全文获取类型
收费全文 | 1263篇 |
免费 | 132篇 |
国内免费 | 151篇 |
专业分类
化学 | 818篇 |
晶体学 | 13篇 |
力学 | 153篇 |
综合类 | 16篇 |
数学 | 114篇 |
物理学 | 432篇 |
出版年
2024年 | 3篇 |
2023年 | 20篇 |
2022年 | 41篇 |
2021年 | 49篇 |
2020年 | 44篇 |
2019年 | 43篇 |
2018年 | 38篇 |
2017年 | 35篇 |
2016年 | 58篇 |
2015年 | 55篇 |
2014年 | 81篇 |
2013年 | 78篇 |
2012年 | 124篇 |
2011年 | 119篇 |
2010年 | 88篇 |
2009年 | 83篇 |
2008年 | 85篇 |
2007年 | 82篇 |
2006年 | 88篇 |
2005年 | 62篇 |
2004年 | 50篇 |
2003年 | 25篇 |
2002年 | 20篇 |
2001年 | 19篇 |
2000年 | 17篇 |
1999年 | 42篇 |
1998年 | 21篇 |
1997年 | 12篇 |
1996年 | 11篇 |
1995年 | 11篇 |
1994年 | 7篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有1546条查询结果,搜索用时 593 毫秒
941.
The tetracoordinated lanthanide amides [(Me3Si)2N]3Ln(µ‐Cl)Li(THF)3 were found to serve as highly active catalysts for the phospho‐Aldol‐Brook rearrangement reaction of various dialkyl phosphites and isatins. The reactions produced dialkyl 2‐oxoindolin‐3‐yl phosphates in good to excellent yields in the presence of 1 mol% [(Me3Si)2N]3La(µ‐Cl)Li(THF)3 at room temperature within 5 min. A mechanism for this highly efficient process was proposed. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:449–456, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21036 相似文献
942.
Huang Y Song F Wang Z Xi P Wu N Wang Z Lan J You J 《Chemical communications (Cambridge, England)》2012,48(23):2864-2866
A Pd/Cu-catalyzed dehydrogenative Heck coupling is established that allows direct alkenylation of various biologically relevant N-heteroarenes with alkenes. The resulting π-extended alkenylated N-heteroarenes exhibit interesting fluorescent properties and have proven to be potentially useful fluorescent probes for bioimaging. 相似文献
943.
Chen G Song F Wang J Yang Z Sun S Fan J Qiang X Wang X Dou B Peng X 《Chemical communications (Cambridge, England)》2012,48(24):2949-2951
A specific ratiometric nanoprobe for hypochlorite was constructed as a paradigm of FRET spectral unmixing. The separation of FRET pairs' emissions reaches 175 nm, which ensures that the FRET probing is more accurate. This new nanoprobe shows high selectivity and potential in biological systems. 相似文献
944.
We develop a simple dry wrapping method to fabricate a tungsten oxide (WO(3))/carbon nanotube (CNT) cable, in which WO(3) layers act as an electrochromic component while aligned CNTs as the core provide mechanical support and an anisotropic, continuous electron transport pathway. Interestingly, the resultant cable material exhibits an obvious gradient electrochromic phenomenon. 相似文献
945.
Yang J Chu S Guo Y Luo L Kong F Wang Y Zou Z 《Chemical communications (Cambridge, England)》2012,48(29):3533-3535
A N-O bond is introduced into hyperbranched polyimide photocatalysts for the first time to change their polarity and modulate electronic structure. Both of the changes help improve the photocatalytic ability of the polyimide. This strategy shows great prospect for synthesizing effective organic photocatalysts. 相似文献
946.
This paper is devoted to studying the dynamical properties of solutions of , where is an integer, and is a transcendental entire function of finite order. We find the lower bound on the radial distribution of Julia sets of provided that and is a solution base of such equations. 相似文献
947.
The authors are concerned with a zero-flux type initial boundary value problem for scalar conservation laws.Firstly,a kinetic formulation of entropy solutions is established.Secondly,by using the kinet... 相似文献
948.
We demonstrate coherent destruction of tunneling (CDT) in optically induced three-dimensional photonic lattices. By fine-tuning the lattice modulation, we show unusual behavior of beam propagation, including light tunneling inhibition, anomalous diffraction, and negative refraction mediated by zero or negative coupling in the waveguide arrays. Image transmission based on CDT is also proposed and demonstrated. Our experimental results are in good agreement with our theoretical analyses. 相似文献
949.
A simple and efficient method for the cis‐selective synthesis of pyrano‐ and furano[3,2‐c]quinolines via gadolinium chloride catalyzed one‐pot aza–Diels–Alder reaction is described. Solvent conditions played a major role in affecting the diastereoselectivity of the products. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:351–354, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20612 相似文献
950.
Zhigang Lian 《Applied Mathematical Modelling》2010,34(11):3518-3526
The performance of a scheduling system, in practice, is not evaluated to satisfy a single objective, but to obtain a trade-off schedule regarding multiple objectives. Therefore, in this research, I make use of multiple objective decision-making method, a global criterion approach, to develop a multi-objective scheduling problem model with different due-dates on parallel machines processes, in which consider three performance measures, namely minimum run time of every machine, earlierness time (no tardiness) and process time of every job, simultaneously. According to this special multi-objective scheduling problem, the method of reverse order drawing GATT will be proposed, at the same time, bring forward a united search particle swarm optimization algorithm (USPSOA) solves this multi-objective scheduling problem. The validity and adaptability of the USPSOA is investigated through experimental results. 相似文献