全文获取类型
收费全文 | 177篇 |
免费 | 8篇 |
专业分类
化学 | 110篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 21篇 |
物理学 | 16篇 |
无线电 | 35篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 10篇 |
2020年 | 15篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 16篇 |
2015年 | 8篇 |
2014年 | 4篇 |
2013年 | 11篇 |
2012年 | 19篇 |
2011年 | 12篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 8篇 |
2007年 | 8篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 7篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有185条查询结果,搜索用时 0 毫秒
21.
Huynh Le Thanh Nguyen Tran Thi Thuy Dung Nguyen Hoang Hai Au Nguyen Thi Thu Trang Tran Van Man Grag Akhil Le My Loan Phung 《Journal of Solid State Electrochemistry》2018,22(7):2247-2254
Journal of Solid State Electrochemistry - Olivine LiFePO4 (LFP) is a promising cathode material for high-rated lithium-ion batteries. However, olivine faced a severe disadvantage of low... 相似文献
22.
Coupling of liquid chromatography at critical conditions (LCCC) with on-line mass spectrometry (MS) detection was implemented via an electrospray ionization (ESI) interface, using a mobile phase containing the cationizing agent. Critical conditions established for poly(ethylene oxide) were used to characterize a poly(ethylene oxide)/polystyrene block copolymer (PEO-b-PS) in both MS and MS/MS modes. As co-oligomer molecules were successfully separated according to the PS block size, structural information could be reached from simplified MS spectra. The microstructure of this copolymer, synthesized by nitroxide-mediated polymerization, could further be unambiguously characterized in LCCC/ESI-MS/MS experiments since the PS block size could be reached by both the co-oligomer chromatographic behavior and its MS/MS pattern. 相似文献
23.
Nguyen Thi Quynh Trang 《Optimization Letters》2016,10(6):1221-1231
In the previous paper (Optim lett 6:749–762, 2012), under some technical assumptions, we proved that the solution mapping of variational inequalities over perturbed polyhedral convex sets is not Lipschitz-like around points at which the positively linear dependence of the active vectors defining the constraint set is valid. This note shows that the result holds without such assumptions. In addition, for more deeply understanding the results on the Lipschitz-like stability, some examples have been presented. 相似文献
24.
Pham Bich Ngoc Thanh Binh Pham Hai Dang Nguyen Thu Trang Tran Hoang Ha Chu Van Minh Chau 《Natural product research》2016,30(12):1360-1365
One new β-carboline alkaloid 7-methoxy-(9H-β-carbolin-1-il)-(E)-1-propenoic acid (1) together with 9-methoxycanthin-6-one (2) and 9-hydroxycanthin-6-one (3) were isolated from the hairy-root cultures of Eurycoma longifolia. The effects of these compounds on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 cells were investigated. Compound 1 strongly inhibited the production of NO while 2 and 3 having weak or inactive effect. Consistently, compound 1 decreased the expression of cyclooxygenase-2 and inducible nitric oxide synthase. 相似文献
25.
Stéphane Viel Michaël Mazarin Trang N.T. Phan Stefano Caldarelli 《Analytica chimica acta》2009,654(1):45-7878
Block copolymers constitute a fascinating class of polymeric materials that are used in a broad range of applications. The performance of these materials is highly coupled to the physical and chemical properties of the constituting block copolymers. Traditionally, the composition of block copolymers is obtained by 1H NMR spectroscopy on purified copolymer fractions. Specifically, the integrals of a properly selected set of 1H resonances are compared and used to infer the number average molecular weight (Mn) of one of the block from the (typically known) Mn value of the other. As a corollary, compositional determinations achieved on imperfectly purified samples lead to serious errors, especially when isolation of the block copolymer from the initial macro initiator is tedious. This investigation shows that Diffusion Ordered NMR Spectroscopy (DOSY) can be used to provide a way to assess the advancement degree of the copolymerization purification/reaction, in order to optimize it and hence contribute to an improved compositional analysis of the resulting copolymer. To this purpose, a series of amphiphilic polystyrene-b-poly(ethylene oxide) block copolymers, obtained by controlled free-radical nitroxide mediated polymerization, were analyzed and it is shown that, under proper experimental conditions, DOSY allows for an improved compositional analysis of these block copolymers. 相似文献
26.
Bulleigh K Howard A Do T Wu Q Anbalagan V Stipdonk MV 《Rapid communications in mass spectrometry : RCM》2006,20(2):227-232
In this study we used an isotope label, generated in situ, to investigate intramolecular proton migration or scrambling during formation of [b(2)+17+Li](+) products by collision-induced dissociation (CID) of Li(+)-cationized tripeptides. To generate the isotope label, we used a McLafferty-type rearrangement of N-terminally acetylated, C-terminal peptide tert-butyl esters in which all amide positions were exchanged with deuterium. Using a set of small, model peptides, we show that intramolecular proton scrambling occurs during CID, particularly amongst adjacent sites along a peptide backbone, on the time scales employed for low-energy collisional activation in an ion-trap mass spectrometer. 相似文献
27.
Effects of Cu2−xS phase removal on surface potential of Cu2ZnSnS4 thin-films grown by electroplating
Gee Yeong Kim Ju Ri Kim William Jo Kee Doo Lee Jin Young Kim Trang Thi Thu Nguyen Seokhyun Yoon 《Current Applied Physics》2014,14(12):1665-1668
Cu2ZnSnS4 (CZTS) has an optical band gap of 1.4–1.5 eV, which is similar to that of Cu(In,Ga)Se2 (CIGS), and a high absorption coefficient (>104 cm−1) in the visible light region. In previous reports, CIGS thin-film solar cells have been shown to improve the performance of the device since the secondary phase is removed by Potassium cyanide (KCN) etching treatment. Therefore, in this study we applied a KCN etching treatment on CZTS and measured the effects. We confirmed the removal of Cu2−xS via Kelvin probe force microscopy (KPFM) and Raman scattering spectroscopy. The effects of the experiment indicate that we can define with precision the location of the secondary phases, and therefore the control of the secondary phases will be easier and more efficient. Such capabilities could improve the solar cell performance of CZTS thin-films. 相似文献
28.
TM Ton F Himawan JW Chang PW Chan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(38):12020-12027
A method to prepare α,α-acyl amino acid derivatives efficiently by Cu(OTf)(2) +1,10-phenanthroline (1,10-phen)-catalyzed amination of 1,3-dicarbonyl compounds with PhI?NSO(2) Ar is described. The mechanism is thought to initially involve aziridination of the enolic form of the substrate, formed in situ through coordination to the Lewis acidic metal catalyst, by the putative copper-nitrene/imido species generated from the reaction of the metal catalyst with the iminoiodane source. Subsequent ring opening of the resultant aziridinol adduct under the Lewis acidic conditions then provided the α-aminated product. The utility of this method was exemplified by the enantioselective synthesis of a precursor of 3-styryl-2-benzoyl-L-alanine. 相似文献
29.
In recent years, gold nanoparticles have been increasingly utilized as a promising material for biomedical analysis. We report here for the first time the synthesis of ultrasmall gold nanoparticles with core diameter of 1.2 nm functionalized with hydrazide groups and their use in isolation/enrichment of N-glycosylated peptides. Hydrazide-functionalized gold nanoparticles showed excellent stability in biological samples and exhibited a large capacity for peptide capturing. The captured peptides from tested standard glycoproteins were found to be highly specific as determined by Agilent HPLC chip and quadrupole time-of-flight (Q-TOF) mass spectrometer. The hydrazide-functionalized gold nanoparticles were successfully utilized in the isolation of a real proteome complex, which showed that more than 90% of captured product was glycopeptide. These results demonstrate that the ultrasmall gold nanoparticles can be used for a high-throughput analysis platform of glycoproteins. 相似文献
30.
Ultrashort optical pulse generation using a fiber FM laser is presented and analyzed in detail. Fiber FM laser operation is realized using a fiber ring with an internal phase modulator and an erbium-doped fiber amplifier. To compress FM laser pulses, an external dispersive single-mode fiber is employed. Furthermore, by external intensity modulation, the pulse background is removed. The background ratio of the generated ultrashort pulse is calculated and compared with the experimental results. The experimental results show an output optical pulse width of 1.77 ps and a spectral bandwidth of 0.5 THz. 相似文献