全文获取类型
收费全文 | 103610篇 |
免费 | 1595篇 |
国内免费 | 431篇 |
专业分类
电工技术 | 981篇 |
综合类 | 2343篇 |
化学工业 | 15634篇 |
金属工艺 | 5205篇 |
机械仪表 | 3366篇 |
建筑科学 | 3047篇 |
矿业工程 | 648篇 |
能源动力 | 1633篇 |
轻工业 | 4959篇 |
水利工程 | 1518篇 |
石油天然气 | 547篇 |
武器工业 | 1篇 |
无线电 | 10599篇 |
一般工业技术 | 19524篇 |
冶金工业 | 7109篇 |
原子能技术 | 419篇 |
自动化技术 | 28103篇 |
出版年
2022年 | 124篇 |
2021年 | 240篇 |
2020年 | 200篇 |
2019年 | 266篇 |
2018年 | 14680篇 |
2017年 | 13603篇 |
2016年 | 10243篇 |
2015年 | 887篇 |
2014年 | 674篇 |
2013年 | 1416篇 |
2012年 | 3843篇 |
2011年 | 10282篇 |
2010年 | 8968篇 |
2009年 | 6252篇 |
2008年 | 7587篇 |
2007年 | 8603篇 |
2006年 | 885篇 |
2005年 | 1917篇 |
2004年 | 1758篇 |
2003年 | 1757篇 |
2002年 | 1120篇 |
2001年 | 465篇 |
2000年 | 540篇 |
1999年 | 418篇 |
1998年 | 487篇 |
1997年 | 412篇 |
1996年 | 418篇 |
1995年 | 370篇 |
1994年 | 317篇 |
1993年 | 367篇 |
1992年 | 323篇 |
1991年 | 249篇 |
1990年 | 273篇 |
1989年 | 279篇 |
1988年 | 272篇 |
1987年 | 251篇 |
1986年 | 282篇 |
1985年 | 298篇 |
1984年 | 297篇 |
1983年 | 291篇 |
1982年 | 231篇 |
1981年 | 258篇 |
1980年 | 253篇 |
1979年 | 251篇 |
1978年 | 227篇 |
1977年 | 229篇 |
1976年 | 205篇 |
1975年 | 196篇 |
1974年 | 174篇 |
1973年 | 179篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
This letter presents some further results on the local stability in equilibrium for Internet congestion control algorithm proposed by Low et al., (IEEE/ACM Transactions on Networking, 1999). The propagation delay d(t) is assumed to be time-varying and have maximum and minimum delay bounds (i.e., d/sub m//spl les/d(t)/spl les/d/sub M/), which is more general than the assumption (0相似文献
122.
The stress intensity factors for a short crack partially penetrating an inclusion of arbitrary shape
Some approximate solutions for predicting the stress intensity factor of a short crack penetrating an inclusion of arbitrary
shape have been developed under mode I and mode II loading conditions. The derivation of the fundamental formula is based
on the transformation toughening theory. The transformation strains in the inclusion are induced by the crack-tip field and
remotely applied stresses, and approximately evaluated by the Eshelby equivalent inclusion theory. As validated by detailed
finite element (FE) analyses, the developed solutions have good accuracy for different inclusion shape and for a wide range
of modulus ratio between inclusion and matrix material. 相似文献
123.
An overview of nondestructive evaluation methods 总被引:1,自引:0,他引:1
Marvin Trimm 《Journal of Failure Analysis and Prevention》2003,3(3):17-31
ondestructive evaluation is described as nondestructive testing (NDT), nondestructive inspection (NDI), and nondestructive
examination (NDE). The activities associated with the evaluation include testing, inspection, and examination and primarily
involve looking at (or through) and/or measuring some characteristic of an object. Frequently there is a desire to determine
some characteristic of the object or to determine whether the object contains irregularities, discontinuities, or flaws. These
examinations, inspections, or tests are used to determine the physical soundness of a material without impairing its usefulness.
Nondestructive evaluation is a powerful tool that can help assure safety, quality, and reliability; increase productivity;
decrease liability; protect the environment; and save money. In this article, nondestructive evaluation is represented by
the acronym NDE. 相似文献
124.
Butler Emily A.; Egloff Boris; Wlhelm Frank H.; Smith Nancy C.; Erickson Elizabeth A.; Gross James J. 《Canadian Metallurgical Quarterly》2003,3(1):48
At times, people keep their emotions from showing during social interactions. The authors' analysis suggests that such expressive suppression should disrupt communication and increase stress levels. To test this hypothesis, the authors conducted 2 studies in which unacquainted pairs of women discussed an upsetting topic. In Study 1, one member of each pair was randomly assigned to (a) suppress her emotional behavior, (b) respond naturally, or (c) cognitively reappraise in a way that reduced emotional responding. Suppression alone disrupted communication and magnified blood pressure responses in the suppressors' partners. In Study 2, suppression had a negative impact on the regulators' emotional experience and increased blood pressure in both regulators and their partners. Suppression also reduced rapport and inhibited relationship formation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
125.
Nguyen An Tien I. Ya. Mittova O. V. Almjasheva S. A. Kirillova V. V. Gusarov 《Glass Physics and Chemistry》2008,34(6):756-761
Nanocrystalline LaFeO3 is prepared by the dehydration of coprecipitated lanthanum and iron(III) hydroxides. It is shown that the behavior of the samples during heating and the size distribution of LaFeO3 nanocrystals can be considerably different depending on the scheme used for coprecipitation of lanthanum and iron hydroxides; independently of the method employed for coprecipitation of the initial compounds, sintering of the samples at 950°C leads to the formation of lanthanum orthoferrite crystals up to 100 nm in size. 相似文献
126.
Vjacheslav V. Zuev 《Journal of Polymer Research》2008,15(5):351-356
Functionalized polyanilines containing biphenyl, terphenyl, carbazole, anthracene, and 4-n-hexylphenyl moieties were synthesized though the reaction of polyaniline in emeraldine base form with sodium salt of corresponding
vinylketoaromatics with quantitative yields. Polymers were characterized with Fourier transform infrared spectroscopy, proton
nuclear magnetic resonance spectroscopy, and thermogravimetry. The emission characteristics of these polymers in N-methyl-2-pyrrolidone solution were examined. The functionalized polyanilines exhibited an intense green emission. 相似文献
127.
We propose two new antidiffusive schemes for advection (or linear transport), one of them being a mixture of Roe’s Super-Bee
scheme and of the “Ultra-Bee” scheme. We show how to apply these schemes to treat time-dependent first order Hamilton–Jacobi–Bellman
equations with discontinuous initial data, possibly infinitely-valued. Numerical tests are proposed, in one and two space
dimensions, in order to validate the methods
AMS subject classifications. Primary 65M12, Secondary 58J47 相似文献
128.
Gokhan Tur 《Machine Learning》2007,69(1):55-74
We propose three methods for extending the Boosting family of classifiers motivated by the real-life problems we have encountered. First, we propose a semisupervised learning method for exploiting the unlabeled data in Boosting. We then present a novel classification model adaptation method. The goal of adaptation is optimizing an existing model for a new target application, which is similar to the previous one but may have different classes or class distributions. Finally, we present an efficient and effective cost-sensitive classification method that extends Boosting to allow for weighted classes. We evaluated these methods for call classification in the AT&;T VoiceTone® spoken language understanding system. Our results indicate that it is possible to obtain the same classification performance by using 30% less labeled data when the unlabeled data is utilized through semisupervised learning. Using model adaptation we can achieve the same classification accuracy using less than half of the labeled data from the new application. Finally, we present significant improvements in the “important” (i.e., higher weighted) classes without a significant loss in overall performance using the proposed cost-sensitive classification method. 相似文献
129.
Matthias Zobel Joachim Denzler Benno Heigl Elmar Nöth Dietrich Paulus Jochen Schmidt Georg Stemmer 《Machine Vision and Applications》2003,14(1):26-34
Abstract. This contribution introduces MOBSY, a fully integrated, autonomous mobile service robot system. It acts as an automatic dialogue-based
receptionist for visitors to our institute. MOBSY incorporates many techniques from different research areas into one working
stand-alone system. The techniques involved range from computer vision over speech understanding to classical robotics.
Along with the two main aspects of vision and speech, we also focus on the integration aspect, both on the methodological
and on the technical level. We describe the task and the techniques involved. Finally, we discuss the experiences that we
gained with MOBSY during a live performance at our institute. 相似文献
130.