全文获取类型
收费全文 | 386篇 |
免费 | 7篇 |
国内免费 | 3篇 |
专业分类
化学 | 182篇 |
晶体学 | 1篇 |
力学 | 30篇 |
数学 | 121篇 |
物理学 | 62篇 |
出版年
2022年 | 10篇 |
2021年 | 14篇 |
2020年 | 10篇 |
2019年 | 6篇 |
2018年 | 14篇 |
2017年 | 10篇 |
2016年 | 17篇 |
2015年 | 12篇 |
2014年 | 14篇 |
2013年 | 39篇 |
2012年 | 22篇 |
2011年 | 33篇 |
2010年 | 21篇 |
2009年 | 16篇 |
2008年 | 21篇 |
2007年 | 15篇 |
2006年 | 16篇 |
2005年 | 19篇 |
2004年 | 13篇 |
2003年 | 10篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1940年 | 2篇 |
排序方式: 共有396条查询结果,搜索用时 0 毫秒
161.
Hossni Ziyat My Youssef Ait Itto Mustapha Ait Ali Abdellah Karim Abdelkhalek Riahi Jean‐Claude Daran 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(2):o90-o93
The two new gem‐dihalogenocyclopropanes (1′S,3R)‐3‐(2′,2′‐dichloro‐1′‐methylcyclopropyl)‐6‐oxoheptanoic acid, C11H16Cl2O3, (2), and (1′S,3R)‐3‐(2′,2′‐dibromo‐1′‐methylcyclopropyl)‐6‐oxoheptanoic acid, C11H16Br2O3, (3), are isostructural. Both present two stereogenic centers at C1′ and C3. The absolute configuration was determined by X‐ray methods. The cyclopropyl rings are unsymmetrical, the shortest bond being distal with respect to the alkyl‐substituted C atom. 相似文献
162.
Hydrogen bond stretching force constants in crystals of imidazole, urea and cyanuric acid are calculated using both a modified CNDO/2 method and a constrained least squares fitting of interatomic pair potentials to the lattice vibrations. Results show that the modified CNDO/2 method gives closer agreement with the experimentally derived force constants than the normal CNDO/2 parameterization. 相似文献
163.
164.
Mohammed Berkani Mustapha Sarih Hassan Zariouh 《Mediterranean Journal of Mathematics》2011,8(3):399-409
We study the new properties (b) and (gb), which we had introduced in [13], for an operator having the SVEP on the complement of distinguished parts of its spectrum. Classes of operators are considered as illustrating examples. 相似文献
165.
Hicham Hassoun Taibi Lamhasni Salim Foudeil Abdelmajid El Bakkali Saadia Ait Lyazidi Mustapha Haddad M’barek Choukrad Mohamed Hnach 《Journal of fluorescence》2017,27(5):1633-1642
The present work relates to the creation/extension of a database of Total Excitation-Emission and Total Synchronous Fluorescence Matrices (TEEMs and TSFMs) along with optimal Synchronous Fluorescence Spectra (SFS) to fingerprint pesticides widely used in Morocco. This spectrometric multi-component fingerprinting may permit the direct detection of pesticides persisting in soil or water. The objective of the current investigation is to detect four pesticide remains in agricultural soils by applying the spectrometric fingerprinting results. They are the commercial: i) insecticide Axlera 5G (carbamate), ii) fungicide Orsalis 5% SC (triazole), iii) insecticide Force 0,5 G (pyrethrinoid) and iv) insecticide Proclaim 05 SG (non-assigned). The agricultural plantations monitored are located in the great agricultural Doukkala region at the western Atlantic side of Morocco, where these chemicals are in large sale and use. 相似文献
166.
Premaditya Chhetri Dieter Ackermann Hartmut Backe Michael Block Bradley Cheal Christoph Emanuel Düllmann Julia Even Rafael Ferrer Francesca Giacoppo Stefan Götz Fritz Peter Heßberger Oliver Kaleja Jadambaa Khuyagbaatar Peter Kunz Mustapha Laatiaoui Felix Lautenschläger Werner Lauth Enrique Minaya Ramirez Andrew Kishor Mistry Sebastian Raeder Calvin Wraith Thomas Walther Alexander Yakushev 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2017,71(7):195
167.
Activated alkenes and dienes are converted into the corresponding alkenone in excellent yields (>90%). In aqueous acetonitrile, the transformations are catalyzed by 2,2,6,6-tetramethyl-1-oxopiperidinium (TEMPO+) in the presence of water and 2,6-lutidine. TEMPO+ cations were regenerated electrochemically from the radical parent (TEMPO) at a vitreous carbon anode. 相似文献
168.
169.
Mustapha C. Mandewale Bapu Thorat Y. Nivid Ram Jadhav Aarti Nagarsekar Ramesh Yamgar 《Journal of Saudi Chemical Society》2018,22(2):218-228
The quinoline hydrazone ligands were synthesized through multi-step reactions. The 2-hydroxy-3-formylquinoline derivatives (1a–1c) were prepared from acetanilide derivatives as starting materials using Vilsmeier–Haack reaction. Then the condensation of 2-hydroxy-3-formylquinoline derivatives with hydrazide derivatives (2a–2c) yielded quinoline hydrazone ligands (3a–3i). The synthesis of a new series of Zn(II) complexes carried out by refluxing with these quinoline hydrazone ligands (3a–3i) is reported. The molecular structures of the ligands (3a–3i) and the Zn complexes were characterized by elemental analysis and spectral studies like FT-IR, 1H and 13C NMR, MS, UV–Visible and fluorescence. The preliminary results of antituberculosis study showed that most of the Zn(II) complexes 4a–4i demonstrated very good antituberculosis activity while the ligands 3a–3i showed moderate activity. Among the tested compounds 4e and 4g were found to be most active with minimum inhibitory concentration (MIC) of 8.00 μM and 7.42 μM respectively against Mycobacterium tuberculosis (H37 RV strain) ATCC No-27294 which is comparable to “first and second line” drugs used to treat tuberculosis. 相似文献
170.
We determine upper bounds on the ratios of several domination parameters in trees. 相似文献