全文获取类型
收费全文 | 4799篇 |
免费 | 415篇 |
国内免费 | 184篇 |
专业分类
电工技术 | 148篇 |
技术理论 | 1篇 |
综合类 | 175篇 |
化学工业 | 251篇 |
金属工艺 | 91篇 |
机械仪表 | 228篇 |
建筑科学 | 2118篇 |
矿业工程 | 60篇 |
能源动力 | 149篇 |
轻工业 | 135篇 |
水利工程 | 8篇 |
石油天然气 | 12篇 |
武器工业 | 96篇 |
无线电 | 431篇 |
一般工业技术 | 358篇 |
冶金工业 | 129篇 |
原子能技术 | 67篇 |
自动化技术 | 941篇 |
出版年
2024年 | 6篇 |
2023年 | 71篇 |
2022年 | 71篇 |
2021年 | 97篇 |
2020年 | 114篇 |
2019年 | 73篇 |
2018年 | 75篇 |
2017年 | 83篇 |
2016年 | 198篇 |
2015年 | 149篇 |
2014年 | 315篇 |
2013年 | 266篇 |
2012年 | 334篇 |
2011年 | 342篇 |
2010年 | 323篇 |
2009年 | 318篇 |
2008年 | 325篇 |
2007年 | 339篇 |
2006年 | 331篇 |
2005年 | 267篇 |
2004年 | 195篇 |
2003年 | 178篇 |
2002年 | 150篇 |
2001年 | 113篇 |
2000年 | 88篇 |
1999年 | 104篇 |
1998年 | 69篇 |
1997年 | 63篇 |
1996年 | 46篇 |
1995年 | 36篇 |
1994年 | 54篇 |
1993年 | 25篇 |
1992年 | 40篇 |
1991年 | 32篇 |
1990年 | 27篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有5398条查询结果,搜索用时 140 毫秒
1.
本文开发了一种新型的方舱夹芯板用室温固化高强度环氧结构胶黏剂,验证了其物化特性、相关力学性能和环境适应性。结果表明此胶黏剂具有优良性能,可以满足方舱用大板胶黏剂的使用需求。 相似文献
2.
Ahlam Ammar Sharif 《建筑学研究前沿(英文版)》2020,9(4):837-857
Urban researchers have maintained a constant interest in the complexity and continuity of urban space usage. Some have applied actor–network theory (ANT) to investigate the heterogeneity of spaces and present them through the networks of their users’ activities. However, these accounts are predominantly limited in examining the extent to which these spaces may be heterogeneous when exploring such networks. This paper draws on recent ANT scholarship, which employs an ethnographic research conducted in a main park in a housing project at Dahiyat Al Hussein in Amman, Jordan. The findings describe the complex and unpredictable negotiations that occur within spaces by documenting the varieties and interrelations among user activity networks within this common and shared urban space. This research reveals the extent to which spaces, parks in this case, may be heterogeneous by unpacking their usage. The conclusions and insights assert the necessity of paying attention to design detail and creating designs that are responsive to evolving user activities. 相似文献
3.
本文探讨了系统级简化形式的电磁兼容性预测分析方法,该方法对于只有几对发-收干扰对的系统EMI的预测分析简洁有效,它避免了大系统间繁复的建模与大量的数据采集及其计算工作,从而对于只考虑其结果的系统间的EMC预测分析提高了效率。 相似文献
4.
J.S. Sánchez 《Pattern recognition》2004,37(7):1561-1564
Instance-based learning methods like the nearest neighbour classifier generally suffer from the indiscriminate storage of all training instances, resulting in large memory requirements and slow execution speed. In this paper, new training set size reduction methods based on prototype generation and space partitioning are proposed. Experimental results show that the new algorithms achieve a very high reduction rate with still an important classification accuracy. 相似文献
5.
Yong-Jik KimJames H. Anderson 《Information Processing Letters》2002,84(1):47-55
A simple code transformation is presented that reduces the space complexity of Yang and Anderson's local-spin mutual exclusion algorithm. In both the original and the transformed algorithm, only atomic read and write instructions are used; each process generates Θ(logN) remote memory references per lock request, where N is the number of processes. The transformed algorithm uses Θ(N) distinct variables, which is clearly optimal. 相似文献
6.
7.
为了研究带电粒子光学系统的光学特性,需要知道系统中磁场的空间分布。实际磁场往往不具有严格的平面对称性质,一些作者曾就这类磁场的空间展开做过不少工作。但他们的工作是在柱坐标系统中进行的,适用于诸如回旋加速器、双向聚焦磁分析器、环形磁β谱仪等一类装置的磁场分析。对于大型同位素电磁分离器(calutron)那样一类装置,其磁场分布需要 相似文献
8.
A. S. S. R. Reddy 《Canadian Metallurgical Quarterly》1992,5(1):70-78
The dynamic analysis and control system design of large space structures involve the solution of the large‐dimensional generalized matrix eigenvalue problem. The computational effort involved is proportional to the third power of the dimension of the matrices involved. To minimize the computational time a graph‐theory approach to reduce a matrix to lower‐ordered submatrices is proposed. The matrix‐reduction algorithm uses the Boolean matrices corresponding to the original numerical matrices and, thus, the computational effort to reduce the original matrix is nominal. The computational savings directly depend upon the number of submatrices into which the original matrix is reduced. A free‐free square plate is considered as an example to illustrate the technique. In this example a matrix of 16th order is reduced to three scalars corresponding to three rigid‐body modes, and three matrices of order three and one matrix of order four. 相似文献
9.
TiAl+Sb合金的热稳定性的研究 总被引:1,自引:0,他引:1
研究了退火处理对Ti-34wt.%Al-0.5wt.%Sb合金的室温抗弯性能,显微组织,相组成和断口形貌的影响。发现,低于1000℃退火处理,TiAl+Sb合金的显微组织没有变化,其力学性能仍然保持较高的值。此合金成分适应高温使用条件。 相似文献
10.
Bülent M. Ba?ol Vijay K. Kapur Craig R. Leidholm Arvind Halani Kristen Gledhill 《Solar Energy Materials & Solar Cells》1996,43(1):93
Thin film flexible CuInSe2 (CIS) solar cells have been fabricated for the first time on light-weight polymeric substrates. Evaporated Cu---In alloy precursors were selenized in H2Se atmosphere at around 400°C to grow the CIS absorber layers. Low temperature techniques which are compatible with the polymeric substrates were used to deposit the window layers of CdS and ZnO. The demonstrated active area conversion efficiency of 9.3% makes this light-weight device very attractive for many terrestrial and space power generation applications where high specific power and mechanical flexibility are needed. 相似文献