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991.
The ultraviolet photoelectron spectrum of the N-chlorothionylimide molecule (Cl-NSO) has been obtained and analyzed. The spectrum is interpreted by comparison with the known spectra of the parent compounds H-NSO, SO2 and the related molecules Cl-NCO and H-NCO as well as with the aid ofab initio SCF-calculations in terms of ionization from the eight highest filled valence molecular orbitals in this molecule.
  相似文献   
992.
Thirteen peptides, analogues of bradykinin (BK), enkephalin, Substance P (SP) and [Sar1]-angiotensin II ([Sar1]-ATII) have been synthesized by the solid-phase method. In all these peptides the residue Phe and Tyr were substituted with the boron-containing amino-acid L -o-carboranylalanine (Car). The purity and identity of the peptides were established by TLC., cellulose-electrophoresis and amino acid analysis.  相似文献   
993.
Experiments were designed to measure trace uranium concentration and the rate of radon exhalation from masonry structural materials, both bare and surface finished and coated. LR115 cellulose nitrate track detectors were used to record the alpha emission from structural material surface. Fission track, neutron activation and fluorometric analysis methods were used to determine the uranium content. Most types of paints studied will reduce alpha contribution and radon emanation from building materials.  相似文献   
994.
A generator of chemical structures (CONGEN) has been utilized to investigate two aspects of the structural isomerism of mono- and sesquiterpenoid skeletons: (1) the scope of possible isomers under various structural constraints; and (2) the scope of possible isomers based on a mechanistic model which allows interactive exploration of reactions of formation and interconversion. The possibilities, even under severe constraints, are many more than the structural types commonly encountered in natural. These results indicate the potential danger of structural assignment based in part on biogenic grounds.  相似文献   
995.
New oxidation-resistant hexaphenyl-substituted tetramethyltetraazachlorin, its nickel complex, and tetraphenyl-substituted octamethyltetraazabacteriochlorin and octamethyltetraazaisobacteriochlorin nickel complexes were synthesized for the first time by mixed condensation of diphenylm aleonitrile with tetramethylsuccinonitrile in the presence of lithium dimethylaminoethoxide or nickel chloride. The products were characterized by electronic absorption, 1H NMR, and mass spectra. Mixed condensation of diphenylsuccinonitrile with phthalonitrile in the presence of nickel chloride was found to give nickel complexes of phenylsubstituted benzo-fused tetraazaporphyrins rather than their hydrogenated derivatives.  相似文献   
996.
The oxidation of propene was studied on several tungsten oxides which contained small amounts of Ti, Ta, Nb and Sn. Only the Sn-containing specimen was found to be selective in the conversion of propene to acrolein. The catalytic results are correlated with crystal structures determined by electron microscopy.
, Ti, Ta, Nb Sn. , , Sn, . , .
  相似文献   
997.
The photochemistry of the stereoisomeric 1,3-dimethyl-3(2-phenylethenyl)cyclohexenes has been explored Direct irradiation of the cis- and trans-β-styrylcyclohexenes leads to di-π-methane rearrangement, producing the endo- and exo-3,7-dimethyl-8-phenybicyclo[5.1.0]oct-2-enes, and cis -trans isomerization, interconverting the 1,4-diene containing substrates. Triplet sensitized photolysis of both substituted cyclohexenes leads exclusively to cis-trans isomerization. Results from low conversion direct irradiations of the cis- and trans-β-styrylcyclohexenes indicate that the singlet rearrangements are stereospecific, and lead to formation of the 8-exo and 8-endo-phenylbicyclic octenes, respectively. The relationship between di-π-methane structure and triplet reaction efficiency, and the effect of conformation on the rearrangement stereochemistry are discussed.  相似文献   
998.
999.
Assuming that the separated pair ground state wave function of a 2N-electron system is already known a method is given for constructing a suitable orthogonal complement to the set of product functions built up from strongly orthogonal geminals. All terms are explicitly given which may have nonzero matrix element with the separated pair ground state. Using perturbational techniques a second order correction is calculated. In the case of Be atom the magnitudes of contributions from terms omitted in the generalized separated pair theory are estimated and found to be appreciable.
Zusammenfassung Unter der Annahme, daß der Grundzustand eines 2N-Elektronensystems in der Methode der getrennten Elektronenpaare bekannt ist, wird eine Methode angegeben, wie man den Basissatz von Produktfunktionen aus streng orthogonalen Geminalen geeignet vervollständigen kann. Alle mit dem Grundzustand kombinierenden Terme werden explizit angegeben. Mit Hilfe der Störungsrechnung wird eine Korrektur zweiter Ordnung berechnet. Im Falle des Be-Atoms wird die Größe der in der Theorie der getrennten Elektronenpaare vernachlässigten Beiträge abgeschätzt und als beträchtlich erwiesen.

Résumé Si l'on suppose connue la fonction d'onde à paires séparées pour l'état fondamental d'un système à 2N électrons, une méthode décrite ici permet de construire convenablement un complément orthogonal à l'ensemble des fonctions produits de géminales fortement orthogonales. Tous les termes ayant un élément dematrice non nul avec l'état fondamental sont donnés explicitement. Une correction du second ordre est calculée au moyen des techniques de perturbation. Dans le cas de l'atome de beryllium, la grandeur des contributions des termes omis dans la théorie généralisée des pair es séparées est estimée et trouvée non négligeable.
  相似文献   
1000.
1-Allenylpyrazole and 1-allenyl-1,2,4-triazole react with hydrogen chloride via proton addition at the pyridine-like nitrogen atom (N2 and N4, respectively). In the reaction with 1-allenylpyrazole, 1-[(E)-3-chloro-1-propenyl]pyrazole is also formed via regio- and stereoselective addition of hydrogen chloride to the propadienyl group. 1-Allenylpyrazole and 1-allenyl-1,2,4-triazole act as unidentate ligands with respect to Co, Ni, Cu, Zn, Cd, Pd, and Sn, the donor centers being N2 and N4, respectively. Apart from mononuclear coordination compounds, 1-allenylpyrazole gives rise to polymeric complexes which contain units and blocks formed by the free ligand.  相似文献   
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