全文获取类型
收费全文 | 54485篇 |
免费 | 2209篇 |
国内免费 | 164篇 |
专业分类
电工技术 | 790篇 |
综合类 | 271篇 |
化学工业 | 10583篇 |
金属工艺 | 1183篇 |
机械仪表 | 1168篇 |
建筑科学 | 2101篇 |
矿业工程 | 249篇 |
能源动力 | 1132篇 |
轻工业 | 5984篇 |
水利工程 | 448篇 |
石油天然气 | 209篇 |
武器工业 | 10篇 |
无线电 | 3332篇 |
一般工业技术 | 9895篇 |
冶金工业 | 12180篇 |
原子能技术 | 369篇 |
自动化技术 | 6954篇 |
出版年
2023年 | 506篇 |
2022年 | 632篇 |
2021年 | 1183篇 |
2020年 | 840篇 |
2019年 | 870篇 |
2018年 | 1420篇 |
2017年 | 1250篇 |
2016年 | 1509篇 |
2015年 | 1328篇 |
2014年 | 1664篇 |
2013年 | 3169篇 |
2012年 | 2448篇 |
2011年 | 2808篇 |
2010年 | 2194篇 |
2009年 | 2101篇 |
2008年 | 2362篇 |
2007年 | 2252篇 |
2006年 | 1768篇 |
2005年 | 1430篇 |
2004年 | 1227篇 |
2003年 | 1124篇 |
2002年 | 986篇 |
2001年 | 792篇 |
2000年 | 701篇 |
1999年 | 871篇 |
1998年 | 3148篇 |
1997年 | 2011篇 |
1996年 | 1463篇 |
1995年 | 1030篇 |
1994年 | 886篇 |
1993年 | 815篇 |
1992年 | 458篇 |
1991年 | 389篇 |
1990年 | 440篇 |
1989年 | 427篇 |
1988年 | 380篇 |
1987年 | 401篇 |
1986年 | 376篇 |
1985年 | 504篇 |
1984年 | 434篇 |
1983年 | 403篇 |
1982年 | 347篇 |
1981年 | 382篇 |
1980年 | 363篇 |
1979年 | 323篇 |
1978年 | 275篇 |
1977年 | 417篇 |
1976年 | 729篇 |
1975年 | 252篇 |
1973年 | 229篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
32.
In this study, the effects of the phosphonic acid based sequestering agent EDTMPA used in the textile dye baths on colour and organic matter removal by ozone oxidation was experimentally investigated. Procion Navy HEXL dyestuff that has been commonly used for the reactive dyeing of cellulose fibers was selected as the model component. The organic matter oxidation by ozone was determined to obey the pseudo-first order kinetics as they are treated singly or in combination. COD removal rates obtained from pseudo-first order reaction kinetics showed that oxidation of Navy HEXL alone (0.0947 L/min) was faster than that of EDTMPA (0.0171 L/min) and EDTMPA with dye (0.0155 L/min) at pH 3.0. It was also found that reaction rates of single EDTMPA removal and EDTMPA and dye mixture removal increased as the reaction pH was increased from 3.0 to 10.5. 相似文献
33.
Joshua Vaughan Joel Fortgang William Singhose Jeffrey Donnell Thomas Kurfess 《Mechatronics》2008,18(4):179-186
It is commonly accepted that hands-on experiences increase both learning and enjoyment during coursework. Mechatronics projects provide both interesting and relevant hands-on experiences for a wide range of topics including design processes, basic mechatronics concepts, technical communication, and working in a group environment. ME2110: Creative Decisions and Design at Georgia Tech integrates mechatronics and technical communication into a sophomore level mechanical design class. This paper describes the course in detail, highlighting the course goals and layout, tools provided to the students, industry involvement, and the main challenges of administering such a course. 相似文献
34.
Ohne Zusammenfassung 相似文献
35.
Amit Chourasia Steve Cutchin Yifeng Cui Reagan W Moore Kim Olsen Steven M Day J Bernard Minster Philip Maechling Thomas H Jordan 《Computer Graphics and Applications, IEEE》2007,27(5):28-34
This study focuses on the visualization of a series of large earthquake simulations collectively called TeraShake. The simulation series aims to assess the impact of San Andreas Fault earthquake scenarios in Southern California. We discuss the role of visualization in gaining scientific insight and aiding unexpected discoveries. 相似文献
36.
F Wimmer J Lanschützer H Resch A Andretsch H Lempradl H Thöne K Mörwald J Kieweg H P Narzt CFürst 《钢铁》2004,39(Z1):590-592
1前言及历史背景
为避免钢水造成燃烧或破碎引起对人体的可能伤害,必须对连铸平台的平面布置进行分析. 相似文献
37.
This paper presents the current understanding of the flame retardant mechanism of Casico?. The study includes the flame retardant effect of each individual component: ethylene–acrylate copolymer, chalk and silicone elastomer, as well as the formation of an intumescent structure during heating. The flame retardant properties were investigated by cone calorimetry and oxygen index tests. To obtain insight into the flame retardant mechanism, heat treatment under different conditions has also been performed. The results indicate that the flame retardant mechanism of Casico is complex and is related to a number of reactions, e.g. ester pyrolysis of acrylate groups, formation of carbon dioxide by reaction between carboxylic acid and chalk, ionomer formation and formation of an intumescent structure stabilized by a protecting char. Special emphasis is given to the formation of the intumescent structure and its molecular structure as evaluated from 13C MAS‐NMR and 29Si MAS‐NMR, ESCA and XRD analysis. After treatment at 500°C the intumescent structure consists mainly of silicon oxides and calcium carbonate and after treatment at 1000°C the intumescent structure consists of calcium silicate, calcium oxide and calcium hydroxide. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
38.
Choosing a standard speed for visual inspection is difficult using standard work measurement techniques. This paper uses a different approach, taking a model of human functioning in inspection and deriving an optimum speed of working so as to balance the cost of time against the cost of errors. Random search is used as the model and both self-paced and externally-paced conditions are derived for multiple fault types. Optimization using a Golden Section search is used to provide optimum inspection speed. 相似文献
39.
J. Gegner Priv.‐Doz. Dr. W. Nierlich M. Brückner 《Materialwissenschaft und Werkstofftechnik》2007,38(8):613-623
Due to clearly distinguishable damage symptoms, it is differentiated between the surface and sub‐surface failure mode of rolling bearings. Material states red out by X‐ray diffraction (XRD) residual stress measurements point to a variety of loading conditions especially at raceway surfaces that are associated with several competing failure mechanisms. The corresponding lifetime reduction can range from the lower fatigue strength region to material ratcheting in extreme cases. Relevant position of the microstructural changes and nature of the failure mechanisms are characterized. The time alteration of the XRD material parameters measured at or near the surface and at the depth of the maximum equivalent stress correlates, in a different manner, with the statistical parameter of the 10 % bearing life. Both failure modes are illustrated by concrete examples. Contaminated lubricant and boundary lubrication, which represent practically important surface‐induced failures, are discussed in more detail. Gray staining, i.e. shallow pitting, often occurs without distinct indication of global material aging by means of XRD characteristics. Here, scanning electron microscopy observations and electron microprobe analyses point to corrosion fatigue as acting surface failure mechanism. The interaction between material and lubricant under complex loading regimes particularly of mixed friction and corrosion opens further failure research areas in the field of tribology. 相似文献
40.