全文获取类型
收费全文 | 88970篇 |
免费 | 1295篇 |
国内免费 | 1218篇 |
专业分类
化学 | 32633篇 |
晶体学 | 895篇 |
力学 | 7003篇 |
综合类 | 66篇 |
数学 | 33758篇 |
物理学 | 17128篇 |
出版年
2023年 | 124篇 |
2022年 | 153篇 |
2021年 | 367篇 |
2020年 | 383篇 |
2019年 | 350篇 |
2018年 | 10634篇 |
2017年 | 10455篇 |
2016年 | 6560篇 |
2015年 | 1333篇 |
2014年 | 859篇 |
2013年 | 1126篇 |
2012年 | 4786篇 |
2011年 | 11554篇 |
2010年 | 6338篇 |
2009年 | 6658篇 |
2008年 | 7411篇 |
2007年 | 9524篇 |
2006年 | 977篇 |
2005年 | 1928篇 |
2004年 | 2060篇 |
2003年 | 2310篇 |
2002年 | 1304篇 |
2001年 | 391篇 |
2000年 | 408篇 |
1999年 | 280篇 |
1998年 | 266篇 |
1997年 | 216篇 |
1996年 | 273篇 |
1995年 | 165篇 |
1994年 | 125篇 |
1993年 | 147篇 |
1992年 | 101篇 |
1991年 | 97篇 |
1990年 | 89篇 |
1989年 | 89篇 |
1988年 | 82篇 |
1987年 | 83篇 |
1986年 | 73篇 |
1985年 | 73篇 |
1984年 | 64篇 |
1983年 | 50篇 |
1982年 | 51篇 |
1981年 | 48篇 |
1980年 | 60篇 |
1979年 | 55篇 |
1978年 | 42篇 |
1914年 | 45篇 |
1912年 | 41篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Dr. Yolimar Gil Dr. Alejandro Castro-Alvarez Dr. Pablo Fuentealba Prof. Evgenia Spodine Dr. Daniel Aravena 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(48):e202200336
Enhancement of axial magnetic anisotropy is the central objective to push forward the performance of Single-Molecule Magnet (SMM) complexes. In the case of mononuclear lanthanide complexes, the chemical environment around the paramagnetic ion must be tuned to place strongly interacting ligands along either the axial positions or the equatorial plane, depending on the oblate or prolate preference of the selected lanthanide. One classical strategy to achieve a precise chemical environment for a metal centre is using highly structured, chelating ligands. A natural approach for axial-equatorial control is the employment of macrocycles acting in a belt conformation, providing the equatorial coordination environment, and leaving room for axial ligands. In this review, we present a survey of SMMs based on the macrocycle belt motif. Literature systems are divided in three families (crown ether, Schiff-base and metallacrown) and their general properties in terms of structural stability and SMM performance are briefly discussed. 相似文献
3.
氧化铝晶体是一种优良的光学透明窗口材料,更是地球内部的重要组成物质.利用气炮加载结合冲击光谱测量,不仅能够获得其发光特征,并且根据光谱分布特征得到高压结构相变信息.在自主搭建的冲击光谱动态测试平台上,结合多通道辐射高温计以及ICCD瞬态光谱测试技术在40~120 GPa的压力区间,研究了c切向氧化铝晶体的辐射发光效应.在可见光波段400~700 nm区间获得了氧化铝晶体的发光光谱和辐射温度结果,证实了光谱的结构特征和表观温度值与该压力下氧化铝的结构相变存在明显的关联性. 相似文献
4.
In the paper, the authors establish several integral representations for the generating functions of the large and little Schröder numbers and for the large and little Schröder numbers. 相似文献
5.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant. 相似文献
6.
7.
Sarah Peluse 《Israel Journal of Mathematics》2018,227(1):379-396
We prove that the group of diffeomorphisms of the interval [0, 1] contains surface groups whose action on (0, 1) has no global fix point and such that only countably many points of the interval (0, 1) have non-trivial stabiliser. 相似文献
8.
9.
10.
Mathieu Boiret Anna de Juan Nathalie Gorretta Yves-Michel Ginot Jean-Michel Roger 《Analytica chimica acta》2015
Raman chemical imaging provides chemical and spatial information about pharmaceutical drug product. By using resolution methods on acquired spectra, the objective is to calculate pure spectra and distribution maps of image compounds. With multivariate curve resolution-alternating least squares, constraints are used to improve the performance of the resolution and to decrease the ambiguity linked to the final solution. Non negativity and spatial local rank constraints have been identified as the most powerful constraints to be used. 相似文献