全文获取类型
收费全文 | 553篇 |
免费 | 45篇 |
国内免费 | 3篇 |
专业分类
化学 | 486篇 |
晶体学 | 5篇 |
力学 | 3篇 |
数学 | 17篇 |
物理学 | 90篇 |
出版年
2023年 | 6篇 |
2022年 | 10篇 |
2021年 | 9篇 |
2020年 | 14篇 |
2019年 | 14篇 |
2018年 | 17篇 |
2017年 | 4篇 |
2016年 | 19篇 |
2015年 | 26篇 |
2014年 | 22篇 |
2013年 | 38篇 |
2012年 | 43篇 |
2011年 | 63篇 |
2010年 | 23篇 |
2009年 | 33篇 |
2008年 | 28篇 |
2007年 | 25篇 |
2006年 | 29篇 |
2005年 | 22篇 |
2004年 | 22篇 |
2003年 | 25篇 |
2002年 | 10篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1990年 | 3篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 7篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 3篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 3篇 |
1967年 | 3篇 |
排序方式: 共有601条查询结果,搜索用时 15 毫秒
131.
Naoya Ogata Kohei Sanui Fusako Iwaki Atsuko Nomiyama 《Journal of polymer science. Part A, Polymer chemistry》1984,22(3):793-800
Polycondensation of diesters having hydroxyl or pyridine groups was carried out with hexamethylenediamine (HMD) in the presence of (vinyl alcohol/vinyl acetate) copolymers as a matrix polymer. Apparent rates of the polycondensation of dimethyl tartrate (DMT) with HMD increased with increasing contents of PVA units in the copolymers and a strong entanglement between growing polyamide chains and PVA copolymers took place through the adsorption of HMD and DMT on the matrix copolymers. 2,6-Dimethyl pyridine dicarboxylate (2,6-DMP) reacted with HMD in the presence of the PVA copolymers or polysaccharide, while the rate enhancement effect of the matrix polymers was not significantly observed, as in the case of DMT. The effect of the matrix polymers on the polycondensation was discussed in terms of hydrogen bonding interactions. 相似文献
132.
Satoshi Yasuda Guo-Chuang Wu Hozumi Tanaka Kohei Sanui Naoya Ogata 《Journal of polymer science. Part A, Polymer chemistry》1983,21(9):2609-2616
Direct polycondensation reactions of various dicarboxylic acids and diols were carried out at room temperature with triphenylphosphine and polyhalo compounds to obtain polyesters in good yield. Reaction conditions including solvent, temperature, concentration of monomer, amount of reagents, and effect of matrix on direct polycondenation were investigated. A combination of triphenylphosphine and hexachloroethane was found to be satisfactory for the polyester synthesis. The addition of matrix polymers such as poly(4-vinylpyridine) in the reaction system enhanced the direct polycondensation reaction, and a polyester with a solution viscosity of 2.24 was obtained from bisphenol A and isophthalic acid under the optimum condition. 相似文献
133.
134.
135.
136.
Preparation of ureido group bearing polymers and their upper critical solution temperature in water 下载免费PDF全文
Ami Fujihara Kohei Itsuki Naohiko Shimada Atsushi Maruyama Naoya Sagawa Toshiyuki Shikata Shin‐Ichi Yusa 《Journal of polymer science. Part A, Polymer chemistry》2016,54(18):2845-2854
Poly(2‐ureidoethylmethacrylate) (PUEMn) was synthesized via reversible addition‐fragmentation chain transfer (RAFT) radical polymerization and following polymer reaction. We prepared two PUEMn samples with different degrees of polymerization (n = 100 and 49). The polymers exhibited upper critical solution temperature (UCST) in phosphate‐buffered saline (PBS) solution. The phase separation temperature (Tp) in PBS can be controlled ranging from 17 to 55 °C by changing molecular weight of the polymer, polymer concentration, and adding NaCl concentration. The polymers in PBS formed coacervate drops by liquid–liquid phase separations below Tp. Results of the dielectric relaxation measurement, the hydration number per monomeric unit was 5 above Tp. Based on a fluorescence study, the polymer formed slightly hydrophobic environments below Tp. The liquid–liquid phase separation was occurred presumably because of weak hydrophobic interactions and intermolecularly hydrogen bonding interactions between the pendant ureido groups. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2845–2854 相似文献
137.
Ohyama Kaname Oyamada Kana Kishikawa Naoya Arakawa Miyuki Ohba Yoshihito Kamino Masahiro Wada Mitsuhiro Nakashima Kenichiro Kuroda Naotaka 《Chromatographia》2009,70(9-10):1501-1504
A new class of chiral stationary phases (CSP) with peptide chiral selectors was prepared by solid-phase synthesis with a tert-butoxycarbonyl-L-amino acid on silica. The type of amino acid that is favorable for this class of CSP is discussed. Using the CSP with the phenylalanine peptide selector, the effect of peptide length on the enantioselectivity was investigated in normal-phase mode. The applicability of the CSP with a phenylalanine peptide to chiral ligand-exchange chromatography was also examined.
相似文献138.
The laser-induced fragmentation of thin Au and Ag flakes in acetone by 1064-nm nanosecond laser (with the fluence typically ∼2 J/cm2) potentially offers a highly productive pathway to stable metal nanoparticles in liquid. Acetone serves as a superior liquid medium that keeps fine metal nanoparticles free from precipitation even in such concentrated nanoparticle solutions exceeding ∼0.1 M. Thin metal flakes have good capability to absorb the 1064-nm laser energy as efficiently as in the visible region. A part of the thus laser-heated molten flakes explosively split into submicroparticles, and some other significant part directly into fine nanoparticles. Both kinds of product particles have minor absorption cross-sections for subsequent laser pulses at 1064 nm, and thus no longer fragment further. One of the two kinds of Ag flakes studied in this work yielded fine Ag nanoparticles at a remarkable high production rate of 1.1 mg/min for the input laser power of only ∼0.65 W. 相似文献
139.
Tsuchida Shirou Takahashi Rina Yabe Kurumi Hamaue Naoya Aoki Takashi 《Cellulose (London, England)》2022,29(6):3025-3033
Cellulose - A method for the preparation of dialdehyde cellulose disks (DACD) and subsequent diamino cellulose disks (DAmCD) was developed. DACD was prepared by oxidizing filter paper with sodium... 相似文献