全文获取类型
收费全文 | 362篇 |
免费 | 15篇 |
国内免费 | 3篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 16篇 |
2020年 | 12篇 |
2019年 | 12篇 |
2018年 | 21篇 |
2017年 | 8篇 |
2016年 | 22篇 |
2015年 | 26篇 |
2014年 | 29篇 |
2013年 | 37篇 |
2012年 | 43篇 |
2011年 | 21篇 |
2010年 | 17篇 |
2009年 | 15篇 |
2008年 | 21篇 |
2007年 | 24篇 |
2006年 | 16篇 |
2005年 | 11篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 2篇 |
1994年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有380条查询结果,搜索用时 109 毫秒
71.
Deepak?Kumar Vinod?K.?Kannaujiya Richa Jainendra?Pathak Shanthy?Sundaram Rajeshwar?P.?SinhaEmail authorView authors OrcID profile
return OK on get 《Protoplasma》2018,255(3):885-898
Circadian rhythm is an important endogenous biological signal for sustainable growth and development of cyanobacteria in natural ecosystems. Circadian effects of photosynthetically active radiation (PAR), ultraviolet-A (UV-A) and ultraviolet-B (UV-B) radiations on pigment composition have been studied in the cyanobacterium Spirulina platensis under light (L)/dark (D) oscillation with a combination of 4/20, 8/16, 12/12, 16/8, 20/4 and 24/24 h time duration. Circadian exposure of PAR?+?UV-A (PA) and PAR?+?UV-A?+?UV-B (PAB) showed more than twofold decline in Chl a, total protein and phycocyanin (PC) in light phase and significant recovery was achieved in dark phase. The fluorescence emission wavelength of PC was shifted towards lower wavelengths in the light phase of PAB in comparison to P and PA whereas the same wavelength was retrieved in the dark phase. The production of free radicals was accelerated twofold in the light phase (24 h L) whereas the same was retrieved to the level of control during the dark phase. Oxidatively induced damage was alleviated by antioxidative enzymes such as catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and ascorbate peroxidase (APX) in the light phase (0–24-h L) whereas the dark phase showed significant inhibition of the same enzymes. Similar characteristic inhibition of free radicals and recovery of PC was observed inside cellular filament after circadian rhythm of 24/24 h (L/D). Circadian exposure of P, PA and PAB significantly altered the synthesis and recovery of pigments that could be crucial for optimization and sustainable production of photosynthetic products for human welfare. 相似文献
72.
S. R. Chandramouli Karthikeyan Vasudevan S. Harikrishnan Sushil Kumar Dutta S. Jegath Janani Richa Sharma Indraneil Das Ramesh K. Aggarwal 《ZooKeys》2016,(555):57-90
A new bufonid amphibian, belonging to a new monotypic genus, is described from the Andaman Islands, in the Bay of Bengal, Republic of India, based on unique external morphological and skeletal characters which are compared with those of known Oriental and other relevant bufonid genera. Blythophryne
gen. n. is distinguished from other bufonid genera by its small adult size (mean SVL 24.02 mm), the presence of six presacral vertebrae, an absence of coccygeal expansions, presence of an elongated pair of parotoid glands, expanded discs at digit tips and phytotelmonous tadpoles that lack oral denticles. The taxonomic and phylogenetic position of the new taxon (that we named as Blythophryne
beryet
gen. et sp. n.) was ascertained by comparing its 12S and 16S partial genes with those of Oriental and other relevant bufonid lineages. Resulting molecular phylogeny supports the erection of a novel monotypic genus for this lineage from the Andaman Islands of India. 相似文献
73.
74.
Gururaj Shivange Mohan Monisha Richa Nigam Naveena Kodipelli Roy Anindya 《Nucleic acids research》2016,44(18):8754-8763
The Escherichia coli AlkB protein is a 2-oxoglutarate/Fe(II)-dependent demethylase that repairs alkylated single stranded and double stranded DNA. Immunoaffinity chromatography coupled with mass spectrometry identified RecA, a key factor in homologous recombination, as an AlkB-associated protein. The interaction between AlkB and RecA was validated by yeast two-hybrid assay; size-exclusion chromatography and standard pull down experiment and was shown to be direct and mediated by the N-terminal domain of RecA. RecA binding results AlkB–RecA heterodimer formation and RecA–AlkB repairs alkylated DNA with higher efficiency than AlkB alone. 相似文献
75.
76.
Irina?Maljkovic BerryEmail author Melanie?C.?Melendrez Tao?Li Anthony?W.?Hawksworth Gary?T.?Brice Patrick?J.?Blair Eric?S.?Halsey Maya?Williams Stefan?Fernandez In-Kyu?Yoon Leslie?D.?Edwards Robert?Kuschner Xiaoxu?Lin Stephen?J.?Thomas Richard?G.?Jarman 《BMC biology》2016,14(1):117
Background
Increasing evidence suggests that influenza reassortment not only contributes to the emergence of new human pandemics but also plays an important role in seasonal influenza epidemics, disease severity, evolution, and vaccine efficacy. We studied this process within 2091 H3N2 full genomes utilizing a combination of the latest reassortment detection tools and more conventional phylogenetic analyses.Results
We found that the amount of H3N2 intra-subtype reassortment depended on the number of sampled genomes, occurred with a steady frequency of 3.35%, and was not affected by the geographical origins, evolutionary patterns, or previous reassortment history of the virus. We identified both single reassortant genomes and reassortant clades, each clade representing one reassortment event followed by successful spread of the reassorted variant in the human population. It was this spread that was mainly responsible for the observed high presence of H3N2 intra-subtype reassortant genomes. The successfully spread variants were generally sampled within one year of their formation, highlighting the risk of their rapid spread but also presenting an opportunity for their rapid detection. Simultaneous spread of several different reassortant lineages was observed, and despite their limited average lifetime, second and third generation reassortment was detected, as well as reassortment between viruses belonging to different vaccine-associated clades, likely displaying differing antigenic properties. Some of the spreading reassortants remained confined to certain geographical regions, while others, sharing common properties in amino acid positions of the HA, NA, and PB2 segments, were found throughout the world.Conclusions
Detailed surveillance of seasonal influenza reassortment patterns and variant properties may provide unique information needed for prediction of spread and construction of future influenza vaccines.77.
Why only a subpopulation (about 15%) of humans develops liver cirrhosis due to alcohol is a critical as yet unanswered question. Liver-specific depletion of augmenter of liver regeneration (ALR) protein in mice causes robust steatosis and hepatocyte apoptosis by 2 weeks; these pathologies regress subsequently with return of ALR expression even at lower than control levels, but the mice develop modest steatohepatitis by 8 weeks. We aimed to investigate whether chronic alcohol ingestion promotes excessive hepatic fibrosis in these ALR-deficient mice. Liver-specific ALR-deficient and wild type (WT) female mice (8–10 weeks old) were placed on 4% alcohol-supplemented or isocaloric diet for 4 weeks. Liver sections were examined for histopathology, and parameters of steatosis and fibrosis were quantified. The mRNA expression of alcohol dehydrogenase-1, acetaldehyde dehydrogenase-1 and cytochrome P450-2E1 increased in WT mice but decreased in ALR-deficient mice upon alcohol ingestion. While alcohol induced steatosis and mild inflammation in WT mice, ALR-deficient mice showed minimal steatosis, strong hepatocellular injury and inflammation, prominent ductular proliferation, and robust fibrosis. Compared to the WT mice, alcohol feeding of ALR-deficient mice resulted in significantly greater increase in hepatic TNFα and TGFβ, and oxidative stress; there was also hepatic iron accumulation, robust lipid peroxidation and mitochondrial DNA damage. Importantly, similar to ALR-deficient mice, lower hepatic ALR levels in human alcoholic liver cirrhosis were associated with increased iron content, reduced expression of alcohol dehydrogenase and acetaldehyde dehydrogenase, and elevated fibrogenic markers. We conclude that ALR deficiency or anomaly can play a critical role in alcohol-induced hepatic fibrosis/cirrhosis, mechanisms of which may involve dysregulation of alcohol metabolism and iron homeostasis, mitochondrial damage and oxidative injury. 相似文献
78.
79.
Plasmonics - In the present work, an investigation of wavelength-dependent absorption spectrum of spherical nanoparticles with different arrangements in organic medium using discrete dipole... 相似文献
80.