全文获取类型
收费全文 | 94933篇 |
免费 | 3279篇 |
国内免费 | 133篇 |
专业分类
化学 | 58336篇 |
晶体学 | 469篇 |
力学 | 2401篇 |
综合类 | 3篇 |
数学 | 17145篇 |
物理学 | 19991篇 |
出版年
2023年 | 653篇 |
2022年 | 666篇 |
2021年 | 1106篇 |
2020年 | 1325篇 |
2019年 | 1279篇 |
2018年 | 2165篇 |
2017年 | 1763篇 |
2016年 | 3075篇 |
2015年 | 2624篇 |
2014年 | 2677篇 |
2013年 | 5744篇 |
2012年 | 5946篇 |
2011年 | 6021篇 |
2010年 | 3777篇 |
2009年 | 3227篇 |
2008年 | 5242篇 |
2007年 | 5093篇 |
2006年 | 4574篇 |
2005年 | 4401篇 |
2004年 | 3810篇 |
2003年 | 3138篇 |
2002年 | 2732篇 |
2001年 | 1852篇 |
2000年 | 1760篇 |
1999年 | 1241篇 |
1998年 | 958篇 |
1997年 | 842篇 |
1996年 | 1070篇 |
1995年 | 731篇 |
1994年 | 875篇 |
1993年 | 813篇 |
1992年 | 859篇 |
1991年 | 727篇 |
1990年 | 767篇 |
1989年 | 685篇 |
1988年 | 626篇 |
1987年 | 590篇 |
1986年 | 556篇 |
1985年 | 840篇 |
1984年 | 776篇 |
1983年 | 577篇 |
1982年 | 689篇 |
1981年 | 678篇 |
1980年 | 565篇 |
1979年 | 551篇 |
1978年 | 564篇 |
1976年 | 567篇 |
1975年 | 494篇 |
1974年 | 510篇 |
1973年 | 508篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
31.
Functional Carbazole Liquid‐Crystal Block Codendrimers with Optical and Electronic Properties 下载免费PDF全文
Ismael Gracia Beatriz Feringán Prof. José Luis Serrano Dr. Roberto Termine Dr. Attilio Golemme Dr. Ana Omenat Prof. Joaquín Barberá 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(3):1359-1369
The synthesis and characterisation of a family of block codendrimers consisting of highly versatile mesogenic and carbazole‐containing 2,2‐bis(hydroxymethyl)propionic acid (bis‐MPA) dendrons are reported. The liquid‐crystal behaviour was investigated by means of differential scanning calorimetry, polarised‐light optical microscopy and X‐ray diffraction. Depending on the chemical structure of the constituent dendrons, the codendrimers show lamellar or columnar mesophases. On the basis of the experimental results, models both at the molecular level and in the mesophase are proposed. The physical properties of the block codendrimers derived from the presence of the carbazole moiety in their structure were investigated: photoluminescence in solution and in the mesophase, electrochemical behaviour and hole transport. Electrodeposition of carbazole dendrons afforded a globular supramolecular conformation in which the mesogenic molecular side plays a key role. 相似文献
32.
33.
34.
35.
36.
37.
38.
39.
In this paper, we study the local linear convergence properties of a versatile class of Primal–Dual splitting methods for minimizing composite non-smooth convex optimization problems. Under the assumption that the non-smooth components of the problem are partly smooth relative to smooth manifolds, we present a unified local convergence analysis framework for these methods. More precisely, in our framework, we first show that (i) the sequences generated by Primal–Dual splitting methods identify a pair of primal and dual smooth manifolds in a finite number of iterations, and then (ii) enter a local linear convergence regime, which is characterized based on the structure of the underlying active smooth manifolds. We also show how our results for Primal–Dual splitting can be specialized to cover existing ones on Forward–Backward splitting and Douglas–Rachford splitting/ADMM (alternating direction methods of multipliers). Moreover, based on these obtained local convergence analysis result, several practical acceleration techniques are discussed. To exemplify the usefulness of the obtained result, we consider several concrete numerical experiments arising from fields including signal/image processing, inverse problems and machine learning. The demonstration not only verifies the local linear convergence behaviour of Primal–Dual splitting methods, but also the insights on how to accelerate them in practice. 相似文献
40.