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41.
A polyorganosiloxane retaining a SiO4 tetrahedral framework has been synthesized by the reaction of an inosilicate mineral (para-wollastonite) with a trimethylsilylating reagent. The glassy product dissolved in a wide range of organic solvents but was insoluble in water. The analyses of the product by means of infra-red spectroscopy, X-ray powder diffraction and elemental analysis indicated that trimethylsilyl side groups were linked to the SiO4 framework. The thermal stability of the product was determined by thermal analysis. 相似文献
42.
Shoichi Nambu 《Water research》1971,5(12):1127-1134
A mathematical model based on the equilibrium of BOD materials in the activated sludge process was developed. When the excess sludge is negligibly small and the BOD concentration of the influent is given, the BOD concentration of the activated sludge or mixed liquor and the efficiency of BOD removal are determined only by the aeration period. Moreover, it was verified mathematically that the performance of the activated sludge process became unstable with decrease of the return sludge ratio and the aeration period. 相似文献
43.
Copolymerization of unsaturated polyester with styrene in water-in-oil (W/O) type emulsion was carried out with the use of various basic compounds as emulsifiers. It was found that a stable, gellike W/O type emulsion of unsaturated polyester resin is formed only when pKa's of the bases are above 6 and their concentrations are higher than some critical value. In these conditions, water can be dispersed in emulsion up to 900% to the resin. By polymerization, the stable W/O type emulsion is transformed to a white solid copolymer which is dry to the touch and which contains 90–95% of initially added water. It was confirmed that the basic compounds react with the carboxylic group of the polyester to form at the water-resin interface polyester salts, which act as true emulsifying agents. The stabilization mechanism of the emulsion at various concentrations of the polyester salt was investigated, mainly by microscopic observations, and an interpretation of the critical value of emulsifier concentration is proposed. 相似文献
44.
Silica films with a single-crystalline mesoporous structure 总被引:1,自引:0,他引:1
Miyata H Suzuki T Fukuoka A Sawada T Watanabe M Noma T Takada K Mukaide T Kuroda K 《Nature materials》2004,3(9):651-656
Films of mesoporous materials attract broad interest because of their wide applicability in the fields of optics and electronics. Although many of these films have a regular local porous structure, the structural regularity has not been used practically yet because of difficulties in its control on macroscopic scales. Here, we demonstrate the preparation of mesoporous silica films whose porous structure can be described as a single crystal, that is, a long-range order of cage-like pores is maintained over centimetre scales. These films have a three-dimensional hexagonal (space group P6(3)/mmc) porous structure, and the in-plane arrangement of the pores is strictly controlled by a polymeric substrate surface that has been treated by rubbing. This new class of single-crystalline films with mesoscopic periodic structure is a significant breakthrough in bottom-up nanotechnology, and could lead to novel devices, for example, optics in a soft X-ray region, and quantum electronics. 相似文献
45.
Elucidation of accuracy in calibration of MR signal intensity based on transmission amplitude method
To calibrate magnetic resonance (MR) signal intensity that depends on radio frequency (RF) coil loading, the transmission amplitude (TRA) for the excitation in the transmit-receive RF coil has been used as a good index in the so-called TRA method. As this TRA method needs neither an internal reference nor an additional external reference for the calibration, its accuracy is free from reference measurements. This study elucidated the calibration accuracy of MR signal intensities based on the TRA method. A cylindrical gel phantom was used for accuracy measurements with a 1.5-T MRI unit with conventional T1 imaging as a simple pulse sequence for various loading conditions. The brain parenchyma of eight healthy volunteers also showed calibrated MR signal deviations. The error of the phantom calibration measurements was 2.18% (S.D.%). The background noise intensity of images was theoretically derived to correlate with the impedance mismatching of the RF coil, which is inevitable for fixed tuning, even for automatic tuning that is not always exact. Taking into account this noise intensity, the calibration method was modified to reduce its error to 1.50%. The standard deviations of the calibrated values in the thalamus and frontal white matter were 2.9 and 3.8%, respectively. We suggest that the modified TRA method is a practical and reliable technique to obtain clinical numeric evidence. 相似文献
46.
Among passerines, Bengali finches are known to sing extremely complex courtship songs with three hierarchical structures:
namely, the element, the chunk, and the syntax. In this work, we theoretically studied the mechanism of the song of Bengali
finches in aides to provide a dynamic view of the development of birdsong learning. We first constructed a model of the Elman
network with chaotic neurons that successfully learned the supervisor signal defined by a simple finite-state syntax. Second,
we focused on the process of individual-specific increases in the complexity of song syntax. We propose a new learning algorithm
to produce the intrinsic diversification of song syntax without a supervisor on the basis of the itinerant dynamics of chaotic
neural networks and the Hebbian learning rule. The emergence of novel syntax modifying the acquired syntax is demonstrated.
This work was presented in part at the 11th International Symposium on Artificial Life and Robotics, Oita, Japan, January
23–25, 2006 相似文献
47.
Kazuyuki Chihara Caroline F. Mellot Anthony K. Cheetham Shani Harms Hirotaka Mangyo Masaki Omote Ryuichi Kamiyama 《Korean Journal of Chemical Engineering》2000,17(6):649-651
Equilibrium and isosteric heat of adsorption for the system of chloroform and USY-type zeolite were studied. The USY-type
zeolite (PQ Co., SiO2/Al2O3=70) was used both as a pure crystalline powder and as granulated particles with binder. Chloroform was reagent grade. The
adsorption equilibria were measured using a gravimetric method and were expressed as isotherms. A chromatographic method (i.e.
pulse response of chloroform through the USY column with helium carrier) was used to get the initial slope of the isotherms.
In the simulation, the GCMC method was used to calculate amounts adsorbed for various conditions. FF parameters were confidently
applied. And modified structure model was effective for simulation.
This paper was presented at The 5th International Symposium on Separation Technology-Korea and Japan held at Seoul between
August 19 and 21, 1999. 相似文献
48.
Toshiyuki Miyamoto Tomohiro Kitayama Sadatoshi Kumagai Kazuyuki Mori Syoichi Kitamura Seiichi Shindo 《Electrical Engineering in Japan》2008,162(4):54-63
Abatement of CO2 emission is one of the most important issues in the 21st century regarding preservation of the earth environment. This paper addresses a utility operations planning problem for distributed energy management systems (DEMSs), where we are to obtain optimal plans that minimize both costs and CO2 emissions. A DEMS consists of multiple entities that seek their own economic profits. In this paper, we give a mathematical formulation of the utility operations planning problem for each entity, and propose an energy trading market, which utlizes a multi‐attribute auction protocol in order to deal with both a price and a CO2 emission rate. Experimental results show that collaboration among entities through the market provides a more profitable plan for each entity and abatement of CO2 emission is also achieved. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(4): 54–63, 2008; Published online in Wiley InterScience ( www.interscience.wiley. com ). DOI 10.1002/eej.20418 相似文献
49.
Here, the development of ordered mesoporous silica prepared by the reaction of layered silicates with organoammonium surfactants is reviewed. The specific features of mesoporous silica are discussed with relation to the probable formation mechanisms. The recent understanding of the unusual structural changes from the 2D structure to periodic 3D mesostructures is presented. The formation of mesophase silicates from layered silicates with single silicate sheets depends on combined factors including the reactivity of layered silicates, the presence of layered intermediates, the variation of the silicate sheets, and the assemblies of surfactant molecules in the interlayer spaces. FSM‐16‐type (p6mm) mesoporous silica is formed via layered intermediates composed of fragmented silicate sheets and alkyltrimethylammonium (CnTMA) cations. KSW‐2‐type (c2mm) mesoporous silica can be prepared through the bending of the individual silicate sheets with intralayer and interlayer condensation. Although the structure of the silicate sheets changes during the reactions with CnTMA cations in a complex manner, the structural units caused by kanemite in the frameworks are retained. Recent development of the structural design in the silicate framework is very important for obtaining KSW‐2‐based mesoporous silica with molecularly ordered frameworks. The structural units originating from layered silicates are chemically designed and structurally stabilized by direct silylation of as‐synthesized KSW‐2. Some proposed applications using these mesoporous silica are also summarized with some remarks on the uniqueness of the use of layered silicates by comparison with MCM‐type mesoporous silica. 相似文献
50.
Shigeru Tanaka Kazuyuki Hokamoto Seiichi Irie Toshihiko Okano Zoran Ren Matej Vesenjak Shigeru Itoh 《Measurement》2011,44(10):2185-2189
Porous materials such as aluminum foam have been investigated for possible use as impact shock absorbers in transportation aeronautic applications. However, the response of aluminum foam during impacts at high velocities of more than 100 m/s is not yet fully understood. A high-velocity impact experiment was therefore carried out to clarify impact shock absorption properties of aluminum foam. A one-stage powder gun was used to accelerate an aluminum foam sample to impact a rigid wall. Velocity and deformation of the aluminum foam sample during impact was studied using a digital high-speed video camera, while the pressure wave in the aluminum foam sample was measured using a PVDF gauge. The experimental observations revealed uneven collapse of the aluminum foam sample structure during high speed impact with a general stress plateau effect, typical for cellular material structures when subjected to quasi-static loading. 相似文献