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排序方式: 共有269条查询结果,搜索用时 31 毫秒
261.
Kazuhiro Mori Ryoji Kiyanagi Kenji Iwase Takashi Sato Masaaki Sugiyama Toshiharu Fukunaga 《Journal of solid state chemistry》2006,179(11):3286-3294
In order to study the crystal structure of β‐Ca2SiO4, time-of-flight neutron powder diffraction experiments were carried out at temperatures between room temperature (RT) and 600 °C. Rietveld refinement at RT has shown that β‐Ca2SiO4 is monoclinic based on P21/n symmetry and two different types of Ca sites, Ca(1) and Ca(2). All interatomic distances within 3 Å were calculated, with the valences of Ca(1) with seven CaO bonds and Ca(2) with eight were estimated to be 1.87+ and 2+ by the Zachariasen-Brown-Altermatt formula (bond valence sum). Applying charge neutrality the two charge states of Ca in β‐Ca2SiO4 are [Ca(1)SiO4]2− and Ca(2)2+, respectively. Furthermore, the [Ca(1)SiO4]2− unit has the shortest Ca-O distance, and its length kept constant at 2.23 Å at all temperatures. In the short-range structure analysis at RT, the shortest Ca-O bond was also observed in a radial distribution function. These results imply that the [Ca(1)SiO4]2− unit has covalency on the shortest Ca-O in addition to Si-O. 相似文献
262.
Nakaya M Kanehara M Teranishi T 《Langmuir : the ACS journal of surfaces and colloids》2006,22(8):3485-3487
One-pot synthesis of FePt nanoparticles larger than 5 nm with controlled composition has been developed by the polyol reduction of platinum acetylacetonate and iron acetylacetonate in excess ligands. The obtained large FePt nanoparticles (6.1 +/- 0.6 nm Fe36Pt64, 5.8 +/- 0.7 nm Fe44Pt56, and 5.1 +/- 0.7 nm Fe49Pt51 nanoparticles) were thermally more stable than the small ones and were hard to coalesce in the in-plane direction for their 2D superlattice. 相似文献
263.
Toshiharu Kawasaki 《Czechoslovak Mathematical Journal》2009,59(2):381-399
In this paper we define the derivative and the Denjoy integral of mappings from a vector lattice to a complete vector lattice
and show the fundamental theorem of calculus.
相似文献
264.
The dry beads of chelate resin-metal complexes have been prepared from metal ions and the chelate resin containing iminodiacetic acid moieties. The surface area of the chelate resin can be increased both by washing with an organic solvent miscible with water and by complexing with multi-valent cations. Palladium clusters are supported on the chelate resin-metal complexes by two methods, in which the order is reversed between “complexing of metal ions” and “supporting of palladium clusters”. The supported palladium clusters catalyze the hydrogenation of C=C bonds, and the catalytic activity greatly depends on the metal ions used for the complexation. In the case of typical metal ions, the complexing of metal ions after supporting of palladium clusters makes the surface area of the resin increase, but makes the catalytic activity decrease compared with the reverse order. In the case of lanthanoid ions, on the other hand, the same order makes both the surface area and the catalytic activity increase. 相似文献
265.
Madhu Menon Ernst Richter Padma Raghavan Keita Teranishi 《Superlattices and Microstructures》2000,27(5-6):577-581
The stability of quasi-one-dimensional structures of carbon is investigated using a generalized tight-binding molecular-dynamics scheme. Large-scale simulations are made possible by the parallel implementation of the diagonalization routines. Our results show that these structures can be stable provided that their geometries consist of a core of four-fold coordinated atoms, surrounded by a three-fold coordinated outer surface accommodating one of the most stable reconstructions of bulk diamond structure. 相似文献
266.
Takashi Sugimoto Kazuhisa Ikemoto Shizuaki Murata Masahiro Tazawa Takahide Nomura Yasumichi Hagino Hiroshi Ichinose Toshiharu Nagatsu 《Helvetica chimica acta》2001,84(4):918-927
The structure of the native pteridine in Tetrahymena pyriformis was determined as (6R)‐5,6,7,8‐tetrahydro‐D ‐monapterin (=(6R)‐2‐amino‐5,6,7,8‐tetrahydro‐6‐[(1R,2R)‐1,2,3‐trihydroxypropyl]pteridin‐4(3H)‐one; 4 ). First, the configuration of the 1,2,3‐trihydroxypropyl side chain was confirmed as D ‐threo by the fluorescence‐detected circular dichroism (FDCD) spectrum of its aromatic pterin derivative 2 obtained by I2 oxidation (Fig. 1). The configuration at the 6‐position of 4 was determined as (R) by comparison of its hexaacetyl derivative 6 with authentic (6R)‐ and (6S)‐hexaacetyl‐5,6,7,8‐tetrahydro‐D ‐monapterins 6 and 7 , respectively, in the HPLC, LC/MS, and LC‐MS/MS (Figs. 3 – 6). (6R)‐5,6,7,8‐Tetrahydro‐D ‐monapterin ( 4 ) is a newly discovered natural tetrahydropterin. 相似文献
267.
268.
Optical Review - To visualize the microscopic internal structure of cells, some conventional methods exist in the literature, such as irradiating fluorescent substances with light that maintains... 相似文献
269.
Viktor M. Rozenbaum Irina V. Shapochkina Yoshiaki Teranishi Henryk A. Witek Leonid I. Trakhtenberg 《中国化学会会志》2023,70(3):209-218
We present a review of analytical approaches involved in developing the ratchet theory, which are based on the model of extremely asymmetric sawtooth potential. Analytical expressions are given for the average velocity of ratchets which operate in various motion modes, namely, motion induced by dichotomous half-period shifts of potential profiles, adiabatic and high-temperature modes, and motion induced by small fluctuations of an arbitrary type. The presence of jumps in the periodic extremely asymmetric sawtooth potential profile leads to a number of features of the obtained solutions which follow from the competition of the reverse sliding time tending to infinity with high fluctuation frequencies. The resulting dependences of the average velocity on the ratchet parameters clearly demonstrate that the motion direction can be controlled by tuning the frequency and temperature. The heuristic value of the presented models for controlling nanoparticle transport is discussed. 相似文献