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101.
Abishek Muralidhar Phil M. Novis Paul A. Broady David A. Collings Ashley Garrill 《Journal of phycology》2013,49(5):967-978
Turgor regulation is the process by which walled organisms alter their internal osmotic potential to adapt to osmotic changes in the environment. Apart from a few studies on freshwater oomycetes, the ability of stramenopiles to turgor regulate has not been investigated. In this study, turgor regulation and growth were compared in two species of the stramenopile alga Vaucheria, Vaucheria erythrospora isolated from an estuarine habitat, and Vaucheria repens isolated from a freshwater habitat. Species were identified using their rbcL sequences and respective morphologies. Using a single cell pressure probe to directly measure turgor in Vaucheria after hyperosmotic shock, V. erythrospora was found to recover turgor after a larger shock than V. repens. Threshold shock values for this ability were >0.5 MPa for V. erythrospora and <0.5 MPa for V. repens. Recovery was more rapid in V. erythrospora than V. repens after comparable shocks. Turgor recovery in V. erythrospora was inhibited by Gd3+ and TEA, suggesting a role for mechanosensitive channels, nonselective cation channels, and K+ channels in the process. Growth studies showed that V. erythrospora was able to grow over a wider range of NaCl concentrations. These responses may underlie the ability of V. erythrospora to survive in an estuarine habitat and restrict V. repens to freshwater. The fact that both species can turgor regulate may indicate a fundamental difference between members of the Stramenopila, as research to date on oomycetes suggests they are unable to turgor regulate. 相似文献
102.
Jessica S. Ross Wei Hu Bess Rosen Ashley J. Snider Lina M. Obeid L. Ashley Cowart 《The Journal of biological chemistry》2013,288(31):22193-22206
We previously demonstrated that sphingosine kinase 1 (Sphk1) expression and activity are up-regulated by exogenous palmitate (PAL) in a skeletal muscle model system and in diet-induced obesity in mice; however, potential functions and in vivo relevance of this have not been addressed. Here, we aimed to determine the mechanism by which PAL regulates SphK1 in muscle, and to determine potential roles for its product, sphingosine-1-phosphate (S1P), in muscle biology in the context of obesity. Cloning and analysis of the mouse Sphk1 promoter revealed a peroxisome proliferator-activated receptor (PPAR) α cis-element that mediated activation of a reporter under control of the Sphk1 promoter; direct interaction of PPARα was demonstrated by chromatin immunoprecipitation. PAL treatment induced the proinflammatory cytokine interleukin (IL)-6 in a manner dependent on SphK1, and this was attenuated by inhibition of the sphingosine-1-phosphate receptor 3 (S1PR3). Diet-induced obesity in mice demonstrated that IL-6 expression in muscle, but not adipose tissue, increased in obesity, but this was attenuated in Sphk1−/− mice. Moreover, plasma IL-6 levels were significantly decreased in obese Sphk1−/− mice relative to obese wild type mice, and muscle, but not adipose tissue IL-6 signaling was activated. These data indicate that PPARα regulates Sphk1 expression in the context of fatty acid oversupply and links PAL to muscle IL-6 production. Moreover, this function of SphK1 in diet-induced obesity suggests a potential role for SphK1 in obesity-associated pathological outcomes. 相似文献
103.
Ryan P. P. Shugg Ashley Thomson Natsuko Tanabe Adam Kashishian Bart H. Steiner Kamal D. Puri Alexey Pereverzev Brian J. Lannutti Frank R. Jirik S. Jeffrey Dixon Stephen M. Sims 《The Journal of biological chemistry》2013,288(49):35346-35357
Phosphatidylinositol 3-kinases (PI3K) participate in numerous signaling pathways, and control distinct biological functions. Studies using pan-PI3K inhibitors suggest roles for PI3K in osteoclasts, but little is known about specific PI3K isoforms in these cells. Our objective was to determine effects of isoform-selective PI3K inhibitors on osteoclasts. The following inhibitors were investigated (targets in parentheses): wortmannin and (pan-p110), PIK75 (α), GDC0941 (α, δ), TGX221 (β), AS252424 (γ), and IC87114 (δ). In addition, we characterized a new potent and selective PI3Kδ inhibitor, GS-9820, and explored roles of PI3K isoforms in regulating osteoclast function. Osteoclasts were isolated from long bones of neonatal rats and rabbits. Wortmannin, LY294002, GDC0941, IC87114, and GS-9820 induced a dramatic retraction of osteoclasts within 15–20 min to 65–75% of the initial area. In contrast, there was no significant retraction in response to vehicle, PIK75, TGX221, or AS252424. Moreover, wortmannin and GS-9820, but not PIK75 or TGX221, disrupted actin belts. We examined effects of PI3K inhibitors on osteoclast survival. Whereas PIK75, TGX221, and GS-9820 had no significant effect on basal survival, all blocked RANKL-stimulated survival. When studied on resorbable substrates, osteoclastic resorption was suppressed by wortmannin and inhibitors of PI3Kβ and PI3Kδ, but not other isoforms. These data are consistent with a critical role for PI3Kδ in regulating osteoclast cytoskeleton and resorptive activity. In contrast, multiple PI3K isoforms contribute to the control of osteoclast survival. Thus, the PI3Kδ isoform, which is predominantly expressed in cells of hematopoietic origin, is an attractive target for anti-resorptive therapeutics. LY294002相似文献
104.
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106.
Sangshin Park Sarah Navratil Ashley Gregory Arin Bauer Indumathi Srinath Mikyoung Jun Barbara Szonyi Kendra Nightingale Juan Anciso Renata Ivanek 《Applied and environmental microbiology》2013,79(14):4347-4358
The objective of this study was to determine the effects of farm management and environmental factors on preharvest spinach contamination with generic Escherichia coli as an indicator of fecal contamination. A repeated cross-sectional study was conducted by visiting spinach farms up to four times per growing season over a period of 2 years (2010 to 2011). Spinach samples (n = 955) were collected from 12 spinach farms in Colorado and Texas as representative states of the Western and Southwestern United States, respectively. During each farm visit, farmers were surveyed about farm-related management and environmental factors using a questionnaire. Associations between the prevalence of generic E. coli in spinach and farm-related factors were assessed by using a multivariable logistic regression model including random effects for farm and farm visit. Overall, 6.6% of spinach samples were positive for generic E. coli. Significant risk factors for spinach contamination with generic E. coli were the proximity (within 10 miles) of a poultry farm, the use of pond water for irrigation, a >66-day period since the planting of spinach, farming on fields previously used for grazing, the production of hay before spinach planting, and the farm location in the Southwestern United States. Contamination with generic E. coli was significantly reduced with an irrigation lapse time of >5 days as well as by several factors related to field workers, including the use of portable toilets, training to use portable toilets, and the use of hand-washing stations. To our knowledge, this is the first report of an association between field workers'' personal hygiene and produce contamination with generic E. coli at the preharvest level. Collectively, our findings support that practice of good personal hygiene and other good farm management practices may reduce produce contamination with generic E. coli at the preharvest level. 相似文献
107.
Ashley Slocum Mike Burnham Paul Genest Adith Venkiteshwaran Dayue Chen Joseph Hughes 《Biotechnology and bioengineering》2013,110(1):229-239
Virus‐removal filtration technology is commonly used in the manufacturing process for biologics to remove potential viral contaminants. Virus‐removal filters designed for retaining parvovirus, one of the smallest mammalian viruses, are considered an industry standard as they can effectively remove broad ranges of viruses. It has long been observed that the performance of virus filters can be influenced by virus preparations used in the laboratory scale studies (PDA, 2010 ). However, it remains unclear exactly what quality attributes of virus preparations are critical or indicative of virus filter performance as measured by effectiveness of virus removal and filter capacity consistency. In an attempt to better understand the relationship between virus preparation and virus filter performance, we have systematically prepared and analyzed different grades of parvovirus with different purity levels and compared their performance profiles on Viresolve® Pro parvovirus filters using four different molecules. Virus preparations used in the studies were characterized using various methods to measure DNA and protein content as well as the hydrodynamic diameter of virus particles. Our results indicate that the performance of Viresolve® Pro filters can be significantly impacted depending on the purity of the virus preparations used in the spike and recovery studies. More importantly, we have demonstrated that the purity of virus preparations is directly correlated to the measurable biochemical and biophysical properties of the virus preparations such as DNA and protein content and monodispersal status, thus making it possible to significantly improve the consistency and predictability of the virus filter performance during process step validations. Biotechnol. Bioeng. 2013; 110: 229–239. © 2012 Wiley Periodicals, Inc. 相似文献
108.
Elizabeth Gibbons Katalyn R. Pickett Michael C. Streeter Ashley O. Warcup Jennifer Nelson Allan M. Judd John D. Bell 《生物化学与生物物理学报:生物膜》2013,1828(2):887-895
Secretory phospholipase A2 exhibits much greater activity toward apoptotic versus healthy cells. Various plasma membrane changes responsible for this phenomenon have been proposed, including biophysical alterations described as “membrane fluidity” and “order.” Understanding of these membrane perturbations was refined by applying studies with model membranes to fluorescence measurements during thapsigargin-induced apoptosis of S49 cells using probes specific for the plasma membrane: Patman and trimethylammonium-diphenylhexatriene. Alterations in emission properties of these probes corresponded with enhanced susceptibility of the cells to hydrolysis by secretory phospholipase A2. By applying a quantitative model, additional information was extracted from the kinetics of Patman equilibration with the membrane. Taken together, these data suggested that the phospholipids of apoptotic membranes display greater spacing between adjacent headgroups, reduced interactions between neighboring lipid tails, and increased penetration of water among the heads. The phase transition of artificial bilayers was used to calibrate quantitatively the relationship between probe fluorescence and the energy of interlipid interactions. This analysis was applied to results from apoptotic cells to estimate the frequency with which phospholipids protrude sufficiently at the membrane surface to enter the enzyme's active site. The data suggested that this frequency increases 50–100-fold as membranes become susceptible to hydrolysis during apoptosis. 相似文献
109.
While there is little doubt that risk-taking is generally more prevalent during adolescence than before or after, the underlying causes of this pattern of age differences have long been investigated and debated. One longstanding popular notion is the belief that risky and reckless behavior in adolescence is tied to the hormonal changes of puberty. However, the interactions between pubertal maturation and adolescent decision making remain largely understudied. In the current review, we discuss changes in decision making during adolescence, focusing on the asynchronous development of the affective, reward-focused processing system and the deliberative, reasoned processing system. As discussed, differential maturation in the structure and function of brain systems associated with these systems leaves adolescents particularly vulnerable to socio-emotional influences and risk-taking behaviors. We argue that this asynchrony may be partially linked to pubertal influences on development and specifically on the maturation of the affective, reward-focused processing system. 相似文献
110.
Roland Beckmann Ashley M. Toye Jonathan S. Smythe David J. Anstee Michael J.A. Tanner 《Molecular membrane biology》2013,30(3):187-200
Two isoforms of the band 3 anion exchanger are expressed in mammalian cells, a 911 residue protein (B3) in red cells, and a truncated protein (KB3) in the f -intercalated cells of the kidney. Mutants of both isoforms are known to be associated with human disease, and mistargeting of the mutated proteins has been suggested as the mechanism of pathogenesis in several cases but has been difficult to prove. The present study demonstrates the feasibility of using confocal microscopy for investigating the targeting of homozygous and heterozygous B3 and KB3 mutants. K562 erythroleukemia cells offer several advantages for the stable expression of B3, but have not previously been used for its visualization. A wide range of cell attachment factors, growth conditions, fixation reagents and primary antibodies were investigated to enable imaging of B3 and endogenous GPA by immunofluorescence confocal microscopy in stable K562/B3 clones. B3 co-localized with GPA at the cell surface and also in an intracellular compartment. Functional cell surface expression of KB3 in stable K562 clones was also obtained. Importantly, both B3 and KB3 could be expressed as stable fusion proteins tagged with green fluorescent protein (GFP) in K562 cells, and it was demonstrated that N-terminal GFP-tagging does not affect the targeting or chloride transport properties of B3 or KB3. The use of GFP as well as double-labelling methods developed for immunostaining will be invaluable for investigating the interactions of band 3 with itself and other proteins during its trafficking in erythroid and kidney cells. This will help elucidate how band 3 mutations can cause human diseases such as hereditary spherocytosis and distal renal tubular acidosis. 相似文献