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71.
72.
Jonathan P. Williams Julie Ann Lough Iain Campuzano Keith Richardson Peter J. Sadler 《Rapid communications in mass spectrometry : RCM》2009,23(22):3563-3569
We report the development of an enhanced algorithm for the calculation of collision cross‐sections in combination with Travelling‐Wave ion mobility mass spectrometry technology and its optimisation and evaluation through the analysis of an organoruthenium anticancer complex [(η6‐biphenyl)RuII(en)Cl]+. Excellent agreement was obtained between the experimentally determined and theoretically determined collision cross‐sections of the complex and its major product ion formed via collision‐induced dissociation. Collision cross‐sections were also experimentally determined for adducts of this ruthenium complex with the single‐stranded oligonucleotide hexamer d(CACGTG). Ion mobility tandem mass spectrometry measurements have allowed the binding sites for ruthenium on the oligonucleotide to be determined. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
73.
An equation has been derived for the direct calculation of Vicker's hardness number of glasses from their chemical compositions. The method is based on a consideration of deformation during indentation, which was related to Young's modulus and the average single bond strength of a glass.Excellent agreement is obtained between calculated and measured values of Vicker's hardness number for a variety of glasses. 相似文献
74.
75.
Richard Ducray Pascal Boutron Hervé Germain Maryannick Lamorlette Mickael Maudet Georges Pasquet Iain Simpson 《Tetrahedron letters》2010,51(36):4755-4701
A two-step synthesis of 3-(2-chloropyrimidin-4-yl)imidazo[1,2-a]pyridines is presented. The late stage elaboration of the imidazopyridine through a cyclocondensation allows a rapid access to a variety of substitution patterns. The intermediate enol ethers were obtained from inexpensive reagents in a ligand-free Heck coupling. This methodology has been extended to the formation of pyrazolo[1,5-a]pyridines via a formal 1,3-dipolar cycloaddition. 相似文献
76.
Harding DJ Gruene P Haertelt M Meijer G Fielicke A Hamilton SM Hopkins WS Mackenzie SR Neville SP Walsh TR 《The Journal of chemical physics》2010,133(21):214304
The geometric structures of small cationic rhodium clusters Rh(n)(+) (n = 6-12) are investigated by comparison of experimental far-infrared multiple photon dissociation spectra with spectra calculated using density functional theory. The clusters are found to favor structures based on octahedral and tetrahedral motifs for most of the sizes considered, in contrast to previous theoretical predictions that rhodium clusters should favor cubic motifs. Our findings highlight the need for further development of theoretical and computational methods to treat these high-spin transition metal clusters. 相似文献
77.
Jonathan P. Williams Hazel I. A. Phillips Iain Campuzano Peter J. Sadler 《Journal of the American Society for Mass Spectrometry》2010,21(7):1097-1106
The three-dimensional conformation of a protein is an important property and plays a key role in its biological activity.
We show here that ion mobility-mass spectrometry (IM-MS) can be used to detect conformational changes in the protein ubiquitin
in the gas phase induced by reaction with the anticancer drug cisplatin. The primary adduct was ubiquitin-{Pt(NH3)2} under denaturing conditions. Up to three different conformations appear to be generated upon platination depending on the
charge state. The collision cross-sections (Ω) for each conformation indicate that the conformations of the platinated protein
are contracted in size compared with unmodified ubiquitin with generally smaller Ω values. Ion mobility-tandem MS allowed
determination of the platinum binding site without a requirement for prior Chromatographic separation. A rapid 30-min digestion
of cisplatin-modified ubiquitin with trypsin allowed the platination site to be identified as the N-terminal methionine following
low-energy collision-induced dissociation (CID) studies of the modified peptide. The data were generated using a Traveling-Wave
based ion mobility-MS approach. Such cisplatin-induced shape changes may have a significant effect on its function in vivo.
This work highlights the usefulness of the ion-mobility mass spectrometry technique for shedding new light on such protein
interactions. 相似文献
78.
On the inversion of diffusion NMR data: Tikhonov regularization and optimal choice of the regularization parameter 总被引:1,自引:0,他引:1
Day IJ 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,211(2):178-185
The analysis of diffusion NMR data in terms of distributions of diffusion coefficients is hampered by the ill-posed nature of the required inverse Laplace transformation. Na?ve approaches such as multiexponential fitting or standard least-squares algorithms are numerically unstable and often fail. This paper updates the CONTIN approach of the application of Tikhonov regularization to stabilise this numerical inversion problem and demonstrates two methods for automatically choosing the optimal value of the regularization parameter. These approaches are computationally efficient and easy to implement using standard matrix algebra techniques. Example analyses are presenting using both synthetic data and experimental results of diffusion NMR studies on the azo-dye sunset yellow and some polymer molecular weight reference standards. 相似文献
79.
At the LHC and Tevatron strong initial-state radiation (ISR) plays an important role. It can significantly affect the partonic luminosity available to the hard interaction or contaminate a signal with additional jets and soft radiation. An ideal process to study ISR is isolated Drell-Yan production, pp → X?+ ?- without central jets, where the jet veto is provided by the hadronic event shape beam thrust τB. Most hadron collider event shapes are designed to study central jets. In contrast, requiring τ B < 1 provides an inclusive veto of central jets and measures the spectrum of ISR. For τ B < 1 we carry out a resummation of α s(n)ln(m)τ B corrections at next-to-next-to-leading-logarithmic order. This is the first resummation at this order for a hadron-hadron collider event shape. Measurements of τ B at the Tevatron and LHC can provide crucial tests of our understanding of ISR and of τ B's utility as a central jet veto. 相似文献
80.
Physical Properties of Sol-Gel Coatings 总被引:3,自引:0,他引:3
One of the most important applications of sol-gel technology is the fabrication of coatings. This is because of the possibility of applying oxide coatings with practically all types of chemical compositions at low ambient temperatures on many substrates of various shapes through the use of liquid solutions. Both oxides and different types of organic-inorganic hybrid coatings have been reported. Both oxides and hybrid coatings are usually amorphous at ambient temperatures but some oxides can be converted to the crystalline phase with heating. Regardless of the intended applications of the coatings their physical properties are always of importance. For instance, an anti-reflective coating for an automobile mirror is of little practical value unless it is fairly scratch-resistant. In this review which covers published information in the past fifteen years, some of the more important results of physical properties of sol-gel derived coatings are discussed firstly for oxides and then for organic-inorganic hybrids. It appears that properties such as the hardness of oxide coatings are inadequate unless the heat-treatment temperatures are in excess of about 400°C. The hybrid coatings, especially when they contain a dispersed phase of a hard solid like colloidal silica, can be processed at temperatures below about 150°C and can improve the performance of organic plastics such as the polycarbonates. There is insufficient scientific understanding of the relationship between physical properties and other interdependent variables such as processing conditions, chemistry and coating thickness. More research in this area will undoubtedly contribute to the availability of better and new coatings via the sol-gel approach. 相似文献