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101.
We demonstrate here that the dipole-allowed optical absorption spectrum of a parabolic quantum dot subjected to an external magnetic field reflects the interelectron interaction effects when the spin-orbit (SO) interaction is also taken into account. We have investigated the energy spectra and the dipole-allowed transition energies for up to four interacting electrons parabolically confined, and have uncovered several novel effects in those spectra that are solely due to the SO interaction. 相似文献
102.
Gharah N Chakraborty S Mukherjee AK Bhattacharyya R 《Chemical communications (Cambridge, England)》2004,(22):2630-2632
A combination of the newly synthesized and structurally characterized compound, [MoO(O2)2(saloxH)](saloxH2= salicylaldoxime) as catalyst, H2O2 as terminal oxidant and NaHCO3 as co-catalyst when stirred in CH3CN (10 cm3) at room temperature (rt) shows a very pronounced efficiency epoxidation of olefinic compounds, the method being green and economical. 相似文献
103.
A laser-induced forward transfer technique has been applied for the maskless patterning of amorphous V2O5 thin films. A sheet beam of a frequency doubled (SHG) Q-switched Nd:YAG laser was irradiated on a transparent glass substrate (donor), the rear surface of which was pre-coated with a vacuum-deposited V2O5 180 nm thick film was either in direct contact with a second glass substrate (receiver) or a 0.14 mm air-gap was maintained between the donor film and the receiving substrate. Clear, regular stripe pattern of the laser-induced transferred film was obtained on the receiver. The pattern was characterized using X-ray diffraction (XRD), optical absorption spectroscopy, scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), atomic force microscopy (AFM), etc. 相似文献
104.
Midde SreekanthGavinolla Pranitha Bharatam JagadeeshTushar Kanti Chakraborty 《Tetrahedron letters》2011,52(14):1709-1712
Stereoselective construction of highly substituted five-membered carbocycles with multiple chiral centres is described. Sharpless kinetic resolution was applied as the key step to prepare the required 2,3-epoxy alcohols and a Ti(III) radical mediated opening of the epoxide ring followed by intramolecular trapping of the generated radical with a suitably placed α,β-unsaturated ester resulted in the formation of five-membered carbocycles with up to three consecutive new chiral centres stereoselectively fixed. 相似文献
105.
Construction of 6/7 fused bicycles featuring C/D rings of micrandilactone C and rubrifloradilactone B is reported through IMDA reaction of properly designed substrates. Also a route to the construction of a tricycle having A/B ring of nortriterpenoids of schisandra family is reported using RCM and a bromonium ion initiated cycloetherification reaction as the key steps. 相似文献
106.
Samrat Chatterjee Ezio Venturino Subhendu Chakraborty Joydev Chattopadhyay 《Mathematical Methods in the Applied Sciences》2009,32(13):1738-1750
We show how the inclusion of the defense strategy by different species can alter the prediction of simple models. One of the defense strategy by the phytoplankton population against their grazer is the release of toxic chemicals. In turn the zooplankton population reduces there predation rate over toxin producing phytoplankton (TPP) to protect themselves from those toxic chemicals. Thus, when the level of toxicity is high, the grazing pressure is low and when the level of toxicity is low or when the toxin is absent, the grazing pressure is high. Here we have considered a TPP–zooplankton system where the rate of toxin liberation and the predation rate vary with zooplankton abundance. We observe that our proposed model has the potential to show different dynamical behaviour that are similar to that seen in real‐world situations. Further, we consider three different functional forms for the distribution of the toxins and compare them using latin hypercube sampling technique and found that the functional forms seem to have no effect in determining the final outcome of the system. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
107.
The paper presents a generalized economic manufacturing quantity model for an unreliable production system in which the production facility may shift from an ‘in-control’ state to an ‘out-of-control’ state at any random time (when it starts producing defective items) and may ultimately break down afterwards. If a machine breakdown occurs during a production run, then corrective repair is done; otherwise, preventive repair is performed at the end of the production run to enhance the system reliability. The proposed model is formulated assuming that the time to machine breakdown, corrective and preventive repair times follow arbitrary probability distributions. However, the criteria for the existence and uniqueness of the optimal production time are derived under general breakdown and uniform repair time (corrective and preventive) distributions. The optimal production run time is determined numerically and the joint effect of process deterioration, machine breakdowns and repairs (corrective and preventive) on the optimal decisions is investigated for a numerical example. 相似文献
108.
Swagata Chakraborty Susmitha A. L. Ramakrishna V. Hosur 《Magnetic resonance in chemistry : MRC》2012,50(9):587-591
Direct detection of 13C nucleus can be used as a valuable alternative where 1H detection poses a challenge due to relaxation effects, chemical exchange and poor chemical shift dispersion. In this context, we have designed a suite of 2D 13Cα‐detected hNCA experiments that provide sequential correlations of 13Cα with 15N on one hand and efficient spectroscopic labeling of certain groups of residues, namely, Gly, Ala, Ser and Thr, on the other. These residues act as checkpoints in the sequential walk, which in turn offer new possibilities of backbone assignment of small proteins from a set of 2D experiments, thereby providing great economy in terms of spectrometer time. The direct identification of peptide segments around Gly, Ala, Ser and Thr residues along a protein chain will be highly valuable for deriving important information on sites of ligand binding, phosphorylation, inhibitor/substrate binding, understanding protein folding pathways, comprehending local conformational dynamics etc. without having to obtain complete sequence‐specific assignments, which can be time consuming and at times formidable, especially in large proteins. We have illustratively demonstrated the multifaceted applications of these variants of 2D experiments on ubiquitin and M‐crystallin. We foresee that these 2D hNCA experiments will provide economic and efficient strategies for studying the structure and function of proteins. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
109.
Chakraborty S Chaudhuri S Pahari B Taylor J Sengupta PK Sengupta B 《Journal of luminescence》2012,132(6):1522-1528
Hesperitin, a ubiquitous bioactive flavonoid abundant in citrus fruits is known to possess antioxidant, anti-carcinogenic, hypolipidemic, vasoprotective and other important therapeutic properties. Here we have explored the interactions of hesperitin with normal human hemoglobin (HbA), using steady state and time resolved fluorescence spectroscopy, far UV circular dicroism (CD) spectroscopy, combined with molecular modeling computations. Specific interaction of the flavonoid with HbA is confirmed from flavonoid-induced static quenching which is evident from steady state fluorescence as well as lifetime data. Both temperature dependent fluorescence measurements and molecular docking studies reveal that apart from hydrogen bonding and van der Waals interactions, electrostatic interactions also play crucial role in hesperitin-HbA interactions. Furthermore, electrostatic surface potential calculations indicate that the hesperitin binding site in HbA is intensely positive due to the presence of several lysine and histidine residues. 相似文献
110.