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排序方式: 共有920条查询结果,搜索用时 593 毫秒
291.
James Rosario Gambino Donald William Schwendeman 《Combustion Theory and Modelling》2016,20(6):1088-1117
The dynamics of detonation in a granular explosive following a piston impact is examined computationally for a two-phase model. Different choices are considered for equations of state and reaction rate. Of special interest is the behaviour of the run-to-detonation distance as a function of the initial porosity of the explosive, for which new experimental information has recently become available. It is found that this response can vary both qualitatively and quantitatively depending upon the constitutive input to the model. Computations based upon up-to-date equation-of-state and reaction-rate information for the explosive PBX-9501 show that the response of the run-to-detonation distance as a function of the initial porosity is in the shape of an inverted U, which is in qualitative agreement with the latest experiments. Mechanisms responsible for this behaviour are identified. 相似文献
292.
Dr. Pablo Labra-Vázquez Ricardo Flores-Cruz Aylin Galindo-Hernández Dr. Justo Cabrera-González Cristian Guzmán-Cedillo Dr. Arturo Jiménez-Sánchez Dr. Pascal G. Lacroix Dr. Rosa Santillan Dr. Norberto Farfán Dr. Rosario Núñez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(69):16530-16540
A set of BODIPY-carboranyl dyads synthesized by a Sonogashira cross-coupling reaction, where different C-substituted ortho- and meta-carboranyl fragments have been linked to a BODIPY fluorophore is described. Chemical, photophysical and physicochemical analyses are presented, including NMR and single XRD experiments, optical absorption/emission studies and partition coefficient (log P) measurements. These studies, supported by DFT computations (M06-2X/6-31G**), provide an explanation to the largely divergent cell income that these fluorescent carboranyl-based fluorophores display, for which a structural or physicochemical explanation remains elusive. By studying the cell uptake efficiency and subcellular localization for our set of dyads on living HeLa cells, we tracked the origins of these differences to significant variations in their static dipole moments and partition coefficients, which tune their ability to interact with lipophilic microenvironments in cells. Remarkably, m-carboranyl-BODIPY derivatives with a higher lipophilicity are much better internalised by cells than their homologous with o-carborane, suggesting that m-isomers are potentially better theranostic agents for in vitro bioimaging and boron carriers for boron neutron capture therapy. 相似文献
293.
Dr. Ru-Jin Li Dr. Farzaneh Fadaei-Tirani Dr. Rosario Scopelliti Prof. Kay Severin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(36):9439-9445
Spherical assemblies of the type [PdnL2n]2n+ can be obtained from PdII salts and curved N-donor ligands, L. It is well established that the bent angle, α, of the ligand is a decisive factor in the self-assembly process, with larger angles leading to complexes with a higher nuclearity, n. Herein, we report heteroleptic coordination cages of the type [PdnLnL′n]2n+, for which a similar correlation between the ligand bent angle and the nuclearity is observed. Tetranuclear cages were obtained by combining [Pd(CH3CN)4](BF4)2 with 1,3-di(pyridin-3-yl)benzene and ligands featuring a bent angle of α=120°. The use of a dipyridyl ligand with α=149° led to the formation of a hexanuclear complex with a trigonal prismatic geometry; for linear ligands, octanuclear assemblies of the type [Pd8L8L′8]16+ were obtained. The predictable formation of heteroleptic PdII cages from 1,3-di(pyridin-3-yl)benzene and different dipyridyl ligands is evidence that there are entire classes of heteroleptic cage structures that are privileged from a thermodynamic point of view. 相似文献
294.
295.
Justo Cabrera‐González Dr. Laura Cabana Dr. Belén Ballesteros Dr. Gerard Tobias Dr. Rosario Núñez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(15):5096-5101
An efficient process to produce boron cluster–graphene oxide nanohybrids that are highly dispersible in water and organic solvents is established for the first time. Dispersions of these nanohybrid materials in water were extraordinarily stable after one month. Characterization of hybrids after grafting of appropriate cobaltabisdicarbollide and closo‐dodecaborate derivatives onto the surface of graphene oxide (GO) was done by FT‐IR, XPS, and UV/Vis. Thermogravimetric analysis (TGA) clearly shows a higher thermal stability for the modified‐GO nanohybrids compared to the parent GO. Of particular note, elemental mapping by energy‐filtered transmission electron microscopy (EFTEM) reveals that a uniform decoration of the graphene oxide surface with the boron clusters is achieved under the reported conditions. Therefore, the resulting nanohybrid systems show exceptional physico‐chemical and thermal properties, paving the way for an enhanced processability and further expanding the range of application for graphene‐based materials. 相似文献
296.
297.
We investigate the scattering of compressional waves from an infinite, circular-cylindrical obstacle, and the excitation during the scattering process of surface waves that propagate along helical paths over the cylinder surface. For the case of a rigid or soft obstacle, the surface waves are external, and are obtained via the use of a Watson transformation. For the case of a penetrable cylinder, additional internal, resonant surface waves are generated for which the phase and group velocity dispersion curves can be obtained from the Resonance Scattering Theory. We perform a detailed study of certain refraction effects which take place upon the generation of the surface waves by the incident plane wave. 相似文献
298.
O. Mayol O. Rosario R. Blanco I. Colon 《International journal of environmental analytical chemistry》2013,93(2-4):221-237
Abstract The high volatility and low water solubility of volatile organic compounds (VOCs), make the collection of representative samples difficult. The standard grab sampling method only gives information of that moment in time when the sample is taken. When the composition of VOCs is varying, continuous composite sampling will give a more representative sample. However, no thorough evaluation of its use for VOCs has been reported. The use of an automatic continuous composite sampler for the analysis of VOCs in water was studied. The causes and magnitude of the VOCs losses during the sampling process were determined. Adsorbent cartridges were used to trap the VOCs escaping from solution during the sampling process. Sorption phenomena occurring on the containers and/or tubings were also evaluated. Sorption losses were much more significant than volatilization losses. The results indicate that a modified version of this sampler can be an alternative for the long term sampling of water for VOC analysis. 相似文献
299.
Clément Schouwey Dr. Rosario Scopelliti Prof. Kay Severin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(20):6274-6281
The synthesis of a cylindrical, imine‐based cage composed of two trimeric metallamacrocycles is described. The cage acts as a heterotopic receptor for alkali metal cations. The small cations Li+, Na+, and K+ bind to the outside of the cage with good selectivity for Li+, whereas the larger cations Rb+ and Cs+ are bound inside the cage to form unusual π complexes with a good selectivity for Cs+. Negative heterotopic cooperativity between the two binding sites is observed. The complexation of Cs+ is associated with a color change, which enables the cage to be used as a specific sensor for Cs+. 相似文献
300.
Nana N. Barbakadze Rachel A. Jones Nicole Rivera Rosario Nanuli Sh Nadaraia Meri L. Kakhabrishvili C. Dennis Hall Alan R. Katritzky 《Tetrahedron》2014
The modification of oximes, including 5α-steroids, with N-protected amino acids, in solution phase, using benzotriazole methodology is reported. 相似文献