全文获取类型
收费全文 | 5388篇 |
免费 | 585篇 |
国内免费 | 3篇 |
出版年
2021年 | 79篇 |
2020年 | 50篇 |
2019年 | 58篇 |
2018年 | 75篇 |
2017年 | 65篇 |
2016年 | 116篇 |
2015年 | 135篇 |
2014年 | 177篇 |
2013年 | 207篇 |
2012年 | 282篇 |
2011年 | 248篇 |
2010年 | 183篇 |
2009年 | 144篇 |
2008年 | 195篇 |
2007年 | 230篇 |
2006年 | 206篇 |
2005年 | 200篇 |
2004年 | 201篇 |
2003年 | 174篇 |
2002年 | 163篇 |
2001年 | 147篇 |
2000年 | 172篇 |
1999年 | 128篇 |
1998年 | 69篇 |
1997年 | 54篇 |
1996年 | 51篇 |
1995年 | 49篇 |
1994年 | 45篇 |
1992年 | 91篇 |
1991年 | 71篇 |
1990年 | 79篇 |
1989年 | 103篇 |
1988年 | 70篇 |
1987年 | 70篇 |
1986年 | 77篇 |
1985年 | 79篇 |
1984年 | 72篇 |
1983年 | 65篇 |
1982年 | 49篇 |
1980年 | 48篇 |
1979年 | 59篇 |
1978年 | 46篇 |
1977年 | 44篇 |
1976年 | 46篇 |
1975年 | 54篇 |
1974年 | 65篇 |
1973年 | 55篇 |
1972年 | 60篇 |
1971年 | 54篇 |
1968年 | 47篇 |
排序方式: 共有5976条查询结果,搜索用时 796 毫秒
991.
Desmond MJ Lee D Fraser SA Katerelos M Gleich K Martinello P Li YQ Thomas MC Michelucci R Cole AJ Saftig P Schwake M Stapleton D Berkovic SF Power DA 《American journal of physiology. Renal physiology》2011,300(6):F1437-F1447
Deficiency of the intrinsic lysosomal protein human scavenger receptor class B, member 2 (SCARB2; Limp-2 in mice) causes collapsing focal and segmental glomerular sclerosis (FSGS) and myoclonic epilepsy in humans, but patients with no apparent kidney damage have recently been described. We now demonstrate that these patients can develop tubular proteinuria. To determine the mechanism, mice deficient in Limp-2, the murine homolog of SCARB2, were studied. Most low-molecular-weight proteins filtered by the glomerulus are removed in the proximal convoluted tubule (PCT) by megalin/cubilin-dependent receptor-mediated endocytosis. Expression of megalin and cubilin was unchanged in Limp-2(-/-) mice, however, and the initial uptake of injected Alexa Fluor 555-conjugated bovine serum albumin (Alexa-BSA) was similar to wild-type mice, indicating that megalin/cubilin-dependent, receptor-mediated endocytosis was unaffected. There was a defect in proteolysis of reabsorbed proteins in the Limp-2(-/-) mice, demonstrated by the persistence of Alexa-BSA in the PCT compared with controls. This was associated with the failure of the lysosomal protease cathepsin B to colocalize with Alexa-BSA and endogenous retinol-binding protein in kidneys from Limp-2(-/-) mice. The data suggest that tubular proteinuria in Limp-2(-/-) mice is due to failure of endosomes containing reabsorbed proteins to fuse with lysosomes in the proximal tubule of the kidney. Failure of proteolysis is a novel mechanism for tubular proteinuria. 相似文献
992.
Dunn KW Kamocka MM McDonald JH 《American journal of physiology. Cell physiology》2011,300(4):C723-C742
Fluorescence microscopy is one of the most powerful tools for elucidating the cellular functions of proteins and other molecules. In many cases, the function of a molecule can be inferred from its association with specific intracellular compartments or molecular complexes, which is typically determined by comparing the distribution of a fluorescently labeled version of the molecule with that of a second, complementarily labeled probe. Although arguably the most common application of fluorescence microscopy in biomedical research, studies evaluating the "colocalization" of two probes are seldom quantified, despite a diversity of image analysis tools that have been specifically developed for that purpose. Here we provide a guide to analyzing colocalization in cell biology studies, emphasizing practical application of quantitative tools that are now widely available in commercial and free image analysis software. 相似文献
993.
994.
Tavakkoli E Fatehi F Coventry S Rengasamy P McDonald GK 《Journal of experimental botany》2011,62(6):2189-2203
Soil salinity affects large areas of the world's cultivated land, causing significant reductions in crop yield. Despite the fact that most plants accumulate both sodium (Na(+)) and chloride (Cl(-)) ions in high concentrations in their shoot tissues when grown in saline soils, most research on salt tolerance in annual plants has focused on the toxic effects of Na(+) accumulation. It has previously been suggested that Cl(-) toxicity may also be an important cause of growth reduction in barley plants. Here, the extent to which specific ion toxicities of Na(+) and Cl(-) reduce the growth of barley grown in saline soils is shown under varying salinity treatments using four barley genotypes differing in their salt tolerance in solution and soil-based systems. High Na(+), Cl(-), and NaCl separately reduced the growth of barley, however, the reductions in growth and photosynthesis were greatest under NaCl stress and were mainly additive of the effects of Na(+) and Cl(-) stress. The results demonstrated that Na(+) and Cl(-) exclusion among barley genotypes are independent mechanisms and different genotypes expressed different combinations of the two mechanisms. High concentrations of Na(+) reduced K(+) and Ca(2+) uptake and reduced photosynthesis mainly by reducing stomatal conductance. By comparison, high Cl(-) concentration reduced photosynthetic capacity due to non-stomatal effects: there was chlorophyll degradation, and a reduction in the actual quantum yield of PSII electron transport which was associated with both photochemical quenching and the efficiency of excitation energy capture. The results also showed that there are fundamental differences in salinity responses between soil and solution culture, and that the importance of the different mechanisms of salt damage varies according to the system under which the plants were grown. 相似文献
995.
Rainbow DB Moule C Fraser HI Clark J Howlett SK Burren O Christensen M Moody V Steward CA Mohammed JP Fusakio ME Masteller EL Finger EB Houchins JP Naf D Koentgen F Ridgway WM Todd JA Bluestone JA Peterson LB Mattner J Wicker LS 《Journal of immunology (Baltimore, Md. : 1950)》2011,187(1):325-336
We have previously proposed that sequence variation of the CD101 gene between NOD and C57BL/6 mice accounts for the protection from type 1 diabetes (T1D) provided by the insulin-dependent diabetes susceptibility region 10 (Idd10), a <1 Mb region on mouse chromosome 3. In this study, we provide further support for the hypothesis that Cd101 is Idd10 using haplotype and expression analyses of novel Idd10 congenic strains coupled to the development of a CD101 knockout mouse. Susceptibility to T1D was correlated with genotype-dependent CD101 expression on multiple cell subsets, including Foxp3(+) regulatory CD4(+) T cells, CD11c(+) dendritic cells, and Gr1(+) myeloid cells. The correlation of CD101 expression on immune cells from four independent Idd10 haplotypes with the development of T1D supports the identity of Cd101 as Idd10. Because CD101 has been associated with regulatory T and Ag presentation cell functions, our results provide a further link between immune regulation and susceptibility to T1D. 相似文献
996.
Daniel H. Catlin Joy H. Felio James D. Fraser 《The Journal of wildlife management》2011,75(2):458-462
We studied the effect of great-horned owl (Bubo virginianus) removal on piping plover (Charadrius melodus) hatchling survival on Missouri River sandbars (2008–2009). Owl removal increased daily survival of piping plover chicks in 2008 (β = 2.03, 95% CI: 0.04–4.02), but this effect decreased with increasing age of the chick (β = −0.42, 95% CI: −0.81 to −0.03). Results for 2009 were similar in direction but not significant. Survival was higher in 2008 than in 2009, regardless of owl capture, indicating that even if owl capture consistently were effective at increasing survival, overall survival resulting from trapping may vary annually. Owl trapping was a successful means to raise chick survival on the Missouri River in ≥1 year and could be used at other sites experiencing depressed chick survival due to avian predators. © 2011 The Wildlife Society. 相似文献
997.
Crouch E Nikolaidis N McCormack FX McDonald B Allen K Rynkiewicz MJ Cafarella TM White M Lewnard K Leymarie N Zaia J Seaton BA Hartshorn KL 《The Journal of biological chemistry》2011,286(47):40681-40692
The recognition of influenza A virus (IAV) by surfactant protein D (SP-D) is mediated by interactions between the SP-D carbohydrate recognition domains (CRD) and glycans displayed on envelope glycoproteins. Although native human SP-D shows potent antiviral and aggregating activity, trimeric recombinant neck+CRDs (NCRDs) show little or no capacity to influence IAV infection. A mutant trimeric NCRD, D325A/R343V, showed marked hemagglutination inhibition and viral neutralization, with viral aggregation and aggregation-dependent viral uptake by neutrophils. D325A/R343V exhibited glucose-sensitive binding to Phil82 hemagglutinin trimer (HA) by surface plasmon resonance. By contrast, there was very low binding to the HA trimer from another virus (PR8) that lacks glycans on the HA head. Mass spectrometry demonstrated the presence of high mannose glycans on the Phil82 HA at positions known to contribute to IAV binding. Molecular modeling predicted an enhanced capacity for bridging interactions between HA glycans and D325A/R343V. Finally, the trimeric D325A/R343V NCRD decreased morbidity and increased viral clearance in a murine model of IAV infection using a reassortant A/WSN/33 virus with a more heavily glycosylated HA. The combined data support a model in which altered binding by a truncated mutant SP-D to IAV HA glycans facilitates viral aggregation, leading to significant viral neutralization in vitro and in vivo. These studies demonstrate the potential utility of homology modeling and protein structure analysis for engineering effective collectin antivirals as in vivo therapeutics. 相似文献
998.
Human ether-a-go-go-related gene product (HERG) is a cardiac potassium channel commonly implicated in the pathogenesis of the long QT syndrome, type 2 (LQT2). LQT2 mutations typically have incomplete penetrance and affect individuals at various stages of their lives; this may mirror variations in intracellular signaling and HERG regulation. Previous work showed that sustained protein kinase A (PKA) activity augments HERG protein abundance by a mechanism that includes enhanced protein translation. To investigate the subcellular site of this regulation, we generated site-specific probes to the cytoplasmic surface of the endoplasmic reticulum (ER), the presumed locale of channel synthesis. Real-time FRET-based indicators demonstrated both cAMP and PKA activity at the ER. A PKA inhibitor targeted to the ER surface (termed p4PKIg) completely abolished PKA-mediated augmentation of HERG in HEK293 cells as well as rat neonatal cardiomyocytes. Immunofluorescence co-localization, targeted FRET-based PKA biosensors, phospho-specific antibodies, and in vivo phosphorylation experiments confirmed that p4PKIg is preferentially active at the ER surface rather than the plasma membrane. Rerouting this inhibitor to the outer mitochondrial membrane diminishes its ability to block cAMP-dependent HERG induction. Our results support a model where PKA-dependent regulation of HERG synthesis occurs at the ER surface. Furthermore, reagents generated for this study provide novel experimental tools to probe compartmentalized cAMP/PKA signaling within cells. 相似文献
999.
Wang Y Keck ZY Saha A Xia J Conrad F Lou J Eckart M Marks JD Foung SK 《The Journal of biological chemistry》2011,286(51):44218-44233
A potent neutralizing antibody to a conserved hepatitis C virus (HCV) epitope might overcome its extreme variability, allowing immunotherapy. The human monoclonal antibody HC-1 recognizes a conformational epitope on the HCV E2 glycoprotein. Previous studies showed that HC-1 neutralizes most HCV genotypes but has modest potency. To improve neutralization, we affinity-matured HC-1 by constructing a library of yeast-displayed HC-1 single chain Fv (scFv) mutants, using for selection an E2 antigen from one of the poorly neutralized HCVpp. We developed an approach by parallel mutagenesis of the heavy chain variable (VH) and κ-chain variable (Vk) genes separately, then combining the optimized VH and Vk mutants. This resulted in the generation of HC-1-related scFv variants exhibiting improved affinities. The best scFv variant had a 92-fold improved affinity. After conversion to IgG1, some of the antibodies exhibited a 30-fold improvement in neutralization activity. Both surface plasmon resonance and solution kinetic exclusion analysis showed that the increase in affinity was largely due to a lowering of the dissociation rate constant, Koff. Neutralization against a panel of HCV pseudoparticles and infectious 2a HCV virus improved with the affinity-matured IgG1 antibodies. Interestingly, some of these antibodies neutralized a viral isolate that was not neutralized by wild-type HC-1. Moreover, propagating 2a HCVcc under the selective pressure of WT HC-1 or affinity-matured HC-1 antibodies yielded no viral escape mutants and, with the affinity-matured IgG1, needed 100-fold less antibody to achieve complete virus elimination. Taken together, these findings suggest that affinity-matured HC-1 antibodies are excellent candidates for therapeutic development. 相似文献
1000.