浅析多媒体教学在高职“机械制图”中的应用     

彭永忠 《农业网络信息》2009,(7):107-108,111

多媒体是集图、文、声、像于一体的新型教学手段,可对教学内容进行加工处理、显示和重放,并以其三维直观和动态特性深受广大师生的青睐.但其教学容量大、内容多、速度快等,又不利于学生对所学知识的掌握,容易产生厌学情绪.笔者基于多年的教学经验,通过比较多媒体教学和传统教学的优缺点,提出在高职"机械制图"多媒体教学中必须把握"适时、知度、适当"的原则.  相似文献   

WEEE机械处理分离回收的应用     

李晓祥  姜伟民 《林业机械与木工设备》2009,37(2):42-44

阐述了电子废弃物的主要特点和机械回收利用的一些方法，介绍了国内外电子废弃物机械处理的研究现状及其在工业上的应用。  相似文献   

"桂联系列"联合收割机割刀传动机构动力学分析     

唐宾 《农机化研究》2008,(3):75-78

对"桂联系列"联合收割机往复式割刀传动系统采用平衡配重后的动力学问题进行了研究;并应用三维直角坐标确定机构中各构件的位置,建立曲柄、三角摆块、割刀的运动学和动力学方程,得出利用上述方程确定平衡配重的最优位置和最合理质量.  相似文献   

行星轮系传动比的表格计算法     

陈赛克  朱立学 《仲恺农业技术学院学报》2000,13(4):28-32

利用点的速度合成定理，将轮系中各个构件的转速分解成随系杆一起转动的转速和相对系杆转动的转速。通过列表计算得到轮系中各个构件的转速。  相似文献   

无电源控制阀门控制单元力学性能试验研究     

李俊俊  俞国胜  侯孟 《林业机械与木工设备》2008,36(10)

无电源控制阀门是低成本和高自动化节水灌溉系统中的关键元件.主要介绍无电源控制阀门的工作原理,通过试验测定阀门控制元件中湿敏材料的力学性能,进而确定用于实现控制的缓冲和复位弹簧的力学性能参数,为以湿敏材料为控制元件的设计提供依据.  相似文献   

基于Robin界面条件的非重叠区域分解法     

曾金平  叶玉其 《湖南农业大学学报(自然科学版)》2007,34(6)

描述了一个Neumann模型问题,分析其基于Robin边界条件的非重叠型加性区域分解法.在使用可变参数循环的情况下,给出了算法的微分和有限元离散两种形式及其收敛性质.数值结果表明,适当选取Robin参数,可大大加快算法的收敛速度.  相似文献   

Effects of crop management practices on Echinochloa crus-galli and Chenopodium album seed production in a maize/soyabean rotation     

F Perron  & A Légère 《Weed Research》2000,40(6):535-547

Seed production of residual weed populations needs to be taken into account when estimating the long-term impact of low-input agronomic practices. The objective of this study was to measure the effects and interactions of crop, weed control, tillage practice and nutrient source on the seed production of the dominant residual weed species in a maize/soyabean rotation at two sites: Echinochloa crus-galli (L.) Beauv. on a Sainte-Rosalie clay and Chenopodium album L. on a Duravin clay loam. Seed production per unit area was estimated in each experimental unit. Weed seed production was greater under mechanical weed control compared with chemical weed control. In 1997, E. crus-galli seed production reached over 326 000 seeds m^–2 in mechanical weed control treatments, but averaged less than 500 seeds m^–2 in the chemical weed control treatments. Chenopodium album produced in the range of 766 000 and 73 000 seeds m^–2 in mechanical and chemical weed control treatments respectively. Very few or no weed seeds were produced in soyabean under chemical control. Tillage intensity and nutrient source did not affect seed production of either weed species, with the exception that E. crus-galli produced more seeds in chisel than in mouldboard plough tillage in soyabean. Weed control method had more impact on seed production than tillage intensity and nutrient source in a maize/soyabean rotation.  相似文献   

A preliminary histological and ultrastructural study of opercular anomalies in gilthead sea bream larvae (Sparus aurata)     

M. Galeotti  P. Beraldo  S. de Dominis  L. D'Angelo  R. Ballestrazzi  R. Musetti  S. Pizzolito  M. Pinosa 《Fish physiology and biochemistry》2000,22(2):151-157

  相似文献   

FANUC数控车床数据传输故障的分析与解决     

陈龙波 《湖南农机》2014,(8)

文章简述FANUC数控车床数据传输故障的原因分析与解决方法。  相似文献   

Pathological changes,distribution and detection of Brucella melitensis in foetuses of experimentally-infected does     

Mazlina Mazlan  Siti Khairani-Bejo  Hazilawati Hamzah  Nurrul Shaqinah Nasruddin  Annas Salleh  Mohd Zamri-Saad 《The Veterinary quarterly》2021,41(1):36

BackgroundBrucellosis of goats is caused by Brucella melitensis. It is a re-emerging zoonotic disease in many countries due to transmission from domestic animals and wildlife such as ibex, deer and wild buffaloes.ObjectiveTo describe the pathological changes, identification and distribution of B. melitensis in foetuses of experimentally infected does.MethodsTwelve female goats of approximately 90 days pregnant were divided into 4 groups. Group 1 was exposed intra-conjunctival to 100 µL of sterile PBS while goats of Groups 2, 3 and 4 were similarly exposed to 100 µL of an inoculum containing 10⁹ CFU/mL of live B. melitensis. Goats of these groups were killed at 15, 30 and 60 days post-inoculation, respectively. Foetal fluid and tissues were collected for bacterial identification (using direct bacterial culture, PCR and immuno-peroxidase staining) and histopathological examination.ResultsBilateral intra-conjunctival exposure of pregnant does resulted in in-utero infection of the foetuses. All full-term foetuses of group 4 were either aborted or stillborn, showing petechiations of the skin or absence of hair coat with subcutaneous oedema. The internal organs showed most severe lesions. Immune-peroxidase staining revealed antigen distribution in all organs that became most extensive in group 4. Brucella melitensis was successfully isolated from the stomach content, foetal fluid and various other organs.ConclusionVertical transmission of caprine brucellosis was evident causing mild to moderate lesions in different organs. The samples of choice for isolation and identification of B. melitensis are stomach content as well as liver and spleen tissue.  相似文献