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951.
Yu-Chih Lin Chung-Liang Chang Tser-Sheng Lin Hsunling Bai Ming-Gu Yan Fu-Hsiang Ko Chia-Tien Wu Cheng-Hsiung Huang 《Korean Journal of Chemical Engineering》2008,25(3):446-450
This study utilized the activated carbon fiber (ACF) modified with metal catalyst via physical vapor deposition (PVD) process
(ACF/PVD) to diminish ozone. Furthermore, the ozone removal efficiency of ACF/PVD was compared with that of original ACF and
ACF modified with metal catalyst via impregnation process (ACF/impregnation). In addition to the kinds of coated metal and
the inlet ozone concentrations, the effects of the coating thickness and the reaction temperature on ACF/PVD for ozone removal
were also examined. The results indicate that the ozone removal efficiency of ACF/PVD is better than that of original ACF
and ACF/impregnation. The ozone removal efficiency of different metal-coated ACF/PVD in the superior order is gold (Au), and
manganese (Mn). The increase of Au-coated thickness (3 nm to 80 nm) on ACF/PVD will enhance the ozone removal. However, when
the Mn-coated thickness on ACF/PVD is larger than 15 nm, the ozone removal efficiency displays a declining trend. Furthermore,
a higher reaction temperature will result in a better ozone removal of ACF/PVD and the original ACF. 相似文献
952.
Ke Tang Li-juan SongLin-hai Duan Xiu-qi LiJian-zhou Gui Zhao-lin Sun 《Fuel Processing Technology》2008
Gallium atoms have been introduced into the framework of Y zeolite by treating the zeolite with an aqueous solution of ammonium hexafluoro gallate. Desulfurization of various model fuels containing about 500 μg/g sulfur were studied over the synthesized Y zeolite ([Ga]AlY) with a liquid hourly space velocity of 7.2 h− 1 at ambient conditions. The sulfur adsorption capacity was 7.0, 14.5, and 17.4 mg(S)/g adsorbent for thiophene, 4,6-dimethyldibenzothiophene (4,6-DMDBT), and tetrahydrothiophene (THT), respectively. The charges on S atom in thiophene, 4,6-DMDBT and THT, calculated by using density functional theory (DFT), are − 0.159, − 0.214 and − 0.298, respectively, implying that the S–M bond between the adsorption sites and thiophene is much weaker than that between the adsorption sites and THT or 4,6-DMDBT. 相似文献
953.
The hydrodechlorination (HDC) of chlorobenzene (abbreviated as CLB) and seven types of para-substituted chlorobenzenes (para-amino, -methoxy, -methyl, -chloro, -trifluoromethyl, -acetyl and -cyano: abbreviated as CLAN, CLAS, CLTN, DCLB, CLTF, CLAP and CLBN, respectively) were performed over 5%-ruthenium/carbon (Ru/C) under a hydrogen pressure of 0.5–1.5 MPa at 523 K.In the HDC of these model compounds, except for CLAP and CLBN, reductive cleavage between the carbon and chlorine atoms took place and dechlorinated compounds were produced preferentially. In the reaction of CLAP and CLBN, on the other hand, hydrogenation and/or hydrogenolysis of the substituent coincided with the HDC and a wide variety of products was observed accompanying the HDC product.For the chlorobenzenes of the simple HDC, the HDC reaction rate constants decreased in the orders of CLAN CLB ≈ CLTN ≈ CLAS and CLB > DCLB CLTF, respectively.In the reaction of the chlorobenzenes of the electron-donating substituent, the reaction constant (ln k/k0) has no relevance to the Hammett substituent constant (). In the case of the chlorobenzenes possessing the electron-withdrawing substituent, on the other hand, it was indicated that the electron-withdrawing substituent suppressed the HDC reactivity of chlorobenzenes, although no proportional relationship was observed between the reaction rate constant and the Hammett substituent constant.To explore the factors affecting the HDC reactivity, quantum calculation according to the DFT method (B3LYP/LANL2DZ) was applied to the “chlorobenzenes-Ru10” complex. As a result of the calculation, chlorobenzenes were adsorbed through a chlorine atom on the edge atom of the Ru10 cluster. The magnitude of the adsorption energy, moreover, decreased in the order of CLAN > CLAS ≈ CLB ≈ CLTN and CLB > DCLB > CLTF, respectively. These orders of adsorption energy are similar to that of the HDC reaction rate constant. It was concluded that adsorption energy is a useful parameter for the reactivity index of the HDC. 相似文献
954.
Jia Guo Ben Gui Shou-xin Xiang Xiu-ting Bao Hu-ji Zhang Aik Chong Lua 《Journal of Porous Materials》2008,15(5):535-540
Feasibility of producing activated carbons by utilizing solid wastes (extracted flesh fibre and seed shell) from palm oil
processing mills was investigated. The effects of activation conditions (CO2 flow rate, activation temperature and retention time) on the characteristics of the activated carbons, i.e. density, porosity,
BET surface area, pore size distribution and surface chemistry were studied. In this study, the optimum conditions for activation
were an activation temperature of 800 °C and a retention time of 30 min for fiber or 50 min for shell, which gave the maximum
BET surface area. Pore size distribution revealed that the shell-based activated carbons were predominantly microporous whilst
fiber activated carbon had predominant mesopores and macropores, suggesting the application of shell and fiber activated carbon
as adsorbents for gas-phase and liquid-phase adsorption, respectively. This was confirmed by further gas- and liquid-phase
adsorption tests. 相似文献
955.
D. Pokhrel T. Viraraghavan 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2008,140(1-3):165-172
A two-level seven-factor (27-2) fractional factorial design analysis was conducted to examine the parameters influencing dimethylarsinic acid (DMA) removal from an aqueous solution using iron oxide-coated A. niger biomass. The factors examined were the concentration of DMA in solution, the mass of the adsorbent, the solution temperature, the Ca2+ ions in solution, the Fe2+ ions in solution, the SO42− ions in solution, and the Cl− ions in solution. The magnitude of the influence of the factors considered on DMA removal was observed in the order: presence of Ca2+ ions in solution > the DMA concentration > solution temperature > presence of SO42− in solution > presence of Fe2+ in solution > the mass of adsorbent > the presence of Cl− in solution. 相似文献
956.
R. Krishna J.M. van Baten 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2008,140(1-3):614-620
Branched and cyclic hydrocarbons such as iso-butane, 2-methylpentane, 3-methylpentane, 2,2-dimethyl-butane and benzene are preferentially adsorbed at the intersections of the channels of MFI zeolite; they serve as bottlenecks for molecular traffic in mixtures with linear C1–C6 alkanes. Molecular dynamics simulations show that as the loadings of tardier iC4, 2MP, 3MP, 22DMB, and Bz is progressively increased to four molecules per unit cell the diffusivity of the more mobile linear alkane reduces nearly to zero. The reduction in the n-alkane diffusivity is quantitatively similar irrespective of the branched/cyclic hydrocarbon. 相似文献
957.
A. Vinu P. Srinivasu D.P. Sawant S. Alam T. Mori K. Ariga V.V. Balasubramanian C. Anand 《Microporous and mesoporous materials》2008,110(2-3):422-430
TiSBA-1 materials with extremely high Ti content, up to silicon to titanium ratio (nSi/nTi) of 2.4, have been successfully prepared through direct synthesis method by controlling the molar ratio of hydrochloric acid to silicon (nHCl/nSi). It has been found that the amount of Ti content and the structure of the TiSBA-1 can easily be controlled by the simple adjustment of nHCl/nSi ratio. X-ray diffraction pattern (XRD) of the obtained materials revealed that the materials are highly ordered and possess cubic three-dimensional cage type structure with open windows. N2 adsorption–desorption measurement confirmed the narrow pore size distribution, high specific surface area (1317–1491 m2 g−1), and large specific pore volume (0.68–0.75 cm3 g−1) for all the samples. UV–vis DR spectra of the prepared materials confirmed that Ti atoms are exclusively incorporated within silica framework and occupy the tetrahedral position while the presence of isolated bulk titania could be negligible. Morphologies of the TiSBA-1 materials have been also controlled by simply adjusting the nSi/nTi ratio. With the appropriate Ti content, TiSBA-1 materials can be obtained as regular fine spheres. Moreover, the detailed mechanism on the morphological and phase transition control, and the incorporation of high amount of Ti in the framework of TiSBA-1 materials has been also discussed in detail. 相似文献
958.
Adsorption of Remazol Red B on activated carbon prepared from olive stone and commercial activated carbon from aqueous solutions was compared. Different activating agent (ZnCl2) amounts and adsorbent particle size were studied to optimize adsorbent surface area. The adsorptive property of commercial activated carbon and activated carbon prepared from olive stone were investigated in terms of adsorbent dose, temperature, equilibrium time and pH. Then the obtained results were compared for all parameters, According to the results, the equilibrium time, optimum pH, adsorbent dosage were found 60 min, pH < 3–4 and 1.0 g/50 ml respectively. Lower adsorption capacity for RRB on activated carbon prepared from olive stone was found. The kinetic data for both adsorbents supports pseudo-second order model (r2 > 0.99) and intra-particle model (r2 > 0.95) but the first order kinetic model did not adequately fit to the experimental values (r2 < 0.76). The equilibrium adsorption data were interpreted using Langmuir and Freundlich models. The adsorption of Remazol Red B was better represented by the Langmuir equation. In addition, the thermodynamic parameters, standard free energy (ΔG°), standard enthalpy (ΔH°), standard entropy (ΔS°) of the adsorption process were calculated for both adsorbents. To reveal the adsorptive characteristics of the produced active carbon, surface area measurements were carried out and structural analysis was performed using SEM-EDS. 相似文献
959.
Ling Huang Qinlin Huang Huining Xiao Mladen Eic 《Microporous and mesoporous materials》2008,111(1-3):404-410
The work has been focused on utilizing mesoporous alumina MCM-48 material as a potential hydrotreating catalyst support for light-cycle oil (LCO) and exploring its adsorption ability for large aromatics. A series of Al-MCM-48 samples with various Si/Al ratios was synthesized via a hydrothermal method and characterized with X-ray diffraction (XRD), nitrogen adsorption isotherms, solid NMR, etc. The adsorption equilibrium isotherms of typical aromatics in LCO such as diaromatic 1-methylnaphthalene on Al-MCM-48 and MCM-48 samples were studied by a standard gravimetric technique. Compared with parent MCM-48, Al-MCM-48 samples exhibited higher adsorption capacity and stronger adsorption affinity towards the addressed aromatic compounds. The incorporation of alumina into MCM-48 materials generated acid centers and more hydroxyl groups on the support surface, which can provide enhanced adsorption for the sorbate molecules and dispersion of active phases. It was found that the adsorption behaviors of the aromatic compounds in Al-MCM-48 samples were mainly governed by the acidity of the support. The balance between pore volume and acid strength of Al-MCM-48 can be adjusted by altering Si/Al ratio. The influence of incorporation of Al on the framework and adsorption properties of the materials has also been investigated. 相似文献
960.
Ihsan Karabulut Ali Topcu Canan Akmil-Basar Yunus Onal Anna-Maija Lampi 《Journal of the American Oil Chemists' Society》2008,85(3):213-219
It is difficult to remove β-carotene from oils with alumina-column chromatography, because β-carotene is even less-polar than
triacylglycerols (TAGs) are. The objective of this study was to obtain butter oil TAGs free from β-carotene and antioxidants
via sequential treatments with activated carbon (AC) adsorption and alumina column chromatography. The AC used was prepared
from waste apricots. The effects of AC dosages, temperatures and time courses on β-carotene adsorption were studied. The Langmuir
and Freundlich isotherms were used to describe the adsorption of β-carotene onto AC, and it was found to be more consistent
with the Freundlich isotherm with a higher R
2 value (0.9784). Adsorption kinetics of β-carotene was analyzed by pseudo-first order and pseudo-second order models. The
pseudo-second order model was found to explain the kinetics of β-carotene adsorption more effectively (R
2 = 0.9882). The highest β-carotene reduction was achieved (from 31.9 to 1.84 mg/kg) at an AC dosage of 10 wt%, temperature
of 50 °C, and adsorption time of 240 min. A considerable amount of α-tocopherol was also adsorbed during the AC treatment.
Remaining portions of α-tocopherol were completely removed with alumina adsorption chromatography. The method described may
be used for purification of vegetable oil TAGs, which will be used as model compounds in model oxidation studies. 相似文献