全文获取类型
收费全文 | 13811篇 |
免费 | 348篇 |
国内免费 | 21篇 |
专业分类
电工技术 | 192篇 |
综合类 | 12篇 |
化学工业 | 3038篇 |
金属工艺 | 228篇 |
机械仪表 | 284篇 |
建筑科学 | 646篇 |
矿业工程 | 97篇 |
能源动力 | 376篇 |
轻工业 | 969篇 |
水利工程 | 131篇 |
石油天然气 | 164篇 |
武器工业 | 1篇 |
无线电 | 838篇 |
一般工业技术 | 2031篇 |
冶金工业 | 3383篇 |
原子能技术 | 138篇 |
自动化技术 | 1652篇 |
出版年
2022年 | 118篇 |
2021年 | 169篇 |
2020年 | 144篇 |
2019年 | 159篇 |
2018年 | 179篇 |
2017年 | 182篇 |
2016年 | 205篇 |
2015年 | 164篇 |
2014年 | 228篇 |
2013年 | 809篇 |
2012年 | 445篇 |
2011年 | 619篇 |
2010年 | 399篇 |
2009年 | 438篇 |
2008年 | 565篇 |
2007年 | 547篇 |
2006年 | 537篇 |
2005年 | 447篇 |
2004年 | 364篇 |
2003年 | 362篇 |
2002年 | 372篇 |
2001年 | 238篇 |
2000年 | 234篇 |
1999年 | 252篇 |
1998年 | 225篇 |
1997年 | 234篇 |
1996年 | 242篇 |
1995年 | 241篇 |
1994年 | 246篇 |
1993年 | 297篇 |
1992年 | 248篇 |
1991年 | 184篇 |
1990年 | 202篇 |
1989年 | 217篇 |
1988年 | 173篇 |
1987年 | 216篇 |
1986年 | 205篇 |
1985年 | 249篇 |
1984年 | 227篇 |
1983年 | 202篇 |
1982年 | 184篇 |
1981年 | 194篇 |
1980年 | 162篇 |
1979年 | 182篇 |
1978年 | 183篇 |
1977年 | 138篇 |
1976年 | 147篇 |
1975年 | 180篇 |
1974年 | 135篇 |
1973年 | 135篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
11.
Connecting people across the “digital divide” is as much a social effort as a technological one. We are developing a community-centred
approach to learn how interaction techniques can compensate for poor communication across the digital divide. We have incorporated
the lessons learned regarding social intelligence design in an abstraction and in a device called the SoftBridge. The SoftBridge
allows communication to flow from endpoints through adapters, getting converted if necessary, and out to destination endpoints.
Field trials are underway with two communities in South Africa: disadvantaged Deaf users and an isolated rural community.
Initial lessons learned show that we have to design user interfaces that allow users to understand and cope with delay. We
also learned that social concerns are often more important than the technical issues in designing such systems. 相似文献
12.
Krenz William Robin Michael Barez Shirin Stark Lawrence 《IEEE transactions on bio-medical engineering》1985,(10):817-825
A model of the pathways controlling the size of the human pupil is presented. Computer simulation of this model demonstrates the role played by each of the elements in the pupil pathways. Simulations of the effects of drugs and a few common abnormalities in the system also help to illustrate the workings of the internal processes. Computer models of this type can be used as teaching aids or as tools for testing of hypotheses regarding the system. 相似文献
13.
The technique of analytical pyrolysis has been used to characterize 40 similar mid-rank western Kentucky coals of widely differing ASTM Gieseler plasticity. Certain pyrolysis/g.c. variables were shown to correlate well with both ASTM Gieseler and isothermal plasticity. Highly plastic coals were shown to exhibit certain characteristic peaks in the 450 °C pyrogram which were absent in the pyrogram of the non-plastic coals. Two coals, representing the two extremes in plasticity, were selected for further study. After extraction with solvents such as DMF the characteristic peaks were absent in the 450 °C pyrogram of the extraction residue of the highly plastic coal. These peaks were also shown to decrease with increasing severity of air oxidation of the plastic coal. This technique appears to be a useful tool for the analysis of mid-rank plastic coals and supports the view that the substances contained in the bitumen fraction of these coals are involved in the development of the plastic state. 相似文献
14.
The oxidation of chloro-5-10,15,20-tetramesitylporphyrinotoiron(III) with peroxyacids affords a reactive oxoiron(IV)-porphyrin cation radical species 2. The characterization of 2 and its oxochromium analogs 3, 4 and 5 are reviewed. The nature of reactive oxochromium species derived from chromyl reagents is also reviewed. The oxidation of triphenylphosphine by CrOTPP (11), CrOTTP (13) and CrOTMP (14) is described. Variations in the rate constants indicate that steric factors affect the rate of oxygen atom transfer. Activation parameters for the oxidation of triphenylphosphine by 14 are ΔH≠ = 6.96 kcal/mol and ΔS≠ = −39 eu. The oxidation of t-butylphenylcarbinol (18) by CrOTPP gave predominantly benzaldehyde via carbon—carbon bond cleavage while the chromium(III) porphyrin-catalyzed oxidation of 18 by iodosylbenzene afforded t-butylphenylketone. 相似文献
15.
van Baaren Rick B.; Maddux William W.; Chartrand Tanya L.; de Bouter Cris; van Knippenberg Ad 《Canadian Metallurgical Quarterly》2003,84(5):1093
The present studies demonstrated the moderation of self-construal orientation on mimicry. Recent research has indicated that an interdependent self-construal is associated with assimilation of the other to the self whereas an independent self-construal is associated with minimizing the influence of others on the self (H. R. Markus & S. Kitayama, 1991; D. Stapel & W. Koomen, 2001). Therefore, the authors hypothesized that an interdependent self-construal would be associated with more mimicry than an independent self-construal. When self-construal orientations were experimentally primed. as in Studies 1 and 2, independent self-construals produced less nonconscious mimicry than interdependent self-construals. When self-construals were examined as cultural differences with either a chronically dominant independent (Americans) or interdependent (Japanese) construal of the self, these results were replicated. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
16.
William F. Maloney 《Canadian Metallurgical Quarterly》2003,129(2):165-172
The satisfaction that a customer has with the construction product and construction services provided by a contractor has a direct influence on the customer’s willingness to select that contractor for future work. Labor and management working together have the opportunity to influence customer satisfaction. Activities at the contractor/craft worker level, the contractor/local union level, and the contractor association/local union level have the greatest potential to influence customer satisfaction. A precisely defined plan incorporating labor-management activities targeted at specific satisfaction factors will have the greatest likelihood of creating high customer satisfaction. 相似文献
17.
Presents an obituary for Douglas W. Bray, the inventor of the modern-day assessment center, a method used by thousands of organizations around the world to identify the best people for critical roles and to guide individuals in optimizing their talents. Bray's death in Englewood, New Jersey, on May 9, 2006, ended the extraordinary career of a pioneer in industrial/organizational (I/O) psychology who optimized the interplay of research and application. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
18.
William D. Tape John B. Kennedy Murty K. S. Madugula 《Canadian Metallurgical Quarterly》2007,11(1):91-98
The current methods of connecting the flanges of precast double tee members, and their respective short comings in specific situations, are described. A new carbon fiber-reinforced polymer (CFRP) flange-to-flange connection is proposed to eliminate the problems associated with repair requirements for the current connections. Design expressions for the currently used mechanical anchorage and the proposed CFRP connection are presented. A comparative calculation for the two systems is given. 相似文献
19.
Schmitter-Edgecombe Maureen; Marks William; Fahy John F. 《Canadian Metallurgical Quarterly》1993,7(2):136
The 2-process theory of semantic priming (J. H. Neely, 1977; M. I. Posner and C. R. Snyder, 1975) was used to determine the maintenance of automatic processes after severe closed head injury (CHI) and to determine whether processes that demand attention suffer a deficit. Ss with severe CHI (N?=?18,?>?2 yrs postinjury) and 18 matched control Ss completed a lexical decision task in which a category prime was followed by a target. Automatic and attentional priming were determined by orthogonally varying prime–target relatedness, expectancy, and stimulus onset asynchrony. Although the CHI Ss had slower reaction times (RTs) overall, there were no significant group differences in the magnitude of either the automatic or attentional component of semantic priming. The present results indicate the integrity of semantic processes and normal semantic priming in long-term patients with severe CHI. The results are discussed in relation to an attentional resource hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
20.