全文获取类型
收费全文 | 2041篇 |
免费 | 84篇 |
专业分类
电工技术 | 25篇 |
综合类 | 2篇 |
化学工业 | 443篇 |
金属工艺 | 107篇 |
机械仪表 | 28篇 |
建筑科学 | 116篇 |
矿业工程 | 3篇 |
能源动力 | 79篇 |
轻工业 | 145篇 |
水利工程 | 16篇 |
石油天然气 | 2篇 |
无线电 | 199篇 |
一般工业技术 | 342篇 |
冶金工业 | 234篇 |
原子能技术 | 9篇 |
自动化技术 | 375篇 |
出版年
2023年 | 17篇 |
2022年 | 36篇 |
2021年 | 70篇 |
2020年 | 39篇 |
2019年 | 42篇 |
2018年 | 51篇 |
2017年 | 54篇 |
2016年 | 65篇 |
2015年 | 70篇 |
2014年 | 67篇 |
2013年 | 118篇 |
2012年 | 100篇 |
2011年 | 139篇 |
2010年 | 106篇 |
2009年 | 98篇 |
2008年 | 120篇 |
2007年 | 100篇 |
2006年 | 96篇 |
2005年 | 65篇 |
2004年 | 42篇 |
2003年 | 44篇 |
2002年 | 43篇 |
2001年 | 31篇 |
2000年 | 34篇 |
1999年 | 59篇 |
1998年 | 74篇 |
1997年 | 53篇 |
1996年 | 30篇 |
1995年 | 16篇 |
1994年 | 34篇 |
1993年 | 31篇 |
1992年 | 7篇 |
1991年 | 13篇 |
1990年 | 13篇 |
1989年 | 10篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 14篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1979年 | 4篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1976年 | 14篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1973年 | 3篇 |
排序方式: 共有2125条查询结果,搜索用时 593 毫秒
1.
2.
3.
The performance of sequential decoding of long constraint length convolutional codes is evaluated for Rayleigh fading channels. Sequential decoding is not practical below a certain theoretical signal-to-noise ratio, and these theoretical limits are calculated for a number of modulation methods and code rates. As an example, with BPSK modulation, soft decisions and code rate 1/2, the theoretical signal-to-noise ratio per information bit is 5.7 dB. Above this limit the bit error rate can be made arbitrarily small by increasing the constraint length at no significant complexity cost. Furthermore, it is shown that with carefully chosen quantization steps, 8 level uniform quantization gives a negligible loss also for sequential decoding on a Rayleigh fading channel. Simulation results using 8 level quantization correspond well with the theoretical performance bounds. Also, the performance on a correlated channel with finite interleaving has been obtained. With an interleaver depth of 50×50 and a normalized doppler frequency equal to 0.01 we are only 0.5 dB away from the performance with perfect interleaving. Finally, bit error rate results show this scheme to compete well with Turbo codes. 相似文献
4.
Henrik Lindstrm Eva Magnusson Anna Holmberg Sven Sdergren Sten-Eric Lindquist Anders Hagfeldt 《Solar Energy Materials & Solar Cells》2002,73(1):240
The present paper describes a new method for manufacturing a nanostructured porous layer of TiO2 on a conducting glass substrate for use in a dye-sensitized photoelectrochemical cell. The method involves deposition of a layer of semiconductor particles onto a conducting substrate and compression of the particle layer to form a mechanically stable, electrically conducting, and porous nanostructured film at room temperature. Photoelectrochemical characteristics and morphology of the resulting nanostructured films are presented. The potential use of the new manufacturing method in the future applications of nanostructured systems is discussed. 相似文献
5.
6.
7.
8.
Sven Hovmöller 《Ultramicroscopy》1985,17(2):175-192
We present a family of techniques for the transmission electron microscope that generate surface zone-axis patterns. These patterns display the variation of the diffracted-beam intensity as a function of the angle of the incident electrons. The conditions of the experiments are those of reflection high-energy electron diffraction at near grazing incidence. The techniques are: surface convergent-beam diffraction, a surface analogue of the Tanaka method and a modified double-rocking scheme. Experimental results are presented for diffraction from surfaces of MgO and MoS2. We anticipate that surface zone-axis patterns (surface ZAPs) will become established as an important tool for surface characterization, especially when used in conjunction with high-resolution surface imaging and surface energy loss spectroscopy; surface ZAPs may be expected to play, in surface analysis, a role analogous to that played by convergent-beam diffraction in normal transmission electron microscopy. 相似文献
9.
Sven Beyer Christian Jacobi Daniel Kröning Dirk Leinenbach Wolfgang J. Paul 《International Journal on Software Tools for Technology Transfer (STTT)》2006,8(4-5):411-430
In the verified architecture microprocessor (VAMP) project we have designed, functionally verified, and synthesized a processor
with full DLX instruction set, delayed branch, Tomasulo scheduler, maskable nested precise interrupts, pipelined fully IEEE
compatible dual precision floating point unit with variable latency, and separate instruction and data caches. The verification
has been carried out in the theorem proving system PVS. The processor has been implemented on a Xilinx FPGA.
A shorter version of this article with the title “Instantiating uninterpreted functional units and memory system: functional
verification of the VAMP” appeared in [8]. The work reported here was done while all the authors were with Saarland University. 相似文献
10.