全文获取类型
收费全文 | 54229篇 |
免费 | 3503篇 |
国内免费 | 1830篇 |
专业分类
电工技术 | 1674篇 |
技术理论 | 4篇 |
综合类 | 3703篇 |
化学工业 | 12113篇 |
金属工艺 | 6714篇 |
机械仪表 | 1324篇 |
建筑科学 | 10210篇 |
矿业工程 | 2136篇 |
能源动力 | 1072篇 |
轻工业 | 4112篇 |
水利工程 | 2518篇 |
石油天然气 | 1726篇 |
武器工业 | 176篇 |
无线电 | 1039篇 |
一般工业技术 | 4038篇 |
冶金工业 | 5027篇 |
原子能技术 | 256篇 |
自动化技术 | 1720篇 |
出版年
2024年 | 187篇 |
2023年 | 618篇 |
2022年 | 1338篇 |
2021年 | 1635篇 |
2020年 | 1478篇 |
2019年 | 1043篇 |
2018年 | 1019篇 |
2017年 | 1289篇 |
2016年 | 1312篇 |
2015年 | 1548篇 |
2014年 | 3006篇 |
2013年 | 2727篇 |
2012年 | 3697篇 |
2011年 | 3983篇 |
2010年 | 3441篇 |
2009年 | 3609篇 |
2008年 | 2782篇 |
2007年 | 3756篇 |
2006年 | 3596篇 |
2005年 | 3065篇 |
2004年 | 2632篇 |
2003年 | 2370篇 |
2002年 | 1966篇 |
2001年 | 1518篇 |
2000年 | 1209篇 |
1999年 | 939篇 |
1998年 | 718篇 |
1997年 | 587篇 |
1996年 | 446篇 |
1995年 | 410篇 |
1994年 | 290篇 |
1993年 | 212篇 |
1992年 | 216篇 |
1991年 | 164篇 |
1990年 | 99篇 |
1989年 | 126篇 |
1988年 | 74篇 |
1987年 | 65篇 |
1986年 | 44篇 |
1985年 | 45篇 |
1984年 | 46篇 |
1983年 | 38篇 |
1982年 | 20篇 |
1980年 | 10篇 |
1966年 | 14篇 |
1965年 | 15篇 |
1964年 | 25篇 |
1963年 | 16篇 |
1961年 | 12篇 |
1959年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
112.
113.
采用正交试验对汽轮机叶片用X20Cr13钢进行了热处理工艺研究,以获得该钢的最佳热处理工艺,并在回火后以不同的速度冷却,以揭示冷却速度对钢的回火脆性的影响。结果,X20Cr13钢的最佳热处理工艺为900℃油淬或风冷,670℃回火,风冷。 相似文献
114.
115.
铜铬锆合金是一种形变热处理材料,兼具了铜铬合金和铜锆合金的各种优良性能,经过时效处理的铜铬锆合金,与铜相比,高温强度有很大的改善,而且具有较高的导电率。所以铜铬锆合金广泛应用于电焊机、低压电器等行业。根据对铜铬锆成分的适当调整,可用作为电焊机电极,低压电器触桥、短路环等各种电接触材料。铜铬锆合金用于RMT1-250转换开关,接近于触桥材料的应用,但使用的条件更苛刻一些,要承受部分电弧的侵蚀和由此产生的高温,因此对材料要求具有良好的导电导热性和更高的高温强度。 相似文献
116.
Self-control is demonstrated when a less desirable immediate outcome is chosen to ensure a substantially better future. In a novel animal analogue of this situation, primary reinforcement was delivered in both the initial and terminal links of a concurrent chain schedule. Rats made initial link choices between equal amounts of ethanol-free or ethanol-containing milk. Choosing the ethanol-free reinforcer resulted in delivery of the larger terminal link reinforcer and was thus analogous to self-control. Self-control decreased as the delay between initial and terminal links increased. The results have implications for human choice situations where decisions are made between two immediately available reinforcement alternatives each associated with a different delayed outcome. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
117.
LIJuan HUAYu-lin WANGChang-sheng XIONGShao-zhen 《半导体光子学与技术》2004,10(1):41-43,47
The white organic light emitting device (OLED) with single-structure using a polymer blend as the light emitting layer is fabricated. Heat treatment is used to control the ratio between the intensities of main electroluminescent spectral peaks. The electroluminescent spectrum of our device is quite similar to that of white inorganic LED produced by Nichia Corporation after being annealed, and its turn-on voltage can be decreased by 1V. 相似文献
118.
John E. Sohn 《The Journal of Adhesion》1985,19(1):15-27
Enhanced matrix-filler adhesion is realized after filler treatment with a surface treatment process. The hydrosol/coupling agent treatment was applied to a wide range of inorganic and organic fillers, and adhesion to a variety of matrix resins was improved. Scanning Electron Microscopy (SEM) was used to determine the locus of failure in the filled systems. The locus of failure shows the relative degree of adhesion between the filler and the polymer matrix. Significant improvement in adhesion in humid environments is also observed. 相似文献
119.
C. N. Haas B. F. Severin D. Roy R. S. Engelbrecht A. Lalchandani S. Farooq 《Water research》1985,19(3):323-329
This paper summarizes studies on the presence of acid-fast and yeast organisms in wastewater and water treatment plants and in surface water. These organisms were found to satisfy three of Bonde's criteria for indicator organisms: presence whenever pathogens are likely to be present; resistance at least equal to that of pathogens; and lack of regrowth in the post-treatment environment. This, plus prior data, indicates that these organisms are at least as acceptable as indicators of disinfection efficiency than the coliform group. 相似文献
120.
Utilizing data from the Riggs-Yale Project, 45 male and 45 female 18-29-year-old treatment-resistant inpatients undergoing intensive psychoanalytically oriented treatment were studied. Twenty-seven mixed-type anaclitic-introjective inpatients were compared with 29 "pure" anaclitic and 34 "pure" introjective inpatients. At intake, mixed-type inpatients were more clinically impaired (i.e., were more symptomatic, cognitively impaired, and thought disordered) and more vulnerable (i.e., less accurate object representations and more frequently used maladaptive defense mechanisms) in comparison with clearly defined anaclitic and introjective patients. Mixed-type patients, however, improved significantly more in the course of psychoanalytically oriented treatment, in terms of clinical functioning (i.e., symptoms, cognitive functioning) and psychological vulnerability (i.e., utilization of more adaptive defense mechanisms). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献