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41.
Crossflow microfiltration, in which a suspension is passed through a pressurized open-ended tube or channel having microporous membrane walls, is an effective means of filtering fine particles from a liquid and is finding increasing application in separations involving microbial suspensions and products. The particles, which are carried toward the walls with the filtrate cross-flow, form a thin cake layer on the membrane surface which does not accumulate substantially but is rather swept along the channel by the tangential flow of suspension. This paper presents a stratified-flow model of this phenomenon which predicts the steady-state permeation flux, and the velocity, pressure, and concentrated particle layer thickness profiles, as functions of the system parameters. In addition, the results of laboratory experiments which used a crossflow microfiltration channel with glass sides are reported. The measured steady-state thickness of the cake layer as a function of distance from the channel entrance shows good agreement with the theory, except for the case of a relatively thick layer when it is believed that a stagnant sublayer had formed beneath the flowing cake layer. 相似文献
42.
We view the future of artificial intelligence from three perspectives: scientific, technological, and educational. The common theme among these views is the central importance of learning, particularly in problem domains where case-based reasoning seems appropriate. From a scientific perspective, an adequate model of the mind must account for the phenomena of learning. Learning must also be considered a technological requirement for computer systems both to facilitate the initial knowledge acquisition and ultimately to adapt to new situations. Finally, a scientific model of learning, together with AI technology, conform the basis for a new mode of education. This technology can be applied to instruction for a wide range of subjects. 相似文献
43.
Abstract The British Geological Survey has completed the conversion of both aeromagnetic and gravity survey records to a digital data base. This paper examines some of the uses of the aeromagnetic data base. Rendering digitized aeromagnetic data as a rectangular grid of interpolated anomaly values allows regional variations in subsurface magnetization to be displayed as images rather than contoured maps. Images of the magnetic field are more appropriate for visual interpretation and can be enhanced using standard methods of digital image processing. The optimum method is a combination of directional first-derivative filtering to impart the illusion of side illumination, with spectral colouring of the 8-bit range of DN, the former being used to modulate the brightness of the latter. As well as many of the known regional magnetic features of the Solway Basin, this method highlights several trends that were unsuspected. 相似文献
44.
ÈVE COSTE-MANIÈRE HOWARD H. WANG STEPHEN M. ROCK VINCENT RIGAUD ALEXIS PEUCH MICHEL PERRIER 《International journal of systems science》2013,44(10):1099-1110
Programming autonomous vehicles to accomplish complex missions is a complicated task for which the development of control architectures is of prime importance. The goal of this paper is to describe the accomplishments of both French and American teams within a cooperative research program focused on the development of high-level control of semi-autonomous underwater vehicles. In particular, two different mission-programming methodologies are examined in the context of the requirements of a generic, reactive and complex underwater mission. The French team uses a combination of the ESTEREL synchronous programming language and the PIRRAT real-time control library to implement a methodology derived from the ORCCAD programming system. The approach taken by the American team builds a trilevel hybrid architecture using the CONTROLSHELL real-time software development environment. The details of each methodology are highlighted through the presentation of the high-level programs designed by each team using their approach to control an underwater robot to perform a multiphased underwater mission. The utility of both programming methodologies was verified through the successful completion of those missions in experimental demonstrations by the French VORTEX and American OTTER autonomous underwater vehicles. 相似文献
45.
STEPHEN T. HARDIMAN CHRIS P. TSOKOSDagger; 《International journal of systems science》2013,44(8):879-900
Two basic forms of non-linear random integral equations are studied and where being the underlying set of a complete probability measure space (fi, A, P). The random process x(t; ω) is the unknown random function is the stochastic free term; the stochastic kernels are of convolution type, of linear and non-linear form, respectively, defined for and the processes are scalar functions defined for tsR+ and x£R.The object of this paper is to develop sufficient conditions for the existence of a, random solution, a second-order stochastic process, to the above equations. We utilize the methods of successive stochastic approximation and Banach's fixed point theorem to fulfil the objective. 相似文献
46.
HAIQIANG CHEN RAMASWAMY C. ANANTHESWARAN STEPHEN J. KNABEL 《Journal of Food Safety》2002,22(4):255-271
Shell eggs were inoculated internally with approximately 10 cells of Salmonella enterica serovar enteritidis (S. enteritidis) and subjected to three different cooling treatments. Eggs were cooled from an initial temperature of 27C to approximately 7.2C. After cooling, eggs were stored at approximately 7.2C for 36 days, or stored at 5.7–9.5C for 30 days plus 6 days at 37C to simulate temperature abuse. Rapid cooling and subsequent storage of eggs at approximately 7.2C inhibited the growth of S. enteritidis in eggs. Slow cooling, and/or temperature abuse promoted growth of S. enteritidis in eggs. The penetration study indicated that rapid cooling and subsequent storage at 7.2C for 30 days did not affect the penetration of S. enteritidis into egg contents. The S. enteritidis isolated from the eggshell with shell membranes was significantly higher (P < 0.05) than from the internal egg contents, indicating that most of the S. enteritidis cells were trapped within the shell pores and/or shell membranes. 相似文献
47.
Factors that significantly affect BAX® PCR detection of Listeria monocytogenes from optimized Penn State University (oPSU) broth were identified and optimized. Concentration of PCR product was significantly reduced by BAX™ protease and significantly increased by eliminating the lysis step and directly diluting oPSU broth prior to PCR. A simple oPSU broth-BAX® PCR-PicoGreen® (PSU-BAX-PicoGreen) system was developed and compared with current methods for detecting low levels of L. monocytogenes in commercial milk and hot dogs. All 30 milk samples inoculated with 10–20 CFU per mL L. monocytogenes were positive by FDA, BAX® and PSU-BAX-PicoGreen methods and all 42 uninoculated milk samples were negative by all of the above methods. All 30 hot dog samples inoculated with 10-20 CFU/g L. monocytogenes were positive by the USDA and PSU-BAX-PicoGreen methods, however, 2 hot dog samples gave indeterminate results with the standard BAX® method. All 42 uninoculated hot dog samples were negative by USDA, 9 were indeterminate by BAX® and 2 were positive by PSU-BAX-PicoGreen. The PSU-BAX-PicoGreen system may provide a simple and accurate method for rapidly screening pasteurized foods for both injured and noninjured L. monocytogenes. 相似文献
48.
Mathematical models which describe the effect of water activity on the rate of loss of ascorbic acid and β-carotene in a dehydrated sweet potato system were developed under isothermal storage conditions at 40°C. The p-carotene model was verified in several batches of sweet potato. It was found that, although the absolute magnitudes of the rates showed differences between batches, the model form remains appropriate for describing the effects of moisture. There fore, the models seem to be general, but model parameters must be identified for each specific system. 相似文献
49.
FOLLOWING THE THEORY OF DEMBER AND EARL, IT WAS PREDICTED THAT HOODED RATS WOULD BE MORE RESPONSIVE (IN TERMS OF APPROACH BEHAVIOR AND INSPECTION TIME) TO MODERATELY COMPLEX STIMULI THAN TO EITHER SIMPLE OR COMPLEX ONES. IN ORDER TO TEST THESE PREDICTIONS, SS WERE PLACED IN A DARK COMPARTMENT AND PERMITTED TO INSERT THEIR HEADS THROUGH A SMALL HOLE INTO AN ADJACENT COMPARTMENT ILLUMINATED THROUGH A TRANSLUCENT PANEL. 9 PANELS, PAINTED IN CHECKERBOARD PATTERNS, CONTAINED 2, 4, 9, 16, 25, 64, 100, 196, OR 256 ELEMENTS. EACH S WAS RUN FOR A SINGLE PERIOD OF 8 MIN.; 15 SS WERE USED ON EACH OF THE 9 STIMULUS PANELS. IT WAS FOUND THAT NUMBER OF APPROACHES TO THE PANELS DID NOT VARY SIGNIFICANTLY WITH STIMULUS COMPLEXITY, BUT THAT INSPECTION TIME PER APPROACH DID FOLLOW AN INVERTED U PATTERN. (FRENCH SUMMARY) (19 REF.) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
50.