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11.
Ivan Hrivňák 《International Journal of Pressure Vessels and Piping》1985,20(3):223-237
This paper deals with the metallurgical changes which occur during heat treatment of welded joints. Stress relieving heat treatment in the temperature range below A1, the normalizing heat treatment and the heat treatment in the intercritical range A1–A3, are all considered. The thermal regime of welding is described. The practice of intercover of the weldment before applying PWHT to ambient temperature is described. It is stressed that the aim of stress-relieving heat treatment is not only to relax internal stresses but also to improve the microstructure and impact properties of HAZ and weld metal, to improve dimensional stability and increase resistance against stress corrosion. Examples are given of the effect of annealing in the intercritical range A1–A3 on the improvement in toughness of electroslag welded joints. Changes in dislocation distribution and density, precipitation processes and grain sizes during PWHT are described. 相似文献
12.
Torshin Ivan Y.; Weber Irene T.; Harrison Robert W. 《Protein engineering, design & selection : PEDS》2002,15(5):359-363
Empirical criteria for identification of hydrogen bonds wereanalyzed to produce a set of geometrically consistent criteria.For a data set of 30 structures, application of a set of purelygeometrical criteria, along with exclusion of abnormal backboneconformations, also excluded a common interaction of Ser/Thrside chains with Asp/Glu side chains ([ST]/[DE] pairs). Theseinteractions were termed `bifurcated hydrogen bonds/', whichimplies delocalization of a positively charged hydrogen of hydroxylbetween the two acceptor atoms of the carboxylic group. These`bifurcated/' interactions are among the most common packingpatterns for [ST]/[DE] pairs of side chains. Therefore, theidentification of hydrogen bonds cannot be based on geometricalcriteria only and requires introduction of some physico-chemicalcriteria. 相似文献
13.
We present an Extended Quadratic Frobenius Primality Test (EQFT), which is related to the Miller-Rabin test and to several
other known probabilistic tests. EQFT takes time equivalent to about two or three Miller-Rabin tests, but has a much smaller
error probability, namely 256/331776t for t iterations of the test in the worst case. We also give bounds on the average-case behaviour of the test: consider
the algorithm that repeatedly chooses random odd k bit numbers, subjects them to t iterations of our test and outputs the
first one found that passes all tests. We obtain numeric upper bounds for the error probability of this algorithm as well
as a general closed expression bounding the error. For instance, it is at most 2-155 for k = 500, t = 2. Compared with earlier similar results for the Miller-Rabin test, the results indicate that our test in
the average case has the effect of nine Miller-Rabin tests. We also give bounds for the error in case a prime is sought by
incremental search from a random starting point. 相似文献
14.
Jose Ivan Escalante-Garcia Victor M. Palacios-Villanueva Alexander V. Gorokhovsky Guillermo Mendoza-Suárez Antonio F. Fuentes 《Journal of the American Ceramic Society》2002,85(7):1788-1792
Mortars of blast furnace slag blended with a geothermal silica waste at various replacement levels of 0%, 5%, 10%, 15%, and 20% were cured for up to 90 days. The binder was activated by 6 wt% Na2 O equivalent of sodium hydroxide. Lime was added as an activating agent and also to promote pozzolanic reaction with the silica. It was found that the presence of the silica waste increased the reactivity of the cementitious materials, as measured by means of nonevaporable water. The compressive strength was increased in the presence of the silica, except at the highest replacement level of 20%, the optimum silica replacement was that of 5%–10%. The microstructures of blended slag showed less porosity than those of neat slag mortars. The lime was completely consumed after 90 days of hydration. 相似文献
15.
The present work is to study the possibility for controlled distribution of the impurities when they are decomposed by sulphuric acid to wet phosphoric acid and phosphogypsum, as well as generating technological conditions for production of clean wet phosphoric acid and its derivatives - phosphoric fertilizers, food phosphates and other phosphoric products.A coefficient of distribution DA is introduced as a general criterion for elements dispersion. The study includes relationships between the weight ratio sulphuric acid/natural phosphate and DA; the period of decomposition and DA; the particle's size content of the natural phosphate and DA. The obtained experimental data and relationships about the influence of the above discussed technological parameters on dispersion of more than 23 elements allow for control of that process in wet phosphoric acid and phosphogypsum by selecting specific technological conditions. Thus, depending on the requirements of acid's consumers and procedures for secondary processing of phosphogypsum to end-products, a selective decomposition of the natural phosphates to phosphoric acid and phosphogypsum can be carried out with content of the impurities in those products varying in narrow limits. 相似文献
16.
Cunningham Stacey C.; Corrigan Sheila A.; Malow Robert M.; Smason Ivan H. 《Canadian Metallurgical Quarterly》1993,7(4):246
Assessed the differences between cocaine- and cocaine-plus-alcohol-dependent inpatients along several psychological variables. Of the 144 men that served as Ss, 113 were cocaine dependent and 31 were dependent on both cocaine and alcohol (CD-AD). CD-AD Ss showed significantly more symptoms of depression and anxiety and were more likely to have antisocial and avoidant personality disorders. The CD-AD group scored higher overall on the MMPI clinical scales. Results suggest that patients dependent on both cocaine and alcohol require increased attention to psychopathology during treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
17.
Ivan Cimrák 《Archives of Computational Methods in Engineering》2007,15(3):277-309
The Landau-Lifshitz (LL)equation of micromagnetism governs rich variety of the evolution of magnetization patterns in ferromagnetic
media. This is due to the complexity of physical quantities appearing in the LL equation. This complexity causes also an interesting
mathematical properties of the LL equation: nonlocal character for some quantities,nonconvex side-constraints, strongly nonlinear
terms. These effects influence also the numerical approximations. In this work, recent developments on the approximation of
weak solutions, together with the overview of well-known methods for strong solutions,are addressed.
Author is supported by the Fund for Scientific Research - Flanders FWO (Belgium). 相似文献
18.
Ceilidh Mackie Jana Levison Andrew Binns Ivan O'Halloran 《Journal of Great Lakes research》2021,47(1):145-159
Nutrient export from agricultural land to surface waters is a significant environmental concern within the Great Lakes Basin (GLB). A field-based watershed-scale study was completed to investigate spatial and temporal variations of phosphorus and nitrate to assess nutrient transport pathways and groundwater-surface water interactions in an agriculturally dominated clay plain system. This was conducted in the 127 km2 Upper Parkhill Watershed, near Lake Huron in southwestern Ontario, Canada. Data collection occurred from June 2018 to May 2019 via continuous sensor deployment and discrete sampling of stream water, groundwater, hyporheic zone, and tile drainage water. Samples were analyzed for various nutrient species (total, total dissolved, soluble reactive, and particulate phosphorus, and nitrate-N) to examine the hydrological dynamics of principal transport pathways of agriculturally-derived nutrients. Total phosphorus and nitrate concentrations in stream water ranged from 0.007 to 0.324 mg/L and 0.32 to 13.13 mg NO3?-N/L, respectively. Tile drainage water total phosphorous concentrations varied from 0.006 to 0.066 mg/L. Groundwater total dissolved phosphorus concentrations ranged from <0.003 to 0.085 mg/L. Transport of phosphorus through tile drainage was observed to be greater than through groundwater over the study period. No distinct relationship was observed between nutrient concentrations in the hyporheic zone and the vertical hydraulic gradient within this zone in the studied stream reach. Preliminary correlations were discerned between water quality observations and recognized land management practices. Given the elevated stream nutrient concentrations, these results are consequential for the continual improvement of strategies and programs devised to conserve water resources within the GLB. 相似文献
19.
Ivan Rodero Hariharasudhan Viswanathan Eun Kyung Lee Marc Gamell Dario Pompili Manish Parashar 《Journal of Grid Computing》2012,10(3):447-473
Virtualized datacenters and clouds are being increasingly considered for traditional High-Performance Computing (HPC) workloads that have typically targeted Grids and conventional HPC platforms. However, maximizing energy efficiency and utilization of datacenter resources, and minimizing undesired thermal behavior while ensuring application performance and other Quality of Service (QoS) guarantees for HPC applications requires careful consideration of important and extremely challenging tradeoffs. Virtual Machine (VM) migration is one of the most common techniques used to alleviate thermal anomalies (i.e., hotspots) in cloud datacenter servers as it reduces load and, hence, the server utilization. In this article, the benefits of using other techniques such as voltage scaling and pinning (traditionally used for reducing energy consumption) for thermal management over VM migrations are studied in detail. As no single technique is the most efficient to meet temperature/performance optimization goals in all situations, an autonomic approach that performs energy-efficient thermal management while ensuring the QoS delivered to the users is proposed. To address the problem of VM allocation that arises during VM migrations, an innovative application-centric energy-aware strategy for Virtual Machine (VM) allocation is proposed. The proposed strategy ensures high resource utilization and energy efficiency through VM consolidation while satisfying application QoS by exploiting knowledge obtained through application profiling along multiple dimensions (CPU, memory, and network bandwidth utilization). To support our arguments, we present the results obtained from an experimental evaluation on real hardware using HPC workloads under different scenarios. 相似文献
20.
Modeling guided wave propagation with application to the long-range defect detection in railroad tracks 总被引:2,自引:0,他引:2
Ivan Bartoli Francesco Lanza di Scalea Mahmood Fateh Erasmo Viola 《NDT & E International》2005,38(5):325-334
The aim of this work is to demonstrate the use of a commercial finite element package, ABAQUS EXPLICIT, to model ultrasonic guided waves in structural components. The particular application of interest is modeling the interaction of a broadband vertical bending mode with transverse-type defects in railroad tracks. This topic is part of a broader project on high-speed defect detection in rails by long-range ultrasonic inspections. Reflection coefficient spectra in the 20–45 kHz range are obtained for four different sizes and three different orientations of transverse head flaws. A preliminary study of Lamb waves in a free plate helps drawing modeling guidelines for the rail. 相似文献