车辆导航定位系统GPS接收机的原理与研制     

刘剑平 《农业装备与车辆工程》2005,(4):40-43

分析了OEM板和GPS技术原理，介绍了基于OEM板的GPS接收机开发方法，重点阐述了车辆导航定位系统GPS接收机的软、硬件体系结构及研制过程，详细说明了单片机C语言串行通讯原理与程序编制。  相似文献   

Evolutionary characteristics of morbilliviruses during serial passages in vitro: Gradual attenuation of virus virulence     

《Comparative immunology, microbiology and infectious diseases》2016

The genus Morbillivirus is classified into the family Paramyxoviridae, and is composed of 6 members, namely measles virus (MV), rinderpest virus (RPV), peste-des-petits-ruminants virus (PPRV), canine distemper virus (CDV), phocine distemper virus (PDV) and cetacean morbillivirus (CeMV). The MV, RPV, PPRV and CDV have been successfully attenuated through their serial passages in vitro for the production of live vaccines. It has been demonstrated that the morbilliviral virulence in animals was progressively attenuated with their consecutive passages in vitro. However, only a few reports were involved in explanation of an attenuation-related mechanism on them until many years after the establishment of a quasispecies theory. RNA virus quasispecies arise from rapid evolution of viruses with high mutation rate during genomic replication, and play an important role in gradual loss of viral virulence by serial passages. Here, we overviewed the development of live-attenuated vaccine strains against morbilliviruses by consecutive passages in vitro, and further discussed a related mechanism concerning the relationship between virulence attenuation and viral evolution.  相似文献   

串口的调试和软件实现   总被引：1，自引：0，他引：1  

王兆宇  王巍  袁赣南 《森林工程》2003,19(1):41-43

本文对船舶中使用设备的串口通讯的硬件、软件实现和调试进行了深入的讨论 ,虽然用的是船舶中的例子 ,但所述的方法是通用的。  相似文献   

Tropical Timber Trade Flows in P.R. China     

HU Yanjie LIN Fengming SHI Kunshan Research Institute of Forestry Policy  Information  Chinese Academy of Forestry  Beijing  P.R.China 《中国林业科技(英文版)》2007,6(2):62-73

The historical transition of timber distribution pattern in China was presented firstly with main parts of timber flows in China, which included timber markets, timber transport system and regulations of timber transport. Based on the overview on tropical timber flows in China, the trade flows of tropical timber from production and imports of tropical timber to export of tropical timber products were analyzed by vivid illustrations. At the same time, problems in timber trade flows in China were analysed in the end.  相似文献   

Sex change in coral reef fish   总被引：1，自引：0，他引：1  

Masaru Nakamura  Yasuhisa Kobayashi  Saori Miura  Mohamad Ashraful Alam  Ramji Kumar Bhandari 《Fish physiology and biochemistry》2005,31(2-3):117-122

Gonadal differentiation can take many forms in fish, ranging from gonochorism, where individuals directly develop as male or female and finally possess only testis or ovaries at sexual maturation, to hermaphroditism where the same individuals can produce mature male and female gametes at some time in their lives. Hermaphrodite fish are, thus, an excellent model for studying the plasticity of sex determination and differentiation in vertebrates. We have shown that sex steroids play a principal role in sex differentiation and sex change in fish. Our laboratory implements several fish models that undergo sex change from female to male or male to female or in both directions. In this review, we will briefly discuss recent advances in our understanding of the mechanism of sex change in coral reef fish.  相似文献   

大屏幕信息显示系统信息的生成与传输     

杨卫中  蔡振江 《河北农业大学学报》1998,21(3):85-88

讨论在Ｗｉｎｄｏｗｓ环境下生成及传送ＬＥＤ显示屏显示信息的方法，详细介绍了ＤＩＢ图象的格式，以及用ＢｏｒｌａｎｄＣ＋＋ＯＷＬ在Ｗｉｎｄｏｗｓ９５环境下实现ＤＩＢ图像信息获取的编程方法，讨论了Ｗｉｎｄｏｗｓ９５环境下串行通信的实现方法。  相似文献   

烟蚜的空间分布型及抽样技术初步研究     

许卫东 《天津农学院学报》1995,(4)

作者对陕北烟草上发生的烟蚜进行了空间分布型测定,为聚集分布。求得最适抽样数为N=56.91/x 16.21(三为平均每株有蚜数),当临界防治密度为平均每株有蚜5头时,序贯抽样的上、下限为T(n)=5n±7.88n~(1/2)。  相似文献   

利用土壤的序列数字图像技术研究孔隙小尺度特征   总被引：6，自引：1，他引：6  

李德成  Velde B  张桃林 《土壤学报》2003,40(4):524-528

将土壤样品用混有荧光有机染料的树脂浸渍后 ,以 1mm间距连续研磨 ,经过一定的图像转换处理 ,最后以连续数字图像方式对图像孔隙的小尺度特征进行分析。对一种美国耕作黑土和一种法国耕作黄壤的比较研究表明 ,两类土壤在图像孔隙面积、图像孔隙面积变异性、图像孔隙孔径、孔隙连接度、孔隙重叠度以及孔隙流通性等方面均有所差异 ,这与两类土壤不同的有机质含量有关。  相似文献   

使用Java实现GPS接收机的串口通信     

江永真  袁朝春  陈翠英 《中国农机化》2005,(1):58-62

首先简单介绍了GPS接收机串口通信的基本概念．然后详细介绍利用Java Communication API扩展类库(Javax.comm)来实现GPS串口通信的例子，在实例中还结合Map Objects Java Edition开发工具实现了对GPS接收机位置的实时跟踪和显示。  相似文献   

Thermostability profile of Newcastle disease virus (strain I-2) following serial passages without heat selection     

Wambura PN  Meers J  Spradbrow PB 《Tropical animal health and production》2006,38(7-8):527-531

I–2 is an avirulent strain of Newcastle disease virus. During establishment of the I-2 strain master vaccine seed, a series of selection procedures was carried out at 56^°C in order to enhance heat resistance. This master seed is used to produce a working seed, which is then employed to produce the vaccine. These two passages are done without further heat selection; however, it is not known how rapidly and to what extent thermostable variants would be lost during further passage. The study was therefore conducted to determine the effect of passage on thermostability of strain I-2. The virus was serially passaged and at various passage levels samples were subjected to heat treatment at 56^°C for 120 min. The inactivation rates for infectivity and haemagglutinin (HA) titres were assayed by use of chicken embryonated eggs and HA test, respectively. Thermostability of HA and infectivity of I-2 virus were reduced after 10 and 5 passages, respectively, without heat selection at 56^°C. These results suggest that 5 more passages could be carried out between the working seed and vaccine levels without excessive loss of thermostability. This would result in increased vaccine production from a single batch of a working seed.  相似文献