全文获取类型
收费全文 | 173篇 |
免费 | 5篇 |
专业分类
化学 | 130篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 2篇 |
物理学 | 43篇 |
出版年
2023年 | 1篇 |
2021年 | 5篇 |
2020年 | 8篇 |
2019年 | 5篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 11篇 |
2012年 | 11篇 |
2011年 | 9篇 |
2010年 | 7篇 |
2009年 | 11篇 |
2008年 | 15篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 10篇 |
2004年 | 12篇 |
2003年 | 9篇 |
2002年 | 3篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1987年 | 4篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有178条查询结果,搜索用时 171 毫秒
101.
Prof. Dr. Keiichi Hirano Kensuke Morimoto Shota Fujioka Prof. Dr. Kazunori Miyamoto Dr. Atsuya Muranaka Prof. Dr. Masanobu Uchiyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(48):21632-21637
1-Boraphenalenes, a class of boron-doped polyaromatic hydrocarbons, were synthesized by nucleophilic diboration reaction of alkynes. Activation of diboron reagents with a highly basic sp2-carbanion results in very fast successive C−B bond formations to construct the boracycle. This methodology is characterized by high chemoselectivity, affording a wide variety of 1-boraphenarenes with diverse polar substituents. The endocyclic boron can be arylated conveniently in one pot, and the peripheral boron is available for various chemical transformations. Highly diastereoselective diboration gives pseudo-enantio-enriched boraphenarene, which emits circularly polarized fluorescence (CPL). 相似文献
102.
Atsuya Yaguchi Prof. Hirotsugu Hiramatsu Atsuya Ishida Dr. Mio Oshikawa Prof. Itsuki Ajioka Prof. Takahiro Muraoka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(36):9295-9301
Amphiphilic peptides bearing terminal alkyl tails form supramolecular nanofibers that are increasingly used as biomaterials with multiple functionalities. Insertion of alkylene chains in peptides can be designed as another type of amphiphilic peptide, yet the influence of the internal alkylene chains on self-assembly and biological properties remains poorly defined. Unlike the terminal alkyl tails, the internal alkylene chains can affect not only the hydrophobicity but also the flexibility and packing of the peptides. Herein, we demonstrate the supramolecular and biological effects of the central alkylene chain length inserted in a peptide. Insertion of the alkylene chain at the center of the peptide allowed for strengthened β-sheet hydrogen bonds and modulation of the packing order, and consequently the amphiphilic peptide bearing C2 alkylene chain formed a hydrogel with the highest stiffness. Interestingly, the amphiphilic peptides bearing internal alkylene chains longer than C2 showed a diminished cell-adhesive property. This study offers a novel molecular design to tune mechanical and biological properties of peptide materials. 相似文献
103.
104.
Yasuo Iida Judy Lee Teruyuki Kozuka Kyuichi Yasui Atsuya Towata Toru Tuziuti 《Ultrasonics sonochemistry》2009,16(4):519-524
To understand the behaviour of systems containing clouds of bubbles (multibubble system) in real sonochemical reactors, a new diagnosis method, i.e., optical cavitation probe (OCP), has been proposed. When a laser beam is introduced into the cavitation bubble cloud, the scattered light intensity changes by the collective oscillation of cavitation bubbles. The frequency domain spectrum of the scattered light contains rich information on the cavitation bubble clouds, comparable with the acoustic emission spectra detected by a hydrophone. The significant merits of OCP, such as capability for spatially resolved, non-invasive measurement of the cavitation bubble clouds, robustness even in a violent cavitation field have been experimentally demonstrated. 相似文献
105.
Nagao Kobayashi Prof. Dr. Fumiko Narita Kazuyuki Ishii Prof. Dr. Atsuya Muranaka Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(39):10173-10181
Oxovanadium(IV) phthalocyanines (VOPcs) with a single‐handed rotation have been prepared, and their right‐ and left‐handed enantiomers resolved on a chiral HPLC column. These enantiomers gave circular dichroism (CD) spectra of opposite signs; the correlation between the CD sign and conformation was obtained by time‐dependent density functional theory (TDDFT) calculations: an enantiomer showing a negative sign in the Q band was suggested to be the right‐handed conformer viewing from the axial oxygen side, whereas that giving a positive CD sign was assigned to the left‐handed conformer. Although silicon phthalocyanines (SiPcs) with two different alkoxy axial ligands have been resolved similarly, the absence of a meaningful CD difference probably reflects the flat character of the SiPc plane compared to the VOPc plane. Changes in the Q‐band CD, depending on the relative orientation of the peripheral substituents, have been worked out theoretically and the origin of the chiroptical properties is discussed. 相似文献
106.
107.
Prof. Dr. Masaya Nakajima Sho Nagasawa Koki Matsumoto Takahito Kuribara Dr. Atsuya Muranaka Prof. Dr. Masanobu Uchiyama Prof. Dr. Tetsuhiro Nemoto 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(17):6914-6919
According to the Grotthuss–Draper law, light must be absorbed by a substrate to initiate a photoreaction. There have been several reports, however, on the promotion of photoreactions using hypervalent iodine during irradiation with light from a non-absorbing region. This contradiction gave rise to a mystery regarding photoreactions involving hypervalent iodine. We demonstrated that the photoactivation of hypervalent iodine with light from the apparently non-absorbing region proceeds via a direct S0→Tn transition, which has been considered a forbidden process. Spectroscopic, computational, and synthetic experimental results support this conclusion. Moreover, the photoactivation mode could be extended to monovalent iodine and bromine, as well as bismuth(III)-containing molecules, providing new possibilities for studying photoreactions that involve heavy-atom-containing molecules. 相似文献
108.
Sivakumar M Towata A Yasui K Tuziuti T Kozuka T Iida Y Maiorov MM Blums E Bhattacharya D Sivakumar N Ashok M 《Ultrasonics sonochemistry》2012,19(3):652-658
In the present investigation, synthesis of manganese zinc ferrite (Mn0.5Zn0.5Fe2O4) nanoparticles with narrow size distribution have been prepared using ultrasound assisted emulsion (consisting of rapeseed oil as an oil phase and aqueous solution of Mn2+, Zn2+ and Fe2+ acetates) and evaporation processes. The as-prepared ferrite was nanocrystalline. In order to remove the small amount of oil present on the surface of the ferrite, it was subjected to heat treatment at 300 °C for 3 h. Both the as-prepared and heat treated ferrites have been characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), TGA/DTA, transmission electron microscopy (TEM) and energy dispersion X-ray spectroscopy (EDS) techniques. As-prepared ferrite is of 20 nm, whereas the heat treated ferrite shows the size of 33 nm. In addition, magnetic properties of the as-prepared as well as the heat treated ferrites have also been carried out and the results of which show that the spontaneous magnetization (σs) of the heat treated sample (24.1 emu/g) is significantly higher than that of the as-synthesized sample (1.81 emu/g). The key features of this method are avoiding (a) the cumbersome conditions that exist in the conventional methods; (b) usage of necessary additive components (stabilizers or surfactants, precipitants) and (c) calcination requirements. In addition, rapeseed oil as an oil phase has been used for the first time, replacing the toxic and troublesome organic nonpolar solvents. As a whole, this simple straightforward sonochemical approach results in more phase pure system with improved magnetization. 相似文献
109.
S. Momota M. Mihara D. Nishimura M. Fukuda Y. Kamisho M. Wakabayashi K. Matsuta S. Suzuki M. Nagashima Shengyun Zhu Daqing Yuan Yongnan Zheng Zuo Yi Ping Fan T. Izumikawa A. Kitagawa S. Sato M. Kanazawa M. Torikoshi T. Minamisono Y. Nakamura K. Tashiro A. Honma N. Yoshida H. Shirai T. Ohtsubo T. Nagatomo H. Uenishi K. Iwamoto M. Yaguchi T. Ogura T. Ito K. Yamamura Y. Ichikawa Y. Nojiri J. R. Alonso T. J. M. Symons 《Hyperfine Interactions》2013,218(1-3):53-58
Hyperfine interactions were studied in the intermetallic compound GdRh2Si2 by perturbed angular correlation (PAC) technique using 181Hf(181Ta) probe nuclei. The measurements were performed in the temperature range 15–285 K. The PAC spectra above the antiferromagnetic ordering temperature of the GdRh2Si2 compound (T N ~ 106 K), were analyzed using a model that included only electric quadrupole interactions. The observed major fraction was assigned to the 181Hf(181Ta) probe substituting the Gd atoms. The PAC spectra below Néel temperature were analyzed using combined electric quadrupole and magnetic dipole interactions. The Bhf value at Gd, measured at 15 K was found to be 1.4(1) T which, is smaller, when compared with the values obtained in this compound using other nuclear probes, 155Gd (Bhf ~ 30 T) and 140Ce (Bhf ~ 26 T). The present result using 181Hf(181Ta) probe is quite interesting since it shows that the contribution to Bhf at Gd due the host is smaller than other components which contribute to the hyperfine field. The temperature dependence of Bhf shows an anomalous behavior. 相似文献
110.
Matsushita O Derkacheva VM Muranaka A Shimizu S Uchiyama M Luk'yanets EA Kobayashi N 《Journal of the American Chemical Society》2012,134(7):3411-3418
Expanded phthalocyanine (Pc) congeners with two Mo or W central metal ions and four isoindole ring moieties have been synthesized using normal Pc formation conditions in the presence of urea. The products have been characterized by electrochemistry; mass spectrometry (MS); IR, electron paramagnetic resonance (EPR), NMR, electronic absorption, and magnetic circular dichroism (MCD) spectroscopies; and X-ray analysis. The X-ray structures have rectangular C(2v) symmetry and provide evidence that the central Mo atoms are linked by a single bond and coordinated by two isoindole nitrogen atoms and two nitrogen atoms from the amine moieties. The electronic absorption bands extend into the 1200-1500 nm region. This can be explained using Gouterman's four-orbital theory. The experimental NMR data and theoretical calculations provide evidence for a heteroaromatic 22-π-electron conjugation system for the ring-expanded Pc system, which satisfies Hückel's (4n + 2)π aromaticity. 相似文献