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排序方式: 共有1217条查询结果,搜索用时 11 毫秒
91.
Douglas A SchwerJohn E Tolsma William H Green JrPaul I Barton 《Combustion and Flame》2002,128(3):270-291
A method of updating and reusing legacy FORTRAN codes for combustion simulations is presented using the DAEPACK software package. The procedure is demonstrated on two codes that come with the CHEMKIN-II package, CONP and SENKIN, for the constant-pressure batch reactor simulation. Using DAEPACK generated code, analytical derivative calculations, sparsity pattern information, and hidden discontinuity information can be obtained for the models of interest. This information can be easily integrated with different solvers giving the modeler great flexibility in selecting the best solution procedure. Using the generated code, the CONP code was connected to three different solvers, and the SENKIN code was connected to two different solvers. The effect of model formulation, analytical derivatives, sparsity, and sensitivity equation solution method were analyzed for three large kinetic mechanisms for methane, acetylene, and n-heptane. For the n-heptane model, with 544 species and 2446 reactions, a factor of 10-speed improvement over the original solution procedure was found using analytical derivatives and sparse linear algebra. For sensitivity calculations, for a small number of parameters, a factor of 55 improvement over the original solution procedure was found for the n-heptane problem. Upon closer examination of results, no one method is found to always be superior to other methods, and selection of the appropriate solution procedure requires an examination of the specific kinetic mechanism, which is easily conducted using DAEPACK generated code. 相似文献
92.
A common debugging strategy involves reexecuting a program (on a given input) over and over, each time gaining more information about bugs. Such techniques can fail on message-passing parallel programs. Because of nondeterminacy, different runs on the given input may produce different results. This nonrepeatability is a serious debugging problem, since an execution cannot always be reproduced to track down bugs. This paper presents a technique for tracing and replaying message-passing programs. By tracing the order in which messages are delivered, a reexecution can be forced to deliver messages in their original order, reproducing the original execution. To reduce the overhead of such a scheme, we show that the delivery'order of only messages involved inraces need be traced (and not every message). Our technique makes run-time decisions to detect and trace racing messages and is usuallyoptimal in the sense that the minimal number of racing messages is traced. Experiments indicate that only 1% of the messages are often traced, gaining a reduction of two orders of magnitude over traditional techniques that trace every message. These traces allow an execution to be reproduced any number of times for debugging. Our work is novel in that we adaptively decide what to trace, and trace only those messages that introduce nondeterminacy. With our strategy, large reductions in trace size allow long-running programs to be replayed that were previously unmanageable. In addition, the reduced tracing requirements alleviate tracing bottle-necks, allowing executions to be debugged with substantially lower execution time overhead.This work was supported in part by National Science Foundation grants CCR-8815928 and CCR-9100968, Office of Naval Research grant N00014-89-J-1222, and a grant from Sequent Computer Systems, Inc. 相似文献
93.
Three-dimensional (3-D) route-planning support offers a promising solution to overcome problems with wayfinding in complex indoor environments. An experiment was conducted to test the effect of 3-D route-planning support in a realistic setting, a large hospital building, during normal operation. Forty participants performed navigation tasks either with (n?=?20) or without (n?=?20) 3-D route-planning support. Support resulted in faster navigation, more use of artwork specifically installed to aid wayfinding, fewer navigation errors, less disorientation and less anxiety. In addition, participants used different strategies for wayfinding: without navigation support they used signs and route colour, but with navigation support they used not only the artwork, but also the existing furniture and other landmarks. The acceptance of 3-D route-planning support was high. Overall, the results support the value of 3-D route-planning support. 相似文献
94.
M. Hughes R. T. Barton S. A. G. R. Karunathilaka N. A. Hampson 《Journal of Applied Electrochemistry》1986,16(4):555-564
The problem of estimating the residual usable energy of a lead-acid cell has been intensified by the introduction of fully sealed units. These rely on the recombination of gaseous oxygen produced during overcharge at the positive electrode with the active material at the negative electrode. This introduction has removed the possibility of electrolyte density measurements, third electrode measurements and restricted residual capacity assessments to the two cell terminals. A method for this process is described using a parameter based on a characteristic frequency. The parameter is also a useful measure of cell ageing.Nomenclature
R
SOL
Ohmic resistance of cell ()
-
Charge-transfer resistance of positive and negative electrodes ()
-
CL
Double-layer capacitance of both positive and negative electrodes (F)
-
Warburg diffusion (S–1/2)
-
C
EXT
External series capacitor in analogue Fig. 5 (F)
-
R
EXT
External resistor in parallel withC
EXT in the anologue circuit Fig. 5 ()
-
IND
Inductor in Fig. 5 representing the geometrical effects of the cell at high frequencies (Henries)
-
R
IND
External resistor in parallel with IND in the analogue circuit Fig. 5 ()
-
Roughness factor allowing for the porosity of both electrodes 相似文献
95.
Totterdell Peter; Spelten Evelien; Smith Lawrence; Barton Jane; Folkard Simon 《Canadian Metallurgical Quarterly》1995,80(1):43
Although regulations on work hours usually include a minimum weekly rest period, there is little empirical evidence concerning recovery from work. Shift-working nurses (N?=?61) used a handheld computer for 28 days to complete self-ratings, cognitive-performance tasks, and a sleep diary. Many measures were worse on rest days that followed a night shift rather than a day shift and tended to be worse on 1st rest days compared with subsequent rest days. Alertness was lowest on the 1st rest day following a night shift. Social satisfaction was better on workdays that were preceded by 2 rather than 1 rest day. Reaction time (RT) decreased over consecutive night shifts and tended to increase over rest days following night shifts. The results are interpreted as being consistent with the combined adaptive costs of fatigue and adjustment to and from a nocturnal routine. The practical implications for scheduling rest days are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
96.
This paper argues that shiftworkers may have gradually habituated to their problems and hence that they underestimate them. Some support for this view was obtained in a 'reminiscence' questionnaire study of retired UK Police Officers who had all subsequently taken on another (mainly day-time) job. They completed a specially constructed questionnaire, which included several measures of health and well being, and in which they were asked to reminisce about how they had felt while still a shiftworker. These reminiscence scores were compared to their current perception of how they were. The results clearly indicated that individuals in retrospect perceive their situation as being worse than they realised at the time. This effect was most marked for scores on the General Health Questionnaire and Chronic Fatigue scale. The results of this study draw attention to a potential confounding in much of the shiftwork literature which demands further, more detailed, investigation. 相似文献
97.
Tumor Cell Phenotyping: Circulating Tumor Cell Phenotyping via High‐Throughput Acoustic Separation (Small 32/2018) 下载免费PDF全文
98.
Sefer Bora Lisesivdin Nadir Ali Khan Simone Mazzucato Naci Balkan Michael John Adams Ville-Markus Korpij?rvi Mircea Guina Gabor Mezosi Marc Sorel 《Nanoscale research letters》2014,9(1):22
We report the observation of room-temperature optical gain at 1.3 μm in electrically driven dilute nitride vertical cavity semiconductor optical amplifiers. The gain is calculated with respect to injected power for samples with and without a confinement aperture. At lower injected powers, a gain of almost 10 dB is observed in both samples. At injection powers over 5 nW, the gain is observed to decrease. For nearly all investigated power levels, the sample with confinement aperture gives slightly higher gain. 相似文献
99.
Julio J. Valdés Enrique Romero Alan J. Barton 《Expert systems with applications》2012,39(18):13193-13201
Visual data mining with virtual reality spaces is used for the representation of data and symbolic knowledge. High quality structure-preserving and maximally discriminative visual representations can be obtained using a combination of neural networks (SAMANN and NDA) and rough sets techniques, so that a proper subsequent analysis can be made. The approach is illustrated with two types of data: for gene expression cancer data, an improvement in classification performance with respect to the original spaces was obtained; for geophysical prospecting data for cave detection, a cavity was successfully predicted. 相似文献
100.
Parameter Sweep Workflows for Modelling Carbohydrate Recognition 总被引:1,自引:0,他引:1
Tamas Kiss Pamela Greenwell Hans Heindl Gabor Terstyanszky Noam Weingarten 《Journal of Grid Computing》2010,8(4):587-601
Carbohydrate recognition is a phenomenon critical to a number of biological functions in humans. Understanding the dynamic
behaviour of oligosaccharides should help in the discovery of the mechanisms which lead to specific and selective recognition
of carbohydrates by proteins. Computer programs which can provide insight into such biological recognition processes have
significant potential to contribute to biomedical research if the results of the simulation can prove consistent with the
outcome of conventional wet laboratory experiments. In order to validate these simulation tools and support their wider uptake
by the bio-scientist research community, high-level easy to use integrated environments are required to run massively parallel
simulation workflows. This paper describes how the ProSim Science Gateway, based on the WS-PGRADE Grid portal, has been created
to execute and visualise the results of complex parameter sweep workflows for modelling carbohydrate recognition. 相似文献