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41.
A tight-binding representation of the kicked Harper model is used to obtain an integrable semiclassical Hamiltonian consisting of "quantized" bands of orbits. New bands appear when renormalized Harper parameters exceed integer multiples of pi/2. Orbits with frequencies commensurate with the kicking frequency are shown to correlate with classical accelerator modes in the original kicked problem. Signatures of this superdiffusive and, in our view, resonant transport are seen in both classical and quantum behavior. An important feature of our analysis is the emergence of a natural scaling relating classical and quantum couplings which is necessary for establishing correspondence. 相似文献
42.
The interaction of 1-anilinonaphthalene-8-sulphonate (ANS) with cross-linked poly(N-vinyl-2-pyrrolidone) (CPVP) was studied
by the adsorption technique at different temperatures and at two different pH values. Analysis by the Scatchard method and
the study made in the presence of urea showed that the iceberg structure of water affects the sorption of ANS to CPVP, leading
to cooperativity. The observed Giles sorption isotherms at both the pH values were of theL-type which indicated the interaction of ANS in flat configuration with the binding site in CPVP. The sorption of ANS to CPVP
was enhanced considerably at acidic pH due to some structural factors which also resulted in multilayer sorption at this pH.
Comparison of binding of ANS to CPVP and to linear poly(N-vinyl-2-pyrrolidone) demonstrated the greater contribution of hydrophobic
interaction in CPVP than in the linear polymer. 相似文献
43.
This paper deals with the propagation of solitons in real fibres, governed by the system of inhomogeneous nonlinear Schrödinger (INLS) equations. The Painlevé singularity structure analysis is utilized to check for the integrability of the system and from the analysis, the system is found to admit soliton-type lossless wave propagation. The system is transformed to its homogeneous counterpart using a suitable variable transformation and the soliton solutions are obtained through Bäcklund transformation after constructing the explicit Lax pair for the system. The one-soliton solutions are plotted for different choices of inhomogeneity parameters and the evolutionary characteristics of the solutions are analyzed. 相似文献
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46.
Bhim Bali Prasad Khushaboo Tiwari Meenakshi Singh Piyush S. Sharma Amit K. Patel Shrinkhala Srivastava 《Chromatographia》2009,69(9-10):949-957
A combination approach in solid-phase microextraction, based on a molecularly imprinted polymer-brush coating on an optical fiber coupled with a complementary molecularly imprinted polymer sensor, has been adopted for isolation, preconcentration, and analysis of dopamine at ultratrace levels in highly dilute aqueous samples. This combination enabled enhanced (up to 8.5-fold) preconcentration of the analyte, which is appropriate for achieving a stringent detection limit in clinical diagnosis of several neurodegenerative diseases. The detection limit of dopamine in biological samples was 0.018 ng mL?1 with a relative standard deviation less than 2.1% and without any non-specific contributions. 相似文献
47.
48.
Mei‐Hsin Chiu Annamalai Senthil Kumar Sundaram Sornambikai Jyh‐Myng Zen Ying Shih 《Electroanalysis》2010,22(20):2421-2427
A screen‐printed silver strip with a built‐in three‐in‐one electrode (SPAgE) configuration of Ag‐working, Ag‐counter and Ag/AgxO (silver oxides) pseudoreference electrodes has been developed for sensitive and selective electrochemical flow injection analysis (FIA) of aluminum chlorohydrate (ACH) present in antiperspirants, through the free Cl? ion liberated from ACH in aqueous medium, as a redox signal at Ag‐working electrode in pH 6 phosphate buffer solution (PBS). The solution phase and instrumental parameters were systematically optimized. The calibration graph was linear in the window 1–200 ppm concentration of ACH and the lowest detection limit (S/N=3) was 295 ppb with a slope of 0.0989 μA/ppm and regression coefficient of 0.998. Calculated relative standard deviation (RSD) values for the detection of 5 and 50 ppm ACH by this method are 2.21 % and 2.16 %, respectively. Four different antiperspirant deodorants real samples with and without ACH content were successfully analyzed and the detected values obtained were found to be in good agreement with the product labeled values. 相似文献
49.
Vinod Chhokar Meenakshi Sangwan Vikas Beniwal Kiran Nehra Kaur S. Nehra 《Applied biochemistry and biotechnology》2010,160(8):2256-2264
Tannase from Aspergillus awamori MTCC 9299 was purified using ammonium sulfate precipitation followed by ion-exchange chromatography. A purification fold
of 19.5 with 13.5% yield was obtained. Temperature of 30 °C and pH of 5.5 were found optimum for tannase activity. The effects
of metals and organic solvents on the activity of tannase were also studied. Metal ions Mg+2, Mn+2, Ca+2, Na+, and K
+
stimulated the tannase activity, while Cu+2, Fe+3, and Co+2 acted as inhibitors of the enzyme. The addition of organic solvents like acetic acid, isoamylalcohol, chloroform, isopropyl
alcohol, and ethanol completely inhibited the enzyme activity. However, butanol and benzene increased the enzyme activity. 相似文献
50.
Soumya S. Sarangi Wei Zhao Dr. Florian Müller‐Plathe Prof. Dr. Sundaram Balasubramanian Prof. 《Chemphyschem》2010,11(9):2001-2010
The complex dynamics of a room‐temperature ionic liquid, 1‐n‐butyl‐3‐methylimidazolium hexafluorophosphate ([bmim][PF6]), is studied using equilibrium classical molecular dynamics simulations in the temperature range of 250–450 K. The activation energies for the self‐diffusion of ions are around 30–34 kJ mol?1, with that of the anion a little higher than that for the cation. The electrical conductivity of the liquid is calculated and good agreement with experiments is obtained. Structural relaxation is studied through the decay of coherent (total density–density correlation) and incoherent (self part of density–density correlation) intermediate scattering functions over a range of temperatures and wave vectors relevant to the system. The relaxation data are used to identify and characterize two processes, α and β. The dependence of the two relaxation times on temperature and wave vector is obtained. The dynamical heterogeneity of the ions determined through the non‐Gaussian parameter indicates the motion of the cation to be more heterogeneous than that of the anion. The faster ones among the cations are coordinated to faster anions, while slower cations are surrounded predominantly by slower anions. Thus, the dynamical heterogeneity in this ionic liquid is shown to have structural signatures. 相似文献