全文获取类型
收费全文 | 1350篇 |
免费 | 45篇 |
国内免费 | 73篇 |
专业分类
电工技术 | 35篇 |
综合类 | 63篇 |
化学工业 | 68篇 |
金属工艺 | 226篇 |
机械仪表 | 82篇 |
建筑科学 | 54篇 |
能源动力 | 15篇 |
轻工业 | 464篇 |
水利工程 | 21篇 |
武器工业 | 1篇 |
无线电 | 56篇 |
一般工业技术 | 171篇 |
冶金工业 | 22篇 |
原子能技术 | 26篇 |
自动化技术 | 164篇 |
出版年
2022年 | 7篇 |
2021年 | 14篇 |
2020年 | 10篇 |
2019年 | 17篇 |
2018年 | 12篇 |
2016年 | 10篇 |
2015年 | 11篇 |
2014年 | 53篇 |
2013年 | 238篇 |
2012年 | 79篇 |
2011年 | 114篇 |
2010年 | 71篇 |
2009年 | 90篇 |
2008年 | 42篇 |
2007年 | 38篇 |
2006年 | 56篇 |
2005年 | 25篇 |
2004年 | 44篇 |
2003年 | 25篇 |
2002年 | 15篇 |
2001年 | 12篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1998年 | 21篇 |
1997年 | 69篇 |
1996年 | 15篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 15篇 |
1992年 | 15篇 |
1991年 | 26篇 |
1990年 | 24篇 |
1989年 | 8篇 |
1988年 | 15篇 |
1987年 | 12篇 |
1986年 | 16篇 |
1985年 | 11篇 |
1984年 | 8篇 |
1983年 | 18篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 17篇 |
1979年 | 18篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 14篇 |
1975年 | 15篇 |
1974年 | 9篇 |
1957年 | 7篇 |
1956年 | 5篇 |
排序方式: 共有1468条查询结果,搜索用时 15 毫秒
111.
Kil-Sung LEE Hyeon-Kyeong SEO Yong-June YANG Woo-Chae HWANG Kwang-Hee IM In-Young YANG 《中国有色金属学会会刊》2011
The recent trend of vehicle design aims at crash safety and environmentally-friendly aspect. For the crash safety aspect, the energy absorbing members should absorb collision energy sufficiently but for the environmentally-friendly aspect, the vehicle structure must be light weight in order to improve the fuel efficiency and reduce the tail gas emission. Therefore, the light weight of vehicle must be achieved in a securing safety status of crash. An aluminum or carbon fiber reinforced plastics (CFRP) is representative one of the light-weight materials. Based on the respective collapse behavior of aluminum and CFRP member, the collapse behavior of hybrid thin-walled member was evaluated. The hybrid members were manufactured by wrapping CFRP prepreg sheets outside the aluminum hollow members in the autoclave. Because the CFRP is an anisotropic material whose mechanical properties, such as strength and elasticity, change with its stacking condition, the effects of the stacking condition on the collapse behavior evaluation of the hybrid thin-walled member were tested. The collapse mode and energy absorption capability of the hybrid thin-walled member were analyzed with the change of the fiber orientation angle and interface number. 相似文献
112.
在电力系统控制决策与运行分析中,对系统稳定运行区域的边界面几何形状的认识具有重要的意义。文中对注入功率空间中静态电压稳定域边界面(即潮流可解域边界)的二次特性进行了深入的探讨。通过对潮流方程雅可比矩阵的行列式在临界点附近进行泰勒级数展开并保留二次项,得到了计及非线性项的边界近似解析表达式。在计算过程中应用了潮流方程特征值和特征向量灵敏度系数的计算。该方法的优点是算法本身不涉及任何非线性方程的迭代求解,且所提出的非线性解析表达式能在大范围内较好地逼近真实稳定域边界。通过IEEE系统的算例对所提出的方法的精确性进行了验证。 相似文献
113.
114.
115.
116.
The changes in the size and shape of soybean protein bodies in different solvent systems were observed, and their influence on hydrodynamic properties in solutions was investigated by capillary viscometer. The intrinsic viscosity of the isolated protein bodies varied with the type of dispersion media; 0.036 cm3/g in CCI4-benzene solution, 0.355 cm3/g in 50% glycerol-water mixture, 0.574 cm3/g in water at pH 7, and 1.18 cm3/g in the aqueous solution at pH 12. The hydration of the protein bodies in different dispersion media was estimated by Oncley's method and Mooney's method. The estimated degree of hydration agreed well with the swelling of the protein bodies as observed by microscope. 相似文献
117.
SUMMARY— During fermentation a brewer's yeast released into the medium substantial amounts of materials absorbing ultra-violet light at 260 mμ These materials were separated by chromatography and identified by further chromatography and spectrophotometry. Nine nucleotides, five free bases (purines and pyrimidines) and four nucleosides were identified in the fermented medium and in the intracellular pool of the yeast. Some of these released materials may be of consequence in the fermented beverage industry since they were not reabsorbed by yeast and can be expected to persist to the finished product. 相似文献
118.
SUMMARY– The mutation or variation of a strain of Aspergillus flavus was induced chemically after six successive "generations" of exposures to barium ions. Colony isolates of A. flavus , developing from spores harvested from cultures grown in barium medium, were examined for mutation on the basis of morphology, loss of aflatoxin-producing capacity, and loss of ability to grow in basal medium. The new characteristics exhibited by the mutant of A. flavus are the inability to produce aflatoxins and yellow pigment, accompanied by the loss of fluorescence in the culture under ultraviolet light. These changes did not revert after more than eight successive transfers in a barium-free medium. Mutagenic action of barium ions on the fungus A. flavus was shown by the mutatation of colonies arising from single spores, The characteristics of the mutant are permanent and irreversible. 相似文献
119.
120.
Effect of Chlorophenoxyacetic Acid Growth-Regulator Sprays on Residues in Canned Apricots and Grapes
SUMMARY— A, gas-liquid chromatographic method coupled with an electron capture detector has been developed for analyzing chlorinated phenoxyacetic acid residues in canned fruits. The technique involves converting the acid to its methyl ester with diazomethane, chromatography on a 5% silicone grease SE-30 column at 210°C, and subsequent detection of the compound by an electron capture detector. As low as 0.02 ppm of the residue could be detected. The method is superior to the calorimetric method because parachlorophenoxyacetic acid (PCPA), 2,4-D, and 2,4,5-T can be separated and quantitatively determined simultaneously. However, separate standard curves are needed for each, because they differ in chlorine content and in sensitivity toward the electron capture detector. Levels of 2,4-D and 2,4,5-T residues in canned apricots, and of PCPA in canned grapes are reported. 相似文献