全文获取类型
收费全文 | 2912篇 |
免费 | 124篇 |
国内免费 | 17篇 |
专业分类
化学 | 2364篇 |
晶体学 | 23篇 |
力学 | 21篇 |
数学 | 163篇 |
物理学 | 482篇 |
出版年
2023年 | 26篇 |
2022年 | 20篇 |
2021年 | 39篇 |
2020年 | 68篇 |
2019年 | 56篇 |
2018年 | 22篇 |
2017年 | 16篇 |
2016年 | 64篇 |
2015年 | 65篇 |
2014年 | 80篇 |
2013年 | 141篇 |
2012年 | 177篇 |
2011年 | 195篇 |
2010年 | 107篇 |
2009年 | 88篇 |
2008年 | 207篇 |
2007年 | 189篇 |
2006年 | 197篇 |
2005年 | 191篇 |
2004年 | 189篇 |
2003年 | 148篇 |
2002年 | 145篇 |
2001年 | 44篇 |
2000年 | 47篇 |
1999年 | 49篇 |
1998年 | 41篇 |
1997年 | 46篇 |
1996年 | 28篇 |
1995年 | 32篇 |
1994年 | 25篇 |
1993年 | 16篇 |
1992年 | 19篇 |
1991年 | 16篇 |
1990年 | 10篇 |
1989年 | 19篇 |
1988年 | 15篇 |
1987年 | 11篇 |
1985年 | 27篇 |
1984年 | 23篇 |
1983年 | 13篇 |
1982年 | 21篇 |
1981年 | 22篇 |
1980年 | 18篇 |
1979年 | 13篇 |
1978年 | 7篇 |
1977年 | 12篇 |
1976年 | 10篇 |
1974年 | 6篇 |
1973年 | 7篇 |
1972年 | 6篇 |
排序方式: 共有3053条查询结果,搜索用时 15 毫秒
201.
202.
203.
Kenji Kinashi Yuki Kambe Masahiro Misaki Yasuko Koshiba Kenji Ishida Yasukiyo Ueda 《Journal of polymer science. Part A, Polymer chemistry》2012,50(24):5107-5114
Three types of bi‐functionalized copolymers ( P1FAz , P2FAz , and P3FAz ) with different numbers of fluorene units and an azobenzene unit were synthesized and characterized using UV–vis and polarized absorption spectroanalysis. The trans‐cis photoisomerization was conformed under 400 nm light irradiation for all copolymers in chloroform. However, in the film state, only the trans‐cis photoisomerization occurred by mono‐fluorene attached copolymer poly[(9,9‐di‐n‐octylfluorenyl‐2,7‐diyl)‐alt‐4,4′‐azobenzene)] ( P1FAz ). Photo‐induced alignment was achieved using the P1FAz film after irradiation with linear polarized 400 nm light and subsequent annealing at 60 °C. Surface orientation of a spin‐coating film of poly(9,9‐didodecylfluorene) ( F12 ) was achieved using the photo‐induced alignment layer of the P1FAz film after annealing at 90 °C. The photo‐induced alignment layer of P1FAz has potential application to the surface orientation technique for appropriate polymers, which will be useful for the fabrication of optoelectronics devices. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
204.
205.
Utilizing the unique features of the scanning atom probe (SAP) the binding states of the biomolecules, leucine and methionine, are investigated at atomic level. The molecules are mass analyzed by detecting a single atom and/or clustering atoms field evaporated from a specimen surface. Since the field evaporation is a static process, the evaporated clustering atoms are closely related with the binding between atoms forming the molecules. For example, many thiophene radicals are detected when polythiophene is mass analyzed by the SAP. In the present study the specimens are prepared by immersing a micro cotton ball of single walled carbon nanotubes (SWCNT) in the leucine or methionine solution. The mass spectra obtained by analyzing the cotton balls exhibit singly and doubly ionized carbon ions of SWCNT and the characteristic fragments of the molecules, CH3, CHCH3, C4H7, CHNH2 and COOH for leucine and CH3, SCH3, C2H4, C4H7, CHNH2 and COOH for methionine. 相似文献
206.
Masahiro Yamashita Daisuke Kawakami Satoshi Matsunaga Yoshio Nakayama Mari Sasaki Shinya Takaishi Fumiyasu Iwahori Hitoshi Miyasaka Ken‐ichi Sugiura Yoshiki Wada Hiroshi Miyamae Hiroyuki Matsuzaki Hiroshi Okamoto Hisaaki Tanaka Kazuhiro Marumoto Shin‐ichi Kuroda 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2004,116(36):4867-4871
207.
Masahiro Sekiya Takeshi Noro Toshikatsu Koga Shiro L. Saito 《Journal of computational chemistry》2010,31(3):497-499
Developed and reported are compact yet efficient correlating basis sets for the 57La and 89Ac atoms, missing in the literature. Good performance of these correlating sets is exemplified in molecular applications to diatomic oxides and fluorides. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
208.
209.
Dithienylethenes with a novel photochromic performance 总被引:2,自引:0,他引:2
Dithienylethenes with low decoloration quantum yields and thermal reversibility at high temperature above 100 degrees C were prepared. Introduction of bulky alkoxy substituents at 2- and 2'-positions of the thiophene rings strongly suppressed the cycloreversion quantum yields. The quantum yields were lower than 10(-3), and the photogenerated color remained stable enough under room light. On the other hand, the bulky alkoxy substituent decreased the thermal stability of the colored closed-ring isomers at high temperature. The color of the dithienylethene with cyclohexyloxy substituents faded out in less than 1 min at 160 degrees C. 相似文献
210.
Masahiro FujiwaraNaoya Tajima Tatsuro ImakuboMasafumi Tamura Reizo Kato 《Journal of solid state chemistry》2002,168(2):396-407
This article reports preparation, structure, and conducting property of several cation radical salts of organic donors tetramethyltetrathiafulvalene (TMTTF), ethylenedithiotetrathiafulvalene (EDT-TTF), bis(ethylenedithio)tetrathiafulvalene (ET), bis(ethylenedithio)tetraselenafulvalene (BETS) and hexamethylenetetraselenafulvalene (HMTSF) with two novel planar Te-based dianions, TeI42− and Te2I62−. (ET)5Te2I6 1 and (BETS)5Te2I6 2 are isostructural. In these Te2I62− salts, intermolecular short I···I contacts form a supramolecular corrugated anion sheet. Donor arrangement is similar to the θ-type. With lowering temperature, the resistivity of 1 shows a gradual increase followed by a sharp upturn at 110 K. 2 is metallic down to 120 K and shows a gradual increase of the resistivity followed by a clear transition to an insulating state around 60 K. Crystal structure of (ET)4TeI4 3 is based on the “herring bone” arrangement of ET molecules similar to the α-type. 3 shows a semiconductive behavior around room temperature followed by a transition to an insulating state at 210 K. (EDT-TTF)4TeI4 4, a semiconductor, exhibits a unique two-dimensional arrangement of dimerized EDT-TTF molecules. 相似文献