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311.
Kiyoshi Sawada Eiji Takahashi Tomokazu Horie Keiichi Satoh 《Monatshefte für Chemie / Chemical Monthly》2001,132(11):1439-1450
Summary. The distribution of tetraalkylammonium ions (C
n
H
2n+1
)4N+ (R
+, TAAn
+, n = 4–7) with picrate ion (pic
−) and inorganic anions X
−, (Cl−, Br−, ClO−
4), into various inert organic solvents was studied at 25.0°C. The distribution data were analyzed by taking into consideration
the distribution of ion pairs, R
+ · X
−, and the dimerization of the ion pairs, (R
+ · X
−)2, in the organic phase. The ion-pair, distribution constant, K
dist, increases with increasing chain length of the tetraalkylammonium ion and with increasing ionic radius of the anion. The
values of K
dist show a good correlation with the E
T value of solvent, i.e. the solvation ability with respect to the anion, and smoothly increase with increasing E
T. The effect of the solvent on the dimerization constants, K
dim, is markedly different between the ion pairs of picrate ion and inorganic anions. In the case of picrate, K
dim significantly decreases with decreasing length of the alkyl chain of the tetraalkylammonium ion, but hardly changes by changing
the solvent. On the other hand, in the case of ion pairs of inorganic anions the value of K
dim decreases with decreasing E
T and is almost constant for all anions. These results were reasonably explained by the difference of the solvation of the
anion moieties of the monomeric and dimeric ion pairs.
Received May 15, 2001. Accepted (revised) July 18, 2001 相似文献
312.
Kiyoshi Sawada Eiji Takahashi Tomokazu Horie Keiichi Satoh 《Monatshefte für Chemie / Chemical Monthly》2001,36(4):1439-1450
The distribution of tetraalkylammonium ions (C n H 2n+1 )4N+ (R +, TAAn +, n = 4–7) with picrate ion (pic −) and inorganic anions X −, (Cl−, Br−, ClO− 4), into various inert organic solvents was studied at 25.0°C. The distribution data were analyzed by taking into consideration the distribution of ion pairs, R + · X −, and the dimerization of the ion pairs, (R + · X −)2, in the organic phase. The ion-pair, distribution constant, K dist, increases with increasing chain length of the tetraalkylammonium ion and with increasing ionic radius of the anion. The values of K dist show a good correlation with the E T value of solvent, i.e. the solvation ability with respect to the anion, and smoothly increase with increasing E T. The effect of the solvent on the dimerization constants, K dim, is markedly different between the ion pairs of picrate ion and inorganic anions. In the case of picrate, K dim significantly decreases with decreasing length of the alkyl chain of the tetraalkylammonium ion, but hardly changes by changing the solvent. On the other hand, in the case of ion pairs of inorganic anions the value of K dim decreases with decreasing E T and is almost constant for all anions. These results were reasonably explained by the difference of the solvation of the anion moieties of the monomeric and dimeric ion pairs. 相似文献
313.
The k
0 standardization method has been studied and applied at JAERI for the accurate determination of multielements by neutron-induced prompt gamma-ray analysis (PGA). The k
0 factors for 26 elements using Cl as a comparator were measured by the cold and thermal neutron guided beams of JRR-3M with an uncertainty less than 3% except for a few elements. The k
0 factors for most elements obtained with both cold and thermal neutrons agreed within 3%, and agreed also with those measured at other cold and thermal neutron guided beams within 10%, except for a few elements. Multielement determinations in reference materials were performed using the k
0 factors obtained to evaluate the accuracy and precision of this work. 相似文献
314.
Hitoshi Okubo Fei Feng Daisuke Nakano Tomokazu Hirata Masahiko Yamaguchi Tokuji Miyashita 《Tetrahedron》1999,55(52):116-14864
We previously reported that an optically active cyclic amide consisting of a helical chiral 1,12-dimethylbenzo[c]phenanthrene-5, 8-dicarboxylic acid forms a stable monolayer on the water surface, and that the monolayer can be transferred on a solid support giving optically active Langmuir-Blodgett (LB) films. In this study, several related amides were synthesized, and their monolayer behaviors were investigated with expectation to prepare optically active LB films possessing functional groups. The result indicates that the cyclic amide structure and cyclohexyl moiety are essential for the formation of stable monolayer on the water surface. N-Alkylation of the secondary amide does not seriously affect the formation of monolayer, and chiral LB films are obtained by N,N-bis(3-meroaptopropyl) derivative of the cyclic amide. 相似文献
315.
Novel type of monolayer and multilayer of normally aligned,π-conjugated system with no alkyl chain was realized consisting of oligo-acene molecules by Langmuir-Blodgett technique. 相似文献
316.
Tomokazu Ito Akihiko Nakatsuka Hideki Maekawa Akira Yoshiasa Takamitsu Yamanaka 《无机化学与普通化学杂志》2000,626(1):42-49
The crystal structures of MgAl2–xGaxO4 (0 ≤ x ≤ 2) spinel solid solutions (x = 0.00, 0.38, 0.76, 0.96, 1.52, 2.00) were refined using 27Al MAS NMR measurements and single crystal X‐ray diffraction technique. Site preferences of cations were investigated. The inversion parameter (i) of MgAl2O4 (i = 0.206) is slightly larger than given in previous studies. It is considered that the difference of inversion parameter is caused by not only the difference of heat treatment time but also some influence of melting with a flux. The distribution of Ga3+ is little affected by a change of the temperature from 1473 K to 973 K. The degree of order‐disorder of Mg2+ or Al3+ between the fourfold‐ and sixfold‐coordinated sites is almost constant against Ga3+ content (x) in the solid solution. A compositional variable of the Ga/(Mg + Ga) ratio in the sixfold‐coordinated site has a constant value through the whole compositional range: the ratio is not influenced by the occupancy of Al3+. The occupancy of Al3+ is independent of the occupancy of Ga3+, though it depends on the occupancy of Mg2+ according to thermal history. The local bond lengths were estimated from the refined data of solid solutions. The local bond length between specific cation and oxygen corresponds with that expected from the effective ionic radii except local Al–O bond length in the fourfold‐coordinated site and local Mg–O bond length in the sixfold‐coordinated site. The local Al–O bond length in the fourfold‐coordinated site (1.92 Å) is about 0.15 Å longer than the expected bond length. This difference is induced by a difference in site symmetry of the fourfold‐coordinated site. The nature that Al3+ in spinel structure occupies mainly the sixfold‐coordinated site arises from the character of Al3+ itself. The local Mg–O bond length in the sixfold‐coordinated site (2.03 Å) is about 0.07 Å shorter than the expected one. Difference Fourier synthesis for MgGa2O4 shows a residual electron density peak of about 0.17 e/Å3 in height on the center of (Ga0.59 Mg0.41)–O bond. This peak indicates the covalent bonding nature of Ga–O bond on the sixfold‐coordinated site in the spinel structure. 相似文献
317.
Akira Yoshiasa Genta Yagyu Tomokazu Ito Takamitu Yamanaka Takaya Nagai 《无机化学与普通化学杂志》2000,626(1):36-41
Crystal structures of the ambient pressure and temperature phase (phase I) and high pressure phase (phase II) in CuGeO3 were studied by means of the high pressure single‐crystal X‐ray diffraction method in a diamond anvil cell using high power X‐ray generator and imaging plate detector. The pressure dependence of the atomic displacements in the phase I was investigated under the hydrostatic pressure of 0.1 MPa and 2.9 and 3.9 GPa. The lattice is particularly compressive in the b direction. In phase I the rippled layers are formed by the corner‐shared chains of GeO4 tetrahedra and edge‐linked planar CuO4. Major effects of pressure, directly related to the shortening of the b‐axis, consist of an enhanced folding of the rippled layers towards the b‐direction and of a shortening of the weak Cu–O bond. The crystal structure of phase II is monoclinic, a = 4.935(57), b = 6.754(14), c = 6.208(11) Å, β = 92.67(3)°, space group; P21/c. The transition from phase I to II involves a corrugated arrangement of the both cation with some oxygens around the c‐axis. Ge ion at the transition point of 6.4 GPa changes its coordination number from four‐fold to five‐fold, and Cu ion occupies a position of seven‐fold site. The structure of phase II is explained as a slab structure having unique edge‐ and corner‐sharing arrangements of GeO5 and CuO7 polyhedra. The average Ge–O and Cu–O distances in phase II is 1.92 and 2.17 Å, respectively, at 6.5 GPa. 相似文献
318.
319.
320.