全文获取类型
收费全文 | 2329篇 |
免费 | 51篇 |
国内免费 | 7篇 |
专业分类
化学 | 1537篇 |
晶体学 | 14篇 |
力学 | 45篇 |
数学 | 235篇 |
物理学 | 556篇 |
出版年
2022年 | 53篇 |
2021年 | 56篇 |
2020年 | 40篇 |
2019年 | 46篇 |
2018年 | 26篇 |
2017年 | 30篇 |
2016年 | 48篇 |
2015年 | 47篇 |
2014年 | 68篇 |
2013年 | 110篇 |
2012年 | 119篇 |
2011年 | 146篇 |
2010年 | 83篇 |
2009年 | 63篇 |
2008年 | 114篇 |
2007年 | 108篇 |
2006年 | 99篇 |
2005年 | 81篇 |
2004年 | 62篇 |
2003年 | 65篇 |
2002年 | 68篇 |
2001年 | 50篇 |
2000年 | 41篇 |
1999年 | 39篇 |
1998年 | 26篇 |
1997年 | 33篇 |
1996年 | 27篇 |
1995年 | 31篇 |
1994年 | 30篇 |
1993年 | 28篇 |
1992年 | 28篇 |
1991年 | 17篇 |
1990年 | 23篇 |
1989年 | 18篇 |
1988年 | 23篇 |
1987年 | 18篇 |
1986年 | 25篇 |
1985年 | 28篇 |
1984年 | 17篇 |
1983年 | 22篇 |
1982年 | 29篇 |
1981年 | 20篇 |
1980年 | 31篇 |
1979年 | 16篇 |
1978年 | 19篇 |
1977年 | 17篇 |
1976年 | 16篇 |
1975年 | 17篇 |
1974年 | 21篇 |
1973年 | 15篇 |
排序方式: 共有2387条查询结果,搜索用时 14 毫秒
101.
102.
Mariana Graña 《Letters in Mathematical Physics》2006,78(3):279-305
String theory is consistently defined in ten dimensions. In order to extract any information about four-dimensional physics, we need to understand the properties of the six-dimensional compact manifold orthogonal to our four-dimensional universe. A possibility that is being very much explored lately is to look at manifolds on which background fluxes are turned on. In this article, we present an introduction to string theory, focusing on its massless sector. We then review traditional compactifications to four–dimensions, and finally motivate and describe the so-called flux compactifications. We interpret the allowed six-dimensional manifolds from the point of view of generalized complex geometry. 相似文献
103.
Mariana Köber Enrique Sahagún Martina Fuss Fernando Briones Mónica Luna Juan José Sáenz 《固体物理学:研究快报》2008,2(3):138-140
The effects of adhesion hysteresis in the dynamic‐dissipation curves measured in amplitude‐modulation atomic force microscopy are discussed. Hysteresis in the interaction forces is shown to modify the dynamics of the cantilever leading to different power dissipation curves in the repulsive and attractive regimes. Experimental results together with numerical simulations show that power dissipation, as measured in force microscopy, is not always proportional to the energy dissipated in the tip–sample interaction process. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
104.
The relativistic mean-field models tested in previous works against nuclear matter experimental values,critical parameters and macroscopic stellar properties are revisited and used in the evaluation of the symmetry energyγ parameter obtained in three different ways. We have checked that, independent of the choice made to calculate theγ values, a trend of linear correlation is observed between γ and the symmetry energy(S_0) and a more clear linear relationship is established between γ and the slope of the symmetry energy(L_0). These results directly contribute to the arising of other linear correlations between γ and the neutron star radii of R_(1.0) and R_(1.4), in agreement with recent findings. Finally, we have found that short-range correlations induce two specific parametrizations, namely,IU-FSU and DD-MEδ, simultaneously compatible with the neutron star mass constraint of 1.93≤M_(max)/M_☉≤2.05 and with the overlap band for the L_0 ×S_0 region, to present γ in the range of γ=0.25±0.05. 相似文献
105.
106.
Qiu-Cheng Chen Zi-Ye Xiao Shachar Fite Dr. Amir Mizrahi Dr. Natalia Fridman Xuan Zhan Or Keisar Dr. Yair Cohen Prof. Dr. Zeev Gross 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(48):11383-11388
Although the affinity of metallocorroles to axial ligands is quite low, this is not the case when the chelated element is phosphorus. This work is hence focused on the mechanism of ligand exchange of six-coordinate phosphorus corroles as a tool for affecting their chemical and physical properties. These fundamental investigations allowed for the development of facile methodologies for the synthesis of a large series of complexes and the establishment of several new structure/activity profiles that may be used to understand and predict spectroscopic features and for tailor-made modification of photophysical and electrochemical properties. This is exemplified by the facile access to complexes with terminal groups that are of large potential for practical applications based on click chemistry, optical imaging, and surface science. 相似文献
107.
Nora Jannsen Dr. Stefano Diodati Nicola Dengo Francesca Tajoli Dr. Nicola Vicentini Dr. Giacomo Lucchini Prof. Adolfo Speghini Prof. Denis Badocco Prof. Paolo Pastore Prof. Silvia Gross 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(59):13624-13634
The aim of this work was i) to develop a hydrothermal, low-temperature synthesis protocol affording the upconverting hexagonal phase NaYF4 with suitable dopants while adhering to the “green chemistry” standards and ii) to explore the effect that different parameters have on the products. In optimizing the synthesis protocol, short reaction times and low temperatures (below 150 °C) were considered. Yb3+ and Er3+ ions were chosen as dopants for the NaYF4 material. Within the context of the second goal, parameters including nature of the precursors, treatment temperature, and treatment time were investigated to afford a pure hexagonal crystalline phase, both in the doped and undoped materials. To fully explore the synthesis results, the prepared materials were characterized from a structural (XRD), compositional (XPS, ICP-MS), and morphological (SEM) point of view. The upconverting properties of the compounds were confirmed by photoluminescence measurements. 相似文献
108.
Aysun apc Mlanie M. Lorion Hui Wang Nina Simon Maria Leidenberger Mariana C. BorgesSilva Diogo R. M. Moreira Yongping Zhu Yuqing Meng Jia Yun Chen Yew Mun Lee Oliver Friedrich Barbara Kappes Jigang Wang Lutz Ackermann Svetlana B. Tsogoeva 《Angewandte Chemie (International ed. in English)》2019,58(37):13161-13161
109.
While single compound semiconductors were initially used for photocatalysis, combining two compounds to form a heterojunction significantly increases the photocatalysis performance. This review will outline how heterojunctions are superior, explain the different heterostructure architectures assembled from nanoparticles, and discuss the importance of achieving a large and quality contact in the junction, the heterojunction. Reference is made to methods for increasing the charge carrier performance and reducing recombination. Solution-based synthesis approaches, have been selected as the preferred route of manufacture, for the low cost scalability, and ability to combine a larger number of compounds. The main objective of this review article is to provide insight to the range of chemical solution-based methods for forming chemically bonded junction in nanoheterostructures for photocatalysis. Methods include chemical precipitation, impregnation, chemical bath deposition, hot injection, solvothermal, photo-deposition, electrochemical deposition, cation exchange and linker assisted assembly. The synthesis of different photocatalysts is addressed for each synthesis method. Solution synthesis is offered for coupling oxide semiconductors (i.e. TiO2, ZnO, WO3, Fe2O3, BiVO4) with other oxides or metal chalcogenide quantum dots or metallic plasmonic nanoparticles. 相似文献
110.
Haifeng Xu Mariana Medina-Sánchez Oliver G. Schmidt 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(35):15139-15147
An integrated system combining a magnetically-driven micromotor and a synthetized protein-based hyaluronic acid (HA) microflake is presented for the in situ selection and transport of multiple motile sperm cells (ca. 50). The system appeals for targeted sperm delivery in the reproductive system to assist fertilization or to deliver drugs. The binding mechanism between the HA microflake and sperm relies on the interactions between HA and the corresponding sperm HA receptors. Once sperm are captured within the HA microflake, the assembly is trapped and transported by a magnetically-driven helical microcarrier. The trapping of the sperm-microflake occurs by a local vortex induced by the microcarrier during rotation-translation under a rotating magnetic field. After transport, the microflake is enzymatically hydrolyzed by local proteases, allowing sperm to escape and finally reach the target location. This cargo-delivery system represents a new concept to transport not only multiple motile sperm but also other actively moving biological cargoes. 相似文献