全文获取类型
收费全文 | 166篇 |
免费 | 12篇 |
出版年
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 9篇 |
2015年 | 9篇 |
2014年 | 3篇 |
2013年 | 20篇 |
2012年 | 9篇 |
2011年 | 7篇 |
2010年 | 5篇 |
2009年 | 6篇 |
2008年 | 9篇 |
2007年 | 5篇 |
2006年 | 2篇 |
2005年 | 9篇 |
2003年 | 1篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有178条查询结果,搜索用时 46 毫秒
151.
Chattopadhyay MB Mukherjee S Kulkarni I Vijayan V Doloi M Kanjilal N Chatterjee M 《Cancer cell international》2005,5(1):16
Combined effect of vanadium and beta-carotene on rat liver DNA-chain break and Proton induced X-ray emission (PIXE) analysis
was studied during a necrogenic dose (200 mg/kg of body weight) of Diethyl Nitrosamine (DENA) induced rat liver carcinogenesis.
Morphological and histopathological changes were observed as an end point biomarker. Supplementation of vanadium (0.5 ppm
ad libitum) in drinking water and beta-carotene in the basal diet (120 mg/Kg of body weight) were performed four weeks before DENA treatment
and continued till the end of the experiment (16 weeks). PIXE analysis revealed the restoration of near normal value of zinc,
copper, and iron, which were substantially altered when compared to carcinogen treated groups. Supplementation of both vanadium
and beta-carotene four weeks before DENA injection was found to offer significant (64.73%, P < 0.001) protection against generation
of single-strand breaks when compared with the carcinogen control counter parts. A significant stabilization of hepatic architecture
of the cells was observed as compared to carcinogen control in vanadium plus beta-carotene treated group. This study thus
suggests that vanadium, a prooxidant but potential therapeutic agent yield safe and effective pharmacological formulation
with beta-carotene, an antioxidant, in the inhibition of experimental rat hepatocarcinogenesis. 相似文献
152.
Jenett-Siems K Weigl R Böhm A Mann P Tofern-Reblin B Ott SC Ghomian A Kaloga M Siems K Witte L Hilker M Müller F Eich E 《Phytochemistry》2005,66(12):1448-1464
The occurrence and distribution of tropane and biogenetically related pyrrolidine alkaloids in 18 Merremia species of paleo-, neo-, and pantropical occurrence have been studied. The extensive GC-MS study included members of almost all sections of the genus and has been carried out with epigeal vegetative parts as well as with roots. It comprises altogether 74 tropanes and 13 pyrrolidines including nicotine. Along with datumetine known already from a solanaceous species, the study led to the isolation (from M. dissecta and M. guerichii, respectively) and structure elucidation (spectral data) of four novel 3alpha-acyloxytropanes, merresectines A-D: 3alpha-(4-methoxybenzoyloxy)nortropane (A), 3alpha-kurameroyloxytropane (B), 3alpha-nervogenoyloxytropane (C), 3alpha-[4-(beta-D-glucopyranosyloxy)-3-methoxy-5-(3-methyl-2-butenyl)benzoyloxy]tropane (beta-d-glucoside of D). Moreover, the novel 3alpha,6beta-di-(4-methoxybenzoyloxy)tropane (merredissine) has been isolated from M. dissecta and structurally elucidated. In addition the structures of datumetine and merresectine A could be confirmed by synthesis. Spectral data for two known 3alpha-acyloxytropanes (merresectine E beta-D-glucoside, 4'-dihydroconsabatine) and one known 3beta-acyloxytropane (concneorine) are documented for the first time. The structures of three further merresectines (F-H) have been determined by mass spectrometry. Furthermore, the linkage (2',3- and 2',4-, respectively) of two position isomer N-methylpyrrolidinylhygrines was proven by synthesis. The results of the study contribute to the solution of infrageneric taxonomic problems. Whereas all species yield pyrrolidine alkaloids without suitably differentiating results the diverging occurrence of tropane alkaloids leads to three groups of sections: (1) taxa free of tropanes, (2) taxa with simple tropanes, and (3) taxa with merresectines in addition to simple tropanes. 相似文献
153.
154.
Paris I Dagnino-Subiabre A Marcelain K Bennett LB Caviedes P Caviedes R Azar CO Segura-Aguilar J 《Journal of neurochemistry》2001,77(2):519-529
The mechanism of copper (Cu) neurotoxicity was studied in the RCSN-3 neuronal dopaminergic cell line, derived from substantia nigra of an adult rat. The formation of a Cu-dopamine complex was accompanied by oxidation of dopamine to aminochrome. We found that the Cu-dopamine complex mediates the uptake of (64)CuSO(4) into the Raúl Caviedes substantia nigra-clone 3 (RCSN3) cells, and it is inhibited by the addition of excess dopamine (2 m M) (63%, p < 0.001) and nomifensine (2 microM) (77%, p < 0.001). Copper sulfate (1 m M) alone was not toxic to RCSN-3 cells, but was when combined with dopamine or with dicoumarol (95% toxicity; p < 0.001) which inhibits DPNH and TPNH (DT)-diaphorase. Electron spin resonance (ESR) spectrum of the 5,5-dimethylpyrroline-N-oxide (DMPO) spin trap adducts showed the presence of a C-centered radical when incubating cells with dopamine, CuSO(4) and dicoumarol. A decrease in the expression of CuZn-superoxide dismutase and glutathione peroxidase mRNA was observed when RCSN-3 cells were treated with CuSO(4), dopamine, or CuSO(4) and dopamine. However, the mRNA expression of glutathione peroxidase remained at control levels when the cells were treated with CuSO(4), dopamine and dicoumarol. The regulation of catalase was different since all the treatments with CuSO(4) increased the expression of catalase mRNA. Our results suggest that copper neurotoxicity is dependent on: (i) the formation of Cu-dopamine complexes with concomitant dopamine oxidation to aminochrome; (ii) dopamine-dependent Cu uptake; and (iii) one-electron reduction of aminochrome. 相似文献
155.
156.
Corneal angiogenesis and lymphangiogenesis are induced by vascular endothelial growth factors (VEGFs) signaling through its receptors VEGFR-1, -2, and -3. Endostatin is a peptide antagonist of these receptors that causes inhibition of bFGF-induced corneal angiogenesis and lymphangiogenesis. Here we show that binding of VEGF-C and endostatin to recombinant VEGFR-3 is competitive. Alignments of the primary amino acid sequences of VEGF-C and the C-terminal endostatin peptide (mEP: LEQKAASCHNSYIVLCIENSFMTSFSK) identified two conserved cysteine residues separated by seven amino acids. Peptides of VEGF-C and mEP containing these conserved residues bound toVEGFR-3. However, substitution of alanine for either of the cysteines in the mEP peptide perturbed the secondary structure, and this mutated peptide was unable to bind to VEGFR-3. Analysis by surface plasmon resonance demonstrated that the binding of the mEP peptide for recombinant VEGFR-3 had a Ka of 1.41x107M-1s-1, Kd of 0.6718 s-1, and a KD of 4.78x10-8M. Characterization of the mechanism of endostatin binding to VEGFR-3 may lead to the development of novel therapies for lymphangiogenesis-related disorders, such as transplant rejection, lymphedema, and cancer metastasis. 相似文献
157.
158.
Korobkova EA Nemeth J Cadougan M Venkatratnam A Bassit M Azar N 《Bioorganic & medicinal chemistry》2012,20(1):340-345
Tricyclic antidepressants (TCAs), along with phenothyazines and some industrial chemicals, are shown to react with enzymes that exhibit peroxidase activity. These reactions result in the formation of reactive intermediates having unpaired electrons. The peroxidase oxidation and reactivity of two TCAs, desipramine and clomipramine, were investigated. As a model of peroxidase, horseradish peroxidase (HRP) was employed. The products of the peroxidase catalyzed oxidation of desipramine and clomipramine were identified as N-dealkylated compounds iminodibenzyl and 3-chloroiminodibenzyl using the GC/MS technique. Both drugs formed broad UV/vis absorption spectra in the presence of HRP and H(2)O(2), indicating the formation of a radical cations-reactive intermediate of the oxidation reaction. The dynamics of the formation of the desipramine intermediate was studied using UV/vis spectroscopy. The extinction coefficient was measured for the reactive intermediate, 7.80×10(3)M(-1)cm(-1), as well as the apparent Michaelis-Menten and catalytic constants, 4.4mM and 2.3s(-1), respectively. Both desipramine and clomipramine degraded DNA in the presence of HRP/H(2)O(2), as was revealed by agarose gel electrophoresis and PCI extraction. Manipulating the kinetic parameters of drug's radical formation and determining the extent of degradation to biomolecules could be potentially used for designing effective agents exhibiting specific reactivity. 相似文献
159.
Saud N. Al Sifri Wael Almahmeed Sami Azar Osama Okkeh Peter Bramlage Claus Jünger Islam Halawa Baishali Ambegaonkar Sameh Wajih Philippe Brudi 《PloS one》2014,9(1)
Background
Therapeutic intervention with low-density lipoprotein cholesterol-lowering agents known as statins has been demonstrated to reduce cardiovascular risk. However, many patients on statin treatment have persistent dyslipidemia and remain at a high risk of cardiovascular disease. Therefore, the objective of this study was to assess the frequency of lipid abnormalities in patients receiving chronic statin treatment.Methods
As part of an international, cross-sectional, observational study, DYSIS-Middle East enrolled 2,182 patients in the United Arab Emirates (UAE), Saudi Arabia, Lebanon and Jordan. All patients were over 45 years of age and had been on statin treatment for at least three months. Data on demographics, lipid parameters and cardiovascular risk profile were recorded. Cardiovascular risk was defined according the guidelines of the European Society of Cardiology.Results
The majority of patients (82.6%) were classified as being at very high risk of cardiovascular events, and 61.8% of all patients did not attain LDL-C target levels. Low high-density lipoprotein cholesterol levels and elevated triglyceride levels were noted in 55.5% and 48.5% of patients, respectively. Multivariate logistical regression modeling indicated that factors independently associated with LDL-C levels not being at goal were lifestyle choices, diabetes mellitus, ischemic heart disease, and blood pressure ≥ 140/90 mmHg.Conclusions
Almost two-thirds of statin-treated patients in the United Arab Emirates, Saudi Arabia, Lebanon and Jordan had inadequately controlled lipid levels. More comprehensive surveillance, awareness and treatment regimens, as well as modification of lifestyle choices, is necessary to halt the rise in cardiovascular disease-related mortality. 相似文献160.
Hunter NB Moseley 《BMC bioinformatics》2010,11(1):139