全文获取类型
收费全文 | 378篇 |
免费 | 18篇 |
国内免费 | 1篇 |
专业分类
化学 | 276篇 |
晶体学 | 8篇 |
力学 | 21篇 |
数学 | 35篇 |
物理学 | 57篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 17篇 |
2020年 | 7篇 |
2019年 | 6篇 |
2018年 | 13篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 15篇 |
2013年 | 16篇 |
2012年 | 25篇 |
2011年 | 21篇 |
2010年 | 13篇 |
2009年 | 21篇 |
2008年 | 18篇 |
2007年 | 29篇 |
2006年 | 21篇 |
2005年 | 28篇 |
2004年 | 21篇 |
2003年 | 19篇 |
2002年 | 21篇 |
2001年 | 6篇 |
2000年 | 13篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 9篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1979年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有397条查询结果,搜索用时 250 毫秒
391.
Abstract 3-[(Naphthalen-2-yl) methyl]isocoumarin was synthesized by the reaction of homophthalic acid with 2-(naphthalen-2-yl)acetyl
chloride at elevated temperature and its crystal structure has been determined (C20H14O2), Mr = 286.31, a = 13.704(3), b = 7.356(4), c = 7.042(7) ?, β = 99.21(3)°, space group Pc, Z = 2, and V = 700.7(8) ?3. The isocoumarin and the naphthalene ring systems are individually planar and the dihedral angle between the mean planes
of these two ring systems is 70.05(8)°.
Graphical Abstract Synthesis and crystal structure of 3-[(Naphthalen-2-yl)methyl]isocoumarin
Aamer Saeed, Junmei Liang, Masood Parvez
The synthesis and crystal structure of a novel isocoumarin, 3-[(naphthalen-2-yl)methyl]isocoumarin has been presented.
相似文献
392.
Kulsoom Zahara Yamin Bibi Saadia Masood Sobia Nisa Abdul Qayyum Muhammad Ishaque Khurram Shahzad Waseem Ahmed Zahid Hussain Shah Hameed Alsamadany Seung-Hwan Yang Gyuhwa Chung 《Molecules (Basel, Switzerland)》2021,26(19)
Gui Zhen Cao is an herbal formulation that has been documented in Chinese traditional medicine as a remedy for diarrhea, dysentery, inflammation, and toxicity. The sources of this formulation (Bidens pilosa L., Bidens biternata (Lour.) Merr. & Sherff, Bidens bipinnata L.) are also listed in ethnomedicinal reports all over the world. In this study, all these plants are tested for in vitro anticandida activity. A quantitative evaluation of the phytochemicals in all these plants indicated that their vegetative parts are rich in tannins, saponins, oxalates, cyanogenic glycoside and lipids; moreover, the roots have high percentages of alkaloids, flavonoids, and phenols. The results indicated significant anticandida activity, especially for the hexane extract of B. bipinnata leaves which inhibited C. albicans (42.54%), C. glabrata (46.98%), C. tropicalis (50.89%), C. krusei (40.56%), and C. orthopsilosis (50.24%). The extract was subjected to silica gel chromatography and 220 fractions were obtained. Purification by High Performance Liquid Chromatography with Diode-Array Detection (HPLC–DAD) and Gas Chromatography tandem Mass Spectrometry (GC-MS/MS) analysis led to the identification of two anticandida compounds: dehydroabietic and linoleic acid having an inhibition of 85 and 92%, respectively. 相似文献
393.
394.
Mohammad Z. Ahmed Fahd A. Nasr Wajhul Qamar Omar M. Noman Javed Masood Khan Abdullah A. Al-Mishari Ali S. Alqahtani 《Molecules (Basel, Switzerland)》2021,26(24)
Janerin is a cytotoxic sesquiterpene lactone that has been isolated and characterized from different species of the Centaurea genus. In this study, janerin was isolated form Centaurothamnus maximus, and its cytotoxic molecular mechanism was studied in THP-1 human leukemic cells. Janerin inhibited the proliferation of THP-1 cells in a dose-dependent manner. Janerin caused the cell cycle arrest at the G2/M phase by decreasing the CDK1/Cyclin-B complex. Subsequently, we found that janerin promoted THP-1 cell death through apoptosis as indicated by flow cytometry. Moreover, apoptosis induction was confirmed by the upregulation of Bax, cleaved PARP-1, and cleaved caspase 3 and the downregulation of an anti-apoptotic Bcl-2 biomarker. In addition, immunoblotting indicated a dose dependent upregulation of P38-MAPK and ERK1/2 phosphorylation during janerin treatment. In conclusion, we have demonstrated for the first time that janerin may be capable of inducing cell cycle arrest and apoptosis through the MAPK pathway, which would be one of the mechanisms underlying its anticancer activity. As a result, janerin has the potential to be used as a therapeutic agent for leukemia. 相似文献
395.
The newly discovered crystal structures of CH3(OCH2CH2)OCH3(LiCF3SO3)2, monoglyme:(LiTf)2, and CH3(OCH2CH2)3OCH3(LiCF3SO3)2, triglyme:(LiTf)2, are briefly described. The coordination of lithium cations and the CF3SO3− anions in these structures is compared with the cation and anion coordination in the crystalline phase of high molecular weight P(EO)3LiCF3SO3. Comparison is also made with the previously reported crystalline phase of CH3(OCH2CH2)2OCH3LiCF3SO3, diglyme:LiTf. A tendency to form trans-gauche-trans conformations for the bond order -O-C-C-O- is noted in adjacent ethylene oxide sequences interacting with a five-coordinate lithium ion. 相似文献
396.
397.