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21.
中国佛手瓜资源调查初报 总被引：6，自引：0，他引：6
佛手瓜是珍贵的蔬菜资源，国外称之为“超级蔬菜”。通过对我国佛手瓜资源的调查，初步查明了佛手瓜在我国的分布、来源及主要品种类型，观测了植物学性，探索了我国佛手瓜栽培技术关键。 相似文献
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23.
电信专业英语教学探讨 总被引：1，自引：0，他引：1
本文针对电信专业英语教学中存在的各种问题,提出了培养学生运用英语能力的若干方法:主讲教师要选择“网络教材”;专业英语教学要与毕业设计、求职和科研结合起来,通过选题、查资料、翻译等形式,使学生的专业知识和专业英语的运用能力得到提高。 相似文献
24.
As an ecologically sustainable aquaculture mode, the rice‐fish approach has been paid more attention in recent years. In rice paddies, there are plant and animal diet items available to fish, but it is not clear how common carp adapt to different diets. In view of this, common carp (initial weight 492.6 ± 30 g, n = 270) were randomly divided into three groups and fed with earthworms (group A), earthworms + duckweed (group M) and duckweed (group P) respectively. After 8 weeks under these feeding regimes, the intestinal digestive enzymes activities were assayed, and intestinal tissue sections stained with HE and AB‐PAS were used to observe the morphology. The results showed that the activities of trypsin and lipase were highest in group A, followed by group M and group P. Group A had greater intestinal fold height, fold width and fold absorption area than the other groups (p < .05), especially in the foregut. Meanwhile, the total number of mucous cells was largest in group P, followed by the groups M and A. Totally, activities and distributions of digestive enzymes, fold height, fold width, fold absorption area and number and distribution of mucous cells of common carp were affected by the type of diet. Based on these results, it was found that common carp has strong adaptability to diets, and it was speculated that the majority of digestion and absorption of protein was concentrated in the foregut, while for starch and cellulose, it was spread out along the whole intestine. 相似文献
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26.
Many industrial products are made of cord-rubber composite materials. Their mechanical behavior not only depends on rubber but also depends on cord. Nylon 66 cord is one of the most important reinforcement in these products. This paper research the mechanical behavior of nylon 66 cord under various load cases. A series of experiments were carried out to obtaining stress-strain curves under different load cases. Complex changes of the modulus and Mullins effect can be found in monotonic and cyclic tension, respectively. Mechanism of these behaviors has been analyzed considering both the twisted structure and material. A phenomenological constitutive model, accounting for different loading conditions, has been firstly proposed base on strain energy density function and damage mechanics method. The proposed model has been verified by comparing the predicted results with experimental data. It has been found that the proposed model predicted the stress-strain curves that were consistent with the experimental data. The proposed model can be implemented in finite element software for engineering design and application. 相似文献
27.
油罐中石油及其液体产品的平均温度测量不准,将直接影响着液体体积的测量精度。从油罐储量对温度测量的要求出发,介绍了铜热电阻平均温度传感器的结构,通过理论分析,指出了提高精度的途径。 相似文献
28.
Li Lingling;Zhang Renzhi;Luo Zhuzhu;Liang Weili;Xie Junhong;Cai Liqun;B. Bellotti 《国际水土保持研究(英文)》2014,2(1):78-90
Rain-fed (dryland) farming is an ancient agricultural production system in China. It occurs widely across almost the whole country, especially in the Northwest and North China. The semi-arid Loess Plateau is the most important region of rain-fed farming in China, but unfortunately, soil erosion on the Loess Plateau area is the highest in China, and indeed amongst the highest in the world. This highlights the necessity for developing practices that can reduce soil and water erosion, improve soil water use efficiency, improve crop productivity, and reduce rural poverty in the region. Many techniques of soil and water conservation are being used in rain-fed areas of China, including such systems as mulch, ridge and furrow systems. The Appendix describes a unique system of soil and water conservation, called Shatian.Modern research on conservation tillage (No Till), although essential for reducing erosion, increasing crop productivity, and ameliorating poverty, is just beginning in China. Modern conservation tillage research started in the1990s' with support from Australia and other countries. The procedures, however, were modified to be in accord with local conditions and prevailing farmer experiences. With 10 years of experimentation, results show that the most successful conservation practice on the Western Loess Plateau is no till with stubble retention. This technique helps to conserve soil water, increases soil organic carbon, improves soil structure and water infiltration, reduces soil and water erosion, and improves crop productivity and sustainability of rain-fed farming systems. However, its adoption rate remains low due to barriers such as traditional attitude, insufficient rural extension, and so forth. 相似文献
29.
分别采用组织块法和消化法2种接种方法进行银狐垂体细胞系构建研究。在消化法中使用不同浓度的胰蛋白酶来检验效果,同时在原代培养期使用反复差速贴壁法纯化,传代培养期结合使用反复差速贴壁以及两步消化法进行处理。结果表明：组织块法接种后成纤维细胞生长明显,原代培养后期成纤维细胞已为主要细胞;降低胰蛋白酶浓度能降低对细胞损伤,但消化时间会增长;采用消化法接种在抑制成纤维细胞生长方面效果好于组织块法。纯化效果上,结合反复差速贴壁法与两步消化法处理后获得了较好的效果,在原代培养时期能较好去除成纤维细胞并通过持续使用该方法可在传二代后获得较高纯度的细胞,纯度能达到80%以上,能够建立细胞系。 相似文献
30.
旧院黑鸡蓝壳蛋的品质研究 总被引：1，自引：0，他引：1
旧院黑鸡蓝壳蛋的比重（４．９９），胆固醇含量（６．３３ｍｇ／ｍｌ）均极显著高于伊莎褐蛋，蛋重（５２．４ｇ）极显著小于伊莎鸡蛋，哈夫单位（８８．１８）显著高于伊鸡蛋，蛋形指数（１．３７）和蛋壳厚度（０．３１７６ｍｍ）与伊莎鸡蛋无显差异。旧院黑鸡蓝壳蛋和白壳蛋与农村散养的科白鸡白壳蛋的蛋重，比重，哈夫单位，蛋形指数等无左异。旧院黑鸡蓝壳蛋和散养科白鸡白壳蛋白壳蛋的胆固醇含量无显著差异，但极显著高于旧院 相似文献