Atrioventricular valvular angiectasis in Sprague-Dawley rats

Subendothelial heart valve angiectasis has been reported in cows, dogs, pigs, rats, mice, and in human fetuses and newborns. We observed a high incidence (62 in 208 animals examined) of spontaneous angiectasis on the atrioventricular (AV) valves in 10- to 40-week-old Sprague-Dawley rats. The angiectasis was observed predominately on the septal cusp of the right AV valve and located near the AV ostium in 57 of 62 animals. Of the remaining 5 valvular angiectases, 2 were present on the parietal cusp of the right AV valve and 3 were on the left AV valve. The angiectases were single or multiple, ranging from 40 to 300 microm in diameter and were characterized by light microscopy as blood-filled dilatations lined by endothelium. Spontaneously occurring abnormalities in normal laboratory animals, such as the spontaneous valvular angiectasis reported here, need to be differentiated from drug-related lesions.     

Hermaphroditism in a Sprague-Dawley rat

A spontaneous case of unilateral true hermaphroditism was observed during the routine necropsy of a 9-week-old presumed female Sprague-Dawley rat on a repeat-dose toxicity study. There were no drug-related effects observed. True hermaphroditism is rare in rats, and despite the large numbers of rats examined annually, few cases are reported in the literature.     

The use of genetic resources in crop improvement: Lessons from China

The use of crop genetic resources in improvement programmes should be the ultimate objective of all undertakings in the field of germplasm resources. The present situation and future direction of the use of crop germplasm in China was assessed from responses to a questionnaire distributed to 165 plant breeders and curators nationwide. The general opinions for the limiting factors of germplasm utilization were also evaluated. Responses from the questionnaire indicated that the use of germplasm in breeding programmes is much more important than the direct use of germplasm in crop production as cultivars released. Among different types of crop genetic resources, released varieties and breeding lines contribute more to crop breeding. Wild relatives and genetic stocks, however, are expected to play a greater role in the future. Landraces will remain important in improvement. Limited useful germplasm available to breeders is the basic reason for the insufficient use of germplasm in crop breeding at present. The complex reasons which affect the availability of useful germplasm involve the research level, links between breeder and curator and others. To counter these, we propose some suggestions and measures which can be implemented in the near future.     

不同夜间温度对小麦旗叶光合作用和单株产量的影响

本文用不同夜间温度连续处理抽穗开花后的小麦植株,对旗叶的光合作用和单株产量进行了比较研究。结果表明夜间低温能明显延长叶片叶绿素含量缓降期和光合速率高值持续期,从而增加叶片的叶源量,提高产量。经计算缓降期延长一天,可使单株产量和千粒重分别提高2.0-2.5%和1.5-2.0%。夜间高温处理植株效果相反。试验进一步研究     

白跗平腹小蜂林间动态研究*

白跗平腹小蜂在浙江于4月中下旬自然羽化,10月上旬在第3代马尾松毛虫卵中,n月在柳杉毛虫卵中, 以老熟幼虫越冬, 翌年4月中下旬开始羽化活动。在自然温度下, 用柞蚕剖腹卵繁殖, 年发生6~7世代。在林间的年周期活动中, 其种群数量分别在5-6月和9-10月出现两次高峰。这和马尾松毛虫、柳杉毛虫、水青蛾、大背天峨和油茶枯叶峨等主要森林害虫的卵期吻合。该蜂对它们的抑制力分别是16.55%~22.90%, 23.45%, 2.63%~5.49%,1.97%和3.00%~7.00%。该蜂在林间的水平扩散距离达32m以上。     

辅助热源式太阳房的热工计算分析

论述了主动与被动太阳能加热设备结合辅助加热器获得高效能太阳房的工作原理与热工计算方法,并结合所设计太阳能加热系统进行了热工计算与分析．     

纸层析分离转氨作用产物方法的改进

本文介绍作者研制的一种用于纸层析分离转氨作用产物──氨基酸的展层剂,它含有乙醇、水和尿素（80：20：0．5）,与传统的展层剂苯酚和水相比,它具有价格便宜（节省经费217％）、安全无毒、操作方便等优点,是一种理想的展层剂。     

落叶松红瘿球蚜生物学特性及防治研究初报

落叶松红瘿球蚜是危害云杉、青海云杉枝梢嫩芽的一种重要害虫。在甘肃甘南林区１年发生２代,未发现有性世代和第２寄主,为不完全生活史型。该越冬蚜虫从翌年５月上旬开始活动,中、下旬产卵。６月上旬越冬成蚜和第１代若蚜取食刺激形成虫瘿,瘿蚜在瘿室内３龄,７月中、下旬至８月上旬虫瘿开裂羽化为具翅瘿蚜活动产卵,８月上、中旬卵孵化,１龄若蚜（越冬蚜）于９月中旬至１０月初在枝梢顶端叶基或芽基越冬。在第１代１龄若蚜越冬前,春季越冬蚜产卵前和瘿蚜羽化产卵前用５０％抗蚜威可湿性粉剂２０００～２５００倍液防治,防治效果达９０％以上。     

熟玉米淀粉的消化率及其对肉牛氮沉积和血糖浓度的影响

采用4×4拉丁方设计,4头杂交肉牛按1.2倍维持需要(1.2M)饲养水平供给羊草,在此基础上由真胃灌注的熟玉米淀粉以研究其对肉牛氮沉积的影响,结果如下:真胃灌注熟玉米淀粉量300,600,900g·d~(-1)与对照组(0g·d~(-1))相比,沉积氮(RN)均有极显著的提高(P<0.01),沉积氮/可消化氮(DN)亦有显著提高(P<0.05);真胃灌注熟玉米淀粉量300,600,和900g·d~(-1)时,瘤胃后段消化道的熟玉米淀粉的消化率分别为71.36%,80.27%和64.71%;真胃灌注熟玉米淀粉后,血糖浓度提高,血液胰岛素和尿素氮浓度下降。     

雪莲的生殖生态学研究 Ⅰ.生境、植物学及物候学特性

本研究对生长在新疆天山１号冰川附近高山带的雪莲,从生境土壤的理化性质、气象因子等方面进行了统计和分析,并对其植物学及物候学特性进行了较详细的观察和分析,结果表明：雪莲为多年生一次开花结实的草本植物,生育年龄为５～６ａ,其生长的土壤环境极为严酷,植株营养器官及繁殖器官的形态特征、生长发育及繁殖的节律是与其特殊的气候条件相适应的。