全文获取类型
收费全文 | 3000篇 |
免费 | 161篇 |
国内免费 | 26篇 |
专业分类
化学 | 2188篇 |
晶体学 | 16篇 |
力学 | 56篇 |
数学 | 526篇 |
物理学 | 401篇 |
出版年
2023年 | 19篇 |
2022年 | 52篇 |
2021年 | 98篇 |
2020年 | 67篇 |
2019年 | 90篇 |
2018年 | 42篇 |
2017年 | 44篇 |
2016年 | 134篇 |
2015年 | 103篇 |
2014年 | 123篇 |
2013年 | 154篇 |
2012年 | 244篇 |
2011年 | 255篇 |
2010年 | 154篇 |
2009年 | 129篇 |
2008年 | 224篇 |
2007年 | 202篇 |
2006年 | 188篇 |
2005年 | 192篇 |
2004年 | 129篇 |
2003年 | 104篇 |
2002年 | 90篇 |
2001年 | 34篇 |
2000年 | 24篇 |
1999年 | 29篇 |
1998年 | 15篇 |
1997年 | 25篇 |
1996年 | 36篇 |
1995年 | 21篇 |
1994年 | 17篇 |
1993年 | 18篇 |
1992年 | 8篇 |
1991年 | 17篇 |
1990年 | 13篇 |
1989年 | 5篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 9篇 |
1985年 | 14篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1926年 | 1篇 |
排序方式: 共有3187条查询结果,搜索用时 15 毫秒
121.
122.
123.
Javier Pastor 《Annali di Matematica Pura ed Applicata》2012,191(1):167-180
We obtain uniqueness of additive families {A t } t>0 of fractional powers of a multi-valued sectorial linear operator A ?? A 1 in a Banach space, satisfying a certain kind of continuity with respect to the exponent and a spectral property, from uniqueness of the solutions of the second-order incomplete Cauchy problem associated with A. We show the close relationship between the multiplicativity and the uniqueness of fractional powers. 相似文献
124.
Recent analyses of cosmological data suggest the presence of an extra relativistic component beyond the Standard Model content. The Higgs–Dilaton cosmological model predicts the existence of a massless particle – the dilaton – associated with the spontaneous symmetry breaking of scale invariance and undetectable by any accelerator experiment. Its ultrarelativistic character makes it a suitable candidate for contributing to the effective number of light degrees of freedom in the Universe. In this Letter we analyze the dilaton production at the (p)reheating stage right after inflation and conclude that no extra relativistic degrees of freedom beyond those already present in the Standard Model are expected within the simplest Higgs–Dilaton scenario. The elusive dilaton remains thus essentially undetectable by any particle physics experiment or cosmological observation. 相似文献
125.
Andrew J. Thompson Dr. Jerome Dabin Javier Iglesias‐Fernández Dr. Albert Ardèvol Dr. Zoran Dinev Assoc. Prof. Spencer J. Williams Dr. Omprakash Bande Dr. Aloysius Siriwardena Carl Moreland Dr. Ting‐Chou Hu David K. Smith Prof. Harry J. Gilbert Prof. Carme Rovira Prof. Gideon J. Davies 《Angewandte Chemie (International ed. in English)》2012,51(44):11171-11171
126.
Dr. Noemi Linares Dr. Erika De Oliveira Jardim Dr. Geetu Sharma Dr. Elena Serrano Prof. Alexandra Navrotsky Prof. Dr. Javier García-Martínez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(43):10045-10048
With the aim of understanding the thermochemistry of the introduction of mesoporosity in zeolites by using surfactants, high temperature oxide melt solution calorimetry was used to determine the change in the enthalpy of formation of USY zeolite before and after the introduction of mesoporosity. Our results confirm that this process only slightly destabilizes the zeolite by the additional surface area. However, this can be overcome by the stabilizing effect of the interactions between the surfactant and the zeolite framework. 相似文献
127.
128.
Inaki Merideno Javier Nieto Nere Gil-Negrete José Germán Giménez Ortiz Aitor Landaberea Jon Iartza 《Journal of sound and vibration》2014
This paper presents a procedure for predicting the damping added to a railway wheel when sandwich-type dampers are installed. Although there are different ways to reduce the noise generated by a railway wheel, most devices are based on the mechanism of increasing wheel damping. This is why modal damping ratios are a clear indicator of the efficiency of the damping device and essential when a vibro-acoustic study of a railway wheel is carried out. Based on a number of output variables extracted from the wheel and damper models, the strategy explained herein provides the final damping ratios of the damped wheel. Several different configurations are designed and experimentally tested. Theoretical and experimental results agree adequately, and it is demonstrated that this procedure is a good tool for qualitative comparison between different solutions in the design stages. 相似文献
129.
130.
Javier Alcaraz Nuria RamónJosé L. Ruiz Inmaculada Sirvent 《European Journal of Operational Research》2013
The existence of alternate optima for the DEA weights may reduce the usefulness of the cross-efficiency evaluation, since the ranking provided depends on the choice of weights that the different DMUs make. In this paper, we develop a procedure to carry out the cross-efficiency evaluation without the need to make any specific choice of DEA weights. The proposed procedure takes into consideration all the possible choices of weights that all the DMUs can make, and yields for each unit a range for its possible rankings instead of a single ranking. This range is determined by the best and the worst rankings that would result in the best and the worst scenarios of each unit across all the DEA weights of all the DMUs. This approach might identify good/bad performers, as those that rank at the top/bottom irrespective of the weights that are chosen, or units that outperform others in all the scenarios. In addition, it may be used to analyze the stability of the ranking provided by the standard cross-efficiency evaluation. 相似文献