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81.
S. Bhattacharyya A. C. Das Ghosh D. P. Bhattacharyya Pratibha Pal 《Il Nuovo Cimento C》1991,14(5):463-472
Summary We have attempted here to study the nature of the sea-level cosmicmuon charge ratio at very high energies on the basis of
one particular model of multiple production of hadrons in which the violation of the Feynman scaling is one of the very gross
features. It is found that extreme emphasis on this feature alone would cause drastic departures from the experimental values
of the charge ratio; but when this is combined with some other recently observed and/or proposed characteristics of high-energy
interactions the model-based calculations agree quite well up to several TeV energy regime with the data. The model, in the
final analysis, supports a very feebly rising nature of the muon charge ratio at ultrahigh energy. 相似文献
82.
Lattice imaging technique of high resolution electron microscopy has been employed to examine 4H, 6H and 9R ABO3 perovskite polytypes. The lattice images can be correlated with the lattice periodicity and the stacking sequence of AO3 layers and BO6 octahedra. The study shows the utility and validity of the lattice imaging technique for the study of relatively close-packed
systems.
Commonwealth Visiting Professor, University of Oxford (1974–75). 相似文献
83.
Kapoor R Kataria A Venugopalan P Kapoor P Corbella M Rodríguez M Romero I Llobet A 《Inorganic chemistry》2004,43(21):6699-6706
The synthesis, structure, and magnetic properties of two new tetranuclear Cu(II) complexes containing N,N,N',N'-tetraethylpyridine-2,6-dithiocarboxamide (S-dept) of formula [Cu(2)Cl(2)(mu-S-dept)(2)][Cu(2)Cl(4)(mu-Cl)(2)] (1) and [Cu(2)(mu-Cl)(2)(S-dept)(2)][CuCl(3)(EtOH)](2) (2) are reported. Their X-ray crystal structures reveal that the complexes are composed of anionic and cationic dimers, that in both cases contain the metal centers which interact via Coulombic and/or hydrogen bonding interactions. In both cases, the Cu centers in the anionic moieties adopt a slightly distorted tetrahedral geometry whereas for the cationic moieties they adopt a square-pyramidal type of geometry. Magnetic susceptibility data show that compounds 1 and 2 present an overall antiferromagnetic behavior arising from the contribution of both anionic and cationic moieties. For 1, the best fit obtained gave J(1) = -2.62 +/- 0.19 cm(-1), J(2) = -19.54 +/- 0.47 cm(-1), and g(2) = 2.164 +/- 0.004 cm(-1) (R = 8.28 x 10(-5)) whereas for 2 it gave J(1) = 4.48 +/- 2.73 cm(-1), g(1) = 2.20 +/- 0.03, J(2) = -11.26 +/- 2.01 cm(-1), and g(2) = 2.10 +/- 0.03 (R = 1.15 x 10(-4)). The nature of the superexchange pathways in 1 and 2 is discussed on the basis of structural, magnetic, and molecular orbital considerations. Theoretical calculations are performed at the extended Huckel level in order to obtain their molecular orbitals and energies using their crystallographic data. 相似文献
84.
Sadashiva BK Reddy RA Pratibha R Madhusudana NV 《Chemical communications (Cambridge, England)》2001,(20):2140-2141
The synthesis and characterisation is reported of a low molecular weight organic compound to exhibit the biaxial smectic A (SmAb) phase, which shows a transition from the partial bilayer uniaxial SmAd phase to the SmAdb phase as the temperature is lowered. 相似文献
85.
A number of potent pyrimido[4,5-d]pyrimidine analogues have been efficiently synthesized by hetero Diels-Alder cycloaddition of 6-methyl-4-phenyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid methyl ester, a Biginelli compound with N-arylidine-N′-methylformamidines and N-arylidine guanidine in dry toluene. Structures of the newly obtained cycloadducts were established on the basis of elemental and spectral (IR, NMR and Mass) data. The molecular mechanism of the observed cycloaddition reaction has been investigated theoretically by means of PM3 semiempirical method. Transition state structure determinations and activation energy calculations have shown the preference for the endo approach over the exo approach of dienophile towards the diene fragments used, which is consistent with the experimental results. The studied cycloadditions proceed via an asynchronous concerted mechanism. It was demonstrated that FMO theory could reasonably predict the relative reactivities between dienes as well as indicating that these reactions belong to normal Diels-Alder type cycloadditions. 相似文献
86.
Effective potential model for calculating the energy shift in the ground state of two-electron atoms
Pratibha Jolly Kamalni Sane K. V. Sane 《International journal of quantum chemistry》1980,18(5):1223-1228
An effective operator for the electron–electron interaction derived earlier has been shown to be successful for calculating the ground-state energy shift values for 10 members of the helium isoelectronic sequence in terms of a single free parameter. Some possible applications of the modified interaction operator for semiempirical calculations are suggested. 相似文献
87.
Kapoor P Pathak A Kapoor R Venugopalan P Corbella M Rodríguez M Robles J Llobet A 《Inorganic chemistry》2002,41(23):6153-6160
The complexes [Cu2(mu-Cl)2(Cl)2(L)2] (L = dialkylpyridine-2,6-dicarboxylate; R = Et, L = depc, 1; R = i-Pr, L = dppc, 2) have been prepared and their magnetic properties studied. The crystal structures of complexes 1 and 2 have been solved. Compound 1 belongs to the P space group with Z = 2, a = 8.3020(10) A, b = 9.2050(10) A, c = 10.065(2) A, alpha = 99.040(10), beta = 100.810(10), and gamma = 106.502(10) whereas 2 belongs to the C2/c space group with Z = 8, a = 11.6360(10) A, b = 25.906(3) A, c = 11.76579(10) A, and beta = 107.900(10). The different alkyl ester substitutes produce substantial structural and electronic differences. The Cu2Cl2 core geometry is planar for 1 whereas it adopts a butterfly shape in the case of 2. Furthermore, in 2 the dppc ligand coordinates only by the carbonyl oxygen atoms whereas in 1 the depc ligand coordinates through carbonyl and alkoxy oxygen atoms. Magnetic susceptibility data show a ferromagnetic coupling between the two Cu(II) centers in both cases (J = 39.9(6) cm(-1) for 1, and J = 51.3(5) cm(-1) for 2) with very weak antiferromagnetic interactions (J ' = -0.59 cm(-1) and -0.57 cm(-1) for 1 and 2, respectively). Theoretical calculations at the extended Hückel level have also been carried out to further understand the electronic nature of complexes 1 and 2. 相似文献
88.
Singh RV Chaudhary P Poonia K Chauhan S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(3):587-594
Series of new trigonal bipyramidal and octahedral complexes of tin(IV) have been synthesized by the reaction of dimethyltin(IV) dichloride with 4-nitro-benzanilidethiosemicarbazone (L(1)H), 4-chlorobenzanilidethiosemicarbazone (L(2)H), 4-nitrobenzanilidesemicarbazone (L(3)H) and 4-chlorobenzanilidesemicarbazone (L(4)H). The unimolecular and bimolecular reactions of dimethyltin(IV) dichloride and monobasic bidentate ligands were carried out using microwave irradiations as the thermal energy source and the complexes so formed were characterized by elemental analysis, conductance measurements, molecular weight determinations and spectral data, viz. IR, UV-vis, (1)H and (13)C NMR. The complexes have also been prepared by the general thermal methods for comparison purposes. The comparison data support the synthesis using the microwave route, i.e. green chemistry route. The tin(IV) complexes show penta-coordinated structure for 1:1 complexes and hexa-coordinated for 1:2 complexes. The antifungal, antibacterial and antifertility activities have been examined and the results were indeed very encouraging. 相似文献
89.
Kapoor IP Srivastava P Singh G Singh UP Fröhlich R 《The journal of physical chemistry. A》2008,112(4):652-659
Three salts of phenylenediammonium diperchlorate have been prepared and characterized by X-ray crystallography. Their thermal decomposition has been studied by thermogravimetry (TG), differential thermal analysis (DTA), and explosion delay (DE) measurements. The kinetics of thermal decomposition was evaluated by model fitting and isoconversional methods using TG data. The oxidation-reduction reactions near the surface of thermolysing perchlorates may be responsible for the decomposition followed by explosion. The possible pathways of thermolysis have also been proposed. 相似文献
90.
In this paper we show that the closure of the space BMOA of analytic functions of bounded mean oscillation in the Bloch spaceB is the image P(U) of space of all continuous functions on the maximal ideal space ofH
under the Bergman projection P. It is proved that the radial growth of functions in P(U) is slower than the iterated logarithm studied by Makarov. So some geometric conditions are given for functions in P(U), which we can easily use to construct many Bloch functions not in P(U). 相似文献