全文获取类型
收费全文 | 115762篇 |
免费 | 1683篇 |
国内免费 | 867篇 |
专业分类
电工技术 | 1951篇 |
综合类 | 677篇 |
化学工业 | 15587篇 |
金属工艺 | 4008篇 |
机械仪表 | 3487篇 |
建筑科学 | 2452篇 |
矿业工程 | 890篇 |
能源动力 | 2241篇 |
轻工业 | 8354篇 |
水利工程 | 1439篇 |
石油天然气 | 2351篇 |
武器工业 | 45篇 |
无线电 | 8964篇 |
一般工业技术 | 19672篇 |
冶金工业 | 32676篇 |
原子能技术 | 2800篇 |
自动化技术 | 10718篇 |
出版年
2022年 | 685篇 |
2021年 | 1007篇 |
2020年 | 708篇 |
2019年 | 823篇 |
2018年 | 1989篇 |
2017年 | 2222篇 |
2016年 | 2798篇 |
2015年 | 1712篇 |
2014年 | 1966篇 |
2013年 | 3954篇 |
2012年 | 4411篇 |
2011年 | 5196篇 |
2010年 | 3008篇 |
2009年 | 3364篇 |
2008年 | 3204篇 |
2007年 | 3153篇 |
2006年 | 2732篇 |
2005年 | 5203篇 |
2004年 | 4365篇 |
2003年 | 3799篇 |
2002年 | 2535篇 |
2001年 | 2396篇 |
2000年 | 1938篇 |
1999年 | 2139篇 |
1998年 | 9430篇 |
1997年 | 6185篇 |
1996年 | 4293篇 |
1995年 | 2878篇 |
1994年 | 2312篇 |
1993年 | 2386篇 |
1992年 | 1229篇 |
1991年 | 1334篇 |
1990年 | 1348篇 |
1989年 | 1309篇 |
1988年 | 1218篇 |
1987年 | 1085篇 |
1986年 | 1069篇 |
1985年 | 1091篇 |
1984年 | 843篇 |
1983年 | 840篇 |
1982年 | 801篇 |
1981年 | 858篇 |
1980年 | 845篇 |
1979年 | 704篇 |
1978年 | 715篇 |
1977年 | 1364篇 |
1976年 | 2208篇 |
1975年 | 676篇 |
1974年 | 589篇 |
1973年 | 589篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Klimis?S.?NtalianisEmail author Anastasios?D.?Doulamis Nikolaos?D.?Doulamis Nikos?E.?Mastorakis Athanasios?S.?Drigas 《Journal of Signal Processing Systems》2015,80(2):153-161
In this paper, we present a novel memory access reduction scheme (MARS) for two-dimension fast cosine transform (2-D FCT). It targets programmable DSPs with high memory-access latency. It reduces the number of memory accesses by: 1) reducing the number of weighting factors and 2) combining butterflies in vector-radix 2-D FCT pruning diagram from two stages to one stage with an efficient structure. Hardware platform based on general purpose processor is used to verify the effectiveness of the proposed method for vector-radix 2-D FCT pruning implementation. Experimental results validate the benefits of the proposed method with reduced memory access, less clock cycle and fewer memory space compared with the conventional implementation. 相似文献
2.
3.
4.
5.
Klaus Reinhardt Hans Georg Breunig Aisada Uchugonova Karsten K?nig 《Journal of the Royal Society Interface》2015,12(110)
We explore the possibility of characterizing sperm cells without the need to stain them using spectral and fluorescence lifetime analyses after multi-photon excitation in an insect model. The autofluorescence emission spectrum of sperm of the common bedbug, Cimex lectularius, was consistent with the presence of flavins and NAD(P)H. The mean fluorescence lifetimes showed smaller variation in sperm extracted from the male (tau m, τm = 1.54–1.84 ns) than in that extracted from the female sperm storage organ (tau m, τm = 1.26–2.00 ns). The fluorescence lifetime histograms revealed four peaks. These peaks (0.18, 0.92, 2.50 and 3.80 ns) suggest the presence of NAD(P)H and flavins and show that sperm metabolism can be characterized using fluorescence lifetime imaging. The difference in fluorescence lifetime variation between the sexes is consistent with the notion that female animals alter the metabolism of sperm cells during storage. It is not consistent, however, with the idea that sperm metabolism represents a sexually selected character that provides females with information about the male genotype. 相似文献
6.
7.
V. I. Zubkov O. V. Kucherova I. N. Yakovlev A. V. Solomonov 《Russian Microelectronics》2015,44(3):203-209
An automated system for integrated electrophysical and optical studies of semiconductor nanoheterostructures, which operates in a wide temperature range from 15 to 475 K, is designed. The setup is intended to measure the temperature and frequency admittance and electroluminescence spectra of light-emitting diode and laser chips formed on substrates of diameter up to 50.2 mm, and the distribution of parameters over the wafer. The setup includes the closed-cycle helium cryogenic station, LCR meter, and temperature controller. The characterization results of nanoheterostructures with InGaN/GaN multiple quantum wells, which are used for creating highly efficient white and blue light-emitting diodes, are presented. 相似文献
8.
V. A. Eremenko V. N. Karpov V. V. Timonin N. G. Barnov I. O. Shakhtorin 《Journal of Mining Science》2015,51(6):1113-1125
The authors have determined the causes of drop in performance of induced block caving using fans of blastholes 105 mm in diameter and single blastholes 250 mm in diameter, as well as the sources of increased drilling cost and expansion of start-up time of production blocks in Abakan underground mine. Alternatives of improvement in drilling efficiency under current conditions are discussed. 相似文献
9.
Breslavs’kyi D. V. Metel’yov V. O. Morachkovs’kyi O. K. Tatarinova O. A. 《Strength of Materials》2019,51(5):753-760
Strength of Materials - Creep constitutive equations have been derived for the materials that exhibit the properties of orthotropy (transversal isotropy) and transient creep under cyclic loading. A... 相似文献
10.
High Temperature - Experimental findings suggest that a strongly ionized, arc He plasma of atmospheric pressure does not exist in the state of the local thermodynamic equilibrium (LTE) expected for... 相似文献