全文获取类型
收费全文 | 1022篇 |
免费 | 50篇 |
国内免费 | 18篇 |
专业分类
化学 | 864篇 |
晶体学 | 7篇 |
力学 | 15篇 |
数学 | 62篇 |
物理学 | 142篇 |
出版年
2024年 | 1篇 |
2023年 | 13篇 |
2022年 | 53篇 |
2021年 | 39篇 |
2020年 | 59篇 |
2019年 | 64篇 |
2018年 | 79篇 |
2017年 | 62篇 |
2016年 | 72篇 |
2015年 | 52篇 |
2014年 | 68篇 |
2013年 | 117篇 |
2012年 | 87篇 |
2011年 | 80篇 |
2010年 | 52篇 |
2009年 | 44篇 |
2008年 | 31篇 |
2007年 | 16篇 |
2006年 | 15篇 |
2005年 | 15篇 |
2004年 | 7篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 2篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1992年 | 3篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有1090条查询结果,搜索用时 0 毫秒
141.
Nanocrystalline TiO2, via green combustion synthesis,as an efficient and reusable catalyst for the preparation of 1,8‐dioxooctahydroxanthenes and 1,8‐dioxodecahydroacridines 下载免费PDF全文
Nanocrystalline TiO2 is synthesized using a green combustion method and used as a recyclable catalyst for the one‐pot multicomponent synthesis of 1,8‐dioxodecahydroacridines and 1,8‐dioxooctahydroxanthenes, under solvent‐free conditions. This method is mild, environmentally friendly, inexpensive and highly effective for obtaining good to excellent yields of the products. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
142.
143.
Issa Yavari S. Zahra Sayyed-Alangi Maryam Sabbaghan Rahimeh Hajinasiri Nasir Iravani 《Monatshefte für Chemie / Chemical Monthly》2008,139(9):1025-1028
An efficient one-pot synthesis of functionalized thioureas is described via three-component reaction of benzoyl isothiocyanates, secondary amines, and alkyl propiolates in the presence of triphenylphosphine
(20 mol%).
Correspondence: Issa Yavari, Chemistry Department, Tarbiat Modares University, PO Box 14115-175, Tehran, Iran 相似文献
144.
A series of photoactive polyamides (PAs) containing acetoxynaphthalamide side chain with inherent viscosities of 0.27–0.56 dl g?1 were prepared by the direct polycondensation reaction of the 5‐(3‐acetoxynaphthoylamino)isophthalic acid with various commercially available diamines by means of triphenyl phosphite (TPP) and pyridine (Py) in the presence of calcium chloride and N‐methyl‐2‐pyrrolidone (NMP) under microwave irradiation and conventional heating conditions. Most of the resulting PAs are soluble in strong polar solvents such as N,N‐dimethylformamide (DMF), N,N‐dimethylacetamide, and NMP. Thermo‐gravimetric analysis (TGA) showed that polymers are thermally stable, 10% weight loss temperatures in excess of 320 and 378°C, and char yields at 600°C in nitrogen higher than 60%. These macromolecules exhibited maximum UV‐Vis absorption at 265 and 300 nm in a DMF solution. Their photoluminescence in the DMF solution demonstrated fluorescence emission maxima around 361 and 427 nm for all of the PAs. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
145.
Ali Naghipour Zahra Haji Ghasemi David Morales-Morales Juan M. Serrano-Becerra Craig M. Jensen 《Polyhedron》2008
The asymmetric PCP pincer ligand [C6H4-1-(CH2PPh2)-3-(CH(CH3)PPh2)] (4) has been synthesized in a facile manner in three simple steps in high yield. Metallation of PCP pincer ligand (4) with [Pd(COD)Cl2] affords complex [PdCl{C6H3-2-(CH2PPh2)-6-(CH(CH3)PPh2)}] (7) in good yield. 相似文献
146.
Zahra Siroos Mohammad H. Mosslemin 《Phosphorus, sulfur, and silicon and the related elements》2020,195(10):877-880
AbstractReaction between arylidenemalononitriles and dimethyl acetylenedicarboxylate in the presence of KSeCN at room temperature provided a simple and efficient one-pot route for the synthesis of highly functionalized selenophenes. The reaction is characterized by mild conditions, short reaction time, and tolerance to various functional groups. 相似文献
147.
Sebastian Grieger Beata M. Szydowska Vaishnavi J. Rao Eva Steinmann Marcus Dodds Zahra Gholamvand Georg S. Duesberg Jana Zaumseil Claudia Backes 《Angewandte Chemie (International ed. in English)》2020,59(33):13785-13792
In recent years, various functionalization strategies for transition‐metal dichalcogenides have been explored to tailor the properties of materials and to provide anchor points for the fabrication of hybrid structures. Herein, new insights into the role of the surfactant in functionalization reactions are described. Using the spontaneous reaction of WS2 with chloroauric acid as a model reaction, the regioselective formation of gold nanoparticles on WS2 is shown to be heavily dependent on the surfactant employed. A simple model is developed to explain the role of the chosen surfactant in this heterogeneous functionalization reaction. The surfactant coverage is identified as the crucial element that governs the dominant reaction pathway and therefore can severely alter the reaction outcome. This study shows the general importance of the surfactant choice and how detrimental or beneficial a certain surfactant can be to the desired functionalization. 相似文献
148.
Soodabeh Davaran Mohammad Sadeghinia Zahra Jamalpoor Vahideh Raeisdasteh Hokmabad Mehdi Doosti-Telgerd Ansar Karimian Zahra Sadeghinia Javad Khalilifard Akram keramt Farzad Moradikhah Ali Sadeghinia 《Electrophoresis》2020,41(12):1081-1094
Microfluidic system, or lab-on-a-chip, has grown explosively. This system has been used in research for the first time and then entered in the clinical section. Due to economic reasons, this technique has been used for screening of laboratory and clinical indices. The microfluidic system solves some difficulties accompanied by clinical and biological applications. In this review, the interpretation and analysis of some recent developments in microfluidic systems in biomedical applications with more emphasis on tissue engineering and cancer will be discussed. Moreover, we try to discuss the features and functions of microfluidic systems. 相似文献
149.
One of the commonly used methods to synthesize furans is the three-component reaction among aromatic aldehyde, arylamine, and acetylenedicarboxylate. The main advantages of this work are easy reaction work-up, short reaction time, high yield and easy recyclability, reusability of the catalyst. And also basalt fiber applications are surely innovative in many industrial and economic fields, because of its good mechanical, chemical and thermal performances. 相似文献
150.
The electronic (energy gap and work function) as well as electrical properties (dipole moment, polarizability, and first hyperpolarizabilities) of the first-row transition metals decorated C24N24 cavernous nitride fullerene were explored using DFT calculations. The transition metals are decorated at N4 cavity of C24N24 fullerene. According to our spin polarized computations, the most stable spin state monotonically increases to sextet for Mn@C24N24 and thereafter dropped off gradually to singlet state for Zn@C24N24 system. The findings demonstrate that transition metals can remarkably decrease the HOMO-LUMO energy gap and work function values up to 63% and 21% of bare C24N24, respectively. As can be seen, when the Sc and Ti metals are located above the N4 cavity of fullerene, systems of enhanced static hyperpolarizabilities (β0) are delivered. These findings might provide an effective strategy to design high performance eletcro-optical materials based on carbon- nitride fullerene. 相似文献