全文获取类型
收费全文 | 254篇 |
免费 | 35篇 |
国内免费 | 3篇 |
出版年
2019年 | 3篇 |
2018年 | 7篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 13篇 |
2014年 | 17篇 |
2013年 | 11篇 |
2012年 | 8篇 |
2011年 | 15篇 |
2010年 | 9篇 |
2009年 | 13篇 |
2008年 | 13篇 |
2007年 | 9篇 |
2006年 | 8篇 |
2005年 | 5篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 4篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1996年 | 3篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 8篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 9篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1970年 | 4篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 3篇 |
1962年 | 2篇 |
1903年 | 1篇 |
排序方式: 共有292条查询结果,搜索用时 31 毫秒
1.
Cloning and sequencing of the peroxisomal amine oxidase gene from Hansenula polymorpha 总被引:7,自引:0,他引:7
P G Bruinenberg M Evers H R Waterham J Kuipers A C Arnberg G AB 《Biochimica et biophysica acta》1989,1008(2):157-167
We have cloned the AMO gene, encoding the microbody matrix enzyme amine oxidase (EC 1.4.3.6) from the yeast Hansenula polymorpha. The gene was isolated by differential screening of a cDNA library, immunoselection, and subsequent screening of a H. polymorpha genomic library. The nucleotide sequence of a 3.6 kilobase stretch of DNA containing the amine oxidase (AMO) gene was determined. The AMO gene contains an open reading frame of 692 amino acids, with a relative molecular mass of 77,435. The 5' and 3' ends of the gene were mapped and show that the transcribed region measures 2134 nucleotides. The derived amino-acid sequence was confirmed by sequencing an internal proteolytic fragment of the purified protein. Amine oxidase contains the tripeptide sequence Ser-Arg-Leu, located 9 residues from the carboxy terminus, which may represent the topogenic signal for protein import into microbodies. 相似文献
2.
3.
4.
Shawn Thatcher April Leonard Marianna Lauer Gayathri Panangipalli Bret Norman Zhenglin Hou Victor Llaca Wang-Nan Hu Xiuli Qi Jennifer Jaqueth Dina Severns David Whitaker Bill Wilson Girma Tabor Bailin Li 《Molecular Plant Pathology》2023,24(7):758-767
Northern corn leaf blight, caused by the fungal pathogen Exserohilum turcicum, is a major disease of maize. The first major locus conferring resistance to E. turcicum race 0, Ht1, was identified over 50 years ago, but the underlying gene has remained unknown. We employed a map-based cloning strategy to identify the Ht1 causal gene, which was found to be a coiled-coil nucleotide-binding, leucine-rich repeat (NLR) gene, which we named PH4GP-Ht1. Transgenic testing confirmed that introducing the native PH4GP-Ht1 sequence to a susceptible maize variety resulted in resistance to E. turcicum race 0. A survey of the maize nested association mapping genomes revealed that susceptible Ht1 alleles had very low to no expression of the gene. Overexpression of the susceptible B73 allele, however, did not result in resistant plants, indicating that sequence variations may underlie the difference between resistant and susceptible phenotypes. Modelling of the PH4GP-Ht1 protein indicated that it has structural homology to the Arabidopsis NLR resistance gene ZAR1, and probably forms a similar homopentamer structure following activation. RNA sequencing data from an infection time course revealed that 1 week after inoculation there was a threefold reduction in fungal biomass in the PH4GP-Ht1 transgenic plants compared to wild-type plants. Furthermore, PH4GP-Ht1 transgenics had significantly more inoculation-responsive differentially expressed genes than wild-type plants, with enrichment seen in genes associated with both defence and photosynthesis. These results demonstrate that the NLR PH4GP-Ht1 is the causal gene underlying Ht1, which represents a different mode of action compared to the previously reported wall-associated kinase northern corn leaf blight resistance gene Htn1/Ht2/Ht3. 相似文献
5.
Localized mutagenesis with bacteriophage Mu: method for increasing the frequency of specific bacterial mutants. 下载免费PDF全文
A method is described for markedly enriching a bacterial population for cells containing any given Mu insertion mutation. The method involves the transfer of a small piece of deoxyribonucleic acid from a Mu-infected Hfr donor donor strain to a suitable F- strain and a subsequent selection of those recombinant organisms that have received a Mu prophage from the donor. The method is particularly usefule for isolating mutants whose selection requires "brute-force" assay, since only a few hundred colonies have to be screened. 相似文献
6.
Improved Method for Determination of Respiring Individual Microorganisms in Natural Waters 总被引:29,自引:17,他引:12 下载免费PDF全文
A method is reported that combines the microscopic determinations of specific, individual, respiring microorganisms by the detection of electron transport system activity and the total number of organisms of an estuarine population by epifluorescence microscopy. An active cellular electron transport system specifically reduces 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) to INT-formazan, which is recognized as opaque intracellular deposits in microorganisms stained with acridine orange. In a comparison of previously described sample preparation techniques, a loss of >70% of the counts of INT-reducing microorganisms was shown to be due to the dissolution of INT-formazan deposits by immersion oil (used in microscopy). In addition, significantly fewer fluorescing microorganisms and INT-formazan deposits, both ≤0.2 μm in size, were found for sample preparations that included a Nuclepore filter. Visual clarity was enhanced, and significantly greater direct counts and counts of INT-reducing microorganisms were recognized by transferring microorganisms from a filter to a gelatin film on a cover glass, followed by coating the sample with additional gelatin to produce a transparent matrix. With this method, the number of INT-reducing microorganisms determined for a Chesapeake Bay water sample was 2-to 10-fold greater than the number of respiring organisms reported previously for marine or freshwater samples. INT-reducing microorganisms constituted 61% of the total direct counts determined for a Chesapeake Bay water sample. This is the highest percentage of metabolically active microorganisms of any aquatic population reported using a method which determines both total counts and specific activity. 相似文献
7.
Thioglycollate-elicited macrophages (m phi), upon binding the lectin Griffonia simplicifolia IB4 (GSIB4) at the plasma membrane, are induced to secrete several low molecular weight proteins. In this investigation, results from specific ELISA and immunoprecipitation analysis of these molecules confirmed that the cytokine, tumor necrosis factor-alpha (TNF-alpha), belongs to the group of elicited proteins. This specific m phi response is directly influenced by the dose of GSIB4 used and the time in contact with the cells. At 40 micrograms/ml GSIB4, the maximum dose of lectin used, the m phi activity was equal to that achieved when the cells were incubated with an interferon-gamma/lipopolysaccharide (IFN/LPS) stimulus alone. Moreover, the data showed that TNF-mediated tumoricidal activity was significantly influenced by GSIB4 binding to the m phi membrane. When the lectin was incubated alone or in sequence with IFN/LPS, this ligand-receptor binding promoted the lysis of WEHI 164 tumor target cells. However, concurrent incubation of both IFN/LPS and GSIB4 with m phi significantly diminished the tumoricidal response. This suggested that one of the metabolic pathways utilized subsequent to receptor-ligand binding was altered by these interactions. When cyclic AMP (cAMP) and inositol triphosphate (IP3) levels were examined, the results showed that the concentration of cAMP was unchanged despite the fact that IP3 levels were significantly enhanced upon m phi-GSIB4 binding. Collectively, the data show that GSIB4 binding to specific glycoproteins in the m phi membrane induces TNF-alpha production and facilitates TNF-alpha dependent tumoricidal responses. It also appears that the transduction of the signal, in part, at least utilizes the phosphatidyl inositol pathway. Finally, it is noteworthy that m phi activity is influenced by the sequence in which GSIB4 is presented to the m phi relative to the IFN/LPS treatment. 相似文献
8.
AB Kane RP Stanton EG Raymond ME Dobson ME Knafelc JL Farber 《The Journal of cell biology》1980,87(3):643-651
The relationship between intracellular lysosomal rupture and cell death caused by silica was studied in P388d(1) macrophages. After 3 h of exposure to 150 μg silica in medium containing 1.8 mM Ca(2+), 60 percent of the cells were unable to exclude trypan blue. In the absence of extracellular Ca(2+), however, all of the cells remained viable. Phagocytosis of silica particles occurred to the same extent in the presence or absence of Ca(2+). The percentage of P388D(1) cells killed by silica depended on the dose and the concentration of Ca(2+) in the medium. Intracellular lyosomal rupture after exposure to silica was measured by acridine orange fluorescence or histochemical assay of horseradish peroxidase. With either assay, 60 percent of the cells exposed to 150 μg silica for 3 h in the presence of Ca(2+) showed intracellular lysosomal rupture, was not associated with measureable degradation of total DNA, RNA, protein, or phospholipids or accelerated turnover of exogenous horseradish peroxidase. Pretreatment with promethazine (20 μg/ml) protected 80 percent of P388D(1) macrophages against silica toxicity although lysosomal rupture occurred in 60-70 percent of the cells. Intracellular lysosomal rupture was prevented in 80 percent of the cells by pretreatment with indomethacin (5 x 10(-5)M), yet 40-50 percent of the cells died after 3 h of exposure to 150 μg silica in 1.8 mM extracellular Ca(2+). The calcium ionophore A23187 also caused intracellular lysosomal rupture in 90-98 percent of the cells treated for 1 h in either the presence or absence of extracellular Ca(2+). With the addition of 1.8 mM Ca(2+), 80 percent of the cells was killed after 3 h, whereas all of the cells remained viable in the absence of Ca(2+). These experiments suggest that intracellular lysosomal rupture is not causally related to the cell death cause by silica or . Cell death is dependent on extracellular Ca(2+) and may be mediated by an influx of these ions across the plasma membrane permeability barrier damaged directly by exposure to these toxins. A23187相似文献
9.
10.
Wouter de Munter Arjen B Blom Monique M Helsen Birgitte Walgreen Peter M van der Kraan Leo AB Joosten Wim B van den Berg Peter LEM van Lent 《Arthritis research & therapy》2013,15(6):R178