全文获取类型
收费全文 | 80篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
化学 | 41篇 |
晶体学 | 2篇 |
数学 | 8篇 |
物理学 | 30篇 |
出版年
2023年 | 1篇 |
2021年 | 1篇 |
2018年 | 1篇 |
2012年 | 1篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 5篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1955年 | 2篇 |
1939年 | 3篇 |
1937年 | 1篇 |
排序方式: 共有81条查询结果,搜索用时 265 毫秒
1.
Ahmed Waqar Chowdhury Z. Z. Kazi S. N. Johan MR. Akram Naveed Oon C. S. Abdelrazek Ali H. 《Journal of Thermal Analysis and Calorimetry》2021,144(4):1517-1534
Journal of Thermal Analysis and Calorimetry - In recent decades, the growth of heat transfer using nanomaterials in the conventional base fluid has caught the attention of researchers... 相似文献
2.
In quasi-steady operation, convection currents in a Bridgmandevice, used for producing a semi-conductor crystal, createinhomogeneities that may make the crystal unusable. It has oftenbeen suggested that additional forces due to rotation or magnetismmight be efficacious in reducing the segregation of the elementsof the alloy. It has been found that, over a wide range of rotationrates, there is no improvement in performance due to rotationabout the vertical axis. However, numerical results that havebeen obtained previously (Lee & Pearlstein, J. Crys. Growth240, 2002) indicate that, when effects of centrifugal buoyancyare introduced, a substantial reduction in segregation is achieved.In the work reported here, by contrast, in which we extend previouslarge-Rayleigh-number asymptotic analysis to include centrifugalbuoyancy, we find no improvement in radial segregation, butrather increasing segregation with increasing rotation rate. 相似文献
3.
Ruth Freitag Thomas Baltes Martin Eggert 《Journal of polymer science. Part A, Polymer chemistry》1994,32(16):3019-3030
Several batches of poly-N,N-diethylacrylamide were synthesized by anionic and by group transfer polymerization (GTP). A radical poly-N,N-diethylacrylamide prepared from the same monomer was also included in the comparison. According to matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) both types of living polymerization resulted in narrow molecular weight distributions with Mw/Mn values below 1.5. Average molecular weights (Mn) between 888 and 4678 g/mol were calculated in these cases. The radical polymer had an average molecular weight (Mn) of approximately 130,000 g/mol. The dry anionic and GTP polymers were investigated by differential scanning calorimetry (DSC) and x-ray diffraction spectrometry. Evidence for partial crystallinity in the solid state was found. The conformation of all polymers was examined by high resolution (600 MHz) NMR. According to these measurements, 75% of the ? CHR? groups of the anionic poly-N,N-diethylacrylamide were located in an isotactic triade. The remaining 25% had heterotactic structure, while no indication for the presence of syndiotactic protons was found. Poly-N,N-diethylacrylamide prepared by GTP, on the other hand, had mainly syndiotactic structure. The aqueous solutions of the polymers showed phase separation upon heating. Whereas the lower critical solution temperature (LCST) was approximately 30°C in the case of the poly-N,N-diethylacrylamide prepared by GTP and by radical polymerization, uncommonly high LCSTs of more than 40°C were observed for the anionic poly-N,N-diethylacrylamide. © 1994 John Wiley & Sons, Inc. 相似文献
4.
Classical inhibitors of human cytochrome P450 3A4 activity, such as ketoconazol and quercetin, are tested to prove the efficiency of a new metabolisation model using living entire cells. Grapefruit juice is a well-known potent inhibitor of cytochrome P450 3A4 activity. With regard to the clinical relevance of grapefruit juice-drug interactions, an investigation of other common juices is undertaken with this in vitro model. The CYP3A4 activity is measured by the formation of the 6beta-hydroxytestosterone, which is quantified by an isocratic high performance liquid chromatography. It is demonstrated for the first time that lemon juice significantly inhibits by 60+/-3% the CYP3A4-mediated oxidation. Grapefruit juice inhibits this activity by 82+/-4%. The mechanism of lemon juice inhibition is competitive, whereas it is mixed for grapefruit juice. These results suggest that our in vitro model combined with our analytical method is applicable for the investigation of the inhibition of CYP3A4 not only by chemical inhibitors but also by natural food products. 相似文献
5.
Werner Baltes 《Nachrichten aus der Chemie》1981,29(6):361-361
6.
7.
8.
Fischer RF Baltes C Weiss K Pazhenkottil A Rudin M Boesiger P Kozerke S 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,211(1):80-88
In this work Linear Response Equilibrium (LRE) and Echo-planar spectroscopic imaging (EPSI) are compared in terms of sensitivity per unit time and power deposition. In addition an extended dual repetition time scheme to generate broad stopbands for improved inherent water suppression in LRE is presented. The feasibility of LRE and EPSI for assessing cholesterol esters in human carotid plaques with high spatial resolution of 1.95×1.15×1.15 mm(3) on a clinical 3T MR system is demonstrated. In simulations and phantom experiments it is shown that LRE has comparable but lower sensitivity per unit time relative to EPSI despite stronger signal generated. This relates to the lower sampling efficiency in LRE relative to EPSI as a result of limited gradient performance on clinical MR systems. At the same time, power deposition of LRE is significantly reduced compared to EPSI making it an interesting niche application for in vivo high field spectroscopic imaging of metabolites within a limited bandwidth. 相似文献
9.
S.D. Gopal Ram G. Ravi MR. Manikandan T. Mahalingam M. Anbu Kulandainathan 《Superlattices and Microstructures》2011,50(4):296-302
In the present work, a controlled growth of ZnO nanostructures by manipulating Zn metal ion concentration by the chelating action of ethylene diaminetetra acetic acid in hydrothermal method is studied. EDTA produces metal–chelate complex by the formation of bidentate ligand with Zn2+ in the solution and diminishes the reactivity of Zn metal cations. Concentration of EDTA in the mother solution was varied in different ranges like 3, 5 and 10 mM while retaining the zinc metal salt and the NaOH concentration the same. Three different morphologies of wurtzite structured ZnO nanostructures such as nanorods-bunch, separate/discrete uniformly sized hexagonal nanorods and tapered flower petals like shapes are achieved by 3, 5 and 10 mM strengths of EDTA, respectively. The medium concentration 5 mM of EDTA is found to have moderate control over producing ZnO nanostructures of uniform diameter and a high aspect (length to diameter) ratio. An array of vertically aligned free standing ZnO nanorods with uniform spacing is successfully achieved by the addition of 5 mM of EDTA in the mother solution and the same is studied for its fluorescence property at an excitation of 325 nm and it has exhibited a characteristic UV emission of ZnO around 383 nm. 相似文献
10.