全文获取类型
收费全文 | 3658篇 |
免费 | 62篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 92篇 |
综合类 | 9篇 |
化学工业 | 719篇 |
金属工艺 | 131篇 |
机械仪表 | 82篇 |
建筑科学 | 44篇 |
矿业工程 | 1篇 |
能源动力 | 191篇 |
轻工业 | 162篇 |
水利工程 | 41篇 |
石油天然气 | 18篇 |
无线电 | 440篇 |
一般工业技术 | 858篇 |
冶金工业 | 371篇 |
原子能技术 | 22篇 |
自动化技术 | 551篇 |
出版年
2024年 | 50篇 |
2023年 | 56篇 |
2022年 | 106篇 |
2021年 | 126篇 |
2020年 | 114篇 |
2019年 | 105篇 |
2018年 | 120篇 |
2017年 | 131篇 |
2016年 | 133篇 |
2015年 | 72篇 |
2014年 | 136篇 |
2013年 | 242篇 |
2012年 | 148篇 |
2011年 | 191篇 |
2010年 | 167篇 |
2009年 | 172篇 |
2008年 | 114篇 |
2007年 | 115篇 |
2006年 | 93篇 |
2005年 | 76篇 |
2004年 | 66篇 |
2003年 | 83篇 |
2002年 | 70篇 |
2001年 | 58篇 |
2000年 | 53篇 |
1999年 | 46篇 |
1998年 | 80篇 |
1997年 | 74篇 |
1996年 | 50篇 |
1995年 | 50篇 |
1994年 | 52篇 |
1993年 | 48篇 |
1992年 | 33篇 |
1991年 | 36篇 |
1990年 | 28篇 |
1989年 | 30篇 |
1988年 | 32篇 |
1987年 | 39篇 |
1986年 | 19篇 |
1985年 | 39篇 |
1984年 | 33篇 |
1983年 | 24篇 |
1982年 | 25篇 |
1981年 | 22篇 |
1980年 | 28篇 |
1979年 | 17篇 |
1977年 | 21篇 |
1976年 | 27篇 |
1975年 | 11篇 |
1973年 | 17篇 |
排序方式: 共有3732条查询结果,搜索用时 0 毫秒
71.
In this paper, the relationship between the number of unit-cells used in the design of a frequency selective surface (FSS) and its expected directivity is established. The relationship between the number of FSS unit-cells and the directivity is based on the planer microstrip patch array antenna design concept where the unit-cell is treated as the superstrate illuminated by the source. To validate the proposed technique, the analytical value of the directivity has been compared with that of ray-tracing method. The directivity of antenna is calculated for two different planar array configurations at 600 GHz. The results of numerical analysis are compared to that of the full-wave electromagnetic simulator CST Microwave Studio and results are comparable. Further, the directivity computed by this proposed technique has also been compared with that of the reported in literatures. 相似文献
72.
Treatment of 6-O-p-tolylsulfonyl starch with anhydrous potassium fluoride in boiling 1,2-dihydroxyethane afforded deoxyfluorostarches (D. S. Fluorine 0.18). Reaction of starch with hydrofluoric acid in dimethyl sulfoxide at −30 °C gave deoxyfluorostarches of high fluorine content (D. S. Fluorine 0.91). Chlorodeoxystarches have been prepared by the reaction of corn starch with (chloromethylene) dimethylimminium chloride in N, N′-dimethyl-formamide. 相似文献
73.
Different synthetic products currently available and which find wide application as lubricants, are described, and their merits and demerits compared with the mineral based lubricants are outlined. Some of the major synthetic lubricants used in Indian industries are identified. The Indian chemical industry's potential to meet some of the requirements of synthetic lubricants is discussed and the need to create additional facilities in India for the manufacture of certain critical products, is described. 相似文献
74.
P. L. Soni H. W. Sharma S. S. Bisen H. C. Srivastava M. M. Gharia 《Starch - St?rke》1987,39(12):411-413
Starch from sal seeds cake was isolated, bleached and purified. Scanning electron microscopy of the starch showed round to oval shaped granules of the size 3.5 to 12.3 μm. The starch has more nitrogen, phosphorus, lipids, amylose and water binding capacity in comparison to the other starches of forest origin. Despite its low and seemingly restricted swelling, the sal starch is much more soluble at any particular degree of swelling. Paste viscosity curve showed no drop in viscosity after full gelatinisation had taken place, i. e. the paste is stable on continued cooking. 相似文献
75.
Maurya Ranjan Kumar Kaur Rajvinder Kumar Ramesh Agarwal Ajay 《Microsystem Technologies》2019,25(10):3933-3941
Microsystem Technologies - This paper reports the development of a novel electronic micro-viscometer capable of measuring viscosity of different Newtonian fluids using less than 100 µl which... 相似文献
76.
Das Swarup Chattopadhyay Krishnendu Bhadra Chaudhuri Sekhar Ranjan 《Wireless Personal Communications》2020,110(2):677-698
Wireless Personal Communications - In this paper a combination of rectangular and elliptical fractal geometry is applied on a regular hexagonal wide slot antenna fabricated using a FR4 substrate to... 相似文献
77.
Rakesh Sarin Ajay K. Arora Rajeev Ranjan Anurag A. Gupta Ravinder K. Malhotra 《Lubrication Science》2007,19(2):151-157
Bio‐diesel has been accepted as a renewable liquid biofuel worldwide. In order to ensure customers' acceptance, standardisation and quality assurance are the key factors to the market introduction of bio‐diesel as a transport fuel. Lubricity of bio‐diesel is an important issue and it is well reported that 1–2% bio‐diesel is sufficient to maintain the lubricity of diesel even of very poor lubricity. However, a wide variation in lubricity performance of bio‐diesel from different vegetable oils and sources has been noticed. In addition, on critical examination, it was noticed that the variation in the lubricating performance of bio‐diesel could be better linked to its residual acidity than to variation in fatty acid composition. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
78.
Practical application of aligned carbon nanotubes (ACNTs) would have to be determined by a matter of its economical and large-scale
preparation. In this study, neem oil (also named Margoaa oil, extracted from the seeds of the neem--Azadirachta indica) was used as carbon source to fabricate the bundles of ACNTs. ACNTs have been synthesized by spray pyrolysis of neem oil
and ferrocene mixture at 825°C. The major components of neem oil are hydrocarbon with less amount of oxygen, which provided
the precursor species in spray pyrolysis growth of CNTs. The bundles of ACNTs have been grown directly inside the quartz tube.
The as-grown ACNTs have been characterized through Raman spectroscopy, scanning and transmission electron microscopic (SEM/TEM)
techniques. SEM images reveal that the bundles of ACNTs are densely packed and are of several microns in length. High-resolution
TEM analysis reveals these nanotubes to be multi-walled CNTs. These multi-walled CNTs were found to have inner diameter between
15 and 30 nm. It was found that present technique gives high yield with high density of bundles of ACNTs. 相似文献
79.
Rajiv Budbraja 《中国橡胶》2011,(8):11-14
1.Global Vehicle Sales From 2007 to 201 1,only two countries have recorded a doubling of their respective percentage share in global vehicle sales growth in 4 years:INDIA(2%to 4%) & CHINA(11%to 24%). While India & China have maintained similar growth trends(in%) in absolute numbers,there is a significant difference. China overshadows India's performance/growth in vehicle 相似文献
80.
Chandrasekar Saravanan Srinivasan Palaniappan Valaboju Akhila Sunkara Sakunthala Madhavendra Prakriti Ranjan Bangal 《应用聚合物科学杂志》2011,120(4):2421-2427
Sulfonated‐p‐cresol (SPC) was used as novel dopant for the first time in the synthesis of polyaniline in 3D nanofiber networks (PANI‐3D). Polyaniline in 3D nanofiber network was prepared using organic solvent soluble benzoyl peroxide as oxidizing agent in presence of SPC and sodium lauryl sulfate (SLS) surfactant via inverted emulsion polymerization pathway. The influence of synthesis conditions such as the concentration of the reactants, stirring/static condition, and temperature etc., on the properties and formation of polyaniline nanofiber network were investigated. Polyaniline in 3D nanofiber network with 40–160 nm (diameter), high yield (134 wt % with respect to aniline used), and reasonably good conductivity (0.1 S/cm) was obtained in 24 h time. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献