全文获取类型
| 收费全文 | 3827篇 |
| 免费 | 49篇 |
| 国内免费 | 1篇 |
专业分类
| 电工技术 | 41篇 |
| 综合类 | 2篇 |
| 化学工业 | 906篇 |
| 金属工艺 | 70篇 |
| 机械仪表 | 75篇 |
| 建筑科学 | 155篇 |
| 矿业工程 | 6篇 |
| 能源动力 | 118篇 |
| 轻工业 | 284篇 |
| 水利工程 | 30篇 |
| 石油天然气 | 9篇 |
| 无线电 | 360篇 |
| 一般工业技术 | 667篇 |
| 冶金工业 | 665篇 |
| 原子能技术 | 20篇 |
| 自动化技术 | 469篇 |
出版年
| 2024年 | 35篇 |
| 2023年 | 32篇 |
| 2022年 | 61篇 |
| 2021年 | 96篇 |
| 2020年 | 81篇 |
| 2019年 | 74篇 |
| 2018年 | 74篇 |
| 2017年 | 66篇 |
| 2016年 | 94篇 |
| 2015年 | 67篇 |
| 2014年 | 85篇 |
| 2013年 | 187篇 |
| 2012年 | 165篇 |
| 2011年 | 187篇 |
| 2010年 | 157篇 |
| 2009年 | 132篇 |
| 2008年 | 175篇 |
| 2007年 | 161篇 |
| 2006年 | 136篇 |
| 2005年 | 113篇 |
| 2004年 | 113篇 |
| 2003年 | 85篇 |
| 2002年 | 85篇 |
| 2001年 | 66篇 |
| 2000年 | 73篇 |
| 1999年 | 68篇 |
| 1998年 | 156篇 |
| 1997年 | 106篇 |
| 1996年 | 84篇 |
| 1995年 | 85篇 |
| 1994年 | 66篇 |
| 1993年 | 80篇 |
| 1992年 | 49篇 |
| 1991年 | 38篇 |
| 1990年 | 34篇 |
| 1989年 | 29篇 |
| 1988年 | 29篇 |
| 1987年 | 32篇 |
| 1986年 | 29篇 |
| 1985年 | 23篇 |
| 1984年 | 25篇 |
| 1983年 | 33篇 |
| 1982年 | 22篇 |
| 1981年 | 29篇 |
| 1980年 | 21篇 |
| 1978年 | 29篇 |
| 1977年 | 32篇 |
| 1976年 | 38篇 |
| 1975年 | 20篇 |
| 1974年 | 25篇 |
排序方式： 共有3877条查询结果，搜索用时 15 毫秒
61.
Lowenstern JB Smith RB Hill DP 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2006,364(1845):2055-2072
Earth's largest calderas form as the ground collapses during immense volcanic eruptions, when hundreds to thousands of cubic kilometres of magma are explosively withdrawn from the Earth's crust over a period of days to weeks. Continuing long after such great eruptions, the resulting calderas often exhibit pronounced unrest, with frequent earthquakes, alternating uplift and subsidence of the ground, and considerable heat and mass flux. Because many active and extinct calderas show evidence for repetition of large eruptions, such systems demand detailed scientific study and monitoring. Two calderas in North America, Yellowstone (Wyoming) and Long Valley (California), are in areas of youthful tectonic complexity. Scientists strive to understand the signals generated when tectonic, volcanic and hydrothermal (hot ground water) processes intersect. One obstacle to accurate forecasting of large volcanic events is humanity's lack of familiarity with the signals leading up to the largest class of volcanic eruptions. Accordingly, it may be difficult to recognize the difference between smaller and larger eruptions. To prepare ourselves and society, scientists must scrutinize a spectrum of volcanic signals and assess the many factors contributing to unrest and toward diverse modes of eruption. 相似文献
62.
63.
64.
Algorithmic aspects and computational efficiency of the global‐basis two‐level method are investigated in the context of symmetric indefinite system of equations. The algorithm includes efficient construction of the global‐basis prolongator using Lanczos vectors, predictor–corrector smoothing procedures, and a heuristic two‐level feedback loop aimed at ensuring convergence. Numerical experiments consisting of 3D Helmholtz equations and shear banding problems with strain softening demonstrate the excellent performance of the method. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
65.
Jacob McDonald S. Komar Kawatra 《Mineral Processing and Extractive Metallurgy Review》2017,38(4):250-253
Plate water absorption has been traditionally used to assess the binding ability of bentonite clay binders for iron ore concentrate pelletization. Until 1997, there was an accepted test by ASTM, but due to inconstant data this method was withdrawn. This value, however, is still used by some pelletization operations to gauge the efficacy of their bentonite. This test procedure has only been investigated on inorganic binders and never organic binders. This paper seeks to confidently prove that PWA can be used to accurately determine the efficacy of starch binders both alone and in conjunction with bentonite. The role of bentonite as a binder for iron ore concentrate is not only to hold agglomerates together during high temperature operations. But during pelletization it can also mitigate many times its own weight in water. This water absorption capacity aids in retarding the growth rate of pellets, as faster growing pellets tend to be weaker. The value of this water absorption, known as plate water absorption (PWA), is used as a metric to determine the strength and quality of the resulting pellets by industrial pelletizing facilities. As new low silica binders seek to replace bentonite, they too must take on the role of moisture mitigation. This study has shown that starches with lower water absorption capacities tend to have lower compressive strengths. As the water absorption capacity increases so too does the compressive strength. When using only starch, higher absorption capacities lead to lower compressive strengths of pellets exposed to elevated temperatures. When bentonite is used in conjunction with starch, higher water absorption mixtures do exhibit an increase in strength when heated. 相似文献
66.
67.
68.
Ian Nascimento Vieira Beatriz Souza Leite Pires de Lima Breno Pinheiro Jacob 《International journal for numerical methods in engineering》2012,91(10):1023-1044
This work describes the development, implementation, and assessment of enhanced variants of three different groups of bio‐inspired methodologies: genetic algorithms, particle swarm optimization, and artificial immune system. The algorithms are implemented on a computational tool for the synthesis and optimization of offshore oil production risers that connect a floating platform at the sea surface to the wellheads at the sea bottom. Optimization procedures using bio‐inspired algorithms for such real‐world engineering problems require the calculation of the objective function through a large number of time‐consuming finite element nonlinear dynamic analyses, for the evaluation of the structural behavior of each candidate configuration. Therefore, the performance of the algorithms may be measured by the smaller number of objective function evaluations associated to a given target fitness value. The results indicate that the artificial immune system approach, incorporating some enhancements presented in this work, is more effective than the genetic algorithms and particle swarm optimization methods, requiring a smaller number of evaluations to obtain better solutions. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
69.
70.
本研究从不同来源的原料中分离得到18株具有产胞外多糖(EPS)能力的乳酸菌,通过对比发酵液及乳酸菌荞麦酸面团的乳化活性,获得一株产EPS且乳化活性较高的乳酸菌,并应用于荞麦酸面团的制作。采用动态流变测定、激光共聚焦观察、质构分析等手段,研究其对荞麦酸面团面包烘焙学特性的影响。结果表明:优选产乳化性多糖的乳酸菌YC'-22经鉴定为发酵乳杆菌(Lactobacillus fermentum strain HBUAS54017),且同源性为100%,EPS产量为1.63 g/L。通过添加乳酸菌荞麦酸面团,使面包面团的面筋网络结构得到强化。相比空白面包(CB),添加1.0%阿拉伯胶的荞麦面包(AGB)、荞麦酸面团面包(SDB)的比容分别增加了12.42%和14.08%,硬度分别降低了13.90%和22.87%;其中SDB面包整体可接受度最高,改善效果最明显。因此,产乳化性多糖的乳酸菌发酵的荞麦酸面团可以作为一种天然的面包功能配料。 相似文献