全文获取类型
收费全文 | 5180篇 |
免费 | 632篇 |
国内免费 | 513篇 |
专业分类
化学 | 3350篇 |
晶体学 | 48篇 |
力学 | 358篇 |
综合类 | 37篇 |
数学 | 42篇 |
物理学 | 2490篇 |
出版年
2024年 | 9篇 |
2023年 | 38篇 |
2022年 | 89篇 |
2021年 | 114篇 |
2020年 | 118篇 |
2019年 | 116篇 |
2018年 | 120篇 |
2017年 | 153篇 |
2016年 | 165篇 |
2015年 | 180篇 |
2014年 | 195篇 |
2013年 | 445篇 |
2012年 | 267篇 |
2011年 | 323篇 |
2010年 | 249篇 |
2009年 | 317篇 |
2008年 | 312篇 |
2007年 | 392篇 |
2006年 | 365篇 |
2005年 | 314篇 |
2004年 | 251篇 |
2003年 | 240篇 |
2002年 | 243篇 |
2001年 | 181篇 |
2000年 | 189篇 |
1999年 | 153篇 |
1998年 | 128篇 |
1997年 | 97篇 |
1996年 | 77篇 |
1995年 | 84篇 |
1994年 | 66篇 |
1993年 | 64篇 |
1992年 | 55篇 |
1991年 | 32篇 |
1990年 | 29篇 |
1989年 | 18篇 |
1988年 | 23篇 |
1987年 | 13篇 |
1986年 | 14篇 |
1985年 | 8篇 |
1984年 | 20篇 |
1983年 | 3篇 |
1982年 | 11篇 |
1981年 | 13篇 |
1980年 | 9篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
排序方式: 共有6325条查询结果,搜索用时 187 毫秒
21.
22.
23.
M. U. Belyi N. E. Bartnitskaya I. F. Mel'nik B. A. Okhrimenko S. M. Yablochkov 《Journal of Applied Spectroscopy》1995,62(3):564-567
T. Shevchenko Kiev University, 252022 Kiev, Pr. Akad. Glushakova, 6, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 62, No. 3, pp. 192–196, May–June, 1995. 相似文献
24.
The phase behavior of binary blends of poly(ether ether ketone) (PEEK), sulfonated PEEK, and sulfamidated PEEK with aromatic polyimides is reported. PEEK was determined to be immiscible with a poly(amide imide) (TORLON 4000T). Blends of sulfonated and sulfamidated PEEK with this poly(amide imide), however, are reported here to be miscible in all proportions. Blends of sulfonated PEEK and a poly(ether imide) (ULTEM 1000) are also reported to be miscible. Spectroscopic investigations of the intermolecular interactions suggest that formation of electron donoracceptor complexes between the sulfonated/sulfamidated phenylene rings of the PEEKs and the n-phenylene units of the polyimides are responsible for this miscibility. © 1993 John Wiley & Sons, Inc. 相似文献
25.
Marco Sangermano Mehmet Atilla Tasdelen Yusuf Yagci 《Journal of polymer science. Part A, Polymer chemistry》2007,45(21):4914-4920
Photoinitiated cationic polymerization of mono‐ and bifunctional epoxy monomers, namely cyclohexeneoxide (CHO), 4‐epoxycyclohexylmethyl‐3′,4′‐epoxycyclohexanecarboxylate (EEC), respectively by using sulphonium salts in the presence of hydroxylbutyl vinyl ether (HBVE) was studied. The real‐time FTIR spectroscopic, gel content determination, and thermal characterization studies revealed that both hydroxyl and vinyl ether functionalities of HBVE take part in the polymerization. During the polymerization, HBVE has the ability to react via both active chain end (ACE) and activated monomer mechanisms through its hydroxyl and vinyl ether functionalities, respectively. Thus, more efficient curing was observed with the addition of HBVE into EEC‐containing formulations. It was also demonstrated that HBVE is effective in facilitating the photoinduced crosslinking of monofunctional epoxy monomer, CHO in the absence of a conventional crosslinker. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4914–4920, 2007 相似文献
26.
Bart M. J. M. Suijkerbuijk Duncan M. Tooke Anthony L. Spek Gerard van Koten Robertus J. M. Klein Gebbink Prof. Dr. 《无机化学与普通化学杂志》2007,633(15):2649-2653
A tin(IV) porphyrin was combined with two axial NCN‐pincer platinum(II) fragments by utilizing the oxophilicity of the apical positions on the tin atom and the acidic nature of the NCN‐pincer platinum derived benzoic acid. The solid‐state structure determined by X‐ray crystallography revealed some close contacts between the pincer complexes and the meso‐p‐tolyl subsitutents of the porphyrin. It was shown by 1H NMR spectroscopy that these close contacts were not present in solution and that this compound can potentially act as a novel building block for supramolecular architectures. 相似文献
27.
Morphological and chemical properties of both the surface and interface of poly(vinylidene fluoride)/poly(methyl methacrylate)-co-poly(ethyl acrylate) (PVDF/PMMA-co-PEA) blend films have been investigated before and after the samples were exposed to ultraviolet (UV) irradiation using a xenon arc lamp at 50 °C and 9% relative humidity (RH) for 7 months. Surface and interfacial morphologies were studied by atomic force microscopy (AFM). Chemical composition information was obtained by confocal Raman microscopy, attenuated total reflection-FTIR spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. Results show an enrichment of the PVDF material at the air surface, while the acrylic copolymer enriches the interface. Blends having greater than 50% mass fraction of PVDF show little change in the surface morphology after UV exposure for 7 months. However, for a lower PVDF content, blends exhibit significant degradation of PMMA-co-PEA copolymer and a much rougher surface after UV exposure. Microstructural changes in the PVDF spherulites are also observed after UV degradation. It is found that the surface and interfacial morphologies are correlated with the chemical properties. 相似文献
28.
对Sn-C60薄膜进行紫外可见光吸收,X-射线衍射和扫描电镜的测定结果显示,薄膜样品紫外可见光吸收的两个短波段吸收峰比纯C60薄膜的吸收峰显著下降,说明Sn-C60薄膜的电子光吸收跃迁为间接跃迁,能带中有杂质能级的存在;样品的X射线衍射峰则对应于面心立方结构;扫描电镜结果显示薄膜为纳米级颗粒组成。 相似文献
29.
30.