全文获取类型
收费全文 | 672篇 |
免费 | 13篇 |
国内免费 | 1篇 |
专业分类
化学 | 503篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 30篇 |
物理学 | 148篇 |
出版年
2019年 | 8篇 |
2018年 | 5篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 11篇 |
2013年 | 24篇 |
2012年 | 19篇 |
2011年 | 28篇 |
2010年 | 20篇 |
2009年 | 19篇 |
2008年 | 37篇 |
2007年 | 41篇 |
2006年 | 28篇 |
2005年 | 31篇 |
2004年 | 38篇 |
2003年 | 28篇 |
2002年 | 20篇 |
2001年 | 18篇 |
2000年 | 16篇 |
1999年 | 10篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 11篇 |
1991年 | 12篇 |
1990年 | 13篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 8篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1977年 | 4篇 |
1976年 | 14篇 |
1975年 | 16篇 |
1974年 | 6篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1969年 | 3篇 |
1968年 | 3篇 |
1967年 | 4篇 |
排序方式: 共有686条查询结果,搜索用时 15 毫秒
1.
Shigeyasu Kuroda Mitsunori Oda Shengli Zuo Mayumi Kyogoku Ryuta Miyatake 《Tetrahedron letters》2004,45(43):8119-8122
A new cyclobutene-fused 1,6-methano[10]annulene was synthesized by pyrolysis of the sulfone and sulfinate adducts of 3,4-bis(methylene)-1,6-methano[10]annulene and its physical and chemical properties were disclosed. 相似文献
2.
Mitsuru Ueda Tetsuya Abe Mitsuo Oda 《Journal of polymer science. Part A, Polymer chemistry》1992,30(9):1993-1998
Aromatic poly(thioether ketone)s were prepared by the direct polycondensation of aromatic dicarboxylic acids with aryl compounds containing ether or sulfide structures using phosphorus pentoxide/methanesulfonic acid (PPMA) as a condensing agent and solvent. Polycondensation proceeded smoothly and produced aromatic poly(thioether ketone)s with inherent viscosities up to 0.73 dL/g. The synthesis of substituted aryl ketones by the reaction of substituted benzoic acids with aryl compounds in PMMA was studied in detail to demonstrate the feasibility of the reaction for polymer formation. The thermogravimetry of the aromatic poly(thioether ketone)s showed a 10% weight loss in air and nitrogen at around 450 and 460°C, respectively. © 1992 John Wiley & Sons, Inc. 相似文献
3.
Hidenori Hanaoka Yuka Imamoto Takahiro Hino Tetsuya Kohno Kazunori Yanagi Yoshiaki Oda 《Journal of polymer science. Part A, Polymer chemistry》2007,45(16):3668-3676
Chromium catalysts combined with phosphorous‐bridged bisphenoxy ligands were found to be highly active for ethylene polymerization. The most efficient catalyst precursor among them, generated by combining bis[3‐tert‐butyl‐5‐methyl‐2‐hydroxyphenyl](phenyl)phosphine hydrochloride ( 1a ) and CrCl3(THF)3, was characterized. X‐ray analysis of (3‐tert‐butyl‐5‐methyl‐2‐phenoxy)(3‐tert‐butyl‐5‐methyl‐ 2‐hydroxyphenyl)(phenyl)phosphine bis(tetrahydrofuran)chromium dichloride ( 6 ), obtained by the reaction of 1a and CrCl3(THF)3 in the presence of NaH, revealed a unique structure in which one phenol moiety of the bisphenol did not coordinate to the chromium center. Complex 6 showed higher activities than those observed in the in situ catalyst system. Polyethylene of various molecular weights was obtained with differing activators. The highest activity (113.5 kg mmol (cat)?1 h?1) was observed when TIBA/TB was used as a cocatalyst. A medium molecular weight polymer with narrow molecular weight distribution (Mw = 128,700, Mw/Mn = 1.8) was obtained using a 6 ‐TIBA/B(C6F5)3 system. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3668–3676, 2007 相似文献
4.
5.
Köhler B Enkelmann V Oda M Pieraccini S Spada GP Scherf U 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(14):3000-3004
Novel chiral macrocycles consisting of two rigid oligoarylene rods and two chiral spiroindane clips have been synthesized by condensation of spiroindane diols and CF3-activated alpha-omega-difluorooligoaryls. Since a broad variety of planar aromatic macrocycles is known, our non-planar, chiral rings represent a new class of macrocyclic compounds. The first two examples, which contain quaterphenylene and diphenylbithiophene rods, are presented in this communication; for one of them a crystal structure is given. The chiroptical properties of the macrocycles can be interpreted as an interplay of the "intra-rod" helicity of individual oligoarylene rods and the "inter-rod" helicity between both chromophores of the macrocycle. The macrocycles can act as chiral dopands of commercially available, and novel, polymeric nematic liquid crystals (emissive polyfluorenes). The "intra-rod" helicity of individual oligoarylene rods is the main feature in determining the resulting helical twisting power (HTP). The cholestric induction in mesogenic, emissive polyfluorenes is of special interest for a realization of electronic devices that have a circularly polarized electroluminescence. The results are also important for an understanding of larger ensembles of chiral rodlike molecules, especially their pi-pi interactions. 相似文献
6.
Tulipa gesneriana lectin-erythrocyte (TGL-E) which agglutinates mouse erythrocytes showed a potent mitogenic activity on mouse spleen cells and human peripheral blood lymphocytes, however, TGL-E had only slight mitogenic activity on mouse thymus cells. Its subunit alpha with a molecular weight (MW) of about 26,000 showed a potent mitogenic activity as did that of native lectin, but subunit beta with a MW of about 14,000 showed no activity, indicating that the mitogenic activity of TGL-E originates from subunit alpha. TGL-E stimulated T cell enriched spleen cells which passed through a nylon column, but not spleen cells from a nude mouse or spleen cells treated with anti-Thy 1.2 antibody and complement. Thus, TGL-E stimulates only mouse T cells but not B cells. The other lectin in tulip bulbs, Tulipa gesneriana lectin-yeast showed no mitogenic activity on mouse spleen, thymus cells or human paripheral blood lymphocytes. 相似文献
7.
8.
The titled [3]radialenes are the first, water-soluble hexaaryl[3]radialenes with considerably high electron affinity, their alkali metal reduction giving rise to anion-radicals and dianions stepwise as fairly stable species in degassed tetrahydrofuran. 相似文献
9.
(-)-Pestalotin [(6S, l'S)-6-(1'-hydroxypentyl)-4-methoxy-5,6-d dihydro-2-pyrone 1a]and its three other stereoisomers were synthesized either by utilizing the Sharpless asymmetric epoxidation as the keystep or by derivation from D-(+)-glyceraldehyde acetonide. 相似文献
10.
Katayama H Ishihama Y Oda Y Asakawa N 《Rapid communications in mass spectrometry : RCM》2000,14(14):1167-1178
A novel method for electrophoretic mobility-assisted identifications of proteins, using capillary electrophoresis/mass spectrometry (CE/MS) under methanolic conditions, was developed. The number of functional groups of the enzymatic digest peptides was estimated from a single run CE/MS analysis and utilized as an additional tag for database searching in addition to the mass map of the peptides. The additional amino acid information thus obtained can improve the confidence level of the protein identification. The database searching software algorithm ProFound was modified to accept the tag, based on this new concept. In this study, optimization of the CE/MS conditions for the estimation of basic functional groups was performed as an example. An accurate value of the number of such functional groups was obtained from CE characteristics when methanolic buffer (methanol/formic acid/water = 60:20:20) was used, via an excellent correlation (r = 0.997) between the number of functional groups of the peptides and [MW((2/3))]. The mass spectrometry sensitivity was also improved when using the methanolic buffer in comparison with that obtained using aqueous 1% formic acid buffer. The identification of a protein of Saccharomyces cerevisiae, which was separated by two-dimensional electrophoresis, was performed using the methanolic buffer in combination with sheathless nanoelectrospray CE/MS. A protein spot that had not been identified by MALDI-TOFMS and LC/MS/MS was successfully identified using this new method. 相似文献