全文获取类型
收费全文 | 1320篇 |
免费 | 77篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 14篇 |
综合类 | 3篇 |
化学工业 | 295篇 |
金属工艺 | 43篇 |
机械仪表 | 61篇 |
建筑科学 | 71篇 |
矿业工程 | 2篇 |
能源动力 | 170篇 |
轻工业 | 180篇 |
水利工程 | 6篇 |
石油天然气 | 2篇 |
无线电 | 105篇 |
一般工业技术 | 208篇 |
冶金工业 | 48篇 |
原子能技术 | 4篇 |
自动化技术 | 190篇 |
出版年
2024年 | 8篇 |
2023年 | 12篇 |
2022年 | 27篇 |
2021年 | 46篇 |
2020年 | 48篇 |
2019年 | 60篇 |
2018年 | 54篇 |
2017年 | 57篇 |
2016年 | 59篇 |
2015年 | 46篇 |
2014年 | 55篇 |
2013年 | 122篇 |
2012年 | 73篇 |
2011年 | 105篇 |
2010年 | 77篇 |
2009年 | 103篇 |
2008年 | 92篇 |
2007年 | 72篇 |
2006年 | 49篇 |
2005年 | 41篇 |
2004年 | 16篇 |
2003年 | 24篇 |
2002年 | 24篇 |
2001年 | 21篇 |
2000年 | 19篇 |
1999年 | 16篇 |
1998年 | 17篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1978年 | 2篇 |
1974年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有1402条查询结果,搜索用时 15 毫秒
991.
Uğur Kölemen Orhan Uzun Cem Emeksiz Fikret Yılmaz Atilla Coşkun Ahmet Ekicibil Bekir Özçelik 《Journal of Superconductivity and Novel Magnetism》2013,26(11):3215-3219
Polycrystalline superconducting Bi–Pb–Gd–Sr–Ca–Cu–O bulk samples with nominal composition Bi1.7Pb0.3?x Gd x Sr2Ca3Cu4O12+y (x=0.00,0.01,0.05) were produced by the melt quenching method. The mechanical properties of the samples were characterized by depth sensing indentation technique under different peak loads ranging from 200 to 1800 mN. The experimental data were comparatively analyzed by the Oliver–Pharr method and a work of indentation approach. It was found that the work of indentation approach gave more reliable results because of the reducing pile-up effect. The results implied that both microhardness and reduced elastic modulus increased with increasing Gd substitution. 相似文献
992.
Ahmet Mete Asiye Uluğ Bülent Uluğ 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(3):457-466
Abstract Diels-Alder cycloaddition of furfural to C60 in toluene has been realised. UV-VIS, FTIR and 1H-NMR investigations suggest that the conjugated structure of furfural was changed into a non-conjugated structure in the product. 相似文献
993.
Mustafa Akyol Ahmet Ekicibil Tezer Fırat Kerim Kıymaç 《Journal of Superconductivity and Novel Magnetism》2013,26(7):2439-2445
In this study, Dy-doped ZnO (Zn0.8?4x Dy x O y (0.05≤x≤0.10)) samples were prepared by the solid-state reaction method, and were characterized by using the XRD, SEM and EDX techniques. The SEM results clearly demonstrate that the grains of the samples are very well connected to each other and tightly packed. From the XRD and EDX spectra, it has been concluded that the substituting of Dy3+ for Zn2+ in ZnO causes almost no change in the hexagonal wurtzite structure of ZnO. However, the lattice parameters a and c of Dy-doped ZnO are slightly different from those of the pure ZnO. These observations may be due to the slightly different ionic sizes of Zn2+ and Dy3+ ions. Our magnetization measurements (M–H) and (M–T) show paramagnetic behavior with a negative value of the Curie–Weiss temperature, corresponding to an antiferromagnetic exchange coupling in Dy-doped ZnO. Since, for low magnetic fields the extrapolation of the H/M versus temperature curves cut the T axes at negative values, we believe that the substitution of Dy in ZnO causes an overwhelming antiferromagnetic interaction for x≤0.10. 相似文献
994.
Ahmet Ozbilen Murat Aydin Ibrahim Dincer Marc A. Rosen 《International Journal of Hydrogen Energy》2013
A comparative environmental study is reported of nuclear-based hydrogen production using thermochemical water decomposition cycles. The investigation uses a life cycle assessment (LCA) as is an analytical tool to evaluate and reduce the environmental impact of the system or product. The LCA results are presented in terms of acidification potential and global warming potential. Since LCA often utilizes software to model and analyse the system, an artificial neural network (ANN) method can be advantageous. Here, an ANN method is applied to a nuclear-based hydrogen production system. Using an ANN method in this study eliminates the need to use LCA software separately and facilitates the determination of the impacts of altering input parameters of a system (e.g., heat, work, production capacity and plant lifetime). The neural network approach to identify the best system option, consistent with LCA software results, is developed here using ten neurons in the hidden layers. 相似文献
995.
Effect of partial substitution of caprine milk for ovine milk,dry salting and cured scalding on lipolysis in Urfa cheeses
下载免费PDF全文
![点击此处可从《International Journal of Dairy Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ahmet Ferit Atasoy 《International Journal of Dairy Technology》2015,68(3):381-388
The objectives of this study were to determine the effect of partial substitution of caprine for ovine milk, dry salting and curd scalding on the free fatty acid (FFA) level of Urfa cheeses. At the end of storage, lauric and linoleic acids were lower in cheese made from milk where up to the 30% partial substitution of caprine milk for ovine milk was made. Dry salted cheeses had higher butyric, lauric, linoleic and linolenic acid levels, and lower palmitic acid levels than their scalded counterpart. A relative increase in short‐chain FFAs occurred during ripening. Palmitic and oleic acids were the most abundant FFAs in fresh and ripened Urfa cheeses. 相似文献
996.
This article develops a solution methodology for project time compression problems in CPM/PERT type networks with convex or concave activity cost-duration functions. The proposed procedure actually approximates these relationships by piece-wise linear time-cost curves. The solution procedure is based on the Benders decomposition approach and seeks to minimize die total direct cost of a project subject to activity precedence relationships, as well as upper/lower bounds on activity durations. The computational efficiency of the proposed decomposition methodology is also discussed. 相似文献
997.
Ahmet S. Yigit A. Galip Ulsoy Ali Allahverdi 《Journal of Intelligent Manufacturing》2002,13(4):309-316
The problem of optimizing modular products in a reconfigurable manufacturing system is addressed. The problem is first posed as a generalized subset selection problem where the best subsets of module instances of unknown sizes are determined by minimizing an objective function that represents a trade-off between the quality loss due to modularization and the cost of reconfiguration while satisfying the problem constraints. The problem is then formulated and solved as an integer nonlinear programming problem with binary variables. The proposed method is applied to the production of a modular drive system composed of a DC motor and a ball screw. The study is a first attempt toward developing a systematic methodology for manufacturing modular products in a reconfigurable manufacturing system. 相似文献
998.
The thermal effectiveness and entropy generation of parallel and counter‐flow heat exchangers handling high‐viscosity fluids have been numerically investigated. Both the viscous friction and the viscosity variations with temperature were considered in the analysis. The results show that the thermal effectiveness–NTU curves deviate gradually from the curves obtained using the assumption that the effect of viscosity is negligible. Moreover, the consideration of the viscous frictional heating effect results in a considerable increase in the heat exchanger entropy. An optimum heat exchanger size could be determined from both first law and second law of thermodynamics points of view. The results show also that the effect of viscous friction with variable viscosity becomes more significant for lower inlet temperatures of high‐viscosity fluid. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
999.
Liquid state radiation-induced and electroinitiated polymerisations of epoxycyclopentane (ECP) have been investigated. Dichloromethane and tetrabutylammonium hexafluoro-phosphate were employed as a solvent electrolyte couple. Temperature effects on the rate of electroinitiation were also studied. Apparent activation energy for the electroinitiated polymerisation was calculated from the Arrhenius plot. The propagation of the polymerisation for both methods was found to be through the opening of the epoxy ring, as verified by i.r. and n.m.r. spectra. Both methods of polymerisation yielded tacky, amorphous polymers. 相似文献
1000.
Biodiesel production from pomace oil and improvement of its properties with synthetic manganese additive 总被引:1,自引:0,他引:1
Renewable energy sources are attracting more attention due to lower cost and lower pollution relative to fossil fuels. The aim of this experimental work is the production of renewable and clean methyl ester from pomace oil as an alternative fuel. This oil was obtained from pomace which is the waste of olive oil plants. Optimum producing conditions were determined experimentally. The maximum yield was obtained at 30% of methanol/oil ratio, 60 °C temperature for 60 min with NaOH catalyst. The properties of the biodiesel thus obtained were compared with diesel fuel requirements. An organic based Manganese additive improved the biodiesel properties. Doping the fuel at a ratio of 12 μmol/l oil methyl ester led to a 20.37% decrease in viscosity, 7 °C fall in the flash point and reduced the pour point from 0 °C to −15 °C. This blend of pomace oil methyl ester-diesel fuel with manganese additive was tested in a direct injection diesel engine. The maximum effect of the new fuel blend and diesel fuel on engine performance was obtained at 1400 rpm. 相似文献