全文获取类型
收费全文 | 22727篇 |
免费 | 778篇 |
国内免费 | 137篇 |
专业分类
化学 | 16172篇 |
晶体学 | 220篇 |
力学 | 480篇 |
综合类 | 1篇 |
数学 | 3377篇 |
物理学 | 3392篇 |
出版年
2022年 | 236篇 |
2021年 | 274篇 |
2020年 | 376篇 |
2019年 | 377篇 |
2018年 | 265篇 |
2017年 | 252篇 |
2016年 | 535篇 |
2015年 | 441篇 |
2014年 | 541篇 |
2013年 | 1115篇 |
2012年 | 1180篇 |
2011年 | 1503篇 |
2010年 | 762篇 |
2009年 | 615篇 |
2008年 | 1189篇 |
2007年 | 1288篇 |
2006年 | 1248篇 |
2005年 | 1186篇 |
2004年 | 1005篇 |
2003年 | 834篇 |
2002年 | 799篇 |
2001年 | 295篇 |
2000年 | 293篇 |
1999年 | 274篇 |
1998年 | 251篇 |
1997年 | 287篇 |
1996年 | 314篇 |
1995年 | 243篇 |
1994年 | 223篇 |
1993年 | 267篇 |
1992年 | 224篇 |
1991年 | 196篇 |
1990年 | 170篇 |
1989年 | 158篇 |
1988年 | 161篇 |
1987年 | 165篇 |
1986年 | 142篇 |
1985年 | 226篇 |
1984年 | 264篇 |
1983年 | 185篇 |
1982年 | 230篇 |
1981年 | 258篇 |
1980年 | 194篇 |
1979年 | 192篇 |
1978年 | 230篇 |
1977年 | 170篇 |
1976年 | 167篇 |
1975年 | 158篇 |
1974年 | 173篇 |
1973年 | 146篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Piotr T. Chruściel Erwann Delay Paul Klinger Andreas Kriegl Peter W. Michor Armin Rainer 《Letters in Mathematical Physics》2018,108(9):2009-2030
We prove existence of large families of solutions of Einstein-complex scalar field equations with a negative cosmological constant, with a stationary or static metric and a time-periodic complex scalar field. 相似文献
993.
994.
995.
996.
997.
998.
999.
Seow Jecg Chin Peter Hornsby Damjan Vengust Dragan Mihailović J. Mitra Paul Dawson Tony McNally 《先进技术聚合物》2012,23(2):149-160
Composites of poly(ε‐caprolactone) (PCL) and molybdenum sulfur iodine (MoSI) nanowires were prepared using twin‐screw extrusion. Extensive microscopic examination of the composites revealed the nanowires were well dispersed in the PCL matrix, although bundles of Mo6S3I6 ropes were evident at higher loadings. Secondary electron imaging (SEI) showed the nanowires had formed an extensive network throughout the PCL matrix, resulting in increased electrical conductivity of PCL, by eight orders of magnitude, and an electrical percolation threshold of 6.5 × 10?3 vol%. Thermal analysis (DSC), WAXD, and hot stage polarized optical microscopy (HSPOM) experiments revealed Mo6S3I6 addition altered PCL crystallization kinetics, nucleation density, and crystalline content. A greater number of smaller spherulites were formed via heterogeneous nucleation. The onset of thermal decomposition (TGA) of PCL decreased by 70°C, a consequence of the thermal degradation of Mo6S3I6 to MoO3, which in turn accelerates the formation of volatile gases during the first stage of PCL decomposition. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
1000.
Noa Lachman Yifat Harel Adam Green Noa Iuster Jean‐Paul Lellouche H. Daniel Wagner 《Journal of Polymer Science.Polymer Physics》2012,50(14):957-962
In this article, Multi‐Walled Carbon Nanotubes (MWCNTs) of varying diameters, both untreated and polycarboxylated, were dispersed at constant weight percentage in an epoxy matrix, and resulting fracture toughnesses (KIc) were measured in each case. We show that changing the MWCNT diameter has two effects on the composite fracture toughness: (i) a small MWCNT diameter enables larger interfacial surface for adhesion maximization, which increases toughness; (ii) at the same time, it limits the available pull‐out energy and reduces the MWCNT ability to homogeneously disperse in the matrix due to this same large active surface: this decreases toughness. Most commercially available MWCNTs have a length range of several μm, thus an optimal diameter exists which depends on MWCNT wall thickness and surface treatment. Such optimal diameter maximizes pull‐out energy and thus composite fracture toughness. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献