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1.
To enhance the understanding of the behavior and effects of the precipitation of MnO2 particles in the subsurface generated during in situ chemical oxidation (ISCO) using permanganate, laboratory batch experiments were completed to examine the influence that varied reaction matrix conditions have on the generation and properties of manganese oxides. The conditions examined include organic material type and concentration, permanganate concentration, pH, and the presence of calcium (as a representative divalent cation) in solution. Experimental studies included: (1) spectrophotometric examination of permanganate depletion and manganese oxides generation over time during reactions with trichloroethene; (2) scanning electron microscopy analyses of manganese particle morphology; (3) particle size distribution (filtration) characterization studies; and (4) optical particle sizing and numeration studies. Bench-scale, batch experiments were conducted to focus on fundamental chemical properties affecting particle development under varied potential environmental conditions. The amount of manganese oxides particles that develop, grow, and potentially settle as a result of permanganate ISCO of organic contaminants is a function of the particle size and concentration, the time allowed for particle development, and the impact of matrix conditions on the ability of particles to agglomerate. 相似文献
2.
We compare two link analysis ranking methods of web pages in a site. The first, called Site Rank, is an adaptation of PageRank to the granularity of a web site and the second, called Popularity Rank, is based on the frequencies of user clicks on the outlinks in a page that are captured by navigation sessions of users through
the web site. We ran experiments on artificially created web sites of different sizes and on two real data sets, employing
the relative entropy to compare the distributions of the two ranking methods. For the real data sets we also employ a nonparametric
measure, called Spearman's footrule, which we use to compare the top-ten web pages ranked by the two methods. Our main result
is that the distributions of the Popularity Rank and Site Rank are surprisingly close to each other, implying that the topology
of a web site is very instrumental in guiding users through the site. Thus, in practice, the Site Rank provides a reasonable
first order approximation of the aggregate behaviour of users within a web site given by the Popularity Rank. 相似文献
3.
Michelle Abraham 《电子产品世界》2008,(7)
数字视频编码和解码芯片目前需求量很大.在未来几年里,这种芯片的市场将更加强劲地增长.推动这个市场增长的因素有三个:一个是全球范围的从模拟电视向数字电视的过渡,这种过渡将刺激数字接收机和基础设施设备的需求;另一个因素是手机、便携式播放机和汽车内的移动视频功能日益流行;第三个因素是数字视频标准的持续发展将推动对提供高性能芯片的新需求. 相似文献
4.
This report summarizes the panel held at the 109th Annual Convention, American Psychological Association, August 26, 2001, San Francisco. The chair was William Glover and the speakers were Samuel Gerson, Karen Maroda, and Andre Patsalides. The invited symposium was directed at discussing different perspectives related to the presence of desire in the analytic process. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
Williams Paula G.; Wasserman Michelle S.; Lotto Andrew J. 《Canadian Metallurgical Quarterly》2003,22(1):3
In 2 studies, the relation between measures of self-assessed health (SAH) and automatic processing of health-relevant information was investigated. In Study 1, 84 male and 86 female undergraduate students completed a modified Stroop task. Results indicated that participants with poorer SAH showed enhanced interference effects for illness versus non-illness words. In Study 2, 27 male and 30 female undergraduate students completed a self-referent encoding task. Results offered a conceptual replication and extension of Study 1 by confirming the specificity of the relation between SAH measures and automatic processing of health (vs negative or positive general trait) information. These studies provide evidence that individual differences in SAH are reflected in schematic processing of health-relevant information. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
The development of verbal and spatial working memory was investigated with an interference paradigm. Memory spans were obtained from 3 groups (8-, 10-, and 19-yr olds) under 6 different conditions: Two primary memory tasks (1 verbal, 1 spatial) were administered in isolation and in conjunction with 2 versions of a secondary task. The primary tasks required recalling a series of visually presented digits and recalling the locations of Xs in a series of visually presented grids. The secondary tasks required reporting the color of the stimuli as they were presented using either a verbal or a spatial response. Analyses revealed that all age groups showed domain-specific interference (i.e., interference by a secondary task from the same domain as the primary task), but only the 8-yr-olds also showed nonspecific interference (i.e., interference by a secondary task from a domain different than the primary memory task), suggesting that at least some executive functions do not reach adult levels of efficiency until approximately age 10. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
Nutrient availability has long been considered one of the most important factors regulating production of benthic algae in oligotrophic rivers; yet, empirical relationships do not have as wide an application as similar models derived for lentic systems. The aim of this research was to derive empirical relationships between nutrient concentrations and benthic algal abundance and to identify commonalities with other studies to improve our understanding of constraints on algae in oligotrophic rivers. Surveys of physical, chemical and biological attributes of oligotrophic mountain rivers in spring, summer and autumn for 2 years confirmed that small amounts of anthropogenic phosphorus (0.1–5.6 µg/L total phosphorus (TP)) resulted in 4‐ to 30‐fold increases in abundance of benthic algae and benthic macroinvertebrates (BMIs). Algal accrual along a gradient in nutrient availability was not masked by grazing pressure but was positively correlated with abundance of scrapers. Epilithic abundance was highest downstream of anthropogenic nutrient sources in autumn. We concluded that benthic algal abundance in these mountain rivers was weakly correlated with phosphorus availability if light was not limiting but ultimately controlled by temperature and river discharge. Therefore, we recommend more direct measures of nutrient limitation be used to predict changes in ecological integrity at the lower end of the resource gradient. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
8.
Michelle BarraganStephen Woods Howard L. Julien D.B. WilsonRegor Saulsberry 《Combustion and Flame》2002,131(3):316-328
Thermodynamic equations of state are evaluated for the aerospace fuels hydrazine and monomethylhydrazine using Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) formulations. The PR formulation is shown to be the best fit for hydrazine, and the SRK formulation to be the best fit for monomethylhydrazine, based on available critical property data and evaluations of thermodynamic consistency. The adequacy of the differing property data for these fuels in the literature is discussed, and the methodology used to validate the formulations is outlined. The importance of using appropriate real fluid equations of state in thermodynamic safety and hazards analysis of fuel systems is demonstrated by considering an adiabatic compression of gaseous fuels previously postulated in accident scenarios of aerospace propulsion systems. Calculation of isentropic compression temperatures for pure components using ideal gas constant heat capacity, ideal gas with variable heat capacity, and real fluid equations of state are compared to illustrate the need for real fluid equations of state. In addition, three separate approaches are used for estimating isentropic compression temperatures for mixtures involving these fuels, again illustrating the importance of treating these mixtures as real fluids for design and safety analysis. 相似文献
9.
The prediction capabilities of simple whiteness formulae based on photometer reflectance readings (A, G, B) as compared to linear formulae with adjustable parameters based on chromaticity values (x, y, Y) have been investigated. For each formula, the instrumentally determined whiteness was compared with visually estimated whiteness using the plates of the Ciba–Geigy Plastic White (CGPW) Scale as a standard. This was carried out for a set of 48 fluorescent cotton cloth samples previously studied, as well as for a new set of 86 non–fluorescent cotton cloth samples. As expected, the AGB formulae were inferior to those based on chromaticity values; however, the Taube formula performed quite well for fluorescent samples. On the set of non–fluorescent samples, a formula having green hue preference was required; the Berger formula was found to be the most successful among the simple AGB formulae. 相似文献
10.
Michelle?A.?Phipps Andrew?F.?A.?HoadleyfEmail author 《Korean Journal of Chemical Engineering》2003,20(4):642-648
Heat integration techniques can be used to optimize the energy requirement for both new and retrofit plant designs. Software
tools for identifying retrofit options are becoming available. This paper reports our experiences from using heat exchanger
network (HEN) optimization software for a retrofit case study of an oil refinery process. The HEN optimization software was
used to automate the search for the most beneficial retrofit designs following the twostage process proposed by Asante and
Zhu. The software provided three potential retrofit designs. Results from this analysis were used as the basis of a rigorous
mass and energy balance simulation of the plant. The simulation corroborated the energy savings, but there were some important
differences. The simulation required 20% more heat exchange area. Furthermore, the retrofit design involving one topology
change was shown to be less economic than an alternative design. These differences are discussed and a revised methodology
is proposed. 相似文献