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991.
992.
993.
介绍了古建筑木构件勘查中常用的无(微)损检测技术,阐述了各种仪器工作原理、检测方法及其优缺点,其中包括皮罗钉、阻力仪、应力波和超声波检测设备。基于以上技术,结合古建筑木构件特点,提出仪器结合使用、构件分类检测、设备便携化以及以树种鉴定为基础的木结构古建筑无损评估体系。Abstract: Commonly used nondestructive inspection technologies involved in the survey of the wood structures of ancient buildings are introduced and the inspection methods,working principle,advantages and disadvantages of various instruments,including of pilodyn,re 相似文献
994.
995.
简单介绍CAD技术在我国的使用及发展历程,分析我国农业机械行业在使用CAD技术中存在的突出问题,提出使用CAD技术进行农业机械设计的正确方法,以推进我国农机CAD技术向更深层次发展. 相似文献
996.
农村机耕道路是促进农业生产和发展农村经济的重要基础条件.介绍辽宁省山区农村机耕道路现状,分析制约山区机耕道路建设的主要原因,针对存在的问题,提出加强对机耕道路进行管理和养护的有效措施,确保山区机耕道路切实发挥出其作用与效益. 相似文献
997.
以对某款轿车进气噪声优化为例,介绍了如何通过以改变进气管长度的方式,衰减进气谐振器都难以消除的50-100Hz的进气口低频噪声,并通过GT-POWER模拟计算进气系统的插入损失,得到调整进气管长度对进气噪声影响的规律,最后进行实车验证,车内噪声得到良好改善。 相似文献
998.
Xueming Yang Jun Ma Haobing Li Hongxiang Ma Jinbao Yao Chunji Liu 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(4):495-502
Crown rot, caused by several Fusarium species, is one of the most damaging diseases in wheat and barley. Growing resistant varieties has long been recognised as
an integral part in effectively managing the disease. One of the factors hindering the progress of breeding for crown rot
resistance is the lack of a reliable and high throughput bioassay that allows rapid and accurate assessment of large numbers
of genotypes so that highly susceptible materials can be quickly rejected and potentially resistant lines identified for more
focused further assessments. We developed a method which, by growing several inoculated seedlings wrapped in a single piece
of moist paper towel, offers significant advantages over all of the existing methods. The new soil-less assay takes only about
two weeks, requires very little space, and removes variability associated with the use of soil/potting mixes. Results from
the new assay are highly reproducible and agree well with known field performances of different varieties. However, mapping
studies conducted using the new soil-less assay did not detect all of the quantitative trait loci found with a soil-based
assay. These results show that, although different resistance genes may all contribute to the performance of a variety, caution
should be used when comparing results from different assays. 相似文献
999.
As an important digestive enzyme gene, the serine protease gene AlSP 3 plays a key role in Apolygus lucorum for digesting conventional cotton. To understand the effect of different temperatures on the expression level of AlSP 3, we analyzed the expression patterns of AlSP 3 in A. lucorum reared at different temperatures using real-time polymerase chain reaction. The results showed that at the normal temperature of 24 ℃, the expression of AlSP 3 in A .lucorum at different nymphal stages was similar. The expressions of AlSP 3 in the female adult at the pre-mating stage and the male adult at post-mating stage were 19.71- and 7.16-fold higher than their control at the 1st nymphal stage, respectively, which were significantly higher than at any other stages. However, expression in the 4th to 5th A. lucorum at the nymphal stage increased with rising temperature in the range of 21~30 ℃. At 30 ℃, the expression of AlSP 3 in the 2nd to 5th A. lucorum was the highest. The expression levels of AlSP 3 in adult A. lucorum reared at different temperatures during the new emergence and pre-mating stages were significantly higher than that of the control reared at 24 ℃ (P < 0.01), while the expression during the post-mating stage at 18℃ was higher than that at other temperatures. When incubated at extreme temperatures (4 ℃ and 40 ℃), the expression of AlSP 3 in female and male adult A. lucorum was significantly higher than that at 24 ℃ (P < 0.01). Taken together, our results showed that the external environment temperature and the internal stage of A. lucorum or its sex all had significant effects on the expression of AlSP 3 in A. lucorum (P < 0.01), and that there was some interactions between them. Therefore, AlSP 3 is very important for the female adult A. lucorum to obtain nutrition at the early stages and temperature is an important limiting factor for the expression of AlSP 3. 相似文献
1000.
中蜂来源的微孢子虫对意蜂工蜂的侵染性研究 总被引:2,自引:0,他引:2
为探讨中蜂来源的微孢子虫对意蜂的侵染性,本试验将纯化自中蜂的微孢子虫,以每只蜂1×105个和5×105个孢子的接种量,分别给2日、5日、8日、11日龄无微孢子虫感染的意蜂成年工蜂接种,在30℃±0.5℃,65%~80%RH,黑暗中隔离饲养10日后,各日龄工蜂的平均感染率达86.3%~100%,每只蜂中肠的平均产孢量为5.60×105~3.39×106个。在两接种量下,2日、5日龄意蜂工蜂的产孢量均显著(P<0.05)高于8日、11日龄的产孢量。试验首次证实了中蜂来源的微孢子虫对意蜂成年工蜂具较强的侵染性。 相似文献