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101.
Steven Hostyn Gitte VanBaelen Guy L.F. Lemire Bert U.W. Maes 《Advanced Synthesis \u0026amp; Catalysis》2008,350(16):2653-2660
9H‐α‐Carbolines have been prepared via consecutive intermolecular Buchwald–Hartwig reaction and Pd‐catalyzed intramolecular direct arylation from commercially available 2,3‐dichloropyridines and substituted anilines. The combination of a high reaction temperature (180 °C) and the use of DBU were found to be crucial for the intramolecular direct arylation reactions of the 3‐chloro‐N‐phenylpyridin‐2‐amines as no reaction was observed at 120 °C and 180 °C using different inorganic and other organic bases. On the other hand, nitrogen‐methylated pyridine analogues of these substrates {N‐[3‐chloro‐1‐methylpyridin‐2(1H)‐ylidene]anilines} do undergo ring closure at 120 °C, with K3PO4 as base, affording the respective 1‐methyl‐1H‐α‐carbolines in good yields. 相似文献
102.
Despite the efforts of governments and the various support programmes, achievement of advanced stages of e-commerce by small- and medium-sized enterprises (SMEs) is still very low. There have been some attempts to study the dynamic nature of websites, but there is still little research evidence to explain why and how SMEs evolve their web presence. This paper aims to develop a comprehensive classification of drivers for web site redesign based on interviews with various members of staff from SMEs in the U.K. that have recently redesigned their web sites. A sequential mixed-methodological analysis, involving the use of qualitative and quantitative data analysis, was used to develop the classification. This enabled the development of a framework that classified seven main categories of drivers for web site redesign. The drivers identified were: changing business requirements, evolving internet strategies, addressing user needs, maintenance, changing technology, pressure from peers/competitors, and the influence of developers. However, only the first four were found to be significant in the study. The categorisation and the findings suggest a number of key determinants not explicitly addressed by other work. In addition, the findings provide little support for the staged approach to e-commerce progression as few companies reported the implementation of sophisticated internet technology features as a main reason for their web site redesigns. The contributions of this paper are firstly, to provide an instrument to the academic and practitioner communities interested in the topic of web site evolution. Secondly, the categorisation of drivers for redesign and the individual reasons found in this study are expected to provide assistance to SME managers to justify, plan and strategise internet investments realistically and effectively. 相似文献
103.
Quentin Lequy Mathieu Bouchard Guy Desaulniers Fran?ois Soumis Beyime Tachefine 《Journal of Scheduling》2012,15(2):239-251
In some companies such as large retail stores, the employees perform different activities (e.g., cashier or clerk in a specific
department) to respond to a customer demand for each activity that varies over the planning horizon and must be fulfilled
as soon as possible. For a given time period, this demand translates into an ideal number of employees required for the corresponding
activity. During a work shift, an employee can be assigned to several activities that are interruptible at any time and subject
to operational constraints (required skills, minimum and maximum assignment durations). Given work shifts already assigned
to the employees, the multi-activity assignment problem (MAAP) consists of assigning activities to the shifts such that the
activity demands are satisfied as best as possible over the planning horizon. In this paper, we propose three integer programming
models for the MAAP and develop various heuristics based on mathematical programming techniques. Computational results obtained
on randomly generated MAAP instances show that a heuristic column generation method embedded into a rolling horizon procedure
provides the best results in general. 相似文献
104.
105.
Nathalie Meunier Myriam Chartier Guy Mercier Jean-Fran?ois Blais 《Canadian Metallurgical Quarterly》2009,135(9):869-875
Many problems are associated with pig manure production like high biochemical oxygen demand, chemical oxygen demand, nitrogen, and phosphorus contents. Manure produces may be used in land spreading for agricultural purposes. Over application of liquid manure or runoff caused by precipitation contribute notably to surface or overland flow of phosphorus. In this study, the LISOX process is proposed for use in medium size farms, namely a 2,000-head swine farm. The LISOX process uses biological passive flotation, without any gas addition, to enable the flocs to rise to the surface. Results show that this technology is able to considerably reduce the solids content in the final effluent to 1.1±0.3% and reached solids content of 17.9±2.6% in the combined solid manure obtained at the end of the LISOX process. Total phosphorus (Pt) concentrations have been reduced from 1,234±428?mg/L to 146±46?mg/L in the final effluent, while a value of Pt of 20.6±7.9?g/kg has been obtained in the final solid fraction of the treated manure. The initial ammonium ion/total phosphorus ratio of 2.3±1.0 has been increased to respectively 16.4±4.6 and 17.6±5.4 after the primary and the secondary flotation, which is clearly much higher than the target value (NH4/Pt>7). 相似文献
106.
Guy Hoover 《电子设计技术》2010,17(6)
引言
设计一种能够提供不打任何性能折扣的ADC驱动拓扑结构是颇具挑战性,特别是在围绕一款诸如1Msps LTC(R)2393-16等超低噪声SAR ADC进行设计的时候. 相似文献
107.
Cavalcanti OA Van den Mooter G Caramico-Soares I Kinget R 《Drug development and industrial pharmacy》2002,28(2):157-164
Oligosaccharides such as inulin (In) and polysaccharides such as galactomannans, combined with polymethacrylates on isolated films for film coatings, were obtained from aqueous-based solvents and investigated as potential vehicles for colonic drug delivery. These compositions, which are susceptible to fermentation by colonic microflora, constitute promising excipients for the development of new colon-specific therapeutic systems. The characteristics of several compositions have been demonstrated in permeability and swelling studies on isolated films composed of a polymethacrylate associated with In or galactomannans of mesquite seed gum (MSG). Results reported prove a dependency of the properties of mixed films on the polymethacrylate-polysaccharide concentration ratio and on the composition of the dissolution media. An increase in permeability through the mixed films was observed in a simulated colonic environment for the following compositions: Eudragit®RS30D-MSG 70 : 30 w/w; Eudragit® RS30D-In 90 : 10 w/w; Eudragit®RS30D-In 76 : 24 w/w. 相似文献
108.
Evans SA Elliott JM Andrews LM Bartlett PN Doyle PJ Denuault G 《Analytical chemistry》2002,74(6):1322-1326
Mesoporous (H(I)-ePt) platinum microelectrodes electrodeposited from the hexagonal (H(I)) lyotropic liquid crystalline phase are shown to be excellent amperometric sensors for the detection of hydrogen peroxide over a wide range of concentrations. Good reproducibility, high precision, and accuracy of measurements are demonstrated. Mesoporous microelectrodes retain the high rates of mass transport typical of conventional microelectrodes, and their high real surface area greatly enhances their catalytic activity. This unique combination of properties overcomes the limitations of previous amperometric hydrogen peroxide sensors and yields outstanding qualitative and quantitative results. 相似文献
109.
The Data Locality of Work Stealing 总被引:1,自引:0,他引:1
This paper studies the data locality of the work-stealing scheduling algorithm on hardware-controlled shared-memory machines,
where movement of data to and from the cache is solely controlled by the hardware. We present lower and upper bounds on the
number of cache misses when using work stealing, and introduce a locality-guided work-stealing algorithm and its experimental
validation.
{As a lower bound, we show that a work-stealing application that exhibits good data locality on a uniprocessor may exhibit
poor data locality on a multiprocessor. In particular, we show a family of multithreaded computations G
n
whose members perform Θ(n) operations (work) and incur a constant number of cache misses on a uniprocessor, while even on two processors the total
number of cache misses soars to Ω(n) . On the other hand, we show a tight upper bound on the number of cache misses that nested-parallel computations, a large,
important class of computations, incur due to multiprocessing. In particular, for nested-parallel computations, we show that
on P processors a multiprocessor execution incurs an expected
more misses than the uniprocessor execution. Here m is the execution time of an instruction incurring a cache miss, s is the steal time, C is the size of cache, and T
∈
fty is the number of nodes on the longest chain of dependencies. Based on this we give strong execution time bounds for nested-parallel
computations using work stealing.}
For the second part of our results, we present a locality-guided work-stealing algorithm that improves the data locality
of multithreaded computations by allowing a thread to have an affinity for a processor. Our initial experiments on iterative
data-parallel applications show that the algorithm matches the performance of static-partitioning under traditional work loads
but improves the performance up to 50% over static partitioning under multiprogrammed work loads. Furthermore, locality-guided
work stealing improves the performance of work stealing up to 80%. 相似文献
110.