全文获取类型
收费全文 | 1156篇 |
免费 | 42篇 |
国内免费 | 6篇 |
专业分类
化学 | 968篇 |
晶体学 | 4篇 |
力学 | 6篇 |
数学 | 49篇 |
物理学 | 177篇 |
出版年
2023年 | 11篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 24篇 |
2019年 | 17篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 19篇 |
2015年 | 20篇 |
2014年 | 17篇 |
2013年 | 57篇 |
2012年 | 68篇 |
2011年 | 83篇 |
2010年 | 34篇 |
2009年 | 37篇 |
2008年 | 80篇 |
2007年 | 48篇 |
2006年 | 80篇 |
2005年 | 69篇 |
2004年 | 77篇 |
2003年 | 59篇 |
2002年 | 63篇 |
2001年 | 18篇 |
2000年 | 9篇 |
1999年 | 12篇 |
1998年 | 16篇 |
1997年 | 8篇 |
1996年 | 16篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 20篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 16篇 |
1981年 | 13篇 |
1980年 | 9篇 |
1979年 | 16篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 12篇 |
1974年 | 11篇 |
排序方式: 共有1204条查询结果,搜索用时 187 毫秒
941.
Kenji Kawada Akinori Arimura Tatsuo Tsuri Masahiro Fuji Tadafumi Komurasaki Shuji Yonezawa Akira Kugimiya Nobuhiro Haga Susumu Mitsumori Masanao Inagaki Takuji Nakatani Yoshinori Tamura Shozo Takechi Teruhiko Taishi Junji Kishino Mitsuaki Ohtani 《Angewandte Chemie (International ed. in English)》1998,37(7):973-975
Regioselective halogenations and Suzuki reactions ensure proper linkage of the aromatic rings in two total syntheses of terprenin ( 1 ). Both routes make it possible to prepare 1 efficiently and in large quantity. 相似文献
942.
Haruro Ishitani Susumu Komiyama Sh Kobayashi 《Angewandte Chemie (International ed. in English)》1998,37(22):3186-3188
Strecker reactions of aldimines with Bu3SnCN in the presence of the novel chiral zirconium binuclear catalyst 1 provide α-aminonitriles in good yields and with high enantioselectivities. The reaction can be applied to a wide range of substrates. Since both enantiomers of the chiral sources are readily avaibable, both enantiomers of the α-aminonitriles are easily prepared according to this method. L=N-methylimidazole. 相似文献
943.
A homogeneously aligned nematic liquid crystal cell with a hole-patterned electrode and with an indium-tin oxide (ITO-) coated counter-electrode has been prepared. A non-uniform electric field can be produced by the asymmetrical electrode structure. The liquid crystal director can be reoriented by applying a voltage across the electrodes, and this produces an axially symmetrical profile of the refractive index. This liquid crystal cell is expected to have a lens effect and so its optical properties have been investigated. The profile of the output light intensity was measured by using a detecting system with an optical fibre. Some relationships between the lens properties, the diameter of the hole and the thickness of the liquid crystal layer have been examined. The liquid crystal cell becomes a convex (converging) lens with a relatively low voltage. A focal length of several millimetres can be obtained by applying voltages of 3-4 V. As the applied voltage increases, the focal length becomes longer, and the cell changes to a concave (diverging) lens when a high voltage is applied (≳ 20 V). These properties are discussed from the viewpoint of the director orientation effects resulting from the non-uniform electric fields in the cell. 相似文献
944.
945.
946.
947.
948.
Kosuke Ishijima Dr. Susumu Tanaka Prof. Dr. Hiroaki Imoto Prof. Dr. Kensuke Naka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(14):4676-4682
2,3-Diarylbenzo[b]arsoles were synthesized from zirconacycles and diiodophenylarsine. The structural modification to the luminophore was attained through diarylacetylene precursors, Suzuki–Miyaura coupling, and oxidation of the arsenic atom. The emission properties were controlled according to these modifications. The 2,3-diarylbenzo[b]arsoles showed aggregation-induced emission enhancement; the stronger emission was observed in the solid states than in solutions. In addition, Suzuki–Miyaura polycondensation and olefin metathesis polymerization produced main- and side-chain polymers, respectively. The resultant polymers showed different emission behaviors such as aggregation caused quenching and aggregation induced emission enhancement. 相似文献
949.
Dr. Takashi Kajiwara Dr. Miyuki Ikeda Dr. Katsuaki Kobayashi Dr. Masakazu Higuchi Prof. Dr. Koji Tanaka Prof. Dr. Susumu Kitagawa 《化学:亚洲杂志》2021,16(21):3341-3344
To develop an efficient CO2 reduction catalyst, hybridizing a molecular catalyst and a porous coordination polymer (PCP) is a promising strategy because it can combine both advantages of the precise reactivity control of the former and the CO2 adsorption property of the latter. Although several PCP hybrid catalysts have been reported to date, the CO2 sorption behavior and the CO2 reduction reactivity have been investigated separately, and the CO2 enrichment during the catalysis is still unclear. We report CO2 photoreduction under different temperatures and pressures using a PCP-RuII complex hybrid catalyst. The product selectivity (CO or HCOOH) varied depending on the reaction conditions. The altered selectivity could be interpreted in terms of the CO2 capture in the micropores of a PCP. 相似文献
950.
Beom‐Seok Ko Kimio Yoshimura Sinananwanich Warapon Hideyuki Shishitani Susumu Yamaguchi Hirohisa Tanaka Yasunari Maekawa 《Journal of polymer science. Part A, Polymer chemistry》2019,57(4):503-510
To design novel anion‐conducting polymer electrolyte membranes (AEMs), this paper proposes a basicity index (BI) that is defined by the ion‐exchange ratios of AEMs from the OH? to Cl? forms in a neutral aqueous solution as a parameter for Arrhenius basicity (dissociation constant). Using a radiation‐induced graft polymerization technique, three iminium cations are introduced into fluorinated polymer films. The BI of the iminium‐containing AEMs is less than that of a conventional ammonium‐type AEM. The conductivity and water uptake correlate positively with the BI, whereas the thermal and chemical stabilities correlate negatively with the BI. The dependence on the BI stems from the stabilization of the iminium hydroxide in proportion to the basicity of the original diaza‐compounds, resulting in a decrease in conductivity and water uptake with keeping higher thermal and chemical stabilities. Notably, ion conductivity is sufficient and water uptake is less in AEMs with a medium BI. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 503–510 相似文献