全文获取类型
收费全文 | 451篇 |
免费 | 34篇 |
国内免费 | 13篇 |
专业分类
化学 | 325篇 |
晶体学 | 9篇 |
力学 | 32篇 |
综合类 | 3篇 |
数学 | 38篇 |
物理学 | 91篇 |
出版年
2024年 | 3篇 |
2022年 | 17篇 |
2021年 | 21篇 |
2020年 | 10篇 |
2019年 | 12篇 |
2018年 | 14篇 |
2017年 | 15篇 |
2016年 | 16篇 |
2015年 | 18篇 |
2014年 | 24篇 |
2013年 | 52篇 |
2012年 | 17篇 |
2011年 | 21篇 |
2010年 | 25篇 |
2009年 | 24篇 |
2008年 | 31篇 |
2007年 | 15篇 |
2006年 | 20篇 |
2005年 | 15篇 |
2004年 | 16篇 |
2003年 | 12篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1940年 | 1篇 |
1939年 | 1篇 |
1937年 | 1篇 |
1936年 | 3篇 |
1935年 | 2篇 |
排序方式: 共有498条查询结果,搜索用时 0 毫秒
491.
492.
T. Hayat I. Naeem M. Ayub A.M. Siddiqui S. Asghar C.M. Khalique 《Nonlinear Analysis: Real World Applications》2009,10(4):2117-2126
We present here the exact solutions for the equations of magnetohydrodynamic (MHD) aligned flow of a second grade fluid. The exact solutions are constructed for steady and unsteady equations by employing inverse method. 相似文献
493.
Three new chromenone glucosides acylated with monoterpene acids, eucamaldusides A ( 1 ), B ( 2 ), and C ( 3 ), were isolated from the leaves of Eucalyptus camaldulensis var. obtusa, together with the five known compounds ursolic acid lactone, obtusilin, β‐sitosterol glucoside, 4‐hydroxybenzoic acid, and cypellocarpin C. The structures of the new compounds were established by exhaustive 1D‐ and 2D‐NMR spectroscopic studies. Their configuration was determined by measuring the [α]D of the known methyl esters of the monoterpene acids obtained by methanolysis of 1 – 3 . 相似文献
494.
Poly(m-toluidine) (PmT), a derivative of polyaniline, has been prepared by chemical oxidation polymerization method. The synthesized PmT powder is blended with plasticized polyvinyl chloride (PVC) to achieve 20 μm thick self-supported films. These films were irradiated with 60 MeV Si5+ ions at three different fluences whose S e (electronic energy loss) value is found to be 1.988×103 KeV/μ m, an order of magnitude larger than 60 MeV C5+ (2.958×102 KeV/μ m). Fourier transform infrared (FTIR), X-ray diffraction (XRD) and ultraviolet-visible (UV) absorption studies of pre- and post-irradiated films of PmT–PVC blends were carried out to study the heavy ion irradiation effects on these polymer blends. An overall change in the structure of the polymer blend has been observed from FTIR studies. UV-visible spectra show a decrease in the optical band gap (E g) and an increase in cluster size with increasing fluence. An effort is made to compare these results with our earlier studies. We found that the variation in S e plays an important role in the structural and optical properties of PmT–PVC blends. 相似文献
495.
496.
Non‐porous P2 glass beads were etched with sodium hydroxide to increase the number of silanol groups that could be used to modify the surface. The etched glass beads were then functionalized with 3‐aminopropyltriethoxysilane (APS) and/or glycidoxypropyltrimethoxysilane (GPS). The surface of the glass beads were further modified with poly(acrylic acid) (PAA) by reacting the carboxyl groups on PAA with the amino groups of the pregrafted APS. The chemical modifications were characterized by FT‐IR spectroscopy, particle size analyzer and tensiometry for contact angle and porosity measurements. Five different molecular weight PAA polymers ranging from 2000 to 3,000,000 were grafted with less than expected increase of grafted PAA with molecular weight. The amount of APS and PAA on the surface was determined from thermogravimetric analysis and elemental analysis data. The surface properties of the surface modified glass beads were determined by measuring water and hexane penetration rate and contact angle. The surface morphology was examined by scanning electron microscopy. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
497.
498.
Tin monoselinide thin films were obtained by solid state reaction in vacuum. They were characterised by X-ray diffraction and subjected to resistivity and optical absorbance measurements. The data were analysed for obtaining activation energy and band gap. The effects of varying deposition parameters were studied. These films are concluded to be superior to those obtained directly from the compound semiconductor. 相似文献