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51.
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Najeeb Ur Rehman Hidayat Hussain Samia Ahmed Al‐Riyami René Csuk Mohammed Khiat Ghulam Abbas Ahmed Al‐Rawahi Ivan R. Green Ishtiaq Ahmed Ahmed Al‐Harrasi 《Helvetica chimica acta》2016,99(8):632-635
One new diacylglycoside named lyciumaside ( 1 ) and a new sesquiterpene lactone named lyciumate ( 2 ) were isolated from Lycium shawii Roem . & Schult . The structures of the two new compounds were elucidated based on 1D‐ (1H‐ and 13C‐NMR and NOE) and 2D‐NMR (COSY, HSQC, and HMBC) spectroscopic techniques, and mass spectrometry (ESI‐MS). Preliminary evaluations demonstrated lyciumaside ( 1 ) possesses strong antioxidant activity with an IC50 = 30 μg/ml (80% inhibition) while it was inactive in α‐glucosidase and urease enzymes assays. 相似文献
53.
D. Bucurescu Gh. Căta-Danil I. Căta-Danil M. Ivaşcu N. Mărginean C. Rusu L. Stroe C.A. Ur A. Gizon J. Gizon B. Nyakó J. Timár L. Zolnai A.J. Boston D.T. Joss E.S. Paul A.T. Semple C.M. Parry 《The European Physical Journal A - Hadrons and Nuclei》2001,10(3):255-258
High-spin states in the 96Tc nucleus have been studied with the reactions 82Se(19F,5nγ) at 68 MeV and Zn(36S,αpxn) at 130 MeV. Two γ-ray cascades (irregular bandlike structures) have been observed up to an excitation energy of about 10
MeV and spin 21-22?.
Received: 19 January 2001 / Accepted: 30 March 2001 相似文献
54.
Hafiz T.Ali MRamzan M Imran Arshad Nicola A.Morley M.Hassan Abbas Mohammad Yusuf Atta Ur Rehman Khalid Mahmood Adnan Ali Nasir Amin MAjaz-un-Nabi 《中国物理 B》2022,31(2):27502-027502
We investigate the impact of Ni insertion on the structural,optical,and magnetic properties of Ba0.8La0.2Fe12-xNixO19hexaferrites(Ni substituted La-BaM hexaferrites).Samples were prepared using the conventional co-precipitation method and sintered at 1000℃for 4 hours to assist the crystallization process.An analysis of the structure of the samples was carried out using an x-ray diffraction(XRD)spectrometer.The M-type hexagonal structure of all the samples was confirmed using XRD spectra.The lattice parameters a and c were found to be in the ranges of 5.8925±0.001 nm–5.8952±0.001 nm and 23.2123±0.001 nm–23.2219±0.001 nm,respectively.The M-type hexagonal nature of the prepared samples was also indicated by the presence of corresponding FT-IR bands and Raman modes in the FT-IR and Raman spectra,respectively.EDX results confirmed the successful synthesis of the samples according to the required stoichiometric ratio.A UV-vis spectrometer was used to record the absorption spectra of the prepared samples in the wavelength range of 200 nm–1100 nm.The optical energy bandgap of the samples was found to be in the range of 1.21 eV–3.39 eV.The M–H loops of the samples were measured at room temperature at an applied magnetic field range of 0 kOe–60 kOe.A high saturation magnetization of 99.92 emu/g was recorded in the sample with x=0 at a microwave operating frequency of 22.2 GHz.This high value of saturation magnetization is due to the substitution of La3+ions at the spin-up(12k,2a,and 2b)sites.The Ni substitution is proven to be a potential candidate for the tuning of the optical and magnetic parameters of M-type hexaferrites.Therefore,we suggest that the prepared samples are suitable for use in magneto-optic applications. 相似文献
55.
Jun Ruan Wenbo Zhang Hang Zhang Yun Chen Fawad Ur Rehman Hui Jiang Steffen Strehle Alberto Pasquarelli Xuemei Wang 《中国化学快报》2018,29(6):919-921
The new boron-doped nanocrystalline diamond microelectrode arrays (BNCD-MEAs) with 16 channels were designed to detect biological signals from some activated cancer cells. Upon recordings of the released H2O2 from cancer cells stimulated by ascorbic acid (AA), it can readily detect the reactive oxygen species (ROS) released from target cells, which will be helpful for the cancer cell recognition and also beneficial for further studying the cause of relevant disease. 相似文献
56.
Boris Orel Robi Ješe Aljaž Vilčnik Urška LavrenčIč Štangar 《Journal of Sol-Gel Science and Technology》2005,34(3):251-265
The aim of this study was, at first, to re-consider the IR spectra of methyltriethoxysilane (MTEOS) catalysed with HCl (hydrolysis) and to compare them with IR spectra of MTEOS catalysed with trifluoroacetic acid (TFAcOH). TFAcOH as a strong carboxylic acid performs non-hydrolytic sol-gel process based on the condensation between the alkoxide and the acid function, liberating ester molecules (solvolysis). We assessed from the time-dependent IR attenuated reflection spectroscopic (IR ATR) measurements the solvolysis and hydrolysis reactions, formation of the oligomeric species and final condensation products. Additional evidence for the formation of these species was obtained from the spectra of films dip-coated from sols aged to different extent. The results of the IR spectral analysis showed that the structure of both xerogels consisted of irregular Tn (n = 8, 10, 12) cube-like species bridged via the ladder-like oligomers (in the case of MTEOS/TFAcOH) and open-chain trisiloxane species (for MTEOS/HCl). 29Si NMR spectra of MTEOS/TFAcOH showed only signals of T3 while MTEOS/HCl spectra showed beside T3 also T2 signals, in agreement with IR spectra results. From the XRD peaks at low Bragg angles (∼ 9–10°) we inferred that both xerogels consisted of nanocrystalline CH3-SiO3/2 species. In addition, the surface energy values of the films deposited from the corresponding sols were measured and the dispersive and polar portions correlated with the spectral features noted in the films. 相似文献
57.
N. A. Andriyanova L. A. Smirnova Yu. D. Semchikov K. V. Kir’yanov N. V. Zaborshchikova V. F. Ur’yash N. V. Vostokov 《Polymer Science Series A》2006,48(5):483-488
Cyanoethyl chitosan derivatives with various substitution degrees have been synthesized by the nucleophilic addition of acrylonitrile to the functional groups of chitosan. The process proceeds under homogeneous conditions without any catalyst at various pH values and reagent concentrations in the temperature range of 273–333 K. The formation of cyanoethyl chitosans is established by a gain in the weight of chitosan, a change in its content of nitrogen, and the appearance of an absorption band at 2250 cm?1 in the IR spectrum which corresponds to the stretching vibrations of a-C≡N group. It has been shown that the most efficient addition of acrylonitrile occurs at 273 K and pH 5.5. Cyanoethyl chitosan samples show better mechanical parameters and are characterized by a lower ordering than the parent chitosan. 相似文献
58.
Ur?ka L. ?tangar Boris Orel Neva Gro?elj Patrick Judeinstein Franco Decker Panagiotis Lianos 《Monatshefte für Chemie / Chemical Monthly》2001,18(10):103-112
A hybrid silicon precursor (ICS-PPG) obtained by reaction of 3-isocyanatopropyltriethoxy silane with poly-(propyleneglycol)-bis-(2-aminopropyl ether) was recognized as a potential host for various salts and molecular species. It has been used for electrochromic, gasochromic, photovoltaic, and fuel cell applications. This focuses on proton conducting gels (PWA/ICS-PPG, SiWA/ICS-PPG, and W-PTA/ICS-PPG) obtained after the incorporation of polyoxometalates in the ICS-PPG host. IR spectroscopic measurements are used to reveal the entrapment, the aggregation, and the interactions of W-PTA, PWA, or SiWA with the sol-gel derived network. The proton conductivity of the composites, measured using impedance spectroscopy, increases with increasing concentration of the polyoxometalates from 10−6 to 10−3 S/cm. 相似文献
59.
60.
Duan Ni Jiacheng Wei Xinheng He Ashfaq Ur Rehman Xinyi Li Yuran Qiu Jun Pu Shaoyong Lu Jian Zhang 《Chemical science》2021,12(1):464
Allostery, which is one of the most direct and efficient methods to fine-tune protein functions, has gained increasing recognition in drug discovery. However, there are several challenges associated with the identification of allosteric sites, which is the fundamental cornerstone of drug design. Previous studies on allosteric site predictions have focused on communication signals propagating from the allosteric sites to the orthosteric sites. However, recent biochemical studies have revealed that allosteric coupling is bidirectional and that orthosteric perturbations can modulate allosteric sites through reversed allosteric communication. Here, we proposed a new framework for the prediction of allosteric sites based on reversed allosteric communication using a combination of computational and experimental strategies (molecular dynamics simulations, Markov state models, and site-directed mutagenesis). The desirable performance of our approach was demonstrated by predicting the known allosteric site of the small molecule MDL-801 in nicotinamide dinucleotide (NAD+)-dependent protein lysine deacetylase sirtuin 6 (Sirt6). A potential novel cryptic allosteric site located around the L116, R119, and S120 residues within the dynamic ensemble of Sirt6 was identified. The allosteric effect of the predicted site was further quantified and validated using both computational and experimental approaches. This study proposed a state-of-the-art computational pipeline for detecting allosteric sites based on reversed allosteric communication. This method enabled the identification of a previously uncharacterized potential cryptic allosteric site on Sirt6, which provides a starting point for allosteric drug design that can aid the identification of candidate pockets in other therapeutic targets.Using reversed allosteric communication, we performed MD simulations, MSMs, and mutagenesis experiments, to discover allosteric sites. It reproduced the known allosteric site for MDL-801 on Sirt6 and uncovered a novel cryptic allosteric Pocket X. 相似文献