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REST2, a high-performance model to predict cloudless-sky broadband irradiance, illuminance and photosynthetically active radiation (PAR) from atmospheric data, is presented. Its derivation uses the same two-band scheme as in the previous CPCR2 model, but with numerous improvements. Great attention is devoted to precisely account for the effect of aerosols, in particular.Detailed research-class measurements from Billings, OK are used to assess the performance of the model for the prediction of direct, diffuse and global broadband irradiance. These measurements were made in May 2003 during a sophisticated radiative closure experiment, which involved the best radiometric instrumentation currently available and many ancillary instruments. As a whole, these exceptional measurements constitute the only known modern benchmark dataset made specifically to test the intrinsic performance of radiation models. Using this dataset as reference, it is shown that REST2 performs better than CPCR2 for irradiance, illuminance or PAR predictions. The availability of the turbidity data required by REST2 or other similar models is also discussed, as well as the effect that turbidity has on each component of broadband irradiance, PAR irradiance and illuminance, and on the diffuse/global PAR ratio. 相似文献
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OAT是对高压法三聚氰胺生产过程中产生的一种副产品的统称,正常生产中三聚氰胺产品中OAT含量一般在200×10-6,若含量过高会引起三聚氰胺产品浊度超标。本文简单概述了意大利欧技公司高压法三聚氰胺生产工艺基本工艺流程,详细阐述了该工艺 OAT 产生和去除的过程,对正常生产中造成高压法三聚氰胺产品 OAT 含量升高的原因进行了分析,通过分析,总结了高压法三聚氰胺生产工艺中防止产品浊度超标操作注意事项。 相似文献
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In a one-year study, the multispecies assemblages of phytoplankton (picoplankton to microplankton) within a drinking water reservoir were counted, determined and evaluated in their size fractions using microscope enumeration (MC). The manual counts were compared with the size evaluation obtained by a light obscuring particle counter (PC) in order to evaluate its use for the monitoring practice of a drinking water reservoir. With this multispecies comparison we present a novel approach for the evaluation of automated counting systems.The picoplankton clearly remained uncounted by the PC even though its lower size limits imply an adequate match. The highest and most consistent count numbers of plankton (nano- and microplankton) and particles were obtained during the spring mass development. However, from the middle of the year onwards, the measured particle concentration surpassed the counted plankton abundances by two- to threefold indicating the rise of seston within the water column. This fraction would be missed if counted solely by MC. Further, the PC consistently undersized the biological counts, but not the minerogenic fraction represented by the manganese oxidising bacteria. Consequently, the rise and decline of Metallogenium bacteria was reliably monitored with the PC.The PC provides additional size information compared to other bulk optical sensors (turbidity, chlorophyll-a). The correlation of particles with probe measurement always exceeded the plankton coefficient, but all combinations of plankton, particle and probe measurement revealed significant linear regressions. However, the redundancy of the chlorophyll-a probes was also shown in order to explain plankton abundances.Our results indicate that background knowledge of the monitored system and cautious interpretation of data is required to allocate and understand automated particle counts. Therefore, only in combination with MC, the PC enables phytoplankton or minerogenic particle counts under frequent real-time monitoring conditions. As such it may serve as a helpful tool for example in critical situations in the management of drinking water reservoirs. 相似文献
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R. S. Dwivedi A. B. Kumar K. N. Tewari 《International journal of remote sensing》2013,34(11):2303-2318
The availability of remote sensing data with improved spatial, spectral and radiometric resolution is now available to fully exploit their potential for a specific application subject to the relative merits and the limitations of each sensor's data. Presented here is a case study where Landsat MSS and TM; and SPOT MLA data for part of the Bijapur district, southern India, which were acquired on the same day, have been evaluated for mapping eroded lands. The approach involves the geometric registration of all three data to a common map grid using tie points and third order polynomial transform; and resampling the MSS and TM data to a 20m by 20 m pixel dimension and radiometric normalization. Thematic maps showing eroded lands were generated on a micro-VAXbased DIPIX system using a maximum likelihood classifier. Accuracy estimates were made for the thematic maps following stratified unaligned random sampling technique, and subsequently, computing overall accuracy and Kappa coefficient. Spectral separability and classification accuracy was maximum from SPOT-MLA data followed by a combination of Landsat MSS band 1, SPOT-MLA band 2 and Landsat TM band 4; Landsat TM, a combination of Landsat MSS, TM and SPOT MLA; and Landsat MSS data. 相似文献
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A simple model has been developed to predict the removal of hydrocarbon fractions from wastewater using sacrificial Al anodes. The model was successfully applied to the interpretation of experimental data obtained in a laboratory electrochemical cell operated in a batchwise manner. The adsorption equilibrium of organic matter on Al hydroxide was modelled using three equations, with the best results obtained using a Langmuir-type equation. The model was able to describe the effects of current density and pollutant concentration on the efficiency of wastewater treatment. Different values were obtained for the parameters depending on the nature of the hydrocarbon suspension. Aluminium hydroxide showed a far higher affinity for the oil/kerosene suspension but exhibited a higher capacity to remove heavy oil suspensions. The removal rates of pollutants were found to depend on the initial concentration and the current density. When the current density was sufficient to destabilise the emulsion, the zeta potential of the clear fraction measured at pH 7.0 became positive. This change was also characterised by a significant reduction in turbidity. Furthermore, the application of higher current densities did not allow further treatment of the water. However, the efficiency of emulsion destabilisation was found to depend on the concentration and current densities that were too low were ineffective. 相似文献
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生活水浊度是水质化验的一项重要指标,本文介绍了生活水浊度连续监测系统的组成和工作原理以及在快速取样分析、加药控制、数据处理等方面的应用情况。 相似文献
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Wen-Yi Shih 《Desalination》2004,169(3):213-221
An experimental system was developed to assess and rank the performance of commercial antiscalants designed to inhibit mineral scale formation on reverse osmosis membrane surfaces. The study focused on calcium sulfate dihydrate (gypsum) precipitation to illustrate an approach to antiscalant ranking based on its ability to retard the observed onset (i.e., induction time) of gypsum crystallization from supersaturated solutions. The experimental method consisted of on-line monitoring solution turbidity rise and calcium ion concentration decline to signal the onset of gypsum crystallization. Significant differences were found among commercial antiscalants with respect to achievable levels of induction time retardation. Moreover, antiscalant effectiveness with respect to dosage also varied significantly among antiscalants. The present approach enables a relatively simple and robust initial screening of candidate antiscalants based on their induction time as a function of the applied dose. 相似文献