全文获取类型
收费全文 | 357405篇 |
免费 | 27952篇 |
国内免费 | 15721篇 |
专业分类
电工技术 | 20874篇 |
技术理论 | 45篇 |
综合类 | 25384篇 |
化学工业 | 59676篇 |
金属工艺 | 20812篇 |
机械仪表 | 22462篇 |
建筑科学 | 27636篇 |
矿业工程 | 11686篇 |
能源动力 | 9701篇 |
轻工业 | 24006篇 |
水利工程 | 6754篇 |
石油天然气 | 23437篇 |
武器工业 | 2798篇 |
无线电 | 38820篇 |
一般工业技术 | 39384篇 |
冶金工业 | 18533篇 |
原子能技术 | 3625篇 |
自动化技术 | 45445篇 |
出版年
2024年 | 1456篇 |
2023年 | 5563篇 |
2022年 | 9873篇 |
2021年 | 13883篇 |
2020年 | 10444篇 |
2019年 | 8545篇 |
2018年 | 9855篇 |
2017年 | 11083篇 |
2016年 | 10137篇 |
2015年 | 13876篇 |
2014年 | 17458篇 |
2013年 | 20906篇 |
2012年 | 22708篇 |
2011年 | 25183篇 |
2010年 | 22249篇 |
2009年 | 21075篇 |
2008年 | 20652篇 |
2007年 | 19702篇 |
2006年 | 20066篇 |
2005年 | 17659篇 |
2004年 | 11976篇 |
2003年 | 10693篇 |
2002年 | 9901篇 |
2001年 | 8815篇 |
2000年 | 8759篇 |
1999年 | 9389篇 |
1998年 | 7177篇 |
1997年 | 6139篇 |
1996年 | 5811篇 |
1995年 | 4786篇 |
1994年 | 3887篇 |
1993年 | 2622篇 |
1992年 | 2072篇 |
1991年 | 1569篇 |
1990年 | 1235篇 |
1989年 | 995篇 |
1988年 | 830篇 |
1987年 | 524篇 |
1986年 | 410篇 |
1985年 | 258篇 |
1984年 | 206篇 |
1983年 | 164篇 |
1982年 | 128篇 |
1981年 | 76篇 |
1980年 | 96篇 |
1979年 | 43篇 |
1978年 | 17篇 |
1977年 | 23篇 |
1976年 | 28篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
32.
33.
34.
前言 近20年来,随着改革开放和国民经济的飞速发展,我国建筑卫生陶瓷行业也得到快速发展,产量连年增长,成为世界上建筑卫生陶瓷的最大生产国和消费国,也是出口大国.2007年全国卫生陶瓷的产量达到15 000万件,占世界产量的40%,出口量达到5 525万件,占产量的40%. 相似文献
35.
李宏伟 《数值计算与计算机应用》2003,24(1):44-52
1.引 言 古典加法Schwarz方法(ASM)对于一般问题收敛很慢,在大多数情况下, ASM只能作为预条件子.另一方面,ASM的并行性能非常好,尤其适合大规模粗粒度并行计算,近年来随着并行机系统及并行计算的兴起,ASM重新受到重视.许多学者研究了怎样提高ASM的收敛速度[1,2,4].他们发现加法Schwarz方法之所以收敛慢是由于在内边界上采用 相似文献
36.
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
37.
Xiang‐Dan Li Zhen‐Xin Zhong Sang‐Hoon Han Seung Hee Lee Myong‐Hoon Lee 《Polymer International》2005,54(2):406-411
From chloromethylated polyimide, a useful starting material for modification of aromatic polyimides, a thermocurable transparent polyimide having acrylate side groups was prepared. In the presence of 1,8‐diazabicyclo[5,4,0]undec‐7‐ene, chloromethylated polyimide was esterified with acrylic acid to synthesize poly(imide methylene acrylate). The polymer was soluble in organic solvent, which makes it possible to prepare a planar film by spin coating. The polymer film became insoluble after thermal treatment at 230 °C for 30 min. Optical transparency of the film at 400 nm (for 1 µm thickness) was higher than 98 % and not affected by further heating at 230 °C for 250 min. Adhesion properties measured by the ASTM D3359‐B method ranged from 4B to 5B. Preliminary results of planarization testing showed a high degree of planarization (DOP) value (>0.53). These properties demonstrate that poly(imide methylene acrylate) could be utilized as a thermocurable transparent material in fabricating display devices such as TFT‐LCD. Copyright © 2004 Society of Chemical Industry 相似文献
38.
On the basis of the compensation of errors it is postulated that the most accurate correction may not always give the most accurate result for calorific value, and experimental evidence for this is presented. A new criterion is therefore suggested for judging the best (not necessarily the most accurate) cooling correction. Using this principle the cooling correction formula previously proposed is improved which results in higher accuracy whilst retaining the original simplicity. 相似文献
39.
本文介绍了一个用户接口管理系统NUUIMS的设计和实现.重点叙述了该系统基于规范化目标用户接口模型的设计思想,系统组成及描述方法.文章也讨论了使用NUUIMS设计而成的用户接口的特点. 相似文献
40.
Aimin Xiang Zhongjie Du Qinghua Zeng Chen Zhang Hangquan Li 《Polymer International》2005,54(10):1366-1370
This paper presents recent efforts on the preparation of flexible polyhedral particles via concentrated emulsion templating polymerization in which the hydrophilic monomer (acrylamide) and hydrophobic monomer (butyl acrylate) are polymerized simultaneously in the continuous and dispersed phase, respectively. Such templating polymerization has been enhanced in our systems owing to the introduction of acrylamide monomer and their higher polymerization rate in continuous phase as compared with butyl acrylate in dispersed phase. Diffusion between the different phases was also inhibited. Furthermore, the stability of the concentrated emulsion and the molecular weight of the produced poly(butyl acrylate) were found to be significantly affected by the amount of redox initiator. The morphology of the particles could be controlled by varying the volume fraction of the dispersed phase and the polyhedral particles were achieved at higher volume fraction. Copyright © 2005 Society of Chemical Industry 相似文献