全文获取类型
收费全文 | 31414篇 |
免费 | 795篇 |
国内免费 | 228篇 |
专业分类
化学 | 20980篇 |
晶体学 | 203篇 |
力学 | 731篇 |
数学 | 6029篇 |
物理学 | 4494篇 |
出版年
2022年 | 226篇 |
2021年 | 301篇 |
2020年 | 366篇 |
2019年 | 376篇 |
2018年 | 312篇 |
2017年 | 243篇 |
2016年 | 611篇 |
2015年 | 551篇 |
2014年 | 608篇 |
2013年 | 1685篇 |
2012年 | 1448篇 |
2011年 | 1774篇 |
2010年 | 950篇 |
2009年 | 896篇 |
2008年 | 1562篇 |
2007年 | 1585篇 |
2006年 | 1625篇 |
2005年 | 1557篇 |
2004年 | 1359篇 |
2003年 | 1168篇 |
2002年 | 1088篇 |
2001年 | 434篇 |
2000年 | 351篇 |
1999年 | 333篇 |
1998年 | 379篇 |
1997年 | 406篇 |
1996年 | 496篇 |
1995年 | 326篇 |
1994年 | 361篇 |
1993年 | 335篇 |
1992年 | 321篇 |
1991年 | 316篇 |
1990年 | 257篇 |
1989年 | 291篇 |
1988年 | 294篇 |
1987年 | 266篇 |
1986年 | 252篇 |
1985年 | 392篇 |
1984年 | 449篇 |
1983年 | 303篇 |
1982年 | 454篇 |
1981年 | 451篇 |
1980年 | 440篇 |
1979年 | 409篇 |
1978年 | 425篇 |
1977年 | 369篇 |
1976年 | 366篇 |
1975年 | 349篇 |
1974年 | 337篇 |
1973年 | 322篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
5.
Robert G. W. Anderson 《Ambix》2015,62(4):333-344
Following colonisation of South America by the Spanish, many new naturally occurring substances were sent to Europe. One of these was the silvery, unreactive metal, platinum, discovered in New Grenada in the mid-eighteenth century. It was often found in granular form, associated with gold, and the challenge to chemists was to refine it, produce it as wire or sheet, and determine its chemical properties. This interested the professor of chemistry at the University of Edinburgh, Joseph Black, who was able to obtain samples from London-based Spanish contacts, particularly Ignacio Luzuriaga. This paper examines how Black transmitted his knowledge of the metal to large numbers of students attending his annual course. 相似文献
6.
7.
Physical aging in amorphous poly(ethylene furanoate): Enthalpic recovery,density, and oxygen transport considerations
下载免费PDF全文
![点击此处可从《Journal of Polymer Science.Polymer Physics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Steven K. Burgess Christopher R. Mubarak Robert M. Kriegel William J. Koros 《Journal of Polymer Science.Polymer Physics》2015,53(6):389-399
The current work utilizes three separate techniques to study the physical aging process in amorphous poly(ethylene furanoate) (PEF), which is a recently introduced engineering thermoplastic with enhanced properties compared to petroleum‐sourced poly(ethylene terephthalate). Differential scanning calorimetry aging experiments were conducted at multiple aging temperatures and times, and the resultant enthalpic recovery values compared to the theoretical maximum enthalpy loss evaluated from calculations involving extrapolation of the equilibrium liquid line. Density measurements reveal densification of the matrix for the aged versus unaged samples, and provide an estimate for the reduction in free volume for the aged samples. Complementary oxygen permeation and pressure‐decay sorption experiments provide independent verification of the free volume reduction mechanism for physical aging in glassy polymers. The current work provides the first detailed aging study for PEF. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 389–399 相似文献
8.
9.
Transition Metal Chemistry - (η5-Dp)Ru(PPh3)2H (Dp?=?C8H9?, 1,2-dihydropentalenyl) was synthesized in 90% yield by reaction of (η5-Dp)Ru(PPh3)2Cl with sodium formate.... 相似文献
10.