全文获取类型
收费全文 | 640篇 |
免费 | 47篇 |
国内免费 | 5篇 |
专业分类
化学 | 348篇 |
晶体学 | 2篇 |
力学 | 17篇 |
数学 | 56篇 |
物理学 | 148篇 |
无线电 | 121篇 |
出版年
2023年 | 10篇 |
2022年 | 27篇 |
2021年 | 37篇 |
2020年 | 29篇 |
2019年 | 34篇 |
2018年 | 29篇 |
2017年 | 20篇 |
2016年 | 32篇 |
2015年 | 22篇 |
2014年 | 32篇 |
2013年 | 51篇 |
2012年 | 58篇 |
2011年 | 43篇 |
2010年 | 29篇 |
2009年 | 34篇 |
2008年 | 26篇 |
2007年 | 23篇 |
2006年 | 10篇 |
2005年 | 14篇 |
2004年 | 10篇 |
2003年 | 12篇 |
2002年 | 13篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1968年 | 5篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有692条查询结果,搜索用时 93 毫秒
21.
R. Dylewicz A. Z. Khokhar R. Wasielewski P. Mazur F. Rahman 《Applied physics. B, Lasers and optics》2012,107(2):393-399
We describe the fabrication and characterization of a randomly etched gallium nitride (GaN) surface for enhancing light extraction from light-emitting diodes. Our technique uses silica spheres as nano-targets in a sputter-etch process and produces a fine-grained surface with features around 35 nm. The textured surface layer acts as a graded refractive index layer with antireflection properties. Measurements show that photoluminescence intensity from such treated surfaces on a GaN LED wafer increases 2.2?times over that from pristine surfaces. These findings are also supported by computer modelling studies described here. 相似文献
22.
23.
24.
Mudaris N. Dimukhametov Vladimir F. Mironov Dmitry B. Krivolapov Igor A. Litvinov Rashid Z. Musin 《Mendeleev Communications》2012,22(2):98-100
Keeping of O,O’-bis(2-benzylideneaminophenyl) phenylphosphonite in a CCl4 solution for 50 days resulted in its spontaneous rearrangement into 1,6,7-triphenyl-3,4:9,10-dibenzo-2,11-dioxa-5,8-diaza-1-phosphatricyclo[6.3.0.01,5]undeca-3,9-diene, a representative of spirophosphoranes with P–N bonds. 相似文献
25.
Navkiran Kaur Mansimran Khokhar Vaibhav Jain P. V. Bharatam Rajat Sandhir Rupinder Tewari 《Applied biochemistry and biotechnology》2013,171(2):417-436
Emergence of the multidrug-resistant pathogens has rendered the current therapies ineffective thereby, resulting in the need for new drugs and drug targets. The accumulating protein sequence data has initiated a drift from classical drug discovery protocols to structure-based drug designing. In the present study, in silico subtractive genomics approach was implemented to find a set of potential drug targets present in an opportunist bacterial pathogen, Acinetobacter baumannii (A. baumannii). Out of the 43 targets identified, further studies for protein model building and lead-inhibitor identification were carried out on two cell-essential targets, MurA and MurB enzymes (of A. baumannii designated as MurAAb and MurBAb) involved in the peptidoglycan biosynthesis pathway of bacteria. The homology model built for each of them was further refined and validated using various available programs like PROCHECK, Errat, ProSA energy plots, etc. Compounds showing activity against MurA and MurB enzymes of other organisms were collected from the literature and were docked into the active site of MurAAb and MurBAb enzymes. Three inhibitors namely, T6361, carbidopa, and aesculin, showed maximum Glide score, hydrogen bonding interactions with the key amino acid residues of both the enzymes and acceptable ADME properties. Furthermore, molecular dynamics simulation studies on MurAAb–T6361 and MurBAb–T6361 complexes suggested that the ligand has a high binding affinity with both the enzymes and the hydrogen bonding with the key residues were stable in the dynamic condition also. Therefore, these ligands have been propsed as dual inhibitors and promising lead compounds for the drug design against MurAAb and MurBAb enzymes. 相似文献
26.
Ahmad Alshammari Naif Alarifi Marzook Alshammari Manzar Sohail Rashid Altamimi 《Journal of Saudi Chemical Society》2019,23(7):999-1005
The development of base metal catalysts for industrially important reactions continues to be an important goal of catalysis research. Herein, the effects of pyrolysis temperature on the textural, structural, surface, magnetics properties and catalytic properties of silica-supported nickel nanoparticles (NiNPs) were thoroughly investigated. Mono-dispersed NiNPs encapsulated in graphitic shells were first successfully obtained and were characterized using a variety of methods such as BET surface area measurement, CO-pulse chemisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HR-TEM), and superconducting quantum interference device (SQUID) measurement. The findings showed that all catalysts’ properties were considerably altered with change in pyrolysis temperature. Hydrogenation of diphenylacetylene was then selected as the model reaction for the evaluation of the catalytic performance of the graphitic-shelled NiNPs. After testing, pyrolysis of a nickel at 800 °C (catalyst A) displayed tremendous activity and selectivity to produce >94% of stilbene with selectivities of 99% for the Z-isomer. 相似文献
27.
28.
Marina Yamamoto Raynbird Dr. Shaista S. Khokhar Dr. Daniel Neef Dr. Gareth J. S. Evans Prof. Dr. Thomas Wirth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(9):3008-3012
Ajoene is a compound found in garlic extracts exhibiting a large range of biological activity. Novel ajoene analogues have been prepared in the search of compounds with superior bioactivity. Modifications include the alteration of the sulfoxide, the central alkene and the terminal allyl groups. 相似文献
29.
Studies on the Interaction of Some Biologically Significant Radical Scavengers on Metal‐Ion Catalyzed Phloroglucinol‐Based Chemical Oscillator
下载免费PDF全文
![点击此处可从《国际化学动力学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The response of the Ce(III)‐catalyzed phloroglucinol (1,3,5‐trihydroxybenzene)‐based Belousov Zhabotinsky system to the addition of various antioxidants (ascorbic acid, glutathione, inosine, N‐acetylcysteine) is monitored at 30°C under stirred batch conditions. This method is convenient and has good sensitivity for the determination of these antioxidants. The addition of these antioxidants to the BZ mixture influences the oscillatory parameter (number of oscillations) to an extent that depends on the concentration of the antioxidant. The experimental results have shown that the number of oscillations decrease on increasing the concentration of antioxidant. The calibration plots show a linear relationship (R2 = 0.98 for ascorbic acid and glutathione and R2 = 0.99 for inosine and N‐acetylcysteine) between the number of oscillations and the [antioxidant] over the concentration range of 0.0125‐0.5, 0.05‐0.2, 0.025‐0.1, and 0.1‐0.5 mol L?1 with detection limits 6.9 × 10?5, 2.762 × 10?4, 1.381 × 10?4, and 5.524 × 10?4 mol L?1 for ascorbic acid, glutathione, inosine, and N‐acetylcysteine, respectively. Some aspects of the mechanism of these antioxidants on the BZ system have been discussed. 相似文献
30.