黑河流域中游荒漠区沙尘暴、扬沙和浮尘监测及其与气候因子的关系

[目的] 分析黑河流域中游荒漠区沙尘暴、扬沙以及浮尘频次和时长的月变化和年变化，并分析其与主要气候因子的关系，为区域沙尘天气的早期预警和荒漠区的经营和管理提供依据。[方法] 利用黑河流域红沙窝荒漠化综合防治试验站的2010—2019年的沙尘天气监测数据和气象数据进行分析。[结果] 沙尘频次和时长主要集中在春季，其次是冬季，春冬两季的频次和时长各占全年的82.3%和79.4%。10 a间沙尘暴和扬沙频次总体变化趋势逐渐减少，而浮尘频次总体变化趋势逐年增加；沙尘时长总体变化趋势逐年增加。沙尘频次月变化与土壤湿度（10 cm）和大气湿度之间呈极显著负相关（p<0.01），与风速之间呈极显著正相关（p<0.01）。扬沙年际发生频次与土壤温度（5 cm）之间呈显著负相关（p<0.05），与大气温度之间呈极显著负相关（p<0.01）。[结论] 近10 a来，黑河流域中游荒漠区的沙尘天气主要发生在春季和冬季，破坏性较大的沙尘暴和扬沙逐年减少，而浮尘逐年增加。沙尘频次的月变化主要影响因素是浅层土壤湿度、大气湿度和风速。春季的浅层土壤湿度影响了沙尘暴和扬沙年际频次变化，浅层土壤温度影响了浮尘年际频次变化；冬季的浅层土壤温湿度和降水量影响了沙尘暴的年际频次变化，浅层土壤温度和大气温度影响了扬沙的年际频次变化。     

足球场草坪运动质量影响因素的研究进展

综述了国内外足球场草坪运动质量影响因素的若干研究进展 ,并对当前我国足球场地草坪存在的问题进行了探讨     

引起笼养蛋鸡疲劳症的主要因素研究

本试验以营养因子、产蛋率、钙源、笼养生态等角度对笼养蛋鸡疲劳症进行综合研究,寻找引起笼养蛋鸡疲劳症的主要因素及减少笼养蛋鸡疲劳症的途径。     

乌鳢生长发育的生态因子及其流行病的防治

对非生物生态因子———水、光照、温度、溶氧、降水等和生物生态因子———食物、流行病和群体密度等对乌鳢生长发育的影响及流行病的防治进行了综述。     

Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. II. Post-weaning diarrhoea

This study comprised 48,931 litters in 89 sow herds. During the study (1976-82) weaning age decreased from approx. 42 days to approx. 30 days. The mean incidence of post-weaning diarrhoea was 6.0% of litters weaned, with little variation by year but with considerable variation among herds. Within the individual herd increased incidence occurred over limited periods, probably associated with specific infections. Litters with diarrhoea during the suckling period had increased risk of post-weaning diarrhoea. The incidence of post-weaning diarrhoea increased with litter size at weaning. Thus, a litter of 11-12 piglets at weaning had 1.2 times higher risk than litters with 8-10 piglets. In contrast to pre-weaning diarrhoea, there was no association between parity of the sow and diarrhoea in the litter after weaning. Litters weaned below 2 weeks of age had a 2-fold risk of developing diarrhoea after weaning and a 2.4-fold higher mortality rate than did litters weaned at 6-7 weeks. Similarly, litters weaned at an individual piglet weight below 3 kg bodyweight had a 3-fold higher risk of developing diarrhoea after weaning and a 5-fold higher mortality rate than did pigs from litters weaned at a bodyweight of 7-8 kg. The incidence of post-weaning diarrhoea decreased with increasing herd size. Piglets from litters with post-weaning diarrhoea had reduced weight gains after weaning and were 2.3 days older at 25 kg bodyweight than piglets from non-diarrhoeic litters. Likewise, diarrhoea after weaning was associated with an increased incidence of diseases of the skin and respiratory tract. Thus the risk of contracting respiratory disease was 4 times greater in diarrhoeic litters.     

胆盐和游离脂肪酸影响离体小肠细胞类胡萝卜素吸收的研究

用黄鸡小肠细胞进行了 β-胡萝卜素和黄体素的体外吸收试验 ,研究类胡萝卜素浓度、胆盐和游离脂肪酸对这两种类胡萝卜素吸收的影响。结果发现 :β-胡萝卜素和黄体素的吸收均呈浓度依赖性 ;牛磺胆酸钠极显著促进黄鸡离体小肠细胞类胡萝卜素的吸收(P<0.01) ,其促进 β-胡萝卜素和黄体素吸收的最佳浓度分别为3mM和10mM ;游离脂肪酸极显著促进了类胡萝卜素的吸收(P<0.01) ,其中油酸对类胡萝卜素的促吸收作用大于硬脂酸 ,促进 β-胡萝卜素和黄体素吸收的最佳油酸/硬脂酸比率分别为100 :0和3 :1。牛磺胆酸钠和游离脂肪酸影响 β-胡萝卜素吸收的动态变化模式与它们对黄体素的显著不同     

影响老瓜头泌蜜量主导因素的研究

老瓜头自然分布于沙漠地带。在老瓜头开花期,天气变化无常。我们研究了对老瓜头泌蜜量起关键影响作用的气象因子。根据当地气候的变化规律进行预测预报,指导养蜂者正确选择场地,以夺取老瓜头蜜高产。     

大肠杆菌毒力因子研究概况

致病性大肠杆菌的毒力因子主要有黏附素、毒素、外膜蛋白 ( OMP)及铁转运系统等。在大肠杆菌侵袭宿主组织并引起其发病的过程中 ,这些毒力因子相互协调、发挥作用。文章对毒力因子的致病作用、致病机理、免疫原性及其在疾病防制中的应用几个方面的研究概况作了综述 ,为防制大肠杆菌病、研制新型高效的大肠杆菌疫苗提供了理论依据。另外 ,文章还介绍了近年来已相继研制成功的全菌体疫苗、纯化菌毛疫苗、单价或多价基因工程菌毛疫苗以及重组肠毒素双价基因工程苗、OMP亚单位疫苗等。展现了新型疫苗的研制 ,给防制大肠杆菌病带来了新的前景以及大肠杆菌作为工程菌的应用对畜禽其他疾病防制的推动作用     

Effect of the Pietrain breed used as terminal boar on Post-weaning Multisystemic Wasting Syndrome (PMWS) in the offspring in four PMWS-affected farms

The aim of this study was to determine the potential risk factors for PMWS at the individual pig level and assess the effect of the Pietrain paternal genetic background of the animals in a cohort study. The survey was set up in four PMWS-affected farms with 2 repetitions (batches) per farm. A representative sample of 60 pigs per batch, stratified according to the paternal genetic background (Pietrain: yes vs. no), was randomly selected after farrowing. The representative cohort was divided into 8 batches and the pigs were individually monitored from birth to slaughter. Survival analysis was used to determine the factors related to the time to PMWS. The litter-cluster effect was taken into account using the marginal Cox model (robust estimation of the covariance matrix) and the gamma shared frailty model which were compared.No protective effect of the Pietrain breed on the time to PMWS and the proportion of affected pigs in the offspring was found in this study. Piglets showing low circovirus type 2 (PCV2) titres at 7 weeks-old with no subsequent seroconversion and piglets from PCV2 negative sows were most likely to be affected by PMWS (HR=7.0 and 2.8, respectively). Active infection of the pregnant dams with parvovirus was related to an increased risk of PMWS in the offspring (HR=2.3). Neck injuries due to poorly performed injections in the dams were associated with an increased risk of PMWS with the marginal model (HR=2.1). Oxytocin injection (dams) during farrowing was protective against PMWS in the offspring (HR=0.6).