全文获取类型
收费全文 | 84篇 |
免费 | 0篇 |
专业分类
化学 | 59篇 |
数学 | 1篇 |
物理学 | 24篇 |
出版年
2023年 | 1篇 |
2018年 | 1篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 5篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 3篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有84条查询结果,搜索用时 15 毫秒
31.
Chen CC Park H den Nijs M 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,60(3):2496-2500
The width W of the active region around an active moving wall in a directed percolation process diverges at the percolation threshold p(c) as W approximately Aepsilon(-nu( parallel)) ln(epsilon(0)/epsilon), with epsilon=p(c)-p, epsilon(0) a constant, and nu( parallel)=1.734 the critical exponent of the characteristic time needed to reach the stationary state xi( parallel) approximately epsilon(-nu(parallel)). The logarithmic factor arises from screening the statistically independent needle shaped subclusters in the active region. Numerical data confirm this scaling behavior. 相似文献
32.
Jeanne Brygier Michel Gelbcke Claude Guermant Michelle Nijs Danielle Baeyens-Volant Yvan Looze 《Applied biochemistry and biotechnology》1993,42(2-3):127-135
Carbonylimidazol-l-yl-mPEG is obtained quantitatively by reacting methoxypoly(ethyleneglycol) (mPEG) with 1.1 Eq of N,N′-carbonyldiimidazole
in the presence of a stoechiometric amount of 4-dimethyl-aminopyridine used as hypernucleophilic acylation catalyst. Carbonylimidazol-l-yl-mPEG is quite stable in aqueous solutions with half-lives up to 70 h in pHs ranging from 6.0 to 7.0 at 25‡C. From reactivity
studies toward amines with various nucleophilic strengths, it is suggested that carbonylimidazol-l-yl-mPEG may be best used to modify α-amino terminal function of proteins selectively or to introduce amino function on PEG chains. 相似文献
33.
A new analogue of the antitumor pericosines possessing a bicyclo[2.2.2]octene skeleton has been synthesized from methyl gallate using oxidative dearomatization and regio- and diastereoselective Diels-Alder reaction as the key steps. 相似文献
34.
Addition of the Allenic amine H2C═C═CHNMe2 and the corresponding N-morpholinoallene to a solution of an aromatic or heteroaromatic aldehyde, RCH═O, and lithium bromide in tetrahydrofuran followed by treatment of the reaction mixture with a small amount of acetic acid at elevated temperatures affords the aldehydes RCH═C(CH2NR'2)CH═O (NR'2=NMe2 or morpholino) in reasonable yields. 相似文献
35.
36.
Mohamed Azarkan Michelle Nijs Nicole Smolders Jlaude Guermant Jean Vlncentelli Yvan Looze 《Applied biochemistry and biotechnology》1996,60(2):167-183
The four cysteine proteinases, papain, chymopapain, caricain, and endoproteinase Gly-C were isolated and purified as the catalytically competent species from the commercially available latex of the tropical treeCarica papaya L. Their free thiol function (cysteine-25), which is essential for activity, was protected in the form of a mixed disulfide containing a 5 kDa polyethylene glycol (PEG) chain. The second (nonessential) free thiol function (cysteine-117) of chymopapain was blocked similarly. Caricain was also derivatized through acylation of its amino functions by PEG chains (average: 15 moles of PEG per mole of enzyme). The Chromatographic behavior of these conjugates was examined on ion-exchange and hydrophobic gels and compared to the Chromatographic behavior of the unpegylated proteinases. The results indicated that charge-shielding effects by PEG chain(s), surrounding the different proteinases, plays(play) a key role in the course of separation of pegylated and unpegylated species by ion-exchange chromatography. Similarly, PEG chain(s) is(are) able to mask hydrophobic regions on the surface of the proteinases. However, the affinity showed by PEG itself for the hydrophobic ligands immobilized on the matrix is the preponderant factor determining the behavior of the PEG-proteinases conjugates on Fractogel TSKButyl-650. 相似文献
37.
38.
Zoidis G Tsotinis A Kolocouris N Kelly JM Prathalingam SR Naesens L De Clercq E 《Organic & biomolecular chemistry》2008,6(17):3177-3185
Adamantanopyrrolidines 8, 9 and 10, adamantanopyrrolidines 16 and 18, adamantanoxazolone 20, adamantanopyrazolone 23, adamantanopyrazolothione 24 and adamantanocyclopentanamine 32 were synthesized and tested for anti-influenza A virus and trypanocidal activity. The stereoelectronic requirements for optimal antiviral and trypanocidal potency were investigated. Pyrrolidine 16 proved to be the most active of the compounds tested against influenza A virus, being 4-fold more active than amantadine, equipotent to rimantadine and 19-fold more potent than ribavirin. Oxazolone 20 showed significant trypanocidal activity against bloodstream forms of the African trypanosome, Trypanosoma brucei, being approximately 3 times more potent than rimantadine and almost 50-fold more active than amantadine. 相似文献
39.
Metal-catalysed transformations are a powerful tool in organic chemistry and the enormous progress, which has been made in the last few decades, was one more time honoured by the Nobel Prize in Chemistry in 2010. Many metal-containing compounds have been applied in carbon-carbon and carbon-heteroatom bond formations. However, not every component originally claimed as catalyst turned out to be the active ingredient in the end. Sometimes trace metal impurities were the actual catalytic species. In this tutorial review, we will highlight recent findings in transition metal-catalysed cross-coupling reactions and detail several reports from the past, which illustrate that "trace metal catalysis" is not a newly discovered phenomenon. 相似文献
40.
We report upper critical field B(c2)(T) measurements on a single-crystalline sample of the ferromagnetic superconductor UCoGe. B(c2)(0) obtained for fields applied along the orthorhombic axes exceeds the Pauli limit for B parallela,b and shows a strong anisotropy B(c2)(a) approximately B(c2)(b)>B(c2)(c). This provides evidence for an equal-spin pairing state and a superconducting gap function of axial symmetry with point nodes along the c axis, which is also the direction of the uniaxial ferromagnetic moment m(0)=0.07micro(B). An unusual curvature or kink is observed in the temperature variation of B(c2) which possibly indicates UCoGe is a two-band ferromagnetic superconductor. 相似文献