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101.
Polarized Raman spectra of mixed-valent Sm0.75Y0.25S are presented and compared with those of semiconducting SmS and superconducting YS and TiN. The spectra are explained in terms of cluster deformabilities which also govern the phonon anomalies. The existence of a breathing Γ1+ deformability of Sm in Sm1?xYxS, of S in YS, of N in TiN and a quadrupolar Γ12+ deformability of N in TiN is demonstrated. The relationship between these results and the microscopic theory is discussed. 相似文献
102.
T. Chattopadhyay C. Carlone A. Jayaraman H.G.v. Schnering 《Journal of Physics and Chemistry of Solids》1982,43(3):277-284
The Raman spectrum of crystalline As4S3 has been investigated as a function of temperature from 4 to 430 K at ambient pressure, and as a function of pressure to 70 kbar at ambient temperature. The external mode frequencies which appear clearly separated from the internal modes exhibit stronger pressure and temperature sensitivity compared to the latter modes. At the β-As4S3 to α-As4S3 phase transition near 410 K, the external modes change discontinuously indicating a first-order phase transition. The internal mode frequencies remain practically unaffected. The and data are analyzed using well established approaches. Application of non-hydrostatic pressure (>60 kbar) appears to destroy the crystallinity of As4S3. 相似文献
103.
We use lattice Monte Carlo simulations to study the thermodynamics of hybridization of single-stranded "target" genes in solution with complementary "probe" DNA molecules immobilized on a microarray surface. The target molecules in our system contain 48 segments and the probes tethered on a hard surface contain 8-24 segments. The segments on the probe and target are distinct, with each segment representing a sequence of nucleotides that interacts exclusively with its unique complementary target segment with a single hybridization energy; all other interactions are zero. We examine how surface density (number of probes per unit surface area) and concentration of target molecules affect the extent of hybridization. For short probe lengths, as the surface density increases, the probability of binding long stretches of target segments increases at low surface density, reaches a maximum at an intermediate surface density, and then decreases at high surface density. Furthermore, as the surface density increases, the target is less likely to bind completely to one probe; instead, it binds simultaneously to multiple probes. At short probe lengths, as the target concentration increases, the fraction of targets binding completely to the probes (specificity) decreases. At long probe lengths, varying the target concentration does not affect the specificity. At all target concentrations as the probe length increases, the fraction of target molecules bound to the probes by at least one segment (sensitivity) increases while the fraction of target molecules completely bound to the probes (specificity) decreases. This work provides general guidelines to maximizing microarray sensitivity and specificity. Our results suggest that the sensitivity and specificity can be maximized by using probes 130-180 nucleotides long at a surface density in the range of 7 x 10(-5)- 3 x 10(-4) probe molecules per nm(2). 相似文献
104.
Selvaraj Jayaraman Nalini Devarajan Ponnulakshmi Rajagopal Shyamaladevi Babu Senthil Kumar Ganesan Vishnu Priya Veeraraghavan Chella Perumal Palanisamy Bo Cui Vijayalakshmi Periyasamy Kirubhanand Chandrasekar 《Molecules (Basel, Switzerland)》2021,26(7)
β-sitosterol (SIT), the most abundant bioactive component of vegetable oil and other plants, is a highly potent antidiabetic drug. Our previous studies show that SIT controls hyperglycemia and insulin resistance by activating insulin receptor and glucose transporter 4 (GLUT-4) in the adipocytes of obesity induced type 2 diabetic rats. The current research was undertaken to investigate if SIT could also exert its antidiabetic effects by circumventing adipocyte induced inflammation, a key driving factor for insulin resistance in obese individuals. Effective dose of SIT (20 mg/kg b.wt) was administered orally for 30 days to high fat diet and sucrose induced type-2 diabetic rats. Metformin, the conventionally used antidiabetic drug was used as a positive control. Interestingly, SIT treatment restores the elevated serum levels of proinflammatory cytokines including leptin, resistin, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) to normalcy and increases anti-inflammatory adipocytokines including adiponectin in type 2 diabetic rats. Furthermore, SIT decreases sterol regulatory element binding protein-1c (SREBP-1c) and enhances Peroxisome Proliferator–activated receptor-γ (PPAR-γ) gene expression in adipocytes of diabetic rats. The gene and protein expression of c-Jun-N-terminal kinase-1 (JNK1), inhibitor of nuclear factor kappa-B kinase subunit beta (IKKβ) and nuclear factor kappa B (NF-κB) were also significantly attenuated in SIT treated groups. More importantly, SIT acts very effectively as metformin to circumvent inflammation and insulin resistance in diabetic rats. Our results clearly show that SIT inhibits obesity induced insulin resistance by ameliorating the inflammatory events in the adipose tissue through the downregulation of IKKβ/NF-κB and c-Jun-N-terminal kinase (JNK) signaling pathway. 相似文献
105.
In this work, we have improved the order of the double-step Newton method from four to five using the same number of evaluation of two functions and two first order Fréchet derivatives for each iteration. The multi-step version requires one more function evaluation for each step. The multi-step version converges with order 3r+5, r≥1. Numerical experiments are done comparing the new methods with some existing methods. Our methods are also tested on Chandrasekhar’s problem and the 2-D Bratu problem to illustrate the applications. 相似文献
106.
Gueorguieva L Palani S Rinas U Jayaraman G Seidel-Morgenstern A 《Journal of chromatography. A》2011,1218(37):6402-6411
In the first part of this work adsorption isotherm parameters were acquired to describe the migration of recombinant streptokinase in Butyl Sepharose columns at different salt concentrations. Based on these results, a simulated moving bed (SMB) chromatographic process was designed and realised, which exploits a two-step salt gradient and allows the continuous separation of streptokinase from contaminants present in a clarified Escherichia coli cell lysate solution. This second part describes the design of the three-zone open-loop gradient SMB process applying both equilibrium theory and an equilibrium stage model and presents results of a series of experiments aiming to obtain pure streptokinase. Moreover, the potential of the SMB process and the design approach are evaluated. 相似文献
107.
Palani S Gueorguieva L Rinas U Seidel-Morgenstern A Jayaraman G 《Journal of chromatography. A》2011,1218(37):6396-6401
The design of gradient simulated moving bed (SMB) chromatographic processes requires an appropriate selection of the chromatographic system followed by the determination of adsorption isotherm parameters in the relevant range of mobile phase conditions. The determination of these parameters can be quite difficult for recombinant target proteins present in complex protein mixtures. The first part of this work includes the estimation of adsorption isotherm parameters for streptokinase and a lumped impurity fraction present in an Escherichia coli cell lysate for a hydrophobic interaction chromatography (HIC) matrix. Perturbation experiments were carried out using a Butyl Sepharose matrix with purified recombinant protein on buffer equilibrated columns as well as with crude cell lysate saturated columns. The Henry constants estimated for streptokinase were found to exhibit in a wide range a linear dependence on the salt concentration in the mobile phase. These parameters were applied in subsequent investigations to design a simulated moving bed (SMB) process capable to purify in a continuous manner recombinant streptokinase from the E. coli cell lysate. 相似文献
108.
Jayabharathi J Thanikachalam V Saravanan K Venkatesh Perumal M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1240-1246
Bioactive imidazole derivatives were synthesized and characterized by NMR spectra, mass and CHN analysis. An excited state intramolecular proton transfer (ESIPT) process in hydroxy imidazole has been studied using emission spectroscopy. In hydrocarbon solvent, the tautomer emission predominates over the normal emission and in alcoholic solvent like ethanol; a dramatic enhancement of normal emission is observed which was due to increased solvation. DFT calculation on energy, charge distribution of the rotamers in the ground and excited states of the imidazole derivative were performed and discussed. PES calculation indicates that the energy barrier for the interconversion of two rotamers is too high in the excited state than in the ground state. The interaction between bioactive imidazole derivative and bovine serum albumin (BSA) was investigated. 相似文献
109.
Jayabharathi J Thanikachalam V Padmavathy M Srinivasan N 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,81(1):380-389
(1)H and (13)C NMR spectra were recorded for some novel picrate derivatives derived from some 3,3-methyl-2,6-diarylpiperidin-4-ones and 3-benzyl-2,6-diarylpiperidin-4-one. The difference in the chemical shift of equatorial methylene proton and axial methylene proton at C(5) [Δ = δ(eq)-δ(ax)] is highly negative which is in contrast to the value observed in the corresponding parent piperidin-4-ones and this is attributed to the syn 1,3-diaxial interaction between the axial N-H bond and axial hydrogen at C-5. The effect of protonation on the chemical shifts was studied in detail. The chemical shifts of the heterocyclic ring protons are influenced by the picrate anion. Solvatochromism of picrates were studied in detail. DFT calculations were carried out in order to find out the NBO analysis, HOMO-LUMO energies, MEP studies and hyperpolarisability behaviour. The electric dipole moment (μ) and the first-hyperpolarisability (β) value of the investigated molecules have been studied theoretically which reveal that the synthesized molecules have microscopic non-linear optical (NLO) behaviour with non-zero values. 相似文献
110.
Jayabharathi J Thanikachalam V Padmavathy M Perumal MV 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,81(1):363-371
Some novel N-nitroso oxime derivatives were synthesized and characterized by (1)H, (13)C, (1)H-(1)H and (1)H-(13)C COSY NMR spectra. The spectra of all these N-nitroso oximes reveal the presence of two isomers labelled as E (-NOH group is anti to N-N=O moiety) and Z (-NOH group is syn to N-N=O moiety) in solution and the coupling constants ruled out the possibility of normal chair conformation. From the theoretical studies and coupling constant values it was found that both E (major) and Z (minor) isomers of N-nitroso oximes exist as an equilibrium mixture of CA and boat conformation (B(1)) and this was also supported by DFT calculation. The photophysical properties of these oxime derivatives were studied and the observed lower fluorescence quantum yield may be due to an increase in the non-radiative deactivation rate constant. This is attributed due to the presence of non-chair conformation of N-nitroso oxime derivatives. 相似文献