全文获取类型
收费全文 | 70篇 |
免费 | 11篇 |
出版年
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 5篇 |
2013年 | 2篇 |
2012年 | 5篇 |
2011年 | 3篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 4篇 |
2007年 | 5篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1977年 | 3篇 |
1972年 | 1篇 |
排序方式: 共有81条查询结果,搜索用时 15 毫秒
1.
Free and polymerized tubulin in cultured bone cells and Chinese hamster ovary cells: the influence of cold and hormones 总被引:1,自引:1,他引:0
A low pH method of liposome-membrane fusion (Schneider et al., 1980, Proc. Natl. Acad. Sci. U. S. A. 77:442) was used to enrich the mitochondrial inner membrane lipid bilayer 30-700% with exogenous phospholipid and cholesterol. By varying the phospholipid-to- cholesterol ratio of the liposomes it was possible to incorporate specific amounts of cholesterol (up to 44 mol %) into the inner membrane bilayer in a controlled fashion. The membrane surface area increased proportionally to the increase in total membrane bilayer lipid. Inner membrane enriched with phospholipid only, or with phospholipid plus cholesterol up to 20 mol %, showed randomly distributed intramembrane particles (integral proteins) in the membrane plane, and the average distance between intramembrane particles increased proportionally to the amount of newly incorporated lipid. Membranes containing between 20 and 27 mol % cholesterol exhibited small clusters of intramembrane particles while cholesterol contents above 27 mol % resulted in larger aggregations of intramembrane particles. In phospholipid-enriched membranes with randomly dispersed intramembrane particles, electron transfer activities from NADH- and succinate-dehydrogenase to cytochrome c decreased proportionally to the increase in distance between the particles. In contrast, these electron- transfer activities increased with decreasing distances between intramembrane particles brought about by cholesterol incorporation. These results indicate that (a) catalytically interacting redox components in the mitochondrial inner membrane such as the dehydrogenase complexes, ubiquinone, and heme proteins are independent, laterally diffusible components; (b) the average distance between these redox components is effected by the available surface area of the membrane lipid bilayer; and (c) the distance over which redox components diffuse before collision and electron transfer mediates the rate of such transfer. 相似文献
2.
Movements and associations of ribosomal subunits in a secretory cell during growth inhibition by starvation
下载免费PDF全文
![点击此处可从《The Journal of cell biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In Chironomus tentans salivary gland cells, the cytoplasm can be dissected into concentric zones situated at increasing distances from the nuclear envelope. After RNA labeling, the newly made ribosomal subunits are found in the cytoplasm mainly in the neighborhood of the nucleus with a gradient of increasing abundance towards the periphery of the cell. The gradient for the small subunit lasts for a few hours and disappears entirely after treatment with puromycin. The large subunit also forms a gradient but one which is only partially abolished by puromycin. The residual gradient which which is resistant to the addition of the drug is probably due to the binding of some large ribosomal units to the membranes of the endoplasmic reticulum (J.-E. Edstrom and u. Lonn. 1976. J. Cell Biol. 70:562-572, and U. Lonn and J.-E. Edstrom. 1976. J. Cell. Biol. 70:573-580). If growth is inhibited by starvation, only the puromycin-sensitive type gradient is observed for the large subunit, suggesting that the attachment of these newly made subunits to the endoplasmic reticulum membranes will not occur. If, on the other hand, the drug-resistant gradient is allowed to form in feeding animals, it is conserved during a subsequent starvation for longer periods than in control feeding animals. This observation provides a further support for an effect of starvation on the normal turnover of the large subunits associated with the endoplasmic reticulum. These results also indicate a considerable structural stability in the cytoplasm of these cells worth little or no gross redistribution of cytoplasmic structures over a period of at least 6 days. 相似文献
3.
In cytosol-like medium (CLM) with a free [Ca(2+)] of 200 nm, a supramaximal concentration of inositol 1,4,5-trisphosphate (IP(3)) (30 microm) evoked (45)Ca(2+) release from type 3 IP(3) receptors only after a latency of 48 +/- 6 ms; this latency could not be reduced by increasing the IP(3) concentration. In CLM containing a low free [Ca(2+)] ( approximately 4 nm), 300 microm IP(3) evoked (45)Ca(2+) release after a latency of 66 +/- 11 ms; this was reduced to 14 +/- 3 ms when the [Ca(2+)] was 1 mm. Preincubation with CLM containing 100 microm Ca(2+) caused a rapid (half-time = 33 +/- 9 ms), complete, and fully reversible inhibition that could not be overcome by a high concentration of IP(3) (300 microm). Hepatic (type 2) IP(3) receptors were not inhibited by Ca(2+) once they had bound IP(3), but 100 microm Ca(2+) rapidly inhibited type 3 IP(3) receptors whether it was delivered before addition of IP(3) or at any stage during a response to IP(3). Ca(2+) increases the affinity of IP(3) for hepatic receptors by slowing IP(3) dissociation, but Ca(2+) had no effect on IP(3) binding to type 3 receptors. The rate of inhibition of type 3 IP(3) receptors by Ca(2+) was faster than the rate of IP(3) dissociation, and occurred at similar rates whether receptors had bound a high (adenophostin) or low affinity (3-deoxy-3-fluoro-IP(3)) agonist. Dissociation of agonist is not therefore required for Ca(2+) to inhibit type 3 IP(3) receptors. We conclude that type 2 and 3 IP(3) receptors are each biphasically regulated by Ca(2+), but by different mechanisms. For both, IP(3) binding causes a stimulatory Ca(2+)-binding site to be exposed allowing Ca(2+) to bind and open the channel. IP(3) binding protects type 2 receptors from Ca(2+) inhibition, but type 3 receptors are inhibited by Ca(2+) whether or not they have IP(3) bound. Increases in cytosolic [Ca(2+)] will immediately inhibit type 3 receptors, but inhibit type 2 receptors only after IP(3) has dissociated. 相似文献
4.
Gene expression profiling in the adult Down syndrome brain 总被引:4,自引:0,他引:4
5.
Baart GJ Zomer B de Haan A van der Pol LA Beuvery EC Tramper J Martens DE 《Genome biology》2007,8(7):R136
Background
Neisseria meningitidis is a human pathogen that can infect diverse sites within the human host. The major diseases caused by N. meningitidis are responsible for death and disability, especially in young infants. In general, most of the recent work on N. meningitidis focuses on potential antigens and their functions, immunogenicity, and pathogenicity mechanisms. Very little work has been carried out on Neisseria primary metabolism over the past 25 years. 相似文献6.
Eoghan M Cunnane John JE Mulvihill Hilary E Barrett Michael T Walsh 《Biomedical engineering online》2015,14(Z1):S7
Background
Due to the limited number of experimental studies that mechanically characterise human atherosclerotic plaque tissue from the femoral arteries, a recent trend has emerged in current literature whereby one set of material data based on aortic plaque tissue is employed to numerically represent diseased femoral artery tissue. This study aims to generate novel vessel-appropriate material models for femoral plaque tissue and assess the influence of using material models based on experimental data generated from aortic plaque testing to represent diseased femoral arterial tissue.Methods
Novel material models based on experimental data generated from testing of atherosclerotic femoral artery tissue are developed and a computational analysis of the revascularisation of a quarter model idealised diseased femoral artery from a 90% diameter stenosis to a 10% diameter stenosis is performed using these novel material models. The simulation is also performed using material models based on experimental data obtained from aortic plaque testing in order to examine the effect of employing vessel appropriate material models versus those currently employed in literature to represent femoral plaque tissue.Results
Simulations that employ material models based on atherosclerotic aortic tissue exhibit much higher maximum principal stresses within the plaque than simulations that employ material models based on atherosclerotic femoral tissue. Specifically, employing a material model based on calcified aortic tissue, instead of one based on heavily calcified femoral tissue, to represent diseased femoral arterial vessels results in a 487 fold increase in maximum principal stress within the plaque at a depth of 0.8 mm from the lumen.Conclusions
Large differences are induced on numerical results as a consequence of employing material models based on aortic plaque, in place of material models based on femoral plaque, to represent a diseased femoral vessel. Due to these large discrepancies, future studies should seek to employ vessel-appropriate material models to simulate the response of diseased femoral tissue in order to obtain the most accurate numerical results.7.
Background
Representation of independent biophysical sources using Fourier analysis can be inefficient because the basis is sinusoidal and general. When complex fractionated atrial electrograms (CFAE) are acquired during atrial fibrillation (AF), the electrogram morphology depends on the mix of distinct nonsinusoidal generators. Identification of these generators using efficient methods of representation and comparison would be useful for targeting catheter ablation sites to prevent arrhythmia reinduction.Method
A data-driven basis and transform is described which utilizes the ensemble average of signal segments to identify and distinguish CFAE morphologic components and frequencies. Calculation of the dominant frequency (DF) of actual CFAE, and identification of simulated independent generator frequencies and morphologies embedded in CFAE, is done using a total of 216 recordings from 10 paroxysmal and 10 persistent AF patients. The transform is tested versus Fourier analysis to detect spectral components in the presence of phase noise and interference. Correspondence is shown between ensemble basis vectors of highest power and corresponding synthetic drivers embedded in CFAE.Results
The ensemble basis is orthogonal, and efficient for representation of CFAE components as compared with Fourier analysis (p ≤ 0.002). When three synthetic drivers with additive phase noise and interference were decomposed, the top three peaks in the ensemble power spectrum corresponded to the driver frequencies more closely as compared with top Fourier power spectrum peaks (p ≤ 0.005). The synthesized drivers with phase noise and interference were extractable from their corresponding ensemble basis with a mean error of less than 10%.Conclusions
The new transform is able to efficiently identify CFAE features using DF calculation and by discerning morphologic differences. Unlike the Fourier transform method, it does not distort CFAE signals prior to analysis, and is relatively robust to jitter in periodic events. Thus the ensemble method can provide a useful alternative for quantitative characterization of CFAE during clinical study. 相似文献8.
9.
Welch M Mikkelsen H Swatton JE Smith D Thomas GL Glansdorp FG Spring DR 《Molecular bioSystems》2005,1(3):196-202
Over the last decade or so, a wealth of research has established that bacteria communicate with one another using small molecules. These signals enable the individuals in a population to coordinate their behaviour. In the case of pathogens, this behaviour may include decisions such as when to attack a host organism or form a biofilm. Consequently, such signalling systems are excellent targets for the development of new antibacterial therapies. In this review, we assess how Gram-negative bacteria use small molecules for cell-cell communication, and discuss the main approaches that have been developed to interfere with it. 相似文献
10.
M Matsuda A Tazumi S Kagawa T Sekizuka O Murayama JE Moore BC Millar 《BMC veterinary research》2006,2(1):1-4