全文获取类型
收费全文 | 3586篇 |
免费 | 155篇 |
国内免费 | 11篇 |
专业分类
化学 | 2707篇 |
晶体学 | 30篇 |
力学 | 67篇 |
数学 | 270篇 |
物理学 | 678篇 |
出版年
2023年 | 36篇 |
2022年 | 48篇 |
2021年 | 65篇 |
2020年 | 103篇 |
2019年 | 69篇 |
2018年 | 38篇 |
2017年 | 47篇 |
2016年 | 87篇 |
2015年 | 105篇 |
2014年 | 101篇 |
2013年 | 139篇 |
2012年 | 158篇 |
2011年 | 172篇 |
2010年 | 98篇 |
2009年 | 113篇 |
2008年 | 134篇 |
2007年 | 129篇 |
2006年 | 146篇 |
2005年 | 114篇 |
2004年 | 98篇 |
2003年 | 83篇 |
2002年 | 94篇 |
2001年 | 97篇 |
2000年 | 91篇 |
1999年 | 56篇 |
1998年 | 54篇 |
1997年 | 36篇 |
1996年 | 55篇 |
1995年 | 39篇 |
1994年 | 54篇 |
1993年 | 37篇 |
1992年 | 51篇 |
1991年 | 43篇 |
1990年 | 41篇 |
1989年 | 41篇 |
1988年 | 36篇 |
1987年 | 41篇 |
1986年 | 34篇 |
1985年 | 44篇 |
1984年 | 34篇 |
1983年 | 36篇 |
1982年 | 46篇 |
1981年 | 32篇 |
1979年 | 28篇 |
1978年 | 28篇 |
1977年 | 30篇 |
1976年 | 29篇 |
1975年 | 28篇 |
1973年 | 29篇 |
1967年 | 29篇 |
排序方式: 共有3752条查询结果,搜索用时 11 毫秒
1.
Synthesis and Photophysical Properties of a Sc3N@C80‐Corrole Electron Donor–Acceptor Conjugate 下载免费PDF全文
Bin Liu Hongyun Fang Prof. Xiaofang Li Wenting Cai Lipiao Bao Marc Rudolf Fabian Plass Prof. Louzhen Fan Prof. Xing Lu Prof. Dirk M. Guldi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):746-752
Embedding endohdedral metallofullerenes (EMFs) into electron donor–acceptor systems is still a challenging task owing to their limited quantities and their still largely unexplored chemical properties. In this study, we have performed a 1,3‐dipolar cycloaddition reaction of a corrole‐based precursor with Sc3N@C80 to regioselectively form a [5,6]‐adduct ( 1 ). The successful attachment of the corrole moiety was confirmed by mass spectrometry. In the electronic ground state, absorption spectra suggest sizeable electronic communications between the electron acceptor and the electron donor. Moreover, the addition pattern occurring at a [5,6]‐bond junction is firmly proven by NMR spectroscopy and electrochemical investigations performed with 1 . In the electronically excited state, which is probed in photophysical assays with 1 , a fast electron‐transfer yields the radical ion pair state consisting of the one‐electron‐reduced Sc3N@C80 and of the one‐electron‐oxidized corrole upon its exclusive photoexcitation. As such, our results shed new light on the practical work utilizing EMFs as building blocks in photovoltaics. 相似文献
2.
3.
4.
Summary In this paper a Gauss-Jordan algorithm with column interchanges is presented and analysed. We show that, in contrast with Gaussian elimination, the Gauss-Jordan algorithm has essentially differing properties when using column interchanges instead of row interchanges for improving the numerical stability. For solutions obtained by Gauss-Jordan with column interchanges, a more satisfactory bound for the residual norm can be given. The analysis gives theoretical evidence that the algorithm yields numerical solutions as good as those obtained by Gaussian elimination and that, in most practical situations, the residuals are equally small. This is confirmed by numerical experiments. Moreover, timing experiments on a Cyber 205 vector computer show that the algorithm presented has good vectorisation properties. 相似文献
5.
M. Stangl V. Dittel J. Acker V. Hoffmann W. Gruner S. Strehle K. Wetzig 《Applied Surface Science》2005,252(1):158-161
At room temperature electroplated copper layers exhibit changes in resistivity, residual stress, and microstructure. This process, known as self-annealing, is intimately linked to the release of organic impurities, which stem from the incorporation of organic additives into the Cu layer in the course of the electroplating process. The behavior of these impurities during self-annealing, represented by the carbon content, could be detected by analytical radio frequency glow discharge optical emission spectrometry (GD-OES) and carrier gas hot extraction (CGHE). The precondition of a quantitative determination is a surface cleaning procedure to remove adsorbed organics from the copper surface. It was observed that at first almost all impurities have to leave the Cu metallization before an accelerated abnormal grain growth can start. The small amount of remaining organic species after self-annealing could be quantified by both examination techniques, GD-OES and CGHE. 相似文献
6.
7.
8.
9.
10.
F. Schreiber M. Hoffmann O. von Geisau J. Pelzl 《Applied Physics A: Materials Science & Processing》1993,57(6):545-551
The conventional and photothermally modulated (PM) ferromagnetic resonance (FMR) of magnetostatic modes (MSM) in yttrium iron garnet (YIG) films have been investigated as a function of temperature. Approaching the ferrimagnetic transition at T
c=560 K a strong enhancement of the PM-FMR signal amplitude is observed which is accompanied by a change of the signal shape. The observations are discussed in the framework of a model that takes into account the temperature derivatives of those quantities that contribute to the high-frequency susceptibility. At temperatures still below T
c a paramagnetic line emerges. The MSM disappear in a state of finite magnetization which is explained on the basis of damping of the MSM being important in the vicinity of the magnetic phase transition. Additionally, frequency and power dependent measurements are presented and the imaging ability of PM-FMR is demonstrated. 相似文献