全文获取类型
收费全文 | 105篇 |
免费 | 0篇 |
专业分类
化学 | 60篇 |
物理学 | 45篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2013年 | 2篇 |
2012年 | 3篇 |
2011年 | 7篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 7篇 |
2007年 | 6篇 |
2006年 | 3篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有105条查询结果,搜索用时 31 毫秒
61.
Tanaka YO Ohtsuka S Shindo M Katsumata Y Oyake Y Minami M 《Magnetic resonance imaging》2005,23(8):893-897
OBJECTIVE: Delayed myocardial enhancement is caused by a variety of cardiovascular diseases. The extent of the enhanced area has been examined by the inversion recovery (IR) method, whereby at the inversion time (TI), normal myocardium shows a low signal intensity. In this sequence, as pericardial fat shows a very high intensity, a delayed enhancement just below the pericardium may be indistinct. To improve the accuracy of delayed myocardial enhancement, we employed the spectral presaturation of inversion recovery (SPIR) method. MATERIALS AND METHODS: Thirty-five patients with symptoms of cardiovascular disease aged between 36 and 80 years old (mean age, 62 years old) were investigated. Thirty were men and five were women. Inversion recovery and SPIR images were obtained 25 min after initial administration of a gadolinium-based contrast material. Each TI, when the signal intensity of the normal myocardium was null, was determined by images obtained at serial different TIs. A radiologist and a cardiologist examined each image by a consensus reading. The extent of myocardial enhancement was described as none, subendocardial, transmural and a random pattern in each case. Images were ranked over three levels and were based on whether myocardial enhancement could be easily detected or whether the contour of the myocardium was visualized precisely. Student's t-test was conducted to compare the quality of two sequences in all patients and in 22 patients who showed delayed myocardial enhancement. RESULTS: The imaging quality in evaluating delayed myocardial enhancement in all patients was superior with IR compared with SPIR, although it was not statistically significant. The imaging quality in the patients with delayed myocardial enhancement was similar between SPIR and IR. SPIR was superior to the IR sequence in two of the four patients who exhibited transmural enhancement. CONCLUSION: SPIR exhibited equivalent image quality to IR in evaluating delayed myocardial enhancement. As it has the potential advantage in patients with rich adipose tissue surrounding the myocardium, it can be an alternative sequence to evaluate myocardial viability. 相似文献
62.
63.
64.
65.
Jinqing Qu Toru Fujii Toru Katsumata Yuji Suzuki Masashi Shiotsuki Fumio Sanda Masaharu Satoh Jun Wada Toshio Masuda 《Journal of polymer science. Part A, Polymer chemistry》2007,45(23):5431-5445
2,2,6,6‐Tetramethyl‐1‐piperidinyloxy (TEMPO)‐ and 2,2,5,5‐tetramethyl‐1‐pyrrolidinyloxy (PROXYL)‐containing (R)‐1‐methylpropargyl TEMPO‐4‐carboxylate ( 1 ), (R)‐1‐methylpropargyl PROXYL‐3‐carboxylate ( 2 ), (rac)‐1‐methylpropargyl PROXYL‐3‐carboxylate ( 3 ), (S)‐1‐propargylcarbamoylethyl TEMPO‐4‐carboxylate ( 4 ), and (S)‐1‐propargyloxycarbonylethyl TEMPO‐4‐carboxylate ( 5 ) (TEMPO, PROXYL) were polymerized to afford novel polymers containing the TEMPO and PROXYL radicals at high densities. Monomers 1–3 and 5 provided polymers with moderate number‐average molecular weights of 8200–140,900 in 49–97% yields in the presence of (nbd)Rh+[η6‐C6H5B?(C6H5)3], whereas 4 gave no polymer with this catalyst but gave polymers possessing low Mn (3800–7500) in 56–61% yield with [(nbd)RhCl]2‐Et3N. Poly( 1 ), poly( 2 ), and poly( 4 ) took a helical structure with predominantly one‐handed screw sense in THF and CHCl3 as well as in film state. The helical structure of poly( 1 ) and poly( 2 ) was stable upon heating and addition of MeOH, whereas poly( 4 ) was responsive to heat and solvents. All of the free radical‐containing polymers displayed the reversible charge/discharge processes, whose capacities were in a range of 43.2–112 A h/kg. In particular, the capacities of poly( 2 )–poly( 5 )‐based cells reached about 90–100% of the theoretical values regardless of the secondary structure of the polymer, helix and random. Poly( 1 ), poly( 2 ), and poly( 4 ) taking a helical structure exhibited better capacity tolerance towards the increase of current density than nonhelical poly( 3 ) and poly( 5 ) did. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5431–5445, 2007 相似文献
66.
From an electron spin resonance measurement on a single crystal sample of theS=1 linear chain Heisenberg antiferromagnet Ni(C3H10N2)2NO2ClO4 (NINO) containing a small amount of Cu impurity atoms, we have observed two sets of four hyperfine lines, one of which has almost three times larger field splitting than the other. The hyperfine lines are well explained as arising from the hyperfine interaction between the Cu nuclear spin andthe Cu electron spin which interact with theS=1/2 degrees of freedom induced at the Ni sites by the quantum effect. A large anisotropy in the hyperfine constant is observed andanalyzed using a ligand field theory with covalency effects. 相似文献
67.
Yuuki Takada Masahiro Umehara Ryosuke Katsumata Yoichi Nakao Junji Kimura 《Tetrahedron》2012,68(2):659-669
We successfully completed the total synthesis of kulokekahilide-2, a cytotoxic depsipeptide from the Cephalaspiedean mollusk Phillinopsis speciosa. We have revised the absolute stereochemistry of kulokekahilide-2 to 21-l-Ala, 24-d-MePhe, 37-l-Ile, 43-d-Ala, 15-d-Hica, and 5S,6S,7S-Dtda. We also investigated the cause of the mis-assignment of the configuration in the originally proposed kulokekahilide-2 and concluded that methanolysis using MeONa caused partial racemization, which led to the mis-assignment. The structure–activity relationships of kulokekahilide-2 and its analogs indicate the importance of an l-amino acid at position 21. 相似文献
68.
Katsumata Hideyuki Kawanishi Tomoko Furukawa Mai Tateishi Ikki Kaneco Satoshi 《Journal of Analytical Chemistry》2022,77(5):581-587
Journal of Analytical Chemistry - A sensitive and selective mixed hemimicelles solid phase extraction magnetic material based on sodium dodecyl sulfate-coated magnetite (Fe3O4)/alumina (Al2O3) is... 相似文献
69.
Tetsuya Yamada Norihiro Suzuki Kazuya Nakata Chiaki Terashima Nobuhiro Matsushita Kiyoshi Okada Akira Fujishima Dr. Ken-ichi Katsumata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(11):2380-2385
Solar-driven catalysts on semiconductors to produce hydrogen are considered as a means to solve environmental issues. In this study, H2 production coupling with oxygen consumption by noble metal-free α-FeOOH was demonstrated even though the conduction band edge was lower than the reduction potential of H+ to H2. For activation of α-FeOOH, an electron donor, Hg-Xe irradiation, and low pH (ca. 5) were indispensable factors. The H2 production from H2O was confirmed by GC-MS using isotope-labeled water (D2O) and deuterated methanol. The α-FeOOH synthesized by coprecipitation method showed 25 times more active than TiO2. The photocatalytic activity was stable for over 400 h. Our study suggests that α-FeOOH known as rust can produce H2 by light induction. 相似文献
70.
Ruiping Wang Hiroshi Bando Tetsuhiro Katsumata Yoshiyuki Inaguma Hiroki Taniguchi Mitsuru Itoh 《固体物理学:研究快报》2009,3(5):142-144
We report that the orthorhombic–rhombohedral phase transition temperature in sodium potassium niobate could be tuned from lower to higher than room temperature by incorporating barium zirconate into it. It is revealed that when barium zirconate is between 8 mol% and 15 mol%, the solid solution exhibits rhombohedral symmetry at room temperature. Rietveld analysis shows that the space group of the rhombohedral phase is R3m. It is suggested that a relatively larger B‐cation favors the low‐temperature phase which is a common phenomenon for perovskite ferroelectrics. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献