全文获取类型
收费全文 | 6121篇 |
免费 | 263篇 |
国内免费 | 34篇 |
专业分类
化学 | 3807篇 |
晶体学 | 30篇 |
力学 | 211篇 |
数学 | 1279篇 |
物理学 | 1091篇 |
出版年
2023年 | 58篇 |
2022年 | 97篇 |
2021年 | 188篇 |
2020年 | 162篇 |
2019年 | 161篇 |
2018年 | 136篇 |
2017年 | 119篇 |
2016年 | 261篇 |
2015年 | 238篇 |
2014年 | 263篇 |
2013年 | 366篇 |
2012年 | 430篇 |
2011年 | 474篇 |
2010年 | 281篇 |
2009年 | 257篇 |
2008年 | 386篇 |
2007年 | 349篇 |
2006年 | 319篇 |
2005年 | 309篇 |
2004年 | 249篇 |
2003年 | 191篇 |
2002年 | 194篇 |
2001年 | 83篇 |
2000年 | 59篇 |
1999年 | 68篇 |
1998年 | 53篇 |
1997年 | 66篇 |
1996年 | 54篇 |
1995年 | 50篇 |
1994年 | 48篇 |
1993年 | 35篇 |
1992年 | 28篇 |
1991年 | 33篇 |
1990年 | 24篇 |
1989年 | 21篇 |
1988年 | 24篇 |
1987年 | 25篇 |
1986年 | 20篇 |
1985年 | 27篇 |
1984年 | 24篇 |
1983年 | 15篇 |
1982年 | 24篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 19篇 |
1978年 | 17篇 |
1977年 | 10篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1973年 | 11篇 |
排序方式: 共有6418条查询结果,搜索用时 31 毫秒
1.
Cardin Pedro Toniol Teixeira Marco Antonio 《Journal of Dynamics and Differential Equations》2022,34(2):775-787
Journal of Dynamics and Differential Equations - In this paper we focus on a class of symmetric vector fields in the context of singularly perturbed fast-slow dynamical systems. Our main question... 相似文献
2.
3.
Application of TiO2-nanotubes/PbO2 as an anode for the electrochemical elimination of Acid Red 1 dye
Santos José Eudes L. de Moura Dayanne Chianca da Silva Djalma Ribeiro Panizza Marco Martínez-Huitle Carlos A. 《Journal of Solid State Electrochemistry》2019,23(2):351-360
Journal of Solid State Electrochemistry - In this study, galvanostatic electrolysis, through the use of the platinum supported on Ti (Ti/Pt) and Ti/TiO2-nanotubes/PbO2 anodes, was conducted in an... 相似文献
4.
It is known that under resonance conditions, a group of strongly interacting bosonic atoms, trapped in a double-well potential, mimics a single particle, performing Rabi oscillations between the wells. By implication, all atoms need to tunnel at roughly the same time, even though the Bose–Hubbard Hamiltonian accounts only for one-atom-at-a-time transfers. The mechanism of this collective behavior is analyzed, the Rabi frequencies in the process are evaluated, and the limitation of this simple picture is discussed. In particular, it is shown that the small rapid oscillations superimposed on the slow Rabi cycle result from splitting the transferred cluster at the sudden onset of tunnelling, and disappear if tunnelling is turned on gradually. 相似文献
5.
6.
Francesco Segatta David M. Rogers Naomi T. Dyer Ellen E. Guest Zhuo Li Hainam Do Artur Nenov Marco Garavelli Jonathan D. Hirst 《Molecules (Basel, Switzerland)》2021,26(2)
A fully quantitative theory of the relationship between protein conformation and optical spectroscopy would facilitate deeper insights into biophysical and simulation studies of protein dynamics and folding. In contrast to intense bands in the far-ultraviolet, near-UV bands are much weaker and have been challenging to compute theoretically. We report some advances in the accuracy of calculations in the near-UV, which were realised through the consideration of the vibrational structure of the electronic transitions of aromatic side chains. 相似文献
7.
Fernando Bento Cunha Karina Torres Pomini Ana Maria de Guzzi Plepis Virgínia da Conceio Amaro Martins Eduardo Gomes Machado Renato de Moraes Marcelo de Azevedo e Souza Munhoz Michela Vanessa Ribeiro Machado Marco Antonio Hungaro Duarte Murilo Priori Alcalde Daniela Vieira Buchaim Rogrio Leone Buchaim Victor Augusto Ramos Fernandes Eliana de Souza Bastos Mazuqueli Pereira Andr Antonio Pelegrine Marcelo Rodrigues da Cunha 《Molecules (Basel, Switzerland)》2021,26(6)
Autologous bone grafts, used mainly in extensive bone loss, are considered the gold standard treatment in regenerative medicine, but still have limitations mainly in relation to the amount of bone available, donor area, morbidity and creation of additional surgical area. This fact encourages tissue engineering in relation to the need to develop new biomaterials, from sources other than the individual himself. Therefore, the present study aimed to investigate the effects of an elastin and collagen matrix on the bone repair process in critical size defects in rat calvaria. The animals (Wistar rats, n = 30) were submitted to a surgical procedure to create the bone defect and were divided into three groups: Control Group (CG, n = 10), defects filled with blood clot; E24/37 Group (E24/37, n = 10), defects filled with bovine elastin matrix hydrolyzed for 24 h at 37 °C and C24/25 Group (C24/25, n = 10), defects filled with porcine collagen matrix hydrolyzed for 24 h at 25 °C. Macroscopic and radiographic analyses demonstrated the absence of inflammatory signs and infection. Microtomographical 2D and 3D images showed centripetal bone growth and restricted margins of the bone defect. Histologically, the images confirmed the pattern of bone deposition at the margins of the remaining bone and without complete closure by bone tissue. In the morphometric analysis, the groups E24/37 and C24/25 (13.68 ± 1.44; 53.20 ± 4.47, respectively) showed statistically significant differences in relation to the CG (5.86 ± 2.87). It was concluded that the matrices used as scaffolds are biocompatible and increase the formation of new bone in a critical size defect, with greater formation in the polymer derived from the intestinal serous layer of porcine origin (C24/25). 相似文献
8.
9.
The presence of copper atoms as continuous networks at the grain boundaries of an aluminium-copper alloy has been considered not preventing the moving of dislocations during creep (or at least partially). The dislocations can bs absorbed by these boundaries and penetrate through them. That leads to changés of shape and structure of grains and also to the sliding of grains against each other. This was deduced from the accelerating increase in the sensitivity of the steady state creep rate to the applied stress of an aluminium 2·8 wt% copper alloy examined at wide range of temperatures (50–350 °C) and applied stresses (7–170 MPa). This rapid increase in the sensitivity parameter of the steady state creep rate occurs in Al-Cu alloys at quite higher ranges of applied stresses and may be attributed mainly to the contribution of the grain boundary movements to the creep strain. 相似文献
10.