全文获取类型
收费全文 | 252517篇 |
免费 | 2890篇 |
国内免费 | 1140篇 |
专业分类
化学 | 119985篇 |
晶体学 | 3259篇 |
力学 | 14343篇 |
综合类 | 8篇 |
数学 | 49481篇 |
物理学 | 69471篇 |
出版年
2021年 | 1122篇 |
2020年 | 1244篇 |
2019年 | 1239篇 |
2018年 | 11392篇 |
2017年 | 11184篇 |
2016年 | 8376篇 |
2015年 | 2877篇 |
2014年 | 2964篇 |
2013年 | 8305篇 |
2012年 | 10359篇 |
2011年 | 18514篇 |
2010年 | 10584篇 |
2009年 | 11067篇 |
2008年 | 14020篇 |
2007年 | 16097篇 |
2006年 | 7659篇 |
2005年 | 8221篇 |
2004年 | 7703篇 |
2003年 | 7252篇 |
2002年 | 6170篇 |
2001年 | 6332篇 |
2000年 | 4881篇 |
1999年 | 3672篇 |
1998年 | 2850篇 |
1997年 | 2802篇 |
1996年 | 2881篇 |
1995年 | 2453篇 |
1994年 | 2309篇 |
1993年 | 2194篇 |
1992年 | 2447篇 |
1991年 | 2401篇 |
1990年 | 2093篇 |
1989年 | 2092篇 |
1988年 | 2127篇 |
1987年 | 2044篇 |
1986年 | 1966篇 |
1985年 | 2881篇 |
1984年 | 2827篇 |
1983年 | 2268篇 |
1982年 | 2482篇 |
1981年 | 2341篇 |
1980年 | 2298篇 |
1979年 | 2247篇 |
1978年 | 2310篇 |
1977年 | 2248篇 |
1976年 | 2172篇 |
1975年 | 2159篇 |
1974年 | 2056篇 |
1973年 | 2147篇 |
1972年 | 1225篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
12.
13.
Control over Nanostructures and Associated Mesomorphic Properties of Doped Self‐Assembled Triarylamine Liquid Crystals 下载免费PDF全文
Dr. Yuya Domoto Dr. Eric Busseron Prof. Dr. Mounir Maaloum Dr. Emilie Moulin Prof. Dr. Nicolas Giuseppone 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(5):1938-1948
We have synthesized a series of triarylamine‐cored molecules equipped with an adjacent amide moiety and dendritic peripheral tails in a variety of modes. We show by 1H NMR and UV/Vis spectroscopy that their supramolecular self‐assembly can be promoted in solution upon light stimulation and radical initiation. In addition, we have probed their molecular arrangements and mesomorphic properties in the bulk by integrated studies on their film state by using differential scanning calorimetry (DSC), variable‐temperature polarizing optical microscopy (VT‐POM), variable‐temperature X‐ray diffraction (VT‐XRD), and atomic force microscopy (AFM). Differences in the number and the disposition of the peripheral tails significantly affect their mesomorphic properties associated with their lamellar‐ or columnar‐packed nanostructures, which are based on segregated stacks of the triphenylamine cores and the lipophilic/lipophobic periphery. Such structural tuning is of interest for implementation of these soft self‐assemblies as electroactive materials from solution to mesophases. 相似文献
14.
15.
16.
17.
18.
Erosion and sediments transport processes have a great impact on industrial structures and on water quality. Despite its limitations, the Saint‐Venant‐Exner system is still (and for sure for some years) widely used in industrial codes to model the bedload sediment transport. In practice, its numerical resolution is mostly handled by a splitting technique that allows a weak coupling between hydraulic and morphodynamic distinct softwares but may suffer from important stability issues. In recent works, many authors proposed alternative methods based on a strong coupling that cure this problem but are not so trivial to implement in an industrial context. In this work, we then pursue 2 objectives. First, we propose a very simple scheme based on an approximate Riemann solver, respecting the strong coupling framework, and we demonstrate its stability and accuracy through a number of numerical test cases. However, second, we reinterpret our scheme as a splitting technique and we extend the purpose to propose what should be the minimal coupling that ensures the stability of the global numerical process in industrial codes, at least, when dealing with collocated finite volume method. The resulting splitting method is, up to our knowledge, the only one for which stability properties are fully demonstrated. 相似文献
19.
20.