全文获取类型
收费全文 | 1432篇 |
免费 | 79篇 |
国内免费 | 16篇 |
专业分类
电工技术 | 27篇 |
综合类 | 7篇 |
化学工业 | 388篇 |
金属工艺 | 43篇 |
机械仪表 | 61篇 |
建筑科学 | 51篇 |
矿业工程 | 14篇 |
能源动力 | 96篇 |
轻工业 | 103篇 |
水利工程 | 10篇 |
石油天然气 | 41篇 |
无线电 | 131篇 |
一般工业技术 | 263篇 |
冶金工业 | 58篇 |
原子能技术 | 4篇 |
自动化技术 | 230篇 |
出版年
2024年 | 3篇 |
2023年 | 30篇 |
2022年 | 67篇 |
2021年 | 91篇 |
2020年 | 65篇 |
2019年 | 88篇 |
2018年 | 125篇 |
2017年 | 88篇 |
2016年 | 81篇 |
2015年 | 50篇 |
2014年 | 76篇 |
2013年 | 164篇 |
2012年 | 90篇 |
2011年 | 99篇 |
2010年 | 65篇 |
2009年 | 74篇 |
2008年 | 36篇 |
2007年 | 25篇 |
2006年 | 24篇 |
2005年 | 19篇 |
2004年 | 13篇 |
2003年 | 16篇 |
2002年 | 12篇 |
2001年 | 10篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 12篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 12篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 2篇 |
排序方式: 共有1527条查询结果,搜索用时 31 毫秒
81.
Mohammad Maududul Huq Md. Robiur Rahman Masnun Naher Mohammad Mizanur Rahman Khan Mostafa Kamal Masud Golam Mohammad Golzar Hossain Nianyong Zhu Yih Hsing Lo Muhammad Younus Wai-Yeung Wong 《Journal of Inorganic and Organometallic Polymers and Materials》2016,26(6):1243-1252
Two palladium(II) nitroaryl complexes trans-[bromo(p-nitrophenyl)bis(triphenylphosphine)palladium(II)] 1 and trans-[bromo(2,4-dinitrophenyl)bis(triphenylphosphine)palladium(II)] 2 have been synthesized. The complexes were characterized by FTIR and NMR (1H, 13C and 31P) spectroscopy and elemental analysis. The molecular structure of complex 2, as confirmed by X-ray crystallography, reveals that the Pd atom and its neighboring groups (two PPh3, Br and phenylene group) lie in a slightly distorted square plane. In the UV–Vis spectra of the complexes 1 and 2, the palladium to aryl charge transfer bands were observed. The emission peaks from the singlet excited states (S1 → S0) were observed in the photoluminescence spectra of the complexes. The thermal stability of the complexes has been studied by thermal gravimetric analysis (TGA). TGA data showed that both complexes are thermally stable up to 200 °C, and complex 1 is more stable than 2. The catalytic efficiency of the new palladium(II) complexes was studied as demonstrated using the Sonogashira coupling reactions with good yields. The experimental results suggest that the Sonogashira coupling reactions can be performed at moderate temperature (50 °C) using these new palladium(II) complexes as catalysts. 相似文献
82.
Processing of High‐Density Magnesia Spinel Electro‐Conducting Ceramic Composite and its Oxidation at 1400°C 下载免费PDF全文
Zaki Zaki Nasser Mostafa Yasser Ahmed Emad Ewais Mohamed Rashad 《International Journal of Applied Ceramic Technology》2016,13(4):662-669
Dense conductive ceramic composites of MgAl2O4 and MoSi2 were processed using combustion synthesis under‐load methodology. The starting reactants were blends of MoO3, SiO2, MgO, and Al powders. The study revealed that to obtain dense composite with homogeneous microstructure, 30 wt. % of MoSi2, 18.5 μm Al average particle size, and 175 MPa load are required. The produced dense composite was found to have a low apparent porosity (<1.0 vol. %), moderate density 4.61 g/cm3, and low electrical resistivity 0.3 Ωcm. The dense composite exhibited excellent thermodynamic stability between its phases at 1400°C in open atmosphere. 相似文献
83.
Jaber Gharib Mostafa Keshavarz MoravejiReza Davarnejad Mohamad Ebrahim Malool 《Chemical Engineering Research and Design》2013
Gas holdup and gas–liquid mass transfer coefficient were considered in an external airlift reactor. Air was sparged through some aliphatic alcohols (methanol, ethanol, n-propanol, and n-butanol) with different concentrations (0–1%, v/v). It was observed that gas holdup and mass transfer coefficient increased with increasing the number of carbons in alcohols. Furthermore, an increment in alcohols concentration increased gas holdup and mass transfer coefficient. The same behavior was observed in external and internal loop airlift reactors although gas holdup and mass transfer coefficient values were less than those of internal airlift reactor. According to the experiments, two correlations for gas holdup and mass transfer were developed. 相似文献
84.
85.
Synthesis and characterization of (poly (N-vinyl formamide)—pregelled starch—graft copolymer 总被引:1,自引:0,他引:1
Khaled M. Mostafa Abdul Rahim Samarkandy Azza A. El-Sanabary 《Journal of Polymer Research》2010,17(6):789-800
Bromate / cyclohexanone redox system was investigated as a novel initiator for graft copolymerization of N-vinyl formamide
onto pregelled starch. A number of variables in the grafting reaction were investigated including N-vinyl formamide, cyclohexanone,
bromate ion, sulphuric acid and pregelled starch concentrations, material to liquor ratio along with polymerization time and
temperature. The graft copolymers were evaluated in terms of graft yield, graft reaction efficiency and homopolymer formation
(%). The optimum conditions for grafting of N-vinyl formamide onto pregelled starch are: N-vinyl formamide 50% based on weight
of substrate, cyclohexanone 15 mmol / l, bromate ion, 30 mmol / l, liquor ratio 10, pH 6, time 120 min., and temperature 40°C.
On the other hand, characterizations of the resultant copolymers with respect to swelling capacity, solubility %, metal ion
up-take and suitability as a sizing agent for cotton textiles were investigated. The results obtained reflect that, the resultant
copolymer shows better results for the aforementioned properties in comparison with that obtained from native pregelled starch
as a starting substrate. 相似文献
86.
An exact three-dimensional analysis based on the linear potential theory and the elaborated method of eigenfunction expansion in elliptic coordinates are presented to study the free coupled elasto-hyrodynamic characteristics of an upright non-deformable cylindrical container of elliptical planform with a flexible bottom plate, filled to an arbitrary depth with an inviscid incompressible liquid. Extensive numerical data are presented in an orderly fashion for the first few symmetric/anti-symmetric coupled hydroelastic natural frequencies as a function of fluid depth parameter for two plate aspect ratios. Also, selected hydrodynamic and structural deformation modes shapes are presented in graphical form. The effects of liquid level, bottom plate elasticity, and cross sectional aspect ratio on the sloshing frequencies and hydrodynamic pressure modes are examined. The validity of the results is examined through computations using a commercial finite element package as well as by comparison with the data available in literature. 相似文献
87.
Mohamed Shaban Mostafa R. Abukhadra Ahmed Hamd 《Clean Technologies and Environmental Policy》2018,20(1):13-28
Glass was successfully recycled in the synthesis of mesoporous silica MCM-48 which was used as catalyst support for nickel oxide photocatalyst. The resulted products were evaluated using X-ray diffraction, scanning electron microscope and UV–Vis spectrophotometer. The precipitated nickel oxide is of Ni2O3 form and loading of it onto MCM-48 resulted in a reduction in the band gap energy from about 3.66 eV to about 2.4 eV. The role of MCM-48 as catalyst support for Ni2O3 in enhancing the adsorption capacity and photocatalytic properties of nickel oxide was evaluated through series of equilibrium studies and photocatalytic degradation of Congo red dye under visible light. Using of glass-based MCM-48 as catalyst support for Ni2O3 showed enhancing the adsorption capacity by 31.3 and 14.8% higher than the adsorption capacity of Ni2O3 and MCM-48, respectively. Also, the photocatalytic degradation percentage increased by about 67.3% relative to the Ni2O3 degradation percentage. The nature of MCM-48/Ni2O3 adsorption mechanism is chemisorption and occurs in multilayer form throughout the heterogeneous surface of the composite. The using of MCM-48 as support for Ni2O3 photocatalyst enhanced the adsorption capacity through increasing the total surface area. The loading process resulted in fixing of the Ni2O3 particles throughout the porous structure which producing more exposed active photocatalyst sites and active adsorption sites for the incident photons as well as preventing the nickel oxide particles from agglomeration. Based on the obtained results, supporting of Ni2O3 particles onto MCM-48 is promising active centers for the degradation of Congo red dye molecules. 相似文献
88.
Mohamed M. Mostafa 《Expert systems with applications》2009,36(8):11030-11038
This study uses self-organizing maps (SOM) to examine the effect of various psychographic and cognitive factors on green consumption in Kuwait. SOM is a machine learning method that can be used to explore patterns in large and complex datasets for linear and non-linear patterns. The results show that major variables affecting green consumption are related to altruistic values, environmental concern, environmental knowledge, skepticism towards environmental claims, attitudes toward green consumption, and intention to buy green products. The study also shows that SOM models are capable of improving clustering quality while extracting valuable information from multidimensional data. 相似文献
89.
Mostafa Sadooni 《Petroleum Science and Technology》2013,31(4):422-429
In gas condensate reservoirs, after a decrease in pressure below the dew point pressure, condensate formation would occur. One of the common and practical methods for prohibiting the rapid pressure drop in the reservoir and reduction of liquid dropout is gas injection. In this study, experimental measurement, the full field reservoir model and an economical evaluation have been performed to investigate the effect of nitrogen injection on an Iranian Southwestern gas condensate reservoir. At first, swelling and CVD tests were carried out to determine the swelling factor and changing the saturation pressure by nitrogen. Then, the full field simulation (history matching and prediction) was performed and finally an economical evaluation has been made. The results show that injecting more volumes of nitrogen cause to decrease the liquid dropout, increase the dew point pressure, and condensate ultimate recovery, but this process is not an economical project. 相似文献
90.
Mohamed H. Abd El‐Salam Arnold R. Hippen Kawther El‐Shafie Faiza M. Assem Hyam Abbas Mahmoud Abd El‐Aziz Osama Sharaf Mostafa El‐Aassar 《International Journal of Food Science & Technology》2011,46(10):2103-2110
Milk of high conjugated linoleic acid (CLA) level (1.25 g per 100 g milk fat) was produced by inclusion of fish oil and rousted soy bean in the ration of Holstein cows as compared to 0.55 g per 100 g milk fat in the milk of animals receiving control diet. Milk of normal (control) and high CLA content (treatment) was spray‐dried. Labneh was made from 20 g L?1 reconstituted milk using 3 mL per 100 mL yoghurt starter and 2 mL per 100 mL of probiotic cultures of Lactobacillus casei or Lactobacillus acidophilus. The control (C) and high CLA (T) labneh were analysed chemically and microbiologically, and their viscosities were determined during cold storage for 15 days. The fat content of labneh of high CLA was less than that of the control, but the total solids (TS) were unaffected by the CLA level. Labneh made with Lb. acidophilus had lower TS and higher acidity, exopolysaccharides and acetaldehyde contents and viscosity than that made with the use of Lb. casei. Labneh from the different treatments retained high counts of the added probiotic (>108 cfu g?1) throughout the storage period. The storage period had significant effects on all parameters determined. 相似文献