| 1. | The discussion on models for estimating soil erosion rates from caesium - 137 measurements on cultivated land
示踪农耕地土壤侵蚀速率模型的比较研究 |
| 2. | Rains have been poor , and the government ' s disastrous land - reform programme has turned once flourishing commercial farming into subsistence agriculture
雨水非常稀少，并且政府实行的糟糕的土地改革项目也将曾一时繁荣的经济农场成为仅能维持生存的农耕地。 |
| 3. | Compared with jiang ' s regressive model , the soil rates by 137cs tracer is lower about 10 % than that by jiang ' s regressive mode when they has been used to estimate rates of soil loss on runoff plots
因此，在利用~ ( 137 ) cs技术示踪农耕地土壤侵蚀速率时，这四个模型各自计算的土壤侵蚀速率差异较小。在估算径流小区土壤侵蚀速率中各模型与江忠善经验回归模型的结果相差都在10左右。 |
| 4. | For the cultivated study field , the 137cs concentration is relatively uniform within the plough layer . 2 . the difference and sameness among the existing l37cs models have been discussed , and their precision have been validated by comparing with the regressive model of soil erosion
分析了~ ( 137 ) cs示踪农耕地土壤侵蚀速率模型间的异同，并以土壤侵蚀的经验回归模型为参照对~ ( 137 ) cs法计算的土壤侵蚀速率进行验证。 |
| 5. | The paper deals with the main problems of the land resource in sichuan province : both the predominant land form types and the high quality land types make up little share ; not only the photo - temperature productivity but also the land potential productivity need raising ; the quantity of cultivated land , forest land and grazing land averaged to great population is lacking , which indicates that the contradiction between man and land is outstanding ; on the one hand the reserved land resource suitable for cultivation is insufficient , on the other hand the land difficult to cultivate accounts for great share ; the level of land exploitation and utilization is low and the land productivity develops slowly
四川土地资源的主要问题是优势地貌类型占有量少；优质地类比重不大、光温潜力和土地生产潜力的发挥不够；人多地少，人均耕地、林地和牧草地不足，各地类人均占有量极低，人地矛盾十分突出；宜农耕地后备资源贫乏，难利用土地比重大；土地开发利用程度低，土地生产力水平发挥不够。 |
| 6. | We explored the changing trends in agricultural water demands , the changing trends and variability in soil moisture associated with both drought and increased surface runoff in chinese croplands during the last half - century ( 1946 - 95 ) as well as the projected future years ( 2031 - 65 ) , and their impacts on agricultural production
摘要作者进行一项农业用水需求变化趋势之研究，收集包括中国大陆农耕地在干旱及高地表径流量之土壤水分变化趋势与变异幅度和对农业生产冲击，涵盖过去1946 - 1995年之五十年资料及未来2031 - 2065年之预测值。 |
| 7. | The root system of malus toringoides is so developed that it can grow on prior soil and in cracks of rock . like malus transitoria , malus toringoides tolerant to draught and can grow on sunny dry slope , rocks of steep cliffs , barren stone area , roadsides and field sides . malus toringoides was also adapted to habitat shade and can grow normally gorges of hill , and even on sides of brook and river , where water often attack on
变叶海棠根系发达，能穿透坚硬的土层和岩石裂缝，它具有喜光耐旱的特点，在阳坡、凸坡、悬崖峭壁、瘠薄坚硬的石谷子地、道路两旁和农耕地边都能正常生长，与花叶海棠近似；变叶海棠也具有喜湿耐阴的特点，在深山峡谷、甚至在根系长期经受洪水侵袭的溪边、河岸也能正常生长，与陇东海棠近似。 |
| 8. | Abstract : the agricultural cultivated land types are of connected relationship . the evaluation and development of dike field , terrace and sloping field is a developing course from high to low , their benefits have characters from simple to complicatedness and from single to comprehensiveness . by comparative analysis of their benefits , the potential davantage of agricultural cultivated land in hill and gully region was brought up
文摘:黄土丘陵沟壑区农耕地类型具有裙带关系，从沟坝地、梯田和坡耕地的演化与发展来看，具有从高位到低位的时空演化过程，其效益具有由简单到复杂，由单项到综合的迁变过程。 |
| 9. | The results show that the majority of 7be is retained in the top one centimeter of soils , and the concentration of 7be decreases exponentially with soil depth . for the cultivated study field , the depth distribution of 7be is very similar to the undisturbed site when it is n ' t subjected to erosion or deposition . for the undisturbed , there is abroad peak in the 137cs profile close to the surface and the maximum concentration is found circa 2 cm below the surface
~ ( 137 ) cs在未扰动土壤剖面中主要分布在0 5cm范围内，同时在1 3cm的范围出现一个~ ( 137 ) cs的相对富集层，在3cm以下随土壤深度的增加呈指数递减的趋势； ~ ( 137 ) cs在农耕地土壤剖面中主要分布在0 20cm范围内，由于耕作活动的不断扰动~ ( 137 ) cs的剖面分布相对均匀。 |
| 10. | Tropical rainforests are being cut down at the rate of up to 20 million hectares per year through a combination of pressures : the demand for more agricultural land and land for cattle ranching : to supply firewood to the local people and timber to the industrialized world ; and to make way for mining operations
热带雨林正以每年千万公顷的速度被砍伐,这是由于各方面的压力所致:人们需要更多农耕地和放牧用地;为当地人提供柴火,为工业社会提供木材;为采矿作业让路 |
