全文获取类型
收费全文 | 212篇 |
免费 | 15篇 |
专业分类
化学 | 160篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 10篇 |
物理学 | 55篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 15篇 |
2020年 | 9篇 |
2019年 | 15篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 13篇 |
2012年 | 13篇 |
2011年 | 18篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 9篇 |
2007年 | 11篇 |
2006年 | 13篇 |
2005年 | 7篇 |
2004年 | 12篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有227条查询结果,搜索用时 15 毫秒
81.
Amphiphilic Organic–Inorganic Hybrid Zeotype Aluminosilicate like a Nanoporous Crystallized Langmuir–Blodgett Film
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Takuji Ikeda Dr. Norihito Hiyoshi Dr. Shun‐ichi Matsuura Dr. Tetsuya Kodaira Takuma Nakaoka Ami Irisa Miki Kawano Dr. Katsutoshi Yamamoto 《Angewandte Chemie (International ed. in English)》2015,54(27):7994-7998
A new organic–inorganic hybrid zeotype compound with amphiphilic one‐dimensional nanopore and aluminosilicate composition was developed. The framework structure is composed of double aluminosilicate layers and 12‐ring nanopores; a hydrophilic layer pillared by Q2 silicon atom species and a lipophilic layer pillared by phenylene groups are alternately stacked, and 12‐ring nanopores perpendicularly penetrate the layers. The framework topology looks similar to that of an AFI‐type zeolite but possesses a quasi‐multidimensional pore structure consisting of a 12‐ring channel and intersecting small pores equivalent to 8‐rings. The hybrid material with alternately laminated lipophilic and hydrophilic nanospaces can be assumed as a crystallized Langmuir–Blodgett film. It demonstrates microporous adsorption for both hydrophilic and lipophilic adsorptives, and its outer surface tightly adsorbs lysozyme whose molecular size is much larger than its micropore opening. Our results suggest the possibility of designing porous adsorbent with high amphipathicity. 相似文献
82.
Dr. Chihiro Maeda Keiji Nagahata Takuma Shirakawa Prof. Tadashi Ema 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):7887-7891
Helical carbazole-based BODIPY analogues were readily synthesized via aza[7]helicenes. The structures of azahelicene-incorporated BF2 dyes were elucidated by x-ray diffraction analysis. DFT calculations revealed that the π-conjugated system expanded from the helicene moiety to the BODIPY framework. The azahelicene-fused boron complexes showed the Cotton effects and the circularly polarized luminescence (CPL) in the visible region. Furthermore, an axially chiral binaphthyl group was attached to the helically chiral dyes, which enhanced the chiroptical properties. 相似文献
83.
The cycloisomerization of 1,4-enyne 1 in the presence of platinum(II) catalyst afforded 1,2,3-trisubstituted 1H-indene 2 and 2' in good to excellent yields. The reaction proceeded through an unprecedented 1,2-alkenyl rearrangement that afforded a novel reaction topology of 1,4-enynes. 相似文献
84.
Takuma KobayashiShuichi Matsumura 《Polymer Degradation and Stability》2011,96(12):2071-2079
Novel biodegradable and biobased thermoplastic elastomers, poly[dodecanolide-12-hydroxystearate (12HS)], poly(pentadecanolide-12HS) and poly(hexadecanolide-12HS) with Mws of 140,000-290,000 g mol−1 were prepared by the enzymatic copolymerization of a macrolide as the hard segment and methyl 12HS as the soft segment. Their thermal properties, such as Tm and Tc, were measured by DSC. Physicochemical and mechanical properties, such as crystallinity, were also measured. The polymer structures were analyzed with respect to the sequence of the two monomers by 1H NMR spectroscopy using an europium shift reagent. The randomness of the two monomer units in the polymer chain increased with the polymerization time. Both Young’s modulus and tensile strength decreased with increasing 12HS content in the copolymer. In contrast, elongation at break increased with increasing 12HS content, thus demonstrating the copolymers’ elastomeric properties. These copolymers showed biodegradabilities by activated sludge, which also increased with increasing 12HS content. 相似文献
85.
Torigoe H Rahman SM Takuma H Sato N Imanishi T Obika S Sasaki K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(9):2742-2751
Due to the instability of pyrimidine motif triplex DNA at physiological pH, triplex stabilization at physiological pH is crucial in improving its potential in various triplex-formation-based strategies in vivo, such as gene expression regulation, genomic DNA mapping, and gene-targeted mutagenesis. To this end, we investigated the thermodynamic and kinetic effects of our previously reported chemical modification, 2'-O,4'-C-aminomethylene-bridged nucleic acid (2',4'-BNA(NC)) modification of triplex-forming oligonucleotide (TFO), on triplex formation at physiological pH. The thermodynamic analyses indicated that the 2',4'-BNA(NC) modification of TFO increased the binding constant of the triplex formation at physiological pH by more than 10-fold. The number and position of the 2',4'-BNA(NC) modification in TFO did not significantly affect the magnitude of the increase in the binding constant. The consideration of the observed thermodynamic parameters suggested that the increased rigidity and the increased degree of hydration of the 2',4'-BNA(NC)-modified TFO in the free state relative to the unmodified TFO may enable the significant increase in the binding constant. Kinetic data demonstrated that the observed increase in the binding constant by the 2',4'-BNA(NC) modification resulted mainly from the considerable decrease in the dissociation rate constant. The TFO stability in human serum showed that the 2',4'-BNA(NC) modification significantly increased the nuclease resistance of TFO. Our results support the idea that the 2',4'-BNA(NC) modification of TFO could be a key chemical modification to achieve higher binding affinity and higher nuclease resistance in the triplex formation under physiological conditions, and may lead to progress in various triplex-formation-based strategies in vivo. 相似文献
86.
Efficient luminescence from a copper(I) complex doped in organic light-emitting diodes by suppressing C-H vibrational quenching 总被引:1,自引:0,他引:1
Wada A Zhang Q Yasuda T Takasu I Enomoto S Adachi C 《Chemical communications (Cambridge, England)》2012,48(43):5340-5342
Efficient luminescence was realized by suppressing not only excited-state distortion but also C-H vibrational quenching in a Cu complex. Organic light-emitting diodes containing the Cu complex as an emitting dopant exhibited a maximum external quantum efficiency of 7.4%. 相似文献
87.
Degawa T Shimma S Toyoda M 《European journal of mass spectrometry (Chichester, England)》2012,18(4):345-348
A peptide containing a single disulfide bond was sequenced using high-energy collision-induced dissociation (HE-CID) in conjunction with a high mass resolution time-of-flight tandem mass spectrometer equipped with a matrix-assisted laser desorption/ionization source. This mass spectrometer, which has spiral ion trajectory, allowed both high mass resolution and high precursor ion selectivity. It is difficult to obtain sufficient product ions from peptides containing disulfide bonds using HE-CID due to the single collision in the gas phase. To compensate for insufficient dissociation, the disulfide bond was cleaved via an in-source reduction process using 1,5-diaminonaphthalene, a reducing matrix. After applying the reduction in the ionization, subsequent sequencing using HE-CID provided the detailed structural information of the peptide containing the single disulfide bond. 相似文献
88.
Takuma Takemura Ichiro Hayakawa Emi Fukasawa Tetsuya Sengoku Hideo Kigoshi 《Tetrahedron》2012,68(32):6477-6484
The diastereoselective aldol-type reaction of a γ-pyrone via a sodium anion has been developed. This reaction is useful for synthesizing γ-pyrone-containing natural products. Also, we applied the Mukaiyama aldol-type reaction of silyl enol ether of γ-pyrone by using TiCl4. This Mukaiyama aldol-type reaction of γ-pyrone indicated higher anti-aldol selectivity than the aldol-type reaction of a γ-pyrone with NaHMDS. 相似文献
89.
N Sakai T Miyazaki T Sakamoto T Yatsuda T Moriya R Ikeda T Konakahara 《Organic letters》2012,14(17):4366-4369
Direct thioetherification from a variety of aromatic carboxylic acids and thiols using a reducing system combined with InBr(3) and 1,1,3,3-teramethyldisiloxane (TMDS) in a one-pot procedure is demonstrated. It was also found that a system combined with InI(3) and TMDS underwent thioetherification of aliphatic carboxylic acids with thiols. 相似文献
90.
Takuma Tsubusaki 《Tetrahedron》2009,65(45):9448-8114
The 4,4-bis(ethoxycarbonyl)-3,4-dihydro-2(1H)-quinolinones 2 were easily synthesized by the oxidative 6-endo-trig cyclization of 2-[2-(N-arylamino)-2-oxoethyl]malonates 1 with manganese(III) acetate in good to excellent yields. The same reaction of N-(2,4-dimethoxyphenyl)-substituted malonate 1t exclusively produced the 5-exo-cyclized 4,4-bis(ethoxycarbonyl)-1-azaspiro[4,5]deca-6,9-diene-2,8-dione 5t instead of the corresponding dihydroquinolinone. The regioselectivity during the cyclization could be explained by the difference in the activation energy of the transition state of the 6-endo/5-exo cyclization. 相似文献