全文获取类型
收费全文 | 2307篇 |
免费 | 83篇 |
国内免费 | 8篇 |
专业分类
化学 | 1481篇 |
晶体学 | 17篇 |
力学 | 39篇 |
数学 | 441篇 |
物理学 | 420篇 |
出版年
2023年 | 12篇 |
2022年 | 26篇 |
2021年 | 46篇 |
2020年 | 60篇 |
2019年 | 52篇 |
2018年 | 25篇 |
2017年 | 33篇 |
2016年 | 76篇 |
2015年 | 62篇 |
2014年 | 69篇 |
2013年 | 123篇 |
2012年 | 156篇 |
2011年 | 144篇 |
2010年 | 81篇 |
2009年 | 82篇 |
2008年 | 130篇 |
2007年 | 149篇 |
2006年 | 128篇 |
2005年 | 111篇 |
2004年 | 100篇 |
2003年 | 91篇 |
2002年 | 87篇 |
2001年 | 44篇 |
2000年 | 32篇 |
1999年 | 30篇 |
1998年 | 27篇 |
1997年 | 30篇 |
1996年 | 20篇 |
1995年 | 20篇 |
1994年 | 27篇 |
1993年 | 25篇 |
1992年 | 27篇 |
1991年 | 18篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 16篇 |
1982年 | 15篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1979年 | 8篇 |
1978年 | 15篇 |
1977年 | 16篇 |
1976年 | 13篇 |
1975年 | 15篇 |
1974年 | 15篇 |
1972年 | 6篇 |
排序方式: 共有2398条查询结果,搜索用时 15 毫秒
91.
Chemical Bonding and Pressure‐Induced Change of the Electron Configuration of Ytterbium in β‐YbAgGa2
Ulrich Schwarz Marcus Schmidt Roman Gumeniuk Walter Schnelle Michael Hanfland Konstantin Klementiev Yuri Grin 《无机化学与普通化学杂志》2004,630(1):122-126
Single‐phase polycrystalline samples of the intermetallic compound β‐YbAgGa2 were synthesized by inductive heating and subsequent annealing for eight weeks at 670 K. Magnetic properties were characterized by susceptibility measurements and indicated intermediate valence of ytterbium at ambient pressure. Angle‐dispersive X‐ray powder diffraction data of orthorhombic β‐YbAgGa2 indicate stability of the phase in the investigated pressure range from 0.1 MPa (ambient pressure) to 19 GPa. The pressure‐induced volume decrease is accompanied by an increase of the effective valence from 2.17 at ambient conditions to 2.71 at 16 GPa as evaluated by X‐ray absorption spectroscopy at the Yb LIII threshold. Analysis of the chemical bonding in β‐YbAgGa2 by integrating the electron density of the polyanion in basins as defined by the electron localization function results in an electron count Yb2.7+[(Ag0.2—)(Ga1(3b)1.0—)(Ga2(4b)1.5—)]. This finding is close to the expected values calculated by means of the Zintl rules and fits well the results of magnetic susceptibility measurements and XAS investigations. 相似文献
92.
Brian Marcus 《Israel Journal of Mathematics》1975,21(2-3):111-132
93.
Summary Let A be a symmetric N × N real-matrix-valued function on a connected region in Rn, with A positive definite a.e. and A, A−1 locally integrable. Let b and c be locally integrable, non-negative, real-valued functions on Ω, with c positive a.e. Put
a(u, v) = =
((A∇u, ∇v) + buv) dx. We consider in X the weak boundary value problem a(u, v) = =
fvcdx, all v ε X; where X is a suitable Hilbert space contained in H
loc
1,1
(Ω). Criteria are given in order that the Green's operator for this problem have an integral representation and bounded eigenfunctions;
in addition, criteria for compactness are given.
Entrata in Redazione il 21 giugno 1975.
Research was partially supported by the National Science Foundation under Grant GP-28377A2. 相似文献
94.
95.
96.
Michael S. Gruhne Dr. Maximilian H. H. Wurzenberger Marcus Lommel Dr. Jörg Stierstorfer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(35):9112-9123
Dinitraminic acid (HN(NO2)2, HDN) was prepared by ion exchange chromatography and acid-base reaction with basic copper(II) carbonate allowed the in situ preparation of copper(II) dinitramide, which was reacted with twelve nitrogen-rich ligands, for example, 4-amino-1,2,4-triazole, 1-methyl-5H-tetrazole, di(5H-tetrazolyl)-methane/-ethane/-propane/-butane. Nine of the complexes were investigated by low-temperature X-ray diffraction. In addition, all compounds were investigated by infrared spectroscopy (IR), differential thermal analysis (DTA), elemental analysis (EA) and thermogravimetric analysis (TGA) for selected compounds. Furthermore, investigations of the materials were carried out regarding their sensitivity toward impact (IS), friction (FS), ball drop impact (BDIS) and electrostatic discharge (ESD). In addition, hot plate and hot needle tests were performed. Complex [Cu(AMT)4(H2O)](DN)2, based on 1-amino-5-methyltetrazole (AMT), is most outstanding for its detonative behavior and thus also capable of initiating PETN in classical initiation experiments. Laser ignition experiments at a wavelength of 915 nm were performed for all substances and solid-state UV-Vis spectra were recorded to apprehend the ignition mechanism. 相似文献
97.
Falko Böttger‐Hiller Patrick Kempe Dr. Gerhard Cox Dr. Alexander Panchenko Dr. Nicole Janssen Dr. Albrecht Petzold Prof. Dr. Thomas Thurn‐Albrecht Lars Borchardt Dr. Marcus Rose Prof. Dr. Stefan Kaskel Colin Georgi Prof. Dr. Heinrich Lang Prof. Dr. Stefan Spange 《Angewandte Chemie (International ed. in English)》2013,52(23):6088-6091
98.
99.
100.