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1.
Japanese farmers manage their irrigation water based on their past experiences and preferences, considering such factors as weather and available water (hereafter defined as empirical water management). They elaborately control the intake and drainage rates of their own paddy fields to maintain optimal ponding depths. But these well-managed systems will drastically change because of the decreasing number of farmers. Therefore, it is necessary to clarify if the optimal ponding depth will be maintained within the limits of traditionally-allowed water intake rate from the main river. The first objective of this study was the quantification of actual water use in the paddy fields, resulting from the farmers water management on the basis of their experience. The significance of the present water intake rate under empirical water management was studied for a paddy field command area of about 230 ha. Water intake rates and the water requirements of the whole area were investigated by measuring the flow rate at 17 points of irrigation and drainage canals. Characteristics of the farmers empirical water management were investigated by measuring the hourly changes in inflow and outflow rates for a sub-area using an automatic measurement system, and an inferential method of determining water management patterns for the paddy fields was proposed. The newly-proposed inferential method was introduced in the tank model, which expresses the characteristics of water management in the command area. The Shuffled Complex Evolution Algorithm (SCE-UA) method was used for optimizing the model parameters. It was proven that the model accuracy improved when the farmers empirical water management was taken into account. The optimal amount of water to be applied to the command area was quantified by the simulation. The second objective was to predict the effect of the decreasing number of farmers on future water use conditions. The simulated result indicates the difficulty of maintaining optimal ponding depth for the whole command area when the farmers empirical water management is not maintained. In other words, results indicated that efficient water use requires an automatic water management system or a new pipeline system to replace the farmers present empirical water management.  相似文献   
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Promoting biomass utilization, the objectives of this study were to clarify the spatial distribution of nitrogen, one of the most important fertilizer components in the methane fermentation digested slurry (i.e., the digested slurry), and to establish an effective method to apply spatial-uniformly digested slurry with irrigation water in the rice paddy field. A numerical model describing the unsteady two-dimensional flow and solution transport of paddy irrigation water was introduced. The accuracy of this model was verified with a field observation. The tendencies of the TN simulated in inlet and outlet portions had good agreement with the measured data and the accuracy of the numerical model could be verified. Using the numerical model, scenario analyses were conducted to determine the method for spatial-uniform application of the digested slurry with irrigation water. The simulated results indicated that drainage of the surface water and trenches at the soil surface were effective for spatial-uniform application of the digested slurry with irrigation water in the rice paddy fields. The effect of the trenches was maximized when the surface water of the rice paddy field was drained adequately.  相似文献   
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关于人的胆汁中存在液晶已见报道,有人推测液晶的出现与胆结石有关。我们用正交的偏振光显微镜观察了猪、鸡的胆汁,并将观察结果和人的胆红素结石伴生胆汁及肌同醇结石伴生胆汁的观察结果进行比较,发现了他们的异同之处.从而使我们对胆汁液晶的产生及其性质,以及胆汁液晶和胆结石之间的关系有了进一步的了解.  相似文献   
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The distribution of the main nutrient elements (N, P, K) as well as microelements (Zn, Mn, Cu, Co, Mo) and heavy metals (Pb, Cd, Sn, Cr, and Ni) in various organs of soybean and wheat plants in the full ripeness stage is studied. It is found that the topography of chemical elements in plants depends on their physiological role, concentration, crop species and its yielding ability.  相似文献   
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The principal eyes of jumping spiders have a unique retina with four tiered photoreceptor layers, on each of which light of different wavelengths is focused by a lens with appreciable chromatic aberration. We found that all photoreceptors in both the deepest and second-deepest layers contain a green-sensitive visual pigment, although green light is only focused on the deepest layer. This mismatch indicates that the second-deepest layer always receives defocused images, which contain depth information of the scene in optical theory. Behavioral experiments revealed that depth perception in the spider was affected by the wavelength of the illuminating light, which affects the amount of defocus in the images resulting from chromatic aberration. Therefore, we propose a depth perception mechanism based on how much the retinal image is defocused.  相似文献   
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杨树抗寒抗旱育种的进展   总被引:10,自引:1,他引:9  
系统地回顾了国内外杨树抗寒抗旱育种的成果和进展。可得出以下结论:(1)杨树抗寒抗旱性改良基本上有两个途径:即选择天然杂种和进行人工杂交育种,而且人工杂交的育种成果远远多于选择随机存在的天然抗寒抗旱杂种。(2)白杨派树种的研究和进展远远落后于青杨及黑杨派树种。主要表现在杂交方式简单,以单交方式为主;选用的亲本有银白杨、新疆杨和山杨;在青杨及黑杨派树种的改良中,小叶杨是一个很好的抗寒抗旱亲本;(3)在杂交方式上由简单到复杂、从单交到多交(三交、四交),抗寒抗旱改良和综合改良的效果随着杂交方式的不断复杂而愈来愈好。同时认为:在遗传工程、生物技术蓬勃发展的今天,杂交育种这一古老的方法仍是杨树抗寒抗旱育种最有效和最基本的手段;在已有的抗寒抗旱种质资源基础上,采用杂种作亲本,进行更复杂的杂交方式是创造杨树抗寒抗旱品种的一个重要方向  相似文献   
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本文报导用根段促萌及嫩枝杆插方法进行河北杨成年优树的初繁试验。结果表明,根萌条诱导所需的有效积温(≥5℃)至少在206℃;嫩枝生根所需的有效积温(≥5℃)至少在200℃。根段的萌条均属皮部萌条类型;嫩枝的生根均属皮部生根类型。此试验方法可为河北杨无性系对比及筛选提供良好的优树初繁材料。  相似文献   
10.
The influence of red clover (Trifolium pratense L.) plants on the decomposition of phenanthrene and octadecane in the soil has been studied. Effect of plant root mass on the abundance of hydrocarbondegrading bacteria, the composition of their communities, and the degradation of hydrocarbons in the soil has been revealed. Changes in the taxonomic composition of hydrocarbon-degrading bacteria under the effect of red clover are characterized by an increase in the abundance of species from the genera Acinetobacter, Kaistia, Novosphingobium, Pseudomonas, and Xanthomonas. A positive effect of the studied microbial–plant association on the degradation of octadecane and especially phenanthrene in the soil has been revealed.  相似文献   
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