全文获取类型
收费全文 | 15459篇 |
免费 | 747篇 |
国内免费 | 145篇 |
专业分类
化学 | 10390篇 |
晶体学 | 102篇 |
力学 | 431篇 |
数学 | 2761篇 |
物理学 | 2667篇 |
出版年
2023年 | 140篇 |
2022年 | 104篇 |
2021年 | 299篇 |
2020年 | 403篇 |
2019年 | 386篇 |
2018年 | 256篇 |
2017年 | 223篇 |
2016年 | 607篇 |
2015年 | 480篇 |
2014年 | 567篇 |
2013年 | 873篇 |
2012年 | 1125篇 |
2011年 | 1315篇 |
2010年 | 678篇 |
2009年 | 585篇 |
2008年 | 989篇 |
2007年 | 948篇 |
2006年 | 940篇 |
2005年 | 840篇 |
2004年 | 722篇 |
2003年 | 498篇 |
2002年 | 463篇 |
2001年 | 129篇 |
2000年 | 113篇 |
1999年 | 110篇 |
1998年 | 84篇 |
1997年 | 105篇 |
1996年 | 147篇 |
1995年 | 105篇 |
1994年 | 109篇 |
1993年 | 118篇 |
1992年 | 82篇 |
1991年 | 92篇 |
1990年 | 69篇 |
1989年 | 68篇 |
1988年 | 83篇 |
1987年 | 68篇 |
1986年 | 63篇 |
1985年 | 98篇 |
1984年 | 104篇 |
1982年 | 114篇 |
1981年 | 122篇 |
1980年 | 96篇 |
1979年 | 84篇 |
1978年 | 113篇 |
1977年 | 92篇 |
1976年 | 73篇 |
1975年 | 71篇 |
1974年 | 64篇 |
1973年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Daniel R. Phillips 《Few-Body Systems》2014,55(8-10):931-934
I discuss recent work our group has undertaken on effective-field-theory analyses of experimental data pertaining to one- and two-neutron halo nuclei. 相似文献
83.
Roy Rotstein Samir Mitragotri Martin Moskovits Daniel E. Morse 《Journal of Polymer Science.Polymer Physics》2014,52(9):611-617
The synthesis and characterization of highly ordered three‐dimensional photonic crystals have been the subjects of intense study over the past two decades due to the unique ability of these structures to control light at the nanoscale. Building on that work in recent years, increasing interest is now focused on the unique optical properties of disordered and quasi‐ordered photonic structures. We present a study of the effects of shape anisotropy and disorder on the specular reflection properties of polymer‐based colloidal films comprised of rod‐shaped subunits of varying aspect ratio. We characterize the specular reflectance properties of these films as a function of their increasing levels of disorder, demonstrating progressive transition from resonant reflection to diffuse reflection. The onset of the diffuse reflection is governed by particle size. © 2014 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys. 2014 , 52, 611–617 相似文献
84.
A Series of Diamagnetic Pyridine Monoimine Rhenium Complexes with Different Degrees of Metal‐to‐Ligand Charge Transfer: Correlating 13C NMR Chemical Shifts with Bond Lengths in Redox‐Active Ligands 下载免费PDF全文
Dr. Daniel Sieh Prof. Dr. Clifford P. Kubiak 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10638-10650
A set of pyridine monoimine (PMI) rhenium(I) tricarbonyl chlorido complexes with substituents of different steric and electronic properties was synthesized and fully characterized. Spectroscopic (NMR and IR) and single‐crystal X‐ray diffraction analyses of these complexes showed that the redox‐active PMI ligands are neutral and that the overall electronic structure is little affected by the choices of the substituent at the ligand backbone. One‐ and two‐electron reduction products were prepared from selected starting compounds and could also be characterized by multiple spectroscopic methods and X‐ray diffraction. The final product of a one‐electron reduction in THF is a diamagnetic metal–metal‐bonded dimer after loss of the chlorido ligand. Bond lengths in and NMR chemical shifts of the PMI ligand backbone indicate partial electron transfer to the ligand. Two‐electron reduction in THF also leads to the loss of the chlorido ligand and a pentacoordinate complex is obtained. The comparison with reported bond lengths and 13C NMR chemical shifts of doubly reduced free pyridine monoaldimine ligands indicates that both redox equivalents in the doubly reduced rhenium complex investigated here are located in the PMI ligand. With diamagnetic complexes varying over three formal reduction stages at the PMI ligand we were, for the first time, able to establish correlations of the 13C NMR chemical shifts with the relevant bond lengths in redox‐active ligands over a full redox series. 相似文献
85.
86.
Continuous‐Flow Microwave Synthesis of Metal–Organic Frameworks: A Highly Efficient Method for Large‐Scale Production 下载免费PDF全文
Dr. Marco Taddei Daniel Antti Steitz Prof. Dr. Jeroen Anton van Bokhoven Dr. Marco Ranocchiari 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3245-3249
Metal–organic frameworks are having a tremendous impact on novel strategic applications, with prospective employment in industrially relevant processes. The development of such processes is strictly dependent on the ability to generate materials with high yield efficiency and production rate. We report a versatile and highly efficient method for synthesis of metal–organic frameworks in large quantities using continuous flow processing under microwave irradiation. Benchmark materials such as UiO‐66, MIL‐53(Al), and HKUST‐1 were obtained with remarkable mass, space–time yields, and often using stoichiometric amounts of reactants. In the case of UiO‐66 and MIL‐53(Al), we attained unprecedented space–time yields far greater than those reported previously. All of the syntheses were successfully extended to multi‐gram high quality products in a matter of minutes, proving the effectiveness of continuous flow microwave technology for the large scale production of metal–organic frameworks. 相似文献
87.
Back Cover: Co‐existence of Two Different α‐Synuclein Oligomers with Different Core Structures Determined by Hydrogen/Deuterium Exchange Mass Spectrometry (Angew. Chem. Int. Ed. 29/2014) 下载免费PDF全文
88.
Daniel Schultz 《The Ramanujan Journal》2014,34(1):119-128
A short and simple proof of the Rogers–Selberg identities is obtained from the work of Andrew Sills on identities of the Rogers–Ramanujan type. 相似文献
89.
Amit Madhukar Daniel PerlitzMichael Grigola Donghai GaiK. Jimmy Hsia 《International Journal of Solids and Structures》2014
We apply a finite element analysis to examine the stability of spherical, thick-walled domes undergoing large deformation. We identify three energetic states, mono-stable, bi-stable, and pseudo-bi-stable that uniquely characterize the behavior of the dome during deformation. An empirical relation is developed using finite element simulations relating the stability of the dome to pertinent geometric parameters like height, length and thickness, which is verified experimentally. Using this relation, similar domes can be designed to have desired stability characteristics. 相似文献
90.