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191.
水肥模式对温室小型西瓜水分利用及光合特性的影响研究 总被引:3,自引:0,他引:3
通过田间试验,研究不同灌溉模式与施肥方式对设施栽培条件下小型西瓜水分利用、光合特性以及产量品质的影响。研究结果表明,节水灌溉处理W3可在实现节水50%的基础上获得较高的产量,并且糖分测定结果显示,减少灌水对提高西瓜品质也有益处。根据光合特性分析结果,适当范围内控制土壤水分可促进西瓜的光合速率、气孔导度和蒸腾速率,并提高计算水分利用率。不同施肥处理研究结果显示,适当减少氮肥可明显提高西瓜品质,而磷肥处理与西瓜产量品质的关系不明显,需进一步研究。 相似文献
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194.
In arid regions, reductions in the amount of available agricultural water are fueling interest in alternative, low water-use crops. Perennial grasses have potential as low water-use biofuel crops. However, little is known about which perennial grasses can produce high quantity, high quality yields with low irrigation on formerly high-input agricultural fields in arid regions. We monitored biomass production, weed resistance, rooting depth, and root architecture of nine perennial grasses under multiple irrigation treatments in western Nevada. Under a low irrigation treatment (71 ± 9 cm irrigation water annually), cool-season grasses produced more biomass and were more weed-resistant than warm-season grasses. With additional irrigation (120 ± 12 cm water annually), warm- and cool-season grasses had similar biomass production, but cool-season species remained more weed-resistant. Among species within each grass type, we observed high variability in performance. Two cool-season species (Elytrigia elongata and Leymus cinereus) and one warm-season species (Bothriochloa ischaemum) performed better than the other tested species. Root depth was not correlated with biomass production, but species with deeper roots had fewer weeds. Abundance of fine roots (but not large roots) was correlated with increased biomass and fewer weeds. Both L. cinereus and E. elongata had deep root systems dominated by fine roots, while B. ischaemum had many fine roots in shallow soil but few roots in deeper soil. Cool-season grasses (particularly E. elongata, L. cinereus, and other species with abundant fine roots) may be worthy of further attention as potential biofuel crops for cold desert agriculture. 相似文献
195.
Abstract There has been renewed interest during recent times in the impact of irrigation development on rural poverty. For long, researchers asked whether irrigation development reduces the poverty of irrigators. However, the question being asked now is: does investing in irrigation—rather than in other public works—help reduce rural poverty in a region? Using Government of Gujarat's 1997 census of Below Poverty Line (BPL) households as well as the Village Amenity Survey of the same year, this paper explores the interplay between irrigation development and rural poverty in 177 predominantly rural talukas, which is an administrative unit with a population of around 100,000-150,000 people, of Gujarat state in western India. Our analysis shows that for the design of poverty-targeting programs, two variables have the highest appeal: primary education infrastructure and improved land productivity through irrigation. It also suggests that, over the long run, irrigation benefits far transcend the command areas of irrigation systems. As a result, irrigation impact studies focused at farm or command area level seriously underestimate overall livelihood impacts of irrigation development. This is because intensively irrigated areas act as magnets that attract rural poverty from their surround, especially from other dry areas. Population pressure on farm lands thus tends to get redistributed according to the carrying capacity of farm lands. Across 177 predominantly rural talukas of Gujarat, we find: a) an inverse relationship between land use intensity and land-man ratio; and b) as land productivity (output/hectare of net sown area) declines, output per rural person declines too, but far more slowly than would have been the case without the “magnet effect.” 相似文献
196.
Fertigation in Furrows and Level Furrow Systems. II: Field Experiments, Model Calibration, and Practical Applications 总被引:1,自引:0,他引:1
J. Burguete N. Zapata P. García-Navarro M. Ma?kaka E. Playán J. Murillo 《Canadian Metallurgical Quarterly》2009,135(4):413-420
Furrow fertigation can be an interesting practice when compared to traditional overland fertilizer application. In the first paper of this series, a model for furrow fertigation was presented. The simulation model combined overland water flow (Saint-Venant equations), solute transport (advection-dispersion), and infiltration. Particular attention was paid to the treatment of junctions present in level furrow systems. In this paper, the proposed model is validated using five furrow fertigation evaluations differing in irrigation discharge, fertilizer application timing, and furrow geometry. Model parameters for infiltration and roughness were estimated using error minimization techniques. The error norm was based on observed and simulated values of advance time, flow depth, and fertilizer concentration. Model parameters could be adequately predicted from just one discharge experiment, although the use of more experiments resulted in decreased error. The validated model was applied to the simulation of a level furrow system from the literature. The model adequately reproduced irrigation advance and flow depth. Fertigation events differing in application timing were simulated to identify conditions leading to adequate fertilizer uniformity. 相似文献
197.
J. Monserrat 《Canadian Metallurgical Quarterly》2009,135(1):1-6
This article reviews the method for allocating flow to irrigation plots proposed by Clément and Galand in (1979). Mention is made of its shortcomings, such as the lack of consideration given to the specific technical and economic factors governing current pressurized (drip or sprinkler) irrigation systems and how they provide water to plots. We propose a method for fixed irrigation systems, which takes into account the irrigation method on the plot and the existence of an optimum block area. The result is to allocate a constant flow of water to plots up to an established value of maximum surface area. From there on, we propose applying linear increases related to the total plot area. We also present a formula for calculating the maximum number of blocks based on variables that are easily obtainable during the project phase. 相似文献
198.
Field Properties in Surface Irrigation Management and Design 总被引:1,自引:0,他引:1
Theodor S. Strelkoff Albert J. Clemmens Eduardo Bautista 《Canadian Metallurgical Quarterly》2009,135(5):525-536
Field properties—topography, hydraulic resistance, and infiltration—play an important role in the performance of surface irrigation systems, and appropriate characterizations of these are required as data input to simulation or design software. The EWRI/ASCE Task Committee on Soil and Crop Hydraulic Properties has been charged with preparing a guide for practitioners faced with such data entry. The result is this special section of the Journal of Irrigation and Drainage Engineering in which this paper is the first in the series presented. It describes the characteristics of these field properties and notes a series of caveats to be considered when dealing with them in the course of analyses or designs of surface irrigation systems. 相似文献
199.
N. Lazarovitch M. Poulton A. Furman A. W. Warrick 《Journal of Engineering Mathematics》2009,64(2):207-218
An artificial neural network (ANN) technology is presented as an alternative to physical-based modeling of subsurface water
distribution from trickle emitters. Three options are explored to prepare input–output functional relations from a database
created using a numerical model (HYDRUS-2D). From the database the feasibility and advantages of the three alternative options
are evaluated: water-content at defined coordinates, moment analysis describing the shape of the plume, and coordinates of
individual water-content contours. The best option is determined in a way by the application objectives, but results suggest
that prediction using moment analyses is probably the most versatile and robust and gives an adequate picture of the subsurface
distribution. Of the other two options, the direct determination of the individual water contours was subjectively judged
to be more successful than predicting the water content at given coordinates, at least in terms of describing the subsurface
distribution. The results can be used to estimate subsurface water distribution for essentially any soil properties, initial
conditions or flow rates for trickle sources. 相似文献
200.
介绍了基于单片机的节水灌溉控制系统的方案设计,工作原理,硬件电路和软件设计.实践证明,该系统具有成本低、运行可靠、可扩展性好等特点,有广泛的应用价值和前景. 相似文献