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11.
Yoshiyuki Kawashima Tsuyoshi Usami G. Yu. Golubiatnikov Eizi Hirota 《Journal of Molecular Spectroscopy》2010,263(1):11-20
Rotational spectra of both trans and cis forms of the N-methylformamide normal as well as deuterated (HCONDCH3, referred to as N-D) species were observed by Fourier transform microwave spectroscopy in the frequency region from 5 to 118 GHz. Samples were prepared in the form of a beam by a pulsed jet valve maintained at 50 °C and were introduced in a high-vacuum cavity cell, with either Ne or Ar as a carrier gas at a backing pressure of 100 kPa. The observed spectra were analyzed to yield molecular parameters including rotational constants and barrier, V3, to CH3 internal-rotation: 53.9 (6) and 301 (4) cm−1 for the trans and cis forms of the normal species, respectively, and 41.9 (6) and 309 (4) cm−1 for the trans and cis forms of the N-D species, respectively. Spectra of four trans isotopologues with 13C, 15N, or 18O singly-substituted in the internal-rotation A state were observed and analyzed to derive the rs structure of the trans form. For comparison with the experimental data, ab initio calculations were carried out at MP2/6-31G∗∗ level to derive molecular structure, potential barrier to CH3 internal rotation, and the energy difference between the cis and trans forms. An extensive coupling was found between the CH3 internal rotation and N-H out-of-plane bending, suggesting that the potential function for the CH3 internal-rotation deviates considerably from a simple cos(3α) form. The effects of the V6 term is briefly discussed. 相似文献
12.
The magneto-volume effect is discussed in terms of the recent unified theory of ferromagnetic metals based on general spin fluctuations. Explanations are given for the large negative thermal expansion observed in weakly ferromagnetic metals and for the invar effect in some f.c.c. alloys. Large thermal expansion in nearly ferromagnetic metals is also pointed out. 相似文献
13.
Yoko Usami 《Journal of Graph Theory》1985,9(2):221-234
Suppose G is a graph of n vertices and diameter at most d having the property that, after deleting any vertex, the resulting subgraph has diameter at most 6. Then G contains at least max{n, (4n - 8)/3} edges if 4 ≤ d ≤ 6. 相似文献
14.
Low-temperature growth of ZnO epitaxial films by metal organic chemical vapor deposition 总被引:3,自引:0,他引:3
B.P.?ZhangEmail author N.T.?Binh K.?Wakatsuki N.?Usami Y.?Segawa 《Applied Physics A: Materials Science & Processing》2004,78(1):25-28
ZnO films were grown on Al2O3 (0001) substrates by metal organic chemical vapor deposition at temperatures of Tg=150300 °C. Epitaxial growth was obtained for Tg200 °C. The in-plane orientation of the ZnO unit cells was found to change from a no-twist one with respect to that of the substrate at Tg=200 °C to a 30°-twist one at Tg=300 °C. Absorption and photoluminescence were observed from the film grown at 150 °C, although there was no evidence of epitaxial growth. Films grown at Tg200 °C exhibited smoother surfaces. Moreover, all the films grown at Tg=150300 °C revealed acceptor-related emission peaks, indicating the incorporation of acceptors into the films. PACS 81.15.Gh; 78.55.Et; 78.66.Hf 相似文献
15.
B.P.?ZhangEmail author N.T.?Binh K.?Wakatsuki N.?Usami Y.?Segawa 《Applied Physics A: Materials Science & Processing》2004,79(7):1711-1714
Single-crystalline ZnO tubes were grown on sapphire(0001) substrates by metalorganic chemical vapor deposition at 400 °C. The growth temperature was much lower than that (900–1100 °C) used in previous reports. The tubes were grown along the substrate normal and were characterized by hexagon-shaped cross sections. All of the tubes possessed the same epitaxial relationships with respect to the substrate. Growth pressure was found to play an important role in the formation of ZnO tubes. PACS 61.46.+w; 78.67.-n; 81.15.Gh 相似文献
16.
17.
Hiroyuki Usami 《Archive for Rational Mechanics and Analysis》1995,130(3):277-302
Communicated by J. Serrin 相似文献
18.
We consider fourth order quasilinear ordinary differential equations. Firstly, we classify positive solutions into four types
according to their asymptotic properties. Then we derive existence theorems of positive solutions belonging to each type.
Using these results, we can obtain an oscillation criterion, which is our main objective. Moreover, applying such criteria
for ordinary differential equations to binary elliptic systems, we establish nonexistence theorems for positive solutions. 相似文献
19.
N. Usami J. Arai E. S. Kim K. Ota T. Hattori Y. Shiraki 《Physica E: Low-dimensional Systems and Nanostructures》1998,2(1-4)
Two approaches to control the position and the size of semiconductor islands are proposed. The first method is to perform overgrowth on a cleaved edge of strained multiple quantum wells which acts as a substrate with a periodically modulated lattice constant, thus inducing a periodic strain to the overgrown layer. The second method is to selectively grow islands in specific windows defined by electron beam lithography. Both the methods are applied to the Ge/Si system and the controllability of the Ge island formation is demonstrated. 相似文献
20.