oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 34 )

2018 ( 582 )

2017 ( 609 )

2016 ( 663 )

Custom range...

Search Results: 1 - 10 of 26548 matches for " 彭天明 "
All listed articles are free for downloading (OA Articles)
Page 1 /26548
Display every page Item
认知环境中一种改进的CSMA接入方法
伟夫,天明
四川师范大学学报(自然科学版) , 2011,
Abstract: 认知无线电技术通过感知无线环境寻求可用频谱资源,进行智能的、动态的频谱接入,打破了传统无线通信系统固定划分频谱资源的方式,从而提高了频谱资源的利用率.结合认知无线电的特点和802.11CSMA/CA,改进了RTS-CTS帧、虚拟载波侦听、回退机制,提出了一种适合认知环境的改进的CSMA接入方法,并分析了此接入方法的性能.
预应力混凝土简支迭合梁在均布荷载下的抗剪性能
梁书亭,潘国华,天明
工业建筑 , 1991, DOI: 10.13204/j.gyjz199104006
Abstract: 本文介绍了预应力混凝土简支迭合梁的抗剪强度试验,分析了在均布荷载作用下迭合梁的正截面变形特点,迭合梁正、斜截面裂缝开展过程和斜截面破坏机理。为了计算均布荷载下梁的抗剪强度,引入了等效剪跨比的概念。推导出了均布荷载作用下预应力混凝土简支迭合梁的斜截面抗剪强度计算公式。
无菌培养条件下8个紫花苜蓿品种的苗期耐盐性研究
湖?,代 锦?,天明
西北农林科技大学学报(自然科学版) , 2010,
Abstract: 【目的】探讨8个紫花苜蓿品种的耐盐性,为盐碱地改良与利用选择适宜的苜蓿品种。【方法】以8个紫花苜蓿品种种子为材料,在组织培养条件下,观测8个品种在不同浓度nacl(ms培养基中nacl浓度分别为0,50,85,120,170mmol/l)胁迫下的发芽率、单株鲜质量、根长、苗高以及游离脯氨酸含量的变化,并对其耐盐性进行综合评价。【结果】低浓度(50mmol/l)nacl处理对紫花苜蓿的萌发和生长具有促进作用;随着nacl浓度(85~170mmol/l)的升高,紫花苜蓿的发芽率和生长受到明显抑制,表现为相对发芽率、相对根长、相对苗高以及相对单株鲜质量明显下降,而游离脯氨酸含量明显升高。8个紫花苜蓿品种耐盐性的综合排序及其得分为“金皇后”(3.095)>“巨人201”(2.467)>“三得利”(2.379)>“阿尔冈金”(2.369)>“保定”(2.077)>“中苜1号”(1.474)>“敖汉”(0.885)>“wl232”(0.310)。【结论】“金皇后”是耐盐性最高的紫花苜蓿品种,适宜在土壤盐碱含量较高的地区种植;而耐盐性最差的是“敖汉”和“wl232”,盐碱地应尽量避免选种这2个品种。
接枝聚合法回收废发泡聚苯乙烯(EPS)的研究
姚明,天明,拓凯,姜志国
- , 2017, DOI: 10.13543/j.bhxbzr.2017.01.006
Abstract: 将一定量的废发泡聚苯乙烯(EPS)溶解在苯乙烯单体中进行自由基悬浮聚合,以过氧化二苯甲酰(BPO)为引发剂,活性磷酸钙(TCP)和聚乙烯醇(PVA)为分散剂,制备了聚苯乙烯(PS)微球。在聚合油相反应液中,随着废EPS添加量的增加,反应液黏度升高,聚合反应搅拌速率和分散剂用量必须随之提高,废EPS的添加量最好不超过苯乙烯质量分数的20%。凝胶含量分析和凝胶渗透色谱(GPC)分析结果表明,聚合反应过程中,体系中发生了均聚、接枝和交联反应,生成的PS微球分子具有线型、支化和交联3种结构类型,并且随着废EPS添加量的增加,产物中凝胶含量先增加后减少;差示扫描量热仪(DSC)和热重分析仪(TGA)结果表明,聚合产物的耐热性能随着废EPS添加量的增加而稍有提高。
Abstract:Waste expanded polystyrene (EPS) was dissolved in styrene and polystyrene(PS) beads subsequently prepared by radical suspension polymerization with dibenzoyl peroxide (BPO) as the initiator, and activated calcium phosphate (TCP) and polyvinyl alcohol (PVA) as dispersants. The results indicated that the viscosity of the reactant solution increased with increasing amount of waste EPS. As a result, the stirring rate and the dosage of the dispersant must be increased. The optimal amount of EPS was found to be 20% of that of styreneor less. Gel content analysis and gel permeation chromatography (GPC) analysis demonstrated that homopolymerization, graft polymerization and crosslinking reactions occurred between styrene and EPS. The molecular configurations of the PS resulting were a mixture of linear, branched and crosslinked types. As the amount of EPS was increased, the gel content of PS first increased and then decreased. DSC and TGA analysis showed that the heat resistance performance of PS beads improved slightly when the amount of waste EPS was increased.
支持向量回归机的光滑函数研究*
熊金志,胡金莲,袁华强,天明,
模式识别与人工智能 , 2008,
Abstract: 光滑函数能将不光滑模型变为光滑模型,改善支持向量机的回归性能和效率.Lee等人用一个光滑函数逼近ε-不敏感损失函数的平方,提出ε-不敏感的光滑支持向量回归机模型(ε-SSVR).本文为求ε-不敏感支持向量回归机的新光滑函数,运用插值函数和复合函数的方法,首先求正号函数的光滑逼近,然后将其复合成ε-不敏感损失函数平方的光滑函数,得到一类新的光滑函数.并从理论上证明该类光滑函数的逼近精度比以往的光滑函数高一个数量级.实验结果表明回归效果得到改善,从而为支持向量回归机提供一类新的光滑函数.
大豆异黄酮对ad大鼠海马pkg和raf-1的影响
蔡?标,代银,汪远金,王?艳,刘长安,宋?睿,天明
食品科学 , 2012,
Abstract: ?目的:通过观察大豆异黄酮(sif)对阿尔茨海默病(ad)大鼠海马组织蛋白激酶g(pkg)和raf-1蛋白的影响,探讨大豆异黄酮治疗阿尔茨海默病作用机制。方法:采用β-淀粉样蛋白(aβ)双侧海马注射建立ad大鼠模型,分组后给予不同剂量大豆异黄酮,morris水迷宫实验观察大鼠学习记忆能力的变化,elisa法测定大鼠海马组织pkg含量,免疫组化sp法观察大鼠海马组织raf-1的表达。结果:大豆异黄酮可改善ad大鼠的学习记忆能力(p<0.05),显著降低ad大鼠海马组织pkg的含量(p<0.05),显著降低ad大鼠海马组织raf-1的表达(p<0.05)。结论:大豆异黄酮可能通过降低ad大鼠海马pkg的含量和raf-1的表达起到治疗ad的作用。
新化合物ZJ10361的除草活性研究
Study on herbicidal activity of innovative compound ZJ10361

徐小燕,天明,伟立,钟良坤,姚燕飞
- , 2017,
Abstract: 为明确对羟苯基丙酮酸双氧化酶(HPPD)抑制剂类新化合物ZJ10361[1,3-二甲基-4-(2-甲基-4-甲砜基-3-(2-对甲苯氧基)乙氧基)苯甲酰基-1H-吡唑-5-基碳酸乙酯]在玉米田的开发应用潜力,对该化合物的除草活性、安全性、选择性、杀草谱和田间药效进行了研究。室内生物测定结果表明,ZJ10361在有效剂量150 g/hm2下对玉米安全性好,而对其他5种供试作物均有不同程度药害;对不同玉米品种之间的安全性有一定差异,其中对糯玉米科糯986安全性最好,其次为杂交玉米掖单13,甜玉米华珍最为敏感。该化合物在目标作物玉米Zea mays与反枝苋Amaranthus retroflexus、鳢肠Eclipta prostrata之间的选择性系数为4.0~4.5,具有较好的选择性;对阔叶杂草的除草活性较高,杀草谱较广,但对禾本科和莎草科杂草除草活性一般。田间试验结果显示,ZJ10361在有效剂量225 g/hm2下对供试玉米安全性好,对玉米田杂草总草防效为86.9%,与对照药剂硝磺草酮有效剂量150 g/hm2处理相比显著性差异。该化合物用于玉米田防除阔叶杂草具有一定的开发潜力。
In order to investigate the potential application value of a novel compound ZJ10361 [1,3-dimethyl-4-(2-methyl-4-methylsulfonyl-3-(2-p-tolyloxy)ethoxy)benzoyl-1H-pyrazol-5-yl ethyl carbonate], the herbicidal activity, safety, selectivity, spectrum of weed control and field trial were studied. The result of greenhouse tests showed that ZJ10361 was safe to maize at the dosage of 150 g/hm2. However, there were some hazard to other crops. There was different safety in three maize varieties, the safety to waxy corn(Kenuo 986) was highest, that to hybrid corn(Yedan13) was the second highest, and that to sweet corn(Huazhen) is the lowest. The selectivity coefficient of ZJ10361 between maize(Zea mays) and Amaranthus retroflexus and Eclipta prostrata was 4.0-4.5, which showed that the compound had good selectivity. ZJ10361 had good herbicidal activity to broadleaf weed, and it’s weeding spectrum was wider. However, it was less effective to grassy weeds and sedges. The field test results showed that at the dosage of 300 g/hm2, the compound is safe, and the total weeds controlling efficacy was 86.9%. The weed controlling was roughly equivalent to mesotrione at dosage of 225 g/hm2. The compound had potentials to be used as maize herbicide for controlling broadleaf weed.
农业科普期刊选题五忌
天明
中国科技期刊研究 , 1992,
Abstract:
反光标线夜间可见度的测量
天明
公路交通科技 , 1995,
Abstract: 道路标线对交通安全非常重要,因此要求标线无论是在白天或在夜间都必须容易识别.
激光技术在检测公路反光标志膜中的应用
天明
公路交通科技 , 1989,
Abstract: 本文主要介绍以He-Ne气体激光管为光源的激光测光仪的测试原理及技术要求.该仪器体积小,重量轻,调试简单,操作方便,可供研制部门和使用部门使用.
Page 1 /26548
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.