全文获取类型
收费全文 | 209篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
化学 | 171篇 |
晶体学 | 2篇 |
力学 | 2篇 |
数学 | 17篇 |
物理学 | 22篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 4篇 |
2013年 | 9篇 |
2012年 | 14篇 |
2011年 | 14篇 |
2010年 | 12篇 |
2009年 | 4篇 |
2008年 | 22篇 |
2007年 | 15篇 |
2006年 | 24篇 |
2005年 | 7篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1980年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有214条查询结果,搜索用时 19 毫秒
121.
Designing a Highly Active Metal‐Free Oxygen Reduction Catalyst in Membrane Electrode Assemblies for Alkaline Fuel Cells: Effects of Pore Size and Doping‐Site Position 下载免费PDF全文
Seonggyu Lee Myounghoon Choun Youngjin Ye Prof. Dr. Jaeyoung Lee Yeongdong Mun Dr. Eunae Kang Jongkook Hwang Young‐Ho Lee Prof. Dr. Chae‐Ho Shin Prof. Dr. Seung‐Hyeon Moon Prof. Dr. Soo‐Kil Kim Prof. Dr. Eunsung Lee Prof. Dr. Jinwoo Lee 《Angewandte Chemie (International ed. in English)》2015,54(32):9230-9234
To promote the oxygen reduction reaction of metal‐free catalysts, the introduction of porous structure is considered as a desirable approach because the structure can enhance mass transport and host many catalytic active sites. However, most of the previous studies reported only half‐cell characterization; therefore, studies on membrane electrode assembly (MEA) are still insufficient. Furthermore, the effect of doping‐site position in the structure has not been investigated. Here, we report the synthesis of highly active metal‐free catalysts in MEAs by controlling pore size and doping‐site position. Both influence the accessibility of reactants to doping sites, which affects utilization of doping sites and mass‐transport properties. Finally, an N,P‐codoped ordered mesoporous carbon with a large pore size and precisely controlled doping‐site position showed a remarkable on‐set potential and produced 70 % of the maximum power density obtained using Pt/C. 相似文献
122.
Using the molecular imprinting approach, we have shown that polyacrylamide-based artificial antibodies against human and bovine hemoglobin have a very high selectivity, as revealed by the free-zone electrophoresis in a revolving capillary. By the same technique we have previously synthesized gel antibodies not only against proteins but also against viruses and bacteria. The synthesis is thus universal, i.e., it has the great advantage of not requiring a modification - or only a slight one - for each particular antigen. The combination synthesis of artificial gel antibodies and electrophoretic analysis reveals small discrepancies in shape and chemical composition not only of proteins, as shown here and in paper Ia, but also of viruses and bacteria, to be illustrated in papers II and III in this series. Upon rehydration, the freeze-dried gel antibodies, selective for human hemoglobin, regain their selectivity. The gel antibodies can repeatedly be used following the removal of the antigen (protein in this study) from the complex gel antibody/antigen by an SDS washing or an enzymatic degradation. 相似文献
123.
Lee HW Cho CS Kang SK Yoo YS Shin JS Ahn SK 《Chemical & pharmaceutical bulletin》2007,55(7):1024-1029
A series of fumagillin analogues containing the C6-substituted cinnamoyl moiety were designed, synthesized, and evaluated for antiangiogenic activity. Among them, 4-hydroxyethoxy-cinnamoyl fumagillol (4a) and 4-hydroxyethoxy-3,5-dimethoxycinnamoyl fumagillol (4d) exhibited more potent anti-proliferation activity in CPAE and HUVEC cells with low cytotoxicity in vitro. These compounds are presently under further pharmacological evaluation studies. 相似文献
124.
125.
Recent applications of capillary isoelectric focusing 总被引:2,自引:0,他引:2
Kilár F 《Electrophoresis》2003,24(22-23):3908-3916
After the advent of capillary isoelectric focusing (CIEF) in the 80's several approaches have been developed in order to use the technique in routine analyses. The recent years showed an extensive increase in the applications of this technique employing its exceptionally high-resolution power. Methodological improvements, as well as hyphenation with other electrophoretic and chromatographic separation procedures, proved the versatility of CIEF in studies of clinically important proteins, recombinant product, cell lysates and other complex mixtures. The combination of CIEF with mass spectrometry detection is one of the major challenges for studying proteomics. This review collected the recent applications of CIEF including innovations in the experimental setup, remedies for the presence of salts in samples, calibration of the pH gradient, carrier ampholyte-free isoelectric focusing, the progress in micropreparation, two-dimensional separations, etc. 相似文献
126.
Three new chalcones, 3′‐carboxymethyl‐4,2′‐dihydroxy‐4′‐methoxychalcone ( 1 ), (±)‐4,2′,4′‐trihydroxy‐3′‐[(3‐hydroxy‐2,2‐dimethyl‐6‐methylenecyclohexyl)methyl]chalcone ( 2 ), and 2′′‐hydroxyangelichalcone ( 3 ), were isolated from the aerial parts of Angelica keiskei (Umbelliferae) together with five known compounds, artocarmitin A ( 4 ), (+)‐cis‐(3′R,4′R)‐methylkhellactone ( 5 ), (?)‐trans‐(3′R,4′S)‐methylkhellactone ( 6 ), 3,4‐dihydroxanthotoxin ( 7 ), and (Z)‐p‐coumaryl alcohol ( 8 ). The known compounds 4 – 8 were identified from A. keiskei for the first time. The structures of 1 – 3 were elucidated by interpreting spectroscopic data including 1D‐ and 2D‐NMR. 相似文献
127.
Youngji Cho Jun-Seok Ha Mina Jung Hyun-Jae Lee Seunghwan Park Jinsub Park Katsushi Fujii Ryuichi Toba Samnyung Yi Gyung-Suk Kil Jiho Chang Takafumi Yao 《Journal of Crystal Growth》2010,312(10):1693-1696
The present study focused on the effect of an intermediate-temperature (IT; ∼900 °C) buffer layer on GaN films, grown on an AlN/sapphire template by hydride vapor phase epitaxy (HVPE). In this paper, the surface morphology, structural quality, residual strain, and luminescence properties are discussed in terms of the effect of the buffer layer. The GaN film with an IT-buffer revealed a relatively lower screw-dislocation density (3.29×107 cm−2) and a higher edge-dislocation density (8.157×109 cm−2) than the GaN film without an IT-buffer. Moreover, the IT-buffer reduced the residual strain and improved the luminescence. We found that the IT-buffer played an important role in the reduction of residual strain and screw-dislocation density in the overgrown layer through the generation of edge-type dislocations and the spontaneous treatment of the threading dislocation by interrupting the growth and increasing the temperature. 相似文献
128.
Ho Sik Kim Ju Young Chung Eun Kyoung Kim Yong Tae Park Young Seuk Hong Man Kil Lee Yoshihisa Kurasawa Atsushi Takada 《Journal of heterocyclic chemistry》1996,33(6):1855-1858
Novel 1H-pyrazolo[3,4-b]quinoxalines (flavazoles) 14, 15 and 1-aryl-3-quinoxalinyl-1,2,4-triazole 17 were synthesized from the ester 11 via various hydrazones 12, 13 and 16 . In the antibacterial screening test of compounds 12–17 , compound 14 showed a relatively high antibacterial activity, wherein the MIC value was 25 μg/ml against Bacillus licheniformis KTCC 21425 and Cellulomonas sp. and 50 μg/ml against Salmonella typhimurium KCTC 1925 and Flavobacterium devolans. 相似文献
129.
H Machner M Betigeri J Bojowald A Budzanowski A Chatterjee J Ernst L Freindl D Frekers W Garske K Grewer A Hamacher J Ilieva L Jarczyk K Kilian S Kliczewski W Klimala D Kolev T Kutsarova J Lieb H Machner A Magiera H Nann L Pentchev HS Plendl D Protić B Razen P Von Rossen BJ Roy R Siudak J Smyrski RV Srikantiah A Strzałkowski R Tsenov K Zwoll 《Pramana》2001,57(2-3):399-416
Total and differential cross sections for the reactions p + d → 3He + m
0 with m=π, η and p + d → 3H+π+ were measured with the GEM detector at COSY for beam momenta between threshold and the maximum of the corresponding baryon
resonance. For both reactions a strong forward-backward asymmetry was found. The data were compared with model calculations.
The aspect of isospin symmetry breaking is studied.
Representing the GEM Collaboration 相似文献
130.
1IntroductionandProblem IteratedFunctionSystems(IFS)theorycanbesaidtobethecontinuationanddevelopment ofdynamicalsystemtheory.DynamicalsystemstheorydealswithiterationofonemapbutIFS theorydealswithiterationofmanymaps. IFStheory’srootwasveryearlybutthebeginningofactivedevelopmentwasHutchinson’s paper(1981).Heresearchedselfsimilarityoffractalsetsusingsystemoffinitenumberofsimilar contractionmapsofRn.Barnsleycalledafinitesetofcontractionmappsasaniteratedfunction systemsandsystemizedIFStheo… 相似文献