全文获取类型
收费全文 | 426篇 |
免费 | 41篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 36篇 |
综合类 | 19篇 |
化学工业 | 75篇 |
金属工艺 | 11篇 |
机械仪表 | 20篇 |
建筑科学 | 23篇 |
矿业工程 | 14篇 |
能源动力 | 20篇 |
轻工业 | 38篇 |
水利工程 | 12篇 |
石油天然气 | 32篇 |
无线电 | 27篇 |
一般工业技术 | 29篇 |
冶金工业 | 28篇 |
原子能技术 | 15篇 |
自动化技术 | 78篇 |
出版年
2024年 | 2篇 |
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 13篇 |
2020年 | 19篇 |
2019年 | 11篇 |
2018年 | 10篇 |
2017年 | 11篇 |
2016年 | 16篇 |
2015年 | 27篇 |
2014年 | 27篇 |
2013年 | 34篇 |
2012年 | 21篇 |
2011年 | 19篇 |
2010年 | 33篇 |
2009年 | 15篇 |
2008年 | 21篇 |
2007年 | 15篇 |
2006年 | 24篇 |
2005年 | 23篇 |
2004年 | 4篇 |
2003年 | 13篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 22篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有477条查询结果,搜索用时 0 毫秒
51.
Bo Yu Zhao-Xin Lu Xiao-Mei Bie Feng-Xia Lu & Xian-Qing Huang 《International Journal of Food Science & Technology》2008,43(7):1143-1151
Responses surface methodology was employed to enhance the production of protease and soybean peptides by Bacillus subtilis SHZ. For screening of medium composition significantly influencing protease and soybean peptides yield, the two-level Plackett–Burman design was used. Among thirteen variables tested; KH2 PO4 , glucose and defatted soybean flour (DSF) were selected based on their high significant effect on both protease activity and soybean peptides yield. Then, a three-level Box–Behnken design was employed to optimise the medium composition for the production of the protease and soybean peptides in submerged fermentation. Mathematical models were then developed to show the effect of each medium composition and their interactions on the production of protease and soybean peptides. The model estimated that, the maximal protease activity (320 ± 1 U mL−1 ) could be obtained when the concentrations of glucose, KH2 PO4 , DSF were set at 8–9 g L−1 , 2–3 g L−1 , 55–65 g L−1 , respectively; while a maximal yield of soybean peptides (8.5 ± 0.1 g L−1 ) could be achieved when the concentrations of glucose, KH2 PO4 , DSF were set at 7–9 g L−1 , 3–4 g L−1 and 55–58 g L−1 , respectively. These predicted values were also verified by validation experiments. 相似文献
52.
Shaowei Bie Jianjun Jiang Gang Du Qiang Ma Lin Yuan Yongjiang Di Zekun Feng Huahui He 《Journal of Alloys and Compounds》2008,463(1-2):471-474
CoNbZr films for an adjustable magnetic anisotropy field Hk by doping with rare-earth of different atomic ratio Tb element were obtained in this work. The effect of Tb addition ranged from 0 to 4 at.% on the magnetic properties of the amorphous CoNbZr films was further investigated. The results show that the magnetic anisotropy field Hk increases sharply with the addition of Tb while the coercivity Hch along the hard axis and Hce along the easy axis change slightly with increasing Tb content in the films. As a consequence, CoNbZr film doped with 2 at.% of Tb exhibits excellent soft magnetic properties with a saturation magnetization 4πMs of 8.9 kG, a hard axis coercivity Hch of 1.79 Oe, a easy axis coercivity Hce of 1.4 Oe and a magnetic anisotropy field Hk of 87 Oe. The measured ferromagnetic resonance frequency fFMR of this film is 2.30 GHz. The real permeability μ′ is about 100, which is maintained up to 2 GHz. In addition, there is a broad band of the imaginary permeability μ″ over a large frequency band, indicating high losses. Therefore, Tb doped CoNbZr film is an excellent candidate for high frequency applications such as electromagnetic interference suppressors. 相似文献
53.
考虑了一类齐次Neumann边界条件下具稀疏效应和扩散的捕食者-食饵模型,通过建立适当的Lyapunov函数得到其唯一的正平衡态解的全局渐近稳定性. 相似文献
54.
It is important to properly understand and calculate the distributions of the heat flux and the heat transfer coefficient in a furnace for designing a circulating fluidized bed (CFB) boiler, especially for one with supercritical parameters. An experimental study of the heat transfer in a commercial 300 MWe CFB boiler was conducted in this work. The heat flux from the bed to the waterwall was measured by a heat flux meter at four different heights. The influence of suspension density and bed temperature was analyzed by measuring the pressure profile and temperature profile in the furnace. In addition a numerical modeling study on the two phase flow in the furnace was carried out. The results indicate that the density of the solids suspension was non-uniform in the cross section at a certain height, and decreased gradually with increasing furnace height. Consequently, the distribution of heat flux in the horizontal plane was non-uniform and decreased along the height of the furnace. The heat flux showed a decreasing trend near the center. 相似文献
55.
56.
Calviello J.A. Bie P.R. Hickman G. Pomian P. Cappello A. Costello W. 《Electronics letters》1986,22(10):510-512
An all-refractory-metal GaAs MESFET (ARFET) making use of a Ta Schottky barrier with a thick gold overlayer for the source, gate and drain, and very highly doped N+-layers (2x1019 cm-3) to achieve low-resistivity nonalloyed ohmic contacts, has been successfully fabricated. These have a 400 ?m gate periphery and 0.6 ?m gate length and measured an associated gain of 10.22 dB and a noise figure of 2.14 dB at 8 GHz. The ARFETs were fabricated on epitaxial layers grown by MBE. Only one mask was used to simultaneously define source, gate and drain regions via a plasma dry-etch technique. 相似文献
57.
本文介绍了为进行煤浆系统光子输运研究而专门设计的Monte Carlo程序Mcphot,采用实验方法对该程序进行了标定,实验结果和计算结果符合得很好。 相似文献
58.
面向目标控制照明的合成波源偏移 总被引:11,自引:0,他引:11
应用Fourier有限差分算子,研究目标控制照明的合成波源偏移成像。平面波源与小束波源这些合成波源在目标控制照明下的偏移,都是通过增强对目标区域的有效照明来改善成像质量,通过减少非目标区域的计算冗余来提高计算效率。由分析和应用合成平面波源偏移和控制照明技术扩展开去,综合考虑平面波源和小束波源的合成与偏移,并通过有效照射合成波源的概念,分析合成波源的有利照明,进行面向目标区域的控制照明和合成波源偏移。最后,对具有速度强横向变化和陡倾角反射的复杂2D盐丘模型数据,做了相应的合成波源偏移数值试验。 相似文献
59.
Haizhen Zhao Zhaoxin Lu Fengxia Lu Xiaomei Bie Zhanmin Liu & Xiaoxiong Zeng 《International Journal of Food Science & Technology》2006,41(9):1027-1032
Enzymatic acidolysis of lard with caprylic acid was investigated. Of the five lipases that were tested in the initial screening, immobilised lipase TL IM from Thermomyces lanuginosus resulted in the highest incorporation of caprylic acid into lard. This enzyme was further studied for the effect of enzyme load, organic solvent, substrate ratio, reaction time and temperature. HPLC was used to analyse the products from the acidolysis reaction. The highest incorporation was attained at 15% enzyme load. Among the solvents tested, n‐hexane was the best reaction medium for the acidolysis of lard with caprylic acid. Time course studied suggests that the incorporation of caprylic acid into lard was increased up to 37.7 mol% after 24 h. Desirable mole ratio of lard to caprylic acid was 1:2, caprylic acid incorporation up to 34.2 mol%. Temperature had no significant effect on enzyme activity in the range of 40–80 °C. 相似文献
60.
机械CAD软件系统面向对象建模方法研究 总被引:3,自引:0,他引:3
以面向对象的减速器CAD系统的分析建模为例,对机械CAD系统采用面得对象技术建模的方法进行了研究,总结出此类CAD系统面向对象建模的一般特点。 相似文献