全文获取类型
收费全文 | 347篇 |
免费 | 24篇 |
专业分类
化学 | 310篇 |
晶体学 | 2篇 |
力学 | 5篇 |
数学 | 9篇 |
物理学 | 45篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 14篇 |
2021年 | 14篇 |
2020年 | 16篇 |
2019年 | 11篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 18篇 |
2015年 | 13篇 |
2014年 | 14篇 |
2013年 | 35篇 |
2012年 | 29篇 |
2011年 | 28篇 |
2010年 | 21篇 |
2009年 | 12篇 |
2008年 | 20篇 |
2007年 | 17篇 |
2006年 | 16篇 |
2005年 | 14篇 |
2004年 | 10篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2000年 | 1篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 2篇 |
排序方式: 共有371条查询结果,搜索用时 15 毫秒
201.
Yuya Yamashita Tetsuo Tsuda Masahiko Okada Shouji Iwatsuki 《Journal of polymer science. Part A, Polymer chemistry》1966,4(9):2121-2135
Carefully determined cationic copolymerization parameters of cyclic ethers, formals, and esters are collected. Relative reactivity correlates with basicity and free energy. Further correlations of the copolymerization parameters for styrene, the effect of promoters, and the known mechanism of hydrolysis permitted a decision between the carbonium ion (including acylium ion) or the oxonium ion as the active intermediate of the propagation. Structural features which promote depropagation are identified. Equations describing these possibilities were derived and briefly discussed. Catalyst and solvent effects limited the correlation possibilities. 相似文献
202.
Direct N‐Glycofunctionalization of Amides with Glycosyl Trichloroacetimidate by Thiourea/Halogen Bond Donor Co‐Catalysis 下载免费PDF全文
Dr. Yusuke Kobayashi Yuya Nakatsuji Shanji Li Dr. Seiji Tsuzuki Prof. Dr. Yoshiji Takemoto 《Angewandte Chemie (International ed. in English)》2018,57(14):3646-3650
Using a halogen bond (XB) donor and Schreiner's thiourea as cooperative catalysts, various amides, including the asparagine residues of several peptides, were directly coupled with glycosyl trichloroacetimidates to give unique N‐acylorthoamides in good yields. Synthetic applications of N‐acylorthoamides, including rearrangement to the corresponding β‐N‐glycoside, were also demonstrated. 相似文献
203.
Size‐Dependent Thermochromism through Enhanced Electron–Phonon Coupling in 1 nm Quantum Dots 下载免费PDF全文
Haruna Tamaki Dr. Hiroto Watanabe Sachiko Kamiyama Dr. Yuya Oaki Prof. Dr. Hiroaki Imai 《Angewandte Chemie (International ed. in English)》2014,53(40):10706-10709
1 nm CuO quantum dots (QDs) were produced in size‐controlled super‐micropores of a silica matrix. The reversible color change of the QDs from pale blue to deep green was clearly observed in a wide temperature range from 298 to 673 K. This particular thermochromism is ascribed to an enhanced bandgap shift depending on temperature with a strong electron–phonon coupling in the confined space of the 1 nm QDs. 相似文献
204.
Dr. Yosuke Ashikari Dr. Takashi Tamaki Tomoko Kawaguchi Mai Furusawa Yuya Yonekura Susumu Ishikawa Dr. Yusuke Takahashi Yoko Aizawa Prof. Dr. Aiichiro Nagaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(65):16107-16111
A chemoselectivity switchable microflow reaction was developed to generate reactive and unstable intermediates. The switchable chemoselectivity of this reaction enables a selection for one of two different intermediates, an aryllithium or a benzyl lithium, at will from the same starting material. Starting from bromo-substituted styrenes, the aryllithium intermediates were converted to the substituted styrenes, whereas the benzyl lithium intermediates were engaged in an anionic polymerization. These chemoselectivity-switchable reactions can be integrated to produce polymers that cannot be formed during typical polymerization reactions. 相似文献
205.
Yuya Koda 《manuscripta mathematica》2007,123(3):285-299
We prove that an invariant of closed 3-manifolds, called the block number, which is defined via flow-spines, equals the Heegaard genus, except for S
3 and S
2 × S
1. We also show that the underlying 3-manifold is uniquely determined by a neighborhood of the singularity of a flow-spine.
This allows us to encode a closed 3-manifold by a sequence of signed labeled symbols. The behavior of the encoding under the
connected sum and a criterion for reducibility are studied. 相似文献
206.
Maeda H Kinoshita K Naritani K Bando Y 《Chemical communications (Cambridge, England)》2011,47(29):8241-8243
Pyrrole-based π-conjugated anion-responsive molecules bearing an anionic moiety form self-complementary dimers, which exhibit self-sorting behaviours depending on the substituted positions of anionic sites. 相似文献
207.
Hatanaka T Usuki H Arima J Uesugi Y Yamamoto Y Kumagai Y Yamasato A Mukaihara T 《Applied biochemistry and biotechnology》2011,163(7):836-844
l-Asparaginase (ASNase) has proved its use in medical and food industries. Sequence-based screening showed the thermophilic
Streptomyces strain Streptomyces thermoluteus subsp. fuscus NBRC 14270 (14270 ASNase) to positive against predicted ASNase primary sequences. The 14270 ASNase gene and four l-asparaginase genes from Streptomyces coelicolor, Streptomyces avermitilis, and Streptomyces griseus (SGR ASNase) were expressed in Streptomyces lividans using a hyperexpression vector: pTONA5a. Among those genes, only 14270 ASNase and SGR ASNase were successful for overexpression and detected in culture supernatants
without an artificial signal peptide. Comparison of the two Streptomyces enzymes described above demonstrated that 14270 ASNase was superior to SGR ASNase in terms of optimum temperature, thermal
stability, and pH stability. 相似文献
208.
Yuya Hirokawa Yasuhiro Shibata Takayuki Konya Yuya Koike Toshihiro Nakamura 《X射线光谱测定》2013,42(3):134-140
A method for the quantitative analysis of Co, Ni, Pd, Ag, and Au in the scrapped printed‐circuit‐board ash by X‐ray fluorescence (XRF) spectrometry using loose powder was developed. The printed‐circuit‐board samples were converted to ash pyrolytically in porcelain crucibles by sequential heating using a gas burner and electric furnace, and then were ground with a ball mill. The calibrating standards were prepared by adding the appropriate amounts of NiO powder and aqueous standard solutions containing Co, Pd, Ag, and Au to the base mixtures of Al2O3 (5.0 mass%), SiO2 (49 mass%), CaCO3 (11 mass%), Fe2O3 (3.3 mass%), and CuO (30 mass%) as a matrix. Then, 10 g of the resulting mixtures were dried and homogenized for 90 min with a V‐type mixing machine. Specimens for XRF analysis were prepared from the so‐called loose‐powder method in which powder samples were compacted into a hole (12.0‐mm diameter and 5.0‐mm height) in an acrylic plate and covered with a 6‐µm thickness of polypropylene film. Matrix effects were corrected using the intensity value of Compton scattering for PdKα, AgKα, and AuLβ2, and that of background scattering at 35.8° (2θ) for CoKα and NiKα. The detection limits corresponding to three times the standard deviation of the blank intensity were 2.5–45 µg g?1. The proposed method was validated against the pressed‐powder‐pellet method by comparing the calibration curves. Moreover, the concentrations of Co, Ni, Pd, and Ag determined using the proposed XRF method were approximately the same as those resulting from an atomic‐absorption‐spectrometric analysis. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
209.
Yuya Shinohara Akira Watanabe Hiroyuki Kishimoto Yoshiyuki Amemiya 《Journal of synchrotron radiation》2013,20(5):801-804
Combined X‐ray photon correlation spectroscopy (XPCS) and diffracted X‐ray tracking (DXT) measurements of carbon‐black nanocrystals embedded in styrene–butadiene rubber were performed. From the intensity fluctuation of speckle patterns in a small‐angle scattering region (XPCS), dynamical information relating to the translational motion can be obtained, and the rotational motion is observed through the changes in the positions of DXT diffraction spots. Graphitized carbon‐black nanocrystals in unvulcanized styrene–butadiene rubber showed an apparent discrepancy between their translational and rotational motions; this result seems to support a stress‐relaxation model for the origin of super‐diffusive particle motion that is widely observed in nanocolloidal systems. Combined measurements using these two techniques will give new insights into nanoscopic dynamics, and will be useful as a microrheology technique. 相似文献
210.
Acetylation of substituted α,α′‐benzylidenedimethanols with 10 equivalents of vinyl acetate in the presence of 50 w/w% of porcine pancreas lipase (PPL) type II regiospecifically proceeded to afford only the corresponding E‐monoacetates in excellent yields without Z‐monoacetates, diacetate, or the starting materials. 相似文献