改革求生存 创新谋发展——浅析地市级农业科学院(所)发展之路

地市级农业科学院(所)近年来,进行了一系列的科技体制改革,文章在论述以往改革的做法和成效的基础上,找出了改革中存在的几个影响发展的瓶颈问题,并进一步提出解决问题的对策。     

Transformation by v-sis occurs by an internal autoactivation mechanism

Transformation by the v-sis oncogene appears to require an interaction of its protein product, p28v-sis, with the receptor for the platelet-derived growth factor (PDGF). However, this interaction may not occur at the cell surface as predicted by the autocrine hypothesis because phenotypic transformation was not reversed by incubation of SSV-NRK cells with antisera to PDGF and because morphological transformation did not occur when nontransformed NRK cells were cultured continuously with p28v-sis. A mutant of the wild-type v-sis gene was constructed that encodes a v-sis protein targeted for retention within the endoplasmic reticulum and Golgi. NRK cells expressing the mutant v-sis gene did not secrete any detectable v-sis protein but were as fully transformed as wild-type v-sis transfectants. The results support a mechanism of transformation by v-sis in which internal activation of the PDGF receptor occurs before expression of either p28v-sis or the PDGF receptor at the cell surface.     

Hemagglutination by fava bean extract inhibited by simple sugars

Hemagglutination by extract of fava bean was inhibited by 5-percent d-glucose, d-fructose, or maltose, but not by 5-percent d-galactose or lactose. Failure to inhibit seems to reflect the presence of a hydroxyl group at the carbon No. 4 position. Hemagglutination was enhanced by dextran of high molecular weight, but not by dextran of low molecular weight. The finding supports the hypothesis that large molecular size explains the enhancement by gum acacia of hemagglutination by fava bean.     

Interferon: production by chick erythrocytes activated by cell fusion

In the presence of Sendai virus inactivated with ultraviolet light, nucleated chick erythrocytes can be fused with several types of human cells to form heterokaryons. Although chick erythrocytes alone cannot be stimulated by Sendai virus to produce interferon, fusion with a human cell (AH-1) which itself may produce human interferon results in heterokaryons in which the erythrocyte genome is activated and chick interferon is produced. When nucleated chick erythrocytes are fused with another type of human cell (HeLa clone S-3) which does not produce human interferon when stimulated, no chick interferon is detectable, despite morphologic changes suggestive of activation of the erythrocyte nuclei.     

依法治校与以德治校的思考

依法治校与以德治校是学校管理科学化、规范化的必须和标志。文章以实际工作中存在的一些问题为背景，就如何坚持依法治校与以德治校提出处理好若干关系的建议，指出依法治校是学校管理的保障和前提，以德治校是学校发展的灵魂和动力。     

Language discrimination by human newborns and by cotton-top tamarin monkeys

Humans, but no other animal, make meaningful use of spoken language. What is unclear, however, is whether this capacity depends on a unique constellation of perceptual and neurobiological mechanisms or whether a subset of such mechanisms is shared with other organisms. To explore this problem, parallel experiments were conducted on human newborns and cotton-top tamarin monkeys to assess their ability to discriminate unfamiliar languages. A habituation-dishabituation procedure was used to show that human newborns and tamarins can discriminate sentences from Dutch and Japanese but not if the sentences are played backward. Moreover, the cues for discrimination are not present in backward speech. This suggests that the human newborns' tuning to certain properties of speech relies on general processes of the primate auditory system.     

Ionization of liquids by radiation: measurement by charge scavenging

Pulse radiolysis of dilute solutions of triphenylcarbinol in saturated hydrocarbon gives spectra of the triphenylmethyl free radical, (C(6)H(5))(3)C., and cation, (C(6)H(5))(5)C(+). The yield of the ion is independent of the carbinol concentration, and is thought to measure the yield of free ions generated in the solvent. The relative yields of ions thus found in cyclohexane and 2,2,4-trimethylpentane agree with measurements made by the clearing-field method.     

Hardening by annealing and softening by deformation in nanostructured metals

We observe that a nanostructured metal can be hardened by annealing and softened when subsequently deformed, which is in contrast to the typical behavior of a metal. Microstructural investigation points to an effect of the structural scale on fundamental mechanisms of dislocation-dislocation and dislocation-interface reactions, such that heat treatment reduces the generation and interaction of dislocations, leading to an increase in strength and a reduction in ductility. A subsequent deformation step may restore the dislocation structure and facilitate the yielding process when the metal is stressed. As a consequence, the strength decreases and the ductility increases. These observations suggest that for materials such as the nanostructured aluminum studied here, deformation should be used as an optimizing procedure instead of annealing.