全文获取类型
收费全文 | 3947篇 |
免费 | 267篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 68篇 |
综合类 | 4篇 |
化学工业 | 1066篇 |
金属工艺 | 154篇 |
机械仪表 | 109篇 |
建筑科学 | 101篇 |
矿业工程 | 16篇 |
能源动力 | 155篇 |
轻工业 | 623篇 |
水利工程 | 40篇 |
石油天然气 | 13篇 |
无线电 | 224篇 |
一般工业技术 | 850篇 |
冶金工业 | 101篇 |
原子能技术 | 59篇 |
自动化技术 | 644篇 |
出版年
2024年 | 12篇 |
2023年 | 48篇 |
2022年 | 53篇 |
2021年 | 131篇 |
2020年 | 96篇 |
2019年 | 126篇 |
2018年 | 182篇 |
2017年 | 176篇 |
2016年 | 185篇 |
2015年 | 167篇 |
2014年 | 218篇 |
2013年 | 448篇 |
2012年 | 246篇 |
2011年 | 299篇 |
2010年 | 285篇 |
2009年 | 214篇 |
2008年 | 156篇 |
2007年 | 120篇 |
2006年 | 78篇 |
2005年 | 38篇 |
2004年 | 53篇 |
2003年 | 34篇 |
2002年 | 47篇 |
2001年 | 40篇 |
2000年 | 44篇 |
1999年 | 32篇 |
1998年 | 32篇 |
1997年 | 32篇 |
1996年 | 28篇 |
1995年 | 30篇 |
1994年 | 27篇 |
1993年 | 33篇 |
1992年 | 29篇 |
1991年 | 13篇 |
1990年 | 16篇 |
1989年 | 17篇 |
1988年 | 15篇 |
1985年 | 23篇 |
1984年 | 30篇 |
1983年 | 24篇 |
1982年 | 25篇 |
1981年 | 41篇 |
1980年 | 29篇 |
1979年 | 29篇 |
1978年 | 31篇 |
1977年 | 25篇 |
1976年 | 36篇 |
1975年 | 26篇 |
1974年 | 21篇 |
1973年 | 26篇 |
排序方式: 共有4227条查询结果,搜索用时 15 毫秒
101.
102.
103.
Jiří BarnatAuthor Vitae Petr BauchAuthor VitaeLuboš BrimAuthor Vitae Milan Češka 《Journal of Parallel and Distributed Computing》2012
Recent technological developments made various many-core hardware platforms widely accessible. These massively parallel architectures have been used to significantly accelerate many computation demanding tasks. In this paper, we show how the algorithms for LTL model checking can be redesigned in order to accelerate LTL model checking on many-core GPU platforms. Our detailed experimental evaluation demonstrates that using the NVIDIA CUDA technology results in a significant speedup of the verification process. Together with state space generation based on shared hash-table and DFS exploration, our CUDA accelerated model checker is the fastest among state-of-the-art shared memory model checking tools. 相似文献
104.
A novel split-and-merge algorithm for hierarchical clustering of Gaussian mixture models 总被引:2,自引:2,他引:0
Branislav Popovi? Marko Janev Darko Pekar Nik?a Jakovljevi? Milan Gnjatovi? Milan Se?ujski Vlado Deli? 《Applied Intelligence》2012,37(3):377-389
The paper presents a novel split-and-merge algorithm for hierarchical clustering of Gaussian mixture models, which tends to improve on the local optimal solution determined by the initial constellation. It is initialized by local optimal parameters obtained by using a baseline approach similar to k-means, and it tends to approach more closely to the global optimum of the target clustering function, by iteratively splitting and merging the clusters of Gaussian components obtained as the output of the baseline algorithm. The algorithm is further improved by introducing model selection in order to obtain the best possible trade-off between recognition accuracy and computational load in a Gaussian selection task applied within an actual recognition system. The proposed method is tested both on artificial data and in the framework of Gaussian selection performed within a real continuous speech recognition system, and in both cases an improvement over the baseline method has been observed. 相似文献
105.
106.
Stacking faults, which were detected in the Ag-In system, have been examined by transmission electron microscopy and electron diffraction. An enhanced concentration of stacking faults in splat cooled specimens as well as the formation of a metastable hexagonal phase in the f c c region of the alloy was observed. As far as we know this is the first case of the terminal solid solubility being reduced by rapid quenching. Terminal solid solubility is reduced because of the high concentration of structural defects introduced by quenching, e.g. dislocations and stacking faults, which serve as the nuclei for the transformation from the f c c to the h c p structure. Our measurements and calculations show that the stacking fault energy minimum is shifted to lower electron concentrations with respect to the stacking fault energy minimum corresponding to the equilibrium phase boundary for the f c c-h c p transformation. The new metastable phase boundary for this transformation was confirmed by X-ray examinations. We explain this earlier h c p phase appearance in rapid quenched specimens as the consequence of enhanced interaction of the Fermi surface and contracted Brillouin zone. The Brillouin zone contraction we attributed to quenched-in vacancies. 相似文献
107.
108.
We have found experimentally that rf SQUID's working in a nonhysteretic mode with small critical currents give exactly at resonance and at very low rf bias a triangular pattern with a period equal to half of one elementary quantum of magnetic flux. We discuss a possible explanation of this peculiar result. 相似文献
109.
B. Dimčić I. Cvijović M. T. Jovanović D. Božić O. Dimčić 《Journal of Materials Science》2006,41(13):4307-4313
This work considers structural and compression mechanical properties of three Ti3Al-based alloys processed by powder metallurgy. Mechanically alloyed powders were compacted by hot-pressing to non-porous
homogenous compacts. Prior to compression tests, all compacts were homogenized by a solution treatment at 1050°C (α + β region)
for 1h, followed by water quenching. The compression tests were performed from room temperature to 500°C in vacuum at a strain
rate of 2.4 × 10−3 s−1. Detailed microstructural characterization has been evaluated by scanning electron microscopy (SEM), followed by electron
dispersive spectroscopy (EDS) and X-ray diffraction analysis. Fracture topography was examined by SEM. The Ti3Al-Nb alloy exhibits the highest ductility in the whole temperature range, whereas addition of Mo to Ti3Al-Nb alloy yields the highest ultimate compression strength. A correlation between ductility and the fracture mode exists
for all materials. 相似文献
110.
Stones belong to porous materials where water in pores plays an important role during the freeze–thaw process. A thermophysical analysis based on the pulse transient method has been used to study an ageing cycle, namely the freeze–thaw cycle. Thermophysical analysis is based on measuring the thermophysical properties under specific thermodynamic conditions. The transient method determines the specific heat, thermal diffusivity, and thermal conductivity by a single measurement. A specimen of Sander sandstone was analyzed in both dry and water-saturated states. Typical anomalies of all thermophysical parameters at the freeze–thaw point as well as differences for the dry and saturated states were found. The changes of thermophysical parameters measured when using freeze–thaw cycles correspond to stone ageing. The freeze–thaw cycle can often be encountered in building physics, concrete construction, etcPaper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui, P. R. China. 相似文献