全文获取类型
收费全文 | 194篇 |
免费 | 19篇 |
国内免费 | 14篇 |
专业分类
227篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 12篇 |
2021年 | 7篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 13篇 |
2014年 | 7篇 |
2013年 | 22篇 |
2012年 | 19篇 |
2011年 | 10篇 |
2010年 | 6篇 |
2009年 | 15篇 |
2008年 | 12篇 |
2007年 | 19篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1977年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有227条查询结果,搜索用时 0 毫秒
1.
2.
3.
江西井冈山地区灰胸竹鸡的遗传多样性研究 总被引:1,自引:0,他引:1
灰胸竹鸡Bambusicola thoracica是我国特有鸟类.本文采用聚合链式反应和直接测序的方法测定井冈山地区灰胸竹鸡3个种群线粒体DNA(mtDNA)控制区1142 bp的序列,分析其序列变异和种群遗传多样性.30个样本共发现16个变异位点和10种单倍型,其中hapl广泛分布,占所分析样本的23.33%,是其祖先单倍型.3个种群的平均单倍型多样性和核苷酸多样性分别为0.815和0.00243.青原区种群与其它两个种群遗传分化显著,基因交流受限制.受隔离影响,青原区种群遗传多样性最低.在系统发生树上,10种单倍型形成两支,井冈山种群和永新县种群聚在一起,与其地理位置相一致. 相似文献
4.
Planktonic members of most algal groups are known to harbor intracellular symbionts, including viruses, bacteria, fungi, and protozoa. Among the dinoflagellates, viral and bacterial associations were recognized a quarter century ago, yet their impact on host populations remains largely unresolved. By contrast, fungal and protozoan infections of dinoflagellates are well documented and generally viewed as playing major roles in host population dynamics. Our understanding of fungal parasites is largely based on studies for freshwater diatoms and dinoflagellates, although fungal infections are known for some marine phytoplankton. In freshwater systems, fungal chytrids have been linked to mass mortalities of host organisms, suppression or retardation of phytoplankton blooms, and selective effects on species composition leading to successional changes in plankton communities. Parasitic dinoflagellates of the genus Amoebophrya and the newly described Perkinsozoa, Parvilucifera infectans, are widely distributed in coastal waters of the world where they commonly infect photosynthetic and heterotrophic dinoflagellates. Recent work indicates that these parasites can have significant impacts on host physiology, behavior, and bloom dynamics. Thus, parasitism needs to be carefully considered in developing concepts about plankton dynamics and the flow of material in marine food webs. 相似文献
5.
Low-glutamine fed-batch cultures of 293-HEK serum-free suspension cells for adenovirus production 总被引:1,自引:0,他引:1
Recent developments in gene therapy using adenoviral (Ad) vectors have fueled renewed interest in the 293 human embryonic kidney cell line traditionally used to produce these vectors. Low-glutamine fed-batch cultures of serum-free, suspension cells in a 5-L bioreactor were conducted. Our aim was to tighten the control on glutamine metabolism and hence reduce ammonia and lactate accumulation. Online direct measurement of glutamine was effected via a continuous cell-exclusion system that allows for aseptic, cell-free sampling of the culture broth. A feedback control algorithm was used to maintain the glutamine concentration at a level as low as 0.1 mM with a concentrated glucose-free feed medium. This was tested in two media: a commercial formulation (SFM II) and a chemically defined DMEM/F12 formulation. The fed-batch and batch cultures were started at the same glucose concentration, and it was not controlled at any point in the fed-batch cultures. In all cases, fed-batch cultures with double the cell density and extended viable culture time compared to the batch cultures were achieved. An infection study on the high density fed-batch culture using adenovirus-green fluorescent protein (Ad-GFP) construct was also done to ascertain the production capacity of the culture. Virus titers from the infected fed-batch culture showed that there is an approximately 10-fold improvement over a batch infection culture. The results have shown that the control of glutamine at low levels in cultures is sufficient to yield significant improvements in both cell densities and viral production. The applicability of this fed-batch system to cultures in different media and also infected cultures suggests its potential for application to generic mammalian cell cultures. 相似文献
6.
7.
Organisms used as model genomics systems are maintained as isogenic strains, yet evidence of sequence differences between independently maintained wild-type stocks has been substantiated by whole-genome resequencing data and strain-specific phenotypes. Sequence differences may arise from replication errors, transposon mobilization, meiotic gene conversion, or environmental or chemical assault on the genome. Low frequency alleles or mutations with modest effects on phenotypes can contribute to natural variation, and it has proven possible for such sequences to become fixed by adapted evolutionary enrichment and identified by resequencing. Our objective was to identify and analyze single locus genetic defects leading to RNAi resistance in isogenic strains of Caenorhabditis elegans. In so doing, we uncovered a mutation that arose de novo in an existing strain, which initially frustrated our phenotypic analysis. We also report experimental, environmental, and genetic conditions that can complicate phenotypic analysis of RNAi pathway defects. These observations highlight the potential for unanticipated mutations, coupled with genetic and environmental phenomena, to enhance or suppress the effects of known mutations and cause variation between wild-type strains. 相似文献
8.
9.
Dey Chyi Sheu Jan Yi Chang Chung Yih Wang Chang Ta Wu Chen Ji Huang 《Bioprocess and biosystems engineering》2013,36(11):1745-1751
High-purity fructooligosaccharides (FOS) were produced from sucrose by an innovative process incorporating immobilized Aspergillus japonicus and Pichia heimii cells. Intracellular FTase of A. japonicus converted sucrose into FOS and glucose, and P. heimii fermented glucose mainly into ethanol. The continuous production of FOS was carried out using a tanks-in-series bioreactor consisting of three stirred tanks. When a solution composed of 1 g L?1 yeast extract and 300 g L?1 sucrose was fed continuously to the bioreactor at a dilution rate of 0.1 h?1, FOS at a purity of up to 98.2 % could be achieved and the value-added byproduct ethanol at 79.6 g L?1 was also obtained. One gram of sucrose yielded 0.62 g FOS and 0.27 g ethanol. This immobilized dual-cell system was effective for continuous production of high-purity FOS and ethanol for as long as 10 days. 相似文献
10.
Chemiluminescence analysis of antioxidant capacity for serum albumin isolated from healthy or uremic volunteers
下载免费PDF全文
![点击此处可从《Luminescence》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Chih‐Yang Huang Show‐Yih Liou Wei‐Wen Kuo Hsi‐Chin Wu Yen‐Lin Chang Tung‐Sheng Chen 《Luminescence》2016,31(8):1474-1478
Regular hemodialysis treatment induces an elevation in oxidative stress in patients with end‐stage renal failure, resulting in oxidative damage of the most abundant serum protein, albumin. Oxidation of serum albumin causes depletion of albumin reactive thiols, leading to oxidative modification of serum albumin. The aim of this study was to screen the antioxidant capacity of albumins isolated from uremic patients (HD‐ALB) or healthy volunteers (N‐ALB). From high‐performance liquid chromatography spectra, we observed that one uremic solute binds to HD‐ALB via the formation of disulfide bonds between HD‐ALB and the uremic solute. Furthermore, we found using chemiluminescent analysis that the antioxidant capacities for N‐ALB to scavenge reactive oxygen species including singlet oxygen, hypochlorite and hydrogen peroxide were higher than HD‐ALB. Our results suggest that protein‐bound uremic solute binds to albumin via formation of disulfide bonds, resulting in the depletion of albumin reactive thiols. The depletion of albumin reactive thiols leads to a reduced antioxidant capacity of HD‐ALB, implying postmodification of albumin. This situation may reduce the antioxidant capacity of albumin and increase oxidative stress, resulting in increase in complications related to oxidative damage in uremic patients. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献