 specimens. The second PAM enzyme, peptidylamidoglycolate lyase (PAL), ranged from not detectable to 414 pmol/h/mg protein in 56 specimens. Using cluster analysis by the average linkage method, a group of enzyme values with PHM greater than 230 pmol/h/mg protein was determined. Long-term follow-up of these patients for new second primary lung cancers may help to determine the potential predictive value of PAM detected in the BAL fluid.  相似文献   
57.
58.
59.
60.
A crucial step in manufacturing microcircuits is the wire bonding process in which a very thin gold wire must be formed to connect two surfaces in the microcircuit. The quality of the wire bond can be measured by visual inspection and a pull test—both of which are high-reliability, high-cost approaches to statistical process control. Westinghouse wanted to develop a high-reliability, low-cost quality assurance system. In this paper, we report on a year-long study to construct a neural network model that is capable of predicting the quality of wire bonds. The results of our modeling efforts reveal that neural networks are useful tools for statistical process control problems.  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