The title compound of karounidiol (C30H48O2), a main active triterpene component of snakegourd seed, was isolated from unsaponifiable matter of the seed oil of Trichosanthes kirilowii Maxim., and characterized by X-ra...The title compound of karounidiol (C30H48O2), a main active triterpene component of snakegourd seed, was isolated from unsaponifiable matter of the seed oil of Trichosanthes kirilowii Maxim., and characterized by X-ray diffraction analysis. It crystallizes in orthorhombic system, space group P212121 with C30H48O2CH3OHH2O (C31H54O4), a = 7.515(1), b = 14.407(1), c = 27.799(2) , V = 3009.8(5) 3, Z = 4, Dx = 1.087 g/cm3, Mr = 490.77, F(000) = 1088 and = 0.086 mm-1. The final R = 0.0840 and wR = 0.2289 for 2752 observed reflections (|F|2 ≥ 2|F|2). The molecular crystal structure of karounidiol shows relative stereochemistry of (3,13,14, 20)-3,29-dihydroxy-13-methyl-26-norolean-7,9(11)-diene. The molecule is composed of five six- membered rings with ring junctures of A/B trans, C/D trans and D/E cis.展开更多
The catalytic effects of minerals (oxides) on solution loss reaction of coke were investigated in detail by adding oxides to coal which produces coke or absorbing oxides on coke surface. The mineral catalysis index ( ...The catalytic effects of minerals (oxides) on solution loss reaction of coke were investigated in detail by adding oxides to coal which produces coke or absorbing oxides on coke surface. The mineral catalysis index ( MCI ) which can be used to evaluate catalytic effects of minerals on solution loss of coke comprehensively was proposed. Using the volatility of coal in dry basis and MCI of coal as independent variables to control coke reactivity, the mathematical models of predicting coke reactivity index, coke strength of reactivity were constructed on the basis of the experimental results.展开更多
A model has been established for the interaction between a single-mode optical field and a 2-energy-level cold atom with exact analytic solutions given. The processes of momentum and energy exchanges between the optic...A model has been established for the interaction between a single-mode optical field and a 2-energy-level cold atom with exact analytic solutions given. The processes of momentum and energy exchanges between the optical field and the cold atom due to the interaction between them are discussed in detail, and a formula has been given for the variation of momentum and energy exchange volumes with time t in dress state while both the effects of photon recoil and Doppler effect are taken into consideration.展开更多
For the two-level atoms system interacting with single-mode active field in a quantum cavity, the dynamics of the Bose-Einstein Condensation (BEC) is analyzed using an ordinary method suggested by authors to solve the...For the two-level atoms system interacting with single-mode active field in a quantum cavity, the dynamics of the Bose-Einstein Condensation (BEC) is analyzed using an ordinary method suggested by authors to solve the system of Schrodinger representation in the Heisenberg representation. The wave function of the atoms is given. The stability factor determining the BEC and the selection rules of the quantum transition are solved.展开更多
The plantation occupies great proportion in urban forest in many cities in China. The design and managementforurban forest supplementseach other.Thedesign decides theorientation of management, while the management als...The plantation occupies great proportion in urban forest in many cities in China. The design and managementforurban forest supplementseach other.Thedesign decides theorientation of management, while the management also affects the landscape effects and ecological benefits of the design in reverse. There are many issues on design and management of urban forest. For example,somedesignsonly emphasizethe visualimpressionwhileignoring theecologicalbenefits, the problems of simplifying the forest layer structure and purifying its species composition are ubiquitous,It isshort ofcomprehensiveanalysisof local environment conditions, the phenomena are very outstanding in learning foreign or other city’s model by copying mechanically. The management model is not only monotonous, but also behind the step of urban development and thehuman demand for returning to nature.These unreasonable designs and managements areone of the main reasons for lower ecological benefits, and also caused some other bad aftereffects, such as lower biodiversity and high cost of management, etc. So the thought of close-to-nature design and management in urban forest is proposed and its feasibility and methods are discussed in the paper.展开更多
Trees are the main elements in urban forest construction, and their application directly reflects theconstruction level of urban forest. Two cities, Harbin and Hefei, were selected as representative middle citiesin th...Trees are the main elements in urban forest construction, and their application directly reflects theconstruction level of urban forest. Two cities, Harbin and Hefei, were selected as representative middle citiesin this article. The application of tree species was analyzed by contrast in urban forest construction, and theirapplication in Hefeis different land types was stressed. Based on this, the application of tree species wasfurther discussed during the process of urban forest construction in China. Thus it provided references for thenational urban forest construction.展开更多
基金the State Science and Technology Commission (No. 96-903-02-02)
文摘The title compound of karounidiol (C30H48O2), a main active triterpene component of snakegourd seed, was isolated from unsaponifiable matter of the seed oil of Trichosanthes kirilowii Maxim., and characterized by X-ray diffraction analysis. It crystallizes in orthorhombic system, space group P212121 with C30H48O2CH3OHH2O (C31H54O4), a = 7.515(1), b = 14.407(1), c = 27.799(2) , V = 3009.8(5) 3, Z = 4, Dx = 1.087 g/cm3, Mr = 490.77, F(000) = 1088 and = 0.086 mm-1. The final R = 0.0840 and wR = 0.2289 for 2752 observed reflections (|F|2 ≥ 2|F|2). The molecular crystal structure of karounidiol shows relative stereochemistry of (3,13,14, 20)-3,29-dihydroxy-13-methyl-26-norolean-7,9(11)-diene. The molecule is composed of five six- membered rings with ring junctures of A/B trans, C/D trans and D/E cis.
基金Item Sponsored by National Key Fundamental Research Development Project of China(1998061500)
文摘The catalytic effects of minerals (oxides) on solution loss reaction of coke were investigated in detail by adding oxides to coal which produces coke or absorbing oxides on coke surface. The mineral catalysis index ( MCI ) which can be used to evaluate catalytic effects of minerals on solution loss of coke comprehensively was proposed. Using the volatility of coal in dry basis and MCI of coal as independent variables to control coke reactivity, the mathematical models of predicting coke reactivity index, coke strength of reactivity were constructed on the basis of the experimental results.
文摘A model has been established for the interaction between a single-mode optical field and a 2-energy-level cold atom with exact analytic solutions given. The processes of momentum and energy exchanges between the optical field and the cold atom due to the interaction between them are discussed in detail, and a formula has been given for the variation of momentum and energy exchange volumes with time t in dress state while both the effects of photon recoil and Doppler effect are taken into consideration.
文摘For the two-level atoms system interacting with single-mode active field in a quantum cavity, the dynamics of the Bose-Einstein Condensation (BEC) is analyzed using an ordinary method suggested by authors to solve the system of Schrodinger representation in the Heisenberg representation. The wave function of the atoms is given. The stability factor determining the BEC and the selection rules of the quantum transition are solved.
文摘The plantation occupies great proportion in urban forest in many cities in China. The design and managementforurban forest supplementseach other.Thedesign decides theorientation of management, while the management also affects the landscape effects and ecological benefits of the design in reverse. There are many issues on design and management of urban forest. For example,somedesignsonly emphasizethe visualimpressionwhileignoring theecologicalbenefits, the problems of simplifying the forest layer structure and purifying its species composition are ubiquitous,It isshort ofcomprehensiveanalysisof local environment conditions, the phenomena are very outstanding in learning foreign or other city’s model by copying mechanically. The management model is not only monotonous, but also behind the step of urban development and thehuman demand for returning to nature.These unreasonable designs and managements areone of the main reasons for lower ecological benefits, and also caused some other bad aftereffects, such as lower biodiversity and high cost of management, etc. So the thought of close-to-nature design and management in urban forest is proposed and its feasibility and methods are discussed in the paper.
文摘Trees are the main elements in urban forest construction, and their application directly reflects theconstruction level of urban forest. Two cities, Harbin and Hefei, were selected as representative middle citiesin this article. The application of tree species was analyzed by contrast in urban forest construction, and theirapplication in Hefeis different land types was stressed. Based on this, the application of tree species wasfurther discussed during the process of urban forest construction in China. Thus it provided references for thenational urban forest construction.
