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1.
The sex expression of Lagenaria siceraria can be modified by phytohormones. This modification is related to "a certain bisexual stage" during floral bud differentiation. ACC (ethylene precursor) and STS (ethylene antagonist) can change the direction of sex differentiation of the floral buds in vitro. STS induces maleness by means of inhibiting ethylene action, directly promoting the development of the primordia of stamens, and then suppressing that of pistils. Hence, it can be deduced that ethylene induces femaleness by directly suppressing the development of the primordia of stamens and then promoting that of pistils. Such a regulation of the development of sexual organs is due to a change in the direction of assimilates to the pistils by ACC and to the stamens by STS. Therefore, ethylene induces femaleness by first limiting the sink strength of the stamens and then increasing that of the pistils.  相似文献   

2.
The inhibition of lingninase by hydrogen peroxide in the presence of cationic surfactant CTAB was studied by kinetic speetrophotometdc technique. Results showed that addition of CTAB enhanced the inhibition by H202, but it did not alter the inhibition pattern and the inhibition constant changed little with theco-ncentration of CTAB. Modification of the enzymic protein by the surfactant monomer may be responsible for the above mentioned results.  相似文献   

3.
In this paper,the relationship of intracellular acidification and apoptosis in Hela cells induced by vin-cristine sulfate has been studied by use of the ratiometric pH nanosensors that have been developed by our group,employing fluorescein isothiocyanate(FITC) doped as the pH-sensitive dye and Tris(2,2'-bipyidyl) dichlororuthenium(II) hexahydrate(RuBpy) doped as reference dye. The pH change of the Hela cells induced by vincristine sulfate has been monitored in vivo,in situ and real time by use of the ratiometric pH nanosensors. The experimental results show that the pH of the apoptotic Hela cells induced by vincristine sulfate has been acidified from 7.11 to 6.51,and the percentage of intra-cellular acidification is correlated with the induced concentration and incubation time of the vincristine sulfate. The further study of the percentage of intracellular acidification and the percentage of apop-tosis of Hela cells at the same time reveals that apoptosis of Hela cells induced by vincristine sulfate is preceded by intracellular acidification. These results would provide theoretical foundation for the therapy of cancer through interfering the pH of cells by use of vincristine sulfate or other anti-cancer drugs.  相似文献   

4.
雷西萍 《高分子科学》2012,30(6):808-814
Organo-fly ash(OFA) was prepared with pretreated fly ash(FA) and hexadecyltrimethyl ammonium bromide (HDTMAB),and the composites composed of OFA and polyaniline were obtained by emulsion polymerization at different OFA weight ratios(2.0 wt%,5.0 wt%,10.0 wt%,15.0 wt%and 20.0 wt%) in the presence of dodecylbenzenesulfonic acid as dopant and emulsifier.A polymerization procedure was supposed.The electrical conductivities of the composites were tested by the four-probe technique.The chemical structure and crystallinity of the composites were confirmed by FT-IR and X-ray diffraction,respectively.Morphologies of FA,OFA and the composites were observed by SEM.The element analysis was performed by energy dispersive spectrometry.The thermal stability of the composites was analyzed by TGA.The results showed that the electrical conductivity of the composites decreased with increasing the feed weight ratio of OFA,and the lowest value was 0.62 S/cm.HDTMAB and PAn were just adsorbed on the surface of FA and OFA,respectively according to the physical adsorption without destroying the crystalline structure of FA or OFA.The surface became smoother after organification of FA by using HDTMAB,and its content on FA surfaces was about 26.9 wt%.The core/shell structure of the composite was observed by SEM analysis.The composites showed a higher thermal stability than pure PAn by introduction of OFA into this polymerization system,the heat stability of PAn was increased by decreasing 31.8 wt%of weight loss after introducing 20 wt%of OFA.  相似文献   

5.
A strategy for the synthesis of polymer-protective bimetallic sols is proposed which has the advantage of the strong protective effect of the polymer agent on one of the composites to stabilize the bimetallic colloidal particles. This strategy is certified to be useful to the predication of the formation of stable bimetallic colloids protected by polymer and to the control of the particle size to a certain extent. A series of new PVP-protective bimetallic colloidal dispersions containing noble metal element (Pt, Rh, Pd), light transition metal element (Co, Fe), and boron are obtained from the corresponding salts by the methods of reduction by stage and coreduction, using the NaBH4 as reductant. The TEM, XRD and EPMA measurements indicate the formation of bimetallic colloids. An interesting kind of coil aggregation is observed in the systems of PVP-Pt-Co and PVP-Rh-Co prepared by the method of reduction by stage.  相似文献   

6.
In this paper, it is evidenced by the quantitative structu re-carcinogenic activity relation-ship (QSCAR) and the pattern recognition treatment of N-nitroso compounds (NNC) that thekey step of carcinogenesis induced by NNC is the cross-linking on the complementary basepair of DNA, through the bifunctional alkylation between α-carbon and another carbonwithin the same chain. The alkylation by the α-carbon atom is through the diazonium salt,but that by the atom other than the α-position is through the active ester formed from thehydroxylated metabolite of the chain. Therefore, the alkylation by the β-position of NNC,or by its γ-position under suitable conditions, of which the distances from the α-positionboth approach 2. 80-3. 00 A, would be the most favourable positions along with the α-posi-tion for the cross-linking to occur between the complementary base pairs of DNA, whichwill yield the carcinogenic activity of NNC. The above conception of bifunctional alkyla-tion can reduce the QSCAR of NNC to  相似文献   

7.
Study on the hydrogenation coupling of methane   总被引:4,自引:0,他引:4  
At atmospheric pressure and ambient temperature, the hydrogenation coupling of methane was studied by using pulse corona plasma and its synergism with catalyst. The results showed that (i) under pulse corona plasma, the coupling of methane could be fulfilled by the addition of hydrogen, and with the increase of the amount of hydrogen, the conversion of methane and the yield of C2 hydrocarbon increased, and the deposit of carbon decreased; (ii) the conversion of methane was affected by pulse voltage and repeated frequency; (iii) in the system, the addition of Ni/y-AI203 could improve the distribution of C2 hydrocarbon; (iv) the activity of Ni/y-AI2O3 prepared by cold plasma was better than that by chemical methods. The experiment opened up a new technical route of the coupling of methane.  相似文献   

8.
A giant earthquake of magnitude 9.0 occurred in Pacific Ocean off of Tohoku District Japan on March 11, 2011. The highest seismic intensity of 7 in JMA scale was recorded in Miyagi. In the Tohoku district, around 230 buildings are seismically isolated (hereafter, SI) mainly by elastomeric isolators (seismic rubber bearings). According to the official survey reports by several organizations (for example[1]), the records of those buildings have verified the effectiveness of the seismic isolation. The response acceleration of the SI buildings was reduced by 30% to 50% of the input ground acceleration. Additionally, the difference of the conditions inside the room between SI and the fixed-base buildings was obvious as well as the damage in main structures of the buildings. The displacements of the isolators by the earthquake were around 200 mm according to the records of the instruments. As a result, the performance of SI buildings and the elastomeric isolators in the Tohoku District―Off the Pacific Ocean Earthquake 2011 were excellent, and the efficiency of the seismic isolation was verified by the records of many buildings in wide area.  相似文献   

9.
Nano-structured SiO2 thin films were prepared on the surface of carbon steel for the first time by LPD. The compositions of the films were analyzed by XPS, and the surface morphology of the thin films were observed by AFM. The thin films were constituted by compact particles of SiO2, and there was no Fe in the films. In the process of film forming, the SiO2 colloid particles were deposited or absorbed directly onto the surface of carbon steel substrates that were activated by acid solution containing inhibitor, and corrosion of the substrates was avoided. The nano-structured SiO2 thin films that were prepared had excellent protective efficiency to the carbon.  相似文献   

10.
A water-soluble crude extract prepared from Ornithogalum caudatum Ait. (()CA) showing a high immunomodulating activitiy was isolated and characterized by virtue of gel filtration and column chromatography. The presence of the monosaccharides has been established by the chemical analysis. The quantitative analysis of the alditol acetate derivatives of them showed the ratios of the monosaccharides analyzed by means of GC respectively. The concentrations of protein(280 nm) and carbohydrate(496 nm) were detected respectively. The information of the molecular weight from the pure polysaccharide was obtained by several standard Dextrans from the Sephadex chromatography.  相似文献   

11.
The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.  相似文献   

12.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

13.
以α位(2,4-二特戊基)苯氧基邻苯二腈作为环合前体,制备了多种金属酞菁,产物经元素分析、紫外、红外、核磁氢谱等分析手段进行表征.并选择了部分酞菁进行溴化,其中着重研究了不同中心金属以及溴化对染料Q带吸收的影响.结果表明,酞菁染料的金属化对于其Q带吸收影响很大,多数染料金属化后会出现蓝移,而选择合适的条件进行溴化,可以使得金属酞菁的Q带吸收出现一定程度的红移,其中部分溴化金属酞菁的吸收波长与光信息产业中使用的近红外激光器很接近,具有潜在的实用价值.  相似文献   

14.
Trimethylsilylacetamide and trimethylsilyltrifluoroacetamide react with halogenodiorganylboranes to monomeric or dimeric amidoboranes depending on the organyl substituents. The compounds were characterized analytically and spectroscopically (NMR:1H,19F,11B; MS; IR).
21. Mitt.:A. Meller, W. Maringgele, K. Hennemuth undU. Sicker, J. Z. anorg. allg. Chem., im Druck.  相似文献   

15.
Góral, M. and Zawadzki, S., 1993. Vapour-liquid equilibria in nonpolar mixtures. II. Carbon tetrachloride with alkylbenzenes and n-alkanes at 313.15 K. Fluid Phase Equilibria, 90: 355-364.

Total vapour pressure measurements using a modified static method at 313.15 K are reported for binary mixtures of CCl4 with benzene, toluene, o-xylene, p-xylene, hexane, heptane, octane, nonane and decane. The results were correlated with the generalized Redlich-Kister equation for excess Gibbs energy. A comparison with literature vapour-liquid equilibrium data and excess enthalpy was made. Consistency within homologous series was checked. Predictions made using the UNIFAC method and the Hildebrand-Scatchard equation were compared.  相似文献   


16.
AgCuSe nanorods were prepared at room temperature by a redox reaction. The as-prepared product was characterized by X-ray powder diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy.X-ray powder diffraction shows that the as-prepared product is the tetragonal phase of AgCuSe. Transmission electron microscopy shows that the sample consists of nanorods with a diameter varying from 5 nm to 20 nm and a length varying from 200 nm to 600 nm. X-ray photoelectron spectroscopy shows that the purity of the sample is high. The formation mechanism of AgCuSe and the growth mechanism of AgCuSe nanorods were discussed.Thermodynamic calulations show that the final product in the synthetic system is pure AgCuSe. The solvent ethylenediamine did not only acts a didentate ligand to form relatively state Ag + and Cu + complexes, but also dissolved Se and enhanced the reactivity of Se. It played an important role in controlling the nucleation and growth of AgCuSe nanorods.  相似文献   

17.
Applying calculus to the horizontal and vertical unit hyperbolas we derive the obtuse exterior and the acute angle of parallelism formulas for the arc length of a unit circle. When the analogous arc length of a hyperbola is figured, we further define metric distance with radian measure. Employing a non-conventional velocity of light formula, we explain several aspects of physics with a logical geometry. The hyperbolic geometry Lobacevskii angle of parallelism is mathematically measured to agree with the physical measure, without using the gravitational constant, but rather the electromagnetic spectrum and geodesics. Space is hereby measured with units of radians and time. Half-angle formulas for slopes and boosts pertain to spinor algebra. The new light velocity is justified when its derivative results in Einstein's mass–energy formula. Relativity is reformulated with these half-angle formulas.  相似文献   

18.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.  相似文献   

19.
The results of studies carried out in the past five years on the gas-phase synthesis of organochlorosilanes, pentachlorodisiloxanes, organochlorogermanes, and organochlorostannanes at 400–550 °C in the presence of hexachlorodisilane or 1,1-dichloro-1-silacyclopent-3-ene as sources of dichlorosilylene are summarized. Dedicated to the memory of Academician M. E. Vol'pin timed to his 75th birthday. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1063–1070, June, 1998.  相似文献   

20.
Broadband dielectric spectroscopy is employed for the first time to study the molecular dynamics in discotic liquid crystalline polymers. One dielectric relaxation process is found which is strongly broadened and asymmetric. It is assigned a local hindered rotation of the ester groups attaching the spacer to the discotic mesogen. This assignment is supported by NMR measurements on the identical substance.Dedicated to Prof. E. W. Fischer on the occasion of his 60th birthday.  相似文献   

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