全文获取类型
收费全文 | 45篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
50篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2012年 | 1篇 |
2011年 | 1篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 2篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1965年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有50条查询结果,搜索用时 0 毫秒
11.
Candida rugosa lipase resolved trans-2-phenylcyclohexan-1-ol. A commercial and a laboratory preparation were compared and better results were obtained with the latter (E >200). Both enzyme preparations were strongly dependent on the substrate concentration for their enantioselectivity. This effect could be due to the presence of an esterase activity unspecific for trans-2-phenylcyclohexan-1-ol. © Rapid Science Ltd. 1998 相似文献
12.
Mehri Ghasabi Behzad Mansoori Ali Mohammadi Pascal HG Duijf Navid Shomali Naghmeh Shirafkan Ahad Mokhtarzadeh Behzad Baradaran 《Journal of cellular physiology》2019,234(3):2152-2168
Development of drug resistance has considerably limited the efficacy of cancer treatments, including chemotherapy and targeted therapies. Hence, understanding the molecular mechanisms underpinning the innate or the acquired resistance to these therapies is critical to improve drug efficiency and clinical outcomes. Several studies have implicated microRNAs (miRNA) in this process. MiRNAs repress gene expression by specific binding to complementary sequences in the 3' region of target messenger RNAs (mRNAs), followed by target mRNA degradation or blocked translation. By targeting molecules specific to a particular pathway within tumor cells, the new generation of cancer treatment strategies has shown significant advantages over conventional chemotherapy. However, the long-term efficacy of targeted therapies often remains poor, because tumor cells develop resistance to such therapeutics. Targeted therapies often involve monoclonal antibodies (mAbs), such as those blocking the ErB/HER tyrosine kinases, epidermal growth factor receptor (cetuximab) and HER2 (trastuzumab), and those inhibiting vascular endothelial growth factor receptor signaling (e.g., bevacizumab). Even though these are among the most used agents in tumor medicine, clinical response to these drugs is reduced due to the emergence of drug resistance as a result of toxic effects in the tumor microenvironment. Research on different types of human cancers has revealed that aberrant expression of miRNAs promotes resistance to the aforementioned drugs. In this study, we review the mechanisms of tumor cell resistance to mAb therapies and the role of miRNAs therein. Emerging treatment strategies combine therapies using innovative miRNA mimics or antagonizers with conventional approaches to maximize outcomes of patients with cancer. 相似文献
13.
Background
Paired mushroom bodies, an unpaired central complex, and bilaterally arranged clusters of olfactory glomeruli are among the most distinctive components of arthropod neuroarchitecture. Mushroom body neuropils, unpaired midline neuropils, and olfactory glomeruli also occur in the brains of some polychaete annelids, showing varying degrees of morphological similarity to their arthropod counterparts. Attempts to elucidate the evolutionary origin of these neuropils and to deduce an ancestral ground pattern of annelid cerebral complexity are impeded by the incomplete knowledge of annelid phylogeny and by a lack of comparative neuroanatomical data for this group. The present account aims to provide new morphological data for a broad range of annelid taxa in order to trace the occurrence and variability of higher brain centers in segmented worms.Results
Immunohistochemically stained preparations provide comparative neuroanatomical data for representatives from 22 annelid species. The most prominent neuropil structures to be encountered in the annelid brain are the paired mushroom bodies that occur in a number of polychaete taxa. Mushroom bodies can in some cases be demonstrated to be closely associated with clusters of spheroid neuropils reminiscent of arthropod olfactory glomeruli. Less distinctive subcompartments of the annelid brain are unpaired midline neuropils that bear a remote resemblance to similar components in the arthropod brain. The occurrence of higher brain centers such as mushroom bodies, olfactory glomeruli, and unpaired midline neuropils seems to be restricted to errant polychaetes.Conclusions
The implications of an assumed homology between annelid and arthropod mushroom bodies are discussed in light of the 'new animal phylogeny'. It is concluded that the apparent homology of mushroom bodies in distantly related groups has to be interpreted as a plesiomorphy, pointing towards a considerably complex neuroarchitecture inherited from the last common ancestor, Urbilateria. Within the annelid radiation, the lack of mushroom bodies in certain groups is explained by widespread secondary reductions owing to selective pressures unfavorable for the differentiation of elaborate brains. Evolutionary pathways of mushroom body neuropils in errant polychaetes remain enigmatic. 相似文献14.
15.
16.
Raúl Chiozzone Ricardo González Donatella Armentano Juan Faus 《Inorganica chimica acta》2006,359(7):2194-2200
The reaction of K2[ReX6] (X = Cl, Br) with oxalic acid and triethylamine in dimethylformamide solution yields the substituted complexes [ReX4(ox)]2− and cis-[ReX2(ox)2]2−, which can be obtained separately depending on the amount of added amine. The crystal structures of (PPh4)2[ReBr4(ox)], cis-(PPh4)2[ReBr2(ox)2] and cis-(AsPh4)2[ReCl2(ox)2] have been determined by single-crystal X-ray diffraction. The anionic complexes are octahedral with only slight distortions. The direct isolation of the pure complexes as well as the formation of only the cis isomers - without the presence of trans isomers and/or [Re(ox)3]2− - is probably due to the kinetic inertness of Re(IV)-X bonds, which increases with the number of oxalato ligands bound to the metal ion. 相似文献
17.
Adaptation to hypoxic stress provokes activation of the hypoxia-inducible-factor-1 (HIF-1) which mediates gene expression of, e.g., erythropoietin or vascular endothelial growth factor. Detailed information on signaling pathways that stabilize HIF-1 is missing, but reactive oxygen species degrade the HIF-1 alpha subunit, whereas phosphorylation causes its stabilization. It was believed that hypoxia resembles the only HIF-1 inducer but recent evidence characterized other activators of HIF-1 such as nitric oxide (NO). Herein, we concentrated on NO-evoked HIF-1 induction as a heretofore unappreciated inflammatory response in association with massive NO formation. We demonstrated that S-nitrosoglutathione induces HIF-1 alpha accumulation and concomitant DNA binding. The response was attenuated by the kinase inhibitor genistein and blockers of phosphatidylinositol 3-kinase such as Ly 294002 or wortmannin. Whereas mitogen-activated protein kinases were not involved, we noticed phosphorylation/activation of Akt in correlation with HIF-1 alpha stabilization. NO appears to regulate HIF-1 alpha via the PI 3K/Akt pathway under normoxic conditions. 相似文献
18.
Mohamed F Ismail Doaa A Ali Augusta Fernando Mohamed E Abdraboh Rajiv L Gaur Wael M Ibrahim Madhwa HG Raj Allal Ouhtit 《International journal of biological sciences》2009,5(4):377-387
Spirulina platensis (SP) is a filamentous cyanobacterium microalgae with potent dietary phyto-antioxidant, anti-inflammatory and anti-cancerous properties. The present study aimed to investigate the chemopreventive effect of SP against rat liver toxicity and carcinogenesis induced by dibutyl nitrosamine (DBN) precursors, and further characterized its underlying mechanisms of action in HepG2 cell line. Investigation by light and electron microscopy showed that DBN treatment induced severe liver injury and histopathological abnormalities, which were prevented by SP supplementation. The incidence of liver tumors was significantly reduced from 80 to 20% by SP. Immunohistochemical results indicated that both PCNA and p53 were highly expressed in the liver of DBN-treated rats, but were significantly reduced by SP supplementation. Molecular analysis indicated that SP treatment inhibited cell proliferation, which was accompanied by increased p21 and decreased Rb expression levels at 48hrs post-treatment. In addition, SP increased Bax and decreased Bcl-2 expression, indicating induction of apoptosis by 48hrs. This is the first report of the in vivo chemopreventive effect of SP against DBN-induced rat liver cytotoxicity and carcinogenesis, suggesting its potential use in chemoprevention of cancer. 相似文献
19.
Paulo HG Mansur Lacordaire KP Cury José OB Leite Adriano A Pereira Nilson Penha-Silva Adriano O Andrade 《Biomedical engineering online》2010,9(1):29
Background
The main problem of tremor is the damage caused to the quality of the life of patients, especially those at more advanced ages. There is not a consensus yet about the origins of this disorder, but it can be examined in the correlations between the biological signs of aging and the tremor characteristics. 相似文献20.
Holger Diedrichs Carsten Zobel Peter Theissen Michael Weber Athanassios Koulousakis Harald Schicha Robert HG Schwinger 《Trials》2005,6(1):1-7