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91.
Anish Khan Aftab Aslam Parwaz Khan Abdullah M. Asiri Malik Abdul Rub Naved Azum Mohammed M. Rahman Sher Bahadar Khan Sulaiman Ab Ghani 《Applied biochemistry and biotechnology》2013,169(6):1927-1939
Technology always has been an indispensible part in the development of biosensors. The performance of biosensors is being tremendously improved using new materials as transducer as well as binding material in their construction. The use of new materials allowed innovation on transduction technology in biosensor preparations. Because of the submicron dimensions of these sensors, simple and rapid analyses in vitro as well as in vivo are now possible. Portable instruments capable of analysing multiple components are becoming available, too. Sensors that provide excellent temporal and spatial resolution for in vivo monitoring such as for measurement of neurotransmitters have become prominent. The interest to improve the stability, sensitivity and selectivity of the sensors is paramount. This study tries to give an overview of the present status of the material-based biosensor design and new generation of choline/acetylcholine neurotransmitter biosensors. 相似文献
92.
Ayaz Mohd Aftab Aslam Parwaz Khan Shaista Bano K.S. Siddiqi 《Arabian Journal of Chemistry》2013,6(4):369-378
The development of UV and fluorescence spectrophotometric methods for the quantitative determination of alprazolam in dosage forms using As(III)?SDS system. The two simple and sensitive, spectrophotometric and spectrofluorimetric methods were developed for the determination of alprazolam (ALP) in tablets. These methods are based on formation of ALP?As(III) complex in the presence of SDS. The UV-spectrum of 30% methanolic solution of ALP (5 × 10?5 M) at pH 6.5 (Mclivaine buffer) was run between 200 and 380 nm. The absorption spectrum of ALP exhibits two peaks with a λmax. at 255 nm and a weak band at 325 nm. When the spectra of the drug were run at varying pH in the region 200–380 nm, one isosbestic point at 290 nm was observed, which indicated the presence of two ionic conditions in solution. The complex exhibited an absorption maximum at 265 nm and emission peak at 520 nm with respect to the excitation wavelength of 325 nm. The spectrophotometric method was found to be linear in 8.0–17.0 μg ml?1 range with detection limit of 13.520 μg ml?1, while 0.05–9.5 μg ml?1 range was with detection limit of 1.048 × 10?2 μg ml?1 by spectrofluorimetric method. The mean percentage recovery of the added quantity was found to be 99.54 (spectrophotometric method) and 100.22 (spectrofluorimetric method) and the %RSD are lower than 0.478 and 0.296 determined spectrophotomerically and spectrofluorimtrically, respectively. This indicates that the proposed method is accurate. The apparent ionization constant of ALP was found to be 9.29. The spectra, experimental conditions were set followed by determination stoichiometry, stability constant and thermodynamic parameters of the As(III), Co(II), Ni(II), and Zn(II) complexes with ALP at pH 6.5. The proposed methods have been successfully applied to the assay of ALP in tablets and the results were statistically evaluated. 相似文献
93.
Mohammed M. Rahman Aslam Jamal Sher Bahadar Khan Mohd Faisal 《Journal of nanoparticle research》2011,13(9):3789-3799
The production of low-dimensional nanoparticles (NPs) with appropriate surface modification has attracted increasing attention
in biological, biochemical, and environmental applications including chemical sensing, photocatalytic degradation, separation,
and purification of toxic molecules from the matrices. In this study, iron oxide NPs have been prepared by hydrothermal method
using ferric chloride and urea in aqueous medium under alkaline condition (pH 9 ~ 10). As-grown low-dimensional NPs have been
characterized by UV–vis spectroscopy, FT-IR, X-ray diffraction, Field emission scanning electron microscopy, Raman spectroscopy,
High-resolution Transmission electron microscopy, and Electron Diffraction System. The uniformity of the NPs size was measured
by the scanning electron microscopy, while the single phase of the nanocrystalline β-Fe2O3 was characterized using powder X-ray diffraction technique. As-grown NPs were extensively applied for the photocatalytic
degradation of acridine orange (AO) and electrochemical sensing of ammonia in liquid phase. Almost 50% photo-catalytic degradation
with AO was observed in the presence of UV sources (250 W) with NPs. β-Fe2O3 NP-coated gold electrodes (GE, surface area 0.0216 cm2) have enhanced ammonia-sensing performances in their electrical response (I–V characterization) for detecting ammonia in liquid phase. The performances of chemical sensor were investigated, and the results
exhibited that the sensitivity, stability, and reproducibility of the sensor improved significantly using β-Fe2O3 NPs on GE surface. The sensitivity was approximately 0.5305 ± 0.02 μAcm−2mM−1, with a detection limit of 21.8 ± 0.1 μM, based on a signal/noise ratio of 3 with short response time. 相似文献
94.
Electrochemical unzipping of multi-walled carbon nanotubes for facile synthesis of high-quality graphene nanoribbons 总被引:1,自引:0,他引:1
Shinde DB Debgupta J Kushwaha A Aslam M Pillai VK 《Journal of the American Chemical Society》2011,133(12):4168-4171
Here we report a remarkable transformation of carbon nanotubes (CNTs) to nanoribbons composed of a few layers of graphene by a two-step electrochemical approach. This consists of the oxidation of CNTs at controlled potential, followed by reduction to form graphene nanoribbons (GNRs) having smooth edges and fewer defects, as evidenced by multiple characterization techniques, including Raman spectroscopy, atomic force microscopy, and transmission electron microscopy. This type of "unzipping" of CNTs (single-walled, multi-walled) in the presence of an interfacial electric field provides unique advantages with respect to the orientation of CNTs, which might make possible the production of GNRs with controlled widths and fewer defects. 相似文献
95.
Aftab Aslam Parwaz Khan Anish Khan Abdullah M. Asiri Naved Azum Malik Abdul Rub Sher Bahadar Khan Mohammed M. Rahman Abdulrahman O. Al-Youbi 《Research on Chemical Intermediates》2014,40(4):1703-1714
The mechanism of dismutation of MnO4 2? via the complex [MTZ–MnO4·OH]2?, formed during the oxidation of metronidazole (MTZ), has been investigated spectrophotometrically at different temperatures. The stoichiometry of the reaction is 1:1, i.e. 1 mol MTZ reacts with 1 mol Mn(VII).The reaction is first order in permanganate, less than first order in [MTZ] and [alkali]. The effects of added products and the dielectric constant and ionic strength of the reaction medium were investigated. The main products were identified by spot test and FT-IR. A mechanism involving a free radical has been proposed. In the equilibrium step MTZ binds to the MnO4 ? species to form a complex (C). Investigation of the reaction at different temperatures enabled determination of the activation data for the slow step of proposed mechanism. The proposed mechanism and the derived rate laws are consistent with the observed kinetics. 相似文献
96.
Muhammad Aslam Noor Khalida Inayat Noor 《Journal of Applied Mathematics and Computing》2008,27(1-2):281-291
In this paper, we show that the general variational inclusions are equivalent to the fixed point problem. We use this equivalence to discuss the existence of the variational inclusions in L p spaces. Using the technique of the updating solution, we suggest some three-step iterative methods for solving the general variational inclusion. We also consider the convergence analysis of the proposed iterative methods under some mild conditions. Since the general variational inclusions include several classes of variational inequalities and optimization problems as special cases, results proved in this paper continue to hold for these problems. 相似文献
97.
Muhammad Aslam Noor Abdellah Bnouhachem 《Journal of Mathematical Analysis and Applications》2005,312(2):514-526
It is well known that the variational inequalities involving the nonlinear term φ are equivalent to the fixed-point problems and the resolvent equations. In this paper, we use these alternative equivalent formulations to suggest and analyze some new self-adaptive iterative methods for solving mixed quasi-variational inequalities. Our results can be viewed as significant extensions of the previously known results for mixed quasi-variational inequalities. An example is given to illustrate the efficiency of the proposed method. 相似文献
98.
Summary We report a new high-resolution absorption spectrum of BaD in the wavelength region (3580÷3760) ? using the third order of
a 21 ft. concave grating spectrograph. Two new electronic states of BaD are reported named asK
2∃-X
2 ∃ at 3750 ? andL
2
II-X
2 ∃ at 3680 ?, respectively. The (0,0),(1,1),(1,0) and (2,1) bands of theL
2-II-X
2∃ state and (0,0) and (1,0) bands of theK
2∃-X
2∃ state have been observed. Vibrational and rotational analysis of these newly observed bands have been carried out and the
corresponding effective vibrational and rotational constants are reported. TheK
2∃ andL
2
II states are tentatively assigned as originating from the 7p atomic state of barium. 相似文献
99.
Symmetries of the first integrals for scalar linear or linearizable secondorder ordinary di?erential equations (ODEs) have already been derived and shown to exhibit interesting properties. One of these is that the symmetry algebra sl(3, IR) is generated by the three triplets of symmetries of the functionally independent first integrals and its quotient. In this paper, we first investigate the Lie-like operators of the basic first integrals for the linearizable maximally symmetric system of two second-order ODEs represented by the free particle system, obtainable from a complex scalar free particle equation, by splitting the corresponding complex basic first integrals and its quotient as well as their associated symmetries. It is proved that the 14 Lie-like operators corresponding to the complex split of the symmetries of the functionally independent first integrals I1, I2 and their quotient I2/I1 are precisely the Lie-like operators corresponding to the complex split of the symmetries of the scalar free particle equation in the complex domain. Then, it is shown that there are distinguished four symmetries of each of the four basic integrals and their quotients of the two-dimensional free particle system which constitute four-dimensional Lie algebras which are isomorphic to each other and generate the full symmetry algebra sl(4, IR) of the free particle system. It is further shown that the (n + 2)-dimensional algebras of the n + 2 first integrals of the system of n free particle equations are isomorphic to each other and generate the full symmetry algebra sl(n + 2, IR) of the free particle system. 相似文献
100.
Wolff JJ Laremore TN Aslam H Linhardt RJ Amster IJ 《Journal of the American Society for Mass Spectrometry》2008,19(10):1449-1458
Electron detachment dissociation (EDD) Fourier transform mass spectrometry has recently been shown to be a powerful tool for
examining the structural features of sulfated glycosaminoglycans (GAGs). The characteristics of GAG fragmentation by EDD include
abundant cross-ring fragmentation primarily on hexuronic acid residues, cleavage of all glycosidic bonds, and the formation
of even- and odd-electron product ions. GAG dissociation by EDD has been proposed to occur through the formation of an excited
species that can undergo direct decomposition or ejects an electron and then undergoes dissociation. In this work, we perform
electron-induced dissociation (EID) on singly charged GAGs to identify products that form via direct decomposition by eliminating
the pathway of electron detachment. EID of GAG tetrasaccharides produces cleavage of all glycosidic bonds and abundant cross-ring
fragmentation primarily on hexuronic acid residues, producing fragmentation similar to EDD of the same molecules, but distinctly
different from the products of infrared multiphoton dissociation or collisionally activated decomposition. These results suggest
that observed abundant fragmentation of hexuronic acid residues occurs as a result of their increased lability when they undergo
electronic excitation. EID fragmentation of GAG tetrasaccharides results in both even- and odd-electron products. EID of heparan
sulfate tetrasaccharide epimers produces identical fragmentation, in contrast to EDD, in which the epimers can be distinguished
by their fragment ions. These data suggest that for EDD, electron detachment plays a significant role in distinguishing glucuronic
acid from iduronic acid. 相似文献