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61.
62.
Compounds of a new smectogenic homologous series of α-methyl-cinnamates were prepared by condensing different 4-n-alkoxybenzoyl chloride with methoxyethyltrans-4-hydroxy-α-methylcinnamate. In this series, the first six members are non-mesogenic.n-Heptyloxy derivative exhibits monotropic smectic A phase whereas rest of the members exhibit enantiotropic smectic A mesophase.
The compounds are characterized by combination of elemental analysis and spectroscopic techniques. Enthalpies of few homologues
are measured by DSC techniques. Fluorescent properties are also observed. The thermal stabilities of the present series are
compared with those of other structurally related mesogenic homologous series. 相似文献
63.
A simple, selective, rapid, precise and accurate reverse phase high pressure liquid chromatographic method has been developed for the simultaneous estimation of diclofenac sodium and rabeprazole sodium from pharmaceutical formulations. The method was developed using a HiQ SiL C18 (250 mm × 4.6 mm i.d.) column with a mobile phase consisting of methanol:water, (80:20 v/v), at a flow rate of 1.25 mL min−1. Detection was carried out at 284 nm. Indapamide was used as an internal standard. The developed method was validated for linearity, accuracy, precision, limit of detection and limit of quantitation. The proposed method can be used for the estimation of these drugs in combined dosage forms.
相似文献64.
Pradeep K Pandey Neerja Kaushik Kamalendra Singh Bechan Sharma Alok K Upadhyay Suriender Kumar Dylan Harris Virendra N Pandey 《BMC biochemistry》2002,3(1):18-14
Background
HIV-1 RT is a heterodimeric enzyme, comprising of the p66 and p51 subunits. Earlier, we have shown that the β7-β8 loop of p51 is a key structural element for RT dimerization (Pandey et al., Biochemistry 40: 9505, 2001). Deletion or alanine substitution of four amino acid residues of this loop in the p51 subunit severely impaired DNA binding and catalytic activities of the enzyme. To further examine the role of this loop in HIV-1 RT, we have increased its size such that the six amino acids loop sequences are repeated in tandem and examined its impact on the dimerization process and catalytic function of the enzyme. 相似文献65.
Hirakawa K Yoshida M Nagatsu A Mizukami H Rana V Rawat MS Oikawa S Kawanishi S 《Photochemistry and photobiology》2005,81(2):314-319
Photosensitized DNA damage participates in solar-UV carcinogenesis, photogenotoxicity and phototoxicity. A chemoprevention of photosensitized DNA damage is one of the most important methods for the above phototoxic effects. In this study, the chemopreventive action of xanthone (XAN) derivatives (bellidifolin [BEL], gentiacaulein [GEN], norswertianin [NOR] and swerchirin [SWE]) on DNA damage photosensitized by riboflavin was demonstrated using [32P]-5'-end-labeled DNA fragments obtained from genes relevant to human cancer. GEN and NOR effectively inhibited the formation of piperidine-labile products at consecutive G residues by photoexcited riboflavin, whereas BEL and SWE did not show significant inhibition of DNA damage. The four XAN derivatives decrease the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo), an oxidative product of G, by photoexcited riboflavin. The preventive action for the 8-oxodGuo formation of these XAN derivatives increased in the following order: GEN>NOR>BEL>SWE. A fluorescence spectroscopic study and ab initio molecular orbital calculations suggested that the prevention of DNA photodamage is because of the quenching of the triplet excited state of riboflavin by XAN derivatives through electron transfer. This chemoprevention is based on neither antioxidation nor a physical sunscreen effect; rather, it is based on the quenching of a photosensitizer. In conclusion, XAN derivatives, especially GEN, may act as novel chemopreventive agents by the quenching mechanism of an excited photosensitizer. 相似文献
66.
Haresh S. Kalasariya Nikunj B. Patel Akanksha Yadav Kahkashan Perveen Virendra Kumar Yadav Faris M. Munshi Krishna Kumar Yadav Shamshad Alam You-Kyung Jung Byong-Hun Jeon 《Molecules (Basel, Switzerland)》2021,26(24)
Cosmetic industries are highly committed to finding natural sources of functional active constituents preferable to safer materials to meet consumers’ demands. Marine macroalgae have diversified bioactive constituents and possess potential benefits in beauty care products. Hence, the present study was carried out to characterize the biochemical profile of marine macroalga Chaetomorpha crassa by using different techniques for revealing its cosmetic potentials. In results, the FTIR study characterized the presence of different bioactive functional groups that are responsible for many skin-beneficial compounds whereas six and fifteen different important phycocompounds were found in GCMS analysis of ethanolic and methanolic extracts, respectively. In the saccharide profile of C. crassa, a total of eight different carbohydrate derivatives were determined by the HRLCMS Q-TOF technique, which showed wide varieties of cosmetic interest. In ICP AES analysis, Si was found to be highest whereas Cu was found to be lowest among other elements. A total of twenty-one amino acids were measured by the HRLCMS-QTOF technique, which revealed the highest amount of the amino acid, Aspartic acid (1207.45 nmol/mL) and tyrosine (106.77 nmol/mL) was found to be the lowest in amount among other amino acids. Their cosmetic potentials have been studied based on previous research studies. The incorporation of seaweed-based bioactive components in cosmetics has been extensively growing due to its skin health-promoting effects. 相似文献
67.
Superconducting State Parameters of CucZr100-c Binary Amorphous Alloys by Pseudopotential Approach 下载免费PDF全文
Aditya M. Vora 《中国物理快报》2007,24(9):2624-2627
We present the screening dependence theoretical investigations of the superconducting state parameters, i.e. electron-phonon coupling strength A, Coulomb pseudopotential μ*, transition temperature To, isotope effect exponent α, and effective interaction strength NoV of some CucZr100-c (C = 25, 30, 33, 35, 40, 45, 50, 55, 57, 60 at.%) binary amorphous alloys by employing the well-known empty core model potential of Ashcroft. Five screening functions proposed by Hartree, Taylor, Ichimaru-Utsumi, Farid et al. and Sarkar et al. are used to study the screening influence on the aforesaid superconducting properties. The transition temperature Tc obtained from the Ichimaru-Utsumi screening function is found to be in excellent agreement with available theoretical or experimental data. Also, the present results are found in qualitative agreement with the other earlier reported data, which confirms the superconducting phase in the amorphous alloys. 相似文献
68.
Ravindra P. Singh Sanjoy Roychowdhury Virendra K. Jaiswal 《Optics Communications》2007,274(2):281-285
Before we use an optical vortex for any application, it is important to know if the vortex is axial or non-axial, since properties of one type of the vortex are quite different from another. We show that the Wigner distribution can provide a solution, being different for axial and non-axial vortex. We use transport properties of the Wigner function to study the propagation of an axial as well as non-axial vortex and find them different. 相似文献
69.
Aditya M. Vora 《Central European Journal of Physics》2008,6(2):263-276
The theoretical computation of the superconducting state parameters (SSP) viz; electron-phonon coupling strength λ, Coulomb pseudopotential μ
*, transition temperature T
c
, isotope effect exponent α and effective interaction strength N
O
V of some monovalent (Cu and Au), divalent (Ca, Sr, Ba, αHg, βHg and Ra) and polyvalent (Lu, Rh, Sc, Y, La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Ac, Th, Hf, Ru, Os, Ir, V, Ta, Pa, Cr, Mo,
U, Re, Np and Pu) amorphous metals based on the different groups of the periodic table have been carried out for the first
time using the well known Ashcroft’s empty core (EMC) model pseudopotential. Herein, we have employed five different types
of local field correction functions proposed by Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) to study the exchange and correlation effects on the present investigations. A very strong influence of all the exchange
and correlation functions have been observed in the present study. Our results are in fair agreement with documented theoretical
as well as experimental data. A strong dependency of the SSP of amorphous metals on the valency Z was found.
相似文献
70.
Methylxanthine drugs are chitinase inhibitors: investigation of inhibition and binding modes 总被引:5,自引:0,他引:5
Family 18 chitinases play key roles in a range of pathogenic organisms and are overexpressed in the asthmatic lung. By screening a library of marketed drug molecules, we have identified methylxanthine derivatives as possible inhibitor leads. These derivatives, theophylline, caffeine, and pentoxifylline, are used therapeutically as antiinflammatory agents, with pleiotropic mechanisms of action. Here it is shown that they are also competitive inhibitors against a fungal family 18 chitinase, with pentoxifylline being the most potent (K(i) of 37 microM). Crystallographic analysis of chitinase-inhibitor complexes revealed specific interactions with the active site, mimicking the reaction intermediate analog, allosamidin. Mutagenesis identified the key active site residues, conserved in mammalian chitinases, which contribute to inhibitor affinity. Enzyme assays also revealed that these methylxanthines are active against human chitinases. 相似文献