全文获取类型
收费全文 | 2980篇 |
免费 | 101篇 |
国内免费 | 22篇 |
专业分类
化学 | 1918篇 |
晶体学 | 21篇 |
力学 | 59篇 |
数学 | 587篇 |
物理学 | 518篇 |
出版年
2023年 | 16篇 |
2022年 | 69篇 |
2021年 | 73篇 |
2020年 | 71篇 |
2019年 | 81篇 |
2018年 | 67篇 |
2017年 | 58篇 |
2016年 | 121篇 |
2015年 | 108篇 |
2014年 | 129篇 |
2013年 | 224篇 |
2012年 | 192篇 |
2011年 | 204篇 |
2010年 | 145篇 |
2009年 | 147篇 |
2008年 | 179篇 |
2007年 | 172篇 |
2006年 | 137篇 |
2005年 | 115篇 |
2004年 | 93篇 |
2003年 | 70篇 |
2002年 | 80篇 |
2001年 | 31篇 |
2000年 | 37篇 |
1999年 | 27篇 |
1998年 | 17篇 |
1997年 | 21篇 |
1996年 | 34篇 |
1995年 | 26篇 |
1994年 | 22篇 |
1993年 | 18篇 |
1992年 | 25篇 |
1991年 | 12篇 |
1990年 | 20篇 |
1989年 | 12篇 |
1988年 | 17篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 14篇 |
1984年 | 23篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 21篇 |
1977年 | 20篇 |
1976年 | 11篇 |
1970年 | 6篇 |
1968年 | 8篇 |
排序方式: 共有3103条查询结果,搜索用时 15 毫秒
181.
Mapping the conformational space of a polypeptide onto a network of conformational states involves a number of subjective choices, mostly in relation to the definition of conformation and its discrete nature in a network framework. Here, we evaluate the robustness of the topology of conformational‐space networks derived from Molecular Dynamics (MD) simulations with respect to the use of different discretization (clustering) methods, variation of their parameters, simulation length and analysis time‐step, and removing high‐frequency motions from the coordinate trajectories. In addition, we investigate the extent to which polypeptide dynamics can be reproduced on the resulting networks when assuming Markovian behavior. The analysis is based on eight 500 ns and eight 400 ns MD simulations in explicit water of two 10‐residue peptides. Three clustering algorithms were used, two of them based on the pair‐wise root‐mean‐square difference between structures and one on dihedral‐angle patterns. A short characteristic path length and a power‐law behavior of the probability distribution of the node degree are obtained irrespective of the clustering method or the value of any of the tested parameters. The average cliquishness is consistently one or two orders of magnitude larger than that of a random realization of a network of corresponding size and connectivity. The cliquishness as function of node degree and the kinetic properties of the networks are found to be most dependent on clustering method and/or parameters. Although Markovian simulations on the networks reproduce cluster populations accurately, their kinetic properties most often differ from those observed in the MD simulations. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
182.
Roman Staník Jan Světlík Ivan Benkovsky 《Journal of Radioanalytical and Nuclear Chemistry》2012,293(2):545-554
Meso-2,3-dimercaptosuccinic acid (DMSA) forms stable complexes with a remarkable wide range of metal ions. This relatively small molecule has attracted increasing attention in the field of radiopharmacy, treatment of heavy metal intoxications and nanoparticles preparation. In this review detailed summary of all physical, chemical and biological properties of DMSA and its complex compounds with 99mTc, 186/188Re, 166Ho, 177Lu and 90Y is provided. The clinical utilisation of DMSA complexes in the nuclear medicine and its use for treatment of heavy metal intoxication is briefly summarised. The aspects of its application in the field of nanoparticles preparation is behind the scope of this review, therefore it is only shortly described. 相似文献
183.
The indirect (through-bridge) components of chemical interactions between atomic orbitals (AO) are shown to originate from the indirect dependencies between
AO due to the orbital intermediaries in the bond system of the molecule. They are expressed in terms of the bridge-coupling
elements of the density matrix via the chain rule transformation of the implicit derivatives between the indirectly bonded AO in the molecular bond system.
The elements of the charge-and-bond-order (CBO) matrix are interpreted as the canonical derivatives between the AO-projections
onto the bond subspace combining the occupied Molecular Orbitals (MO). The chain-rule manipulations are then used to express
the scattering amplitudes via AO intermediaries in terms of the relevant elements of the CBO matrix. The squares of such amplitudes are related to the
Wiberg-type indirect bond components, which complement the familiar direct Wiberg bond-order contributions. The interference implications of the probability scatterings via the multiple cascades involving all basis functions are examined. These probability propagations are shown to preserve the
stationary conditional probabilities of the underlying molecular communication channel in AO resolution. 相似文献
184.
We consider homomorphisms from a normed space into a topological group. Assuming their boundedness in a neighbourhood (in relative topology) of an extremal point of the unit sphere, we derive their linearity (whenever it makes sense), closedness of the graph or continuity. 相似文献
185.
186.
Dr. Isaac Omari Dr. Lars P. E. Yunker Dr. Johanne Penafiel Darlene Gitaari Atzin San Roman Prof. J. Scott McIndoe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(11):3812-3816
Organotrifluoroborates serve as coupling partners during transmetalation in the Suzuki–Miyaura reaction but require hydrolysis prior to the coupling reaction. Their anionic nature allows study of their hydrolysis by electrospray ionization mass spectrometry (ESI-MS) through real-time monitoring, complemented by pH analysis. The induction period varied according to the borates employed, and a dynamic series of equilibria for numerous ions was observed during hydrolysis. We found that the induction periods and reaction rates were sensitive to the R group of the borates, the shape of the reaction vessel, and stir rate. 相似文献
187.
188.
189.
In 1960 Edward Lorenz (1917–2008) published a pioneering work on the ‘maximum simplification’ of the barotropic vorticity equation. He derived a coupled three-mode system and interpreted it as the minimum core of large-scale fluid mechanics on a ‘finite but unbounded’ domain. The model was obtained in a heuristic way, without giving a rigorous justification for the chosen selection of modes. In this paper, it is shown that one can legitimate Lorenz’ choice by using symmetry transformations of the spectral form of the vorticity equation. The Lorenz three-mode model arises as the final step in a hierarchy of models constructed via the component reduction by means of symmetries. In this sense, the Lorenz model is indeed the ‘maximum simplification’ of the vorticity equation. 相似文献
190.