敌百虫在乌鳢体内和水环境中的代谢动力学及残留研究

[目的]明确敌百虫在水产养殖中的安全性。[方法]全池泼洒0.5 mg/L敌百虫,采用气相色谱法测定敌百虫在乌鳢体内的代谢动力学和残留消除规律。[结果]乌鳢组织和水样中敌百虫的最低检测限为0.02μg/m L。随着时间的延长,敌百虫在乌鳢血液中的浓度逐渐升高,120 h达最高,为0.072 mg/kg,至360 h时未检出。肌肉中12 h内未检出,24 h浓度为0.023 mg/kg,120 h检出最大浓度0.051 mg/kg,至288 h未检出。肝脏8 h未检出,12 h检出浓度为0.026 mg/kg。使用敌百虫后,乌鳢体内的药物残留量均低于我国的兽药最高残留限量要求,但在养殖水体中的残留时间较长,降解半衰期为35.19 h。[结论]为确保敌百虫使用后对水生态环境及食品安全,建议敌百虫使用后的休药期为150℃·d。     

小麦赤霉病防治研究进展

综述了小麦赤霉病防治研究的国内外发展概况、发展趋势,阐明了小麦赤霉病的发生特点、状况以及综合治理现状,分析在小麦赤霉病防治中存在的问题,并提出了治理策略,明确了针对小麦赤霉病防治的具体措施及未来展望。     

桥头跳车的成因分析与防治处理

简单分析了公路桥头跳车的各种原因,对解决桥头跳车问题的防治技术进行了总结。     

Genetic diversity of Australian Fusarium graminearum and F. pseudograminearum

Genotypic diversity in Fusarium pseudograminearum and F. graminearum from Australia and the relationship between diversity and pathogen aggressiveness for head blight and/or crown rot of wheat were examined. Amplified fragment length polymorphism (AFLP) analysis revealed a high level of genotypic diversity within each species. Sixty-three of the 149 AFLP loci were significantly different between the two species and 70 of 72 F. pseudograminearum and 56 of 59 F. graminearum isolates had distinct haplotypes. When head blight and crown rot severity data from a recently published work on isolates representing the entire range of aggressiveness were used, only the genotypic diversity of F. pseudograminearum was significantly associated with its aggressiveness for the two diseases. Cluster analyses clearly demonstrated the polyphyletic structures that exist in both pathogen populations. The spatial diversity within F. graminearum was high within a single field, while frequent gene flow ( N _m ∼ 14) and a low fixation index ( G _st = 0·03) were recorded among F. pseudograminearum isolates from the adjacent states of New South Wales and Queensland. The differences in population structure between the heterothallic F. pseudograminearum (teleomorph G. coronicola ) and the homothallic F. graminearum (teleomorph G. zeae ) were not as pronounced as expected given their contrasting mating systems. Neither species was panmictic or strictly clonal. This points to sexual recombination in F. pseudograminearum , suggesting that ascospores of G. coronicola may also play a role in its biology and epidemiology.     

商洛市核桃低产幼树高接换优技术

通过对商洛市核桃低产实生幼树采取薄膜包扎、报纸遮荫插皮舌接或装土保湿插皮舌接技术方法的示范和推广,总结出了适合商洛市核桃低产幼树高接换优技术措施,并在生产中广泛推广应用。     

万家沟水库拱坝坝顶泄水溢流坝的设计及施工

我国是修建中低拱坝最多的国家，自本世纪７０年代以来大部分拱坝采用了坝顶溢流的泄洪方式。本文以万家沟水库拱坝溢流坝的设计为例，阐述了这种坝型设计及施工的一些特殊问题及解决方法。混凝土溢流坝的施工，大中型工程多采用滑模，速度快、省投资，但中小型工程多没有滑模设备，万家沟工地自制了简易滑模，高质量高效率地进行了溢流坝的施工，为同类工程提供了有益的借鉴。     

8×4视频切换器控制系统

用ＭＣＳ－５１单片机控制８×４视频切换器，其中４路为视频输出，８路为视频输入，对８路云台和８路镜头进行控制，主控制器可以是一台计算机，专用控制盒或其它设备，本对其硬件实现和软件中使用的命令介绍一种应用方法。     

鸭肿头出血症病毒强毒的致病性及感染组织细胞的超微病理变化

将鸭肿头出血症病毒（DSHDV）强毒株以不同途径接种10日龄鸭胚，研究了病毒在鸭胚中的繁殖规律，并用透射电镜观察了感染鸭胚各组织器官的超微结构变化，同时用DSHDV人工感染不同日龄雏鸭，比较了不同感染途径对雏鸭的致病性和对不同日龄雏鸭的致病性。结果显示，尿囊腔和卵黄囊2种途径均能使病毒在鸭胚上繁殖并传代，对鸭胚的半数致死量分别为10^-7.24／0．2mL和10^-6.4／0．2mL。病毒感染鸭胚后，电镜下可观察到肝和尿囊膜中的病毒粒子，病毒粒子呈球形或椭圆形，大小为60～80nm，无囊膜；病毒在细胞浆内复制，可形成特征性包涵体；病毒侵害的主要靶器官为尿囊膜与肝，细胞器的变化主要表现为粗面内质网扩张以及线粒体肿胀和嵴断裂、消失。病毒经肌肉注射、口服和滴鼻均能使28日龄鸭感染发病，致死率分别为86％、89％和97％。研究表明，DSHDV能很好地在鸭胚上生长并致鸭胚各组织器官超微结构发生变化，不同感染途径均能使雏鸭感染发病且致病性强。     

RADIOGRAPHY OF THE CANINE HEAD

Through the use of a purebred dog skull collection, specific positioning recommendations were established for radiography for the three skull types. It is suggested that the central ray of the beam be maintained at the following mean angles relative to the hard palate for the rostrodorsal-to-caudoventral oblique projection of the foramen magnum: dolicocephalic, 30° mesaticephalic, 20° and brachycephalic, 10°. It is recommended that the head be axially rotated as follows to radiographically separate the roots of the superior canine teeth: dolicocephalic, 48° mesaticephalic, 43° and brachycephalic, 35°. If only the cheek teeth require evaluation, the head should be rotated as follows: dolicocephalic, 37° mesaticephalic, 34° and brachycephalic, 25°. For evaluation of the inferior cheek teeth, it is recommended that the head be rotated as follows: dolicocephalic, 46° mesaticephalic, 44° and brachycephalic, 28°. It is recommended that radiographs of the temporo-mandibular joint be made with the skull axially rotated 10° and longitudinally obliqued as follows: dolicocephalic, 10° mesaticephalic, 14° and brachycephalic, 27°. Suggestions for open-mouth projections for evaluation of the tympanic bullae are that the central ray maintain the following angles relative to the hard palate: dolicocephalic, 4° mesaticephalic, 9° and brachycephalic, 21°. It is recommended that a caudoventral-rostrodorsal oblique projection of the nasal cavity made at 30° to the hard palate replace the open-mouth ventrodorsal in brachycephalic breeds.     

对公路桥头跳车原因与防治浅见

分析了桥头跳车的危害及原因,论述了软土地基加固处理、桥头搭板刚柔过渡、台背填料的选择等综合治理桥头跳车的方法和经验。