全文获取类型
收费全文 | 511篇 |
免费 | 39篇 |
专业分类
550篇 |
出版年
2024年 | 2篇 |
2023年 | 8篇 |
2022年 | 22篇 |
2021年 | 32篇 |
2020年 | 28篇 |
2019年 | 52篇 |
2018年 | 33篇 |
2017年 | 23篇 |
2016年 | 36篇 |
2015年 | 34篇 |
2014年 | 36篇 |
2013年 | 49篇 |
2012年 | 41篇 |
2011年 | 36篇 |
2010年 | 24篇 |
2009年 | 21篇 |
2008年 | 8篇 |
2007年 | 15篇 |
2006年 | 14篇 |
2005年 | 8篇 |
2004年 | 12篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1991年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有550条查询结果,搜索用时 15 毫秒
101.
Nazi Nadernejad Ali Ahmadimoghadam Javad Hossyinifard Shahram Poorseyedi 《Trees - Structure and Function》2013,27(6):1681-1689
Phenylalanine ammonia-lyase (PAL) is a biochemical marker of environmental stress and plays a pivotal role in phenolic synthesis. Lower ROS levels and oxidative damage were observed in grafted plants; moreover, the rootstocks have a profound influence on the biochemical composition, especially of phenolic compounds. Regarding the importance of the effect rootstocks have on scion in pistachio trees, this study was carried out to assess and compare three pistachio cultivars (Ahmadaghaii, Ohadi and Kallehghuchi) on four rootstocks (Mutica, Ahli, Sarakhs and Atlantica). PAL activity, phenolic compounds, and flavonoid and anthocyanin contents in leaves, flowers and fruits were measured for the selection of the most suitable and compatible rootstock/scion resistant to environmental stresses. The results showed that PAL activity was different among the cultivars and organs. A positive correlation was observed between PAL activity and phenolic compounds in the leaves and flowers of Mutica-Ahmadaghaii, suggesting that it was more resistant than the others to environmental stresses. PAL activity and total phenolics in pistachio fruits suffered a decrease when the maturation processes began. The hulls of the pistachio fruits contained high levels of phenolic compounds, especially in Mutica-Ahmadaghaii, suggesting its function as a protective layer and a defense chemical against ultraviolet radiation and pathogens. Our results indicated the presence of a number of bioactive compounds in kernels with the highest amount belonging to Mutica-Ahmadaghaii. Therefore, we concluded that pistachio rootstocks mighy affect the antioxidant compounds in kernels. 相似文献
102.
103.
104.
Focal adhesions are critical to a number of cellular processes that involve mechanotransduction and mechanical interaction with the cellular environment. The growth and strengthening of these focal adhesions is dependent on the interaction between talin and vinculin. This study investigates said interaction and how vinculin activation influences it. Using molecular dynamics, the interaction between talin's vinculin binding site (VBS) and vinculin's domain 1 (D1) is simulated both before and after vinculin activation. The simulations of VBS binding to vinculin before activation suggest the proximity of the vinculin tail to D1 prevents helical movement in D1 and thus prevents binding of VBS. In contrast, interaction of VBS with activated vinculin shows the possibility of complete VBS insertion into D1. In the simulations of both activated and autoinhibited vinculin where VBS fails to fully bind, VBS demonstrates significant hydrophobic interaction with surface residues in D1. These interactions link VBS to D1 even without its proper insertion into the hydrophobic core. Together these simulations suggest VBS binds to vinculin with the following mechanism: 1), VBS links to D1 via surface hydrophobic interactions; 2), vinculin undergoes activation and D1 is moved away from the vinculin tail; 3), helices in D1 undergo conformational change to allow VBS binding; and 4), VBS inserts itself into the hydrophobic core of D1. 相似文献
105.
Tavakkoly-Bazzaz J Amiri P Tajmir-Riahi M Javidi D Khojasteh-Fard M Taheri Z Tabrizi A Keramatipour M Amoli MM 《Gene》2011,487(1):103-106
Objective
Increased RANTES expression has been described to have a role in atherosclerosis plaque formation. Functional polymorphisms within RANTES promoter region have shown association with increased risk of coronary atherosclerosis (CAD). The aim of this study was to examine the RANTES mRNA expression in patients with CAD compared to patients without CAD and its association with RANTES − 403 G/A polymorphism in an Iranian population.Methods
The study was performed on 319 patients who underwent coronary artery angiography and patients with > 50% stenosis in vessels considered as case groups (CAD+) N = 191 and normal vessels group as control (CAD−) N = 128. In each group 20 patients were examined for RANTES mRNA expression.RANTES mRNA expression was examined using quantitative real-time PCR. Genotyping of − 403 polymorphism was performed using PCR-RFLP technique.Results
We found that RANTES mRNA expression was increased to 1.37 fold in CAD patients compared to the controls but the difference was not statistically significant. Also comparing the RANTES mRNA expression in patients with different RANTES − 403 G/A polymorphism showed that in patients carrying AA genotype RANTES mRNA expression was increased to 1.74 fold compared to patients carrying GG genotype and to 1.51 fold compared to patients carrying GA genotype. No significant difference for allele and genotype frequencies of RANTES − 403 polymorphism was found between cases and controls.Conclusion
More studies on larger number of samples are required to further evaluate role of RANTES in pathogenesis of CAD. 相似文献106.
Zomorodian K Rahimi MJ Safaei A Bazargani A Motamadi M Kharazi M Mostaghni S Pakshir K Ghaedi H Afsarian MH 《Journal of microbiological methods》2011,85(3):233-234
The aim of the study was to assess the reliability of human blood agar media (HuBA) in identifying Streptococcus pyogenes by hemolysis analysis. We analyze several factors that might affect the accuracy of HuBA media for microbial analysis, including incubation time, blood group, Rh factor and presence of antistreptolysin-o. 相似文献
107.
Sherry Dadgar Zuyi Wang Helen Johnston Akanchha Kesari Kanneboyina Nagaraju Yi-Wen Chen D. Ashley Hill Terence A. Partridge Mamta Giri Robert J. Freishtat Javad Nazarian Jianhua Xuan Yue Wang Eric P. Hoffman 《The Journal of cell biology》2014,207(1):139-158
We sought to determine the mechanisms underlying failure of muscle regeneration that is observed in dystrophic muscle through hypothesis generation using muscle profiling data (human dystrophy and murine regeneration). We found that transforming growth factor β–centered networks strongly associated with pathological fibrosis and failed regeneration were also induced during normal regeneration but at distinct time points. We hypothesized that asynchronously regenerating microenvironments are an underlying driver of fibrosis and failed regeneration. We validated this hypothesis using an experimental model of focal asynchronous bouts of muscle regeneration in wild-type (WT) mice. A chronic inflammatory state and reduced mitochondrial oxidative capacity are observed in bouts separated by 4 d, whereas a chronic profibrotic state was seen in bouts separated by 10 d. Treatment of asynchronously remodeling WT muscle with either prednisone or VBP15 mitigated the molecular phenotype. Our asynchronous regeneration model for pathological fibrosis and muscle wasting in the muscular dystrophies is likely generalizable to tissue failure in chronic inflammatory states in other regenerative tissues. 相似文献
108.
Brim H Kumar K Nazarian J Hathout Y Jafarian A Lee E Green W Smoot D Park J Nouraie M Ashktorab H 《PloS one》2011,6(6):e20216
Background
Colon cancer is one of the leading causes of cancer related deaths. Its impact on African Americans (AAs) is higher than in the general population both in the incidence and mortality from the disease. Colon cancer aggressiveness in AAs as well as non-frequent check-ups and follow up in this population have been proposed as ways to explain the observed discrepancies. These facts made the detection of early carcinogenesis markers in this population a priority.Materials and Methods
Here, we analyzed 50 colon adenomas from AA patients for both microsatellite instability (MSI) and the methylation status of SLC5A8 gene. This gene''s product is involved in the transport of butyrate that has anti-proliferative properties through its effects on histone acetylation and gene expression. A proteomic analysis to check the expressed histones in adenoma and normal tissues was also performed.Results
The analyzed samples displayed 82% (n = 41) methylation level of SLC5A8 gene in adenomas. The MSI-H (high) adenoma were about 18% (n = 9) while the rest were mostly MSS (microsatellite stable) with few MSI-L (Low). No association was found between SLC5A8 methylation and the MSI status. Also, there was no association between SLC5A8 methylation and the sex and age of the patients. However, there were more right sided adenomas with SLC5A8 methylation than the left sided ones. The proteomic analysis revealed distinct histone expression profiles between normal and adenoma tissues.Conclusion
SLC5A8 is highly methylated in AA colon adenomas which points to its potential use as a marker for early detection. The MSI rate is similar to that found in colon cancer tumors in AAs. These findings suggest that both processes stem from the same epigenetic and genetic events occurring at an early stage in colon carcinogenesis in AAs. 相似文献109.
Saeid Kalantari-Dehaghi Bahman Ebrahimi-Hosseinzadeh Zahra-Beagom Mokhtari-Hosseini Fahimeh Nojoki Javad Hamedi 《Preparative biochemistry & biotechnology》2013,43(3):286-297
AbstractCo-v-culture (co-cultivations of physically separated microbes that only interact through the air) systems were designed to investigate the effects of microbial volatile organic compounds (mVOCs) from about 20 different microbes, on a medicinal fungus, Ganoderma lucidum. For more accuracy in co-cultivations, a novel synchronized cultivation approach was tested for culturing G. lucidum. The hyphal growth of G. lucidum and the content of its ganoderic acids (GAs) were measured. In almost all of the co-v-cultures, there was an inhibiting effect on hyphal growth and a promoting effect on GAs contents. In inducing GAs production, Bacillus cereus PTCC 1247 and Pseudomonas aeruginosa UTMC 1404 were the most effective ones, as, compared to control cultures, GAs content increased 2.8 fold. Comparing different co-v-cultivations demonstrated that the concentrations of mVOCs, oxygen, and carbon dioxide were the main players in co-v-cultures. No correlation was found between hyphal growth and GAs production. Strains of the same species imposed totally different effects on hyphal growth or GAs production. This study has investigated the effects of mVOCs on G. lucidum for the first time. Moreover, it suggests that co-v-cultivation may be a promising biotechnological approach to improve the production in G. lucidum. 相似文献
110.
Shirin Toosi Zohreh Esmaeilzadeh Hojjat Naderi-Meshkin Asieh Heirani-Tabasi Mohammad Taghi Peivandi Javad Behravan 《Journal of cellular physiology》2019,234(11):20066-20071
Mesenchymal stem cells (MSCs) obtained from various sources have been used for different therapeutic applications including tissue regeneration. Reamer/irrigator/aspirator (RIA) has been increasingly used in recent years for the derivation of MSCs. Here in this investigation we have comparatively analyzed MSCs obtained from iliac crest bone marrow (ICBM) and RIA for their morphology, cluster determinant (CD) markers, and adipogenic differentiation capacity. MSCs were isolated, cultured, and purified from both sources and then flow cytometric studies were performed to study their characteristics. The differentiation potential of RIA and ICBM was examined by an Oil Red O staining protocol. Moreover, the tissue-specific markers related to adipogenesis were analyzed by real-time polymerase chain reaction (RT-PCR). The cells were cultured in the relevant induction medium and then adipogenic lineage differentiation was tested and confirmed for all MSC preparations. Additionally, analysis by flow cytometer was indicative of RIA derived MSCs (RIA-MSCs) having a more homogenous population than ICBM derived MSCs. The RIA-MSCs differentiation toward adipogenic lineage was more efficient compared with ICBM-MSCs. Direct comparative analysis of RIA to ICBM-MSCs indicated that the RIA-MSCs had a higher potential toward adipocyte lineage differentiation compared with ICBM-MSCs. 相似文献