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131.
Rodal AA Kozubowski L Goode BL Drubin DG Hartwig JH 《Molecular biology of the cell》2005,16(1):372-384
Budding yeast has been a powerful model organism for studies of the roles of actin in endocytosis and septins in cell division and in signaling. However, the depth of mechanistic understanding that can be obtained from such studies has been severely hindered by a lack of ultrastructural information about how actin and septins are organized at the cell cortex. To address this problem, we developed rapid-freeze and deep-etch techniques to image the yeast cell cortex in spheroplasted cells at high resolution. The cortical actin cytoskeleton assembles into conical or mound-like structures composed of short, cross-linked filaments. The Arp2/3 complex localizes near the apex of these structures, suggesting that actin patch assembly may be initiated from the apex. Mutants in cortical actin patch components with defined defects in endocytosis disrupted different stages of cortical actin patch assembly. Based on these results, we propose a model for actin function during endocytosis. In addition to actin structures, we found that septin-containing filaments assemble into two kinds of higher order structures at the cell cortex: rings and ordered gauzes. These images provide the first high-resolution views of septin organization in cells. 相似文献
132.
Shoshana Bar-Noy Avital Darmon Hagai Ginsburg Z.Ioav Cabantchik 《生物化学与生物物理学报:生物膜》1984,778(3):612-614
We describe here a new method, based on fluorescent techniques, for the determination of the orientation of membrane protein molecules present in vesicles. The method consists of: (a) attachment of a fluorescein derivative to sugar residues of glycoproteins and glycolipids in the cell membrane, and (b) the use of anti-fluorescein antibody, a highly efficient quencher of fluorescein fluorescence, for the quantitative evaluation of sidedness of transmembrane orientation of protein molecules in vesicles. Since antibody molecules do not permeate membranes, quenching is limited exclusively to sites exposed at the external surface of the vesicles. Addition of antibody to a fluorescently-labeled cell suspension results in a full and immediate quenching of the fluorescent signal. The method is highly sensitive (pM protein concentration), rapid and readily applicable to various vesicle preparations. With this method we assessed the orientation of vesicles derived from red blood cell membranes (ghosts) in isotonic medium and followed their inversion from right-side-out to inside-out orientation upon incubation in alkaline, low ionic strength medium. 相似文献
133.
Comparative evaluation of the larvivorous fish Gambusia affinis and Aphanius dispar as mosquito control agents 总被引:1,自引:1,他引:0
Under laboratory conditions Aphanius was more successful than Gambusia in preying upon the 3rd, 4th and pupal stages of mosquitoes. The reverse was found for the first two instars. However. Aphanius consumed more 2nd instar larvae under the cover of vegetation when larger fish were able to penetrate shallow water and feed on the mosquito larvae.The two species showed a similar prey-size selection except for Aphanius of the medium size (31–35 mm) which ate larger larvae than Gambusia of the same size range.When provided access to the surface, neither fish species showed any adverse effect at oxygen levels as low as 0.5 mg l-1 (6% saturation). When denied access to the surface, both species behaved normally at oxygen levels as low as 1.3 mg l-1 (15% saturation).This study suggests that Gambusia affinis and Aphanius dispar can complement each other as mosquito control agents in different habitat conditions. We suggest that in mosquito infested situation which are characterized by high organic matter and low oxygen levels biological control could best be achieved by introduction of a range of sizes of both fish species. Repeated introductions of the fish, in large enough numbers, may be required for ad-hoc alleviation of a mosquito problem. Best results are thus to be expected in relatively small water bodies such as oxidation ponds. 相似文献
134.
Guy Bloch Avital Meshi 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2007,193(2):181-199
Octopamine (OA) and juvenile hormone (JH) are implicated in the regulation of age-based division of labor in the honeybee,
Apis mellifera. We tested the hypothesis that these two neuroendocrine signals influence task-associated plasticity in circadian and diurnal
rhythms, and in brain expression of the clock gene period (per). Treatment with OA, OA antagonist (epinastine), or both, did not affect the age at onset of circadian rhythmicity or the
free running period in constant darkness (DD). Young bees orally treated with OA in light–dark (LD) illumination regime for
6 days followed by DD showed reduced alpha (the period between the daily onset and offset of activity) during the first 4 days
in LD and the first 4 days in DD. Oral treatment with OA, epinastine, or both, but not manipulations of JH levels, caused
increased average daily levels and aberrant patterns of brain per mRNA oscillation in young bees. These results suggest that OA and JH do not influence the development or function of the
central pacemaker but rather that OA influences the brain expression of a clock gene and characteristics of locomotor behavior
that are not thought to be under direct control of the circadian pacemaker.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
135.
Sadot A Fisher J Barak D Admanit Y Stern MJ Hubbard EJ Harel D 《IEEE/ACM transactions on computational biology and bioinformatics / IEEE, ACM》2008,5(2):223-234
The last several decades have witnessed a vast accumulation of biological data and data analysis. Many of these data sets represent only a small fraction of the system's behavior, making the visualization of full system behavior difficult. A more complete understanding of a biological system is gained when different types of data (and/or conclusions drawn from the data) are integrated into a larger-scale representation or model of the system. Ideally, this type of model is consistent with all available data about the system, and it is then used to generate additional hypotheses to be tested. Computer-based methods intended to formulate models that integrate various events and to test the consistency of these models with respect to the laboratory-based observations on which they are based are potentially very useful. In addition, in contrast to informal models, the consistency of such formal computer-based models with laboratory data can be tested rigorously by methods of formal verification. We combined two formal modeling approaches in computer science that were originally developed for non-biological system design. One is the inter-object approach using the language of live sequence charts (LSCs) with the Play-Engine tool, and the other is the intra-object approach using the language of statecharts and Rhapsody as the tool. Integration is carried out using InterPlay, a simulation engine coordinator. Using these tools, we constructed a combined model comprising three modules. One module represents the early lineage of the somatic gonad of C. elegans in LSCs, while a second more detailed module in statecharts represents an interaction between two cells within this lineage that determine their developmental outcome. Using the advantages of the tools, we created a third module representing a set of key experimental data using LSCs. We tested the combined statechart-LSC model by showing that the simulations were consistent with the set of experimental LSCs. This small-scale modular example demonstrates the potential for using similar approaches for verification by exhaustive testing of models by LSCs. It also shows the advantages of these approaches for modeling biology. 相似文献
136.
Raphael Ber Emanuelle Mamroud Moshe Aftalion Avital Tidhar David Gur Yehuda Flashner Sara Cohen 《Applied microbiology》2003,69(10):5787-5792
Existing media designed for selective isolation of clinically important members of the genus Yersinia were found to be unsatisfactory for the growth and isolation of Yersinia pestis. We report the development of a new selective agar medium (termed BIN) that supports the growth of Y. pestis. The development of the formulation of this medium was based on a fluorescence screening system designed for monitoring bacterial growth on semisolid media, using a green fluorescent protein-expressing strain. High-throughput combinatorial experiments can be conducted for the quantitative evaluation of the effect of different medium components on growth. Generation of fluorescence plots in this system, using microplates, allowed the quantitative evaluation of the growth rate of Y. pestis EV76 cultures in different agar compositions. The final BIN formulation is based on brain heart infusion agar, to which the selective agents irgasan, cholate salts, crystal violet, and nystatin were introduced. It was found that BIN agar is more efficient in supporting colony formation and recovery of Y. pestis than are the conventional semisolid media MacConkey agar and Yersinia-selective agar (cefsulodin-irgasan-novobiocin agar). The advantage of BIN over other media has been also demonstrated in recovering virulent Y. pestis from the mixed bacterial populations found in decaying carcasses of infected mice. The BIN medium is suggested as a selective medium for isolation and recovery of Y. pestis from various backgrounds. 相似文献
137.
The actin cytoskeleton of budding yeast contains an extensive set of actin-associated proteins with conserved mammalian counterparts. For more than 20 years, yeast has been used as a model organism to dissect the in vivo functions of these factors, revealing an intricate web of genetic interactions in the cell. Now, a surge of biochemical reports is defining the physical interactions and activities of these proteins and providing mechanistic insights into their cellular roles. The emerging view is that most actin-associated proteins do not act alone but, rather, associate to form modular protein complexes that regulate actin assembly and organization. 相似文献
138.
Kate Koles Emily M. Messelaar Zachary Feiger Crystal J. Yu C. Andrew Frank Avital A. Rodal 《Molecular biology of the cell》2015,26(18):3275-3288
Membranes form elaborate structures that are highly tailored to their specialized cellular functions, yet the mechanisms by which these structures are shaped remain poorly understood. Here, we show that the conserved membrane-remodeling C-terminal Eps15 Homology Domain (EHD) protein Past1 is required for the normal assembly of the subsynaptic muscle membrane reticulum (SSR) at the Drosophila melanogaster larval neuromuscular junction (NMJ). past1 mutants exhibit altered NMJ morphology, decreased synaptic transmission, reduced glutamate receptor levels, and a deficit in synaptic homeostasis. The membrane-remodeling proteins Amphiphysin and Syndapin colocalize with Past1 in distinct SSR subdomains and collapse into Amphiphysin-dependent membrane nodules in the SSR of past1 mutants. Our results suggest a mechanism by which the coordinated actions of multiple lipid-binding proteins lead to the elaboration of increasing layers of the SSR and uncover new roles for an EHD protein at synapses. 相似文献
139.
140.
The alanine-serine-cysteine-1 (Asc-1) transporter controls glycine levels in the brain and is required for glycinergic inhibitory transmission 下载免费PDF全文
Hazem Safory Samah Neame Yoav Shulman Salman Zubedat Inna Radzishevsky Dina Rosenberg Hagit Sason Simone Engelender Avi Avital Swen Hülsmann Jackie Schiller Herman Wolosker 《EMBO reports》2015,16(5):590-598
Asc-1 (SLC7A10) is an amino acid transporter whose deletion causes neurological abnormalities and early postnatal death in mice. Using metabolomics and behavioral and electrophysiological methods, we demonstrate that Asc-1 knockout mice display a marked decrease in glycine levels in the brain and spinal cord along with impairment of glycinergic inhibitory transmission, and a hyperekplexia-like phenotype that is rescued by replenishing brain glycine. Asc-1 works as a glycine and L-serine transporter, and its transport activity is required for the subsequent conversion of L-serine into glycine in vivo. Asc-1 is a novel regulator of glycine metabolism and a candidate for hyperekplexia disorders. 相似文献