全文获取类型
收费全文 | 465548篇 |
免费 | 7895篇 |
国内免费 | 2372篇 |
专业分类
电工技术 | 9221篇 |
技术理论 | 5篇 |
综合类 | 1302篇 |
化学工业 | 71035篇 |
金属工艺 | 17862篇 |
机械仪表 | 13024篇 |
建筑科学 | 11054篇 |
矿业工程 | 2361篇 |
能源动力 | 10266篇 |
轻工业 | 42747篇 |
水利工程 | 4674篇 |
石油天然气 | 8356篇 |
武器工业 | 262篇 |
无线电 | 52861篇 |
一般工业技术 | 86644篇 |
冶金工业 | 96513篇 |
原子能技术 | 8666篇 |
自动化技术 | 38962篇 |
出版年
2021年 | 4334篇 |
2020年 | 3218篇 |
2019年 | 4033篇 |
2018年 | 6552篇 |
2017年 | 6452篇 |
2016年 | 6914篇 |
2015年 | 5157篇 |
2014年 | 7985篇 |
2013年 | 20959篇 |
2012年 | 13339篇 |
2011年 | 17025篇 |
2010年 | 13709篇 |
2009年 | 14903篇 |
2008年 | 15900篇 |
2007年 | 15941篇 |
2006年 | 14047篇 |
2005年 | 12613篇 |
2004年 | 11802篇 |
2003年 | 11199篇 |
2002年 | 10967篇 |
2001年 | 11221篇 |
2000年 | 10487篇 |
1999年 | 11058篇 |
1998年 | 29398篇 |
1997年 | 20367篇 |
1996年 | 15446篇 |
1995年 | 11309篇 |
1994年 | 10023篇 |
1993年 | 10029篇 |
1992年 | 7080篇 |
1991年 | 6739篇 |
1990年 | 6694篇 |
1989年 | 6503篇 |
1988年 | 6075篇 |
1987年 | 5098篇 |
1986年 | 5192篇 |
1985年 | 5815篇 |
1984年 | 5418篇 |
1983年 | 4913篇 |
1982年 | 4474篇 |
1981年 | 4827篇 |
1980年 | 4336篇 |
1979年 | 4311篇 |
1978年 | 4205篇 |
1977年 | 4884篇 |
1976年 | 6661篇 |
1975年 | 3697篇 |
1974年 | 3512篇 |
1973年 | 3478篇 |
1972年 | 2958篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Sol–gel films are actively investigated during the last decade as possible candidates for environmentally friendly pre-treatments. However, the important drawback in this case is the lack of active corrosion protection and self-healing ability. 相似文献
102.
I. Revilla & M. L. González-San José 《International Journal of Food Science & Technology》2003,38(1):29-36
Summary The effect of the addition of four commercial pectolytic preparations on the visual characteristics (colour and turbidity) of red wines has been evaluated. The effect of both clarifying and colour extracting enzymes and the effect of different doses used, were evaluated and compared. All the red wines treated enzymatically, independent of the type of enzyme and dose, present chromatic characteristics which can be considered better than those of the control wines. Also, those wines treated with enzymes had greater stability during 2 years storage in bottles, in particular the turbidity was better than untreated wines. 相似文献
103.
The cooling and solidification of melted drops during their movement in an immiscible cooling medium is widely employed for granulation in the chemical industry, and a study of these processes to provides a basis for the design of the granulation tower height and the temperature of the cooling medium is reported. A physical model of the cooling and solidification of the drop is established and the numerical calculation is performed. The influences of the key factors in the solidification, i.e., Bi number, drop diameter, temperature of the cooling medium, etc. are presented. The cooling and solidification during wax granulation in a water‐cooling tower and during urea granulation in an air‐cooling tower (spraying tower) are described in detail. Characteristics of the solidification and temperature distribution within the particle at different times are shown. The model and calculations can be used for structure design of the granulation tower and optimization of the operation parameters. 相似文献
104.
A. T. Joseph 《Expert Systems》1991,8(2):119-127
ProKappa is an expert system tool kit developed by IntelliCorp in C using X-Windows for graphical interface. The SUN 3 or 4 version costs $9995/£7000 and $2595/£1800 for the interactive C environment.
This review covers ProKappa version 1.1, installed on a colour SUN SPARC Station 1 with the minimum recommended values of 12 Mb of memory and 30 Mb of swap space.
IntelliCorp can be contacted in the USA at 1975 El Camino Real West, Mountain View, CA 94040-2216 (+1 (415) 965-5500) and in the UK at 10 Jewry Street, Winchester, Hampshire SO23 8RZ (+44 (0)962 735348). 相似文献
This review covers ProKappa version 1.1, installed on a colour SUN SPARC Station 1 with the minimum recommended values of 12 Mb of memory and 30 Mb of swap space.
IntelliCorp can be contacted in the USA at 1975 El Camino Real West, Mountain View, CA 94040-2216 (+1 (415) 965-5500) and in the UK at 10 Jewry Street, Winchester, Hampshire SO23 8RZ (+44 (0)962 735348). 相似文献
105.
106.
107.
The benefits of adhesively bonded structures are well known. However, the most significant factor limiting the extensive application of metal bonding in primary aerospace structures is the prevailing lack of confidence in its long term durability under hostile environmental conditions.1,2 相似文献
108.
The graft copolymerization of methyl methacrylate onto natural rubber (NR) was carried out varying the concentration of monomer, initiator, thiourea, and silver nitrate over a wide range. The grafting reaction was temperature-dependent. From the Arrhenius plot, the overall energy of activation was computed. A suitable reaction scheme and rate expression for the rate of polymerization was suggested. 相似文献
109.
J. T. DICKINSON L. C. JENSEN W. DAVID WILLIAMS 《Journal of the American Ceramic Society》1985,68(5):235-240
We present measurements of the electron, positive ion, and photon emission accompanying the fracture in vacuum of poly-crystalline 95/5 lead zirconate-titanate. The intensities of the charged-particle components of this fractoemission are shown to depend strongly on the direction (relative to the direction of fracture) and magnitude of polarization. The most intense emission is observed when the fracture surfaces are perpendicular to the polarization direction. The emission intensity increases monotonically with polarization. These results are interpreted in terms of a model involving charge separation on the fracture surfaces leading to a microdischarge during fracture. Implications to the interpretation of triboluminesence effects are discussed. 相似文献
110.
D. A. Morgan D. B. Shaw M. J. Sidebottom T. C. Soon R. S. Taylor 《Journal of the American Oil Chemists' Society》1985,62(2):292-299
The results presented in the literature, which attempt to elucidate the mechanisms by which triglyceride oils are bleached
by earths, are reviewed. The impact of this work and how the mechanistic proposals affect changes in oil properties are considered,
with particular emphasis on the needs of the palm oil processor. Important properties include color, metals and phosphorus
content and oxidative stability of the oil.
Investigations made in our own laboratories have been aimed at elucidating the effect of varying physical and chemical properties
of the bleaching earth on the quality of bleached and deodorized oils. Techniques used in this work are pore-size distribution,
surface area, scanning and transmission electron microscopy and a variety of chemical and X-ray analysis methods.
The ability to vary such parameters in montmorillonite clays by alteration of process conditions to give materials with specific
performance characteristics is demonstrated.
Comparisons are made between acid-activated montmorillonites and other clay types. 相似文献