全文获取类型
收费全文 | 261567篇 |
免费 | 20342篇 |
国内免费 | 13278篇 |
专业分类
电工技术 | 16731篇 |
技术理论 | 51篇 |
综合类 | 36246篇 |
化学工业 | 28860篇 |
金属工艺 | 9666篇 |
机械仪表 | 14066篇 |
建筑科学 | 37355篇 |
矿业工程 | 14866篇 |
能源动力 | 7846篇 |
轻工业 | 15038篇 |
水利工程 | 13900篇 |
石油天然气 | 11116篇 |
武器工业 | 2492篇 |
无线电 | 16834篇 |
一般工业技术 | 18346篇 |
冶金工业 | 15355篇 |
原子能技术 | 2626篇 |
自动化技术 | 33793篇 |
出版年
2024年 | 811篇 |
2023年 | 2494篇 |
2022年 | 4834篇 |
2021年 | 5791篇 |
2020年 | 6082篇 |
2019年 | 5123篇 |
2018年 | 4842篇 |
2017年 | 5823篇 |
2016年 | 7003篇 |
2015年 | 7837篇 |
2014年 | 14506篇 |
2013年 | 13185篇 |
2012年 | 17224篇 |
2011年 | 18330篇 |
2010年 | 14620篇 |
2009年 | 15243篇 |
2008年 | 14241篇 |
2007年 | 18730篇 |
2006年 | 17807篇 |
2005年 | 15573篇 |
2004年 | 13280篇 |
2003年 | 11970篇 |
2002年 | 9862篇 |
2001年 | 8353篇 |
2000年 | 7055篇 |
1999年 | 5761篇 |
1998年 | 4359篇 |
1997年 | 3819篇 |
1996年 | 3538篇 |
1995年 | 3002篇 |
1994年 | 2679篇 |
1993年 | 2011篇 |
1992年 | 1787篇 |
1991年 | 1331篇 |
1990年 | 1161篇 |
1989年 | 1023篇 |
1988年 | 820篇 |
1987年 | 566篇 |
1986年 | 430篇 |
1985年 | 352篇 |
1984年 | 332篇 |
1983年 | 240篇 |
1982年 | 214篇 |
1981年 | 166篇 |
1980年 | 131篇 |
1979年 | 110篇 |
1978年 | 62篇 |
1977年 | 72篇 |
1976年 | 55篇 |
1975年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
针对高强度船板纵裂纹轧后退废过高的现状,分析原因并优化冶炼、连铸工艺及操作,有效地降低高强度船板的退废率。 相似文献
993.
We present a new post processing method of simulating depth of field based on accurate calculations of circles of confusion. Compared to previous work, our method derives actual scene depth information directly from the existing depth buffer, requires no specialized rendering passes, and allows easy integration into existing rendering applications. Our implementation uses an adaptive, two‐pass filter, producing a high quality depth of field effect that can be executed entirely on the GPU, taking advantage of the parallelism of modern graphics cards and permitting real time performance when applied to large numbers of pixels. 相似文献
994.
铜冶炼系统节能降耗与余热利用前景分析 总被引:2,自引:0,他引:2
大规模铜冶炼系统的技术改造,可在短期内改变铜厂的面貌,快速提升产品产量,大幅降低铜冶炼的能耗,如何能更深层次地利用好余热资源,是我们研究和发展的方向。 相似文献
995.
《Information Systems Management》2007,24(2):113-120
Four scenarios for the IS organization of 2020 are described, based on differing assumptions about two drivers: the advances in the reliability of international telecommunications and the value placed on computerization in businesses and society. 相似文献
996.
简单分析了高炉煤气中Cl元素的存在对不锈钢膨胀节的应力腐蚀问题和防止途径,作为一种临时性的防范措施,简要介绍了煤气膨胀节包焊实施步骤和措施。 相似文献
997.
The authors of this paper investigated the influence of esters of rapeseed oil fatty acids on the lubricating properties of
mineral lubricants containing chosen AW/EP additives. Methyl esters, ethylene glycol esters, and glycerol esters as well as
some commercial AW/EP packages based on zinc dialkyldithiophosphate, S–P organic compounds, and sulphurized esters of fatty
acids were tested. The tribological tests were carried out with the use of a four-ball machine. Antiwear (AW) properties of
tested compositions were determined using their limiting load of wear (Goz(40)). It appears that the AW action of esters of rapeseed oil fatty acids depends on their structure. The best AW action is shown
by compositions of mineral oil lubricants containing AW/EP additives and methyl esters of rapeseed oil fatty acids. The SEM/EDS
analysis of the scar surface layer indicated that the presence of these esters in lubricants causes a change in the interaction
between AW/EP additives and the metal surface. These observations were confirmed by the XPS surface analysis. 相似文献
998.
针对750m^3高炉铁水生产富余状况,制订了富余铁水向铸铁机铸铁的调送方案,通过创新思维、系统挖潜、优化资源配置等措施的实施,保证了750m^3高炉的正常生产,取得了良好效果。 相似文献
999.
C. Llopis F. Revents L. Batet C. Pretel I. Sol 《Nuclear Engineering and Design》2007,237(18):2014-2023
The Technical University of Catalonia (UPC) has been jointly working with the Asociación Nuclear Ascó-Vandellòs (ANAV) for a number of years in order to establish, qualify and use best estimate (BE) models for the reactors under the control of ANAV. ANAV is the consortium that is responsible for operation of the Ascó and Vandellòs-II reactors. The reactors are Westinghouse-design three-loop PWRs with an approximate electrical power of 1000 MW. The existing integral plant models for each plant are currently used for many different purposes among which are support of plant operation and control. Quite a number of studies have been done in order to improve both safety and plant competitiveness. Most of these dynamic analyses were carried out in relation to transients starting at nominal full power or at least, very close to full power. This paper develops a specific use of the Vandellòs-II plant model for operation and control support at low power involving new ranges of system actuation parameters. It also examines scenarios that are somewhat different from those typically analysed. The study starts showing the results of an assessment case, which is a start-up test and provides some additional qualification, and subsequently attempts to establish calculations to support both an improvement in feed water controls and to set up operating recommendations for low-load manual operation of feed water turbo-pump. Both results hopefully, will produce an outcome, which leads to an improvement in safety and reduces reactor trip probability. 相似文献
1000.
A comparative analysis of such methods of defuzzification of fuzzy numbers as WABL (Weighted Averaging Based on Levels), centroid, and mean of maxima (MOM) is presented in the study. Analytic formulas are presented for calculating the defuzzification values for parametrically represented fuzzy numbers of triangular and trapezoidal form. 相似文献