全文获取类型
收费全文 | 1050篇 |
免费 | 35篇 |
国内免费 | 2篇 |
专业分类
化学 | 802篇 |
晶体学 | 12篇 |
力学 | 4篇 |
数学 | 64篇 |
物理学 | 205篇 |
出版年
2022年 | 7篇 |
2021年 | 22篇 |
2020年 | 9篇 |
2019年 | 19篇 |
2018年 | 16篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 20篇 |
2014年 | 32篇 |
2013年 | 52篇 |
2012年 | 70篇 |
2011年 | 82篇 |
2010年 | 42篇 |
2009年 | 41篇 |
2008年 | 62篇 |
2007年 | 75篇 |
2006年 | 61篇 |
2005年 | 74篇 |
2004年 | 69篇 |
2003年 | 70篇 |
2002年 | 42篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1997年 | 11篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 10篇 |
1986年 | 3篇 |
1985年 | 17篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有1087条查询结果,搜索用时 27 毫秒
1.
Tanguy Jousselin-Oba Masashi Mamada Atsushi Okazawa Jrome Marrot Takayuki Ishida Chihaya Adachi Abderrahim Yassar Michel Frigoli 《Chemical science》2020,11(44):12194
Biradicaloid compounds with an open-shell ground state have been the subject of intense research in the past decade. Although diindenoacenes are one of the most developed families, only a few examples have been reported as active layers in organic field-effect transistors (OFETs) with a charge mobility of around 10−3 cm2 V−1 s−1 due to a steric disadvantage of the mesityl group to kinetically stabilize compounds. Herein, we disclose our efforts to improve the charge transport of the diindenoacene family based on hexahydro-diindenopyrene (HDIP) derivatives with different annelation modes for which the most reactive position has been functionalized with (triisopropylsilyl)ethynyl (TIPS) groups. All the HDIP derivatives show remarkably higher stability than that of TIPS-pentacene, enduring for 2 days to more than 30 days, which depends on the oxidation potential, the contribution of the singlet biradical form in the ground state and the annelation mode. The annelation mode affects not only the band gap and the biradical character (y0) but also the value of the singlet–triplet energy gap (ΔES–T) that does not follow the reverse trend of y0. A method based on comparison between experimental and theoretical bond lengths has been disclosed to estimate y0 and shows that y0 computed at the projected unrestricted Hartree–Fock (PUHF) level is the most relevant among those reported by all other methods. Thanks to their high stability, thin-film OFETs were successfully fabricated. Well balanced ambipolar transport was obtained in the order of 10−3 cm2 V−1 s−1 in the bottom-gate/top-contact configuration, and unipolar transport in the top-gate/bottom-contact configuration was obtained in the order of 10−1 cm2 V−1 s−1 which is the highest value obtained for biradical compounds with a diindenoacene skeleton.Biradicaloid HDIP derivatives show that the ΔES–T gap does not follow the reverse trend of the biradical character but depends more on the delocalization of the radical centres at the outer rings. 相似文献
2.
3.
Inside Cover: Photoinduced Formation of an Azobenzene‐Based CD‐Active Supramolecular Cyclic Dimer (Chem. Eur. J. 18/2015) 下载免费PDF全文
4.
5.
Hidehisa Kawashima Itsuki Ozawa Masashi Kijima 《Journal of polymer science. Part A, Polymer chemistry》2020,58(13):1747-1756
Rigid and little moldable curdlan, a linear β-1,3-glucan having intra- and interchain hydrogen bonds, was reacted with several alkyl isocyanates, which gave thermoplastic curdlan alkyl carbamates (CrdC) with degree of substitution about 2. The alkyl carbamation at hydroxy groups in the glucan skeleton effectively broke the interchain hydrogen bonds of curdlan and increased flexibility of CrdC, while the newly formed carbamate moieties could moderately keep the hydrogen bonding ability in CrdC. Elongating the alkyl groups in the carbamate side chains increased solubility in organic solvents and thermoplasticity of CrdC, which enabled to make homogeneous and free-standing films by both methods of solution-casting and hot-pressing. 相似文献
6.
Joji Ohshita Takashi Kai Yohei Adachi Kosuke Yamaji Masashi Nakamura Seiji Watase Shingo Mori Noritsumi Matsuyama 《应用有机金属化学》2020,34(1):e5306
Disilane- and disiloxane-bridged bipyridyls ( DSBPy and DSOBPy ) were prepared and their optical properties were investigated in comparison with those of previously reported monosilane- and monogermane-bridged counterparts. The UV–visible absorption and photoluminescence bands of DSBPy and DSOBPy were blue-shifted as a result of elongation of the bridging units from monosilane and monogermane to disilane and disiloxane, likely due to the enhanced twisting of the bipyridyl units. Phosphorescent complexes DSBPy–Cu and DSOBPy–Cu were prepared by the interaction of DSBPy and DSOBPy with Cu2I2(PPh3)2. X-ray diffraction studies of their single-crystal structures revealed polymeric structures composed of repeat units of DSBPy or DSOBPy and [CuII(PPh3)]2. Organic light-emitting diodes with the ITO/PEDOT:PSS/ DSBPy–Cu or DSOBPy–Cu :PCTSQ/TAZ/Al structure were fabricated to examine the applications of the complexes as electroluminescent materials. The devices emitted yellow light with emission maxima at approximately 600 nm, and maximal luminance reached 120 and 190 cd m−2 for devices based on DSBPy–Cu and DSOBPy–Cu , respectively. The performance of the DSOBPy–Cu -based device was improved by using TAZ as the dopant of the emissive layer, and luminance was increased to 390 cd m−2. 相似文献
7.
Dr. Masashi Hasegawa Chika Hasegawa Yuki Nagaya Prof. Dr. Kazunori Tsubaki Prof. Dr. Yasuhiro Mazaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(59):e202202218
Chiral macrocyclic dimers, trimers, and tetramers composed of paraphenylene and tethered binaphthyl were synthesized, and their molecular structures and chiroptical properties were investigated. X-ray analysis and theoretical calculations revealed that multiple twisted molecular structures – dimers, trimers, and tetramers – adopt figure-of-eight, Möbius triangle, and concave rectangle structures, respectively. These homologues have large ϵ values in their UV-vis absorption spectra because of the π-conjugation of the naphthalene-phenylene-naphthalene frameworks. Owing to the shape-persistent ring structure and tethering with −OCH2CH2O−, high fluorescence quantum yields and a relatively high dissymmetry factor gCPL in circularly polarized luminescence (CPL) spectra were achieved. This results in CPL brightness (BCPL) of over 100, which is greater than that of the conventional organic CPL dye. 相似文献
8.
Yan Binggong Kang Lei Kotobuki Masashi He Linchun Liu Bin Jiang Kaiyong 《Journal of Solid State Electrochemistry》2021,25(2):527-534
Journal of Solid State Electrochemistry - We report effectiveness of dopants selected from group 13, such as B, Ga, and In, on the conductivity of Li1.5Al0.5Ge1.5(PO4)3 (LAGP) that is recognized as... 相似文献
9.
Synthesis,Structure, Optical,and Electrochemical Properties of Triple‐ and Quadruple‐Decker Co‐facial Tetrathiafulvalene Arrays 下载免费PDF全文
Dr. Masashi Hasegawa Dr. Ken‐ichi Nakamura Saki Tokunaga Yumi Baba Ryota Shiba Prof. Dr. Takashi Shirahata Prof. Dr. Yasuhiro Mazaki Prof. Dr. Yohji Misaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(29):10090-10101
Understanding the details of the electronic structure in face‐to‐face arranged tetrathiafulvalenes (TTFs) is very important for the design of supramolecular functional materials and superior conductive organic materials. This article is a comprehensive study of the interactions among columnar stacked TTFs using trimeric (trimer) and tetrameric (tetramer) TTFs linked by alkylenedithio groups (‐S(CH2)nS‐, n=1–4) as models of triple‐ and quadruple‐decker TTF arrays. Single‐crystal X‐ray analyses of neutral trimeric TTFs revealed that the three TTF moieties are oriented in a zigzag arrangement. Cyclic voltammetry measurements (CV) reveal that the trimer and tetramer exhibited diverse reversible redox processes with multi‐electron transfers, depending on the length of the ‐S(CH2)nS‐ units and substituents. The electronic spectra of the radical cations, prepared by electrochemical oxidation, showed charge resonance (CR) bands in the NIR/IR region (1630–1850 nm), attributed to a mixed valence (MV) state of the triple‐ and quadruple‐decker TTF arrays. In the trimeric systems, the dicationic state (+2; 0.66 cation per TTF unit) was found to be a stable state, whereas the monocationic state (+1) was not observed in the electronic spectra. In the tetrameric system, substituent‐dependent redox processes were observed. Moreover, π‐trimers and π‐tetramers, which show a significant Davydov blueshift in the spectra, are formed in the tricationic (trimer) and tetracationic (tetramer) state. In addition, these attractive interactions are strongly dependent on the length of the linkage unit. 相似文献
10.