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371.
We propose an extension of the MSSM by adding vector like ‘matter’ fields with masses near the TeV scale. This extension allows us to generate the masses of the bottom quark and tau lepton via radiative corrections such that only up type Higgs doublet couples with quarks and leptons. In addition to providing a natural explanation of the hierarchies between mb,τ and mt, this new extension, which we call FMSSM, allows the heavy sector of the MSSM Higgs bosons to be essentially fermiophobic as well as gaugephobic. Moreover, in this scenario there is no upper bound for the parameter tanβ. FMSSM can be distinguished from the MSSM, and has peculiar and unorthodox signals at the LHC, especially for the Higgs sector. 相似文献
372.
Prasenjit Mondal Rajdeep Chowdhury Somen Nandi Md. Asif Amin Kankan Bhattacharyya Surajit Ghosh 《化学:亚洲杂志》2019,14(24):4616-4624
The dynamics of cell‐cell adhesion are complicated due to complexities in cellular interactions and intra‐membrane interactions. In the present work, we have reconstituted a liposome‐based model system to mimic the cell‐cell adhesion process. Our model liposome system consists of one fluorescein‐tagged and one TRITC (tetramethyl‐rhodamine isothiocyanate)‐tagged liposome, adhered through biotin‐neutravidin interaction. We monitored the adhesion process in liposomes using Förster Resonance Energy Transfer (FRET) between fluorescein (donor) and TRITC (acceptor). Occurrence of FRET is confirmed by the decrease in donor lifetime as well as distinct rise time of the acceptor fluorescence. Interestingly, the acceptor's emission exhibits fluctuations in the range of ≈3±1 s. This may be attributed to structural oscillations associated in two adhered liposomes arising from the flexible nature of biotin‐neutravidin interaction. We have compared the dynamics in a cell‐mimicking liposome system with that in an in vitro live cell system. In the adhered live cell system, we used CPM (7‐diethylamino‐3‐(4‐maleimido‐phenyl)‐4‐methylcoumarin, donor) and nile red (acceptor), which are known to stain the membrane of CHO (Chinese Hamster Ovary) cells. The dynamics of the adhered membranes of two live CHO cells were observed through FRET between CPM and nile red. The acceptor fluorescence intensity exhibits an oscillation in the time‐scale of ≈1±0.75 s, which is faster compared to the reconstituted liposome system, indicating the contributions and involvement of multiple dynamic protein complexes around the cell membrane. This study offers simple reconstituted model systems to understand the complex membrane dynamics using a FRET‐based physical chemistry approach. 相似文献
373.
In this work we demonstrate that a doubly hydrogen-bonded interface of two carboxylic acid groups behaves as efficient conduit to transmit the rotor effects for IVR acceleration in a phenyl ring. The phenomenon has been demonstrated by measuring the resolved emission spectra following SVL excitations in S(1) of a 1:1 mixed dimer between acetic acid and benzoic acid. The role of the methyl rotor has been ascertained by comparing the results with those obtained for an analogous dimeric system between formic acid and benzoic acid. 相似文献
374.
V. S.?Prabhudesai D.?Nandi E.?KrishnakumarEmail author 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,35(2):261-266
Low energy electron attachment to the fullerene molecule (C60) and its
temperature dependence are studied in a crossed electron beam–molecular
beam experiment. We observe the strongest relative signal of C60 anion
near 0 eV electron energy with respect to higher energy resonant peaks
confirming the contribution of s-wave capture to the electron attachment
process and hence the absence of threshold behavior or activation barrier
near zero electron energy. While we find no temperature dependence for the
cross-section near zero energy, we observe a reduction in the cross-sections
at higher electron energies as the temperature is increased, indicating a
decrease in lifetime of the resonances at higher energies with increase in
temperature. 相似文献
375.
376.
377.
Sen Gupta Kalyan Kali Maiti Surajit Samanta Tapashi Nandi Sanghamitra Banerjee Amalendu 《Transition Metal Chemistry》1982,7(5):274-279
Summary The kinetics of oxidation of ethylene glycol, 2,3-butanediol and pinacol have been studied spectrophotometrically under different experimental conditions. The reactions seem to occur through the formation of an intermediate complex between each diol and iridium(IV). The complexes decompose through intermediate free radicals to form formaldehyde, acetaldehyde and acetone, respectively. Thermodynamic parameters have been calculated. 相似文献
378.
Satyanarayan Nandi 《Nuclear Physics B》1975,97(1):178-188
Using new techniques for deriving bounds satisfying the requirements of unitarity and analiticity, optimal constraints on the scalar K?3 form factor are obtained, given the s-wave, elastic phase shift. It is assumed that the propagators of current divergences satisfy unsubtracted dispersion relations, that axial divergences are dominated by pion and kaon poles and that the chiral symmetry breaking Hamiltonian transforms as . Recent SLAC-Santa Cruz data satisfy these constraints, as does the Callan-Treiman relation. The constraint on the slope of the form factor, given either the Callan-Treiman relation or the data, is badly violated by the current algebra prediction of Dashen and Weinstein. This violation suggests the necessity for subtraction, corresponding to a chiral symmetry breaking Hamiltonian density with scale dimension greater than or equal to two. The results depend only weakly on the elastic phase shift. 相似文献
379.
Carbonylative Sonogashira annulation sequence for one pot synthesis of 4-quinolone and 4H-chromen-4-one has been developed in presence of Pd-NHC catalyst. Substituted 2-iodoaniline and 2-iodophenol independently underwent in the carbonylative Sonogashira annulation reaction with a variety of acetylenes to result in 4-quinolone and flavone derivatives respectively in good to excellent yield. Moreover, this protocol does not require toxic CO gas, high catalyst loading and any expensive salt/additive. Herein we, for the first time, are using Mo(CO)6, as solid CO source for the one pot synthesis of flavone derivatives via carbonylative Sonogashira annulation reaction. 相似文献
380.
Subhajit Chakraborty Somen Nandi Kankan Bhattacharyya Saptarshi Mukherjee 《Chemphyschem》2020,21(5):406-414
Fluorescence dynamics of gold nanoclusters (Au9 and Au25) are studied in the complex and crowded environment of a triblock co-polymer (F127) hydrogel and inside cervical cancer cell, HeLa. In the hydrogel, spherical micelles of F127 remain immobilized with a hydrophobic core (PPO) and a hydrophilic corona (PEO) region. The fluorescence anisotropy decay suggests that the timescale of rotational relaxation in the hydrogel is similar to that in bulk water (viscosity ∼1 cP). From fluorescence correlation spectroscopy (FCS) it is inferred that the local viscosity in the hydrogel is 12 cP for Au9 and 18 cP for Au23. These results indicate that gold nanoclusters (AuNCs) localize in the corona region of the hydrogel. Evidently, frictions against rotation and translation are different inside the gel. It is suggested that rotation of the AuNCs senses the immediate water-like “void” region while translation motion involves in-and-out movement of the AuNCs at the periphery of the gel. Finally, the gold nanoclusters are used for cell imaging and estimation of intracellular viscosity of HeLa cells. 相似文献