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991.
Analysis of signature patterns for discriminating fire detection with multiple sensors 总被引:2,自引:0,他引:2
Incorporating intelligence into a fire detector so that it can recognize signature patterns is intended to permit prompt fire detection while allowing the detector to discriminate between signatures from fire and nonfire sources. The primary purpose of this preliminary study is to investigate the patterns of signatures associated with fire and environmental sources using small-scale experiments. We generated products from a wide range of conditions, from flaming or pyrolyzing samples, to heated samples and samples obtained with an atomizer. We also measured gas concentrations, light obscuration, and temperature to characterize the products. By analyzing the data, we identified trends from which an elementary expert system can be formulated to identify the source of the airborne products. Several patterns are evident. The maximum CO2 concentrations achieved during experiments with flaming fires are significantly greater than the maximum CO2 concentrations achieved during experiments with nonflaming fires (pyrolyzing fires, heated liquids, and environmental odors). The nonflaming sources can be identified based on the CO and metal oxide sensor peak measurements. Except for three experiments using pyrolyzing solids, the peak CO concentration is greater—though the Taguchi detector response is less—for nonflaming fires than for environmental sources. Subsequent application of a neural network properly classifies all except one pyrolyzing fire. 相似文献
992.
Online cage rotor fault detection using air-gap torque spectra 总被引:1,自引:0,他引:1
This paper discusses use of air-gap torque spectra as a means of identifying faults in cage rotors. Being dependent on both stator and rotor currents, the torque is very sensitive to faults in the rotor. Through a comparative study using a detailed machine model and the standard dq model, the paper shows that the characteristic frequencies generated by a particular fault are preserved even if the standard dq model is used for estimation of air-gap torque. This is validated through a practical hardware implementation for online spectrum estimation of air-gap torque using TMS320C31, where several faulted cage rotors were used for study. 相似文献
993.
Exergy analysis of renewable energy sources 总被引:2,自引:0,他引:2
Oil crises in the past years made more obvious the dependency of economies on fossil fuels. As a consequence, the need for new energy sources became more urgent. Renewable energy sources could provide a solution to the problem, as they are inexhaustible and have less adverse impacts on the environment than fossil fuels. Yet, renewable energy sources technology has not reached a high standard at which it can be considered competitive to fossil fuels. The present study deals with the exergy analysis of solar energy, wind power and geothermal energy. That is, the actual use of energy from the existing available energy is discussed. In addition, renewable energy sources are compared with the non-renewable energy sources on the basis of efficiency. 相似文献
994.
Martin E. Sneen Kevin S. Cummings Thomas Minarik Jr. Jennifer Wasik 《Journal of Great Lakes research》2009
The nonindigenous mottled fingernail clam, Eupera cubensis is reported from the Upper Mississippi River Basin for the first time. This record represents a significant northern range expansion for the species in the United States. It appears to be presently confined to a 35-km stretch of the Chicago Sanitary and Ship Canal (CSSC), an artificial waterway that connects the Mississippi River drainage to the Great Lakes. Although the introduction of this species to the Great Lakes basin poses uncertain risks to the general aquatic community, the immediate effects of Eupera cubensis on the fauna of the CSSC are expected to be minimal. 相似文献
995.
996.
Ballard CS Thomas ED Tsang DS Mandebvu P Sniffen CJ Endres MI Carter MP 《Journal of dairy science》2001,84(2):442-452
Three corn hybrids, Mycogen TMF94, Cargill F337 (which contains a brown midrib trait), and Pioneer 3861 were compared in a plot trial, an intake trial, and a lactation trial. In the plot trial, the three corn hybrids were planted in replicated 15.2 x 385-m plots. Mycogen TMF94 and Cargill F337 had lower yields of dry matter (DM), higher concentrations of neutral detergent fiber, and higher in vitro true DM disappearance compared with Pioneer 3861. Mycogen TMF94 had a higher yield of DM than Cargill F337 despite having a lower plant population. However, Cargill F337 had a higher in vitro true DM disappearance than Mycogen TMF94. In the intake trial, six individually penned Holstein heifers were blocked and assigned randomly to one of three total mixed rations containing 79% (DM basis) Mycogen TMF94, Cargill F337, or Pioneer 3861 corn silages in replicated 3 x 3 Latin squares. Heifers fed the Pioneer 3861-based TMR had lower DMI than heifers fed Mycogen TMF94 and Cargill F337-based TMR. In the lactation trial, 75 midlactation Holstein cows were blocked and assigned randomly to one of three total mixed rations containing 31% (DM basis) Mycogen TMF94, Cargill F337, or Pioneer 3861 corn silages used in the intake trial. Milk production was highest for cows fed Cargill F337-based total mixed rations. It is concluded from this study that Mycogen TMF94 was higher yielding, but less digestible, and resulted in lower milk production by lactating cows than Cargill F337. In addition, Mycogen TMF94 had higher in vitro true DM disappearance, and similar DM yield and milk production by lactating cows when compared with Pioneer 3861. 相似文献
997.
Comparison of physician based reporting of tobacco attributable deaths and computer derived estimates of smoking attributable deaths, Oregon, 1989 to 1996 下载免费PDF全文
BACKGROUND: Tobacco use prevention programmes need accurate information about smoking related mortality. Beginning in 1989, Oregon began asking physicians to report on death certificates whether tobacco use contributed to the death. OBJECTIVE: To determine the long term comparability of this method of estimating tobacco attributable mortality to estimates of smoking attributable mortality derived from a computer model. DESIGN: For the period 1989 to 1996, we compared mortality resulting from tobacco use reported by Oregon physicians to estimates of smoking attributable deaths (SADs) derived by "Smoking attributable mortality, morbidity and economic costs" software version 3.0 (SAMMEC 3.0), a widely used software program that estimates SADs on the basis of smoking prevalence and relative risks of specific diseases among current and former smokers. MAIN OUTCOME MEASURES: Numbers of deaths, age, sex, and category of disease. RESULTS: Of 212, 448 Oregon deaths during 1989-1996, SAMMEC 3.0 estimated that 42, 778 (20.1%) were attributable to cigarette smoking. For the same 27 diagnoses, physicians reported that tobacco contributed to 42, 839 (20.2%) deaths-a cumulative difference of only 61 deaths over the eight year period. The age and sex distributions of tobacco and smoking attributable deaths reported by the two systems were also similar. By category of disease, the ratio of SAMMEC 3.0 estimates to physician reported deaths was 1.11 for neoplasms, 0.88 for heart disease, and 1.04 for respiratory disease. CONCLUSIONS: Physician reporting provides comparable estimates of smoking attributable mortality and can be a valuable source of data for communicating the risks of tobacco use to the public. 相似文献
998.
Xiaoyan Xia Philip K. Hopke Bernard S. Crimmins James J. Pagano Michael S. Milligan Thomas M. Holsen 《Journal of Great Lakes research》2012
As part of the U.S. Great Lakes Fish Monitoring and Surveillance Program (GLFMSP), more than 300 lake trout (Salvelinus namaycush) and walleye (Stizostedion vitreum vitreum) collected from the Laurentian Great Lakes each year from 2004 to 2009, have been analyzed for total toxaphene and eight selected congeners. The analytical results show fish toxaphene concentrations are quite different among lakes. Between 2004 and 2009, Lake Superior lake trout had the highest concentration (119 to 482 ng/g) and Lake Erie walleye had the lowest concentration (18 to 47 ng/g). Combining these results with the historical total toxaphene data (1977–2003), temporal changes were examined for each lake. Because of different analytical methods used in the previous studies, the historical data were adjusted using a factor of 0.56 based on a previous inter-method comparison in our laboratory. Trend analysis using an exponential decay regression showed that toxaphene in Great Lakes fish exhibited a significant decrease in all of the lakes with t1/2 (confidence interval) of 0.9 (0.8–1.1) years for Lake Erie walleye, 3.8 (3.5–4.1) years for Lake Huron lake trout, 5.6 (5.1–6.1) years for Lake Michigan lake trout, 7.5 (6.7–8.4) years for Lake Ontario lake trout and 10.1 (8.2–13.2) years for Lake Superior lake trout. Parlars 26, 50 and 62 were the dominant toxaphene congeners accounting for 0.53% to 41.7% of the total toxaphene concentration. Concentrations of these congeners generally also decreased over time. 相似文献
999.
A. M. Sheela J. Letha S. Joseph M. Chacko S. P. Sanal kumar J. Thomas 《Lakes & Reservoirs: Research and Management》2012,17(2):143-159
Statistical techniques represent a reliable tool for classifying, modelling and interpreting surface water quality monitoring data, particularly for lakes. The complexity associated with the analysis of a large number of measured variables, however, is a major problem in water quality assessments. Multivariate analysis, such as cluster analysis and factor analysis (FA), was utilized in this study for the analysis of water quality data (including water discharges and 28 water quality parameters) for Akkulam–Veli Lake, a tropical coastal lake system in Kerala, India. This lake is partially divided into two sub‐systems, namely Veli Lake and Akkulam Lake. Akkulam Lake exhibits freshwater characteristics, in contrast to Veli Lake, which exhibits saline water characteristics because of its close proximity to the sea. Thus, studying this lake provides insights into water quality variations in both a freshwater and saline water lake in a tropical region. Water quality patterns and variations in Akkulam–Vela Lake over three seasons, including pre‐monsoon (PRM), monsoon (MON) and post‐monsoon (POM), also were studied, utilizing multivariate techniques. The organic pollution factor played a significant role on lake water quality during PRM. The influence of organic pollution tends to decrease during MON and POM, a particular situation faced by urban lakes in tropical regions. Polluted stretches in a lake system during different seasons can easily be ascertained by hierarchical cluster analysis. Further, the factors affecting a lake system as a whole, as well as for a particular sampling site, can easily be identified by FA. Improved water quality can be observed during POM. Akkulam and Vela lakes exhibit a wide variation in water quality during all seasons, a finding that corroborates a water flow obstruction from Akkulam Lake to Veli Lake because of the bund existing between the two lakes. The location of the bund is identified as the major reason for different hydrochemical processes in A–V Lake. 相似文献
1000.
High resolution CHIRP (Compressed High Intensity Radar Pulse) seismic profiles reveal the presence of two lacustrine sediment drifts located in Lake Champlain's Juniper Deep. Both drifts are positive features composed of highly laminated sediments. Drift B sits on a basement high while Drift A is built on a trough-filling acoustically-transparent sediment unit inferred to be a mass-transport event. These drifts are oriented approximately north–south and are parallel to a steep ridge along the eastern shore of the basin. Drift A, located at the bottom of a structural trough, is classified as a confined, elongate drift that transitions northward to become a system of upslope asymmetric mudwaves. Drift B is perched atop a structural high to the west of Drift A and is classified as a detached elongate drift. Bottom current depositional control was investigated using Acoustic Doppler Current Profilers (ADCPs) located across Drift A. Sediment cores were taken at the crest and at the edges of the Drift A and were dated. Drift source, deposition, and evolution show that these drifts are formed by a water column shear with the highest deposition occurring along its crest and western flank and began developing circa 8700–8800 year BP. 相似文献