全文获取类型
收费全文 | 1050篇 |
免费 | 26篇 |
国内免费 | 7篇 |
专业分类
化学 | 784篇 |
晶体学 | 12篇 |
力学 | 19篇 |
数学 | 91篇 |
物理学 | 177篇 |
出版年
2023年 | 8篇 |
2022年 | 17篇 |
2021年 | 10篇 |
2020年 | 8篇 |
2019年 | 13篇 |
2018年 | 9篇 |
2017年 | 10篇 |
2016年 | 16篇 |
2015年 | 19篇 |
2014年 | 22篇 |
2013年 | 65篇 |
2012年 | 56篇 |
2011年 | 58篇 |
2010年 | 38篇 |
2009年 | 27篇 |
2008年 | 61篇 |
2007年 | 79篇 |
2006年 | 62篇 |
2005年 | 73篇 |
2004年 | 49篇 |
2003年 | 58篇 |
2002年 | 54篇 |
2001年 | 12篇 |
2000年 | 16篇 |
1999年 | 20篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 15篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 22篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 16篇 |
1980年 | 13篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1973年 | 4篇 |
1972年 | 3篇 |
排序方式: 共有1083条查询结果,搜索用时 15 毫秒
31.
32.
Keiichi Kimura Akira Matsui Yoshiaki Inaki Kiichi Takemoto 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(8):1231-1241
Polymerization of acrylonitrile initiated by triazole-copper(II) complexes was studied in dimethylsulfoxide solution. It was found that the polymerization proceeds by a free radical mechanism; however, the complexes can hardly homopolymerize methyl methacrylate and styrene. Ability of the complexes to initiate polymerization seems to depend on the substituents of triazole, the sort of solvents, and the counterions of copper(n) salts. From the data of visible spectroscopy and the spin trapping, the initiation mechanism was discussed in terms of reduction of copper(II) followed by forming active species. 相似文献
33.
34.
Jun TakayamaSeiko Fukuda Yoshiaki SugiharaAkihiko Ishii Juzo Nakayama 《Tetrahedron letters》2003,44(28):5159-5162
Hetero Diels-Alder reactions of 3,4-di-tert-butylthiophene 1-oxide (1) with thioaldehydes and thioketones take place exclusively, except the reaction with thiobenzophenone, at the syn-π-face of 1 with respect to the SO bond. The π-face selectivity was explained in terms of the extent of conformational changes of 1 that are brought about in the process to the transition states. 相似文献
35.
Nomoto A Mitsuoka H Ozeki H Kobuke Y 《Chemical communications (Cambridge, England)》2003,(9):1074-1075
Introducing a porphyrin bearing electron acceptor onto a self-assembled monolayer (SAM) using a supramolecular method to form a hetero-dimer increased the photocurrent value compared with using porphyrin without an electron acceptor. 相似文献
36.
Porphyrin macrocycles composed of five and six units of m-gable imidazolylporphyrinatozinc (1-Zn) were synthesized by self-assembled cyclization followed by ring-closing metathesis linkings. Each porphyrin macrocycle was isolated by GPC chromatography, and their molecular weights were determined by MALDI-TOF mass spectroscopy. These structures represent mimics of light-harvesting complexes in photosynthetic bacteria. [structure: see text] 相似文献
37.
Yoshiaki Hidaka Hiromitsu Masaoka Hidekazu Oshita Takuji Nakamura Koji Tanaka Hiroyuki Kawano 《国际化学动力学杂志》1992,24(10):871-885
The thermal decomposition of vinylacetylene (C4H4) was studied behind reflected shock waves using both a single-pulse method (reaction time between 0.8 and 3.3 ms) and a time-resolved UV-absorption method (230 nm). The studies were done over the temperature range of 1170–1690 K at the total pressure range of 1.3–2.3 atm. The mechanism was used to interpret both the early and late stages of vinylacetylene decomposition at the high temperatures. It was confirmed that C4H4 dissociation proceeded through the following three channels. The rate constant expression of reaction (1) was determined as k1 = 6.3 × 1013 exp(?87.1 kcal/RT) s?1. The rate constants of the succeeding reactions (chain reaction, C4H4 + H → i-C4H3 + H2 and C4H4 + H → C2H2 + C2H3 and decomposition reactions of free radicals, i-C4H3 + M → C4H2 + H + M) were confirmed or estimated. © John Wiley & Sons, Inc. 相似文献
38.
Copper(II) is determined by non-extractive spectrophotometry as a complex of butylene dithiocarbamate formed in situ by reaction between carbon disulfide and pyrrolidine in aqueous Triton X-100 medium. This method is similar to that with butylene dithiocarbamate as starting material in the sense of simplicity, sensitivity, precision and accuracy. Pyrrolidine is the best of seven secondary amines tested in this way for copper determinations. 相似文献
39.
Taichi Mitsumoto Dr. Yuya Ashida Dr. Kazuya Arashiba Dr. Shogo Kuriyama Akihito Egi Prof. Dr. Hiromasa Tanaka Prof. Dr. Kazunari Yoshizawa Prof. Dr. Yoshiaki Nishibayashi 《Angewandte Chemie (International ed. in English)》2023,62(43):e202306631
We newly designed and prepared a novel molybdenum complex bearing a 4-[3,5-bis(trifluoromethyl)phenyl]pyridine-based PNP-type pincer ligand, based on the bond dissociation free energies (BDFEs) of the N−H bonds in molybdenum-imide complexes bearing various substituted pyridine-based PNP-type pincer ligands. The complex worked as an excellent catalyst toward ammonia formation from the reaction of an atmospheric pressure of dinitrogen with samarium diiodide as a reductant and water as a proton source under ambient reaction conditions, where up to 3580 equivalents of ammonia were formed based on the molybdenum atom of the catalyst. The catalytic activity was significantly improved by one order of magnitude larger than that observed when using the complex before modification. 相似文献
40.