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1.
THE development of the theory of molecular structure and thenature of the chemical bond are discussed.Particular atten-tion is given to the theory of hybrid bond orbitals.  相似文献   

2.
In the linear inversion of the radial variation of the parameters of the Earth by usingthe observed frequencies of various normal modes of free oscillation of the earth, it is neces-sary to know the values of the kernels of the parameters ρ, μ and λ. This paper describesthe methods of the derivation of the formulas of these kernels. This is the first part of thepaper in which only the toroidal oscillations are considered. They are much simpler thanthose of the spheroidal ones, that we will consider in the second part of the paper. The data of the two types of oscillations are equally important in the solution of theinversion problem, and should be employed simultaneously, and we know that the toroidaloscillations are much simpler than the spheroidal ones, it seems wise to divide the whole programof the inversion problem into steps: first, by employing the toroidal data to correct the twoparameters ρ and μ in the mantle, then by using the spheroidal data to correct the remain-ing parameters, i.e. th  相似文献   

3.
Studies using electrophysiological and HRP-labeling techniques showed that the lateral border ofphysiologically determined primary visual cortex coincides with the cytoarchiectonically defined area 17/18a border. The dense callosal projections are distributed in a zone, about 1.5 mm wide, along this border,which lies in the callosal zone, about 1/4-1/3 of the zone width from its lateral limit. There are tworepresentations of the vertical meridian of the visual field, one in the proper of area 17, about 1/3 ofthe zone width from its medial limit, the other in area 18a, at about the lateral zone limit.  相似文献   

4.
In attempting to study the phototherapeutic action and the photosensitized oxygenation mechanism, we have determined the crystal structure of the main oxidized product of hypocrellin A (HA). It was crystallized in monoclinic system with space group P2_1. The cell data are: a=10.030(3), b=8.877(3), c=15.764(5), β=104.50(2)°, Z=2. The crystal structure has been determined by direct method and refined to a final R of 0.055 based on the 1408 observed reflections with l>2.5σ(Ⅰ). The photooxidized product is composed of a heptacyclic aliphatic hydrocarbon connecting with two α-naphthoquinone derivatives as its skeletal molecule. No peroxidic linkage has been found. On the basis of the crystal structure determined, we have deduced part of the process of formation of the oxide, ⅰ. e. firstly, the peroxide was formed by photocycloaddition of oxygen molecule to Hypocrellin A, then thermodissociation took place to form a stable oxide.  相似文献   

5.
This is the second instalment of the paper, in which the method of derivation of the for-mulas of parameter kernels for the spheroidal oscillations are considered. The principle ofRayleigh is used to derive the formulas of the kernels of the two elastic parameters, i.e. μand λ. But for that of ρ, it is found very difficult to get satisfactory results. A new butsimpler approach is followed and very satisfactory results are obtained.  相似文献   

6.
THESTUDYOFTHESYNTHESESOFTHEDERIVATIVESOFPOLYPHENYLENEANDTHEIRCONDUCTIVITY¥YinKuiLl;QingZiLIU;SanHUANG;TieFengWEN;ShangYouZHOU...  相似文献   

7.
The process of emulsifier-free copolymerization of the Styrene-Butyl Acrylate-K_sS_sO_s-water in thepresence of Barium Sulfate(BS)powder was investigated under varied conditions within the range of BSpowder quantity,initiator concentration and reaction temperature.Experimental results showed thatthe rate of polymerization is proportional to 0.3-power of the BS quantity and 1.3-power of theinitiator concentration.There is a linear relationship of 2/3-power for the conversion and time.Aprocess for the polymerization is propose to explain the experimental results.  相似文献   

8.
In this paper, a topography forced quasi-geostrophic baroclinic model and an SST (sea surface temperature) equation are used to set up a simple coupled atmosphere-ocean model The large-scale ocean current is nearly the Sverdrup flow. Two basic processes are considered in this system, i. e. the SST as a thermal forcing drives the atmospheric circulation and the ocean current produced by the wind redistributes the SST. Highly truncating and multiple scale method are used to simplify the model and obtain a low dimensional dynamic system. In this part, the qualitative vector in the phase space of the system is analysed and two stable equilibria are obtained. These two kinds of equailibria may be used to explain some features of the long-range anomalies of circulation.  相似文献   

9.
The Rat 3-3 is a secondary transformant of the rat fibroblast cell line (Rat-1) transfectedwith total DNA of a gastrocarcinoma cell line BGC-823. The cells over-express the c-Ha-rasoncogene which contains point mutation at the 12th codon. In order to determine how theactivated c-Ha-ras oncogene expression governs the cell's transformation, two pendadecadeoxy-nucleotides AS-1 and AS-2 were synthesized. AS-1 was complementary to the single strandof the first three codons and the upstream sequence close to the ribosome binding site of c-Ha-ras mRNA. AS-2 was complementary to the 3' end of the first intron and the 5' end ofthe second exon of c-Ha-ras unripe RNA enclosed in the nucleus. The oligonucleotides couldblock either the translation of c-Ha-ras mRNA or the splicing of c-Ha-ras unripe RNA, thusinhibiting the expression of the activated c-Ha-ras oncogene and the proliferation of thetransformed cells Rat 3-3. The inhibitory effect increased with a growing concentration ofthe antisense oligodeoxynucleoti  相似文献   

10.
The mechanism of the thermolysis of thietane to form ethyleneand thioformaldehyde has been studied by using ab initio SCF MO methodat STO-3G* and 3-21G* level.It has been found that there are twopossible stepwise pathways.One is to break C-C bond firstly,while theother is to break C-S bond at first.The cleavage of C-S bond is pre-ferred over that of C-C bond.  相似文献   

11.
A series of gorges on the lower reaches of the Yarlung Zangbo River is like an enormous crevice splitting the southeastern Qinghai-Xizang (Tibet)Plateau to create a passage through which warm, wet air flow from the Indian Ocean reaches the inner part of the plateau. This moisture passage was mainly strengthened after the Pleistocene epoch in the Quaternary period and has played a major role in affecting the beginning date of the rainy season and the amount of the plateau's rainfall. It has also served as a corridor for the living things on the southern and the northern sides of the Himalayas to mingle with each other. The region along this passage is abundant in evidences of species of differentiation, variation and biological division. Also the passage has provided a favorable environment for human beings and affected natural phenomena there.  相似文献   

12.
The amidoximation process of commercial polyacrylonitrile fiber was studied. The results showed that it is possible to prepare a chelating fiber, which present high adsorption capability to Au^3+ and reasonable mechanical property,by the amidoximation of PAN fiber,with the increase of reaction time or agent concentration,the coversion of CN group in PAN increases rapidly at first and then increases slowly.When the reaction temperature is higher than that at which the paracrystalline region in the fiber is destroyed, the conversion of CN group increases greatly,but the mechanical property of the fiber begins to be inferior.  相似文献   

13.
In this paper, the morphology, sedimentary structure, bioherm--building mollusk assem-blages and their growing and piling-up models of modern oyster bioherms in the estuariesof the Zimaigou and Xiaoqing Rivers are described and expounded, the environmentalconditions for the development of oyster bioherms, such as the dynamical geomorphicbackground, water depth, hydrodynamic factors and ecological conditions in the estuaries,are analyzed, the relationship of the successively seaward migrating of oyster biohermswith average annual sea-level changes and the erosion--accretion processes in the estuariesare probed and explained, and the geological significance of oyster bioherms in the studyof Quaternary marine environmental evolution is presented.  相似文献   

14.
The isolated liver nuclei and the mature sperm nuclei from Rana nigromaculata and Bufo bufo asiaticus had been investigated by indirect immunofluorescenee method with anti serum specific to the spindle fiber attachments (SFAs) from the scleroderma patients with CREST syndrome. It was found that in the isolated liver nuclei and the mature sperm nuclei of these animals there are discrete speckles which bind the antibody specific to the SFAs. The maximum number of these speckles counted in a single sperm nuclei of the frog corresponds with the haploid chromosome number of this animal (n=13). The haploid chromosome complement of the toad is 11 and the maximum number of the speckles counted in a single sperm nucleus of this species is also 11. These findings suggest that the scleroderma serum can be used to identify the SFAs of the amphibias and the antigens of SFAs are conserved in the mature sperms of these animals. The implication of these conclusions is discussed.  相似文献   

15.
A kind of the conditional instability of the second kind (CISK)--overstability convec-tion presented in the hurricane model is investigated in this paper. The structure of thisunstable mode and the basic conditions to excite it are also shown for discussion. In the tropical atmosphere, the cumulus convection could excite the CISK oscillatoryunstable mode through the CISK mechanism, and the cumulus friction (cumulus momentummixing) gives a fundamental effect to produce this overstability convection. Some meteorologists assumed that the waves in the lower stratosphere in the tropicalatmosphere may be caused by the forcing of the condensation heating. The present investi-gation shows from the dynamic angle that the CISK-overstability convection excited by thecumulus convection heating, especially by the cumulus momentum mixing, through the CISKmechanism is a fundamental factor to drive the waves in the equatorial stratosphere and theoscillatory phenomena in tropical atmosphere.  相似文献   

16.
The molecular weight separation and column dispersion for a number of SEC columns packedwith various packing materials were calibrated simultaneously using narrow MWD polystyrene stan-dards as probe. The molecular weight dependence of the spreading factor is closely related to thesurface structure in the pore of packings.  相似文献   

17.
The Lys fragment of mung bean trypsin inhibitor can combine with bovine trypsin to form a complex at an equal molar ratio. The single cxystals of the complex were obtained by using the micro-still-setting method and the X-ray diffraction extended to 1.8 resolution. Its space group is P2_12_12_1 wlth cell dimensions α=62.9(1), b=63.4(1) and c=69.7(2). There is one complex molecule in a crystallographic asymmetric unit.  相似文献   

18.
According to the result of the studies of the Taigu genie male-sterile wheat of the predecessor, a series of inductive inference was made at first. We used the Taigu genic malesterile wheat to make cross with rye to produce polyhaploid plant. By chromosome doubling, the dominant male-sterile gene became homozygous under artificial condition. The result of the experiment obtained shows that the expression and segregation ratio of the stamens of the haploid, amphiploid and the hybrid progenies of amphiploid plants well correspond to the inductive inference, so it confirms once again that a single dominant gene determines the male-sterility of the Taigu genic male-sterile wheat.The authors verify that the Tal gene not only can be expressed normally in common wheat's genetic background, but also can be introduced into the octoploid triticale. The first dominant genic male-sterile octoploid triticale is produced and has been used in triticale breeding program.  相似文献   

19.
The course of the polypeptide chain of Trichosanthin has been determined from the electron density map at 4 resolution. The structure belongs to α+β type. It contains eight α-helices (39% of total residues) and four β-sheets (32% of total residues) which are made up of thirteen β-strands. The α-helices are relatively in the centre of the molecule and surrounded by β-sheets. This is the characteristic feature of Trichosanthin structure. This kind of structural arrangement has not been reported before. The transformation matrix and translation vector, which superpose two molecules in one asymmetric unit, were obtained. The root mean square error is 1.31 for this superposition.  相似文献   

20.
Using 43 documented drill core samples of the H_5-chondrite "Jilin" the depth profile of GCR-and fission track densities was established. The track profile essentially reflects the GCR-track record of the second (4π-) irradiation stage of "Jilin". Relics of the track record of the first (2π-) exposure are indicated by a deviation from the theoretical depth profile of the 4π-exposure. No Pu-244 fission is observed ia the fission track background near the meteorite center. The atmospheric ablation thickness of the two drill cores A and B normal and parallel to the assumed surface of the "Jilin" parent body was found to be 11±4 cm, respectively. A minimum shielding depth of the "top" part of core A during the 2π-exposure is estimated to be~30 cm. Near surface deviations of the experimental track data from theory are ascribed to a short-term moderate heating event (equivalent to 24h,~370℃) no more than 0.4 Ma ago. The resulting partial track annealing in a surface layer of ~15—20 cm thickness of t  相似文献   

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