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Search Results: 1 - 10 of 35311 matches for " 欧景莉 "
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广西靖西西南桦天然林种子雨的时空动态
郭俊杰, 赵志刚, , 沙二, 林开勤, 曾杰, 徐大平
植物生态学报 植物生态学报 , 2012, DOI: 10.3724/SP.J.1258.2012.00729
Abstract: ?以一片西南桦(Betulaalnoides)天然林和一个西南桦独立单株为研究对象,通过收集散种期内与林分或母树不同距离的种子以及测定风速和风向,研究了西南桦群落和个体水平上种子雨的时空动态及其与风速和风向的关系。结果表明:群落水平上,西南桦种子散布的初始期、高峰期、消退期分别历时11天、32天和40天,而个体水平上则为9天、25天和26天。高峰期内群落和个体水平的散种量分别占其总量的83.1%和68.7%,而且白天的种子雨密度高于夜间;西南桦个体白天种子雨密度最大的时段为12:00–16:00,与此时段内风速较高有关。在个体水平上,距离母树0–30m范围内散落的种子占总散种量的79.6%;而在群落水平上,距离林缘0–45m范围内集中了总散种量的81.2%。西南桦种子散布具有方向性,无论个体还是群落水平上不同方向间种子雨密度差异极显著(p<0.01),与散种期内的主要风向有关;而且种子雨密度与风速亦呈极显著正相关关系。研究结果将有助于揭示西南桦天然更新动态和更新机制,亦为开展西南桦人工促进天然更新提供理论依据。
在随机干扰影响下两种极值調节系统的分析

自动化学报 , 1963,
Abstract: ?本文利用近似法求出两种极值调节系统在随机干扰影响下搜索损耗的数学期望,因而可以在具体条件下比较两种调节器的优缺点.在正态平稳随机干扰下,相关搜索法对较强的输入端干扰是适宜的;反之,在较弱的输入端干扰时,一般步进搜索法比较有利.计算结果也给出了在各种干扰强度下步进法的最佳步长及相关法的最佳搜索信号振幅.这些都是调节器的重要参数.
艺术作品的多义性

东南文化 , 2000,
Abstract: ????本文主要探讨了艺术作品的多义性问题。
石油天然气藏幔汁加氢和碱交代成因的再认识
杜乐天,,光习
地质论评 , 2015,
Abstract: 油气成因问题争论已有多年。本文在过去的无机成因论的基础上,现在再增加一些自己工作和国内外新进展进一步论证石油天然气藏的热液作用成因。此热液是地幔流体(HACONS简称幔汁)在玄武岩事件中沿盆地底部深断裂上涌减压降温的相变产物,通过加氢和碱交代作用形成油气矿藏。
Cloud computing: an introduction
云计算初探*

,廖剑伟,
计算机应用研究 , 2010,
Abstract: This paper first briefly introduced the cloud computing, then presented the typical architecture of cloud computing. After that, it presented different types of cloud computing. Then described the main cloud service providers and their products followed by primary cloud computing operating systems. Also provided insights on issues faced by cloud computing. Finally, concluded with the need for cloud service composition and argued that semantics was the essenced for growth of cloud computing.
速溶即食葛粉酶法工艺及优化
周先汉,,
食品科学 , 2005,
Abstract: ?本文针对目前市售速溶葛粉的冲调糊液凝结块较多、色泽灰暗等缺陷,试用酶法研制速溶即食葛粉。利用普鲁兰酶水解后的葛粉中的支链淀粉的支链变短,水解度增大;扫描电镜(sem)观察可见,酶解淀粉的片状颗粒增加、表面疏松;产品的溶解度增大,速溶性得到较大程度改善。酶解最佳工艺条件为:普鲁兰酶用量4.8pun/g,温度50℃,反应时间2h。
Spatiotemporal dynamics of seed rain in natural forest of Betula alnoides in Jingxi County,Guangxi, China
广西靖西西南桦天然林种子雨的时空动态

GUO Jun-Jie,ZHAO Zhi-Gang,OU Jing-Li,SHA Er,LIN Kai-Qin,ZENG Jie,XU Da-Ping,
郭俊杰
,赵志刚,,沙二,林开勤,曾杰,徐大平

植物生态学报 , 2012,
Abstract: Aims Our objective was to study spatiotemporal dynamics of seed dispersal of Betula alnoides and analyze its correlation with wind speed and wind direction at community and individual levels. Methods Seed dispersal was investigated for a natural forest and an isolated tree of B. alnoides. We set seven sample lines 100 to 355 m long in or around the natural forest. One seed trap was placed every 5 m, and seeds were collected every two days. We set eight sample lines (east, southeast, south, southwest, west, northwest, north, northeast) around the isolated tree. Three seed traps were placed every 5 m from 0 to 50 m and every 10 m from 60 to 150 m, and seeds were collected each day. Wind speed and wind directions were measured at two sites. Seed rain density was calculated. Important findings The seed rain lasted 83 and 60 days at the community and individual levels, respectively. The starting, fastigium and subsiding stages of seed dispersal lasted 11, 32 and 40 days for the community and 9, 25 and 26 days for the isolated individual. Seeds dispersed at the fastigium stage accounted for 83.1% and 68.7% of all seeds collected at the community and individual levels, respectively. Seed rain density was higher during the day than at night, and the highest seed rain density by day occurred at 12:00–16:00. At the individual level, seed rain density decreased with increasing distance from the maternal tree, and 79.6% of seeds were collected in the area of 0–30 m around the maternal tree. Seed rain density at the community level also decreased with longer distance from the forest edge, and 79.6% of seeds were collected in the area of 0–45 m around the forest edge. The seed rain density was significantly different among directions (p < 0.01), which was affected by wind direction. Seed rain density was also positively affected by wind speed (p < 0.05).
均苯三乙酮的合成研究
Study on Synthesis of 1,3,5-Triacetylbenzene
 [PDF]

张精安, 邹训重, 刘亚杰,, 意桃, 程燕芳
Studies in Synthetic Chemistry (SSC) , 2015, DOI: 10.12677/SSC.2015.33009
Abstract:
目的:合成均苯三乙酮。方法:利用甲酸乙酯、丙酮和乙醇钠反应生成不饱和醇钠,然后用弱酸酸化生成均苯三乙酮。结果:成功合成出均苯三乙酮,并通过TLC监测、测定其熔点及质谱和核磁共振氢谱确定其结构。结论:此合成均苯三乙酮的方法操作简单,原料价廉易得,可用于工业上合成较大量的均苯三乙酮。
Objective: 1,3,5-Triacetylbenzene was synthesized. Methods: 1,3,5-Triacetylbenzene was prepared by ethyl formate and acetone reaction with sodium ethoxide and then the producing unsaturated sodium ethoxide solution was acidified with weak acid. Results: 1,3,5-Triacetylbenzene was synthesized and confirmed by TLC, melting point, 13C-NMR and 1H-NMR. Conclusion: The operating method of the synthesis of 1,3,5-triacetylbenzene was simple, cheap and easily available for the raw materials, so it could be used for the industrial synthesis of relatively large quantities.
大豆蚜玻璃管药膜法敏感毒力基线的建立
潘怡,秦正睿,
大豆科学 , 2010, DOI: 10.11861/j.issn.1000-9841.2010.03.0483
Abstract: 以采自吉林长春地区田间的大豆蚜在室内不接触药剂饲养25代以上,利用玻璃管药膜法建立了大豆蚜对新烟碱类、氨基甲酸酯类、拟除虫菊酯类、有机磷类共10种杀虫剂3.5h的敏感毒力基线。结果表明:大豆蚜对这10种杀虫剂的敏感度较高,LC50从小到大依次为:吡虫啉(0.105μg?g-1)、功夫菊酯(0.924μg?g-1)、溴氰菊酯(1.216μg?g-1)、毒死蜱(1.557μg?g-1)、灭多威(1.918μg?g-1)、克百威(3.927μg?g-1)、马拉硫磷(5.125μg?g-1)、辛硫磷(12.551μg?g-1)、氧乐果(13.190μg?g-1)、氰戊菊酯(28.569μg?g-1)。所测得结果可作为敏感毒力基线,并为大豆蚜的抗药性监测提供理论依据。
对构建耕地保护区域补偿机制的设想
张效军,名豪,,刘志坚
农业现代化研究 , 2006,
Abstract: 持续了20多年的快速经济增长,使我国的综合经济实力和人民生活水平有了极大的提高,但同时也面临着耕地数量和质量急剧下降、圈地运动的屡禁不止和我国耕地总量动态平衡变味走形以及经济发展较快地区建设用地指标不足、欠发达地区指标用不完的严峻现实,究其原因主要是市场和政府双重失灵的存在。耕地面积的过速减少将影响我国的粮食安全,社会稳定和生态安全;建设用地指标的严重不足将影响我国经济的进一步发展。如何解决“吃饭”与“建设”的矛盾已成为我国现阶段土地管理工作的重点和难点,需要对现行土地管理制度进行创新——建立耕地保护的区域补偿机制。
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