全文获取类型
收费全文 | 217篇 |
免费 | 16篇 |
国内免费 | 2篇 |
专业分类
化学 | 142篇 |
晶体学 | 7篇 |
力学 | 4篇 |
数学 | 27篇 |
物理学 | 55篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 14篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 13篇 |
2015年 | 12篇 |
2014年 | 8篇 |
2013年 | 22篇 |
2012年 | 11篇 |
2011年 | 21篇 |
2010年 | 10篇 |
2009年 | 12篇 |
2008年 | 12篇 |
2007年 | 14篇 |
2006年 | 11篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1980年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有235条查询结果,搜索用时 15 毫秒
201.
S. Acar A. Ylldlz M. Kasap M. Bosi 《中国物理快报》2007,24(8):2373-2375
Hall effect measurements in undoped In0.5Ga0.5 P/GaAs allo grown by metal organic vapour-phase epitaxy (MOVPE) have been carried out in the temperat.ure range 15-350K. The experimenta.1 results are analysed using a two-band model including conduction band transport calculated using an iterative solution of the Boltz- mann equation. A good agreement was obtained between theory and experiment. The impurity contents of In0.5Ga0.5 P/GaAs alloy, such as donor density ND, acceptor density NA and donor activation energy εD, were also determined. 相似文献
202.
203.
A Bifunctional Photosensitizer for Enhanced Fractional Photodynamic Therapy: Singlet Oxygen Generation in the Presence and Absence of Light 下载免费PDF全文
Dr. Ilke Simsek Turan Deniz Yildiz Abdurrahman Turksoy Dr. Gurcan Gunaydin Prof. Dr. Engin U. Akkaya 《Angewandte Chemie (International ed. in English)》2016,55(8):2875-2878
The photosensitized generation of singlet oxygen within tumor tissues during photodynamic therapy (PDT) is self‐limiting, as the already low oxygen concentrations within tumors is further diminished during the process. In certain applications, to minimize photoinduced hypoxia the light is introduced intermittently (fractional PDT) to allow time for the replenishment of cellular oxygen. This condition extends the time required for effective therapy. Herein, we demonstrated that a photosensitizer with an additional 2‐pyridone module for trapping singlet oxygen would be useful in fractional PDT. Thus, in the light cycle, the endoperoxide of 2‐pyridone is generated along with singlet oxygen. In the dark cycle, the endoperoxide undergoes thermal cycloreversion to produce singlet oxygen, regenerating the 2‐pyridone module. As a result, the photodynamic process can continue in the dark as well as in the light cycles. Cell‐culture studies validated this working principle in vitro. 相似文献
204.
Dr. Avijit Maiti Benedict J. Elvers Dr. Sachinath Bera Felix Lindl Dr. Ivo Krummenacher Prof. Prasanta Ghosh Prof. Dr. Holger Braunschweig Prof. Cem B. Yildiz Prof. Dr. Carola Schulzke Dr. Anukul Jana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(28):e202104567
Herein, we disclose cyclic(alkyl)(amino)carbenes (CAACs) to be one-electron reductants under the formation of a transient radical cation as indicated by EPR spectroscopy. The disclosed CAAC reducing reactivity was used to synthesize acyclic(amino)(aryl)carbene-based Thiele and Chichibabin hydrocarbons, a new class of Kekulé diradicaloids. The results demonstrate CAACs to be potent organic reductants. Notably, the acyclic(amino)(aryl)carbene-based Chichibabin's hydrocarbon shows an appreciable population of the triplet state at room temperature, as evidenced by both variable-temperature NMR and EPR spectroscopy. 相似文献
205.
Tülay Yilmaz Hande Gülü
zdemir
zarslan Emel Yildiz Abdülkadir Kuyulu Ekrem Ekinci Attila Güngr 《Journal of polymer science. Part A, Polymer chemistry》1997,35(14):2981-2990
In this work, thermal solution imidization kinetics of two high performance polyimides, prepared from the polycondensation of pyromellitic dianhydride (PMDA) and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) with 4,4′-bis(3-aminophenoxy)diphenylsulfone (DAPDS) were investigated using nonaqueous titration technique with tetramethylammonium hydroxide. Most of the kinetic investigations, found in the literature, are based on the aromatic p-diamines.1,2 In the present work, attention was focused on imidization kinetics with m-substituted aromatic diamines having electron donating ( O ) and electron withdrawing ( SO2 ) groups in the same molecule. Kinetic parameters, namely the rate constants, activation energies, entropies and enthalpies of imidization reactions were determined and compared with the literature values. It is reported in literature3 that electron affinities of dianhydrides and ionization potentials of diamines, have strong influence on the reaction rate and activation energies of imidization. Activation energy (Ea) values were found to be 66 and 57 kJ/mol for DAPDS/PMDA and DAPDS/BTDA respectively, and order of reaction was found to be second order. Polyimides DAPDS/PMDA and DAPDS/BTDA, subjected to kinetic investigation, showed glass transition temperatures of 267°C and 241°C, both were found to be thermally stable up to 500°C. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2981–2990, 1997 相似文献
206.
D. P. Belozorov V. N. Derkach S. V. Nedukh A. G. Ravlik S. T. Roschenko I. G. Shipkova S. I. Tarapov F. Yildiz 《International Journal of Infrared and Millimeter Waves》2001,22(11):1669-1682
The paper is devoted to the investigation of high frequency magnetic features of multilayered metallic structures (Co/Cu) demonstrating the Giant Magnetic Resistance effect (GMR-effect) and Giant Magnetic Impedance effect (GMI-effect). Dynamic features have been investigated in dependence on the distance between magnetic Co-layers and analyzed in comparison with static magnetic features. Ferromagnetic resonance response as well as non-resonance magnetoimpedance at small applied static magnetic field have been studied. Experiments were carried out at room temperatures in frequency band 20-37GHz for the ferromagnetic resonance technique and in frequency band 30-140GHz for study the low field non-resonance magnetoimpedance effects. 相似文献
207.
The fermionic oscillator defined by the algebraic relations cc
*
+c
*
c = 1 and c
2
= 0 admits the homogeneous group O(2) as its invariance group. We show that the structure of the inhomogeneus invariance group of this oscillator is a quantum
group.
Received: 15 July 2002 / Revised version: 14 October 2002 / Published online: 19 February 2003 相似文献
208.
The magnetization of Gd diffused YBa2Cu3O7-x is measured by a vibrating sample magnetometer (VSM) at selected temperatures (5, 25, 50, 77 K). The experimental results for the magnetization are analyzed in the critical state framework involving Kim-Anderson field dependence Jc(H)=Jc0/(1+|H|/H0)n of critical current density and equilibrium magnetization M eq . It is found that the inclusion of the equilibrium magnetization becomes more important at higher temperatures. At 77 K, the shape of the isothermal M-H hysteresis curve is governed by the equilibrium magnetization. Some superconducting parameters are determined by fitting the calculated curves to the experimental data. 相似文献
209.
Emre Cevik Alaaddin Cerit Huseyin Tombuloglu Hussein Sabit Huseyin Bekir Yildiz 《Analytical letters》2019,52(7):1138-1152
The fabrication of amperometric biosensors based on whole cell Gluconobacter oxydans DSMZ 2343 (G. oxydans) and glucose oxidase (GOx) was performed for the detection of glucose. Glassy carbon electrodes (GCE) were coated with a 10-(4H-dithiyeno [3,2-b:2’,3’-d]pyroll-4-il)decan-1-amine (DTP-alkyl-NH2) polymer using an electropolymerization method and the formed interface was used to connect the bacteria and the enzyme to the electrode. The transfer of electrons from enzyme to electrode was successfully demonstrated by the biocatalytic activity and unique morphology of the conducting polymer. Characterization of the biosensors was assessed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) analyses. The detection limits of the enzyme and microbial based biosensors for glucose were 0.022 and 0.081?mM, respectively. The broad linear dynamic ranges of the GOx and G. oxydans biosensors were observed to be 0.045–50.0 and 0.19–50.0?mM, respectively. The analytical performances of biosensors were compared according to the following figures of merit: detection limits, limits of quantification, pH and current response time. In addition, to demonstrate the applicability of the biosensors, real-time measurements and recovery studies were evaluated. 相似文献
210.