全文获取类型
收费全文 | 66篇 |
免费 | 11篇 |
出版年
2017年 | 2篇 |
2016年 | 2篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 2篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 3篇 |
1999年 | 1篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有77条查询结果,搜索用时 31 毫秒
31.
32.
Twenty-two different yeasts were screened for their ability to ferment both glucose and cellobiose. The fermentation characteristics of Candida lusitaniae (NRRL Y-5394) and C. wickerhamii (NRRL Y-2563) were selected for further study because their initial rate of ethanol production from cellobiose was faster than the other test cultures. C. lusitaniae produced 44 g/L ethanol from 90 g/L cellobiose after 5-7 days. When higher carbohydrate concentrations were employed, fermentation ceased when the ethanol concentration reached 45-60 g/L. C. lusitaniae exhibited barely detectable levels of beta-glucosidase, even though the culture actively fermented cellobiose. C. wickerhamii produced ethanol from cellobiose at a rate equivalent to C. lusitaniae; however, once the ethanol concentration reached 20 g/L, fermentation ceased. Using p-nitrophenyl-beta-D-glucopyranoside (pNPG) as substrate, beta-glucosidase (3-5 U/mL) was detected when C. wickerhamii was grown anaerobically on glucose or cellobiose. About 35% of the beta-glucosidase activity was excreted into the medium. The cell-associated activity was highest against pNPG and salicin. Approximately 100-fold less activity was detected with cellobiose as substrate. When empolying these organisms in a simultaneous saccharification-fermentation of avicel, using Trichoderma reesei cellulase as the saccharifying agent, 10-30% more ethanol was produced by the two yeasts capable of fermenting cellobiose than by the control, Saccharomyces cerevisiae. 相似文献
33.
H?Bukulmez AL?Matthews CM?Sullivan C?Chen MJ?Kraay RC?Elston RW?Moskowitz VM?Goldberg ML?WarmanEmail author 《Arthritis research & therapy》2005,8(1):R25
In order to determine whether there is a genetic component to hip or knee joint failure due to idiopathic osteoarthritis (OA),
we invited patients (probands) undergoing hip or knee arthroplasty for management of idiopathic OA to provide detailed family
histories regarding the prevalence of idiopathic OA requiring joint replacement in their siblings. We also invited their spouses
to provide detailed family histories about their siblings to serve as a control group. In the probands, we confirmed the diagnosis
of idiopathic OA using American College of Rheumatology criteria. The cohorts included the siblings of 635 probands undergoing
total hip replacement, the siblings of 486 probands undergoing total knee replacement, and the siblings of 787 spouses. We
compared the prevalence of arthroplasty for idiopathic OA among the siblings of the probands with that among the siblings
of the spouses, and we used logistic regression to identify independent risk factors for hip and knee arthroplasty in the
siblings. Familial aggregation for hip arthroplasty, but not for knee arthroplasty, was observed after controlling for age
and sex, suggesting a genetic contribution to end-stage hip OA but not to end-stage knee OA. We conclude that attempts to
identify genes that predispose to idiopathic OA resulting in joint failure are more likely to be successful in patients with
hip OA than in those with knee OA. 相似文献
34.
Structure and regulation of the anthranilate synthase genes in Pseudomonas aeruginosa: II. Cloning and expression in Escherichia coli 总被引:7,自引:0,他引:7
Crawford IP; Wilde A; Yelverton EM; Figurski D; Hedges RW 《Molecular biology and evolution》1986,3(5):449-458
The genes for the large and small subunits of anthranilate synthase (trpE
and trpG, respectively) have been cloned from Pseudomonas aeruginosa PAC174
into E. coli by R-prime formation with the broad-host- range plasmid
R68.44. Sequential subcloning into plasmid vectors reduced the active
Pseudomonas DNA fragment to a length of 3.1 kb. We obtained evidence that
this region contains the promoter for its own expression and retains a
vestigial regulatory response to tryptophan scarcity or excess.
相似文献
35.
RW Dapson 《Biotechnic & histochemistry》2016,91(8):522-531
During the 1860’s, Hugo Schiff studied many reactions between amines and aldehydes, some of which have been used in histochemistry, at times without credit to Schiff. Much controversy has surrounded the chemical structures and reaction mechanisms of the compounds involved, but modern analytical techniques have clarified the picture. I review these reactions here. I used molecular modeling software to investigate dyes that contain primary amines representing eight chemical families. All dyes were known to perform satisfactorily for detecting aldehydes in tissue sections. The models verified the correct chemical structures at various points in their reactions and also determined how decolorization occurred in those with “leuco” forms. Decolorization in the presence of sulfurous acid can occur by either adduction or reduction depending on the dye. The final condensation product with aldehyde was determined to be either a C-sulfonic acid adduct on the carbonyl carbon atom or an aminal at the same atom. Based on the various outcomes, I have placed the dyes and their reactions into five categories. Because Hugo Schiff studied the reactions between aldehydes and amines with and without various acids or alcohol, it is only proper to call each of them Schiff reactions that used various types of Schiff reagents. 相似文献
36.
Secondary biosynthesis of aflatoxin B in Aspergillus parasiticus 总被引:4,自引:0,他引:4
37.
38.
RW Dapson 《Biotechnic & histochemistry》2013,88(3):133-140
Although the mechanics of formalin fixation and antigen retrieval have been studied extensively and reviewed periodically, little attention has been directed toward conformational changes in target molecules. Formaldehyde changes the shape of tissue molecules by appending small hydroxymethyl groups to them. These adducts, in turn, can react with other tissue molecules to form crosslinks, or they can participate in a variety of reactions during tissue processing, including formation of imines, ethoxymethyl adducts, and further crosslinks. Under the influence of alcohol dehydration, fixed DNA may fragment and form a variety of depurination products. The situation becomes even more complex with short fixation times because under these conditions, the dehydrating agent used for tissue processing denatures macromolecules in other ways, most notably through rearrangement of molecular shape to move hydrophobic realms outward and hydrophilic areas inward (hydrophobic inversions). How tissue molecules are modified affects the outcome of immunohistochemical staining and prospects for restoration of antigenicity. Immunoreacitivity may be compromised because epitopes are either sterically hidden, but otherwise unaffected, or they have been altered more directly. Enzyme-based retrieval methods are best suited for the former because they literally snip the molecule apart to reveal the portions of interest. Heat-induced retrieval with buffers can demodify affected epitopes by removing adducts and breaking crosslinks. The choice of temperature and pH is usually critical for optimal retrieval. Effective temperatures are directly related to the strength of bonds-higher temperatures are needed to break stronger bonds. The pH of the retrieval solution determines the charge on the tissue molecule; the goal is to create a charge that causes the demodified molecule to assume a near natural conformation. Rational use of these concepts should lead to better control of immunohistochemical reactions. 相似文献
39.
In June 2008, the Biological Stain Commission sponsored A Seminar on Dyes and Staining the purpose of which was twofold: first, to show that very useful information applicable to biomedical dyes and staining is available from unrelated disciplines and second, to summarize modern thinking on how dyes, solvents, and tissues interact to produce selective staining. In this introduction to the papers from the symposium, we acknowledge that biomedical dye research has declined as newer technologies have gained importance. We should point out, however, that dyes and staining still are vitally important. Moreover, needs abound for innovative studies concerned with dye analysis, synthesis, and mode of action. Concepts and tools from unrelated fields hold promise for significant breakthroughs in many areas of interest. 相似文献
40.