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   35篇
  免费   2篇
  2017年   1篇
  2016年   1篇
  2015年   1篇
  2014年   2篇
  2013年   4篇
  2012年   1篇
  2010年   2篇
  2009年   1篇
  2007年   1篇
  2006年   1篇
  2005年   1篇
  2004年   2篇
  2002年   1篇
  1999年   2篇
  1997年   1篇
  1996年   1篇
  1994年   1篇
  1993年   2篇
  1992年   1篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1984年   3篇
  1983年   1篇
  1980年   1篇
  1978年   1篇
  1968年   1篇
排序方式: 共有37条查询结果,搜索用时 0 毫秒
21.

Background  

Tuberculosis (TB) is a major health problem and HIV is the major cause of the increase in TB. Sub-Saharan Africa is endemic for both TB and HIV infection. Determination of the prevalence of M. tuberculosis strains and their drug susceptibility is important for TB control.  相似文献   
22.

Background  

Heterologous prime-boost immunization protocols using different gene expression systems have proven to be successful tools in protecting against various diseases in experimental animal models. The main reason for using this approach is to exploit the ability of expression cassettes to prime or boost the immune system in different ways during vaccination procedures. The purpose of the project was to study the ability of recombinant vaccinia virus (VV) and bacterial plasmid, both carrying the NS1 gene from tick-borne encephalitis (TBE) virus under the control of different promoters, to protect mice against lethal challenge using a heterologous prime-boost vaccination protocol.  相似文献   
23.
24.
The proteolytic activity of an alkalophilic Bacillus sp. (NCL 87-6-10) correlates with xylanase secretion. Addition of DL-norvaline, glycine or Casamino acids to a medium formulated for xylanase production resulted in 2-5-fold enhancement of xylanase secretion (8 to 45 IU/ml). Inhibition of proteolytic activity is a possible mechanism for enhanced xylanase activity.  相似文献   
25.
Summary The feral pigeon in New York City was found to serve as a mechanical carrier of pathogenic strains ofCryptococcus neoformans. Of 94 feral pigeons freshly trapped in the city, 7 were found to carryC. neoformans on their beaks and feet, while their rectal swabs were negative. Following crop instillation ofC. neoformans in 3 feral pigeons, the fungus survived passage through the gastrointestinal tract and appeared in the fresh feces within one hour after inoculation and was still present 24 hours later. The internal body (rectal) temperatures of 57 feral pigeons recorded soon after capture in two seasons of the year, ranged from 41.5° C to 43.3° C and averaged 42.5° ± 0.39° C. The birds were able to maintain their high temperatures in the face of sustained cold, indicating the presence of a strong thermoregulating mechanism. A study of the growth and survival of 60 human strains ofC. neoformans on Sabouraud dextrose yeast extract agar slants revealed that 100 % of the cultures were able to grow at 39° C, 92 % at 40° C, 30 % at 41° C, 17 % at 42° C and 8 % at 43° C. Despite exposure to these temperatures for 7 days, 100 % of the human strains survived at 40° C, 97 % at 41° C, 95 % at 42° C, 91 % at 43° C, 88 % at 44° C, 47 % at 45° C and none at 47° C. Seventy strains ofC. neoformans of pigeon excreta origin showed a similar pattern of heat resistance, except that 11 % of these strains survived 47° C. The inability ofC. neoformans to grow at 44° C, a property shared by all 130 strains, provides a new species characteristic.C. neoformans was found to multiply rapidly in moist pigeon excreta extract, reaching counts up to 60 million per ml within 3 weeks, and to be still viable in moist as well as dessicated pigeon excreta extract after more than two years of storage at room temperature.Presented in part at the 26th VA-Armed Forces Pulmonary Disease Research Conference, Cleveland, Ohio, Jan. 23–26, 1967, and the 67th Annual Meeting American Society for Microbiology, New York, April 30–May 4, 1967. Supported by Grants GB-4722 from the National Science Foundation and U-1367 from The Health Research Council of the City of New York.Acknowledgment is gratefully given toThomas J. Dalton, Division of Environmental Sanitation, Department of Health, New York City andMabel Halloran for their valuable assistance and to the ASPCA of Manhattan and Brooklyn for their cooperation in this study.  相似文献   
26.
A method for the location of proteins/enzymes by polyacrylamide gel electrophoresis using dialyzable low-molecular-weight fluorescent peptide markers is described. The markers prepared by treating the peptic digest of casein with fluorescamine showed several bands on gel electrophoresis which helped in locating the proteins. The located desired protein could subsequently be purified by extraction.  相似文献   
27.
An alkalophilicBacillus (NCL-87-6-10, NCIM 2128), with a high productivity for extracellular xylanase (EC 3.2.1.8) and free of cellulase, was isolated from soil containing coconut fibre detritus. When grown on a wheat bran/yeast extract medium in submerged culture for 48 h, it produced 100 to 120 IU of enzyme activity per ml. The crude enzyme consists of two fractions of apparent mol sizes of approx 10.4 and 29 kDa in the proportion of 90:10, as determined by native gel exclusion chromatography. Optimum activity of the xylanase was at 60°C and pH 8.0. A two-fold increase in enzyme activity was obtained when reducing agents, thioethanol and dithiothreitol, were included in the assay.NCL Communication No. 5381.  相似文献   
28.

Background  

Some diseases, like tumors, can be related to chromosomal aberrations, leading to changes of DNA copy number. The copy number of an aberrant genome can be represented as a piecewise constant function, since it can exhibit regions of deletions or gains. Instead, in a healthy cell the copy number is two because we inherit one copy of each chromosome from each our parents.  相似文献   
29.
This article reports on the optical properties of 0.5% mol of Sm3+, Dy3+ ion‐doped B2O3‐TeO2‐Li2O‐AlF3 (LiAlFBT) glasses. The glass samples were characterized by optical absorption and emission spectra. Judd‐Ofelt theory was applied to analyze the optical absorption spectra and calculate the intensity parameters and radiative properties of the emission transitions. The emission spectra of Sm3+ and Dy3+:LiAlFBT glasses showed a bright reddish‐orange emission at 598 nm (4G5/26H7/2) and an intense yellow emission at 574 nm (4F9/26H13/2), respectively. Full width at half maximum (FWHM), stimulated emission cross section, gain bandwidth and optical gain values were also calculated to extend the applications of the Sm3+ and Dy3+:LiAlFBT glasses. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
30.
The protein kinase PINK1 was recently shown to phosphorylate ubiquitin (Ub) on Ser65, and phosphoUb activates the E3 ligase Parkin allosterically. Here, we show that PINK1 can phosphorylate every Ub in Ub chains. Moreover, Ser65 phosphorylation alters Ub structure, generating two conformations in solution. A crystal structure of the major conformation resembles Ub but has altered surface properties. NMR reveals a second phosphoUb conformation in which β5-strand slippage retracts the C-terminal tail by two residues into the Ub core. We further show that phosphoUb has no effect on E1-mediated E2 charging but can affect discharging of E2 enzymes to form polyUb chains. Notably, UBE2R1- (CDC34), UBE2N/UBE2V1- (UBC13/UEV1A), TRAF6- and HOIP-mediated chain assembly is inhibited by phosphoUb. While Lys63-linked poly-phosphoUb is recognized by the TAB2 NZF Ub binding domain (UBD), 10 out of 12 deubiquitinases (DUBs), including USP8, USP15 and USP30, are impaired in hydrolyzing phosphoUb chains. Hence, Ub phosphorylation has repercussions for ubiquitination and deubiquitination cascades beyond Parkin activation and may provide an independent layer of regulation in the Ub system.  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