全文获取类型
收费全文 | 276篇 |
免费 | 14篇 |
国内免费 | 3篇 |
专业分类
化学 | 204篇 |
晶体学 | 3篇 |
力学 | 6篇 |
数学 | 21篇 |
物理学 | 59篇 |
出版年
2022年 | 5篇 |
2021年 | 5篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 8篇 |
2011年 | 12篇 |
2010年 | 3篇 |
2009年 | 10篇 |
2008年 | 10篇 |
2007年 | 13篇 |
2006年 | 11篇 |
2005年 | 19篇 |
2004年 | 10篇 |
2003年 | 11篇 |
2002年 | 21篇 |
2001年 | 12篇 |
2000年 | 6篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1954年 | 1篇 |
1942年 | 1篇 |
排序方式: 共有293条查询结果,搜索用时 953 毫秒
131.
Y. Paul Handa Steeve Lampron Mark L. O'neill 《Journal of Polymer Science.Polymer Physics》1994,32(15):2549-2553
Change in the glass transition temperature, Tg, of poly(2,6-dimethyl phenylene oxide), PPO, due to the dissolved CO2 has been measured as a function of the gas pressure, p, using a high-pressure DSC cell. At 61.2 atm, the highest pressure studied, Tg is depressed by 31.6°C. The depression in Tg is found to be linear with pressure, with dTg/dp of ?0.5°C atm?1. The experimental results are in fair agreement with those calculated from a quasilattice solid-solution model for polymer-diluent systems. The present results, however, differ markedly from a recent investigation on PPO-CO2 system which reported a depression in Tg of 226°C at 60 atm and a dTg/dp of ?3.8°C atm?. © 1994 John Wiley & Sons, Inc. 相似文献
132.
133.
134.
Yasuyuki Kurosu Kiyokatsu Hibi Toru Sasaki Muneo Saito 《Journal of separation science》1991,14(3):200-203
We have investigated the influence of capillary temperature on migration time and peak area and have evaluated different cooling systems. It was found that for applied voltages below 15 kV (i.e. those most frequently used) temperature control effectively improves peak area reproducibility but has less effect on migration time. 相似文献
135.
136.
Kenji Handa 《Probability Theory and Related Fields》2002,122(4):545-566
Fleming–Viot processes with mutation, selection and recombination are studied. Their reversible distributions are shown to
be characterized as quasi-invariant measures with a cocycle given in terms of the mutation operator, the selection intensity,
and the recombination kernel. By using this, we derive not only a necessary and sufficient condition for the Fleming–Viot
process to be reversible, but also identify the reversible distributions in the reversible case.
Received: 18 January 2001 / Revised version: 21 June 2001 / Published online: 22 February 2002 相似文献
137.
Masayoshi Takahashi Yoshitaka Yamamoto A. Victoria Nawaby Y. Paul Handa 《Journal of Polymer Science.Polymer Physics》2003,41(18):2214-2217
Laser Raman spectroscopy, in conjunction with an optical high‐pressure cell, was used to investigate the poly(methyl methacrylate)‐carbon dioxide system. The Raman shifts associated with carbon dioxide molecules in the gas phase and those dissolved in the polymer were used to derive sorption kinetics of carbon dioxide and the carbon dioxide‐induced phase changes in the polymer. Measurements were made in the temperature and pressure ranges in which this system is known to exhibit retrograde vitrification behavior. The Raman results on the sorption kinetics and on the onset of plasticization were in agreement with those obtained by gravimetric and calorimetric techniques, respectively. This technique provides a versatile and rapid way of characterizing polymer‐gas systems and information that so far has been obtainable only through painstaking and time‐consuming techniques. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2214–2217, 2003 相似文献
138.
Jun-ichi Kawakami Koji Nakamoto Shigeru Nuwa Syoji Handa Shokyo Miki 《Tetrahedron letters》2006,47(7):1201-1203
Reformatsky reactions of p-quinones with crystalline reagent (BrZnCH2CO2Et·THF)2 were investigated and took place successfully, providing β-hydroxy esters in high yield. Notably, in the case of 2,6-disubstituted-p-quinones, regioselective Reformatsky reactions occurred to give corresponding β-hydroxy esters in good yields. 相似文献
139.
Handa S Giacalone F Haque SA Palomares E Martín N Durrant JR 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(24):7440-7447
The charge-recombination dynamics of two exTTF-C60 dyads (exTTF = 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene), observed after photoinduced charge separation, are compared in solution and in the solid state. The dyads differ only in the degree of conjugation of the bridge between the donor (exTTF) and the acceptor (C60) moieties. In solution, photoexcitation of the nonconjugated dyad C60-BN-exTTF (1) (BN = 1,1'-binaphthyl) shows slower charge-recombination dynamics compared with the conjugated dyad C60-TVB-exTTF (2) (TVB = bisthienylvinylenebenzene) (lifetimes of 24 and 0.6 micros, respectively), consistent with the expected stronger electronic coupling in the conjugated dyad. However, in solid films, the dynamics are remarkably different, with dyad 2 showing slower recombination dynamics than 1. For dyad 1, recombination dynamics for the solid films are observed to be tenfold faster than in solution, with this acceleration attributed to enhanced electronic coupling between the geminate radical pair in the solid film. In contrast, for dyad 2, the recombination dynamics in the solid film exhibit a lifetime of 7 micros, tenfold slower than that observed for this dyad in solution. These slow recombination dynamics are assigned to the dissociation of the initially formed geminate radical pair to free carriers. Subsequent trapping of the free carriers at film defects results in the observed slow recombination dynamics. It is thus apparent that consideration of solution-phase recombination data is of only limited value in predicting the solid-film behaviour. These results are discussed with reference to the development of organic solar cells based upon molecular donor-acceptor structures. 相似文献
140.
Both diastereoisomers of S-tert-butyl-beta-(trifluoromethyl)isocysteine have been synthesized stereoselectively by the sequential reactions of trifluoroacetimidoyl chloride with the lithium enolate of tert-butyl alpha-tert-butylthioacetate, followed by the diastereoselective reduction of the imino group with sodium borohydride in the presence of zinc(II) or di(ethylene glycol) dimethyl ether, and finally by the deprotection of N-aryl and tert-butyl ester groups. 相似文献