北京春季沙尘天气特征和预报

根据北京地区资料分析了沙尘的年代变化、月变化,春季是沙尘天气的高发期并以浮尘和扬沙为主。造成沙尘天气的冷空气主要有三条路径,它与蒙古气旋、冷锋、高空急流等大尺度天气系统紧密相连。     

专家系统在植保上的应用

专家系统在植保上主要应用于病虫害诊断、预测预报、决策管理等领域。植保专家的特点是应用范围广、实用性增强、新技术和新方法不断应用、有向综合性系统发展的趋势。文中还对植保专家系统存在的问题和发展对策进行了讨论。     

云南省小麦条锈病流行体系的研究现状

对云南省小麦条锈病的发生危害、流行特点、条锈菌越夏规律、品种及小种变异、环境因素等流行体系作 了较为详细的叙述,并针对各个环节提出综合防治策略。     

Advances in studying the differentiation into neurons of mesenchymal stem cells and their application

Mesenchymal stem cells (MSCs) are a population of multipotent cells that can proliferate and differentiate into marrow and non-marrow cell types, such as adipocytes, chondrocytes, myocytes, and so on. In recent years, many researchers have studied whether MSCs are capable of differentiation into neurons in vivo and ex vivo. The result that MSCs-derived neurons express NSE and NF, but don't express GFAP suggests MSCs can differentiate into neurons, some researchers have achieved success in promoting functional recovery in Pakinsons and transactional spinal cord injury rat models by use of MSCs-derived neurons. Therefore, MSCs-derived neurons will play an important role in the therapy for a variety of diseases of the nervous system.     

猪瘟病毒E2(gp55)基因在昆虫细胞中的表达

将除去3'端跨膜区的猪瘟病毒E2基因亚克隆到杆状病毒转移载体pFastBacHTb,获得重组质粒pFBHT-E2,转化进含穿梭载体Bacmid的感受态细胞DH10Bac,发生转座作用,经抗性及蓝白斑筛选得到含E2基因的重组载体质粒rBacmid-E2,以脂质体介导的方法将此重组载体质粒转染sf9昆虫细胞,获得重组病毒,命名为rvBac-E2.经SDS-PAGE和Western-blot及ELISA等方法检测,结果表明,此E2基因在昆虫细胞中正确表达,表达的蛋白能与猪瘟阳性血清发生特异性反应.     

Magnetic resonance imaging of a brain abscess in a 10-month-old filly

The purpose of this paper was to correlate the magnetic resonance imaging (MRI) characteristics of a mature brain abscess in a horse with histopathologic alterations of brain tissue. Eight months after the onset of clinical signs, MRI of the brain of a 10-month-old filly was performed. A large space-occupying lesion in the right cerebral hemisphere was identified. This space-occupying lesion was delineated by a thick and well-defined capsule that was isointense to brain parenchyma on the T1-weighted images and with a markedly hypointense on the T2-weighted images. The identification of such a capsule is highly diagnostic of a mature brain abscess. The lesion seen on MR images was confirmed at necropsy where a large abscess of the right hemisphere was observed. Streptococcus zooepidemicus and Pseudomonas aeruginosa were isolated from the abscess. Based on histopathologic examination, the signal characteristics of the capsule on T1-weighted and T2-weighted images were found to be due to the presence of numerous hemosiderin-laden macrophages. These results are in agreement with previous studies on human patients. This report confirms the value of MRI in the diagnosis of equine brain diseases.     

植物化感作用影响因素的再认识

土壤养分、酶、微生物、本底特性,根茬还田、水分、植物根系、种植体系和种植模式与化感作用的互作关系,表明这些因子可通过对土壤养分有效性、微生物种群结构、土壤酶活性和化感物质浓度的影响而对化感作用产生直接或间接影响,这些可为通过化感作用途径构建高效农田生态系统提供新的思路.     

匍匐翦股颖草坪根系对城市生活污水的净化效应

针对匍匐翦股颖草坪根系对生活污水的净化效应进行了初步的探索,结果表明,城市生活污水能显著促进匍匐翦股颖地上部分叶片的生长,其叶片生长量随着其处理的进程而逐渐增加,至第6周时叶片生长量比净水灌溉的对照增加了75.6%;根系生长在污水灌溉与净水灌溉之间未显示出明显的差异;匍匐翦股颖草坪根系对生活污水中总氮(TN)、总磷(TP)、化学耗氧量(CODCr)的去除率分别达到了71.0%、53.1%、82.8%,而无草坪的裸土对TN、TP、CODCr的去除率只有24.6%、13.0%、44.2%.结果显示了匍匐翦股颖草坪根系对生活污水有着较好的净化效果,有望在城市生活污水处理中应用.     

春季休牧对草原和家畜生产力的影响

从4月上旬到6月下旬,在内蒙古锡林郭勒典型草原,进行春季休牧试验,对休牧和非休牧的草原进行生产力监测.结果表明:春季休牧可以有效地保护草原生态环境,经过两个月休牧后,草原植被状况明显改善;休牧期间采用低投入维持性饲养,可以显著降低饲养成本.并对休牧措施的生态效益、生产实践可行性和经济合理性进行综合讨论和评价.     

优质肉鸡繁育体系的效益评估

近十多年来，我国优质肉鸡的生产方兴未艾，许多育种公司和科研院所不断推出新品系。为充分发挥新品系的遗传潜力，探求优质肉鸡最佳的繁育生产模式具有重要意义。由于不同的品系及其杂种后代在不同的性状上各有优缺点，很难用生产性能进行直接比较，而适合用育种规划的方法通过经济学指标进行评价。系统分析通过把生产系统抽象概念化并用数学手段模型化的方法，