全文获取类型
收费全文 | 1200篇 |
免费 | 76篇 |
专业分类
1276篇 |
出版年
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 22篇 |
2020年 | 15篇 |
2019年 | 24篇 |
2018年 | 19篇 |
2017年 | 26篇 |
2016年 | 47篇 |
2015年 | 63篇 |
2014年 | 57篇 |
2013年 | 58篇 |
2012年 | 108篇 |
2011年 | 95篇 |
2010年 | 52篇 |
2009年 | 58篇 |
2008年 | 91篇 |
2007年 | 59篇 |
2006年 | 59篇 |
2005年 | 76篇 |
2004年 | 60篇 |
2003年 | 50篇 |
2002年 | 52篇 |
2001年 | 27篇 |
2000年 | 28篇 |
1999年 | 27篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有1276条查询结果,搜索用时 0 毫秒
81.
Chae Young-Am Hee-Suk Yu Ji-Sook Song Hee-Kyung Chun Sang-Un Park 《Biotechnology letters》2000,22(19):1527-1530
The transformed root culture of Polygonum tinctorium Lour. was established by infecting leaf explants with Agrobacterium rhizogenes A4. These cultures were examined for their growth and indigo content under various culture conditions. Among the four different culture media tested, SH medium showed the highest yield for root growth (28 mg dry wt/30 ml) and indigo production (152 g/dry wt). In SH medium, 30 g sucrose l–1, 2500 mg KNO3 l–1, 300 mg NH4H2PO4 l–1 were the best conditions for indigo production at pH 5.7. The production of indigo in hairy roots slightly increased with the addition of 200 mg chitosan l–1 (186 g/dry wt) and 20 U pectinase l–1 (181 g/dry wt). 相似文献
82.
Jang HH Kim SY Park SK Jeon HS Lee YM Jung JH Lee SY Chae HB Jung YJ Lee KO Lim CO Chung WS Bahk JD Yun DJ Cho MJ Lee SY 《FEBS letters》2006,580(1):351-355
The H2O2-catabolizing peroxidase activity of human peroxiredoxin I (hPrxI) was previously shown to be regulated by phosphorylation of Thr90. Here, we show that hPrxI forms multiple oligomers with distinct secondary structures. HPrxI is a dual function protein, since it can behave either as a peroxidase or as a molecular chaperone. The effects of phosphorylation of hPrxI on its protein structure and dual functions were determined using site-directed mutagenesis, in which the phosphorylation site was substituted with aspartate to mimic the phosphorylated status of the protein (T90D-hPrxI). Phosphorylation of the protein induces significant changes in its protein structure from low molecular weight (MW) protein species to high MW protein complexes as well as its dual functions. In contrast to the wild type (WT)- and T90A-hPrxI, the T90D-hPrxI exhibited a markedly reduced peroxidase activity, but showed about sixfold higher chaperone activity than WT-hPrxI. 相似文献
83.
Cellular differentiation-induced attenuation of LPS response in HT-29 cells is related to the down-regulation of TLR4 expression 总被引:3,自引:0,他引:3
Lee SK Il Kim T Kim YK Choi CH Yang KM Chae B Kim WH 《Biochemical and biophysical research communications》2005,337(2):457-463
Intestinal epithelial cells not only present a physical barrier to bacteria but also participate actively in immune and inflammatory responses. The migration of epithelial cells from the crypt base to the surface is accompanied by a cellular differentiation that leads to important morphological and functional changes. It has been reported that the differentiation of colonic epithelial cells is associated with reduced interleukin (IL)-8 responses to IL-1beta. Although toll-like receptor 4 (TLR4) has been previously identified to be an important component of mucosal immunity to lipopolysaccharide (LPS) in the colon, little is known about the regulation of TLR4 in colonic epithelial cells during cellular differentiation. We investigated the effects of differentiation on LPS-induced IL-8 secretion and on the expression of TLR4. Differentiation was induced in colon cancer cell line HT-29 cells by butyrate treatment or by post-confluence culture and assessed by measuring alkaline phosphatase (AP) activity. IL-8 secretion was measured by ELISA, and TLR4 protein and mRNA expressions were followed by Western blot and RT-PCR, respectively. HT-29 cells were found to be dose-dependently responsive to LPS. AP activity increased in HT-29 cells by differentiation induced by treatment with butyrate or post-confluence culture. We found that IL-8 secretion induced by LPS was strongly attenuated in differentiated cells versus undifferentiated cells, and that cellular differentiation also attenuated TLR4 mRNA and protein expressions. Pretreating HT-29 cells with tumor necrosis factor (TNF)-alpha or interferon (INF)-gamma augmented LPS-induced IL-8 secretion and TLR4 expression. These TNF-alpha- or INF-gamma-induced augmentations of LPS response and TLR4 expression were all down-regulated by differentiation. Collectively, we conclude that cellular differentiation attenuates IL-8 secretion induced by LPS in HT-29 cells, and this attenuation is related with the down-regulation of TLR4 expression. 相似文献
84.
The ATPase activity of the plasma membrane-enriched fractionwas severely inhibited by withdrawal of Ca2+ from the mediumfor 5 days, although the root system appeared to be unaffectedto visual inspection. Partially lipid-depleted ATPases withsimilar ratios of phospholipid to protein were prepared fromthe plasma membrane-enriched fraction of cucumber roots culturedwith control medium and one lacking Ca2+, and their propertieswere compared. SDS disc polyacrylamide gel electrophoresis showedthat the polypeptide components were essentially similar betweencontrol and Ca2+-starved roots. Partially lipid-depleted ATPasereassociated with asolectin, the lecithin from soybean, showedtypical characteristics of plasma membrane type ATPase; pH optimumat 6.5, high specificity for ATP as substrate and strong inhibitionby vanadate but not nitrate. The activity of reassociated ATPaseobtained from the control roots was apparently higher than theactivity obtained from Ca2+-starved roots. The amount of asolectinrequired for maximum activation of the partially lipid-depletedATPase prepared from control roots was much lower than thatprepared from Ca2+-starved roots. Reassociation of partiallylipid-depleted ATPase with asolectin produced higher ATPaseactivity than that with individual phospholipids. The activationof partially lipid-depleted ATPase prepared from control rootswith asolectin was not inhibited by addition of a sample preparedfrom Ca2+-starved roots. Thus, a decrease in the functionalassociation of ATPase with phospholipids might be one of thephysiological injuries in root cell membranes of cucumber causedby Ca2+ starvation.
1Permanent address: Department of Horticulture, College of Agriculture,Chonnam National University, Chonnam 500, Korea. (Received February 23, 1988; Accepted August 18, 1988) 相似文献
85.
Lee JunHyung Hosseindoust Abdolreza Kim MinJu Kim KwangYeol Choi YoHan Lee SeokHee Lee SongYi Cho HyunJong Kang Wei Soo Chae ByungJo 《Biological trace element research》2020,193(2):536-547
Biological Trace Element Research - In this study, the pattern of metals concentration in water, sediment, plants, and three edible fish species (Channa striata, Labeo rohita, and Catla catla) of... 相似文献
86.
Justin M. Gifford Won Byoung Chae Kankshita Swaminathan Stephen P. Moose John A. Juvik 《Global Change Biology Bioenergy》2015,7(4):797-810
In light of rising energy costs, lignocellulosic ethanol has been identified as a renewable alternative to petroleum-based transportation fuels. In an attempt to reach government mandated ethanol production levels, potential plant biofeedstock candidates have been investigated, and cold-tolerant, perennial accessions within the C4 grass genus Miscanthus have been identified as leading contenders in the Midwestern US. To facilitate the development of improved cultivars through marker-assisted breeding, a quantitative trait locus (QTL) study was conducted on a full-sib, F1 mapping population segregating for flowering time, height, leaf width, and yield using a genetic map consisting of 846 segregating SNP and SSR markers. This was a 3 year study investigating the genetic architecture underlying traits important to biomass production in a population of 221 progeny from a cross between M. sinensis ‘Grosse Fountaine’ and M. sinensis ‘Undine’ established in the spring of 2010; 72 QTLs with LOD scores above the genome-wide, permuted threshold equivalent to a P-value of 0.05 were identified across 13 traits. Of the 36 QTLs identified in 2011, 22 were detected again the following year. Both the use of spring emergence and vigor rating as a covariate to account for variation related to differences in establishment increased the power to detect QTLs in the 2 year establishment period. Finally, a dry period in the middle of the 2012 growing season suggested that yield declines were due to a decrease in tiller diameter. 相似文献
87.
Expression of viral microRNAs in Epstein-Barr virus-associated gastric carcinoma 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Kim do N Chae HS Oh ST Kang JH Park CH Park WS Takada K Lee JM Lee WK Lee SK 《Journal of virology》2007,81(2):1033-1036
Epstein-Barr virus (EBV) is associated with about 6 to 16% of gastric carcinoma cases worldwide. Expression of the EBV microRNAs (miRNAs) was observed in B cells and nasopharyngeal carcinoma cells infected with EBV. However, it is not clear if the EBV miRNAs are expressed in EBV-associated gastric carcinomas (EBVaGCs). We found that BART miRNAs but not BHRF1 miRNAs were expressed in EBV-infected gastric carcinoma cell lines and the tumor tissues from patients as well as the animal model. The expression of viral miRNAs in EBVaGCs suggests that these EBV miRNAs may play important roles in the tumorigenesis of EBVaGCs. 相似文献
88.
89.
Kim SY Park JS Chae CS Hyun CG Choi BW Shin J Oh KB 《Applied microbiology and biotechnology》2007,75(5):1119-1126
Indolocarbazole metabolite K-252a is a natural product that was previously reported as a potent protein kinase C inhibitor
with in vitro and in vivo potency. From a biosynthetic viewpoint, this compound possesses structurally interesting features
such as an unusual furanosyl sugar moiety, which are absent in the well-studied staurosporine and rebeccamycin. A cosmid library
from genomic DNA of Nonomuraea longicatena JCM 11136 was constructed and screened for the presence of genes to be involved in the biosynthesis of indolocarbazole K-252a.
Using as a probe an internal fragment of vioB, a Chromobacterium violaceum gene encoding a multifunctional enzyme that catalyzes tryptophan decarboxylation and condensation reaction in violacein biosynthesis,
we isolated a DNA region that directed the biosynthesis of K-252a when introduced into the heterologous expression host Streptomyces albus. Sequence analysis of 45 kb revealed genes for indolocarbazole core formation, glycosylation, and sugar methylation, as well
as a regulatory gene and two resistance/secretion genes. The cloned genes should help to elucidate the molecular basis for
indolocarbazole biosynthesis and generate new indolocarbazole analogues by genetic engineering. 相似文献
90.