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排序方式: 共有5558条查询结果,搜索用时 15 毫秒
31.
Bin XIN Dan PU Shao Xiang XIONG* Guang Hui WANG Beijing Mass Spectrometry Center Center for Molecular Science Institute of Chemistry Chinese Academy of Sciences Beijing 《中国化学快报》2003,14(2)
Recently, capillary electrophoresis/electrospray ionization mass spectrometry (CE/ESI- MS) has been rapidly developed as a powerful analytical tool for charged species ranged from small molecules such as carboxylic acids1, phenolic compounds2, metal species3, tetramines4, herbicides5, drugs and drug metabolites6 to peptides and proteins7, 8. The ESI mode has proven to be sensitive, versatile and relatively easy to use in combination with CE. CE confers rapid analysis and efficient separ… 相似文献
32.
Michel Talagrand 《Journal of Theoretical Probability》1992,5(2):327-331
Consider a (complex) Banach spaceX, such thatX CO, and vectors(X
i
)
i
ofX. Consider an independent standard normal sequence(g
i
)
i
. Then if anX-valued random Fourier series |k|
n
e
ikt
g
k
x
k
satisfies
相似文献
33.
Eric S. Key 《Journal of Theoretical Probability》1992,5(2):375-389
Suppose thatX
1,X
2,... is a sequence of iid random variables taking values inZ
+. Consider the random sequenceA(X)(X
1,X
2,...). LetY
n
be the number of integers which appear exactly once in the firstn terms ofA(X). We investigate the limit behavior ofn
–(1–)
Y
n
for [0, 1]. 相似文献
34.
Consider a simple random walk on
d
whose sites are colored black or white independently with probabilityq, resp. 1–q. Walk and coloring are independent. Letn
k
be the number of steps by the walk between itskth and (k+1) th visits to a black site (i.e., the length of itskth white run), and let
k
=E(n
k
)–q
–1. Our main result is a proof that (*) lim
k
k
d/2
k
= (1 –q)q
d/2 – 2(d/2)
d/2. Since it is known thatq
– 1
k
=E(n
1
n
k + 1 B) –E(n
1 B)E(n
k + 1 B), withB the event that the origin is black, (*) exhibits a long-time tail in the run length autocorrelation function. Numerical calculations of
k
(1k100) ind=1, 2, and 3 show that there is an oscillatory behavior of
k
for smallk. This damps exponentially fast, following which the power law sets in fairly rapidly. We prove that if the coloring is not independent, but is convex in the sense of FKG, then the decay of
k
cannot be faster than (*). 相似文献
35.
Gerhard Wendlberger Liljana Mladenova-Orlinova Walter Göhring Regina Scharf Erich Wünsch 《Monatshefte für Chemie / Chemical Monthly》1981,112(11):1297-1312
The synthesis of the tetratriacontapeptide amide corresponding to the revised primary structure of human big gastrin I is described. For this purpose the fragments were designed in view of the maximum use of those utilized in our previous synthesis of human big gastrin I according to the first sequence proposal. Consequently the key tripeptide-Pro-Pro-His- (sequence 7–9) was prepared in suitably protected form to be used as amino or carboxyl component for assembly of the segments 1–9 and 1–14, respectively. Final condensation of the latter nona- and tetradecapeptide derivatives with the C-terminal segments 10–34 and 15–34 via the azide and the dicyclohexylcarbodiimide/N-hydroxysuccinimide procedure, respectively, leads to crude fully protected human big gastrin I. Upon deprotection by exposure to trifluoroacetic acid in presence of ethanedithiol-(1,2) as scavanger, ion exchange chromatography and partition chromatography, the desired tetratriacontapeptide amide was isolated in satisfactory yield with a high degree of purity. The identical immunological behaviour of the synthetic material, if compared with that of natural human big gastrin I, represents ulterior strong evidence for the correctness of the newly proposed structure for this putative prohormonal form of the gastrins.
Kurzmitteilung:Wünsch E., Wendlberger G., Mladenova-Orlinova L., Göhring W., Jaeger E., Scharf R., Gregory R. A., Dockray G. J., Hoppe-Seyler's Z. Physiol. Chem.362, 179 (1981). 相似文献 36.
《Arabian Journal of Chemistry》2022,15(12):104368
Protein hydrolysates have the potential to be natural and safer sources of bioactive peptides. In this study, two proteases were used to hydrolyze Chinese sturgeon (Acipenser sinensis) protein, and the hydrolysates were then purified to yield antioxidant peptides. The degree of hydrolysis of 23.56 % and 18.14 % was obtained using papain and alcalase 2.4L, respectivly, and hydrolysates had 96.80 % and 87.24 % total amino acid content, respectivly. The papain hydrolysate (PH) and alcalase 2.4L hydrolysate (AH) showed good antioxidant activity against DPPH? (IC50 of 3.64 and 3.15 mg/mL) and ABTS?+ (IC50 of 1.92 and 1.58 mg/mL), respectively. The low-molecular-weight (<1000 Da) fraction of both hydrolysates demonstrated the highest antiradical activity (IC50 of 2.59 and 2.31 mg/mL, DPPH) and (IC50 of 1.54 and 1.36 mg/mL, ABTS), respectively. Nine peptides were separated from both hydrolysates using reverse phase high performance liquid chromatography (RP-HPLC). The IC50 for ABTS?+ scavenging activity of peptide P5 with valine, glycine and asparagine (MW of 282.13 Da) from PH, and peptide P3 with histidine, glycine and alanine (MW of 302.74 Da) from AH was 0.89 and 0.72 mg/mL, respectively. The fractions and purified peptides obtained from Chinese sturgeon hydrolysates could be utilized as natural antioxidant substitutes in pharmaceuticals and food products. 相似文献
37.
Tushar K. Chakraborty B.Krishna MohanS.Kiran Kumar Ajit C. Kunwar 《Tetrahedron letters》2003,44(3):471-473
Synthesis and conformational studies of two short peptides containing pyrrole amino acids (1, Paa), Boc-Paa-Paa-d-Pro-Gly-Xaa-Paa-Paa-OMe (2: Xaa=Ala; 3: Xaa=Val), were carried out in which it was established that replacement of Ala in 2 with a Val residue helps peptide 3 to adopt a well-defined β-hairpin conformation in a nonpolar solvent, like CDCl3. 相似文献
38.
In spite of Sinai's result that the decay of the velocity autocorrelation function for a random walk on
d
(d=2) can drastically change if local impurities are present, it is shown that local impurities can not abolish weak convergence to the Brownian motion if d2. 相似文献
39.
40.
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