全文获取类型
收费全文 | 618篇 |
免费 | 48篇 |
出版年
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 25篇 |
2014年 | 15篇 |
2013年 | 27篇 |
2012年 | 23篇 |
2011年 | 26篇 |
2010年 | 15篇 |
2009年 | 15篇 |
2008年 | 22篇 |
2007年 | 33篇 |
2006年 | 15篇 |
2005年 | 10篇 |
2004年 | 21篇 |
2003年 | 23篇 |
2002年 | 13篇 |
2001年 | 24篇 |
2000年 | 25篇 |
1999年 | 17篇 |
1998年 | 5篇 |
1997年 | 13篇 |
1996年 | 11篇 |
1995年 | 12篇 |
1994年 | 5篇 |
1993年 | 9篇 |
1992年 | 13篇 |
1991年 | 14篇 |
1990年 | 10篇 |
1989年 | 19篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1973年 | 7篇 |
1971年 | 7篇 |
1966年 | 4篇 |
1938年 | 4篇 |
排序方式: 共有666条查询结果,搜索用时 15 毫秒
171.
172.
Laetitia Sabatier Daliang Chen Christine Fagotto-Kaufmann Dirk Hubmacher Marc D. McKee Douglas S. Annis Deane F. Mosher Dieter P. Reinhardt 《Molecular biology of the cell》2009,20(3):846-858
Fibrillins constitute the major backbone of multifunctional microfibrils in elastic and nonelastic extracellular matrices. Proper assembly mechanisms are central to the formation and function of these microfibrils, and their properties are often compromised in pathological circumstances such as in Marfan syndrome and in other fibrillinopathies. Here, we have used human dermal fibroblasts to analyze the assembly of fibrillin-1 in dependence of other matrix-forming proteins. siRNA knockdown experiments demonstrated that the assembly of fibrillin-1 is strictly dependent on the presence of extracellular fibronectin fibrils. Immunolabeling performed at the light and electron microscopic level showed colocalization of fibrillin-1 with fibronectin fibrils at the early stages of the assembly process. Protein-binding assays demonstrated interactions of fibronectin with a C-terminal region of fibrillin-1, -2, and -3 and with an N-terminal region of fibrillin-1. The C-terminal half of fibrillin-2 and -3 had propensities to multimerize, as has been previously shown for fibrillin-1. The C-terminal of all three fibrillins interacted strongly with fibronectin as multimers, but not as monomers. Mapping studies revealed that the major binding interaction between fibrillins and fibronectin involves the collagen/gelatin-binding region between domains FNI6 and FNI9. 相似文献
173.
Alex G. McKee Jennifer S. Loscher Niamh C. O’Sullivan Naomi Chadderton Arpad Palfi Laura Batti Graham K. Sheridan Sean O’Shea Mary Moran Olive McCabe Alfonso Blanco Fernández Menelas N. Pangalos John J. O’Connor Ciaran M. Regan William T. O’Connor Peter Humphries G. Jane Farrar Keith J. Murphy 《Journal of neurochemistry》2010,112(4):991-1004
174.
Brown BK Cox J Gillis A VanCott TC Marovich M Milazzo M Antonille TS Wieczorek L McKee KT Metcalfe K Mallory RM Birx D Polonis VR Robb ML 《PloS one》2010,5(11):e13849
Background
The fatal disease caused by Bacillus anthracis is preventable with a prophylactic vaccine. The currently available anthrax vaccine requires a lengthy immunization schedule, and simpler and more immunogenic options for protection against anthrax are a priority for development. In this report we describe a phase I clinical trial testing the safety and immunogenicity of an anthrax vaccine using recombinant Escherichia coli-derived, B. anthracis protective antigen (rPA).Methodology/Principal Findings
A total of 73 healthy adults ages 18–40 were enrolled and 67 received 2 injections separated by 4 weeks of either buffered saline placebo, or rPA formulated with or without 704 µg/ml Alhydrogel® adjuvant in increasing doses (5, 25, 50, 100 µg) of rPA. Participants were followed for one year and safety and immunologic data were assessed. Tenderness and warmth were the most common post-injection site reactions. No serious adverse events related to the vaccine were observed. The most robust humoral immune responses were observed in subjects receiving 50 µg of rPA formulated with Alhydrogel® with a geometric mean concentration of anti-rPA IgG antibodies of 283 µg/ml and a toxin neutralizing geometric 50% reciprocal geometric mean titer of 1061. The highest lymphoproliferative peak cellular response (median Lymphocyte Stimulation Index of 29) was observed in the group receiving 25 µg Alhydrogel®-formulated rPA.Conclusions/Significance
The vaccine was safe, well tolerated and stimulated a robust humoral and cellular response after two doses.Trial Registration
ClinicalTrials.gov NCT00057525相似文献175.
Strayer DS Agrawal L Cordelier P Liu B Louboutin JP Marusich E McKee HJ Ren CN Strayer MS 《Molecular biotechnology》2006,34(2):257-270
Among the goals of gene therapy is long-term expression of delivered transgenes. Recombinant Tag-deleted SV40 vectors (rSV40s) are especially well suited for this purpose. rSV40s deliver transgene expression that endures
for extended periods of time in tissue culture and in vivo, in both dividing and nondividing cells. These vectors are particularly
effective in transducing some cell types that have been almost unapproachable using other gene delivery systems, such as quiescent
hematopoietic progenitor cells and their differentiated derivatives. Other cellular targets include neurons, brain microglia,
hepatocytes, dendritic cells, vascular endothelium, and others. Because rSV40s do not elicit neutralizing antibodies they
are useful for in vivo gene delivery in settings where more than one administration may be desirable. The key characteristics
of these vectors include their high production titers and therefore suitability for large cell pools, effectiveness in delivering
intracellular proteins, and untranslated RNAs, maintenance of transgene expression at constant levels for extended times,
suitability for constitutive or conditional promoters and for combinatorial gene delivery and ability to integrate into genomes
of both dividing and nondividing cells. 相似文献
176.
177.
Upon entering mammalian cells, Pseudomonas exotoxin A (PE) is proteolytically processed by furin to produce an N-terminal fragment of 28 kDa and a C-terminal fragment of 37 kDa. Cleavage is followed by the reduction of a key disulfide bond (cysteines 265-287). This combination of proteolysis and reduction releases the 37 kDa C-terminal fragment, which then translocates to the cytosol where it ADP-ribosylates elongation factor 2 and inhibits protein synthesis. To investigate toxin reduction, furin-nicked PE or a hypercleavable mutant, PEW281A, was subjected to various treatments and then analyzed for fragment production. Reduction was evident only when unfolding conditions and a reducing agent were applied. Thermal unfolding of PE, as evidenced by changes in alpha-helical content and increased sensitivity to trypsin, rendered nicked toxin susceptible to protein disulfide isomerase- (PDI-) mediated reduction. When subcellular fractions from toxin-sensitive cells were incubated with nicked PE, toxin unfolding and reducing activities were present in the membrane fraction but not the soluble fraction. These data indicate that PE reduction is a two-step process: unfolding that allows access to the Cys265-287 disulfide bond, followed by reduction of the sulfur-sulfur bond by PDI or a PDI-like enzyme. With regard to cellular processing, we propose that the toxin's three-dimensional structure retains a "closed" conformation that restricts solvent access to the Cys265-287 disulfide bond until after a cell-mediated unfolding event. 相似文献
178.
179.
Expression of the 56-kDa B2 subunit isoform of the vacuolar H(+)-ATPase in proton-secreting cells of the kidney and epididymis 总被引:2,自引:0,他引:2
Paunescu TG Da Silva N Marshansky V McKee M Breton S Brown D 《American journal of physiology. Cell physiology》2004,287(1):C149-C162
B1 and B2 are two highly homologous isoforms of the vacuolar H+-ATPase (V-ATPase) 56-kDa B subunit. We investigated whether the B2 subunit is expressed alongside B1 in proton-secreting cells of the rodent kidney collecting duct (intercalated cells, IC) and epididymis (clear cells) by using antibodies against distinct COOH-terminal peptides from the two B isoforms. B2 was detected not only in the kidney proximal tubule, thick ascending limb, distal convoluted tubule, and connecting segment but also in A- and B-type IC of collecting ducts (CD) in both rat and mouse. B2 had a predominant cytoplasmic localization in most IC but was clearly located in a tighter apical band together with the V-ATPase 31-kDa E subunit in some A-IC, especially in the medulla. Apical membrane staining was confirmed by immunogold electron microscopy. B2 was very weakly expressed on the basolateral membranes of B-IC in control kidney CD, but some connecting segment B-IC had more distinct basolateral staining. In response to chronic carbonic anhydrase inhibition by acetazolamide, many A-IC showed a strong apical membrane localization of B2, where it colocalized with E and B1. In rat and mouse epididymis, B2 isoform expression was detected in clear cells, where it was concentrated in subapical vesicles. Unlike B1, B2 did not colocalize with the E subunit in the apical microvilli. These findings indicate that in addition to its role in the acidification of intracellular organelles, the B2 isoform could also contribute to transepithelial proton secretion and the maintenance of acid-base homeostasis. vacuolar H+-ATPase B subunit; intercalated cells; clear cells; urogenital tract; immunofluorescence 相似文献
180.
There is currently considerable interest in using mainly solid reaction mixtures for enzymic catalysis. In these reactions starting materials dissolve into, and product materials crystalize out of, a small amount of liquid phase in which the catalytic reaction occurs. An initial mathematical model for mass transfer effects in such systems is constructed using some physically reasonable approximations. The model equations are solved numerically to determine how the reactant concentrations vary with time and position. To evaluate the extent to which mass transfer limits the overall rate of product formation, an effectiveness factor is defined as the ratio of the observed total reaction rate to the total reaction rate in the reaction limited limit. As expected, the value of the effectiveness factor in steady state is strongly dependent on the Thiele modulus. However, it is also observed that the effectiveness factor can vary widely as a result of changes in the other dimensionless groups characterizing the system. For example, there are situations with Thiele modulus equal to unity in which the value of the effectiveness factor varies between approximately 0.1 and 0.8 as the other parameters are varied in physically reasonable ranges. Analytical asymptotic solutions that provide good approximations to the numerically calculated results in various physically important limiting cases are also presented. 相似文献