全文获取类型
收费全文 | 212篇 |
免费 | 17篇 |
国内免费 | 3篇 |
专业分类
化学 | 182篇 |
力学 | 4篇 |
数学 | 21篇 |
物理学 | 25篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 11篇 |
2020年 | 9篇 |
2019年 | 12篇 |
2018年 | 4篇 |
2017年 | 12篇 |
2016年 | 16篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 23篇 |
2012年 | 19篇 |
2011年 | 19篇 |
2010年 | 12篇 |
2009年 | 10篇 |
2008年 | 12篇 |
2007年 | 12篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1998年 | 1篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1964年 | 2篇 |
排序方式: 共有232条查询结果,搜索用时 31 毫秒
201.
Nima Aliakbarinodehi Irene Taurino Jagdale Pravin Alberto Tagliaferro Gianluca Piccinini Giovanni De Micheli Sandro Carrara 《Chemical Papers》2015,69(1):134-142
The aim of this work was to demonstrate that various types of nanostructures provide different gains in terms of sensitivity or detection limit albeit providing the same gain in terms of increased area. Commercial screen printed electrodes (SPEs) were functionalized with 100 µg of bismuth oxide nanoparticles (Bi2O3 NPs), 13.5 µg of gold nanoparticles (Au NPs), and 4.8 µg of multi-wall carbon nanotubes (MWCNTs) to sense hydrogen peroxide (H2O2). The amount of nanomaterials to deposit was calculated using specific surface area (SSA) in order to equalize the additional electroactive surface area. Cyclic voltammetry (CV) experiments revealed oxidation peaks of Bi2O3 NPs, Au NPs, and MWCNTs based electrodes at (790 ± 1) mV, (386 ± 1) mV, and (589 ± 1) mV, respectively, and sensitivities evaluated by chronoamperometry (CA) were (74 ± 12) µA mM?1 cm?2, (129 ± 15) ±A mM?1 cm?2, and (54 ± 2) ±A mM?1 cm?2, respectively. Electrodes functionalized with Au NPs showed better sensing performance and lower redox potential (oxidative peak position) compared with the other two types of nanostructured SPEs. Interestingly, the average size of the tested Au NPs was 4 nm, under the limit of 10 nm where the quantum effects are dominant. The limit of detection (LOD) was (11.1 ± 2.8) ±M, (8.0 ± 2.4) ±M, and (3.4 ± 0.1) ±M for Bi2O3 NPs, Au NPs, and for MWCNTs based electrodes, respectively. 相似文献
202.
The supramolecular palladium dithiolate complexes, [Pd2(dppe)2{S(C6H4)nS}]2(OTf)4 and [Pd2(dppe)2(SCH2C6H4CH2S)]4(OTf)8 (dppe = 1,2-bis(diphenylphosphino)ethane) has been investigated as highly stable and robust catalysts in Heck C-C coupling reactions. The arylation of butyl acrylate and styrene with various aryl bromides under optimized catalytic systems, showed excellent yield and turnover number (410,000) of the products. The tetranuclear complexes showed slightly higher catalytic activity than the octanuclear complex. 相似文献
203.
Vandana A. Mooss Abhijit A. Bhopale Pravin P. Deshpande Anjali A. Athawale 《Chemical Papers》2017,71(8):1515-1528
In the present work, a set of polyaniline–graphene oxide (PANI–GO) nanocomposites which exhibit superior properties in terms of shelf life, processability and conductivity due to the synergistic effect of GO and PANI, have been synthesized by varying the concentration of highly non-conducting GO with respect to aniline. The obtained materials were characterized by UV–Vis, FTIR, XRD, Raman, TGA as well as FESEM, TEM analysis. The results reveal that nanocomposites show better dispersibility, crystallinity, thermal stability, and conductivity. Further, the synthesized composites have been tested for their anti-corrosion properties. The potentiodynamic results reveal that PANI nanocomposites with 1% GO exhibited long-term anti-corrosion behavior with a corrosion rate of 6.5 × 10?5 mm year?1, which is much lower than its individual components and commercial-grade red oxide. Also, it possesses highest impedance modulus ~33 kΩ cm2 and real impedance ~32 kΩ cm2, maximum coating resistance ~14.81 × 103 Ω cm2 and minimum coating capacitance after 96 h of immersion in 3.5% mass NaCl than those exhibited by all other coated samples. Higher concentration of GO could not retard the corrosion rate confirming that hydrophilicity of GO play an important role in the redox mechanism of PANI. 相似文献
204.
Pravin Shinde Bhagavatula L. V. Prasad 《Particle & Particle Systems Characterization》2021,38(12):2100185
It is demonstrated that the uptake and release of hydrophobic drugs/dyes by mesoporous silica nanoparticles (MSN) is critically dependent on the functional groups present on their outer surfaces. For this, amphifunctional MSNs are synthesized, possessing hydrophobic pores and hydrophilic functional groups on the outer surface. Further, the outer surface is modified with a different chain length of molecules, e.g., propargyl alcohol, triethylene glycol, and PEG (2000) via azide–alkyne click chemistry. The effect of these different surface functional groups on uptake of drug/dye is demonstrated with Nile red, proflavine (free base form), and rhodamine 6G. The uptake of these molecules is found to be inversely proportional to the bulkiness of surface functionality. To counter this effect, an alternate method of loading is proposed and demonstrated. Finally, the effect of these different functional groups on the release of loaded drug proflavine is studied, which supports the hypothesis that bulkier outer surface groups also hinder the release of drugs loaded in the porous MSN. 相似文献
205.
Mohsin Ahmad Bhat Arkaprabha Konar Pravin P. Ingole Altaf Hussain Pandith 《Journal of Physical Organic Chemistry》2012,25(12):1243-1246
Herein, we report our observations on voltammetric investigations about the redox behaviour of para‐nitrotoluene, 1,4‐benzoquinone and ferrocene, aimed at exploring the unusual aspects of ion‐pairing phenomena in imidazolium‐based room temperature ionic liquids (RTILs). Our observations indicate that the stabilization of electrogenerated ion/radical ion intermediates depends upon the potential of the working electrode and the overall composition of RTILs. In light of observed relative trends and quantum mechanical calculations, we propose that the ion‐pair stabilization of electrogenerated charged species in RTILs is closely related to the structural organization and composition of electrode/RTIL interface. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
206.
We describe here an efficient, rapid and selective method for the conversion of nitriles in to their corresponding amides in the presence of PEG-400, aqueous sodium hydroxide system under microwave irradiation. 相似文献
207.
Shirude PS Gillies ER Ladame S Godde F Shin-Ya K Huc I Balasubramanian S 《Journal of the American Chemical Society》2007,129(39):11890-11891
208.
Worldwide, the research on advanced materials for energy storage devices has drawn greater attention. Numerous works on different energy storage materials has been reported and still continuing. Among the energy storage devices, electrochemical supercapacitors (ESs) are one of the most investigated topics. The globalization and increasing demand of smart and flexible devices has forced the current research to develop low-cost, high-energy density and stable ESs. In this regard, metal sulfides (MSs)–based materials have been envisioned for ESs applications owing to their unique and promising properties. Recently, several research articles have been published on MSs-based electrodes for ESs with enhanced performances. This review presents a brief survey on such recent developments towards synthesis of MSs and their use as an efficient electrode material in ESs. The challenges and future aspect involved with MSs to develop and establish it as a promising energy storage material are also discussed. 相似文献
209.
P. Veeraraghavan Ramachandran Pravin D. Gagare Paul Clark 《Tetrahedron letters》2010,51(24):3167-4082
A variety of primary, secondary, and tertiary amines were prepared in 84-95% yields using ammonia borane for the reductive amination of aldehydes and ketones in the presence of titanium isopropoxide. 相似文献
210.
A simple Cu/Al-HT catalyzed amination of aryl chlorides with primary and secondary aromatic amines has been developed. This ligand-free heterogeneous Cu/Al-HT catalyst, in conjunction with base, also efficiently works for the amination of aryl chlorides with cycloalkylamines. This method tolerates a variety of functional groups and does not require an expensive additive. 相似文献