全文获取类型
收费全文 | 130篇 |
免费 | 3篇 |
专业分类
化学 | 94篇 |
力学 | 4篇 |
数学 | 2篇 |
物理学 | 33篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 1篇 |
2020年 | 7篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 6篇 |
2012年 | 9篇 |
2011年 | 8篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 9篇 |
2007年 | 10篇 |
2006年 | 2篇 |
2005年 | 6篇 |
2004年 | 3篇 |
2003年 | 12篇 |
2002年 | 2篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 1篇 |
排序方式: 共有133条查询结果,搜索用时 0 毫秒
101.
Naofumi Naga Hitomi Nagino Midori Iwashita Tomoharu Miyanaga Hidemitsu Furukawa 《Journal of polymer science. Part A, Polymer chemistry》2015,53(11):1360-1368
Organic–inorganic hybrid gels containing Si‐vinylene units have been synthesized by a hydrosilylation reaction of tri‐ or tetra‐ethynyl aryl compounds, 1,3,5‐triethynylbenzene (TEB), 3,3′,5,5′‐tetraethynylbiphenyl (TEBP), or tetrakis(4‐ethynylphenyl)methane (TEPM), and bisdimethylsilyl compounds, 1,1,3,3‐tetramethyldisiloxane (TMDS) or 1,4‐bisdimetylsilylbenzene (BDMSB), in toluene. Network structure of the resulting gels was quantitatively characterized by a scanning microscopic light scattering. The reactions yielded the gels having homogeneous network structure of 1.5–2.9 nm mesh size under the monomer concentrations that were relatively higher than the critical gelation concentration. The gels obtained from TEB showed broad absorption in the range from 340 to 370 nm, and emission in the range from 440 to 490 nm. The TEB–BDMSB gels showed remarkable red shift of the emission in comparison with that of the corresponding reaction solutions derived from the network formed by σ–π conjugation. The TEPM–TMDS, BDMSB gels exited by 280 nm showed not only the emission peak at around 360 nm derived from TEPM, but the broad peak at around 420 nm, which should be derived from interaction between phenyl groups of TEPM in the gels. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1360–1368 相似文献
102.
Dr. Aiichiro Nagaki Yuya Moriwaki Suguru Haraki Akira Kenmoku Naofumi Takabayashi Atsushi Hayashi Prof. Dr. Jun-Ichi Yoshida 《化学:亚洲杂志》2012,7(5):1061-1068
The use of Pd catalysts that contained a carbene ligand, such as PEPPSI-SIPr, speeded up the Murahashi coupling of ArLi with ArBr, by enabling its integration with the Br/Li exchange of ArBr with BuLi in flow. Space integration realized the rapid cross-coupling of two different ArBr substrates. However, the cross-coupling reaction with vinyl halides could not be achieved under similar conditions. Pd(OAc)2 was an effective catalyst, and the space integration of the Br/Li exchange of ArBr with BuLi and the Murahashi coupling with vinyl halides was successfully achieved. 相似文献
103.
Takeshi Yagi Naofumi Kuboki Yoshihisa Suzuki Naotaka Uchino Kazunori Nakamura Kazuaki Yoshida 《Optical Review》1997,4(5):596-600
A new fiber-optic ammonia sensor utilizing rectangular-cladding eccentric-core fiber and a sensitive film containing an indicator dye is demonstrated. The sensitive film is a SiO2-GeO2 gel film including an indicator dye of bromocresol purple or bromocresol green, which is dip-coated by a sol-gel technique. The attenuation of this sensor changes depending on the concentration of ammonia at the wavelength range of 500–700 nm. This sensor can detect several ppm of gaseous ammonia. Various factors determining the sensitivity to detect the ammonia gas and time response of the sensor are also studied. 相似文献
104.
Masahiro Tanabe Katsuyoshi Ito Ayame Shimizu Takeshi Fujita Hideko Onoda Shigenari Yamatogi Yasuo Washida Naofumi Matsunaga 《Magnetic resonance imaging》2009
Purpose
The aim of this study was to determine the adequate MR sequence for the lesion conspicuity of hepatocellular lesions with increased iron uptake on superparamagnetic iron oxide (SPIO)-enhanced MRI.Materials and Methods
SPIO-enhanced MRI was performed using a 1.5-T system. Among 25 patients with hypovascular hepatocellular nodules on contrast-enhanced dynamic CT (no early enhancement at arterial phase and hypoattenuation at equilibrium phase), 39 lesions with increased iron uptake on SPIO-enhanced MRI were evaluated. SPIO-enhanced MRI included (1) T1-weighted in-phase gradient recalled echo (GRE) images, (2) T2-weighted fast spin echo (FSE) images, (3) T2*-weighted GRE with moderate TE (7 ms) and (4) long TE (12 ms). The lesion-to-liver contrast-to-noise ratios of the hepatocellular nodule and the signal-to-noise ratio (SNR) of the hepatic parenchyma were calculated by one radiologist for a quantitative assessment. MR images were reviewed retrospectively by two independent radiologists to compare the subjective lesion conspicuity in each image set based on a four-point rating scale.Result
The mean lesion-to-liver contrast-to-noise ratios with T2*-weighted GRE with moderate TE (7 ms) was highest (5.79±3.71) and was significantly higher than those with T1-weighted, in-phase images (3.79±3.23, P<.01), T2-weighted images (2.72±1.52, P<.001) and T2*-weighted GRE with long TE (12 ms) (3.93±2.69, P<.05). The subjective rating of lesion conspicuity was best on the T2*-weighted GRE with moderate TE (7 ms), followed by that on the T2*-weighted GRE with moderate TE (7 ms; P<.05).Conclusion
T2*-weighted GRE sequence with moderate TE (7 ms) showed high lesion-to-liver contrast-to-noise ratios in hepatocellular lesions with increased iron uptake on SPIO-enhanced MRI, indicating better lesion conspicuity of hypointense hepatocellular nodules in cirrhosis or chronic hepatitis. 相似文献105.
Ikuo?KonishiEmail author Yasnobu?Ito Naofumi?Sakauchi Manami?Kobayashi Yoshio?Tsunazawa 《Optical Review》2003,10(6):592-595
A new four-wavelength optical imager has been developed for the evaluation of various vascular diseases. Four-wavelength optical intensity images are transformed to an oxygenation mapping, which further provide maps of rapid changes in hemoglobin distribution in human skin related with peripheral blood flow. This paper presents the configuration of the system and test measurements for foot disease. Forty-nine volunteers took part in our measurements with an occlusion test of their legs. Some differences were observed in oxygenation change between healthy volunteers and patients, and arteriosclerosis obliterate (ASO) patients and healthy volunteers were clearly distinguishable. 相似文献
106.
Various allylic alcohols reacted with n-butyl acrylate in the presence of p-toluenesulfonic anhydride and palladium catalysts to yield the corresponding n-butyl 2,5-dienoates with high regioselectivity. 相似文献
107.
Hayashida M Ito K Fujita T Shimizu A Sasaki K Tanabe M Matsunaga N 《Magnetic resonance imaging》2008,26(1):65-71
PURPOSE: The purpose of this study was to evaluate differences in the degrees of contrast enhancement effects of small hepatocellular carcinomas (HCCs) in patients with cirrhosis between helical computed tomography (CT) and magnetic resonance (MR) imaging during multiphasic contrast-enhanced dynamic imaging and to determine the diagnostic value of MR imaging especially in assessing hypovascular HCCs detected as hypoattenuating nodules on late-phase CT. SUBJECTS AND METHODS: This study included 64 small HCCs (<3 cm in diameter) in 40 patients with chronic hepatitis or cirrhosis who underwent multiphasic (arterial, portal and late phases) contrast-enhanced dynamic helical CT and MR imaging. The contrast enhancement patterns of each lesion in the arterial and late phases were evaluated by two radiologists experienced in liver MR imaging and categorized as one of five grades (1=hypoattenuated/hypointense; 2=slightly hypoattenuated/hypointense; 3=isoattenuated/isointense; 4=slightly hyperattenuated/hyperintense; 5=hyperattenuated/hyperintense), compared with the surrounding liver parenchyma. RESULT: Forty-three (67%) of 64 lesions showed Grade 4 (n=24) or Grade 5 (n=19) enhancement on arterial-phase CT, while 51 (80%) of 64 lesions showed Grade 4 (n=20) or Grade 5 (n=31) enhancement on arterial-phase MR imaging, indicating hypervascular HCCs. The grading score of hypervascular HCCs on arterial-phase MR imaging (mean: 4.61) was significantly (P<.01) higher than that for hypervascular HCCs on arterial-phase CT (mean: 4.20), showing better detection of the hypervascularity (arterial enhancement) of the lesion on arterial-phase MR imaging. Regarding hypovascular HCCs, all (100%) of 21 hypovascular HCCs on CT showed Grade 1 (n=10) or Grade 2 (n=11) enhancement on late-phase CT, seen as hypoattenuation. In contrast, 8 (62%) of 13 hypovascular HCCs on MR imaging showed Grade 1 (n=1) or Grade 2 (n=7) enhancement on late-phase MR imaging, seen as hypointensity. Grading scores of hypovascular HCCs on late-phase images were significantly (P<.001) lower on CT than on MR imaging (mean score: 1.52 vs. 2.31), indicating better washout effects for hypovascular HCCs on late-phase CT. CONCLUSION: The washout effects for small HCCs on late-phase MR imaging were inferior to those for small HCCs on late-phase CT. Especially, hypovascular HCCs demonstrated as hypoattenuating nodules on late-phase CT were often not seen on late-phase MR imaging, requiring careful evaluation of other sequences, including unenhanced T(1)-weighted and T(2)-weighted MR images. 相似文献
108.
Naofumi Naga Ayaka Okada Yuka Satoh Hidemitsu Furukawa Takahiro Yamamoto 《Liquid crystals》2016,43(11):1616-1625
Organic–inorganic hybrid liquid crystal (LC) gels have been synthesised by the thiol-ene reaction of a multifunctional cyclic siloxane, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane (TVMCTS) and alkane dithiols, 1,6-hexanedithiol (HDT) or 1,9-decanedithiol (DDT), in LC matrices, 4-cyano-4?-pentylbiphenyl (5CB) or 4′-n-octyl-4-cyano-biphenyl (8CB). The LC gels were prepared in an isotropic phase at 70°C or mesophases at 25°C using radical initiators. The phase transition temperatures from a mesophase to an isotropic phase of the resulting gels were lower than those of the original LCs. The gels containing 8CB (8CB gels) prepared at 25°C showed two phase transitions: smectic-to-nematic and nematic-to-isotropic transitions. By contrast, the 8CB gels synthesised in the isotropic phase showed only one phase transition from smectic phase directly to isotropic phase. Reaction conversions in the LC gels prepared at 70°C were higher than that in the gels prepared at 25°C. Scanning microscopic light scattering analysis of the LC gels cleared homogeneous small size mesh with a small amount of large defect. Polarisation micrographs of the LC gels showed framed optical textures derived from the LC molecules at room temperature. The LC gels containing more than 90 wt% of LC showed electro-optic response. 相似文献
109.
110.