全文获取类型
收费全文 | 422篇 |
免费 | 60篇 |
国内免费 | 1篇 |
专业分类
483篇 |
出版年
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 7篇 |
2017年 | 3篇 |
2016年 | 8篇 |
2015年 | 20篇 |
2014年 | 10篇 |
2013年 | 12篇 |
2012年 | 27篇 |
2011年 | 27篇 |
2010年 | 32篇 |
2009年 | 21篇 |
2008年 | 22篇 |
2007年 | 21篇 |
2006年 | 14篇 |
2005年 | 15篇 |
2004年 | 13篇 |
2003年 | 20篇 |
2002年 | 14篇 |
2001年 | 8篇 |
2000年 | 9篇 |
1999年 | 24篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 12篇 |
1990年 | 5篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1969年 | 2篇 |
1967年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有483条查询结果,搜索用时 15 毫秒
41.
Shun-Yao Ko Hshin-An Ko Kuo-Hsiung Chu Tzong-Ming Shieh Tzong-Cherng Chi Hong-I Chen Weng-Cheng Chang Shu-Shing Chang 《PloS one》2015,10(11)
Amyloid precursor protein (APP) has been modified by β and γ-secretase that cause amyloid deposits (plaques) in neuronal cells. Glyceraldhyde-derived AGEs has been identified as a major source of neurotoxicity in Alzheimer’s disease (AD). In a previous study, we demonstrated that glyceraldehyde-derived AGEs increase APP and Aβ via ROS. Furthermore, the combination of AGEs and Aβ has been shown to enhance neurotoxicity. In mice, APP expression is increased by tail vein injection of AGEs. This evidence suggests a correlation between AGEs and the development of AD. However, the role played by AGEs in the pathogenesis of AD remains unclear. In this report, we demonstrate that AGEs up-regulate APP processing protein (BACE and PS1) and Sirt1 expression via ROS, but do not affect the expression of downstream antioxidant genes HO-1 and NQO-1. Moreover, we found that AGEs increase GRP78 expression and enhance the cell death-related pathway p53, bcl-2/bax ratio, caspase 3. These results indicate that AGEs impair the neuroprotective effects of Sirt1 and lead to neuronal cell death via ER stress. Our findings suggest that AGEs increase ROS production, which stimulates downstream pathways related to APP processing, Aβ production, Sirt1, and GRP78, resulting in the up-regulation of cell death related pathway. This in-turn enhances neuronal cell death, which leads to the development of AD. 相似文献
42.
Shu‐Jyuan Yang Szu‐Min Chang Kun‐Che Tsai Wen‐Shiang Chen Feng‐Huei Lin Ming‐Jium Shieh 《The journal of gene medicine》2010,12(2):168-179
Background
Gene therapy has been used to treat a variety of health problems, but transfection inefficiency and the lack of safe vectors have limited clinical progress. Fabrication of a vector that is safe and has high transfection efficiency is crucial for the development of successful gene therapy. The present study aimed to synthesize chitosan‐alginate nanoparticles that can be used as carriers of the pAcGFP1‐C1 plasmid and to use these nanoparticles with an ultrasound protocol to achieve high efficiency gene transfection.Methods
Chitosan was complexed with alginate and the pAcGFP1‐C1 plasmid at different charge ratios to create chitosan‐alginate‐DNA nanoparticles (CADNs). The average particle size and loading efficiency were measured. Plasmid DNA retardation and integrity were analysed on 1% agarose gels. The effect of CADNs and ultrasound on the efficiency of transfection of cells and subcutaneous tumors was evaluated.Results
In the CADNs, the average size of incorporated plasmid DNA was 600–650 nm and the loading efficiency was greater than 90%. On the basis of the results of the plasmid DNA protection test, CADNs could protect the transgene from DNase I degradation. The transgene product expression could be enhanced efficiently if cells or tumor tissues were first given CADNs and then treated with ultrasound.Conclusions
The use of CADNs combined with an ultrasound regimen is a promising method for safe and effective gene therapy. Copyright © 2009 John Wiley & Sons, Ltd.43.
Tzu-Ling Tseng Ting Jian Hsiao-Fang Sunny Sun Jia-Ching Shieh 《Biochemical and biophysical research communications》2010,395(1):152-157
Candida albicans CDC4 is nonessential and plays a role in suppressing filamentous growth, in contrast to its evolutionary counterparts involved in the G1-S transition of the cell cycle. Genetic epistasis analysis has indicated that proteins besides Sol1 are targets of C. albicans Cdc4. Moreover, no formal evidence suggests that C. albicans Cdc4 functions through the ubiquitin E3 ligase of the Skp1-Cul1/Cdc53-F-box complex. To elucidate the role of C. albicans CDC4, C. albicans Cdc4-associated proteins were sought by affinity purification. A 6×His epitope-tagged C. albicans Cdc4 expressed from Escherichia coli was used in affinity purifications with the cell lysate of C. albicans cdc4 homozygous null mutant. Candida albicans Cdc4 and its associated proteins were resolved by SDS-PAGE and visualized by silver staining. The candidate proteins were recovered and trypsin-digested to generate MALDI-TOF spectra profiles, which were used to search against those of known proteins in the database to reveal their identities. Two out of four proteins encoded by GPH1 and THR1 genes were further verified to interact with C. albicans Cdc4 using a yeast two-hybrid assay. We conclude that in vitro affinity purification using C. albicans Cdc4 generated from E. coli as the bait and proteins from cell lysate of C. albicans cdc4 homozygous null mutant as a source of prey permit the identification of novel proteins that physically interact and functionally associate with C. albicans Cdc4. 相似文献
44.
45.
Peter L. Irwin Michael D. Sevilla James J. Shieh 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1984,805(2):186-190
Electron spin resonance linewidth measurements have been made on intact cell walls exchanged with various combinations of Mn2+ and Ca2+. These experiments were performed to find the Mn2+ nearest-neighbor distance and thereby determine whether carboxylate-Mn2+ complexes potentiate ion association at adjacent sites on cell wall polyuronides. Our results show that as the fraction of available binding sites occupied by Mn2+ increased from 2% to 27%, the nearest-neighbor distance parameter decreased only from 14 to 11 Å. These distances are close to polyuronide interanionic spacings. The small change in the distance parameter with concentration is evidence for sequential rather than random binding. Competitive ion-exchange with Ca2+ was found to reduce the Mn2+ spin-spin line broadening at similar total bound Mn2+ concentrations. This is expected only if Ca2+ competes at adjacent sites. The data presented offer strong support for the hypothesis that carboxylate groups near already occupied sites have a greater affinity for divalent cations than other sites along the polyuronide main chain. 相似文献
46.
47.
An E224G mutation of the Kir2.1 channel generates intrinsic inward rectification and single-channel fluctuations in the absence
of intracellular blockers. In this study, we showed that positively charged residues H226, R228 and R260, near site 224, regulated
the intrinsic inward rectification and single-channel properties of the E224G mutant. By carrying out systematic mutations,
we found that the charge effect on the intrinsic inward rectification and single-channel conductance is consistent with a
long-range electrostatic mechanism. A Kir1.1 channel where the site equivalent to E224 in the Kir2.1 channel is a glycine
residue does not show inward rectification or single-channel fluctuations. The G223K and N259R mutations of the Kir1.1 channel
induced intrinsic inward rectification and reduced the single-channel conductance but did not generate large open-channel
fluctuations. Substituting the cytoplasmic pore of the E224G mutant into the Kir1.1 channel induced open-channel fluctuations
and intrinsic inward rectification. The single-channel conductance of the E224G mutant showed inward rectification. Also,
a voltage-dependent gating mechanism decreased open probability during depolarization and contributed to the intrinsic inward
rectification in the E224G mutant. In addition to an electrostatic effect, a close interaction of K+ with channel pore may be required for generating open-channel fluctuations in the E224G mutant. 相似文献
48.
49.
Ching-Hung Tseng Pei-Wen Chiang Hung-Chun Lai Fuh-Kwo Shiah Ting-Chang Hsu Yi-Lung Chen Liang-Saw Wen Chun-Mao Tseng Wung-Yang Shieh Isaam Saeed Saman Halgamuge Sen-Lin Tang 《BMC genomics》2015,16(1)
Background
Prokaryotic microbes, the most abundant organisms in the ocean, are remarkably diverse. Despite numerous studies of marine prokaryotes, the zonation of their communities in pelagic zones has been poorly delineated. By exploiting the persistent stratification of the South China Sea (SCS), we performed a 2-year, large spatial scale (10, 100, 1000, and 3000 m) survey, which included a pilot study in 2006 and comprehensive sampling in 2007, to investigate the biological zonation of bacteria and archaea using 16S rRNA tag and shotgun metagenome sequencing.Results
Alphaproteobacteria dominated the bacterial community in the surface SCS, where the abundance of Betaproteobacteria was seemingly associated with climatic activity. Gammaproteobacteria thrived in the deep SCS, where a noticeable amount of Cyanobacteria were also detected. Marine Groups II and III Euryarchaeota were predominant in the archaeal communities in the surface and deep SCS, respectively. Bacterial diversity was higher than archaeal diversity at all sampling depths in the SCS, and peaked at mid-depths, agreeing with the diversity pattern found in global water columns. Metagenomic analysis not only showed differential %GC values and genome sizes between the surface and deep SCS, but also demonstrated depth-dependent metabolic potentials, such as cobalamin biosynthesis at 10 m, osmoregulation at 100 m, signal transduction at 1000 m, and plasmid and phage replication at 3000 m. When compared with other oceans, urease at 10 m and both exonuclease and permease at 3000 m were more abundant in the SCS. Finally, enriched genes associated with nutrient assimilation in the sea surface and transposase in the deep-sea metagenomes exemplified the functional zonation in global oceans.Conclusions
Prokaryotic communities in the SCS stratified with depth, with maximal bacterial diversity at mid-depth, in accordance with global water columns. The SCS had functional zonation among depths and endemically enriched metabolic potentials at the study site, in contrast to other oceans.Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1434-3) contains supplementary material, which is available to authorized users. 相似文献50.