首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   192篇
  免费   10篇
  2018年   1篇
  2016年   1篇
  2014年   2篇
  2013年   85篇
  2012年   7篇
  2011年   4篇
  2010年   2篇
  2008年   4篇
  2007年   2篇
  2006年   4篇
  2005年   4篇
  2004年   3篇
  2002年   3篇
  2001年   4篇
  2000年   4篇
  1999年   3篇
  1998年   2篇
  1994年   2篇
  1992年   5篇
  1990年   3篇
  1989年   3篇
  1988年   3篇
  1987年   3篇
  1986年   4篇
  1985年   4篇
  1984年   3篇
  1983年   2篇
  1982年   5篇
  1981年   4篇
  1980年   3篇
  1979年   4篇
  1978年   4篇
  1977年   3篇
  1976年   2篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1972年   2篇
  1970年   2篇
  1969年   2篇
  1968年   1篇
排序方式: 共有202条查询结果,搜索用时 15 毫秒
111.
In the screening of actinomycetes’ culture filtrate for inhibitor of subtilisin and various microbial alkaline proteinases, a novel inhibitor was found in a cultured broth of strain WT-27. This inhibitor was named as MAPI, abbreviation of microbial alkaline proteinase inhibitor.Judging from the morphological and physiological properties of the actinomycetes which produced MAPI, this strain was identified as Streptomyces nigrescens.

For the production of MAPI, this strain was aerobically cultured at 25 ~ 27%C in a jar fermentor which contained an optimum medium consisting of polypepton 3 %, meat extract 1%, glucose 1%, NaCl 0.1%, K2HPO4 0.1% and MnSO4·nH2O 0.0001%, pH 7.0. The production of MAPI reached its maximum after 21 ~ 24 hr cultivation.

MAPI had an inhibitory activity against various microbial alkaline proteinases, α-chymotrypsin and papain but not against trypsin, kallikrein, thermolysin, or pepsin.  相似文献   
112.
A novel enzyme, which was named Nα-benzyloxycarbonyl amino acid urethane hydrolase II, was purified from a cell-free extract of Lactobacillus fermenti 36 ATCC 9338. The enzyme catalyzed the stoichiometric hydrolysis of Nα-benzyloxycarbonyl arginine to form benzyl alcohol and arginine. The enzyme was purified 106-fold with an activity yield of 3%. The purified enzyme was homogeneous by disc gel electrophoresis. The molecular weight of the native enzyme is about 200,000 by gel filtration, and a molecular weight of 27,000 was found for the reduced and denaturated enzyme by gel electrophoresis in sodium dodecyl sulfate. The isoelectric point of the enzyme was 5.0, it was inhibited by disodium ethylenediamine tetraacetate and p-chloromercuribenzoate, and the presence of a divalent cation, i.e. Co2+, is essential for its activity.  相似文献   
113.
114.
Antibodies to Toxoplasma gondii were assayed by ELISA in 22 experimentally inoculated domestic ducks. In addition, a serological assay was carried out at Obihiro, Hokkaido, Japan, in 2004 and 2005, on 221 wild ducks of 5 species: Anas platyrhynchus (n = 111); A. poecilorhyncha (n = 27); A. acuta (n = 58); A. penelope (n = 16); and A. crecca (n = 9). Assays were also conducted using sera from 197 wild geese of 2 species, i.e., Anser albifrons (n = 162) and Ans. fabalis (n = 35). Birds were collected between 2003 and 2005 from 3 different areas: Lake Miyajima-numa, Hokkaido, Japan, regions around Anadyr city of Chukotka autonomous okrug, and Lake Makobetukoe, Kamchatka oblast, Russia. The ELISA cutoff value (OD) was > or =0.395 based on results from uninfected ducks; the final dilution ratio recognized as positive was represented by the end titer. The end titer in the experimentally infected ducks ranged from 1:400 to 1:3,200. Antibodies to T. gondii were found in 49 of the 221 wild duck samples from Japan: A. platyrhynchus (22/74); A. poecilorhyncha (2/15); A. penelope (3/16); A. acuta (4/58); and A. crecca (0/9), all in 2004. In 2005, T. gondii was found in A. platyrhynchus (13/37); and A. poecilorhyncha (5/12). Thirty-two of 197 wild goose samples were seropositive, i.e., Ans. albifrons (7/51) in 2004 and (11/72) in 2005 in Miyajima-numa, Japan and 9/39 in Chukotka, Russia as well as in Ans. fabalis (5/35) in Kamchatka, for which the end titer ranged from 1:100 to 1:3,200. In immunoblotting, the A. platyrhynchus samples showed specific IgG antibody binding to several antigens in the T. gondii lane, i.e., at 30 and 43 kDa, but not in the Neospora caninum lane. No specific bands were noted in samples for which antibody activity was not detected. These results suggest that wild waterfowl inhabiting Hokkaido, Chukotka, and Kamchatka may be exposed to T. gondii.  相似文献   
115.
The exchange reaction of the peptide NH protons of a microbial protease inhibitor (Streptomyces subtilisin inhibitor) with deuterium atoms in 2H2O (p2H 6.8) has been studied by proton magnetic resonance in the temperature range 56-71 degrees C. Both slowly and rapidly exchanging processes have been observed. The number of slowly exchanging protons is estimated to be 25 +/- 2 per subunit of the protein molecule. The decay of the slowly exchanging proton signals follows a single time-exponential function at each temperature. The observed first-order rate constants have been analyzed to give the denaturated fraction of the protein as a function of temperature with a consequent enthalpy (56 kcal/mol) and an entropy (137 cal/degree per mol) of denaturation. The results indicate the high conformational stability of this protein against heat denaturation.  相似文献   
116.
117.
118.
A tissue-type transglutaminase (TGase) was purified from liver tissue of the red sea bream, Pagrus major, by ion-exchange chromatography and heparin-Sepharose affinity chromatography. Its activity was assessed using a fluorometric assay to measure the incorporation of monodansylcadaverine into N,N′-dimethyl casein. The molecular mass of purified TGase was estimated to be 78kDa by SDS–polyacrylamide gel electrophoresis. The enzyme required Ca2+ to express its activity, although 10 mM Sr2+ also activated the enzyme fully. TGase activity was maximal at pH 9.0–9.5, and the enzyme was strongly inhibited by sulfhydryl reagents. The purified enzyme catalyzed the cross-linking of myosin heavy chain obtained from Alaska pollack, resulting in gelation of an actomyosin solution. The partial amino acid sequence of this fish TGase showed divisionally significant similarity to TGase from guinea pig liver.  相似文献   
119.
Conditions for extracellular production of vitamin B6 compounds (B6), especially pyridoxal 5'-phosphate (PLP) by Schizosaccharomyces pombe leu1 strain were examined. The productivity was dependent on concentration of L-leucine in the culture medium: 30 mg/l gave the highest concentrations of total B6 and PLP. The viable cells harvested at different growth phases showed different productivity: middle and late exponential phase cells showed the highest productivity of total B6 and PLP, respectively. D-Glucose (1%, w/v) among other sugars gave the best productivity. Supplementation of air and ammonium sulfate significantly increased extracellular production of PLP. Superoxide anion producers, menadione and plumbagin, and H2O2 increased the productivity of PLP. Cycloheximide inhibited the increase of PLP by the oxidative stress and in contrast, increased pyridoxine.  相似文献   
120.
S–PI inhibited various acid proteases including pepsin, Rhodotorula glutinis acid protease and Cladosporium acid protease, but the rate of inhibition was different for each acid protease.

S–PI made an equimolar complex with these acid proteases. A part of the enzyme-S–PI complex dissociated in the reaction mixture and showed proteolytic activity. The specific activity of the enzyme-S–PI complex depended on the concentration of the complex in the reaction mixture. Compared with native (S–PI free) enzyme, each of the enzyme-S–PI complex showed 50% activity at the following concentrations, pepsin; 7.5×10?10M, Rh. glutinis acid protease; 1.8×10?7M, Cladosporium acid protease; 3.0×10?6M.

These acid proteases were stabilized from heat or acid denaturation by making the enzyme-S–PI complex. S–PI protected the modification of these acid proteases by diazoacetyl-DL-norleucine methyl ester.

Binding between these acid proteases and S–PI dissociated at around neutral pH. S–PI was separated from enzyme-S–PI complex by dialysis at pH 7.5. In this case, pepsin underwent denaturation, while denaturations of Rh. glutinis acid protease and Cladosporium acid protease were slight. Rh. glutinis acid protease and Cladosporium acid protease were recovered from enzyme-S–PI complex by DEAE cellulose column chromatography as a native form.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号