全文获取类型
收费全文 | 485188篇 |
免费 | 4556篇 |
国内免费 | 1033篇 |
专业分类
电工技术 | 8304篇 |
综合类 | 252篇 |
化学工业 | 76861篇 |
金属工艺 | 23852篇 |
机械仪表 | 16563篇 |
建筑科学 | 10477篇 |
矿业工程 | 4792篇 |
能源动力 | 9995篇 |
轻工业 | 33874篇 |
水利工程 | 6455篇 |
石油天然气 | 16378篇 |
武器工业 | 36篇 |
无线电 | 47535篇 |
一般工业技术 | 106335篇 |
冶金工业 | 77188篇 |
原子能技术 | 15418篇 |
自动化技术 | 36462篇 |
出版年
2021年 | 4381篇 |
2019年 | 4174篇 |
2018年 | 8006篇 |
2017年 | 8169篇 |
2016年 | 8643篇 |
2015年 | 4961篇 |
2014年 | 8513篇 |
2013年 | 20393篇 |
2012年 | 12792篇 |
2011年 | 16473篇 |
2010年 | 13372篇 |
2009年 | 15116篇 |
2008年 | 15569篇 |
2007年 | 15126篇 |
2006年 | 12887篇 |
2005年 | 11759篇 |
2004年 | 11251篇 |
2003年 | 10825篇 |
2002年 | 10768篇 |
2001年 | 10450篇 |
2000年 | 10138篇 |
1999年 | 9641篇 |
1998年 | 20636篇 |
1997年 | 15769篇 |
1996年 | 12129篇 |
1995年 | 9514篇 |
1994年 | 8675篇 |
1993年 | 8764篇 |
1992年 | 7022篇 |
1991年 | 7035篇 |
1990年 | 7024篇 |
1989年 | 6891篇 |
1988年 | 6691篇 |
1987年 | 6099篇 |
1986年 | 5998篇 |
1985年 | 6733篇 |
1984年 | 6497篇 |
1983年 | 6071篇 |
1982年 | 5727篇 |
1981年 | 5888篇 |
1980年 | 5743篇 |
1979年 | 5896篇 |
1978年 | 6110篇 |
1977年 | 6579篇 |
1976年 | 8000篇 |
1975年 | 5547篇 |
1974年 | 5443篇 |
1973年 | 5553篇 |
1972年 | 4872篇 |
1971年 | 4480篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
992.
G. Anandalingam 《Energy Policy》1985,13(4):335-339
This paper begins by examining the most energy-intensive industries and methods by which fuel efficiency can be improved. Next the author analyses the economics of energy conservation using specific case studies drawn from India. It is shown that investing in energy efficiency is more economical Btu per Btu than investing in the enhancement of domestic energy resources. The author also assesses changes in the economics of conservation for private firms when there are government incentives. Finally government policies that can overcome economic and non-economic disincentives for investing in energy conservation are examined. 相似文献
993.
G. Kardaun 《Energy》1985,10(2):119-127
Worldwide demand and supply of natural gas may rise substantially between the years 1982 and 2000, but the rate of increase will decelerate after 1990. The rapid growth of potential demand in the first decade is expected to take place in the developing countries in particular. During this period, gas production potential will rise most rapidly in Eastern Europe (including the U.S.S.R.) and in the Third World countries of Latin America, Africa, the Middle East, and Asia. In the year which has passed since the Venice Conference, forecasts of future natural gas demand in Western Europe have been reduced from 300–350 × 109 m3 (in the year 2000) to 270 × 109 m3. This change has greatly diminished the expected need for gas imports into Western Europe. It has also had a positive effect on the reserve position, relative to anticipated demand, of the Netherlands, which now will consider making more gas available for Western European markets. 相似文献
994.
995.
996.
V. D. Belik R. V. Litvin M. S. Koval’chenko 《Powder Metallurgy and Metal Ceramics》2006,45(11-12):593-598
The influence exerted by electric-spark spraying on the kinetics of mass transfer and the physicomechanical properties of coatings is investigated. It is shown that electric-spark spraying is determined by the dynamic properties of the cathode jets, which depend on the electrical parameters of the spark discharge, the size of the interelectrode interval, and the physical properties of the coatings, which vary during spraying. 相似文献
997.
No longer satisfied with compromising and controlling individual computers, a new breed of hackers have set their sights on virtual networks of zombie systems, which they use in concert to accomplish various nefarious deeds. Beware the botnet. 相似文献
998.
The possibility of obtaining chemically stable ceramics in plastic molding from pastes based on comprehensive use of mining
by-products (plagioporphyry, quartz-biotite shale), alumina production wastes (red mud), and polymineral clay was demonstrated.
The mechanism of enhancing paste sintering on addition of finely disperse grog-flux and increasing the alkali resistance of
the material (to 95%) in molding of the crystalline hematite-anorthite-quartz system was examined.
__________
Translated from Steklo i Keramika, No. 2, pp. 17–20, February, 2007. 相似文献
999.
1000.
I N Trubachev Iu N Okladnikov V A Barashkov G S Kalacheva N A Tabakov 《Voprosy pitaniia》1985,(1):55-57
The authors studied the biochemical composition of the meat of broilers, eggs, liver and muscles of laying hens of 3 generations on a 5, 10, 25, 50 and 100% (broilers), 10 and 20% (laying hens) replacement of the animal protein quota in the diet by protein obtained from the hydrogen bacteria Alcaligenes eutrophus L-1. No deterioration of the quality of the produce was found from the standpoint of the main biochemical parameters. 相似文献