全文获取类型
收费全文 | 171篇 |
免费 | 13篇 |
出版年
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 26篇 |
2012年 | 5篇 |
2011年 | 9篇 |
2010年 | 6篇 |
2009年 | 10篇 |
2008年 | 3篇 |
2007年 | 7篇 |
2006年 | 6篇 |
2005年 | 6篇 |
2004年 | 10篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 9篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1968年 | 1篇 |
排序方式: 共有184条查询结果,搜索用时 15 毫秒
41.
Removal of bacterial suspension water occupying the intercellular space of detached leaves after agroinfiltration improves the yield of recombinant hemagglutinin in a Nicotiana benthamiana transient gene expression system
下载免费PDF全文
![点击此处可从《Biotechnology and bioengineering》网站下载免费的PDF全文](/ch/ext_images/free.gif)
42.
The substrate specificity of carboxypeptidase (F-II) purified from watermelon for various synthetic peptides and esters was examined kinetically. The enzyme showed a broad substrate specificity against various carbobenzoxy- and benzyl-dipeptides. Peptides containing glycine or proline were hydrolyzed slowly by the enzyme. Peptides containing hydrophobic amino acids were hydrolyzed rapidly. The presence of hydrophobic amino acid residues, not only at the C-terminal position but also at the second position and probably the third position from the C-terminal resulted in an increase in the rate of hydrolysis. Inhibition studies with diisopropyl flurophosphate and diastereomers of carbobenzoxy-Phe-Ala demonstrated that the peptidase and esterase activities of the enzyme are both catalyzed by the same site of the enzyme molecule, but the binding sites for peptides and esters seem not to be the same. The enzyme also had amidase activity, which was optimal at pH 7.0. 相似文献
43.
44.
Identification of unconjugated bile acids in human bile 总被引:1,自引:0,他引:1
Unconjugated bile acids in the bile of healthy and diseased humans were determined qualitatively and quantitatively by means of gas-liquid chromatography and gas-liquid chromatography-mass spectrometry, after their isolation by ion-exchange chromatography. In a healthy person and three patients with cholelithiasis, unconjugated bile acids comprised 0.1-0.4% of total biliary bile acids. The bile acid composition of the unconjugated fraction was quite different from that of the glycine- or taurine-conjugate fraction, in that it contained a relatively large proportion of unusual bile acids including C23 and C27 bile acids. In two patients with cerebrotendinous xanthomatosis, C22 and C23 bile acids were the major constituents of the biliary unconjugated bile acids, and comprised about 0.8% of total bile acids; no detectable amounts of C27 bile acids were found in their bile. The analysis of biliary unconjugated bile acids may be useful for the diagnosis of metabolic diseases concerning bile acids, particularly the accumulation or disappearance of unusual bile acids. 相似文献
45.
Influence of ionic composition,buffering agent,and pH on the histochemical demonstration of myofibrillar actomyosin ATPase 总被引:1,自引:0,他引:1
Summary The influence of the composition of the preincubation medium on the histochemical demonstration of myofibrillar actomyosin
ATPase, including a variety of carboxylic acid and non-carboxylic acid buffering compounds and neutral salts, was studied.
In inorganic salt-free systems the rate of the activation of type I fibers and inactivation of type II fibers was accelerated
when the carboxylic acids had longer chain length or multiple carobxyl groups. Of these factors, the number of carboxyl groups
was dominant with a 100 mM citrate buffer producing a sharp differentiation between fiber types. In contrast, the time course
of the response was exceptionally long in an acetate buffer. The time course of the ATPase reaction was also modified by other
buffers at pH 4.60. The most notable were an ascorbate — glycine buffer system which produced little or no deviation from
the alkaline preincubation staining pattern after prolonged preincubation and a pyrophosphate system which produced a rapid
change. Neutral salts in the preincubation medium accelerated the time course of the inactivation — activation process with
the order for the halogen salts of K+ being F−<Cl−<Br−<I−, which is a progression by molecular weight. The only sequence for cations on the myofibrillar actomyosin ATPase was Li+< Na+<K+. The response to salts was concentration dependent. An interaction existed between buffering compound, type of salt, and
pH. These experiments demonstrate that the histochemical differentiation of fiber types by the myofibrillar actomyosin ATPase
reaction depends upon a modification of some component(s) of the myofibrillar complex that can be influenced by a number of
factors. 相似文献
46.
47.
Kana Sugimoto Hidekazu Tanaka Hiroshi Ochi Ryoji Matoba 《Biochemical and biophysical research communications》2009,390(4):1214-1807
Methamphetamine induces several cardiac dysfunctions, which leads to arrhythmia, cardiac failure and sudden cardiac death. Although these cardiac alterations elicited by methamphetamine were thought to be due to an indirect action of methamphetamine, namely, an excessive catecholamine release from synaptic terminals, while it seems likely that methamphetamine directly modulates the functioning of cardiomyocytes independent of neurotransmitters. However, the direct effects of methamphetamine on cardiomyocytes are still not clear. We show that methamphetamine directly accelerates the beating rate and alters Ca2+ oscillation pattern in cultured neonatal rat cardiomyocytes. Adrenergic receptor antagonists did not block the methamphetamine-induced alterations in cardiomyocytes. Treatment with a ryanodine receptor type 2 inhibitor and a sarcoplasmic reticulum Ca2+-ATPase inhibitor did not affect these responses, either. In contrast, the L-type Ca2+ channel inhibitor nifedipine eradicated these responses. Furthermore, methamphetamine elevated the internal free Ca2+ concentration in HEK-293T cells stably transfected with the L-type Ca2+ channel α1C subunit. In neonatal rat cardiomyocytes, methamphetamine accelerates beating rate and alters Ca2+ oscillation pattern by increasing Ca2+ entry via the L-type Ca2+ channels independent of any neurotransmitters. 相似文献
48.
Catalytic Mechanism of Bleomycin N-Acetyltransferase Proposed on the Basis of Its Crystal Structure 总被引:1,自引:0,他引:1
Kosuke Oda Yasuyuki Matoba Masafumi Noda Takanori Kumagai Masanori Sugiyama 《The Journal of biological chemistry》2010,285(2):1446-1456
Bleomycin (Bm) N-acetyltransferase, BAT, is a self-resistance determinant in Bm-producing Streptomyces verticillus ATCC15003. In our present study, we crystallized BAT under both a terrestrial and a microgravity environment in the International Space Station. In addition to substrate-free BAT, the crystal structures of BAT in a binary complex with CoA and in a ternary complex with Bm and CoA were determined. BAT forms a dimer structure via interaction of its C-terminal domains in the monomers. However, each N-terminal domain in the dimer is positioned without mutual interaction. The tunnel observed in the N-terminal domain of BAT has two entrances: one that adopts a wide funnel-like structure necessary to accommodate the metal-binding domain of Bm, and another narrow entrance that accommodates acetyl-CoA (AcCoA). A groove formed on the dimer interface of two BAT C-terminal domains accommodates the DNA-binding domain of Bm. In a ternary complex of BAT, BmA2, and CoA, a thiol group of CoA is positioned near the primary amine of Bm at the midpoint of the tunnel. This proximity ensures efficient transfer of an acetyl group from AcCoA to the primary amine of Bm. Based on the BAT crystal structure and the enzymatic kinetic study, we propose that the catalytic mode of BAT takes an ordered-like mechanism. 相似文献
49.
50.
Purification and characterization of the second Streptomyces phospholipase A2 refolded from an inclusion body 总被引:2,自引:0,他引:2
Jovel SR Kumagai T Danshiitsoodol N Matoba Y Nishimura M Sugiyama M 《Protein expression and purification》2006,50(1):82-88
A secreted phospholipase A(2) (PLA(2)) from Streptomyces violaceoruber A-2688, previously identified by us, is the first PLA(2) identified in prokaryotes. Genome sequence data of Streptomyces coelicolor A3(2) indicates that the bacterium carries two genes encoding hypothetical PLA(2)s, which exhibit 100 and 78% identity, respectively, to the S. violaceoruber PLA(2). In this study, we named the former and latter proteins as the first and second PLA(2)s, respectively. When the second PLA(2) was expressed in Escherichia coli cells, it formed an inclusion body. The present study demonstrates a method to purify it to homogeneity without the disappearance of the enzymatic activity: the inclusion body was washed with sodium deoxycholate and dissolved in the presence of 2 M urea at pH 12, then refolded by the dilution method. The refolding of enzyme was confirmed by the circular dichroism spectrum. The second PLA(2) purified to homogeneity had the same specific activity as that of the S. violaceoruber PLA(2) and the yield was approximately 6.8 mg/L culture. The second PLA(2) exhibits similar enzymatic properties to the S. violaceoruber PLA(2), except that the former enzyme does not utilize phophatidic acid as a substrate. The surface electrostatic potential of the S. coelicolor PLA(2) model, which is created by the computer-homology modeling, suggests that the positively charged surface of the enzyme does not affect the substrate specificity. 相似文献