全文获取类型
收费全文 | 695篇 |
免费 | 36篇 |
国内免费 | 3篇 |
专业分类
化学 | 468篇 |
晶体学 | 3篇 |
力学 | 31篇 |
数学 | 88篇 |
物理学 | 144篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 17篇 |
2020年 | 17篇 |
2019年 | 19篇 |
2018年 | 12篇 |
2017年 | 20篇 |
2016年 | 27篇 |
2015年 | 18篇 |
2014年 | 29篇 |
2013年 | 60篇 |
2012年 | 42篇 |
2011年 | 50篇 |
2010年 | 28篇 |
2009年 | 18篇 |
2008年 | 31篇 |
2007年 | 34篇 |
2006年 | 29篇 |
2005年 | 28篇 |
2004年 | 31篇 |
2003年 | 26篇 |
2002年 | 18篇 |
2001年 | 9篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1974年 | 5篇 |
1971年 | 3篇 |
1966年 | 4篇 |
1954年 | 3篇 |
排序方式: 共有734条查询结果,搜索用时 0 毫秒
731.
Prakash KshirsagarShiv Shankar Sangaru Maria Ada MalvindiLuigi Martiradonna Roberto Cingolani Pier Paolo Pompa 《Colloids and surfaces. A, Physicochemical and engineering aspects》2011,392(1):264-270
In this report we demonstrate a green chemical approach for the synthesis of stable silver nanoparticles in aqueous medium using tyrosine as an efficient photoreducing agent. A narrow size distribution of silver nanoparticles can be achieved by this simple photoirradiation method without using any additional stabilizing agents or surfactants. Two different irradiation sources have been explored resulting in a different particle size distribution pattern in each case. Further, we show that starting from a polydisperse tyrosine synthesized silver nanoparticles sample, it is also possible to fractionate them into different size ranges. The size fractionation was achieved by a 2 stage phase transfer method employing different organic solvents. The nanoparticles synthesized were characterized using UV-vis spectroscopy, Transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. 相似文献
732.
Dash J Waller ZA Pantoş GD Balasubramanian S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(16):4571-4581
Herein, we report the design, synthesis and biophysical evaluation of novel 1,2,3-triazole-linked diethynyl-pyridine amides and trisubstituted diethynyl-pyridine amides as promising G-quadruplex binding ligands. We have used a Cu(I)-catalysed azide-alkyne cycloaddition click reaction to prepare the 1,2,3-triazole-linked diethynyl-pyridine amides. The G-quadruplex DNA binding properties of the ligands have been examined by using a F?rster resonance energy transfer (FRET) melting assay and surface plasmon resonance (SPR) experiments. The investigated compounds are conformationally flexible, having free rotation around the triple bond, and exhibit enhanced G-quadruplex binding stabilisation and specificity between intramolecular promoter G-quadruplex DNA motifs compared to the first generation of diaryl-ethynyl amides (J. Am. Chem. Soc. 2008, 130, 15950-15956). The ligands show versatility in molecular recognition and promising G-quadruplex discrimination with 2-50-fold selectivity exhibited between different intramolecular promoter G-quadruplexes. Circular dichroism (CD) spectroscopic analysis suggested that at higher concentration these ligands disrupt the c-kit2 G-quadruplex structure. The studies validate the design concept of the 1,3-diethynyl-pyridine-based scaffold and demonstrate that these ligands exhibit not only significant selectivity over duplex DNA but also variation in G-quadruplex interaction properties based on small chemical changes in the scaffold, leading to unprecedented differential recognition of different DNA G-quadruplex sequences. 相似文献
733.
The effects of discontinuously time-varying perturbations on the dynamics of a particle moving in harmonic, symmetric double well and symmetric triple well potentials, are investigated both classically and quantum mechanically. The quantum dynamics is followed using the time-dependent Fourier grid Hamiltonian (TDFGH) method while the classical dynamics is analyzed within the framework of classical Hamiltonian mechanics. Depending on the spatial symmetry of the perturbation and the characteristic features of the reversal time , different types of ‘phase space’ structures are observed in each of the potentials. For symmetric double and triple well potentials, quantum dynamics reveals that complete destruction of tunnelling (CDT) can be achieved in the presence of a time-dependent spatially asymmetric perturbing field that is continuous in time. Any discontinuity in time-variation of the perturbation may induce over the barrier transition. The relevance of these results in the context of (i) tunnelling control and (ii) quantum computing with 3-state or 2-state quantum registers is briefly discussed. 相似文献
734.
We establish interior regularity for convex viscosity solutions of the special Lagrangian equation. Our result states that all such solutions are real analytic in the interior of the domain. 相似文献