全文获取类型
收费全文 | 455篇 |
免费 | 37篇 |
国内免费 | 2篇 |
专业分类
化学 | 373篇 |
晶体学 | 8篇 |
力学 | 3篇 |
数学 | 34篇 |
物理学 | 76篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 15篇 |
2020年 | 17篇 |
2019年 | 8篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 16篇 |
2015年 | 16篇 |
2014年 | 19篇 |
2013年 | 31篇 |
2012年 | 31篇 |
2011年 | 47篇 |
2010年 | 33篇 |
2009年 | 22篇 |
2008年 | 29篇 |
2007年 | 25篇 |
2006年 | 33篇 |
2005年 | 19篇 |
2004年 | 23篇 |
2003年 | 14篇 |
2002年 | 12篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 1篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1988年 | 1篇 |
1983年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1896年 | 1篇 |
排序方式: 共有494条查询结果,搜索用时 0 毫秒
51.
A novel bifunctional molecule 1 by a combination of 1,3-alternate calix[4]-crown-5 and triarylborane moieties through alkynyl linkers has been designed and synthesized. Compound 1 shows intense fluorescence with a photoluminescence quantum yield of 0.70 in CH(2)Cl(2) solution and can serve as a bifunctional luminescent probe for potassium and fluoride ions with high sensitivity and selectivity. 相似文献
52.
Synthesis of Unsymmetric Bipyridine–PtII–Alkynyl Complexes through Post‐Click Reaction with Emission Enhancement Characteristics and Their Applications as Phosphorescent Organic Light‐Emitting Diodes 下载免费PDF全文
Dr. Yongguang Li Dr. Daniel Ping‐Kuen Tsang Dr. Carmen Ka‐Man Chan Dr. Keith Man‐Chung Wong Dr. Mei‐Yee Chan Prof. Dr. Vivian Wing‐Wah Yam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(42):13710-13715
Two unsymmetric bipyridine–platinum(II)–alkynyl complexes have been synthesised by a post‐click reaction. These metal complexes are found to exhibit emission enhancement properties. The photoluminescence quantum yield can be significantly increased from 0.03 in solution to 0.72 in solid‐state thin films. Efficient solution‐processable organic light‐emitting diodes have been fabricated by utilizing these complexes as phosphorescent dopants. A high external quantum efficiency of up to 5.8 % has been achieved. 相似文献
53.
Thermal activation of molecularly-wired gold nanoparticles on a substrate as catalyst 总被引:5,自引:0,他引:5
Luo J Jones VW Maye MM Han L Kariuki NN Zhong CJ 《Journal of the American Chemical Society》2002,124(47):13988-13989
The ability to prepare nanostructured metal catalysts requires the ability to control size and interparticle spatial and surface access properties. In this work, we report novel findings of an atomic force microscopic investigation of a controlled thermal activation strategy of gold catalysts nanostructured via molecular wiring or linking on a substrate surface. Gold nanocrystals of approximately 2 nm diameter capped by decanethiolate and wired by 1,9-nonanedithiolate on mica substrates were studied as a model system. By manipulating the activation temperature (200-250 degrees C), the capping/wiring molecules can be removed to produce controllable particle size and interparticle spatial morphology. The electrocatalytic activity of the activated nanostructures toward methanol oxidation, which is of fundamental importance to fuel cell catalysis, has been demonstrated. The novelty of the findings is the viability of a thermal activation strategy of core-shell nanostructured catalysts based on molecularly predefined interparticle spatial properties on a substrate, which upon further investigation may form the basis for spatially controllable nanostructured catalysts. 相似文献
54.
55.
Functionalized platinum(II) terpyridyl alkynyl complexes as colorimetric and luminescence pH sensors 总被引:1,自引:0,他引:1
A series of platinum(II) terpyridyl alkynyl complexes that have been derivatized with basic amino functionalities, [Pt(tpy)(C[triple bond]C-C6H4-NR2-4]X (X = OTf-, R = CH3 1, R = CH2CH2OCH3 2, R = H 3; X = Cl-, R = CH3 4, R = CH2CH2OCH3 5, R = H 6) (tpy = 2,2':6',2' '-terpyridine), have been synthesized and characterized. Their photophysical responses at various acid concentrations were studied. The abilities of the complexes to function as colorimetric and luminescence pH sensors were demonstrated with dramatic color changes and luminescence enhancement upon introduction of acid. 相似文献
56.
De La Rosa Luis B. Reshamwala Sultan Latimer Vivian M. Shawky Bahaa T. Dale Bruce E. Stuart Earnest D. 《Applied biochemistry and biotechnology》1994,(1):483-497
The herbaceous crops that may provide fermentable carbohydrates for production of fuels and chemicals also contain 10–20%
protein. Protein coproduction with biomass-derived fuels and chemicals has important advantages: (1) food and fuel production
can be integrated, and (2) protein is a high-value product that may significantly improve overall process economics. We report
the results of an integrated approach to producing protein and fermentable sugars from one herbaceous species, Coastal Bermudagrass
(CBG). The ammonia fiber explosion (AFEX) process makes possible over 90% conversion of cellulose and hemicellulose to simple
sugars (about 650 mg reducing sugars/g dry CBG) at 5 IU cellulase/g vs < 20% conversion for untreated CBG. The AFEX treatment
also improves protein extraction from CBG; over 80% protein recovery is possible from AFEX-treated CBG vs about 30% recovery
from untreated CBG. 相似文献
57.
58.
Lu XX Tang HS Ko CC Wong JK Zhu N Yam VW 《Chemical communications (Cambridge, England)》2005,(12):1572-1574
The anion-assisted shift of trans-cis isomerization equilibrium of a palladium(II) complex containing acetanilide functionalities brought about by allosteric hydrogen bonding interactions has been established by UV/Vis, 1H NMR, 31P NMR and ESI-MS studies. 相似文献
59.
Manuel Caetano Leonardo Padrino T Hector Gutiérrez Alberto J. Fernández Jimmy Castillo 《Mikrochimica acta》1998,128(3-4):169-175
Trace level vanadium determination is reported using a dual beam thermal lens spectrometer. The thermal lens was generated using an argon ion beam laser (pump beam) which was focused into a sample cuvette. The thermal lens signal (TLs) was monitored with a He-Ne laser beam and a photodiode detector. Multichannel averager software was developed for processing the transient TLs. The optimal set up, ensuring maximum sensitivity and linear calibration graphs was obtained using experimental design techniques. Under optimized conditions, the detection limits for aqueous and ethanol-water (2+3 v/v) and (4+1 v/v) vanadium complex solutions were, respectively, 0.0071 mg/l, 0.0065 and 0.0039 mg/l. 相似文献
60.