全文获取类型
收费全文 | 116430篇 |
免费 | 9064篇 |
国内免费 | 4749篇 |
专业分类
电工技术 | 6345篇 |
技术理论 | 12篇 |
综合类 | 7160篇 |
化学工业 | 19933篇 |
金属工艺 | 6660篇 |
机械仪表 | 7069篇 |
建筑科学 | 9145篇 |
矿业工程 | 3569篇 |
能源动力 | 3487篇 |
轻工业 | 7679篇 |
水利工程 | 2011篇 |
石油天然气 | 8135篇 |
武器工业 | 831篇 |
无线电 | 12674篇 |
一般工业技术 | 14201篇 |
冶金工业 | 6056篇 |
原子能技术 | 1354篇 |
自动化技术 | 13922篇 |
出版年
2024年 | 455篇 |
2023年 | 1857篇 |
2022年 | 3260篇 |
2021年 | 4637篇 |
2020年 | 3503篇 |
2019年 | 3003篇 |
2018年 | 3456篇 |
2017年 | 3814篇 |
2016年 | 3443篇 |
2015年 | 4384篇 |
2014年 | 5808篇 |
2013年 | 6683篇 |
2012年 | 7280篇 |
2011年 | 7904篇 |
2010年 | 6991篇 |
2009年 | 6454篇 |
2008年 | 6325篇 |
2007年 | 6166篇 |
2006年 | 6366篇 |
2005年 | 5491篇 |
2004年 | 3603篇 |
2003年 | 3180篇 |
2002年 | 2898篇 |
2001年 | 2573篇 |
2000年 | 2823篇 |
1999年 | 3210篇 |
1998年 | 2549篇 |
1997年 | 2164篇 |
1996年 | 2040篇 |
1995年 | 1813篇 |
1994年 | 1451篇 |
1993年 | 1008篇 |
1992年 | 800篇 |
1991年 | 631篇 |
1990年 | 546篇 |
1989年 | 421篇 |
1988年 | 349篇 |
1987年 | 218篇 |
1986年 | 197篇 |
1985年 | 123篇 |
1984年 | 96篇 |
1983年 | 64篇 |
1982年 | 63篇 |
1981年 | 51篇 |
1980年 | 30篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1976年 | 15篇 |
1975年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
D Sternberg A Peled E Shezen O Abramsky W Jiang F Bertolero D Zipori 《Canadian Metallurgical Quarterly》1996,2(1):29-38
The immunological agglutination reactions of physically absorbed F(ab')2 molecules onto anionic and cationic latex particles have been investigated by means of optical absorbance measurements. These measurements have been conducted under different conditions to determine the most influential factors. Surface F(ab')2 and BSA densities, particle concentration in the reaction medium and polyethylene glycol concentration are some of these factors. Sensitized cationic and anionic latexes differ considerably with respect to their colloidal stability and reactivity. As a general rule, the sensitized cationic latex has a relatively higher colloidal stability and hence, it provides reagents with a better optical response. Less than 0.025 microgram/ml of C-reactive protein has been detected using this particle enhanced optical immunoassay. 相似文献
24.
Particulate TiB2 reinforced aluminum-based metal matrix composites (MMCs) were successfully fabricated by means of the reaction processing
method. TiB2 particulates were formed in situ through the reaction of Ti and B in Ti-Al-B, TiO2 and B in TiO2-Al-B, and TiO2 and B2O3 in TiO2-Al-B2O3 systems. The results showed that in situ TiB2 particulates formed in the Ti-Al-B system had a size of 5 μm and they exhibited block and rodlike structures. Moreover, coarse Al3Ti blocks several tens of micrometers in size were also formed simultaneously. On the other hand, equiaxed Al2O3 and TiB2 particulates with a size of less than 2 μm were formed in situ in the TiO2-Al-B and TiO2-Al-B2O3 systems. The Al3Ti phase was completely eliminated in the TiO2-Al-B system with increasing B content. Tensile tests revealed that the Al2O3 · TiB2/Al composite fabricated from the TiO2-Al-B system exhibits excellent mechanical properties. The yield strength of the Al2O3 · TiB2/Al composite appeared to increase with increasing TiB2 content. The yield strength of the Al2O3 · TiB2/Al composite could be further increased by introducing CuO into the TiO2-Al-B system. Such an increment in mechanical strength arose from the strengthening effect caused by the Al2Cu precipitates. The incorporation of CuO had no effect on the in situ reaction process of the TiO2-Al-B system. Finally, the effect of SiC addition on the microstructure and mechanical properties of the composites fabricated
from the TiO2-Al-B and TiO2-Al-B-CuO systems was also investigated. 相似文献
25.
Control of peak sidelobe level in adaptive arrays 总被引:1,自引:0,他引:1
Renbiao Wu Zheng Bao Yuanliang Ma 《Antennas and Propagation, IEEE Transactions on》1996,44(10):1341-1347
Adaptive beamforming techniques are now widely used to reject interference (jammer/clutter) signals in radar, communication, and sonar applications. In adaptive arrays using the sample matrix inversion (SMI) algorithm, inadequate estimation of the covariance matrix results in adaptive antenna patterns with high sidelobes and distorted mainbeams. In this paper, a method is proposed to precisely control the peak (rather than average) sidelobe level of adaptive array patterns. The proposed method is also generalized to adaptive array antennas with moderate bandwidth and large random amplitude and phase errors. Theoretical analysis and simulation results are provided to illustrate the performance of the method proposed 相似文献
26.
本文讨论了一个具有通用性的测试评估软件生成系统的设计思想和实现方法,给出了该生成器的系统组成、数据组织结构、查询搜索方式以及用户界面的设计。该系统具广泛的应用领域和实用意义。 相似文献
27.
We present the design of E-kernel, an embedding kernel on the Victor V256 message-passing partitionable multiprocessor, developed for the support of program mapping and network reconfiguration. E-kernel supports the embedding of a new network topology onto Victor's 2D mesh and also the embedding of a task graph onto the 2D mesh network or the reconfigured network. In the current implementation, the reconfigured network can be a line or an even-size ring, and the task graphs meshes or tori of a variety of dimensions and shapes or graphs with similar topologies. For application programs having these task graph topologies and that are designed according to the communication model of E-kernel, they can be run without any change on partitions connected by the 2D mesh, line, or ring. Further, E-kernel attempts the communication optimization of these programs on the different networks automatically, thus making both the network topology and the communication optimization attempt completely transparent to the application programs. Many of the embeddings used in E-kernel are optimal or asymptotically optimal (with respect to minimum dilation cost). The implementation of E-kernel translated some of the many theoretical results in graph embeddings into practical tools for program mapping and network reconfiguration in a parallel system. E-kernel is functional on Victor V256. Measurements of E-kernel's performance on V256 are also included 相似文献
28.
J. Jiang M. D. Olson 《International journal for numerical methods in engineering》1993,36(13):2219-2243
Numerical investigations are carried out to verify the new super element model developed in Reference 1 for non-linear analysis of stiffened box structures. The results presented here are obtained from a variety of examples which are chosen to illustrate the accuracy and convergence of the model in various applications. Good agreement is obtained for most of the problems considered and the present formulation is found to be accurate and economical for preliminary engineering design. 相似文献
29.
30.