视网膜母细胞瘤基因产物部分性质的研究

研究Ｒｂ基因产物的代谢动力学和功能调节，发现整个细胞周期中都有Ｒｂ蛋白合成，其含量随细胞周期进行而变化，蛋白代谢的半衰期约为１１—１２小时，有非磷酸化和多种程度磷酸化形式。Ｒｂ蛋白的磷酸化水平是随细胞周期过程和细胞生长状态而变化的，在Ｇ０、Ｇ１期蛋白处于低磷酸化状态，到达Ｇ１／Ｓ界限，细胞获得磷酸化Ｒｂ蛋白的能力．     

稻纵卷叶螟幼虫寄生性天敌的种群特征与多样性分析(英文)

水稻卷叶螟的田间种群包括三个种,即稻纵卷叶螟(Cnaphalocrocis medinalis),和 MarasmiaPatnalis,M.exigua。1989年雨季在菲律宾吕宋岛上两个点进行的试验共分别记录了15(内湖省)和12(中吕宋)个种的幼虫寄生性天敌,它们分别攻击寄主卵～幼虫、幼虫和幼虫～蛹期,这些寄生性天敌分属于外寄生或内寄生,单寄生或多寄生,这种生物学特征上的差异为寄生性天敌提供了降低寄主种群的广大的机会。进一步的调查显示,那些攻击低龄寄主的种类具有高繁殖力的小个体的特征,而攻击高龄寄主的种类具有较宽的寄主范围且常常发育历期较短。多数天敌寄生于2或3龄幼虫,将寄主杀死于5龄之前,优势种及寄生率随寄主密度和水稻的生长期不同而变化。 根据Hill(1972)的多样性序列指数分析指出,当以N_2为标准时,在内湖省的整个水稻生育期内始终仅有2—3个种为极优势种,其数据适于用几何或对数序列进行描述。两个点的寄生性天敌种群多样性(N_2)接近于常数3—4,均匀度(E_5)与寄主幼虫密度呈负相关。因此,幼虫的寄生作用可被认为是一个抑制并稳定水稻卷叶螟田间种群的关键因子。     

Oscillation and noise determine signal transduction in shark multimodal sensory cells

Oscillating membrane potentials that generate rhythmic impulse patterns are considered to be of particular significance for neuronal information processing. In contrast, noise is usually seen as a disturbance which limits the accuracy of information transfer. We show here, however, that noise in combination with intrinsic oscillations can provide neurons with particular encoding properties, a discovery we made when recording from single electro-sensory afferents of a fish. The temporal sequence of the impulse trains indicates oscillations that operate near the spike-triggering threshold. The oscillation frequency determines the basic rhythm of impulse generation, but whether or not an impulse is actually triggered essentially depends on superimposed noise. The probability of impulse generation can be altered considerably by minor modifications of oscillation baseline and amplitude, which may underlie the exquisite sensitivity of these receptors to thermal and electrical stimuli. Additionally, thermal, but not electrical, stimuli alter the oscillation frequency, allowing dual sensory messages to be conveyed in a single spike train. These findings demonstrate novel properties of sensory transduction which may be relevant for neuronal signalling in general.     

Effects of 2,3,7,8-TCDD and benzo[a]pyrene on modulating vitellogenin expression in primary culture of crucian carp （Carassius auratus） hepatocytes

Vitellogenin (Vtg) is the precursor of yolk protein. Its expression and secretion are estrogen-regulated and are crucial for oocyte maturation. An in ritro xenoestrogen screening model was established by measuring Vtg induction in cultured primary hepatocytes from crucian carp. Vtg production was detected by biotin-avidin sandwich ELISA method while Vtg and cytochrome P4501A1 (CYP1A1) mRNA induction were measured by semi- quantitative PCR-primer dropping technique. Vtg and Vtg mRNA were dose-dependently induced by diethylstilbestrol (DES, 0.2-200 ng/mL) in hepatocytes of crucian carp. Co-treatment of the DES-induced hepatocytes with either 2,3,7,8-TCDD (TCDD, 0.1-4 pg/mL) or benzo[a]pyrene (B[a]P, 5-1000 ng/mL) resulted in a reduction of Vtg production and an increment of CYP1A1 mRNA expression both in a dose dependent manner, indicating the anti-estrogenic effects of the compounds. However, at lower tested concentrations, TCDD (0.1, 0.2 pg/mL), B[a]P (5 ng/mL)seemed to have a potentiating effect on Vtg expression and secretion, although by their own these compounds had no observable estrogenic effect on Vtg induction. Tamoxifen (a selective estrogen receptor modulators, 1 nmol/L-1μmol/L),and β-naphtho-flavone (β-NF, an aryl hydrocarbon receptor inducing compounds, 2.5-1000 ng/mL) also were employed to study the possible interactions in DES-induced Vtg expression. In co-treatment of the DES-induced hepatocytes with β-NF or tamoxifen, the decrease in Vtg production did parallel induction of CYP1A1 for β-NF, but tamoxifen inhibited Vtg induction did not parallel induced CYP1A1 expression in all test concentrations. On the contrary, it was found that in co-treatment of the TCDD-induced hepatocytes with DES, TCDD induced CYP1A1 mRNA production was inhibited by DES also. These results implicated a possible cross talk between estrogen receptor- and aryl hydrocarbon receptor-mediated pathways in the hepatocytes.     

燃烧系统的动力学

燃烧系统是可压缩流体中发生燃烧散热过程的场，在场的周围有边界条件的约束，内燃机中的汽缸和气轮机与火箭的燃烧室就是典型的燃烧系统的例子。本书全面地论述燃烧系统的动力学特性。     

利用花粉资料重建加拿大1 ka来气温变化序列

植物花粉资料用来恢复千年-万年尺度的气候变化是一种比较成熟的方法，并取得了大量的成果，但应用于十年至百年尺度的气候序列重建仍属探讨性研究，本文采用花粉资料，以50a为时间尺度单元，对加拿大过去1ka的温度进行了历史重建，近千年来北美地区气候环境受人为干扰甚少，1～0.1ka尺度的气侯变化主要受自然因子控制，因此可为认识和鉴定中国千年来气候变化序列中人为影响程度提供有价值的参照系，此外，本文所采用的花粉-气候转换法可以为中国的千年尺度的气候重建提供实用技术。     

The surface pollen and relative pollen production of the desert vegetation of the Alashan Plateau, western Inner Mongolia

This preliminary investigation focuses on the comparison of the recent pollen precipitation and its related vegetation of eight different plant communities in the Alashan Region, the most western part of the Inner Mongolia Autonomous Region. Most zonal and azonal communities can be well identified by their pollen spectra. Relative pollen production factors of various plant taxa have been calculated and the following sequences from over-to under represented taxa have been found for zonal vegetation: Chenopodiaceae,Artemisia, Ephedra, Nitraria, Reaumuria, Calligonum, Zygo-phyllum; and for azonal vegetation: Peganum, Populus,Tamarix, Lycium.     

Effect of Nano－SiC and Nano－Si Doping on Critical Current Density of MgB2

The discovery of superconductivity in magnesium diboride (MgB2) has opened up a new field in materials science research. It offers a possibility of a new class of high performance superconducting materials for practical applications because of the relatively low cost of fabrication, high critical current densities (Jc)and fields, large coherence length, absence of Weak links, higher Tc (Tc = 39 K) compared with Nb3Sn and Nb-Ti alloys (two or four times that of Nb3Sn and Nb-Ti alloys). However, the weak flux pinning in the magnetic field remains a major challenge. This paper reports the most interesting results on nenomaterial (SiC and Si) doping in magnesium diboride. The high density of nano-scele defects introduced by doping is responsible for the enhanced pinning. The fabrication method, critical current density, microstructures, flux pinning and cost for magnesium diboride bulks, wires and tapes are also discussed. It is believed that high performance SiC doped MgB2 will have a great potential for many practical applications at 5K to 25K up to 5T.     

Specific structural features of LnZrOx (Ln: La, Sm) mixed oxides prepared by different methods

LnZrOx(Ln: La, Sm) mixed oxides of Ln: Zr = 1 were prepared by different methods(complex polymerized method, sorption of cations on starch from aqueous salt solution and conventional co-precipitation with additional redispersion of precipitate by ultra sound) and calcined at 700–1300 °C. Their specific structural features and changes were studied and discussed. Various characterization methods were used such as X-ray diffraction,Electron microscopy, Fourier-transform infrared and Raman spectroscopy, UV–Vis spectroscopy, X-Ray absorption fine structure and X-ray photoelectron spectroscopy.The formation of pyrochlore structure occurred at 1100–1300 °C from fluorite-like pseudocubic phase ZrO_2 regardless the method of preparation. This phase had a block-like structure consisting of ZrO_2 nanocrystals stabilized by Ln cations and residual anions such as hydroxyls and carbonates. The desorption of such anions with heating already started at 900 °C and lead to local changes of Zr cations coordination to octahedral and to the formation of pyrochlore nanodomains inclusions within fluorite-like phase. The increased cation mobility and further elimination of anions caused by further heating was accompanied by the formation of bulk pyrochlore phase at 1100–1300 °C. Even after calcination at 1300 °C the local microheterogeneity as well as defects were identified at domains boundaries or sintered microstructure. These specific features of the formed pyrochlores depend on the method of preparation.     

非人类灵长目动物营养缺乏性贫血的研究

本文的目的是评述以往非人类灵长目动物因不适当的饲料自发,或者缺乏某种营养物饲料诱发的贫血症的研究。其中包括因铁、烟酸,维生素B_6,泛酸,蛋白质,核黄素,维生素B_(12),叶酸,维生素C和维生素E缺乏引起的贫血。对每一种营养物缺乏而诱发的贫血症的讨论着重于临床症状,以及外周血液和骨髓的病理学,也讨论了诱发缺乏症后,在饲料中添加营养物的结果。不论什么时候运用,这一讨论包括利用非人类灵长目动物作为研究人类相似的营养缺乏症的动物模型。发展中的灵长目动物商品饲料的许多理论基础,不幸地是根据经验,或从恒河猴的许多资料中推算得到的。对许多营养物而言,尚未用实验使动物产生缺乏综合症,至少还未报道过。本文的目的是评述过去关于非人类灵长目动物由于饲喂不合理的饲料而自然发生的贫血症,或者是由于饲喂了缺乏某些特殊营养物的饲料而诱发产生的贫血症的研究。综述中的许多研究资料是通过单一的或“纯”的某种营养物缺乏症的产生而获得的。研究中利用了非人类灵长目动物作为实验模型。由于普遍地大量饲用灵长类商品饲料和减少引入捕获的野生动物以及随之而来的营养缺乏,使目前非人类灵长目动物自发产生的贫血症比过去少得多。人类营养性贫血仍是一个问题,儿童尤为严重。因而,非人类灵长目动物作为一种动物模型,应该继续运用于在人类中见到的类似的贫血症产生的研究。