全文获取类型
收费全文 | 568篇 |
免费 | 36篇 |
国内免费 | 12篇 |
专业分类
化学 | 488篇 |
晶体学 | 4篇 |
力学 | 2篇 |
数学 | 50篇 |
物理学 | 72篇 |
出版年
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 17篇 |
2020年 | 16篇 |
2019年 | 38篇 |
2018年 | 42篇 |
2017年 | 24篇 |
2016年 | 36篇 |
2015年 | 37篇 |
2014年 | 33篇 |
2013年 | 82篇 |
2012年 | 37篇 |
2011年 | 51篇 |
2010年 | 24篇 |
2009年 | 29篇 |
2008年 | 24篇 |
2007年 | 16篇 |
2006年 | 11篇 |
2005年 | 16篇 |
2004年 | 21篇 |
2003年 | 4篇 |
2002年 | 14篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1977年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有616条查询结果,搜索用时 15 毫秒
141.
142.
143.
Abdol R. Hajipour Leila Khazdooz Arnold E. Ruoho 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):705-711
A selective and efficient procedure for the oxidation of sulfides to the corresponding sulfoxides is reported using ceric ammonium nitrate in the presence of methylimidazolium hydrogensulfate as Brönsted acidic ionic liquid ([Hmim]HSO 4 ) as the solvent under mild conditions. The use of nontoxic and inexpensive materials, straightforward procedure, short reaction times, and good yields of the products are the major advantages of this method. 相似文献
144.
Leila S. Boulos Mona H. N. Arsanious Ewies F. Ewies 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):275-290
The reaction of 2-phenyl-5-(4H)-oxazolone 1 and its 4-benzylidene derivative 2 with oxovinylidenetriphenylphosphorane 3 afforded 2-phenylfuro [3,2-d] [1,3]oxazol-5-(6H)-one 6 and 2,7-diphenyl-5H-pyrano[3,2-d][1,3]oxazol-5-one 7 along with triphenylphosphine. Alternatively, when 2-phenyl-5-(4H)-oxazolone 1 reacts with phosphorus ylides 4a–f the corresponding new phosphorane, the cyclic and/or the olefinic adducts were obtained. Moreover, oxazolone reacts with N-(triphenylphosphoranylidene)aniline 5 to give the new imino product 14 together with triphenylphosphine oxide. Possible reaction mechanisms are considered and the structural assignments are based on analytical and spectroscopic results. Biological evaluations of the new products are also studied. 相似文献
145.
146.
147.
Glycodendrimers have attracted considerable interest in the field of dendrimer sciences owing to their plethora of implications in biomedical applications. This is primarily due to the fact that cell surfaces expose a wide range of highly diversified glycan architectures varying by the nature of the sugars, their number, and their natural multiantennary structures. This particular situation has led to cancer cell metastasis, pathogen recognition and adhesion, and immune cell communications that are implicated in vaccine development. The diverse nature and complexity of multivalent carbohydrate–protein interactions have been the impetus toward the syntheses of glycodendrimers. Since their inception in 1993, chemical strategies toward glycodendrimers have constantly evolved into highly sophisticated methodologies. This review constitutes the first part of a series of papers dedicated to the design, synthesis, and biological applications of heterofunctional glycodendrimers. Herein, we highlight the most common synthetic approaches toward these complex molecular architectures and present modern applications in nanomolecular therapeutics and synthetic vaccines. 相似文献
148.
Leila Moura Mark Gilmore Samantha K. Callear Tristan G. A. Youngs 《Molecular physics》2019,117(22):3364-3375
149.
A new high efficient and green protocol for the preparation of dihydropyrimido[4,5‐b]quinolinetrione derivatives using magnetically solid acid catalyst was presented. High performance solid acid catalyst was prepared through a three‐step reaction. Firstly, CoFe2O4 nano particles were synthesized using co‐precipitation method. In second step, CoFe2O4 nano particles were coated with SiO2 shell through treatment with tetraethyl orthosilicate (CoFe2O4@SiO2). Finaly, CoFe2O4@SiO2 was modified with polyphosphoric acid (CoFe2O4@SiO2/PPA) in a simple manner. Green reusable catalyst was characterized in details using FTIR, VSM, TEM, FESEM, EDX and used as catalyst for the synthesis of dihydropyrimido[4,5‐b]quinolinetrione derivatives. Reaction was performed under ultrasonic irradiation as green, effective and mild conditions and products were achieved in high to excellent yields. Green and eco‐friendly conditions, short reaction times with high yield of products in addition to easy workup are some merits of presented method. 相似文献
150.