全文获取类型
收费全文 | 91篇 |
免费 | 12篇 |
出版年
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2015年 | 6篇 |
2014年 | 2篇 |
2013年 | 8篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2007年 | 1篇 |
2006年 | 3篇 |
2005年 | 1篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1960年 | 1篇 |
排序方式: 共有103条查询结果,搜索用时 15 毫秒
1.
2.
3.
Receptor and G-protein-dependent regulation of turkey erythrocyte phosphoinositidase C 总被引:1,自引:0,他引:1
C P Downes C P Berrie P T Hawkins L Stephens J L Boyer T K Harden 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1988,320(1199):267-280
Several lines of experimental evidence indicate the involvement of a guanine nucleotide-dependent protein (G-protein) in the hormone-stimulated hydrolysis of phosphatidylinositol(4,5)-bisphosphate (PtdIns(4,5)P2). However, the shortcomings of available procedures for cell-free assay of hormone-stimulated phosphoinositidase C (PIC) have limited our current understanding of the molecular and mechanistic details of PIC regulation. We recently have proposed that turkey erythrocyte membranes may provide a valuable model system for studies of G-protein-dependent PtdIns(4,5)P2 hydrolysis. The membranes can be simply prepared from [3H]inositol-labelled erythrocytes and they contain a PIC activity that hydrolyses endogenous phosphoinositides and is exquisitively sensitive to guanine nucleotides. PtdIns(4,5)P2 is the principal substrate for this enzyme, there being relatively little direct hydrolysis of phosphatidylinositol 4-phosphate and no detectable hydrolysis of PtdIns. The membranes also contain a purinoceptor of the P2y subclass that is efficiently coupled to PtdIns(4,5)P2 hydrolysis both in intact cells and in the isolated membranes. 2-Methylthioadenosine trisphosphate (2-methyl-S-ATP), a specific P2y receptor agonist, has no effect upon PtdIns(4,5)P2 hydrolysis in the absence of guanine nucleotides, but greatly enhances both the potency and efficacy of PIC activation by guanine nucleotides such as GTP gamma S. GTP gamma S alone stimulates PIC activity only after a prolonged time-lag; the effect of increasing doses of 2-methyl-S-ATP is progressively to shorten this lag phase. These results suggest that the mechanism of G-protein activation involves acceleration of a nucleotide exchange reaction as has been demonstrated for the activation of adenylate cyclase in the same membrane preparation. As well as contributing valuable information on the substrate specificity of PIC and its mode of regulation by hormones, turkey erythrocytes provide a plentiful source of plasma membranes and may be useful for purification of the appropriate G-protein and PIC activities. 相似文献
4.
Induction of high-titer neutralizing antibodies, using hybrid human immunodeficiency virus V3-Ty viruslike particles in a clinically relevant adjuvant. 总被引:8,自引:5,他引:3
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
J C Griffiths E L Berrie L N Holdsworth J P Moore S J Harris J M Senior S M Kingsman A J Kingsman S E Adams 《Journal of virology》1991,65(1):450-456
The localization of neutralization determinants within the envelope glycoproteins of human immunodeficiency virus (HIV) has been largely achieved by immunizing small animals in conjunction with Freund's adjuvant. However, for eventual use in humans, candidate HIV vaccine components must also be efficacious in a nontoxic formulation. We describe here the production of hybrid Ty viruslike particles carrying the major neutralizing domain of HIV and demonstrate the induction of high-titer virus-neutralizing antibodies and an HIV-specific T-cell proliferative response after immunization in conjunction with aluminum hydroxide. As aluminum hydroxide and aluminum phosphate are the only adjuvants currently licensed for use in humans, these observations have implications for the development of an effective vaccine against HIV. 相似文献
5.
1. A screen for agonists capable of stimulating the formation of inositol phosphates in erythrocytes from 5-day-old chickens revealed the presence of a population of phosphoinositidase C-linked purinergic receptors. 2. If chicken erythrocytes prelabelled with [3H]Ins were exposed to a maximal effective dose of adenosine 5'-[beta-thio]diphosphate for 30 s, the agonist-stimulated increment in total [3H]inositol phosphates was confined to [3H]Ins(1,4,5)P3, Ins(1,3,4,5)P4 and InsP2. After 40 min stimulation, the radiolabelling of nearly all of the [3H]inositol phosphates that have been detected in these extracts [Stephens, Hawkins & Downes (1989) Biochem. J. 262, 727-737] had risen. However, some of these increases [especially those in Ins(3,4,5,6)P4 and Ins(1,3,4,5,6)P5] were accountable for almost entirely by increases in specific radioactivity rather than in mass. 3. The effect of purinergic stimulation on the rate of incorporation of [32P]Pi in the medium into the gamma-phosphate group of ATP and InsP4 and InsP5 was also measured. After 40 min stimulation, the incorporation of 32P into Ins(1,3,4,6)P4, Ins(1,3,4,5)P4, Ins(3,4,5,6)P4 and Ins(1,3,4,5,6)P5 was significantly elevated, whereas the mass of the last two and the specific radioactivity of the gamma-phosphate of ATP were unchanged compared with control erythrocyte suspensions. 4. In control suspensions of avian erythrocytes, the specific radioactivity of the individual phosphate moieties of Ins(1,3,4,6)P4 increased through the series 1, 6, 4 and 3 [Stephens & Downes (1990) Biochem. J. 265, 435-452]. This pattern of 32P incorporation is not the anticipated outcome of 6-hydroxy phosphorylation of Ins(1,3,4)P3 [the assumed route of synthesis of Ins(1,3,4,6)P4]. Although adenosine [beta-thio]diphosphate significantly stimulated the accumulation of [3H]Ins(1,3,4)P3, and despite the fact that avian erythrocyte lysates were shown to possess a chromatographically distinct, soluble, ATP-dependent, Ins(1,3,4)P3 6-hydroxykinase activity, purinergic stimulation of intact cells did not significantly alter the pattern of incorporation of [32P]Pi into the individual phosphate moieties of Ins(1,3,4,6)P4. These results suggest that the route of synthesis of this inositol phosphate species is not changed during the presence of an agonist. 相似文献
6.
Emile CL. Marnette Harm Houweling Herman Van Dam Jan Willem Erisman 《Biogeochemistry》1993,23(2):119-144
The chemical composition of surface waters of two Dutch moorland pools and of incident precipitation, was monitored from 1982
to 1990. For this period, sulfur and water budgets were calculated using a hydrochemical model developed for well-mixed non-stratifying
lakes. Total atmospheric deposition of S decreased significantly after 1986 at both locations. A model describing the sulfur
budget in terms of input, output and reduction/oxidation processes predicted a fast decrease of pool water SO4
2− concentrations after a decrease of atmospheric input. However, SO4
2− concentrations in the surface water was lowered only slightly or remained constant. Apparently a source within the lake caused
the unexpectedly high SO4
2− concentrations. The possible supply of SO4
2− from the sediment through regulation by (K-)Al-SO4 containing minerals or desorption of SO4
2− from positively charged surfaces in the sediment was evaluated. Solubility calculations of pore water with respect to alunite,
basaluminite and jurbanite indicated that SO4
2− concentration was not regulated by these minerals. It is suggested here (1) that desorption of SO4
2− from peaty sediments may account for the estimated SO4
2− supply provided that the adsorption complex is periodically recharged by partial oxidation of the upper bottom sediments
and (2) that because of exposure of a part of the pool bottom to the atmosphere during dry summers and subsequent oxidation
of reduced S, the amount of SO4
2− may be provided which complements the decreasing depositional SO4
2− input. In future research these two mechanisms need to be investigated. 相似文献
7.
Effect of Temperature on the Short Chain Fatty Acid-induced Inhibition of Lettuce Seed Germination 总被引:3,自引:2,他引:1
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In lettuce, Lactuca sativa short chain fatty acids (C6 - C9) vary in their effectiveness as inhibitors of germination according to temperature; the higher the temperature, the greater the inhibition. A linear relationship exists between temperature and the dose causing half-maximal germination. Nonanoic (C9) acid is the most effective. 相似文献
8.
Sulfate reduction and S-oxidation in a moorland pool sediment 总被引:3,自引:2,他引:1
In an oligotrophic moorland pool in The Netherlands, S cycling near the sediment/water boundary was investigated by measuring (1) SO4
2– reduction rates in the sediment, (2) depletion of SO4
2– in the overlying water column and (3) release of35S from the sediment into the water column. Two locations differing in sediment type (highly organic and sandy) were compared, with respect to reduction rates and depletion of SO4
2– in the overlying water.Sulfate reduction rates in sediments of an oligotrophic moorland pool were estimated by diagenetic modelling and whole core35SO4
2– injection. Rates of SO4
2– consumption in the overlying water were estimated by changes in SO4
2– concentration over time in in situ enclosures. Reduction rates ranged from 0.27–11.2 mmol m–2 d–1. Rates of SO4
2– uptake from the enclosed water column varied from –0.5, –0.3 mmol m–2 d–1 (November) to 0.43–1.81 mmol m–2 d–1 (July, August and April). Maximum rates of oxidation to SO4
2– in July 1990 estimated by combination of SO4
2– reduction rates and rates of in situ SO4
2– uptake in the enclosed water column were 10.3 and 10.5 mmol m–2 d–1 at an organic rich and at a sandy site respectively.Experiments with35S2– and35SO4
2– tracer suggested (1) a rapid formation of organically bound S from dissimilatory reduced SO4
2– and (2) the presence of mainly non SO4
2–-S derived from reduced S transported from the sediment into the overlying water. A35S2– tracer experiment showed that about 7% of35S2– injected at 1 cm depth in a sediment core was recovered in the overlying water column.Sulfate reduction rates in sediments with higher volumetric mass fraction of organic matter did not significantly differ from those in sediments with a lower mass fraction of organic matter.Corresponding author 相似文献
9.
10.
MARTIN CLÉMENT CAROLINE CHAMBERLAND JACQUELINE PÉRODIN RICHARD LEDUC GAÉTAN GUILLEMETTE EMANUEL ESCHER 《Journal of receptor and signal transduction research》2013,33(5-6):417-433
Several models of activation mechanisms were proposed for G protein-coupled receptors (GPCRs), yet no direct methods exist for their elucidation. The availability of constitutively active mutants has given an opportunity to study active receptor conformations within acceptable limits using models such as the angiotensin II type 1 (AT1)1 receptor mutant N111G-hAT1 which displays an important constitutive activity. Recently, by using methionine proximity assay, we showed for the hAT1 receptor that TMD III, VI, and VII form the ligand-binding pocket of the C-terminal amino acid of an antagonistic AngII analogue. In the present contribution, we investigated whether the same residues would also constitute the ligand-binding contacts in constitutively activated mutant (CAM) receptors. For this purpose, the same Met mutagenesis strategy was carried out on the N111G double mutants. Analysis of 43 receptors mutants in the N111G-hAT1 series, photolabeled and CNBr digested, showed that there were only subtle structural changes between the wt-receptor and its constitutively active form. 相似文献