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91.
Hugo M. Santos Bruno Pedras Abel Tamayo Jaume Casabó Lluis Escriche Berta Covelo José Luis Capelo Carlos Lodeiro 《Inorganic chemistry communications》2009,12(11):1128-1134
Two new emissive chemosensors based on coumarin-343 have been synthesized, and their photophysical studies conducted. L1 contains an aza-thio macrocycle ring as the chelating unit, which has great affinity for soft metal ions, whereas L2 is a parent species without macrocyclic unit. Both compounds were separated by column chromatography and characterized by elemental analysis, 1H,13C NMR, UV–vis and FAB mass spectroscopy. The X-ray structures of L1 and L2 and the supramolecular interactions in the solid state are discussed. Preliminary results on the metal–ion sensing effects of the ligands are presented. Titrations with Ag+, Pd2+ and Ni2+ have been studied by UV–vis absorption and fluorescence spectroscopy. 相似文献
92.
Hugo Elizalde Mehmet Imregun Ricardo A. Ramírez-Mendoza 《Mechanical Systems and Signal Processing》2009,23(1):87-103
This work introduces a novel theoretical formulation for the evaluation of approximate eigenvalues and eigenvectors for general non-linear MDOF systems using the so-called “approximate non-linear mode evaluation” (ANME) method. The approach is based on analytically derived quasi-linear expressions which relate the change in modal parameters to physical non-linear elements that can be added anywhere in the system. Subject to assuming that the change in the mode shape is small, expressions for non-linear eigenvalues and eigenvectors become fully determined for a general MDOF system, even within typical experimental constraints. The errors arising from this assumption can be minimized via an iterative procedure. Preliminary results indicate that the rate of convergence is quite fast for systems with medium to high damping but more effort is required for lightly damped systems. The derived expressions provide a theoretical basis for observations made by previous researchers from an inspection of their experimental and/or numerical results: these indicate that an invariant relationship exists between a non-linear eigenvalue and its associated modal response. 相似文献
93.
Martin J. J. Jak Robert Caputo Eefje J. Hornix Luciano de Sio Dick K. G. de Boer Hugo J. Cornelissen 《Journal of the Society for Information Display》2008,16(8):803-810
Abstract— A large part of the light generated in a backlight is usually absorbed in the color filters of the liquid‐crystal display. A new backlight system that uses a grating to split the white light into different colors and a lens array to focus this light onto the pixels is presented. The absorbing filters can be eliminated and efficiency is improved. The system is characterized, as well as its different components. 相似文献
94.
This paper outlines the Level 2 portion of a methodology for determining the incremental induced steam generator tube rupture large early release fraction caused by an actual through-wall defect. This defect was responsible for the minor steam generator tube leak that occurred in September 2002 at the Comanche Peak Steam Electric Station Unit 1. In order to quantify the performance of the defect over the operating cycle, a range of defect lengths were input to the PROBFAIL computer code [Kenton, M., 2001. PROBFAIL: A Computer Code for Evaluating the Likelihood of Steam Generator Tube Rupture in Severe Nuclear Power Plant Accidents, CREARE TM-2138], using appropriate boundary conditions derived from MAAP4 [Henry, R., et al., May 1994. MAAP4—Modular Accident Analysis Program for LWR Power Plants, Computer Code Manual, EPRI Research Project 3131-02] runs. From the analysis of the calculated times of burst for each assumed defect length, the minimum through-wall defect length necessary for tube burst to occur prior to hot leg or surge line creep rupture was calculated. The probability that the defect would actually have this length was then estimated by determining the fraction of the cycle for which the defect would be at least that long. The methodology development and implementation relied on MAAP4 runs, which are discussed extensively in connection with their role in: (1) guiding the construction of the accident progression event tree, (2) generating relevant information for probability assignments in the various underlying fault trees and (3) obtaining boundary conditions of pressure and temperature for use in PROBFAIL. The overall increment in LERF due to the existence of the defect was calculated to be approximately 4E−08. 相似文献
95.
Matthew J. Watson Helen M. Chan Martin P. Harmer Hugo S. Caram 《Journal of the American Ceramic Society》1998,81(8):2053-2060
The reaction-bonded aluminum oxide process begins with aluminum, Al2 O3 , and usually ZrO2 powders that have been attrition-milled in an organic liquid. The attrition-milled powder is then compacted and heat-treated in air to produce polycrystalline, Al2 O3 -based ceramics. Safety considerations have made it desirable for the milling liquid to be changed from acetone to a less-flammable solvent. In this paper, mineral spirits, ethanol, and mineral spirits that contains 2 wt% stearic acid are presented as viable alternatives to acetone. The effects of changing the milling liquid on the reaction process and the properties of the final fired ceramic are investigated. 相似文献
96.
Jacomijn Pluimers Carolien Kroeze Evert Jan Bakker Hugo Challa Leen Hordijk 《Nutrient Cycling in Agroecosystems》2001,60(1-3):209-218
In this paper, present-day emissions of greenhouse gases and acidifying compounds from agriculture are analysed at the farm
level. Quantitative estimates are given for these emissions from three nested systems in the Netherlands: the agricultural
sector, greenhouse horticulture, and tomato cultivation under glass. Total emissions are subdivided into emissions from biogenic
sources and abiogenic sources. We conclude that, although most of the emissions from the agricultural sector have biogenic
sources, those from abiogenic sources should not be neglected. Abiogenic emissions are mainly from greenhouse horticulture.
The cost-effectiveness of options to reduce carbon dioxide (CO2) and nitrogen oxides (NOx) emissions from on-farm combustion of natural gas in tomato cultivation under glass is analysed. An inventory is given of
technical reduction options that are presently available in practice. Based on information about the costs and the reduction
potential of each option, cost-efficiency curves are derived for both types of emissions. Relative to a situation where none
of the described options were applied (early nineties), CO2 and NOx emissions from tomato cultivation can be reduced at most by about 70% and 75%, respectively, by combinations of technical
options.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
97.
98.
F. Xavier Malcata Hector R. Reyes Hugo S. Garcia Charles G. Hill Jr. Clyde H. Amundson 《Journal of the American Oil Chemists' Society》1990,67(12):890-910
This review focuses on the use of immobilized lipase technology to effect hydrolysis, ester synthesis, and interesterification
reactions. The various immobilization procedures, reactor configurations, and process considerations are all reviewed and
discussed. 相似文献
99.
Zeev Goldschmidt Dafna Hezroni-Langerman Hugo E. Gottlieb Yizhak Bakal 《Israel journal of chemistry》1990,30(4):385-390
The mechanism of the reactions of (η4-cycloheptatrien-1-al)Fe(CO)3 and its ethyleneglycol acetal with tetracyanoethylene (TCNE) was studied. The aldehyde undergoes a fast reversible 3+2 cycloaddition involving the free aldehyde-substituted double bond, and a slow irreversible 3+2 cycloaddition at the coordinated site. The latter, σ,π-allylic complex undergoes a slow interconversion with the corresponding 5 +2 isomer via the pericyclic [3,3]-sigmahaptotropic rearrangement. In contrast, the acetal reacts with TCNE at the free acetal-substituted double bond to give a single kinetic 3+2 adduct, which, under thermodynamic conditions, undergoes a [4,4]-sigmahaptotropic rearrangement to the 6 + 2 adduct. The reaction kinetics was followed by 1H NMR. The effect of substituents on the reaction course is discussed, and the detailed mechanism of both the cycloadditions and rearrangements is described. 相似文献
100.
Hugo E. Acosta-Martinez Susan M. Gourvenec Mark F. Randolph 《Soils and Foundations》2008,48(2):247-254
Shallowly embedded skirted foundations are an attractive alternative to piles for jacket structures and buoyant facilities as they can resist uplift but are cheaper to install than deep foundations. Bearing capacity of shallow skirted foundations in compression is moderately well understood while there is still considerable uncertainty over uplift capacity, particularly for loading sustained over a period of time. This paper reports results from beam centrifuge tests on a shallow skirted foundation in clay, subjected to uplift and compression. Rapid and sustained loading is considered and the effects of consolidation stress level and stress history on undrained capacity and sustained load response are reported. 相似文献