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961.
Hong?Zhu Feng?Zhao Ji'an?Tang Jingru?Li Xingchang?Li Long?JiangEmail author 《科学通报(英文版)》2002,47(24):2056-2059
Oil-water interface layers dilatation rheological properties have been measured with the liquid-liquid interface film pressure measurement apparatus, which was based on the principles of Langmuir film balance. Experimental results show that it is possible to form the interface-associ- ated material caused by the attraction of the dispersion forces at the pure alkane-water interface. The type of material is sensitive to the interfacial pressure. Under the influence of the interfacial pressure, the stability of the interface associated materials decreases with the increase of the number of alkane carbons. 相似文献
962.
Zuoren?Yu Jikui?Guan Yehua?Ge Jing?Ma Rui?Guo Sai?Li Shepu?Xue Daishu?HanEmail author 《科学通报(英文版)》2002,47(24):2075-2079
The differentiation process of round spermatids to spermatozoa during the late stage of spermatogenesis is called spermiogenesis. To explore spermiogenesis-related genes, cDNA microarray was used to study expression patterns of 1176 genes in pachytene spermatocytes, round spermatids and elongating spermatids of Balb/c mice. The results showed that 208 genes were detected in all the three cell types. Most of them were down-regulated from pachytene spermatocytes to round spermatids and elongating spermatids. However, up-regulation of 7 genes expression in round spermatids and 3 genes in elongating spermatids were found. Expression of 7 differentially expressed genes in cDNA arrays was further confirmed by semi-quantitative RT-PCR study. The RT-PCR results indicated that the expression of 6 genes was consistent with that in cDNA arrays, only one gene did not show differential expression by RT-PCR. These results may provide important clues for studying of expression, regulation, and function of spermiogenesis-related genes. 相似文献
963.
The impact of habitat fragmentation and isolation on the genetic diversity of populations has attracted much attention in
studies of meta-population and conservation biology. In this work, using the randomly amplified polymorphic DNA (RAPD) technique,
we studied the genetic diversity of central, peripheral and peninsular populations of ratlike hamster, which were collected
in five locations of the North China Plain and its surrounding areas, in 1999. The study revealed that, i) the genetic diversity
of central population of Raoyang County>the sub-central populations of Gu’an County and Taikang County > the peripheral population
of Shunyi District>the peninsular population of Mentougou District; ii) the genetic diversities of the five populations were
positively correlated to the nearest distances to the peripheral line of population distribution; iii) there were significant
differences of gene frequencies of some RAPD fragments among the five populations. More RAPD fragments disappeared in peripheral
populations than in central or sub-central populations. The frequencies of two RAPD fragments were correlated to the latitude.
This study clearly indicated that the variation of the genetic diversities of the five populations was caused by edge effect
and fragmentation through the enhanced inbreeding and genetic drift, and thus supported the view that habitat fragmentation
and related edge effect reduce the population genetic diversity. 相似文献
964.
Yunhua?Wang Junxia?Lu Wenhu?Wang Yi?Ren Yi?Xie Zhongxian?HuangEmail author 《科学通报(英文版)》2002,47(24):2063-2066
To understand effect of π-stacking interactions between the side chain of aromatic amino acids and the porphyrin ring on structures
and properties in cytochrome b5 (cyt b5), the Phe58 residue was mutated to tyrosine and tryptophan, respectively by site-directed mutagenesis. The denaturation of
cyt b5 F58W and F58Y toward guanidine hydrochloride was examined by UV-visible and fluorescence spectroscopy. The kinetics of heme
transfer reactions between apo-myoglobin and the mutants were studied. The results indicated that the mutation of F58 residue
for Y58 or W58 reduced the interaction between of peptide and the heme group, resulting in decrease of the T
m and C
m values of the proteins, increase of the heme transfer reaction rate, and shifts of the redox potential. 相似文献
965.
Treatment of CptRh(PMe3)Cl2(1) (Cpt = 5(- tBu2C5H3) with [Et4N]2Se6 in DMF solution leads to the formation of cyclo-tetraselenido half-sandwich rhodium complexes CptRh(PMe3)(Se4) (2). The elimination of 2 with excess of nBu3P results in cyclo-diselenido rhodium complex CptRh(PMe3)(Se2) (3). 1 reacts with [nBu4N]2Te5 in DMF solution to yield cyclo-ditellurido rhodium complex CptRh (PMe3)(Te2) (4) in which carbon atom from CH2Cl2 can be inserted into Te-Te bond to form CptRh(PMe3)(TeCH2Te) (5). The new complexes 2-5 have been characterized by their IR, EI-MS, and 1H, 13C, 31P, 103Rh NMR spectra as well as elemental analysis. 相似文献
966.
The consistence between the first rapid cooling time (226-219 Ma) of the untrahigh pressure metamorphic (UHPM) rocks in the Dabie Mountains and the formation time (205-220 Ma) of the syncollisional granites in the Qinling and Sulu areas suggests that the first rapid cooling and uplift of the UHPM rocks may be related to breakoff of subducted plate. Therefore the second rapid cooling and uplift (180-170 Ma) of the UHPM racks needs a post-collisional lithosphere delamination which resulted in the granitic magmatism with an age of about 170 Ma. In addition, the rapid rising of the Dabie dome in the early Cretaceous (130-110 Ma) and the corresponding large-scale magmatism in the Dabie Mountains need another lithosphere delamination. The geochronology of the post-collis- ional mafic-ultramafic intrusions and geological relationship between the mafic-ultramafic intrusions and granites suggest that partial melting was initiated in the mantle, and then progressively developed in the crust, suggesting a mantle upwelling underneath the Dabie Mountains. The unusual fractional trend of the gabbros characterized by lower SiO2 content (46.24%) corresponding to lower MgO content (4.53%) and their typical geochemistry features of the lower crust suggest underplating of the mantle derived magma and interaction between the magma and lower crust before their intrusion. Lithosphere delamination could be the dynamic cause of the mantle upwelling and underplating. The seismic tomography results of the Dabie Mountains and adjacent areas clearly show lithosphere thinning below the north and south sides of the Dabie Mountains. Because there is no Cenozoic magma event in the Dabie Mountains, the lithosphere thinning may result from delamination of thickened lithosphere mantle after collision. In addition, both the lower velocity zone in the 40 km depth and the basin + dome + basin coupling relationship in the Dabie Mountains also suggest the lithosphere delamination and underplating on the two sides of the orogen. 相似文献
967.
Yi?Peng Shiping?YanEmail author Peng?Cheng Daizheng?Liao Zonghui?Jiang Genglin?Wang 《科学通报(英文版)》2002,47(6):461-463
Kinetic studies of the decomposition reaction of dinuclear Fe(Ⅱ) adducts [Fe2(N-Et-HPTB){O2P(OPh)2}](Cl- O4)2 (1) and [Fe2(N-Et-HPTB) {O2P(Ph)2}] (ClO4)2 (2) with O2 have been carried out at low temperature using UV-vis spectra. The decomposition reaction of Fe(Ⅱ)/O2 adducts was first-order in the experimental conditions, and the activation parameters were obtained. ?H¹ = 85.62 kJ·mol-1, ?S¹ = 19.43 J·mol-1·K-1 for compound (1) and ?H¹ = 97.97 kJ·mol-1, ?S¹ = 55.68 J·mol-1·K-1 for compound (2). These results are similar to those of dioxygen adducts of other metals complexes and natural enzymes such as methane mono- oxygenase (MMOH). 相似文献
968.
A high-resolution stalagmite O-C isotope record from Nanjing and its rapid response to climatic events 总被引:3,自引:0,他引:3
Here we discussed rapid response of the cave temperature and vegetation to the four Dansgaard-Oeschger cold and warm cycles
during 50-40 kaBP based on results of oxygen and carbon stable isotopic compositions from a stalagmite in Tangshan, Nanjing.
It is found that the amount of C3 vegetation relative to C4-type declines during the D-O warm events, indicating the decrease of the effective meteoric precipitation. Compared with
O-isotope records of the Greenland ice core, the stalagmite record displays a very similar pattern to Greenland ice core record
over the decade-century time scale, suggesting that the changes of the East Asian monsoon climate are in accordance with the
high-latitude polar climate in the short-term time scale. The age of the ice-rafted H5 event in the stalagmite record, however,
preceded that of Greenland ice cores by 2 ka. This out of phase between the remote areas cannot be yet proven because the
two time scales were determined from different dating methods. 相似文献
969.
四川灌县九甸坪剖面横切龙门山的懒板凳飞来峰。文章根据岩石特征、古生物特征对该剖面进行了岩石地层单位的划分,从中识别出下泥盆统甘溪组、上泥盆统茅坝组及下石炭统总长沟组,并与邻区相应地层进行了对比。 相似文献
970.
酸式电解法处理废蓄电池泥渣新工艺的研究 总被引:3,自引:1,他引:3
本文研究了一种从废蓄电池泥渣中湿法回收铅的新工艺,该工艺以K2CO3脱硫,以自研的复合还原剂还原,以氟硅酸作电解液电冶Pb.获得铅粉纯度达99.99%,电流效率>98%,铅直收率>95%,铅总回收率>98%,此外,工艺过程稳定,效率高,成本低,无环境污染。 相似文献