全文获取类型
收费全文 | 2378篇 |
免费 | 83篇 |
国内免费 | 30篇 |
专业分类
化学 | 1524篇 |
晶体学 | 27篇 |
力学 | 58篇 |
数学 | 450篇 |
物理学 | 432篇 |
出版年
2023年 | 16篇 |
2022年 | 13篇 |
2021年 | 83篇 |
2020年 | 50篇 |
2019年 | 55篇 |
2018年 | 45篇 |
2017年 | 43篇 |
2016年 | 92篇 |
2015年 | 75篇 |
2014年 | 99篇 |
2013年 | 147篇 |
2012年 | 138篇 |
2011年 | 147篇 |
2010年 | 101篇 |
2009年 | 105篇 |
2008年 | 137篇 |
2007年 | 147篇 |
2006年 | 122篇 |
2005年 | 111篇 |
2004年 | 102篇 |
2003年 | 83篇 |
2002年 | 60篇 |
2001年 | 38篇 |
2000年 | 41篇 |
1999年 | 33篇 |
1998年 | 40篇 |
1997年 | 25篇 |
1996年 | 24篇 |
1995年 | 26篇 |
1994年 | 25篇 |
1993年 | 21篇 |
1992年 | 28篇 |
1991年 | 21篇 |
1990年 | 17篇 |
1989年 | 19篇 |
1988年 | 16篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 26篇 |
1984年 | 18篇 |
1983年 | 9篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1974年 | 4篇 |
1937年 | 5篇 |
1936年 | 7篇 |
排序方式: 共有2491条查询结果,搜索用时 312 毫秒
81.
Jolanta Klocek Krzysztof Kolanek Dieter Schmeißer 《Journal of Physics and Chemistry of Solids》2012,73(5):699-706
Fullerene based materials may open a new horizon in many fields of science. In this study we fabricated thin films of the hybrid materials formed as a result of interactions between C60 fullerenes and 3-aminopropyltrimethoxysilane (APTMS). The deposition technique was a combination of spin-coating and evaporation methods. Interactions within the films were investigated by means of X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure spectroscopy (NEXAFS). Surface morphology was measured by atomic force microscopy (AFM). We found that there are strong chemical reactions between the nucleophilic nitrogen atoms from APTMS and electrophilic fullerene molecules. Results of NEXAFS investigations suggest that due to direct interactions between APTMS and C60 the electronic structure of the fullerene molecules changes while at the same time AFM proved that the C60 molecule diameter is not altered. 相似文献
82.
Dr. Joice Thomas Dr. Liliana Dobrzańska Prof. Luc Van Meervelt Prof. Mario Alfredo Quevedo Prof. Krzysztof Woźniak Marcin Stachowicz Prof. Mario Smet Prof. Wouter Maes Prof. Wim Dehaen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(3):979-987
A synthetic route towards homodiselenacalix[4]arene macrocycles is presented, based on the dynamic covalent chemistry of diselenides. The calixarene inner rim is decorated with either alkoxy or tert‐butyl ester groups. Single‐crystal X‐ray analysis of two THF solvates with methoxy and ethoxy substituents reveals the high similarity of their molecular structures and alterations on the supramolecular level. In both crystal structures, solvent channels are present and differ in both shape and capacity. Furthermore, the methoxy‐substituted macrocycle undergoes a single‐crystal‐to‐single‐crystal transformation during which the molecular structure changes its conformation from 1,3‐alternate (loaded with THF/water) to 1,2‐alternate (apohost form). Molecular modelling techniques were applied to explore the conformational and energetic behaviour of the macrocycles. 相似文献
83.
Krzysztof Wojciechowski 《合成通讯》2013,43(17):2415-2422
Aza-ortho-xylylenes 4 generated via thermal extrusion of SO2 from 1,3-dihydro-2,1-benzisothiazolo-3-spiro-2′-indan 2,2-dioxides 3 undergo [1,5] hydrogen shift giving 2-phenylindene derivatives 5 in good yields. 相似文献
84.
Scott Gaynor Dorota Greszta Daniela Mardare Mircea Teodorescu Krzysztof Matyjaszewski 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):1561-1578
Various methods which lead to the control of molecular weight and polydispersities, and which allow for the preparation of block copolymers by radical polymerization are discussed. Thermal polymerizationof styrenes in the presence of stable radicals, polymerization of vinyl acetate and methyl methacrylate in the presence of chromium complexed by macrocyclic ligands polymerization of vinyl acetate initiated by organoaluminum compounds complexed by dipyridyl and activated by stable radicals, as well as in the presence of phosphites, are described in detail. 相似文献
85.
Krzysztof A. Kunert 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):1469-1488
In this paper are presented the static and dynamic mechanical investigation of chemically cross-linked low density polyethylene (XLPE) prepared in our laboratory. This polymer has been tested mechanically at different frequencies, amplitudes, and temperatures as a function of cross-link density which is indicated to some extent by the amount of peroxide used in the cross-linking. The main findings can be described as follows: mechanical damping in XLPE at the α-relaxation point as a function of peroxide concentration is different for shear and compression modes of deformation. Moreover, the dynamic investigation at very small amplitudes indicated two relatively rigid structures. One structure at low concentration of peroxide is attributed to excessive crystallinity; the other one at the high peroxide concentration is probably due to the very regular and perfect polyethylene network. These two interesting structures are not detected by dynamical testing with large amplitudes. As far as Young's modulus as a function of peroxide concentration is concerned, we conclude that in this polymer this factor does not depend on the crystallinity but on changes of the so-called hard amorphous phase. These findings are consistent with our previous structural investigation. 相似文献
86.
87.
88.
Krzysztof Bolibok 《Central European Journal of Mathematics》2012,10(6):2211-2214
We give a lower bound for the minimal displacement characteristic in the space l ∞. 相似文献
89.
90.
Krzysztof Garman Ewa Olewnik Wojciech Czerwiński 《Journal of Thermal Analysis and Calorimetry》2013,111(1):799-805
This article presents the results of investigation into receiving amide modification agents of smectic clays, used as nanofillers in polymer nanocomposites. Prepared materials were obtained on the base of terephthalic and isophthalic acids and simple aliphatic amines. Such structure makes them good layered silicates modifying agents as well as makes them well affiliate to structure of polymers containing aromatic, carbonyl, amide, etc. groups. Obtained compounds were introduced into clays’ structure in protonated form, according to formulated method. Conducted research confirmed that the modification of montmorillonite clay (MMT) with received compounds had taken place. In order to establish that fact elementary analysis and X-ray diffraction (XRD) methods were used. Modificator molecules must display thermal resistance in full range of polymer processing temperatures. To investigate these properties the Thermogravimetric analysis (TG) of obtained compounds was carried out. These studies indicate that among the obtained compounds there were the ones with thermal stability over 523 K. Thermal resistance makes it possible for these substances to be used in poly(ethylene terephthalate) processing. 相似文献