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51.
We have developed a gold-catalyzed intramolecular cyclization of variously substituted acetylenic amines under mild conditions, which yields pyrrolopyridines and 2-substituted indoles, quantitatively. The cycloisomerization of acetylenic amines was achieved with AuCl3 as catalyst without the use of base, acid or N-protecting group. 相似文献
52.
Soumya Basu Basab Chattopadhyay A. Ganguly P. Chakraborty P. Roy Chowdhury S. Samanta M. Mukherjee A. K. Mukherjee S. K. Choudhuri 《应用有机金属化学》2009,23(12):527-534
A mononuclear copper (II) complex of N‐2‐hydroxyhippuric acid (2HHA), [Cu(HA)(H2O)2], has been synthesized and characterized by spectroscopic and X‐ray powder diffraction studies. Crystal structure of [Cu(HA)(H2O)2] reveals a distorted square‐pyramidal geometry around the metal center. The crystal packing in the complex exhibits a three‐dimensional framework formed by intermolecular O? ; H···O and C? H···O hydrogen bonds. Toxicity and antitumor properties of the complex have been studied in vivo. The complex, capable of depleting glutathione (GSH) at nontoxic doses, may be utilized to sensitize drug‐resistant cells where resistance is due to an elevated level of GSH. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
53.
We present a complex multiconfigurational self‐consistent field (CMCSCF)‐based approach to investigate electron‐atom scattering resonances. It is made possible by the use of second quantization algebra adapted for biorthogonal spin orbitals, which has been applied to develop a quadratically convergent CMCSCF method. To control the convergence to the correct CMCSCF stationary point, a modified step‐length control algorithm is introduced. Convergence to a tolerance of 1.0 × 10?10 a.u. for the energy gradient is found to be typically within 10 iterations or less. A method involving the first block of the M matrix defined in the multiconfigurational spin tensor electron propagator method (MCSTEP) based on the CMCSCF reference state has been implemented to investigate 2P Be? shape resonances. The position and width of these resonances have been calculated for different complete active space choices. The wide distribution of the position and width of the resonance reported in the literature is explained by the existence of two distinct resonances which are close in energy. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
54.
Sudip Chaudhuri Biswapathik Pahari Bidisha Sengupta Pradeep K. Sengupta 《Journal of photochemistry and photobiology. B, Biology》2010,98(1):12-19
Recent years have witnessed burgeoning interest in plant flavonoids as novel therapeutic drugs targeting cellular membranes and proteins. Motivated by this scenario, we explored the binding of robinetin (3,7,3′,4′,5′-pentahydroxyflavone, a bioflavonoid with remarkable ‘two color’ intrinsic fluorescence properties), with egg yolk phosphatidylcholine (EYPC) liposomes and normal human hemoglobin (HbA), using steady state and time resolved fluorescence spectroscopy. Distinctive fluorescence signatures obtained for robinetin indicate its partitioning (Kp = 8.65 × 104) into the hydrophobic core of the membrane lipid bilayer. HbA–robinetin interaction was examined using both robinetin fluorescence and flavonoid-induced quenching of the protein tryptophan fluorescence. Specific interaction with HbA was confirmed from three lines of evidence: (a) bimolecular quenching constant Kq ? diffusion controlled limit; (b) closely matched values of Stern–Volmer quenching constant and binding constant; (c) τ0/τ = 1 (where τ0 and τ are the unquenched and quenched tryptophan fluorescence lifetimes, respectively). Absorption spectrophotometric assays reveal that robinetin inhibits EYPC membrane lipid peroxidation and HbA glycosylation with high efficiency. 相似文献
55.
Densities and viscosities of urea in (1.0, 2.5, and 5.0) mass% of aqueous glucose solutions have been measured at T = (298.15, 303.15, 308.15, and 313.15) K, respectively. Apparent molar volumes, limiting partial molar volume, and relative viscosity have been obtained from the density and viscosity data. Limiting partial molar expansibilities have also been calculated from the temperature dependence of limiting partial molar volumes. The viscosity data has been analyzed using the Jones–Dole equation. The results are used to establish the nature of solute–solute and solute–solvent interactions. The activation parameters of viscous flow have also been calculated on the basis of transition state treatment of the relative viscosity. Result shows that the solute acts as water structure breaker and posses’ weak solute–solvent interaction. 相似文献
56.
Anuva Samanta Bijan Kumar Paul Sankar Jana Nikhil Guchhait 《Photochemistry and photobiology》2010,86(5):1022-1029
The photophysical properties of 5-(4-fluorophenyl)-2-hydroxypyridine (FP2HP) at different pH and its fluorescence response toward different transition metal ions have been studied by steady-state absorption and emission spectroscopy in combination with quantum chemical calculations. Although keto-enol tautomerization is observed in the excited state, the molecule is weakly fluorescent due to the presence of electron-rich nitrogen atom and relatively electron-deficient fluorine atom, which may lead to photoinduced electron transfer process. In the presence of the transition metal ions, such as Zn2+, Cd2+, Hg2+, etc., the studied molecule exhibits changes in its absorption and emission properties. The present system shows fluorescence enhancement instead of usual quenching in presence of the transition metal ions, such as Fe2+ and Cu2+. Spectral observation leads to the interpretation that this structurally simple molecule can be effectively utilized as a chelation-enhanced fluorescence-based chemosensor for the detection of transition metal ions. The experimental findings corroborate well with theoretical calculations at Hartree–Fock level using 6-31G** and lanl2dz basis sets. 相似文献
57.
Stable, high-power, second-harmonic-generation (SHG) of a compact CW Ytterbium (Yb) fiber laser at 1064 nm into the green
and its use as a pump source for CW singly-resonant optical parametric oscillator (SRO) is demonstrated. Using a simple single-pass
SHG configuration in MgO:sPPLT, as much as 9.6 W of single-frequency green radiation at 532 nm is generated from 30 W of fundamental
power at a conversion efficiency of 32.7% in a Gaussian spatial profile with a beam quality factor of M
2 < 1.3. Thermal effects have been investigated at different fundamental power levels and various thermal management schemes
are employed to maximize the second-harmonic power. The green source is successfully deployed to pump a CW SRO tunable over
855–1408 nm, generating up to 2.1 W of idler at 1168 nm. The peak-to-peak idler power stability is better than 10.7% over
40 min, with beam quality factor M
2 < 1.26 for the idler and M
2 < 1.52 for the signal. 相似文献
58.
A simple electrochemical process has been implemented to fabricated fractal structured leaf-like metallic zinc. The fabricated material was structurally characterized using X-ray diffraction that reveals the hexagonal unit cell structure. Also the growth of the structure is anisotropic. Field emission scanning electron microscopic images revealed clearly the leaf-like morphology of the fabricated material is fern like and ∼500 μm in length, ∼50-60 μm wide and the platelets thickness is ∼5 μm. The growth of this structure is diffusion controlled and locally accomplished with the oriented attachment. Raman shift measurement revealed the existence of surface optical phonon modes which is very significant for surface defects. 相似文献
59.
Let \({\mathcal{P}}\) be an ideal of closed quotients of a completely regular frame L and \({\mathcal{R}_{\mathcal{P}}(L)}\) the collection of all functions in the ring \({\mathcal{R}(L)}\) whose support belong to \({\mathcal{P}}\) . We show that \({\mathcal{R}(L)}\) is a Noetherian ring if and only if \({\mathcal{R}(L)}\) is an Artinian ring if and only if L is a finite frame. Using this result, we next show that if \({\mathcal{P}}\) is the ideal of all compact closed quotients of L and L is \({\mathcal{P}}\) -continuous, then \({\mathcal{R}_{\mathcal{P}}(L)}\) is a Noetherian ring if and only if L is finite. Moreover, we show that L is a P-frame if and only if each ideal of \({\mathcal{R}(L)}\) is of the form \({\mathcal{R}_{\mathcal{P}}(L)}\) for some choice of \({\mathcal{P}}\) . We furnish equivalent conditions for \({\mathcal{R}_{\mathcal{P}}(L)}\) to be a prime ideal, a free ideal, and an essential ideal of \({\mathcal{R}(L)}\) separately in terms of the cozero elements of L. Finally, we show that L is basically disconnected if and only if \({\mathcal{R}(L)}\) is a coherent ring. 相似文献
60.
Sukanta Kumar DashAmar Nath Samanta Syamalendu S. Bandyopadhyay 《Fluid Phase Equilibria》2011,307(2):166-174
In this work, new experimental results of the vapour-liquid equilibrium (VLE) of CO2 in aqueous 2-amino-2-methyl-1-propanol (AMP) and piperazine (PZ) have been presented in the temperature range of 298-328 K and PZ concentration range of 2-8 mass%, keeping the total amine concentration in the solution at 30 mass%. The partial pressures of CO2 were in the range of 0.1-1450 kPa. A thermodynamic model was developed to correlate and predict the VLE of CO2 in aqueous AMP + PZ. The electrolyte nonrandom two liquid (ENRTL) theory has been used to develop the VLE model for the quaternary system (CO2 + AMP + PZ + H2O) to describe the equilibrium behaviour of the solution. The experimental data from this work and data available in the literature were used to regress the ENRTL interaction parameters. The model predictions are in good agreement with the experimental data of CO2 solubility in aqueous blends of this work as well as those reported in the literature. The current model can also predict speciation, heat of absorption, pH of the CO2 loaded solution, and amine volatility. 相似文献