全文获取类型
收费全文 | 615篇 |
免费 | 15篇 |
国内免费 | 4篇 |
专业分类
化学 | 481篇 |
晶体学 | 5篇 |
力学 | 6篇 |
数学 | 14篇 |
物理学 | 128篇 |
出版年
2020年 | 8篇 |
2019年 | 15篇 |
2018年 | 8篇 |
2017年 | 5篇 |
2016年 | 10篇 |
2015年 | 21篇 |
2014年 | 11篇 |
2013年 | 23篇 |
2012年 | 23篇 |
2011年 | 35篇 |
2010年 | 21篇 |
2009年 | 16篇 |
2008年 | 30篇 |
2007年 | 33篇 |
2006年 | 42篇 |
2005年 | 44篇 |
2004年 | 32篇 |
2003年 | 31篇 |
2002年 | 25篇 |
2001年 | 16篇 |
2000年 | 19篇 |
1999年 | 8篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1993年 | 13篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 11篇 |
1988年 | 2篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 2篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1972年 | 5篇 |
1970年 | 2篇 |
1937年 | 1篇 |
排序方式: 共有634条查询结果,搜索用时 15 毫秒
81.
82.
Production, isolation, and characterization of group-2 metal-containing endohedral metallofullerenes
T. John S. Dennis H. Shinohara 《Applied Physics A: Materials Science & Processing》1998,66(3):243-247
80 , Ca/Sr/Ba@C82, Ca/Sr/Ba@C84) are investigated for the first time by UV-Vis-NIR absorption spectroscopy and high-resolution 13C NMR. Direct evidence of the endohedral nature and cage structures are revealed by these measurements. Furthermore, we have
found that each metallofullerene has 2–4 structural isomers, which have been isolated by multistage high-performance liquid
chromatography. These isomers have different cage structures and give characteristic UV-Vis-NIR absorption spectra.
Received: 22 September 1997/Accepted: 16 October 1997 相似文献
83.
84.
A novel synergistic extraction system was investigated for the possible selective separation of light lanthanoids using an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, as an extraction solvent and 2-thenoyltrifluoroacetone and 18-crown-6 as extractants. Trivalent lanthanum was efficiently extracted as a cationic ternary complex by the cation-exchange process, whereas europium and lutetium showed relatively low extractability without forming respective ternary complexes. This result is thought to originate in a size-fitting effect of 18-crown-6 to lanthanum and the unique nature of the ionic liquid as a chelate extraction solvent. 相似文献
85.
86.
Setsuji Tone Kouichi Shinohara Yasuo Igarashi Tsutao Otake 《Journal of membrane science》1984,19(2):195-208
Investigations were made of the water flux rate and rejection characteristics of aromatic substances in aqueous solutions using a thin, dense cellulose acetate membrane in reverse osmosis experiments. The aromatic substances used were phenol, aniline, hydroquinone and p-chlorophenol. The permeate became more enriched in aromatic compounds as compared to the feed solution as the water content of the membrane increased. By considering both the effects of pressure on the chemical potential of a component and the contribution of viscous flow to the overall transport of that component in the hydrated membrane, a theoretical relationship was developed to predict the negative solute rejection of the membrane. Based on this proposed theory, the permeability coefficients of water and organic solute were estimated from experimental solute rejection data, including negative values. The permeability coefficients of components were in good agreement with previously established correlations in measurements of partition and diffusion coefficients. 相似文献
87.
A method for the quantitative estimation of methyltestosterone and methyltestosterone-d3 in biological fluids has been developed using gas chromatography-mass spectrometry-selected-ion monitoring. Methyltestosterone-d6 was used as an internal standard. Methyltestosterone and methyltestosterone-d3 in serum were determined based on the peak height ratios of the molecular ions of methyltestosterone, methyltestosterone-d3 and methyltestosterone-d6. Sensitivity, specificity, precision, accuracy and reproducibility of the present method were demonstrated to be satisfactory for application to pharmacokinetic and bioavailability studies. 相似文献
88.
Masahiro Kawasaki Kazuo Kasatani Hiroyasu Sato Hisanori Shinohara Nobuyuki Nishi 《Chemical physics》1984,88(1):135-142
Molecular beams of halogenated hydrocarbons containing chlorine and bromine atoms were photodissociated using an excimer laser at 193 nm. Molecules photodissociated were HCCBr, HCCCH2Br, HCCCH2Cl, CH3Cl, C2H5Cl and i-C3H7Cl. The time-of-flight distributions of the photofragments were measured in order to study the primary processes and the dissociation dynamics. Generalizations consistent with the data are that atomic products (RX → R + X) result from direct dissociation of the CX repulsive singlet state, molecular elimination (RX → R′ + HX) is a result of a crossover to the ground state and triplet states are involved in the photodissociation of alkyne compounds. 相似文献
89.
Niikura K Kamitani R Kurogochi M Uematsu R Shinohara Y Nakagawa H Deguchi K Monde K Kondo H Nishimura S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(13):3825-3834
We have developed an effective and practical trap-and-release method based on chemoselective ligation of carbohydrates with reactive aminooxyl groups attached to the surface of nanoparticles (referred to as glycoblotting nanoparticles). These glycoblotting nanoparticles were synthesized by UV irradiation of diacetylene-functionalized lipids that contain the aminooxyl group. The glycoblotting nanoparticles captured carbohydrates in aqueous solution under mild conditions and were collected by simple centrifugation. The trapped carbohydrates were effectively released from the nanoparticles under acidic conditions to give pure oligosaccharides. This glycoblotting process reduced the time required for the purification process of carbohydrates to less than 6 h, compared to the several days needed for conventional chromatographic techniques. The oligosaccharides (N-glycan) were released from ovalbumin (glycoprotein) by PNGase F after tryptic digestion. MALDI-TOF mass spectra before purification did not show any significant signals corresponding to N-glycans because these signals were hidden by the large signals of the abundant peptides. However, after purification with the glycoblotting nanoparticles, only signals corresponding to oligosaccharides appeared. We also demonstrated a clear analysis of the oligosaccharides contained in the mice dermis by means of glycoblotting. 相似文献
90.