全文获取类型
收费全文 | 458篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
化学 | 382篇 |
晶体学 | 3篇 |
力学 | 3篇 |
数学 | 23篇 |
物理学 | 53篇 |
出版年
2021年 | 3篇 |
2017年 | 3篇 |
2015年 | 2篇 |
2014年 | 6篇 |
2013年 | 18篇 |
2012年 | 12篇 |
2011年 | 21篇 |
2010年 | 12篇 |
2009年 | 13篇 |
2008年 | 17篇 |
2007年 | 23篇 |
2006年 | 25篇 |
2005年 | 21篇 |
2004年 | 15篇 |
2003年 | 18篇 |
2002年 | 20篇 |
2001年 | 5篇 |
2000年 | 9篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 14篇 |
1995年 | 8篇 |
1994年 | 3篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 8篇 |
1974年 | 8篇 |
1973年 | 1篇 |
1972年 | 4篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 4篇 |
1967年 | 3篇 |
排序方式: 共有464条查询结果,搜索用时 15 毫秒
161.
162.
Kunieda Haruo 《International Journal of Solids and Structures》1975,11(4):477-492
This paper presents the determination method of flutter critical wind velocity of hanging roofs and curved membrane roofs of which outer surface only is exposed to wind, and some numerical results for fundamental shape of the roofs are illustrated to make clear the influences of curvatures, materials, size factors and prestressing on this critical velocity, and the dynamic behavior of the roofs subjected to wind. The procedure to formulate the governing equations is on the basis of classical flow theory with vorticities in the boundary layer and in the wake from the trailing edge, and the solution is obtained with Galerkin's procedure. 相似文献
163.
Yue-Ping Xiong Haruo Kishimoto Katsuhiko YamajiMasashi Yoshinaga Teruhisa HoritaManuel E. Brito Harumi Yokokawa 《Solid State Ionics》2011,192(1):476-479
The electronic conductivity of pure ceria with two different impurity levels is examined by dc polarization technique based on the Hebb-Wagner ion blocking method. The impurity level for the ceria with 99.999% purity (5N-CeO2) is about 1/100 of that with 99.9% purity (3N-CeO2) as confirmed by the fluorescence intensity of impurities obtained by Raman spectroscopy. The electronic conductivity for the 5N-CeO2 was measured at T = 973 K to 1173 K, and the results are essentially the same as those for the 3N-CeO2. The electronic conductivity increases with decreasing of P(O2) following slope values of − 1/4 to − 1/6. The − 1/4 dependent region becomes narrower for the 5N-CeO2 than that for the 3N-CeO2. For both types of ceria, the P(O2) independent region appears in the same region of higher than 10− 2 and 10− 3 MPa at T = 1073 K and 973 K, respectively. Activation energies for the 5N-CeO2 were 2.2 eV, 2.6 eV and 1.9 eV in P(O2) dependent regions of − 1/6, − 1/4 and 0, respectively. 相似文献
164.
In the previous paper,2 we described the reaction of lithiated ethynyl compounds using butyllithium at -70° with lactones and sugar lactones such as 2,3 : 5, 6-di-o-isopropyl-idene-L-gulonolactone (I) or 2,3-o-isopropylidene-D-ribonolactone (II) to obtain ethynyl lactols. 相似文献
165.
Ying-Duo Gao Hitomi Kumazaki Junko Terai Kanako Chida Haruo Hosoya 《Journal of mathematical chemistry》1993,12(1):279-308
The band structures and density of states of 77 infintely large conjugated hydrocarbon polymer networks are calculated with HMO. A general rule for predicting whether the HOMO-LUMO band gap is zero or non-zero is proposed for an arbitrary hydrocarbon polymer network with periodic structure. The effects of bond alternation and of conjugate branching are discussed. Molecular design of high spin polymer networks is proposed. 相似文献
166.
The macrocyclic spermidine alkaloid, celacinnine, has been synthesized by methods involving successive ring expansion reactions. One route starts with 4-phenyl-2-azetidinone; another, with piperidazine. 相似文献
167.
168.
Development of an efficient photocatalytic system for CO2 reduction using rhenium(I) complexes based on mechanistic studies 总被引:1,自引:0,他引:1
The reaction mechanism of photocatalytic CO2 reduction using rhenium(I) complexes has been investigated by means of a detailed comparison of the photocatalyses of three rhenium(I) complexes, fac-[Re(bpy)(CO)3L] (L = SCN- (1-NCS), Cl- (1-Cl), and CN- (1-CN)). The corresponding one-electron-reduced species (OER) of the complexes play two important roles in the reaction: (a) capturing CO2 after loss of the monodentate ligand (L) and (b) donation of the second electron to CO2 by another OER without loss of L. In the case of 1-NCS, the corresponding OER has both of the capabilities in the photocatalytic reaction, resulting in more efficient CO formation (with a quantum yield of 0.30) than that of 1-Cl (quantum yield of 0.16), for which OER species have too short a lifetime to accumulate during the photocatalytic reaction. On the other hand, 1-CN showed no photocatalytic ability, because the corresponding OER species does not dissociate the CN- ligand. Based on this mechanistic information, the most efficient photocatalytic system was successfully developed using a mixed system with fac-[Re(bpy)(CO)3(CH3CN)]+ and fac-[Re{4,4'-(MeO)2bpy}(CO)3{P(OEt)3}]+, for which the optimized quantum yield for CO formation was 0.59. 相似文献
169.
Photo‐induced Substitutive Introduction of the Aldoxime Functional Group to Carbon Chains: A Formal Formylation of Non‐Acidic C(sp3)−H Bonds 下载免费PDF全文
Prof. Dr. Shin Kamijo Go Takao Kaori Kamijo Masaki Hirota Dr. Keisuke Tao Prof. Dr. Toshihiro Murafuji 《Angewandte Chemie (International ed. in English)》2016,55(33):9695-9699
A photo‐induced substitutive introduction of an aldoxime functional group to carbon chains was achieved using photo‐excited 4‐benzoylpyridine as a C(sp3)?H bond cleaving agent and arylsulfonyl oxime as an aldoxime precursor. The non‐acidic C?H bonds in various substances, including cycloalkanes, ethers, azacycles, and cyclic sulfides, were chemoselectively converted at ambient temperature under neutral conditions. The present transformation is a formal formylation of non‐acidic C(sp3)?H bonds in a single step. 相似文献
170.
The irradiation of the title compounds [(Z)-1] having (S)-(+)-sec-butyl, (−)-mentyl and related chiral auxiliaries in methanol and 1,2-dichloroethane containing 2-(diethylamino)ethanol afforded chiral auxiliary-substituted (4S,5S)-, (4R,5R)-, (4R,5S)- and (4S,5R)-4,5-dihydrooxazole derivatives (2) along with (E)-1. It was found that the photoinduced electron transfer-initiated cyclization of 1 gives either of the two diastereomers for cis-2 and trans-2 in diastereomeric excess whose value varies from 6% to 81% depending on solvent and chiral auxiliary. 相似文献