一种新型集蔗器的结构设计及其有限元分析

集蔗器是甘蔗收割机中用来收集甘蔗的装置。通过总结前人所设计的集蔗器的优缺点,提出了一种新型集蔗机构—挡板式斜集集蔗器,并进行了结构设计、参数计算和三维建模;最后,为了验证所设计的集蔗器转轴的尺寸的合理性,通过有限元分析了软件ANSYS分析它在受外力情况下的变形情况和整体的应力分布情况。     

土壤水分与毛白杨蒸腾耗水关系的研究

以不同水分条件下盆栽苗木和大田幼林为材料，对土壤水分与毛白杨蒸腾耗水的关系进行了分析研究，并建立了蒸腾耗水量模型。结果表明，土壤水分含量与蒸腾耗水量之间呈极显著正相关，且土壤水分状况还影响蒸腾节律；蒸腾耗水量因不同的土壤水分条件、供水历程、气象等因素而具有不同的变化特点。     

β干扰素转基因小鼠的建立和特性研究

选择ICR小鼠为受试动物,应用显微注射仪,将线状人β干扰素基因,按2940～10000拷贝,1～3pL的剂量注射到供体受精卵的雄前核,然后移植到假孕受体的输卵管。实验先后注射了301个受精卵,移植到20只假孕受体,其中5只妊娠,产仔25只。从所获得的25只亲代小鼠的尾组织提取DNA,用内切酶BamHI消化,以[α-~(32)P]-dCTP标记的上述外源基因为特异性核酸探针,应用DNA印迹法检测这些小鼠DNA内外源基因的整合状况.结果表明,亲代小鼠中有人β干扰素基因重组子的转基因小鼠,杂交带在6.8kb位置。应用上述同样方法对亲代转基因小鼠的子1代组织DNA检测发现,绝大多数小鼠的标本除见到1条1.8kb人β干扰素基因的较弱杂交带外,还有数条5.0kb以上强弱各异的杂交带,表明这种外源基因不仅整合到了亲代小鼠的遗传物质内,而且可经垂直方式传给子代。人β干扰素基因的鼠体水平表达检测发现,1只子1代转基因小鼠的肿瘤组织浸出液中含有人β干扰素,滴度达160U/mL,表明整合在小鼠DNA内的人β干扰素外源基因不经诱导而有一定表达。     

野生日本鸣鹑与家鹌鹑及其杂交后代的行为规律研究

将微山湖野生日本鸣鹑与家鹌鹑杂交F2代按1公∶5母进行分组,采用秒表单位记时法观察鹌鹑的行为,并引用同期亲本和F1代的相同资料,对鸣叫、打斗和交配行为频次进行比较。结果表明:①杂交F2代鹌鹑鸣叫行为比家鹑低,除10∶00～11∶00外,其余时间段均存在显著差异(P<0.05);在14∶00～15∶00与野生日本鸣鹑存在显著差异(P<0.05);在14∶00～16∶00杂交F1代有显著差异(P<0.05);②杂交F2代鹌鹑打斗行为除16∶00～17∶00外与家鹑及杂交F1代无显著差异;③杂交F2代鹌鹑交配行为除16∶00～18∶00外与家鹑及杂交F1代均有显著差异(P<0.05)。     

Characterization and immunogenicity of an apxIA mutant of Actinobacillus pleuropneumoniae

Actinobacillus pleuropneumoniae is the aetiological agent of porcine pleuropneumonia, a highly contagious and often fatal disease. A candidate live vaccine strain, potentially capable of cross-serovar protection, was constructed by deleting the section of the apxIA gene coding for the C-terminal segment of ApxI toxin of the A. pleuropneumoniae serovar 10 reference strain (D13039) and inserting a chloramphenicol resistance gene cassette. The mutant strain (termed D13039A(-)Chl(r)) produced an approximately 48kDa protein corresponding to the N-terminus of the ApxI toxin, and exhibited no haemolytic activity and lower virulence in mice compared with the parental strain. The mutant was evaluated in a vaccination-challenge trial in which pigs were given two intra-nasal doses of the mutant at 14 days intervals and then challenged 14 days after the last vaccination with either A. pleuropneumoniae serovar 1 (4074) or serovar 2 (S1536) or serovar 10 (D13039) reference strains. The haemolysin neutralisation titres of the pre-challenge sera were significantly higher in the vaccinated pigs than in the unvaccinated pigs. The mortalities, clinical signs and lung lesion scores in the vaccinated pigs were significantly lower than those in the unvaccinated pigs for the serovar 1 challenge. A significantly lower lung lesion score was also observed in the vaccinated pigs, compared with unvaccinated pigs, for serovar 2 challenge. Our work suggests that the mutant strain offers potential as a live attenuated pleuropneumonia vaccine that can provide cross-serovar protection.     

猪霍乱沙门氏菌LAMP检测方法的建立与应用

利用猪霍乱沙门氏菌lacZ基因设计特异性引物,通过优化各种反应条件,建立了检测猪霍乱沙门氏菌的环介导等温扩增（LAMP）快速检测方法。此方法特异性好,灵敏度高,将细菌DNA稀释到10-8仍可检出,是PCR方法的1000倍。本研究建立的LAMP方法操作简便、灵敏度高、特异性强,为临床检测猪霍乱沙门氏菌和预防人猪霍乱沙门氏菌病提供了技术保障。     

甘肃黄鸡早期生长发育规律的分析

为探讨甘肃黄鸡的育效果及其利用价值，对甘肃黄鸡早期生长发育规律进行了系统测定。结果表明，甘肃黄鸡体重达２．０kg的日龄平均为８７．５d（公鸡７７d，母鸡９８d)，全期饲料转化比为２．９３，成活率较高达９４．０％，甘肃黄鸡９周龄时体重接近１．５kg,有一定的市场意义，可以考虑及早上市；对甘肃黄鸡体重进行选择时，应同时注意对胫长的适当控制。     

“荧光”蚕品种雌雄荧光色素的定性及相对量分析

用高效液相色谱分析和纸上色层分析法 ,对家蚕“荧光”品种雌雄幼虫和茧层的荧光色素进行了定性和相对量分析。结果表明 :构成雌雄茧层荧光色素的种类无显著差异 ,雌雄茧荧光色不同的原因是组成茧荧光色的各种荧光色素相对量不同 ;茧层中的一种Rf值为 0 77的黄荧光色素 ,在熟蚕丝腺中没有检出 ,说明营茧过程中有新的荧光物质形成或有较大的变化 ;5龄幼虫不同发育时期 ,雌雄各荧光色素的相对量不同 ,以荧光黄色素为例 ,雄性随日龄的增加其相对量不断增加 ,而雌性则以 5龄 96h为最高 ,其后逐渐下降 ;雌性幼虫肠壁组织中的Rf值为0 19和 0 5 9的两种明黄色荧光色素 ,雄性幼虫和雌性幼虫的其它组织中没有检出 ,说明雌雄幼虫在色素代谢上也存在差异     

Incidence and effects of West Nile virus infection in vaccinated and unvaccinated horses in California

A prospective cohort study was used to estimate the incidence of West Nile virus (WNV) infection in a group of unvaccinated horses (n = 37) in California and compare the effects of natural WNV infection in these unvaccinated horses to a group of co-mingled vaccinated horses (n = 155). Horses initially were vaccinated with either inactivated whole virus (n = 87) or canarypox recombinant (n = 68) WNV vaccines during 2003 or 2004, prior to emergence of WNV in the region. Unvaccinated horses were serologically tested for antibodies to WNV by microsphere immunoassay incorporating recombinant WNV E protein (rE MIA) in December 2003, December 2004, and every two months thereafter until November 2005. Clinical neurologic disease attributable to WNV infection (West Nile disease (WND)) developed in 2 (5.4%) of 37 unvaccinated horses and in 0 of 155 vaccinated horses. One affected horse died. Twenty one (67.7%) of 31 unvaccinated horses that were seronegative to WNV in December, 2004 seroconverted to WNV before the end of the study in November, 2005. Findings from the study indicate that currently-available commercial vaccines are effective in preventing WND and their use is financially justified because clinical disease only occurred in unvaccinated horses and the mean cost of each clinical case of WND was approximately 45 times the cost of a 2-dose WNV vaccination program.     

新形势下发展蚕桑产业的思考--"敢问路在何方"系列谈之一

众所周知,我国是历史悠久的丝绸大国,丝绸是我国的瑰宝,它在出口创汇、传承文明及国与国之间的政治交往中,做出了不朽的贡献.如今我们仍沿着先人开拓的丝绸之路继续传播着古已有之、今时更浓的丝绸文化.