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41.
We construct a supersymmetric left–right model in four dimension with gauge-Higgs unification starting from a SU(3)c×SU(4)w×U(1)B−L gauge symmetry in five dimension. The model has several interesting features, such as, the CKM mixings in the quark sector are naturally small while for the neutrino sector it is not, light neutrino masses can be generated via the seesaw mechanism in the usual way, and the model has a U(1)R symmetry which naturally forbid dimension five proton decay operators. We also discuss the grand unification of our model in SO(12) in five dimensions. 相似文献
42.
A homopolymer of methyl methacrylate (MMA) and its copolymer with styrene at different compositions were synthesized and characterized.
Viscosity measurements of the synthesized homopolymer and the copolymers in toluene solutions were performed at 313 K. Different
equations were used to calculate the intrinsic viscosity, viscometric constants values, and molecular weight of the synthesized
polymers. The values of intrinsic viscosity and viscosity average molecular weight obtained by the two methods (single point
determination and graphical extrapolation) were compared in order to verify the validity of the single point determination
for the polymers. Viscometric properties derived included the specific viscosity (it determines the contribution of the solute
to the viscosity of the solution), the reduced viscosity (that provides a measure of the polymer capacity for increasing the
solution viscosity), and the intrinsic viscosity. 相似文献
43.
Zhenyu Chen Yuexing Liu Nandi Zhou Qiao Zhang Kun Han 《Journal of Analytical Chemistry》2011,66(7):642-645
Differential pulse voltammetry was used to study the formation and level of thymine dimer in DNA duplex modified on a gold
electrode. The electrochemical signal of methylene blue coupled with ferricyanide can be obtained via DNA mediated electron
transfer, which would be blocked during the formation of thymine dimer. DNA duplexes with different sequences differ in the
level of thymine dimer under the same UV irradiation. Futhermore, the presence of guanine base directly preceding -TT- can
effectively decrease the level of thymine dimer, possibly due to the self-repair process in which guanine participates. The
proposed method can be further applied to DNA self-repair analysis. 相似文献
44.
Three new bicomponent hydrogels of riboflavin (R) with salicylic acid (S), dihydroxybenzoic acid (B) and acetoguanamine (D) in 1:1 molar ratio have been reported. FTIR and UV-vis spectra suggest formation of H-bonded complexes in 1:1 molar ratio of the components. The network consists of tape, bar and helical tubes for RB11, RS11 and RD11 systems, respectively. Reversible first order phase transition and invariant storage modulus (G') with angular frequency (ω) characterise the systems as forming thermoreversible hydrogels. The RD11 gel has the highest gel melting temperature and highest critical strain compared to other gels. WAXS study indicates different crystal structures for different gels. NMR spectra reveals higher shielding of protons in RD11 gel suggesting better π-stacking compared to RS11 and RB11 gels. RD11 gel shows two-fold enhancement of photoluminescence (PL) intensity with a substantial red shift of emission peak but RB11 and RS11 gels show PL-quenching. The gels exhibit a small decrease in lifetime and the PL property is very much temperature and pH dependent. So the complementary molecules have a pronounced effect on morphology, structure, stability and optical property of riboflavin gels. 相似文献
45.
A library of novel, lipid-modified derivatives of ascorbic acid was shown to exhibit highly attractive properties as surfactants, emulsifiers, oil soluble antioxidants, and highly effective gelators in organic solvents and especially water. In these systems, intermolecular hydrogen bonding and van der Waals forces act synergistically to induce gelation as confirmed by spectroscopic studies. The morphology of the formed gel has been characterized by scanning electron microscopy. 相似文献
46.
A simple Hg(2+) sensor has been developed using the vitamin B2 (riboflavin) stabilized Ag nanoparticle via a "turn off"-"turn on" mechanism; both the colour and photoluminescence properties of the riboflavin solution are used as sensitizing tools showing a sensitivity up to 5 nM Hg(2+) concentration. 相似文献
47.
The reduction of chloroauric acid using aniline adsorbed on DNA produces highly branched dendritic gold nanoparticles with concomitant formation of polyaniline (PANI) in contrast to the formation of spherical Au nanoparticles in the absence of DNA. The conformation of DNA remains intact in the process as evident from circular dichroism (CD) spectra. The UV-Vis spectrum exhibits a broad absorption peak at 520-900 nm, for a combined effect of the gold surface plasmon and π band to localized polaron band transition of DNA-doped PANI. Both the dendritic Au-PANI-DNA and the spherical Au-PANI systems emit two peaks for excitation with radiation of 300 nm and the intensity ratio of the emission and FRET peak is higher in the dendritic Au-PANI than that in the spherical Au-PANI system. The dc-conductivity values of spherical Au-PANI and dendritic Au-PANI-DNA systems are 1.2×10(-10) and 1.7×10(-8) S/cm at 30°C, respectively. 相似文献
48.
Ribeiro EA Sidooski T Nandi LG Machado VG 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,81(1):745-753
2,6-Diphenyl-4-(2,4,6-triphenylpyridinium-1-yl)phenolate (1a) and 4-[(1-methyl-4(1H)-pyridinylidene)-ethylidene]-2,5-cyclohexadien-1-one (2a) were protonated in organic solvents (dichloromethane, acetonitrile, and DMSO) to form 1b and 2b, respectively. The appearance of the solvatochromic bands of 1a and 2a was studied UV-vis spectrophotometrically by deprotonation of 1b and 2b in solution in the presence of the following amines: aniline (AN), N-methylaniline (NMAN), N,N-dimethylaniline (NDAN), n-butylamine (BA), diethylamine (DEA), and triethylamine (TEA). Titrations of 1b and 2b with the amines were carried out and the binding constants were determined from the titration curves in each solvent, using a mathematical model adapted from the literature which considers the simultaneous participation of two dye: amine stoichiometries, 1:1 and 1:2. The data obtained showed the following base order for the two compounds in DMSO: BA>DEA>TEA, while aromatic amines did not cause any effect. In dichloromethane, the following base order for 1b was verified: TEA>DEA>BA?NDAN, while for 2b the order was: TEA>DEA>BA, suggesting that 1b is more acidic than 2b. The data in acetonitrile indicated for 1b and 2b the following order for the amines: DEA>TEA>BA. The diversity of the experimental data were explained based on a model that considers the level of interaction of the protonated dyes with the amines to be dependent on three aspects: (a) the basicity of the amine, which varies according to their molecular structure and the solvent in which it is dissolved, (b) the molecular structure of the dye, and (c) the solvent used to study the system. 相似文献
49.
Tapan Nandi V Nanal W A Fernandes C A Desai M B Kurup K G Prasad P M R Rao S Padmanabhan 《Pramana》1995,44(1):67-76
A facility for carrying out beam-foil spectroscopic studies in the UV and visible region using the 400 kV electrostatic ion
accelerator at Tata Institute of Fundamental Research, Bombay is described. 相似文献
50.
Chiral discrimination and recognition is important in peptide biosynthesis, amino acid synthesis and drug designing. Detailed
structural information is available about the peptide synthesis in ribosome. However, no detailed study is available about
the discrimination in peptide synthesis. We study the conformational energy variation of neutral methoxy phenyl alanine molecule
as a function of its different dihedral angle to locate the minimum energy conformation using quantum chemical theory. We
compared the intermolecular energy surfaces of phenyl alanine molecule in its neutral and zwitterionic state using quantum
chemical theory as a function of distance and mutual orientation. The energy surfaces are studied with rigid geometry by varying
the distance and orientation. The potential energy surfaces of L-L and D-L pairs are found to be dissimilar and reflect the underlying chirality of the homochiral pair and racemic nature of the heterochiral
pair. The intermolecular energy surface of homochiral pair is more favourable than the corresponding energy surface of heterochiral
pair. 相似文献