黄土高原梯田质量评价系统设计研究   总被引：4，自引：0，他引：4       下载免费PDF全文

陈勇  刘京  刘举 《干旱地区农业研究》2007,25(6):227-230

针对黄土高原的自然环境条件，提出了梯田质量评价的指标体系、评价系统的设计原则及方法。探讨了梯田质量评价系统的主要模块，研究了梯田数据库的结构及主要内容，利用VisualBasic6．0与MapX5．0相结合，开发了黄土高原梯田质量评价信患系统，实现了属性信息与空间信患的相互查询、统计分析以及对梯田质量进行评价。本系统的建立能够对梯田建设与管理提供科学依据，为黄土高原水土保持工作提供基础资料，具有一定的社会和经济效益。  相似文献   

SCARA并联机构拓扑分析与其低耦合度机型设计     

李菊  曾氢菲  沈惠平  杨廷力 《农业机械学报》2017,48(11):405-416

根据基于方位特征(Position and orientation characteristics,POC)的并联机构拓扑结构设计理论与方法,首先,对已提出的一类7个具有较好实用价值的SCARA并联机构,进行了拓扑结构分析,揭示了其POC集、自由度(含驱动副选取)、过约束数、耦合度以及输入-输出运动解耦性等5个最主要的拓扑特征,且发现这些机构的耦合度均较大,为2,表明其运动学正解和动力学求解十分复杂;继而基于机构拓扑结构降耦原理,又对κ=2的这7个机构进行了拓扑结构降耦优化,得到了低耦合度(κ=1),而机构POC、自由度(Degree of freedom,DOF)等保持不变的实现SCARA运动的14个新机型,不仅丰富了实现SCARA运动的4-DOF三平移一转动机型库,而且降低了这些机构的运动学和动力学代数求解难度,而其数值解可用一维搜索法方便求得,从而为这一类SCARA并联机构的运动学和动力学分析、设计及应用提供了理论基础。  相似文献   

Effects of AMF inoculation on growth of Panax ginseng C.A. Meyer seedlings and on soil structures in mycorrhizosphere     

Eun Ju Cho  Do Jin Lee  Chi Do Wee  Hong Lim Kim  Yong Hwa Cheong  Ju Sik Cho  Bo Kyoon Sohn   《Scientia Horticulturae》2009,122(4):633-637

We aimed to investigate the effects of inoculating Panax ginseng C.A. Meyer seedlings with arbuscular mycorrhizal fungi (AMF) by examining the root colonization, plant nutrition uptake, growth characteristics, and soil aggregation of P. ginseng seedlings inoculated at the time of transplantation. At 16 weeks, the AMF spore density per 30 g of fresh mycorrhizosphere in seedlings inoculated with AMF (AMF+ seedlings) was 256.8 and that in seedlings not inoculated with AMF (AMF− seedlings) was 186.3, respectively. The colonization rate of AMF in the lateral roots of AMF+ seedlings was approximately 19% higher than that in the lateral roots of AMF− seedlings. The patterns of AMF colonization in ginseng roots were similar to those of the Paris-type mycorrhizal association. Plant growth characteristics, such as plant height, root length, leaf area, number of lateral roots, fresh weight of shoots and roots, and chlorophyll content, were significantly enhanced in AMF+ seedlings compared to AMF− seedlings. The macronutrient content (P, K, and Ca) and micronutrient content (Cu, Fe, and Zn) of both shoots and roots were also significantly higher in AMF+ seedlings compared to AMF− seedlings. Furthermore, glomalin content and soil aggregation were significantly enhanced in AMF inoculated areas. Our results indicate that AMF inoculation may enhance the growth of ginseng seedlings by improving the uptake of mineral nutrients and the soil structure in mycorrhizosphere.  相似文献   

变量筛选方法对郁闭度遥感估测模型的影响比较   总被引：2，自引：0，他引：2  

琚存勇  邸雪颖  蔡体久 《林业科学》2007,43(12):33-38

比较基于偏最小二乘回归的Bootstrap方法与传统的平均残差平方和(RMSq)准则所选变量建立模型的精度差别.结果表明:Bootstrap方法是一种更优秀的变量筛选方法,比RMSq方法精度提高约5%;而且它不受变量多带来的运算困难的限制,更便于实际应用.  相似文献   

应用PCR诊断隐孢子虫病   总被引：14，自引：4，他引：10  

李建华  张西臣等 《中国兽医学报》1999,19(5):476-478

应用聚合酶链反应（ Ｐ Ｃ Ｒ）建立了一种诊断人及牛等哺乳动物隐孢子虫病的方法。试验采用甘油漂浮 Ｇ３ 耐酸漏斗过滤法纯化隐孢子虫卵囊，以液氮冻融法制备模板 Ｄ Ｎ Ａ，根据隐孢子虫 １８ Ｓｒ Ｒ Ｎ Ａ 序列设计 Ｐ Ｃ Ｒ 引物建立其诊断方法。该方法特异性强，可检出鼠隐孢子虫（ Ｃｒｙｐｔｏｓｐ ｏｒｉｄｉｕｍ ｍ ｕｒｉｓ）和小球隐孢子虫（ Ｃ．ｐａｒｖｕｍ ）卵囊；敏感性高，每克粪便可检出 ４００ 个卵囊。初步应用结果表明，所建立的 Ｐ Ｃ Ｒ 方法适合于人、牛等哺乳动物隐孢子虫病的临床诊断和流行病学调查。  相似文献   

对乙酰氨基酚对大鼠原代肝细胞的损伤机制     

鞠雷  王宝杰  马玉忠 《勤云标准版测试》2008,(11)

胶原酶两步灌流法获取SD大鼠的原代肝细胞,并用不同剂量的对乙酰氨基酚处理.MTT法测定肝细胞的存活率,分光光度法测定培养上清液中乳酸脱氢酶(LDH)的含量.Western blotting法测定大鼠肝细胞中细胞色素P450酶2E1(CYP2E1)的表达水平.结果表明,对乙酰氨基酚可导致肝细胞存活率降低,LDH含量显著升高,CYP2E1表达增加.说明达到一定的剂量时.对乙酰氨基酚可引起肝细胞的损伤.  相似文献   

贮藏期间板栗呼吸特性研究     

王雁萍  戴桂馥  吴健  李宗伟  秦广雍  苏明杰  武广  胡国驹 《果树学报》2000,17(4):282-285

对板栗贮藏期间呼吸速率及影响因素的研究发现：０－５℃贮藏能显著抑制板栗呼吸，能使板栗缓慢呼吸的稳定期延长至次年 ３月，但随贮期延长板栗组织愈加不耐受低 Ｏ２高 ＣＯ２环境；降低起始Ｏ２或提高起始 ＣＯ２浓度不能降低板栗的呼吸速率。  相似文献   

气候变化对中国东北地区生态与环境的影响     

居煇  熊伟  许吟隆  林而达 《勤云标准版测试》2007,(4)

【研究目的】综述了气候变化对东北地区的影响,以期在区域发展中能利用气候变化的有利方面,降低其不利的影响;【方法】根据近年来发表的相关论文,文章综述了东北地区已经发生的气候变化影响及未来可能受到的影响;【结果】结果表明,过去100年东北地区的温度升高明显且降水普遍减少,干旱化趋势严峻。温度的升高改善了东北的热量资源,部分农业生产从中受益。但由于气候变化,目前特殊的生态系统如湿地,冻土退化或消失。未来的气候变化,会改变农业生产布局,降低主要作物的产量,生态系统结构发生改变,农牧带沙漠化的风险增加;【结论】东北地区必须客观认识气候变化的利弊影响,采取相应的适应和应对措施,促进区域发展。  相似文献   

猪脓肿引发大网膜脐疝的手术治疗     

鞠险峰 《贵州畜牧兽医》2008,32(3)

2006年5月,贵州省余庆县白泥镇子营社区草坪三组张某饲养的1头60 kg重架子猪脐部脓肿,请人用针穿刺两次,均有血脓流出,未见好转,求诊,笔者决定手术摘除,现报告如下。1临床检查脓肿直径约10 cm,触摸硬实,表面红肿、发烫,反复触摸无疝轮,穿刺流脓。2手术处理(1)保定:右侧卧保定。  相似文献   

Role of p38 MAPK in cyclic mechanical stretch induced HMGB1 expression in alveolar macrophages     

DING Ning  XIAO Hui  GAO Ju  XU Li-xin  SHE Shou-zhang 《园艺学报》2009,25(10):1979-1982

AIM: To investigate the role of p38 mitogen-activated protein kinase (MAPK) in cyclic mechanical stretch induced the expression of high mobility group box 1 protein (HMGB1) in alveolar macrophages (AMs). METHODS: AMs were cultured and seeded at 1×108 cells/L in 6-well Bioflex cell culture plates. Subsequently, the cells were exposed to cyclic mechanical stretch at 20% (group B) elongation using Flexercell 4000T cell stretching unit. In group C, cells were pre-treated with SB203580 (40 μmol/L) for 2 h before mechanical stretch. Group A served as control. The expression of HMGB1 mRNA in alveolar macrophages was detected by RT-PCR. p38 MAPK activity and the expression of HMGB1 protein were measured by Western blotting analysis. RESULTS: The expression of HMGB1 mRNA and protein, and the activity of p38 MAPK in AMs were significantly increased in group B than those in group A (P<0.05). SB203580, an inhibitor of p38 MAPK, significantly inhibited the inducing effect of mechanical stretch (P<0.05). CONCLUSION: Mechanical stretch regulates the expression of HMGB1 mRNA and protein in alveolar macrophages by activating p38 MAPK signal pathway.  相似文献