全文获取类型
收费全文 | 18305篇 |
免费 | 2172篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 1388篇 |
综合类 | 404篇 |
化学工业 | 8900篇 |
金属工艺 | 278篇 |
机械仪表 | 390篇 |
建筑科学 | 721篇 |
矿业工程 | 176篇 |
能源动力 | 118篇 |
轻工业 | 1945篇 |
水利工程 | 125篇 |
石油天然气 | 69篇 |
无线电 | 395篇 |
一般工业技术 | 3027篇 |
冶金工业 | 388篇 |
原子能技术 | 31篇 |
自动化技术 | 2128篇 |
出版年
2023年 | 618篇 |
2022年 | 325篇 |
2021年 | 684篇 |
2020年 | 678篇 |
2019年 | 591篇 |
2018年 | 560篇 |
2017年 | 388篇 |
2016年 | 628篇 |
2015年 | 799篇 |
2014年 | 834篇 |
2013年 | 1423篇 |
2012年 | 564篇 |
2011年 | 452篇 |
2010年 | 801篇 |
2009年 | 940篇 |
2008年 | 442篇 |
2007年 | 424篇 |
2006年 | 310篇 |
2005年 | 294篇 |
2004年 | 250篇 |
2003年 | 236篇 |
1998年 | 212篇 |
1997年 | 167篇 |
1996年 | 219篇 |
1995年 | 205篇 |
1994年 | 183篇 |
1993年 | 242篇 |
1992年 | 191篇 |
1990年 | 182篇 |
1989年 | 194篇 |
1988年 | 150篇 |
1987年 | 185篇 |
1986年 | 195篇 |
1985年 | 192篇 |
1984年 | 191篇 |
1983年 | 198篇 |
1982年 | 171篇 |
1981年 | 227篇 |
1980年 | 179篇 |
1979年 | 181篇 |
1978年 | 142篇 |
1977年 | 162篇 |
1976年 | 166篇 |
1975年 | 212篇 |
1974年 | 200篇 |
1973年 | 375篇 |
1972年 | 226篇 |
1971年 | 155篇 |
1970年 | 158篇 |
1968年 | 162篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
S Knecht M Deppe EB Ringelstein M Wirtz H Lohmann B Dr?ger T Huber H Henningsen 《Canadian Metallurgical Quarterly》1998,29(6):1155-1159
BACKGROUND AND PURPOSE: Since functional transcranial Doppler ultrasonography (fTCD) allows convenient and fully automated quantification of language lateralization, it seems ideal for longitudinal studies of perfusion changes during deterioration as well as recovery of language functions. However, during serial examinations, the technical, stochastic, and physiological variabilities of cerebral blood flow velocities (CBFV) have to be considered. Therefore, before fTCD is accepted as a tool for evaluation of changes in lateralization in the diseased state, its reliability in healthy subjects needs to be determined. METHODS: We performed fTCD during a word generation task based on a previously validated technique with automated calculation of the averaged CBFV differences in the middle cerebral arteries providing an index of lateralization (LI). RESULTS: (1) The accuracy of the LI as assessed by the confidence interval was better than 1% of the mean hemispheric difference. (2) On repeated examination, LIs obtained from 10 subjects showed a high test-retest reproducibility (Pearson product moment correlation coefficient r = 0.95, P < 0.0001). (3) On 10 repeated assessments of LI in the same subject, no practice effects were detected. CONCLUSIONS: Functional TCD is a suitable and very robust tool for the longitudinal quantitative measurement of cerebral language lateralization. 相似文献
32.
33.
34.
35.
Bei der Model Driven Architecture (MDA) bilden Modelle die zentralen Elemente des Softwareentwicklungsprozesses. Ziel ist es, plattformspezifische Modelle möglichst automatisiert aus plattformunabhängigen Modellen abzuleiten. Dadurch soll der Aufwand der Softwareentwicklung verringert und die Adaptierung an neue Technologien erleichtert werden.*Vorschläge an Prof. Dr. Frank Puppe oder Dieter Steinbauer Alle „Aktuellen Schlagwörter“ seit 1988 finden Sie unter: www.ai-wuerzburg.de/as 相似文献
36.
Dr. V. Recina Dr. D. Lundström B. Karlsson 《Metallurgical and Materials Transactions A》2002,33(9):2869-2881
The influence of chemical composition on the microstructure of the γ-titanium aluminide alloy Ti-48Al-2W-0.5Si (at. pct) and the accompanying tensile, low-cycle fatigue, and creep properties
has been evaluated. The study showed that small variations in chemical composition and casting procedures resulted in considerable
variations in the microstructure, yielding vastly different mechanical properties. Low contents of aluminum and tungsten led
to a coarse-grained lamellar (γ/α
2) microstructure with high creep resistance. A composition close to the nominal one produced a duplex (γ+γ/α
2) structure with favorable strength, ductility, and low-cycle fatigue properties. By controlling the solidification and cooling
rates at casting, a pseudoduplex (PS-DP) microstructure with a unique combination of high strength and high fatigue and creep
resistance can be obtained. These unique properties can be explained by the diffuse boundaries between the relatively small
γ grains and the neighboring lamellar colonies, combined with semicoherent interfaces between the γ and α
2 phases. At tensile and low-cycle fatigue loading, these boundaries act like high-angle boundaries, producing a virtually
fine-grained material promoting strength, whereas at creep loading, grain-boundary sliding is hindered in the semicoherent
interfaces leading to high creep resistance. 相似文献
37.
38.
Dr. H. -J. Dobner 《Computing》1987,38(3):209-218
This article describes a newly developed and implemented method for computing guaranteed errorbounds for the solution of hyperbolic initial value problems. The basic concepts—modified fixed point theorems and approximated operators—allow an a posteriori error-estimation automatically. Therefore, no a priori knowledge of Lipschitz constants, monotonicity properties or additional error analysis is necessary. 相似文献
39.
40.