全文获取类型
收费全文 | 368篇 |
免费 | 7篇 |
国内免费 | 3篇 |
专业分类
化学 | 264篇 |
晶体学 | 3篇 |
力学 | 4篇 |
数学 | 1篇 |
物理学 | 70篇 |
无线电 | 36篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 6篇 |
2012年 | 18篇 |
2011年 | 17篇 |
2010年 | 7篇 |
2009年 | 10篇 |
2008年 | 16篇 |
2007年 | 18篇 |
2006年 | 16篇 |
2005年 | 20篇 |
2004年 | 26篇 |
2003年 | 21篇 |
2002年 | 15篇 |
2001年 | 16篇 |
2000年 | 12篇 |
1999年 | 15篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 10篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 2篇 |
1990年 | 7篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1972年 | 1篇 |
1930年 | 1篇 |
排序方式: 共有378条查询结果,搜索用时 31 毫秒
81.
M. Zielinski D. Berg C. Chandlee S. Cihangir T. Ferbel J. Huston T. Jensen F. Lobkowicz T. Ohshima P. Slattery P. Thompson B. Collick S. Heppelmann M. Marshak E. Peterson K. Ruddick A. Jonckheere C. A. Nelson Jr. 《Zeitschrift fur Physik C Particles and Fields》1986,31(4):545-548
Using data on coherent production of π+π+π- systems in π+ collisions with nuclei we exclude the existence ofJ PC=1?+,I=1, exotic hybrid mesons with masses below 1.5 GeV and widths greater than 20 MeV, provided that their primary coupling is to πρ systems. Hybrid states with just such properties have recently been predicted from arguments based on QCD sum rules. Our experimental limit is based on Primakoff production of these states, and on an argument using vector dominance to relate their radiative widths to πρ channels. There has been increasing interest of late in the existence of hybrid states, which, in the case of mesons, contain a valence gluon in addition to aq \(\bar q\) pair in a color-octet state [1–5]. The pursuit of spectroscopic gluon degrees of freedom has been strongly motivated by the general QCD picture of hadrons, as well as by many specific calculations based on QCD sum rules, lattice simulations, and more phenomenological approaches such as QCD-bag models. Although much effort, both thoretical and experimental, has been devoted to the spectroscopy of glueballs, for which several candidates exist [6], it has also been realized that hybrid states may be as amenable to discovery, and perhaps less ambiguous to interpretation. 相似文献
82.
Kimiko Makino Junya Tabata Tatsuya Yoshioka Minoru Fukuda Masahiko Ikekita Hiroyuki Ohshima Hiroshi Terada 《Colloids and surfaces. B, Biointerfaces》2003,29(4):277-284
The purpose of this work is to know the effect of surface properties of liposomes on their phagocytic uptake by macrophages. For this, liposomes were prepared by the Bangham technique from the mixture of phosphatidylcholine (PC) and cholesterol (Chol) incorporated either with phosphatidylserine (PS), phosphatidylethanolamine (PE) or phosphatidic acid (PA). The liposomes thus prepared had diameters in the range between 150 and 260 nm. Electric surface properties of the liposomes and the macrophages differentiated from HL-60RG cells were determined by measuring their electrophoretic mobilities. The phagocytic uptake of liposomes with different contents of PS, PE and PA by macrophage-like HL-60RG cells was investigated by measuring oxygen consumption associated with phagocytic uptake. The phagocytic activity was found to be the highest with the PC–Chol liposomes containing 7 mol% PS, but no significant effects were observed with PA- and PE-containing PC–Chol liposomes. As the uptake was independent of the electric surface property of liposomes, PS was concluded to be specifically important for phagocytic activity of macrophages. 相似文献
83.
Ohshima H 《Journal of colloid and interface science》2002,252(1):119-125
An approximate expression is derived for the electrophoretic mobility of a spherical charged colloidal particle carrying low zeta potential covered with an ion-penetrable uncharged polymer layer in an electrolyte solution. This expression, which becomes Henry's mobility formula in the absence of the polymer layer, is a modification of Henry's mobility formula by taking into account the presence of the uncharged polymer layer. 相似文献
84.
Reaction of diazoindenothiophenes ( 1 and 2 ) with benzoyl acetylene ( 4 ) afforded the rearrangement products ( 6a and b ) of the initial adducts. The major product of the reaction of diazo indenothiophene ( 3 ) with 4 was butadiene derivative 8a . Reaction of 1 with dibenzoylacetylene ( 5a ) gave the rearranged pyrazole ( 12 ), while the reaction of 2 and 3 , afforded the butadiene derivatives ( 8b-d ). 相似文献
85.
Igarashi Y Kumazawa H Ohshima T Satomi H Terabayashi S Takeda S Aburada M Miyamoto K 《Chemical & pharmaceutical bulletin》2005,53(9):1088-1091
We describe the synthesis of 2-[(4-hydroxyphenyl)thio]-7-isopropoxy-5,6-dimethoxy-4H-chromen-4-one 2 from 3,4,5-trimethoxyphenol 6 via the key intermediate, 3-iodo-7-isopropoxy-5,6-dimethoxy-4H-chromen-4-one 3. An important feature of this synthetic scheme involves selective alkylation, which can be achieved by two different routes. One route involves the selective isopropylation of a triacetate derivative 4 under basic conditions. The second route employs the selective demethylation of a trimethoxy derivative 5 under acidic conditions followed by isopropylation. The product of these alternative routes, compound 3, is then converted to a capillarisin sulfur analogue 2 in a one-pot reaction via the imidazolyl intermediate 22. 相似文献
86.
A. L. Jadhav K. P. Naikwadi S. Rokushika H. Hatano M. Ohshima 《Journal of separation science》1987,10(2):77-81
Liquid crystalline polyacrylates (LCPAs) are evaluated as stationary phases for capillary gas chromatography (CGC). Aromatic hydrocarbons as well as polar isomeric compounds are used as test solutes to compare the polarity of the LCPAs with a conventional polysiloxane column and a Carbowax 20M column. The relative polarity of the columns with respect to change in the lateral and terminal substituents is also discussed. Lateral substitution, polarity of the terminal group, together with the solute size, affect the LCPA selectivity. 相似文献
87.
Ohshima T Xu Y Takita R Shimizu S Zhong D Shibasaki M 《Journal of the American Chemical Society》2002,124(49):14546-14547
The enantioselective total synthesis of (-)-strychnine was accomplished through the use of the highly practical catalytic asymmetric Michael reaction (0.1 mol % of (R)-ALB, more than kilogram scale, without chromatography, 91% yield and >99% ee) as well as a tandem cyclization that simultaneously constructed B- and D-rings (>77% yield). Moreover, newly developed reaction conditions for thionium ion cyclization, NaBH3CN reduction of the imine moiety in the presence of Lewis acid to prevent ring opening reaction, and chemoselective reduction of the thioether (desulfurization) in the presence of exocyclic olefin were pivotal to complete the synthesis. The described chemistry paves the way for the synthesis of more advanced Strychnos alkaloids. 相似文献
88.
89.
90.
Ryohei Yonesaki Ibuki Kusagawa Hiroyuki Morimoto Tamio Hayashi Takashi Ohshima 《化学:亚洲杂志》2020,15(4):499-502
Enantioselective addition of boronic acids to N‐unsubstituted isatin‐derived ketimines was realized using rhodium(I)/chiral diene catalysts. The reactions can be performed in the presence of catalytic amounts of a base to give adducts in high yield with high enantioselectivity. Preliminary mechanistic information including a computational model to explain the observed enantioselectivity is also provided. 相似文献