全文获取类型
收费全文 | 84篇 |
免费 | 14篇 |
出版年
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 7篇 |
2012年 | 8篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 11篇 |
2007年 | 3篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1998年 | 8篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1992年 | 3篇 |
1988年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1975年 | 3篇 |
1971年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有98条查询结果,搜索用时 828 毫秒
1.
In a variety of tumour systems, individuals carrying progressively growing neoplasms have lymphoid cells with a specific cytotoxic effect on cultured tumour cells from the same individual1–4. Since the sera of tumour-bearing individuals have been shown to prevent tumour cell destruction by immune lymphocytes in vitro2,5–8 and since this serum blocking activity appears early in primary and transplant tumour development5,7, it has been suggested that the appearance of this serum blocking activity might be responsible for the progressive growth of tumours in individuals having cytotoxic lymphocytes. Counteraction of this blocking activity would thus be of primary importance in facilitating the function of an already existing or bolstered cell-mediated immunity. The serum blocking activity might be inhibited in various ways, by preventing the formation of blocking antibody or by interfering with its action (“unblocking”), as demonstrated in Moloney sarcoma regressor sera9. This type of serum also has a therapeutic effect on Moloney sarcomas in vivo10,11, which has been tentatively attributed to its unblocking activity8,9 or, possibly, to a complement-dependent cytotoxicity10. Tumour growth in the Moloney sarcoma system, however, might be due in part to continuous recruitment of neoplastic cells by virus-induced transformation and so the therapeutic effect could be due to a virus-neutralizing serum activity9,10. 相似文献
2.
On the mechanism of ATP-induced shape changes in the human erythrocyte membranes: the role of ATP 下载免费PDF全文
In the preceding paper (Sheetz, M. and S.J. Singer. 1977. J Cell Biol. 73:638-646) it was shown that erythrocyte ghosts undergo pronounced shape changes in the presence of mg-ATP. The biochemical effects of the action of ATP are herein examined. The biochemical effects of the action of ATP are herein examined. Phosphorylation by ATP of spectrin component 2 of the erythrocyte membrane is known to occur. We have shown that it is only membrane protein that is significantly phosphorylated under the conditions where the shape changes are produced. The extent of this phosphorylation rises with increasing ATP concentration, reaching nearly 1 mol phosphoryle group per mole of component 2 at 8mM ATP. Most of this phosphorylation appears to occur at a single site on the protein molecule, according to cyanogen bromide peptide cleavage experiments. The degree of phosphorylation of component 2 is apparently also regulated by a membrane-bound protein phosphatase. This activity can be demonstrated in erythrocyte ghosts prepared from intact cells prelabeled with [(32)P]phosphate. In addition to the phosphorylation of component 2, some phosphorylation of lipids, mainly of phosphatidylinositol, is also known to occur. The ghost shape changes are, however, shown to be correlated with the degree of phosphorylation of component 2. In such experiment, the incorporation of exogenous phosphatases into ghosts reversed the shape changes produced by ATP, or by the membrane-intercalating drug chlorpromazine. The results obtained in this and the preceding paper are consistent with the proposal that the erythrocyte membrane possesses kinase and phosphates activities which produce phosphorylation and dephosphorylation of a specific site on spectrin component 2 molecules; the steady-state level of this phosphorylation regulates the structural state of the spectrin complex on the cytoplasmic surface of the membrane, which in turn exerts an important control on the shape of the cell. 相似文献
3.
Gold salts and phenylbutazone selectively inhibit the synthesis of PGF2α and PGE2 respectively. Lowered production of one prostaglandin species is accompanied by an increased production of the other. Selective inhibition by these drugs was observed in the presence of adrenaline, reduced glutathione and copper sulphate under conditions when most anti-inflammatory compounds inhibited PGE2 and PGF2α syntheses equally. It is postulated that selective inhibitors may have a different mode of action
and beneficial effects may be related to the endogenous ratio of PGE to PGF required for normal function. 相似文献
4.
5.
Pasquier CM; Promponas VI; Varvayannis NJ; Hamodrakas SJ 《Bioinformatics (Oxford, England)》1998,14(8):749-750
Summary : FT is a tool written in C++, which implements the Fourier
analysis method to locate periodicities in aminoacid or DNA sequences. It
is provided for free public use on a WWW server with a Java interface.
Availability : The server address is http://o2.db. uoa.gr/FT Contact :
shamodr@atlas.uoa.gr
相似文献
6.
The pathogenesis underlying the selective degeneration of nigral dopaminergic neurons in Parkinson's disease is not fully understood but several lines of evidence implicate the role of oxidative stress and mitochondrial dysfunction. Depletion in levels of the thiol reducing agent glutathione (GSH + GSSG) is the earliest reported biochemical event to occur in the Parkinsonian substantia nigra prior to selective loss of complex I (CI) activity associated with the disease believed to contribute to subsequent dopaminergic cell death. Recent studies from our laboratory have demonstrated that acute reduction in both cellular and mitochondrial glutathione levels results in increased oxidative stress and a decrease in mitochondrial function linked to a selective decrease in CI activity through an NO-mediated mechanism (Jha, N.; Jurma, O.; Lalli, G.; Liu, Y.; Pettus, E. H.; Greenamyre, J. T.; Liu, R. M.; Forman, H. J.; Andersen, J. K. Glutathione depletion in PC12 results in selective inhibition of mitochondrial complex I activity. Implications for Parkinson's disease J. Biol. Chem. 275: 26096-26101; 2000. Hsu, M.; Srinivas, B.; Kumar, J.; Subramanian, R.; Andersen, J. Glutathione depletion resulting in selective mitochondrial complex I inhibition in dopaminergic cells is via an NO-mediated pathway not involving peroxynitrite: implications for Parkinson's disease J. Neurochem. 92: 1091-1103.2005.). However, the effect of prolonged glutathione depletion on dopaminergic cells is not known. In this present study, using low concentrations of buthionine-S-sulfoximine, a chemical inhibitor of the de novo glutathione synthesizing enzyme glutamate cysteine ligase, we developed a chronic model in which glutathione depletion in dopaminergic N27 cells for a 7-day period was found to lead to inhibition of CI activity via a peroxynitrite-mediated event which is reversible by the thiol reducing agent, dithiothreitol, and coincides with increased S-nitrosation of mitochondrial proteins. 相似文献
7.
Jasmonic acid induced changes in protein pattern, antioxidative enzyme activities and peroxidase isozymes in peanut seedlings 总被引:1,自引:0,他引:1
G. J. Kumari A. M. Reddy S. T. Naik S. G. Kumar J. Prasanthi G. Sriranganayakulu P. C. Reddy Chinta Sudhakar 《Biologia Plantarum》2006,50(2):219-226
Protein pattern, ammonia content, glutamine synthetase activity, lipid peroxidation, superoxide dismutase, catalase, peroxidase
and peroxidase isoforms were studied in the leaves and roots of 7-d-old peanut (Arachis hypogaea L. cv. JL-24) seedlings treated by 25, 100 and 250 μM jasmonic acid (JA). SDS-PAGE protein profile of leaves and roots after
JA application showed a significant increase in 18, 21, 30, 45, 47 and 97.4 kDa proteins and significant decrease in 22 and
36 kDa proteins. Pathogenesis related PR-18 was specific in leaves at 250 μM JA and PR-21 have cross reacted differently with
21 and 30 kDa proteins in leaves and roots treated by all JA concentrations. Further, the immunoblot analysis with glutamine
synthetase, GS-45 antibodies revealed a specific cross reaction with 45 and 47 kDa proteins of both control and JA treated
leaves, however, higher at 100 and 250 μM JA treated leaves than control ones. Further, the malondialdehyde (MDA) content
significantly increased in leaves and roots treated with JA, indicated membrane damage with JA treatments that led to the
generation of peroxidation products. The peroxidase isozymic pattern showed two specific isoforms. Besides, the activities
of SOD and catalase were significantly elevated in JA treated leaves. 相似文献
8.
Fulminant hepatic failure (FHF) is an acute form of hepatic encephalopathy resulting from severe inflammatory or necrotic
liver damage without any previously established liver damage. This develops as a complication due to viral infections, and
drug abuse. FHF also occurs in acute disorders like Reye’s syndrome. Although the exact mechanisms in the etiology of FHF
are not understood, elevated levels of brain ammonia have been consistently reported. Such increased ammonia levels are suggested
to alter neurotransmission signals and impair cerebral energy metabolism due to mitochondrial dysfunctions. In the present
study we have examined the role of cerebral electron transport chain complexes, including complex I, II, III IV, and pyruvate
dehydrogenase in the non-synaptic mitochondria isolated from the cortex of the thioacetamide-induced FHF rats. Further, we
have examined if the structure of mitochondria is altered. The results of the current study demonstrated a decrease in the
activity of the complex I by 31 and 48% at 18 and 24 h respectively after the thioacetamide injection. Similarly, the activity
of electron transport chain complex III was inhibited by 35 and 52% respectively, at 18 and 24 h, respectively. The complex
II and complex IV, on the other hand, revealed unaltered activity. Further the activity of pyruvate dehydrogenase at 18 and
24 h after the induction of FHF was inhibited by 29 and 43%, respectively. Our results also suggest mitochondrial swelling
in FHF induced rats. The inhibition of the respiratory complexes III and I and pyruvate dehydrogenase might lead to the increased
production of free radical resulting in oxidative stress and cerebral energy disturbances thereby leading to mitochondrial
swelling and further contributing to the pathogenesis of FHF. 相似文献
9.
P. Chandra Obul Reddy G. Sairanganayakulu M. Thippeswamy P. Sudhakar Reddy M.K. Reddy Chinta Sudhakar 《Plant science》2008,175(3):372-384
Abiotic stresses adversely affect the agricultural productivity worldwide. Horsegram (Macrotyloma uniflorum (Lam.) Verdc.) is a legume crop that can tolerate severe adverse environmental conditions such as drought, salinity and heavy metal contamination. As a first step towards characterization of genes that contribute to combating abiotic stresses, construction and analysis of subtracted cDNA library is reported here. Using this strategy a total of 1050 ESTs were isolated, sequenced, 959 high quality ESTs were obtained and clustered. Further, our analysis revealed that of these 531 sequences are unique and 30% of these have no homology to known proteins in the database. This observation has great relevance since horsegram is a stress-adapted legume crop. Further, to validate the identified differentially expressed genes, expression profiles of selected clones were analyzed using reverse-northern, northern blot analysis and we show that indeed these clones are differentially expressed under various abiotic stress conditions. The implications of the analyzed genes in abiotic stress tolerance also discussed. 相似文献
10.
Amiloride does not alter NaCl avoidance in Fischer-344 rats 总被引:2,自引:2,他引:0
Fischer-344 (F-344) rats differ from other common rat strains in that they
fail to show any preference for NaCl at any concentration in two- bottle
preference tests. Because 100 microM amiloride partially blocks the
NaCl-evoked chorda tympani (CT) response in electrophysiological studies,
we tested NaCl preference (0.068-0.273 M) in F-344 rats with and without
100 microM amiloride solution as the solvent. A third group was tested with
unadulterated NaCl solutions following CT transection. Amiloride had no
significant effect on the NaCl preference-aversion function, whereas CT
transection significantly reduced NaCl avoidance. These results suggest
that the amiloride-sensitive component of the NaCl response is not
necessary for F-344 rats to display avoidance of NaCl, but the entire CT
input is.
相似文献