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   755篇
  免费   49篇
  国内免费   1篇
电工技术   7篇
综合类   3篇
化学工业   132篇
金属工艺   14篇
机械仪表   18篇
建筑科学   24篇
能源动力   17篇
轻工业   127篇
水利工程   4篇
石油天然气   1篇
无线电   92篇
一般工业技术   106篇
冶金工业   55篇
原子能技术   3篇
自动化技术   202篇
  2023年   10篇
  2022年   6篇
  2021年   25篇
  2020年   25篇
  2019年   20篇
  2018年   31篇
  2017年   37篇
  2016年   40篇
  2015年   40篇
  2014年   39篇
  2013年   71篇
  2012年   48篇
  2011年   42篇
  2010年   48篇
  2009年   32篇
  2008年   29篇
  2007年   20篇
  2006年   20篇
  2005年   17篇
  2004年   12篇
  2003年   15篇
  2002年   13篇
  2001年   7篇
  2000年   4篇
  1999年   10篇
  1998年   19篇
  1997年   14篇
  1996年   11篇
  1995年   20篇
  1994年   10篇
  1993年   8篇
  1992年   7篇
  1991年   14篇
  1990年   3篇
  1989年   2篇
  1988年   2篇
  1987年   6篇
  1986年   3篇
  1985年   2篇
  1984年   1篇
  1983年   5篇
  1982年   1篇
  1981年   4篇
  1980年   2篇
  1978年   1篇
  1976年   4篇
  1975年   3篇
  1974年   1篇
  1973年   1篇
排序方式: 共有805条查询结果,搜索用时 15 毫秒
41.
In this paper, problems that occur when working with welds formed of high-alloy steels to restore their passive layers, damaged as a result of temperature impact, are discussed. Particular attention was paid to the procedures concerning aggressive etching agents during and after completion of the passivation processes (waste neutralization and utilization).  相似文献   
42.
The objective of the present work was to determine the nutrient and polyphenolic composition of dried strawberry press cake (SPC), as well as that of its seedless fraction, termed exhausted strawberry flesh (ESF). The study materials were obtained over three consecutive years from an industrial facility manufacturing concentrated fruit juices. On average, SPC consists of 40 % seeds, 3.5 % sand, and about 55 % ESF. In the dry matter of SPC and ESF, the mean content of fat is 9.8 and 3.5 %, protein 17.3 and 20.4 %, and total polyphenols 3,449 and 5,410 mg/100 g, respectively. Both materials are rich in total dietary fiber, whose content amounts to 60 %. The predominant polyphenols in SPC and ESF are flavanols and ellagitannins, which collectively constitute over 95 % of the determined total polyphenol content. In ESF composition, of note is the high content of the strawberry ellagitannin, agrimoniin, which is approximately 1,000 mg/100 g DW (dry weight). SPC has the disadvantage of being highly contaminated with sand (3.4 %), which accumulates in ESF (5.6 %). However, as compared to SPC, ESF contains approximately 20 % more proteins and almost three times less fat. Based on our results, it appears that SPC may be considered a potential raw material for seed recovery. Moreover, dried strawberry press cake, and especially its seedless fraction (ESF), despite substantial contamination with sand, may be used as rich and widely available raw material for the extraction of proanthocyanidins and/or ellagitannins, and especially dimeric agrimoniin.  相似文献   
43.
The theoretical model presented in this paper emerged from several different disciplines. This model proposes that the attainment of happiness is linked to the self, and more particularly to the structure of the self. We support the idea that the perception of a structured self, which takes the form of a permanent, independent and solid entity leads to self-centered psychological functioning, and this seems to be a significant source of both affliction and fluctuating happiness. Contrary to this, a selfless psychological functioning emerges when perception of the self is flexible (i.e., a dynamic network of transitory relations), and this seems to be a source of authentic-durable happiness. In this paper, these two aspects of psychological functioning and their underlying processes will be presented. We will also explore the potential mechanisms that shape them. We will conclude with an examination of possible applications of our theory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
44.
X-ray Photoelectron Spectroscopy (XPS) was used to study the influence of low energy Ar+ ion bombardment, electron bombardment and Pt deposition on the SrTiO3 (STO) single crystal electronic structure. Atomic composition changes were found and attributed to chemical reconstruction of the STO surface. A clear correlation between the presence of conducting, low Ti oxidation states in valence band and core level changes was detected. A strong effect caused by electron irradiation was ascribed to the electroreduction process. The influence of lanthanum doping on surface instability of STO was also discussed. The La doped sample (STO: 3,75% La) was found to be modified upon Pt metal deposition to a higher degree than pure STO crystal.  相似文献   
45.
We develop a quantifier-free logic for deriving consequences of multialgebraic theories. Multialgebras are used as models for nondeterminism in the context of algebraic specifications. They are many sorted algebras with set-valued operations. Formulae are sequents over atoms allowing one to state set-inclusion or identity of 1-element sets (determinacy). We introduce a sound and weakly complete Rasiowa–Sikorski (R–S) logic for proving multialgebraic tautologies. We then extend this system for proving consequences of specifications based on translation of finite theories into logical formulae. Finally, we show how such a translation may be avoided—introduction of the specific cut rules leads to a sound and strongly complete Gentzen system for proving directly consequences of specifications. Besides giving examples of the general techniques of R–S and the specific cut rules, we improve the earlier logics for multialgebras by providing means to handle empty carriers (as well as empty result-sets) without the use of quantifiers, and to derive consequences of theories without translation into another format and without using general cut.  相似文献   
46.
The authors have fabricated 0.1-μm T-gate pseudomorphic (PM) InGaAs power high-electron-mobility transistors (HEMTs) with record power and gain performance at 94 GHz. Devices with 40-μm gate peripheries achieved 10.6-mW output power with 7.3-dB gain and 14.3% power-added efficiency (PAE). Devices with 160-μm gate peripheries achieved 62.7-mW output power with 4.0-dB gain and 13.2% PAE. The authors believe the superior performance of these devices is due to the combination of a short 0.1-μm T-gate, high-quality material, optimized device profile, and the reduction in source inductance due to source vias  相似文献   
47.
48.
Mechanism of adsorption of lower aliphatic alcohols and amines on active carbon surfaces has been studied. Interpretation of the results required application of the modified Polanyi-Dubinin potential theory. A basic difference in adsorption of alcohols and amines has been found. Thus, the degree of alcohols association is lower in the adsorbed phase than in the liquid phase, whereas the reverse is observed for amines.  相似文献   
49.
50.
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