全文获取类型
收费全文 | 3306篇 |
免费 | 42篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 34篇 |
综合类 | 2篇 |
化学工业 | 469篇 |
金属工艺 | 36篇 |
机械仪表 | 58篇 |
建筑科学 | 174篇 |
矿业工程 | 15篇 |
能源动力 | 68篇 |
轻工业 | 232篇 |
水利工程 | 12篇 |
石油天然气 | 19篇 |
无线电 | 234篇 |
一般工业技术 | 394篇 |
冶金工业 | 1195篇 |
原子能技术 | 28篇 |
自动化技术 | 382篇 |
出版年
2021年 | 18篇 |
2019年 | 22篇 |
2017年 | 21篇 |
2016年 | 28篇 |
2015年 | 22篇 |
2014年 | 37篇 |
2013年 | 145篇 |
2012年 | 72篇 |
2011年 | 116篇 |
2010年 | 94篇 |
2009年 | 82篇 |
2008年 | 115篇 |
2007年 | 104篇 |
2006年 | 113篇 |
2005年 | 77篇 |
2004年 | 78篇 |
2003年 | 84篇 |
2002年 | 82篇 |
2001年 | 60篇 |
2000年 | 59篇 |
1999年 | 67篇 |
1998年 | 151篇 |
1997年 | 106篇 |
1996年 | 100篇 |
1995年 | 93篇 |
1994年 | 84篇 |
1993年 | 77篇 |
1992年 | 63篇 |
1991年 | 37篇 |
1990年 | 53篇 |
1989年 | 56篇 |
1988年 | 64篇 |
1987年 | 58篇 |
1986年 | 56篇 |
1985年 | 59篇 |
1984年 | 49篇 |
1983年 | 56篇 |
1982年 | 55篇 |
1981年 | 38篇 |
1980年 | 51篇 |
1979年 | 46篇 |
1978年 | 34篇 |
1977年 | 43篇 |
1976年 | 50篇 |
1975年 | 42篇 |
1974年 | 44篇 |
1973年 | 34篇 |
1972年 | 26篇 |
1971年 | 17篇 |
1970年 | 17篇 |
排序方式: 共有3352条查询结果,搜索用时 15 毫秒
181.
Because ideal PrBa2Cu3O7 superconducts at 90 K, it should be replaced by RBa2–u Sr
u
Cu2MO8 (where R is a light-mass rare earth and M is Nb or, preferably, Ta) as the insulator of choice for YBa2Cu3O7 Josephson junction or microstructure technology. Furthermore, (110)- or (100)-oriented substrates of RSr2Cu2MO8 may provide an opportunity for optimal device fabrication. 相似文献
182.
Transaction-level determinants of transfer-pricing policy: evidence from the high-technology sector 总被引:1,自引:0,他引:1
This paper uses transaction cost economics (TCE) as the basisfor an empirical study of transfer pricingpricing ofintra-firm transactionsin a multi-divisional firm. Thestudy finds the evidence to support predictions that transaction-specificinvestment and quality requirements increase the likelihoodthat headquarters will centrally administer the pricing of transactionsbetween divisions. This article concludes that, just as transaction-costeconomizing plays a role in organizing transactions betweenfirms, it also affects organization of exchange within firms. 相似文献
183.
Howard BJ Liland A Beresford NA Andersson KG Cox G Gil JM Hunt J Nisbet A Oughton DH Voigt G 《Radiation protection dosimetry》2004,109(1-2):63-67
The STRATEGY project (sustainable restoration and long-term management of contaminated rural, urban and industrial ecosystems; www.strategy-ec.org.uk) addressed the need for a holistic decision framework for the selection of optimal remediation strategies for long-term sustainable management of contaminated areas in Western Europe. The project considered both technical and social aspects of implementing restoration strategies for urban and rural environments. The importance of considering socially relevant objectives in addition to the dose reduction was emphasised. A critical evaluation was carried out on 101 selected countermeasures, (including rural waste disposal options), a model was developed to aid optimising countermeasure strategies and a method of carrying out participatory decision-making suggested. The outputs of the project are described and critically evaluated. 相似文献
184.
Following bar-press shaping of 24 male albino rats to a discrete-trial fixed-ratio (FR) 5 schedule of reinforcement; 16 were trained to produce either hippocampal theta (7.5-8.5 Hz) or nontheta (4-5 Hz) activity, while 8 served as a matched interreinforcement time control (yoked to the theta group). All Ss then returned to the FR-5 schedule on the lever response for 15 days, followed by 12 days of extinction. Results indicate that hippocampal theta production was learned more slowly than nontheta production but resulted in increased resistance to extinction of the subsequently performed lever response. These data are viewed as supporting the hippocampal theta-frustration hypothesis proposed by H. Glazer in 1972. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
185.
Describes the role played by Benjamin Franklin in the demise of animal magnetism research. Franklin served on a commission appointed by the French Academy of Sciences whose subsequent report failed to support the work of F. A. Mesmer and his disciple C. Deslon. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
186.
187.
Furuya K. Miller B. Coldren L. Howard R. 《Quantum Electronics, IEEE Journal of》1982,18(10):1783-1789
We propose an efficient and simple optical interconnection between active semiconductor components by deposition and spin coating. Details of the waveguide design, the fabrication technique, and a promising material combination are given. Experimental results with an integrated laser-polyimide/SiOx (x sim 2 ) waveguide combination demonstrate low-threshold (2.0 kA/cm2) laser operation and a low-loss waveguide interconnection (81 percent coupling efficiency) on a GaInAsP/InP chip. 相似文献
188.
Reibstein David J.; Youngblood Stuart A.; Fromkin Howard L. 《Canadian Metallurgical Quarterly》1975,60(4):434
Studied how the number of choices confronting an individual influences his perceived decision freedom and, consequently, his satisfaction and consumption level. 72 college students, randomly assigned to 1 of 2 experimental conditions, were asked to select one soft drink flavor. Perceived decision freedom and consumption levels were significantly greater for those selecting from an enlarged-choice set, but there was no significant difference in the Ss' stated satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
189.
Howard L. Greene Richard F. Mostardi Richard F. Nokes 《Polymer Engineering and Science》1980,20(7):499-504
Results from two pilot studies using White Carneau pigeons on high cholesterol diets have demonstrated substantial reduction in arterial plaque accumulations when the birds were periodically injected with dilute aqueous solutions of a drag reducing polymer (Separan AP-30) so as to maintain circulating blood concentrations of approximately 60 ppm. Initiation of arterial plaque formation may be fluid-mechanically motivated such that regions subjected to fluid turbulence, rapidly developing boundary layers, and alternate separation and reattachment, arc; the most prone lo attack. Viscoelastic fluid response, as seen in drag reducing media, is known to alter such phenomena. Comparative documentation of plaque deposition in experimental as well as control birds shows significant differences in both the aortas and coronary arteries, at optical magnifications from 20 to 15000X. 相似文献
190.
Roback Howard B.; Webb Warren W.; Strassberg Donald 《Canadian Metallurgical Quarterly》1974,42(5):734
Administered the MMPI to 17 21-62 yr old male patients who did not pay their clinic bills and 17 patients who did pay their bills. MMPI and clinical data suggest greater reality disturbance and distortion for the non-fee paying group than for the fee-paying group, and that fee-payment behavior is situationally determined and not a generalized characteristic. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献