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91.
2H-Benzo[b]thiete 1 reacts with cyclopentadiene 3 in consecutive [8π + 2π]cycloadditions yielding the condensed heterocycles 6–8 . Tetracyclone 9 on the other hand gives only the monoadduct 10 . An [8π + 8π]cycloaddition can be observed for 1 and diphenylisobenzofuran 11 . The related π system 13 shows again consecutive [477π + 27π]processes ( 1 + 13 ← 14, 15 ). 相似文献
92.
93.
At DIII-D, a slot divertor concept, called small-angle-slot (SAS), is under development, aiming to enable detachment at relatively low plasma edge density. We report on simulations using the SOLPS-ITER two-dimensional edge code to examine the performance of conceptual “SAS 2” slot configurations. The focus of the analysis is on E × B drift effects on upstream density at detachment (UDD), with detachment marked by electron temperature Te ≤ 3 eV at the outer strike point (OSP). With toroidal field such that radial E × B drift carries particles from the OSP towards the private flux region (PFR), placing the OSP near the inner slot wall gives ≈20% lower UDD than having the OSP near the outer wall. The inner wall effectively traps the radial E × B drift flux, resulting in low Te and associated radial electric field in the PFR, and thus small losses from the slot to the inner target via poloidal E × B drift flux. With toroidal field reversed such that radial E × B drift is reversed, OSP placement near the inner wall gives ≈10% lower UDD than OSP placement near the outer wall. Although radial E × B flux is from the OSP towards the outer wall, this flux largely escapes the slot, raising the UDD. A change in the slot shaping is suggested with the goal of eliminating such E × B -driven particle losses from the slot. 相似文献
94.
95.
Jan-Falk Kannengießer Max Briesenick Dr. Dennis Meier Dr. Volker Huch Dr. Bernd Morgenstern Prof. Dr. Guido Kickelbick 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(66):16461-16476
Organosilanols typically show a high condensation tendency and only exist as stable isolable molecules under very specific steric and electronic conditions at the silicon atom. In the present work, various novel representatives of this class of compounds were synthesized by hydrolysis of alkoxy- or chlorosilanes. Phenyl, 1-naphthyl, and 9-phenanthrenyl substituents at the silicon atom were applied to systematically study the influence of the aromatic substituents on the structure and reactivity of the compounds. Chemical shifts in 29Si NMR spectroscopy in solution, correlated well with the expected electronic situation induced by the substitution pattern on the Si atom. 1H NMR studies allowed the detection of strong intermolecular hydrogen bonds. Single-crystal X-ray structures of the alkoxides and the chlorosilanes are dominated by π-π interactions of the aromatic systems, which are substituted by strong hydrogen bonding interactions representing various structural motifs in the respective silanol structures. 相似文献
96.
D. J. Meier 《Journal of Macromolecular Science: Physics》2013,52(2):181-189
The swelling behavior of a lamellar domain system of an ABA block copolymer is treated, with account taken of the relative population of the B chains as “loops” and “bridges.” The swelling behavior is not a sensitive function of these configurations, since both types in condensed systems are elastically effective, in contrast to the behavior of isolated chains. 相似文献
97.
98.
Meier MS Bergosh RG Gallagher ME Spielmann HP Wang Z 《The Journal of organic chemistry》2002,67(17):5946-5952
The fulleride dianions C(60)(2-) and C(70)(2-) were generated by deprotonation of the corresponding hydrogenated fullerenes, 1,2-C(60)H(2) and 1,2-C(70)H(2). These anions were prepared in the presence of a variety of alkylating agents, and mono- or dialkylated products were obtained. Alkylation was not successful with sulfonate ester alkylating agents. Deprotonation of monoalkylated compounds, followed by second alkylation with a different alkylating agent, produced heterodialkylated compounds. The monoalkyated material was invariably the 1,2-isomers, while the dialkylated materials were generally 1,4-isomers, although some 1,2-isomer was observed in the C(70) context. The major product from alkylation of C(70)(2-) was the 7,23-isomer 13a, a structure where the alkylation took place near the equator of the fullerene cage, rather than at the more strained carbons near the poles. 相似文献
99.
100.
A. O. Vyrodov J. Heinze M. Dillmann U. E. Meier W. Stricker 《Applied physics. B, Lasers and optics》1995,61(5):409-414
Laser-Induced Fluorescence (LIF) excitation spectra in the NOA–X (0-0) band were used for temperature measurements in the postflame region of high-pressure CH4/air flames. To improve the quality of the measured spectra and to perform reliable line-shape measurements, the initial mixture was doped with approximately 400 ppm NO. At pressures up to 18 bar, excellent agreement was obtained between NO LIF temperatures and NARS/rotational Raman temperatures. Effective broadening coefficients were also determined in these flames. Problems with quantitative concentration measurements of NO and single-pulse temperature measurements at high pressures are discussed. 相似文献