全文获取类型
收费全文 | 101篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
化学 | 77篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 17篇 |
物理学 | 5篇 |
出版年
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 1篇 |
2016年 | 9篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 6篇 |
2012年 | 1篇 |
2011年 | 4篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 8篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 3篇 |
1997年 | 2篇 |
1995年 | 7篇 |
1993年 | 2篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1892年 | 1篇 |
1891年 | 1篇 |
1890年 | 2篇 |
排序方式: 共有102条查询结果,搜索用时 15 毫秒
41.
Zhao C Zawisza I Nullmeier M Burchardt M Träuble M Witte I Wittstock G 《Langmuir : the ACS journal of surfaces and colloids》2008,24(14):7605-7613
Patterned cell cultures obtained by microcontact printing have been modified in situ by a microelectrochemical technique. It relies on lifting cell-repellent properties of oligo(ethylene glycol)-terminated self-assembled monolayers (SAMs) by Br2, which is produced locally by an ultramicroelectrode of a scanning electrochemical microscope (SECM). After Br2 treatment the SAM shows increased permeability and terminal hydrophobicity as characterized by SECM approach curves and contact angle measurements, respectively. Polarization-modulation Fourier transform infrared reflection-absorption spectroscopic (PM FTIRRAS) studies on macroscopic samples show that the Br2 treatment removes the oligo(ethelyene glycol) part of the monolayer within a second time scale while the alkyl part of the SAM degrades with a much slower rate. The lateral extension of the modification can be limited because heterogeneous electron transfer from the gold support destroys part of the electrogenerated Br2 once the monolayer is locally damaged in a SECM feedback configuration. This effect has been reproduced and analyzed by exposing SAM-modified samples to Br2 in the galvanic cell Au|SAM|5 microM Br2 + 0.1 M Na2SO4||10 microM KBr + 0.1 M Na2SO4|Au followed by an PM FTIRRAS characterization of the changes in the monolayer system. 相似文献
42.
Zawisza I Bin X Lipkowski J 《Langmuir : the ACS journal of surfaces and colloids》2007,23(9):5180-5194
Combined Langmuir-Blodgett vertical withdrawing and Langmuir-Schaefer horizontal touch (LB-LS) methods were employed to transfer DMPC bilayers onto a Au(111) electrode surface. Charge density measurements and photon polarization modulation infrared reflection absorption spectroscopy were employed to investigate electric field induced changes in the structure of the bilayer. The results show that the physical state and the molecular arrangement found in the monolayer at the air-water interface is to a large extent preserved in the bilayer formed by the LB-LS method. This approach provides an opportunity to produce supported bilayers with a well-designed architecture. The properties of the bilayer formed by the LB-LS method were compared to the properties of the bilayer produced by spontaneous fusion of unilamellar vesicles investigated in an earlier study (Bin, X.; Zawisza, I.; Lipkowski, J. Langmuir 2005, 21, 330-347). The tilt angles of the acyl chains are much smaller in the bilayer formed by the LB-LS method and are closer to the angles observed for vesicles and stacked hydrated bilayers. The tilt angles of the phosphate and choline groups are also smaller and are characteristic of an orientation in which the area per DMPC molecule is small. The electric field induced changes of these angles are also less pronounced in the bilayer formed by the LB-LS method. We have shown that these differences are a result of the higher packing density of the phospholipid molecules in the bilayer formed by the LB-LS method. 相似文献
43.
Jastrzebska I Scaglione JB Dekoster GT Rath NP Covey DF 《The Journal of organic chemistry》2007,72(13):4837-4843
Here we report the stereo- and regiospecific C-6 alkylation of a trans-inden-5-one (from optically pure Hajos-Parrish ketone) with allylic electrophiles. Use of this alkylation procedure has led to an improved synthesis of the benz[f]indene ring system and the first enantiospecific total syntheses of the cyclopenta[b]anthracene and cyclopenta[b]phenanthrene ring systems (two synthetic routes). 相似文献
44.
Two cheap, simple and reproducible methods for the electrophoretic determination of homocysteine thiolactone (HTL) in human urine have been developed and validated. The first method utilizes off-line single drop microextraction (SDME), whereas the second one uses off-line SDME in combination with field amplified sample injection (FASI). The off-line SDME protocol consists of the following steps: urine dilution with 0.2 mol/L, pH 8.2 phosphate buffer (1:2, v/v), chloroform addition, drop formation and extraction of HTL. The pre-concentration of HTL inside a separation capillary was performed by FASI. For sample separation, the 0.1 mol/L pH 4.75 phosphate buffer served as the background electrolyte, and HTL was detected at 240 nm. A standard fused-silica capillary (effective length 55.5 cm, 75 μm id) and a separation voltage of 21 kV (~99 μA) were used. Electrophoretic separation was completed within 7 min, whereas the LOD and LOQ for HTL were 0.04 and 0.1 μmol/L urine, respectively. The calibration curve in urine was linear in the range of 0.1–0.5 μmol/L, with R2 = 0.9991. The relative standard deviation of the points of the calibration curve varied from 2.4% to 14.9%. The intra- and inter-day precision and recovery were 6.4–10.2% (average 6.0% and 6.7%) and 94.9–102.7% (average 99.7% and 99.5%), respectively. The analytical procedure was successfully applied to the analysis of spiked urine samples obtained from apparently healthy volunteers. 相似文献
45.
Jadwiga Walczak Izabella Rychłowska-Himmel 《Journal of Thermal Analysis and Calorimetry》1995,45(5):1015-1019
Phase equilibria up to the solidus line in the system Fe2O3?Fe8V10W16O85 were determined by means of X-ray phase powder diffraction and differential thermal analysis. This system is one of the intersections of the three-component system Fe2O3?V2O5?WO3. The studies revealed that this is not a real binary system, even in the solid state. 相似文献
46.
Jadwiga Walczak Izabella Rychłowska-Himmel 《Journal of Thermal Analysis and Calorimetry》1995,45(5):1021-1026
Phase equlibria in the solid state in the system Fe2WO6?Fe8V10W16O85 were studied by means of X-ray phase powder diffraction and differential thermal analysis, This system is one of the intersections of the three-component system Fe2O3?V2O5?WO3. The investigation demonstrated that the system is not a real two-component system even below the solidus line. 相似文献
47.
The reaction of 4,4′-dihydroxy diphenylsulfide (Ia) and 4,4′-dihydroxydiphenylsulfone (Ib) with hexamethyldisilazane leads to 4,4′-bis)trimethylsiloxy) diphenylsulfide and 4,4′-bis(trimethylsiloxy)diphenylsulfone. Ia and Ib treated with hexamethylcyclotrisilazane form sila-paracyclophanes. 相似文献
48.
The kinetics of NH(b 1Σ+) was studied in the pulsed vacuum UV photolysis of NH3 using the emission at 4707.1 Å from the forbidden transition NH(b 1Σ+ ? X3Σ?). Absolute rate constants were determined for the quenching by NH3 and Ar. 相似文献
49.
50.
Laba Izabella 《偏微分方程通讯》2013,38(5-6):741-762
We prove asymptotic completeness for a system of two particles with opposite charges interacting via a long-range potential decaying faster than |r|-1/2 at infinity in a homogeneous magnetic field. In particular, our result implies asymptotic completeness for the hydrogen atom with finite nuclear mass in a uniform magnetic field, which has not been proven previously. 相似文献