在不同的光学调制度水平下测定的对比敏感度函数

前文中,我们根据小尺寸矩形孔的 MTF(T_□)在高频部分的下降比对比敏感度函数(Tcs)下降快得多的事实,揭示了随空间频率(SF)的增加,网膜-大脑系统的 MTF(Trb)表现愈趋明显的补偿作用。     

中国科学院植物生理研究所学术委员会召开生长素工作座谈会

今年(1957)2月6日至8日,我們在上海舉行了植物生長素工作座談會,這個會議由中國科学院植物生理所學術委員會根據國家科學技術规劃中的第2717、2719、4510等項任務,邀請了化學家、農學家、植物生理學家十餘人座談和討論植物生長素及各種植物生長刺激物質的應用、理論和今後研究方向等問題。 會議第一天,首先由植物生理所羅宗洛所長作簡短的講話,說明這次會議的意義;接着由楊石先、婁成后、李曙轩、湯玉璋等四位教授在會上分别作“植物刺激劑的化學研究”、“化學除     

Excision of precancerous lesions of the lip

A method of surgical treatment of precancerous lesions of the lip, by excision of the vermilion border and the advancement of the inner mucosa of the lip to cover the defect, satisfactorily removes the entire lesion and restores normal tissue to the lip surface.     

High Fitness of Heterokaryotypic Individuals Segregating Naturally within a Long-Standing Laboratory Population of Drosophila silvestris

Natural populations of Drosophila silvestris are polymorphic for inversions in one or more of four of the five major chromosome arms; laboratory stocks tend to retain this heterozygosity. A laboratory stock, U28T2, was started from a single naturally inseminated wild female caught at Kilauea Forest Reserve, Hawaii, in January 1977. Polytene analysis in 1980 showed the presence of three natural inversions in chromosome 4: k ² is distal, t is central and l² is proximal. The inversions are short but only short uncovered euchromatic sections exist at the distal and proximal ends. Periodic examinations through 1986 showed all three inversions to be persistent at moderately high frequencies. In 1984, a series of tests of mating performance of caged, mature males, taken at random as they eclosed from the stock, were followed by cytological testcrosses to females from a homokaryotypic stock. Only three of the eight possible haplotypes, k²/t/+ (A), +/+/l² ( a) and +/+/+ (a') were present. Tests of crossing over show none in males; in females, there is about 1% in each of the two regions between the inversions. Only one such apparent crossover haplotype was found among 1084 examined in samples from this stock. Thus, chromosome arrangements A, a and a' virtually behave as wholechromosome alleles in both sexes. Of 146 males marked and tested in cages, 61 produced progeny; the others failed to reproduce. Of 58 males and 80 females producing progeny and analyzed cytologically, there were, respectively, 49 and 59 heterokaryotypes. On the basis of frequencies calculated for fertilized eggs, 33.6 males and 46.3 females are expected. The facts suggest that individual males with the Aa karyotype are particularly successful in production of offspring. Adult females show an excess of Aa' as well as Aa. Such high fitness of heterokaryotypes in the effective breeding adults could be a major factor in the maintenance of stable chromosomal polymorphisms both in laboratory stocks and in nature. Although some of this heterosis is clearly ascribable to differential survival, the facts suggest that there is a substantial opportunity, indeed a likelihood, for a contribution from differential mating among surviving adults.     

长滩果引种驯化研究

长滩果系罗汉果最佳品种。原产区分布于永福和临桂县交界400—600米山区,但不适应于低丘陵和平原地区,因而不能在低丘陵和平原地区推广。为了解决这个问题。采用了(1)选择湿润和半阴的生长环境;(2)采用适应性强的砧木;(3)促成栽培;(4)加强秋旱期的科学管理等措施并取得成功,试验结果表明长滩果产量和品质达到或略超过原产区水平。     

传入C纤维的兴奋在中电针“足三里”激活中缝大核中的作用

The purpose of the present work is to study whether the analgesia of "Zusanli" EA was mainly produced by its noxious effect. The antidromic C waves on N. peroneus communis innervating the area of "Zusanli" point were recorded. When "Zusanli" point was stimulated by trains of stimuli, the amplitude of the antidromic C wave was obviously decreased due to collision with the orthodromic stimulation. It was suggested that EA of "Zusanli" could excite some C fibers. It was observed that when the stimulation intensity reached the threshold of C fiber, the NRM neurons were obviously activated, and when it reached or exceeded the intensity for producing the maximal C wave, the NRM neurons were highly activated. Therefore, EA analgesia is probably produced mainly by its noxious stimulus component, especially carried by C fibers, via a negative feedback mechanism in modulating pain.     

原生质体来源的大白菜悬浮细胞系的超低温保存

原生质体来源的大白菜 Brasstca campessris var.pekinsis 悬浮细胞系在二甲亚砜的保护下,能在液氮中(-196℃)长期冻存。加入山梨醇能增强保护作用;而加入甘露糖则降低保护作用。培养基对冻存也有明显的影响。在液氮中存放的时间长短对细胞存活率没有多大影响。冻后相对活性最高可达75.4％,恢复生长快,化冻后重新悬浮培养6天,生长量可达300-500％。遮光比不遮光对恢复更有利。冻存后恢复生长的悬浮细胞,能与未经冰冻的对照一样进行原生质体分离和培养。