全文获取类型
收费全文 | 977篇 |
免费 | 51篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 287篇 |
金属工艺 | 23篇 |
机械仪表 | 17篇 |
建筑科学 | 40篇 |
矿业工程 | 5篇 |
能源动力 | 28篇 |
轻工业 | 165篇 |
水利工程 | 7篇 |
石油天然气 | 4篇 |
无线电 | 58篇 |
一般工业技术 | 162篇 |
冶金工业 | 122篇 |
原子能技术 | 2篇 |
自动化技术 | 105篇 |
出版年
2024年 | 4篇 |
2023年 | 19篇 |
2022年 | 69篇 |
2021年 | 63篇 |
2020年 | 22篇 |
2019年 | 37篇 |
2018年 | 43篇 |
2017年 | 40篇 |
2016年 | 36篇 |
2015年 | 22篇 |
2014年 | 34篇 |
2013年 | 71篇 |
2012年 | 52篇 |
2011年 | 55篇 |
2010年 | 43篇 |
2009年 | 43篇 |
2008年 | 33篇 |
2007年 | 37篇 |
2006年 | 46篇 |
2005年 | 23篇 |
2004年 | 15篇 |
2003年 | 21篇 |
2002年 | 19篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 12篇 |
1998年 | 10篇 |
1997年 | 4篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1971年 | 2篇 |
1958年 | 1篇 |
排序方式: 共有1030条查询结果,搜索用时 15 毫秒
41.
Shuo Huang Ádám Vida Anita Heczel Erik Holmström Levente Vitos 《JOM Journal of the Minerals, Metals and Materials Society》2017,69(11):2107-2112
The effects of V, Cr, and Mn on the magnetic, elastic, and thermal properties of FeCoNiCu high-entropy alloy are studied by using the exact muffin-tin orbitals method in combination with the coherent potential approximation. The calculated lattice parameters and Curie temperatures in the face-centered-cubic structure are in line with the available experimental and theoretical data. A significant change in the magnetic behavior is revealed when adding equimolar V, Cr, and Mn to the host composition. The three independent single-crystal elastic constants are computed using a finite strain technique, and the polycrystalline elasticity parameters including shear modulus, Young’s modulus, Pugh ratio, Poisson’s ratio, and elastic anisotropy are derived and discussed. The effects of temperature on the structural parameters are determined by making use of the Debye–Grüneisen model. It is found that FeCoNiCuCr possesses a slightly larger thermal expansion coefficient than do the other alloys considered here. 相似文献
42.
Precursor-Derived Si-B-C-N Ceramics: Oxidation Kinetics 总被引:1,自引:0,他引:1
Elke Butchereit Klaus G. Nickel Anita Müller 《Journal of the American Ceramic Society》2001,84(10):2184-2188
The oxidation behavior of three precursor-derived ceramics—Si4.46 BC7.32 N4.40 (AMF2p), Si2.72 BC4.51 N2.69 (AMF3p), and Si3.08 BC4.39 N2.28 (T2/1p)—was investigated at 1300° and 1500°C. Scale growth at 1500°C in air can be approximated by a parabolic rate law with rate constants of 0.0599 and 0.0593 μm2 /h for AMF3p and T2/1p, respectively. The third material does not oxidize according to a parabolic rate law, but has a similar scale thickness after 100 h. The results show that at least within the experimental times these ceramics develop extremely thin scales, thinner than pure SiC or Si3 N4 . 相似文献
43.
Understanding the individual's collectivistic orientations toward group goals and task activities is critical for developing cooperative and productive teams. The complex environment of modern construction, where the emphasis shifts from individually oriented to team‐based work, has led to many challenges. There are important issues of cooperative behaviours in a world of cultural pluralism in which interpersonal cooperation is juxtaposed with organizational citizenship behaviour. Behaviours of construction project participants are important manifestations of culture that are dependent upon norms, values and beliefs. Certain organizational cultures support individualistic behaviours while others emphasize the benefits to the collective whole. Collectivistic orientation is examined as the cultural dimension of individualism‐collectivism (IC) and found to be related to organizational citizenship behaviour (OCB) where the correlations of IC and most OCB variables are significant for quantity surveyors in Hong Kong. Generally, the (more) individualistic persons are less likely to exhibit organizational citizenship behaviours. 相似文献
44.
45.
46.
Ljerka Kratofil Krehula Zvonimir Katančić Anita Ptiček Siročić Zlata Hrnjak-Murgić 《木材化学与工艺学杂志》2014,34(1):39-54
Due to the widespread use of wood-plastic composites (WPCs), high-density polyethylene-wood flour composites (HDPE/WF) were studied in order to determine their stability in different application conditions. UV degradation and periodic absorption/desorption of moisture cause damaging changes to material during WPCs’ exterior application, so it is necessary to ensure WPCs’ durability against atmospheric influences. Samples were characterized by FTIR spectroscopy and scanning electron microscopy (SEM) in order to study the degradation after simulated weathering. The degree of water absorption was also determined. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used for the determination of composites’ thermal properties. Results show that the stability of the HDPE/WF composites to UV treatment highly depends on stabilizer content and its dispersion in the polymer matrix. Incompatibility of HDPE and wood particles is a major problem that should be solved to achieve good durability and satisfying properties in use. 相似文献
47.
Frances I. Hurwitz Richard B. Rogers Haiquan Guo Anita Garg Nathaniel S. Olson David Phan Jessica L. Cashman 《Journal of the American Ceramic Society》2020,103(12):6700-6711
High-porosity yttria- and ytterbia-stabilized zirconia aerogels offer the potential of extremely low thermal conductivity materials for high-temperature applications. Yttria- and ytterbia-doped zirconia aerogels were synthesized using a sol-gel approach over the dopant range of 0-20 atomic percent. Surface area, pore volume, and morphology of the as-dried aerogels and materials thermally exposed for short periods of time to temperatures up to 1200°C were characterized by nitrogen physisorption, scanning and transmission electron microscopy, and X-ray diffraction. The aerogels as supercritically dried all were X-ray amorphous. At a 5% dopant level, a tetragonal structure with a smaller monoclinic phase developed on thermal exposure. Mixed tetragonal and cubic phases or predominantly cubic materials were observed at higher dopant levels, depending on the dopant level, temperature and exposure time. The formation of crystalline phases was accompanied by loss of surface area and pore volume, although some mesoporous structure was maintained on short-term exposure to 1000°C. Incorporation of the smaller Yb atom into the lattice structure resulted in smaller lattice dimensions on crystallization than was seen with Y doping and favored a more highly equiaxed structure. Aerogels synthesized with 15% Y maintained the smallest particle size without evidence of sintering at 1100°C. Largest shrinkage and loss of pore volume occurred on crystallization from the amorphous phase, with further loss of pores at temperatures above 1000°C attributable to changes in lattice parameters. 相似文献
48.
James L. Smialek Michael D. Cuy Bryan J. Harder Anita Garg Richard B. Rogers 《Journal of the American Ceramic Society》2020,103(12):7014-7030
A thermal barrier coating (TBC) system survived 500 hours in aggressive, 1300°C burner rig testing. The yttria-stabilized zirconia (7YSZ) TBC was plasma sprayed on an oxidation-resistant Ti2AlC-type MAX phase and tested in a jet fuel burner at 100 m/s, using 5 hours cycles. No coating spallation or surface recession was observed; Al2O3-scale growth produced a slight 2.4 mg/cm2 mass gain. The coating surface exhibited craze-cracked colonies of [111]flourite textured columns, with no visible moisture attack. The 20 μm alumina scale remained intact under the YSZ face, about twice that producing failure for TBC/superalloy systems. TiO2 nodules, initially formed on the uncoated backside, were removed, and Al2O3 was etched through volatile hydroxides formed in water vapor (~10%). Overall, the test indicated exceptional stability of the YSZ/Al2O3/Ti2AlC system under turbine conditions due in large part to close thermal expansion matching. 相似文献
49.
Biosorption of nickel ions from aqueous solutions by natural and modified peanut husks: equilibrium and kinetics
下载免费PDF全文
![点击此处可从《Water and Environment Journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Katerina Atkovska Burevska Hamdije Memedi Kiril Lisichkov Stefan Kuvendziev Mirko Marinkovski Gordana Ruseska Anita Grozdanov 《Water and Environment Journal》2018,32(2):276-284
The toxicity and non‐biodegradation of heavy metals, as well as their tendency to accumulate in the soils, water resources and the living organisms, makes them the significant environmental pollutants. Therefore, the reduction and elimination of heavy metal ions from aqueous systems is very important from the ecological, nutritional and environmental reasons. The aim of this study is to investigate whether the natural peanut husks, an agricultural waste, and their chemically modified form are capable to remove Ni(II) ions from aqueous solutions using batch method and to compare their efficiency. The effects of the mass of the natural peanut husks and the initial pH of the solution were studied to find the optimal conditions for maximal removal of Ni(II) ions. MATLAB/Curve Fitting Toolbox was implemented to determine the adequate adsorption isotherm as well as to optimise the equilibrium state of the investigated systems. 相似文献
50.
In order to improve upon certain properties of gelatin graft copolymerization of acrylonitrile (AN) and methacrylonitrile (MAN) onto gelatin has been studied in aqueous medium using γ rays as a source of initiation. Optimum conditions for affording maximum percentage of grafting have been evaluated as a function of various reaction parameters. The grafted polyacrylonitrile (PAN) was isolated from the graft copolymer by acid hydrolysis, and the average molecular weight (Mv) of the isolated polymer has been determined viscometrically. The graft copolymers were characterized by IR spectroscopic methods and thermogravimetric analysis (TGA). Acrylonitrile was found to be more reactive than methacrylonitrile toward graft copolymerization. © 1994 John Wiley & Sons, Inc. 相似文献