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61.
State-resolved collision energy dependence of Penning ionization cross sections of acetylene (C2H2) and ethylene (C2H4) with He*(2 3S) metastable atoms was observed in a wide collision energy range from 20 to 350 meV. A recently developed discharge nozzle source with a liquid N2 circulator was employed for the measurements in the low-energy range from 20 to 80 meV. Based on classical trajectory calculations for the energy dependence of the partial ionization cross sections, anisotropic potential energy surfaces for the present systems were obtained by optimizing ab initio model potentials for the chemically related systems Li+C2H2 and C2H4. In the case of C2H2, the global minimum was found to be located around the H atom along the molecular axis with a well depth of 48 meV (ca. 1.1 kcal/mol). On the other hand, a dominant attractive well with a depth of 62 meV (ca. 1.4 kcal/mol) was found in the piCC electron region of C2H4. These findings were discussed in connection with orbital interactions between molecular orbitals of the target molecules and atomic orbitals of the metastable atom. It is concluded that sigma-type unoccupied molecular orbitals of C2H2 and a piCC-type highest occupied molecular orbital of C2H4 play a significant role for the attractive-site preference of sigma direction in C2H2 and pi direction in C2H4, respectively. 相似文献
62.
63.
Shinji Kishimoto Yuta Tsunematsu Shinichi Nishimura Yutaka Hayashi Akira Hattori Hideaki Kakeya 《Tetrahedron》2012,68(27-28):5572-5578
Tumescenamide C, a new cyclic lipodepsipeptide, was isolated from a culture broth of an actinomycete Streptomyces sp. KUSC_F05. Tumescenamide C was a congener of tumescenamides A and B, representing a sixteen-membered ring system, consisting of two proteinogenic and three non-proteinogenic amino acids, to which a methyl-branched fatty acid was attached. The planar structure was determined by spectroscopic analysis, while its absolute stereochemistry was determined by chemical degradation and asymmetric synthesis. Tumescenamide C exhibited antimicrobial activity with high selectivity against Streptomyces species. 相似文献
64.
Tuning of band gaps for a two-dimensional piezoelectric phononic crystal with a rectangular lattice 总被引:1,自引:0,他引:1
Kikuo Kishimoto 《Acta Mechanica Sinica》2009,25(1):65-71
In this paper, the elastic wave propagation in a two-dimensional piezoelectric phononic crystal is studied by considering the mechanic-electric coupling. The generalized eigenvalue equation is obtained by the relation of the mechanic and electric fields as well as the Bloch-Floquet theorem. The band structures of both the in-plane and anti-plane modes are calculated for a rectangular lattice by the planewave expansion method. The effects of the lattice constant ratio and the piezoelectricity with different filling fractions are analyzed. The results show that the largest gap width is not always obtained for a square lattice. In some situations, a rectangular lattice may generate larger gaps. The band gap characteristics are influenced obviously by the piezoelectricity with the larger lattice constant ratios and the filling fractions. 相似文献
65.
Experimental investigation of the low cycle fatigue crack propagation in PC/ABS polymer blends 总被引:1,自引:0,他引:1
Low cycle fatigue crack propagation (FCP) behavior of two PC/ABS blends with a weight ratio of PC to ABS being 80/20 and 60/40,
respectively, is investigated. Experiments are carried out by using standard compact tension (CT) specimens. The fracture
surfaces are examined with a scanning electron microscope (SEM). It is shown that the FCP resistance of PC/ABS blend with
20% ABS particles is higher than that of PC/ABS blend with 40% ABS particles. It is found that proper ABS particle content
can result in the toughening of PC/ABS blends through particle cavitation and shear yielding in matrix.
Project supported by the Excellent Young Teachers Program and the Research Foundation for Doctoral Project of the Ministry
of Education of China. 相似文献
66.
Tadatomi Nishikubo Atsushi Kameyama Kousuke Tsutsui Shinichi Kishimoto 《Journal of polymer science. Part A, Polymer chemistry》2001,39(9):1481-1494
Calixarene derivatives 1a , 1b , and 1c containing pendant tert‐butoxycarbonyl (t‐BOC) groups were synthesized in 81, 93, and 83% yields, respectively, by the reaction of C‐methylcalix[4]resorcinarene (CRA), p‐methylcalix[6]arene (MCA), and p‐tert‐butylcalix[8]arene (BCA) with di‐tert‐butyl dicarbonate using triethylamine as a base in pyridine. Calixarene derivatives 2a , 2b , and 2c containing pendant trimethylsilyl ether (TMSE) groups were obtained in 58, 50, and 82% yields, respectively, by the reaction of CRA, MCA, and BCA with 1,1,1,3,3,3‐hexamethyldisilazane using chlorotrimethylsilane as an accelerator in tetrahydrofuran. Calixarene derivatives 3a , 3b , and 3c containing pendant cyclohexenyl ether (CHE) groups were also prepared in 65, 78, and 84% yields, respectively, by the reaction of CRA, MCA, and BCA with 3‐bromocyclohexene using potassium hydroxide as a base as well as tetrabutylammonium bromide as a phase‐transfer catalyst in N‐methyl‐2‐pyrolidone. The photoinduced deprotection of calixarene derivatives 1a – c was examined with bis‐[4‐(diphenylsulfonio)phenyl]sulfide bis(hexafluorophosphate) as a photoacid generator on UV irradiation followed by heating in the film state, and it was found that the deprotection of the t‐BOC groups of 1a proceeded smoothly in high conversion. The deprotection rates of the t‐BOC groups of 1b and 1c were much lower than that of 1a under the same irradiation conditions. The photoinduced deprotection of calixarenes 2b – c containing tetramethylsilane groups as well as 3a – c containing CHE groups were also examined under similar reaction conditions in the film state, and it was found that the deprotection rates of calixarenes 2b – c and 3a – c were lower than those of the corresponding 1a – c calixarenes. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1481–1494, 2001 相似文献
67.
Nobuo Ishizawa Reiko Yamashita Shuji Oishi James R. Hester Shunji Kishimoto 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1006-1009
The triclinic superstructure of a small crystal of LiCa2Nb3O10, lithium dicalcium triniobium decaoxide, has been investigated by synchrotron X‐ray diffraction. The unit cell is an almost rectangular parallelepiped, although there is a 0.245° offset from orthogonality for β. The structure essentially belongs to a homologous series of Li[Nan?3Ca2NbnO3n+1] with n = 3, where the moiety in square brackets has a perovskite‐type slab structure. The superstructure has a doubled unit‐cell volume with respect to the tetragonal aristotype. The NbO6 octahedra are rotated about axes parallel to [110] by approximately 10°. Adjacent slabs are connected by Li atoms and are geometrically related by 42 pseudosymmetry lying parallel to c . There are twice as many sites as Li atoms, providing a variation of population at these Li sites. 相似文献
68.
M. Yamazaki N. Kishimoto K. Ohno 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):47-57
Collisional ionization of styrene (phenylethylene), 2-vinylpyridine, and
4-vinylpyridine with metastable He*(23S) atoms were studied by means of
collision-energy/electron-energy resolved two-dimensional Penning
ionization electron spectroscopy. Collision energy dependence of partial
ionization cross-sections, which reflects the anisotropic interactions
between a He*(23S) atom and the target molecules, indicates that
attractive interaction for the out-of-plane access of a He*(23S) atom
to phenyl group is stronger than that for the out-of-plane access to vinyl
group. Moreover, it was found for vinylpyridines that the attractive
interaction around π electrons became weaker than that for styrene, and
that the attractive interaction for the in-plane access to the nitrogen atom
is stronger than that for out-of-plane π-directions. However, in
2-vinylpyridine, the hydrogen atom of vinyl group prevents a He*(23S)
atom from approaching to the nitrogen atom along in-plane directions, and
thus the attractive interactions around the nitrogen atom were shielded by
the vinyl group. The experimentally observed anisotropic interactions were
qualitatively supported with ab initio model interaction potential calculations
between a Li (He*(23S)) atom and the target molecule. Concerning with
electronic structures of investigated molecules, the assignment of Penning
ionization electron spectrum for 4-vinylpyridine was discussed on the basis
of different behavior of collision-energy dependence of partial ionization
cross-sections, and the satellite ionization band in Penning ionization
electron spectra was also reported for styrene. 相似文献
69.
70.
This paper studies an initial boundary value problem for a one-dimensional isentropic model system of compressible viscous gas with large external forces, represented by v
t
–u
x
=0,u
t
+(av
–)
x
=(u
x
/v)
x
+f(
0
x
vdx,t), with (v(x, 0),u(x, 0))= (v
0(x),u
0(x)),u(0,t)=u(1,t)=0. Especially, the uniform boundedness of the solution in time is investigated. It is proved that for arbitrary large initial data and external forces, the problem uniquely has an uniformly bounded, global-in-time solution with also uniformly positive mass density, provided the adiabatic constant (>1) is suitably close to 1. The proof is based on L
2-energy estimates and a technique used in [9]. 相似文献