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41.
膜孔灌灌施条件下硝态氮迁移分布规律研究 总被引:9,自引:0,他引:9
利用自行研制的膜孔点源入渗装置,测试膜孔灌灌施条件下硝态氮的迁移和分布规律。结果表明:在肥液连续入渗过程中,硝态氮浓度锋运移与水分湿润锋是一致的;随着距离膜孔中心距离的增加,NO3-N含量减小,在湿润锋位置处土壤NO3-N含量急剧减小到本底值;进入再分布过程后,土壤水分运移速度减慢,整个湿润土体内的含水量分布更加均匀;再分布1~7天内,硝态氮含量略有下降,再分布10天后,硝态氮反硝化作用增强,径向处的反硝化作用弱于垂向处,硝态氮含量明显降低。 相似文献
42.
甘肃沿黄灌区设施蔬菜施肥现状及问题分析 总被引:1,自引:0,他引:1
通过问卷调查和室内测试,分析了沿黄灌区设施蔬菜施肥现状。结果表明:种植户在施用有机肥、化肥及灌水方面存在较大的盲目性,有机肥和化肥的投入量同时增加,缺乏平衡施肥的理念。种植区有机肥投入量在52~337t/hm2,化肥折算纯氮肥年平均投入量为1 165~4 865kg/hm2,磷肥(P2O5)年平均投入量为1 079~2 960kg/hm2,钾肥年平均投入量为631~3 321kg/hm2。设施不同土层土壤pH均显著低于农田土壤,土壤电导率则明显高于农田土壤,其中靖远、皋兰、红古设施土壤电导率超过了蔬菜的生育障碍临界值(EC0.4mS/cm)。 相似文献
43.
The quantity of water available for irrigation is getting scarce in many countries and it assumes great importance for assured crop production, especially in view of the erratic behavior of the monsoon. Thus, there is a pressing need to improve the water efficiency of irrigation systems. One-way of improving the efficiency of the irrigation system is reusing the return flow from the irrigation system. This task requires quantification of return flow, which still remains as a grey area in irrigation water management. The estimation of return flow from the irrigation system is usually obtained using thumb rules depending upon the site-specific conditions like command area conditions and soil properties. In this paper, a hierarchical modeling technique, namely, regression tree is developed for return flow estimation. Regression tree is built through binary recursive partitioning. The effective rainfall, inflow, consumptive water demand, and percolation loss are taken as predictor variables and return flow is treated as the target variable. The applicability of the hierarchical model is demonstrated through a case study of Periyar-Vaigai Irrigation System in Tamil Nadu, India. The model performance shows a good match between the simulated and the field measured return flow values. Results of statistical analysis indicated that the correlation coefficients are high for both single as well as double crop seasons. 相似文献
44.
Ajai Singh 《Irrigation and Drainage Systems》2008,22(2):179-188
Drip irrigation system has been one of the technical means to improve water use efficiency. In India, this system is gaining
popularity among fruit growers and in water scarced area but a substantial area is being covered annually under vegetables
crops. One of the major concerns raised by farmers about this system is its economic viability. In present study, the economic
viability of drip irrigation system for growing capsicum crop based on discounted cash flow technique (Net present worth and
Benefit cost ratio) was explored. Eight irrigation treatments were laid under drip with and without plastic mulch. The irrigation
levels were taken as 1, 0.8 and 0.6 of the crop evapotranspiration. The pan evaporation method was used for estimation of
reference evapotranspiration and Water Balance Approach was used for irrigation scheduling. The average amount of water supplied
under treatment VD (100% irrigation requirement supplied with drip) was found to be 415 mm for whole growing season of the
crop. Similarly the amount of water was found to be 332 mm and 249 mm for the treatment 0.8VD (80% irrigation requirement
supplied with drip) and 0.6VD (60% irrigation requirement supplied with drip) respectively. Highest yield was recorded in
case of treatment VD + PM (100% irrigation requirement supplied with drip plus plastic mulch) followed by VD. Yield under
treatments 0.8VD, 0.6VD, 0.8VD + PM and 0.6VD + PM were significant while treatments VD, VF and VF + PM were at par with the
treatment VD + PM. Net Present Worth (NPW) was found to be positive for all the treatments. The highest NPW was obtained under
treatment VD as Rs. 309,734.90 and lowest was in case of 0.6VD + PM as Rs. 144,172.24. The yield per mm of water used was
reported to be at higher side as 35 in both the treatments VD and VD + PM. But the yield per mm of water used was found to
be lowest as 18.07 and 19 in case of VF and VF + PM respectively. 相似文献
45.
46.
The living environment is becoming more and more important,one of the main elements which affect it is noises.This paper takes the Zhonghuafang for example,to research how the whole planning and the designing for the living district affect the control of noises.Applying architectural technology,in order to cut down noises,a sound screen around the site is made and the distinctive constitution for the buildings is designed.The methods of disposing noises are proposed to make sure that the residents of the advanced living district are content with the living environment. 相似文献
47.
This paper describes a role playing planning exercise that has been used for training agriculturists, engineers and agricultural economists for more than ten years. It sets out the objectives and key features of the exercise and the experience that has been gained in its use. The exercise has been found to successfully test and integrate subject matter expertise acquired from formal teaching. It also highlights the multiple and often conflicting objectives of irrigation planning, and the need for full evaluation of alternatives and sound technical judgements under conditions of inadequate data and time pressure. The exercise is also successful in developing professional personal skills such as group working, interviewing and presentation, and is recommended as an effective training aid. 相似文献
48.
分析了节水灌溉现状;以玉米苗期为研究对象,结合黑龙江省旱作农业实际,提出了一种与中耕相结合的灌溉方式,为采用机械化灌溉方法解决作物苗期干旱问题提供参考。 相似文献
49.
J. P. G. Webster 《Irrigation and Drainage Systems》1989,3(3):211-215
This article describes developments in microcomputer and video-disc technology which may be used in the training of managers for irrigation projects. 相似文献
50.
冯田华 《中国农村水利水电》2001,(12):58-61
主要分析了桃林口水库的农业灌溉、工业城市供水的国民经济效益,分别计算出水库单方农业灌溉供水和工业城市供水国民经济效益值。在水利工程经济效益分析方法、理论有新的探索,对类似工程效益分析有一定的借鉴意义。 相似文献