APPLIED PHYSICS: Smaller, Faster Midinfrared Lasers

Semiconductor lasers are small, efficient devices that are used widely as optical sources in telecommunication systems and CD-ROM and DVD optical memory drives. In his Perspective, Faist highlights the work by Paiella et al., who expand the range of operation of these devices substantially by demonstrating midinfrared lasers that emit picosecond pulses. Faist particularly stresses the innovative technique used by the authors, which may also allow new frequencies, for example in the terahertz frequency range, to be generated.     

小绿叶蝉的大发生成因及防治

本文介绍了解小绿叶蝉的生活习性、为害症状,剖析该虫大发生成因,从农业生产角度,提出相应的防治方法。     

小范围杨树黄斑星天牛综合防治技术

区域性带状、团状、块状发生的杨树黄斑星天牛疫点,用6项措施进行综合防治,取得了明显的效果,被害株率和虫口密度较防治对照区明显下降。防治区与对照区差异t检验表明达到极显著水平。结果证明综合防治措施是预防和除治杨树黄斑星天牛有效的途径。     

槐小卷蛾研究初报(简报)

北京地区一种为害槐和龙爪槐的鳞翅目害虫,在50年代发生为害较重,后来因防治其他害虫等原因把它兼治下去了,但近年来又有逐年发生、为害加重的趋势。它蛀食槐和龙爪槐羽状复叶的叶柄和小枝,使被害叶柄下垂、枯死和脱落,受害严重的寄主在秋季出现秃枝、秃顶的现象。严重影响槐和龙爪槐的生长发育和观赏价值,重新引起人们对它的重视。     

几种缩小密集烤房层间温差的材料应用效果研究

[目的]探讨几种缩小密集烤房层间温差的材料的应用效果.[方法]为解决密集烤房烘烤过程中上下棚烟叶变黄干燥不均匀、局部烟叶易挂灰或烤青等问题,采用化纤毛毯、棉纱布、无纺布等材料置于烤房顶部,以缩小上下棚间的温度差,观察上棚下棚温湿度变化情况,及对烤后烟叶质量的影响.[结果]试验表明,在密集烤房使用化纤毛毯或棉纱布一类吸水物质后,能显著提高上棚湿球温度水平,平均提高0.24 ～0.31℃(最高点达0.70℃),且化纤毛毯处理能明显缩小同层干湿球温度差,相对对照平均缩小0.41℃;化纤毛毯处理、棉纱布处理烤后烟叶外观质量、经济性状、单位能耗相对对照也有明显改善.[结论]研究可为解决密集烤房烘烤中上下棚烟叶变黄干燥不均匀、局部烟叶易挂灰或烤青等问题提供参考.     

不同药剂防治茶树茶小绿叶蝉效果研究

不同药剂防治茶树茶小绿叶蝉效果研究表明,25%噻嗪酮可湿性粉剂、20%啶虫脒可溶性粉剂、10%联苯菊酯水乳剂、10%高效氯氟氰菊酯乳油对茶小绿叶蝉均具有较高的防效,25%噻嗪酮可湿性粉剂和20%啶虫脒可溶性粉剂不但防效高、持效期长,而且对捕食性天敌杀伤较小,可作为防治茶树茶小绿叶蝉的药剂推广。     

不同药剂防治水稻灰飞虱及条纹叶梧病的研究

[目的]比较市场上可同时控制灰飞虱和水稻条纹叶枯病的不同药剂的防效,并检验其对水稻的安全性,为选用适宜的药剂提供参考。[方法]以清水为对照,进行了25%吡蚜酮.噻虫嗪悬浮剂及其与毒氟磷混配剂、吡蚜酮单剂等5种药剂对水稻灰飞虱及水稻条纹叶枯病的防效试验。[结果]吡蚜酮.噻虫嗪及其与毒氟磷混配剂、吡蚜酮单剂对秧田灰飞虱成虫均具有较好的控制效果,在灰飞虱大发生年份,秧田第4次药后7 d防效均在75.00%以上;25%吡蚜酮.噻虫嗪悬浮剂及其与毒氟磷混配剂、吡蚜酮单剂对水稻条纹叶枯病防效也较好,大多在70.00%以上。[结论]吡蚜酮.噻虫嗪及其与毒氟磷混配剂、吡蚜酮单剂对水稻灰飞虱及条纹叶枯病均具有较好的防效,可在水稻生产中推广应用。     

麦田灰飞虱的发生及其传播的条纹叶枯病对小麦的危害

灰飞虱在江苏淮河流域 1年发生 5～ 6代 ,以 3、4龄若虫越冬为主 ,稻田套种的小麦是主要越冬源。翌年 3月到 4月初成虫羽化 ,长翅型个体比例极低 ,成虫在原发生地生活 10～ 15d后 ,大范围扩散 ,主要选择在麦田产卵繁殖。 1代若虫于 4月底到 5月初孵化 ,随气温上升和植株衰老逐渐到麦穗上栖息取食并完成发育 ,成为水稻条纹叶枯病的传播者 ;越冬代灰飞虱在麦田传播条纹叶枯病并引起小麦严重发病 ;1代灰飞虱发生量大 ,直接取食致害 ,但不能引发小麦条纹叶枯病     

LSD: no teratogenic action in rats, mice, and hamsters

Lysergic acid diethylamide tartrate was given to 98 pregnant rats, 67 mice, and 22 hamsters as a single dose of 5 to 500 micrograms per kilogram of body weight per day either at the beginning of gestation or during the period of organogenesis. Examination of the 1003 rat fetuses, 521 mouse fetuses, and 189 hamster fetuses obtained failed to prove any abortifacient, teratogenic, or growth-depressing effects.     

灰飞虱与水稻条纹叶枯病大暴发的因果关系及控制途径

分析了江苏省建湖县灰飞虱与水稻条纹叶枯病大暴发因果关系的特点、原因 ;并提出了控制途径。     

Radiation effects in free-ranging pocket mice, Perognathus parvus, during the breeding season

Captive and free-ranging Great Basin pocket mice, Perognathus parvus, were exposed to ionizing radiation during the breeding season, April-June, in 1971. The values for the median lethal dose (LD(50)) at 30 days plus or minus the standard deviation were 880 +/- 14 rads and 780 +/- 27 rads, respectively, and the slopes of the survivorship curves were significantly different. These differences suggested that there was a synergism between radiation-induced and environmental sources of mortality, since the field data were corrected for natural mortality (5 percent) in the controls.     

Brain lesions, obesity, and other disturbances in mice treated with monosodium glutamate

In newborn mice subcutaneous injectionis of monosodium glutamate induced acute neuronal necrosis in several regions of developing brain including the hypothanamus. As adults, treated animals showed stunted skeletal development, marked obesity, and female sterility. Pathological changes were also found in several organs associated with endocrine function. Studies of food consumption failed to demonstrate hyperphagia to explain the obesity. It is postulated that the aduls syndrome represents a multifacted nueroendocrine disturbance arising from the disruption of developing nueral centers concered in the mediation of endocrine function.     

Steroids and serum complement in mice: influence of hydrocortisone, diethylstilbestrol, and testosterone

Hydrocortisone depresses hemnolytic complement in male and female mice. Testosterone causes increase of serum complement in female mice, and diethylstilbestrol causes decrease of serum complement in male mice, in each instance to activities approximating those found normally in the opposite sex. Male and female sex hormones have no effect, in the doses used, on the serum complement of male and female mice respectively.