全文获取类型
收费全文 | 1577篇 |
免费 | 110篇 |
国内免费 | 2篇 |
出版年
2023年 | 7篇 |
2022年 | 15篇 |
2021年 | 46篇 |
2020年 | 23篇 |
2019年 | 35篇 |
2018年 | 40篇 |
2017年 | 39篇 |
2016年 | 71篇 |
2015年 | 67篇 |
2014年 | 85篇 |
2013年 | 116篇 |
2012年 | 110篇 |
2011年 | 161篇 |
2010年 | 58篇 |
2009年 | 74篇 |
2008年 | 101篇 |
2007年 | 87篇 |
2006年 | 75篇 |
2005年 | 71篇 |
2004年 | 55篇 |
2003年 | 51篇 |
2002年 | 54篇 |
2001年 | 22篇 |
2000年 | 15篇 |
1999年 | 13篇 |
1998年 | 15篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 9篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 10篇 |
1976年 | 4篇 |
1975年 | 9篇 |
1974年 | 13篇 |
1973年 | 7篇 |
1971年 | 4篇 |
排序方式: 共有1689条查询结果,搜索用时 21 毫秒
991.
Barbara Royer Karim Hnia Christos Gavriilidis Hélène Tronchère Valérie Tosch Jocelyn Laporte 《EMBO reports》2013,14(10):907-915
Myotubularin (MTM1) and amphiphysin 2 (BIN1) are two proteins mutated in different forms of centronuclear myopathy, but the functional and pathological relationship between these two proteins was unknown. Here, we identified MTM1 as a novel binding partner of BIN1, both in vitro and endogenously in skeletal muscle. Moreover, MTM1 enhances BIN1‐mediated membrane tubulation, depending on binding and phosphoinositide phosphatase activity. BIN1 patient mutations induce a conformational change in BIN1 and alter its binding and regulation by MTM1. In conclusion, we identified the first molecular and functional link between MTM1 and BIN1, supporting a common pathological mechanism in different forms of centronuclear myopathy. 相似文献
992.
Telomere dysfunction is linked with genome instability and premature aging. Roles for sirtuin proteins at telomeres are thought to promote lifespan in yeast and mammals. However, replicative lifespan of the budding yeast Saccharomyces cerevisiae shortens upon deletion of Rif1, a protein that limits the recruitment of the sirtuin histone deacetylase Sir2 to telomeres. Here we show that Rif1 maintains replicative lifespan by ultimately stabilizing another age‐related chromosomal domain harboring the ribosomal DNA (rDNA) repeats. Deletion of Rif1 increases Sir2 localization to telomeres and the silent mating‐type loci, while releasing a pool of the histone deacetylase from the intergenic spacer 1 (IGS1) of rDNA. This is accompanied by a disruption of IGS1 silent chromatin assembly and increases in aberrant recombination within rDNA repeats. Lifespan defects linked with Rif1 deletion are abolished if rDNA repeats are forcibly stabilized via deletion of the replication fork‐blocking protein Fob1. In addition, Sir2 overexpression prevents Rif1 deletion from disrupting Sir2 at IGS1 and shortening lifespan. Moreover, subjecting cells lacking Rif1 to caloric restriction increases IGS1 histone deacetylation and lifespan, while uncovering novel genetic interactions between RIF1 and SIR2. Our data indicate that Rif1 maintains lifespan‐sustaining levels of Sir2 at rDNA by preventing excessive recruitment of the histone deacetylase to telomeric and silent mating‐type loci. As sirtuin histone deacetylases, such as Sir2 or mammalian SIRT6, each operate at multiple age‐related loci, we propose that factors limiting the localization of sirtuins to certain age‐related loci can promote lifespan‐sustaining roles of these sirtuins elsewhere in the genome. 相似文献
993.
Anna Giulia Balducci Enrico Magosso Gaia Colombo Fabio Sonvico Nurzalina Abdul Karim Khan Kah Hay Yuen Ruggero Bettini Paolo Colombo Alessandra Rossi 《AAPS PharmSciTech》2013,14(3):911-918
Artemisinin, a poorly water-soluble antimalarial drug, presents a low and erratic bioavailability upon oral administration. The aim of this work was to study an agglomerated powder dosage form for oral administration of artemisinin based on the artemisinin/β-cyclodextrin primary microparticles. These primary microparticles were prepared by spray-drying a water–methanol solution of artemisinin/β-cyclodextrin. β-Cyclodextrin in spray-dried microparticles increased artemisinin water apparent solubility approximately sixfold. The thermal analysis evidenced a reduction in the enthalpy value associated with drug melting, due to the decrease in drug crystallinity. The latter was also evidenced by powder X-ray diffraction analysis, while 13C-NMR analysis indicated the partial complexation with β-cyclodextrin. Agglomerates obtained by sieve vibration of spray-dried artemisinin/β-cyclodextrin primary microparticles exhibited free flowing and close packing properties compared with the non-flowing microparticulate powder. The in vitro dissolution rate determination of artemisinin from the agglomerates showed that in 10 min about 70% of drug was released from the agglomerates, whereas less than 10% of artemisinin was dissolved from raw material powder. Oral administration of agglomerates in rats yielded higher artemisinin plasma levels compared to those of pure drug. In the case of the agglomerated powder, a 3.2-fold increase in drug fraction absorbed was obtained. 相似文献
994.
995.
Karim M ElSawy Chandra S Verma David P Lane Leo SD Caves 《Cell cycle (Georgetown, Tex.)》2013,12(24):3727-3735
The stereoselective affinity of small-molecule binding to proteins is typically broadly explained in terms of the thermodynamics of the final bound complex. Using Brownian dynamics simulations, we show that the preferential binding of the MDM2 protein to the geometrical isomers of Nutlin-3, an effective anticancer lead that works by inhibiting the interaction between the proteins p53 and MDM2, can be explained by kinetic arguments related to the formation of the MDM2:Nutlin-3 encounter complex. This is a diffusively bound state that forms prior to the final bound complex. We find that the MDM2 protein stereoselectivity for the Nutlin-3a enantiomer stems largely from the destabilization of the encounter complex of its mirror image enantiomer Nutlin-3b, by the K70 residue that is located away from the binding site. On the other hand, the trans-Nutlin-3a diastereoisomer exhibits a shorter residence time in the vicinity of MDM2 compared with Nutlin-3a due to destabilization of its encounter complex by the collective interaction of pairs of charged residues on either side of the binding site: Glu25 and Lys51 on one side, and Lys94 and Arg97 on the other side. This destabilization is largely due to the electrostatic potential of the trans-Nutlin-3a isomer being largely positive over extended continuous regions around its structure, which are otherwise well-identified into positive and negative regions in the case of the Nutlin-3a isomer. Such rich insight into the binding processes underlying biological selectivity complements the static view derived from the traditional thermodynamic analysis of the final bound complex. This approach, based on an explicit consideration of the dynamics of molecular association, suggests new avenues for kinetics-based anticancer drug development and discovery. 相似文献
996.
Miguel?Lacerda Penny?L?Moore Nobubelo?K?Ngandu Michael?Seaman Elin?S?Gray Ben?Murrell Mohan?Krishnamoorthy Molati?Nonyane Maphuti?Madiga Constantinos?Kurt?Wibmer Daniel?Sheward Robert?T?Bailer Hongmei?Gao Kelli?M?Greene Salim?S?Abdool?Karim John?R?Mascola Bette?TM?Korber David?C?Montefiori Lynn?Morris Carolyn?Williamson Cathal?SeoigheEmail author the CAVD-NSDP Consortium 《Virology journal》2013,10(1):347
Background
Identification of the epitopes targeted by antibodies that can neutralize diverse HIV-1 strains can provide important clues for the design of a preventative vaccine.Methods
We have developed a computational approach that can identify key amino acids within the HIV-1 envelope glycoprotein that influence sensitivity to broadly cross-neutralizing antibodies. Given a sequence alignment and neutralization titers for a panel of viruses, the method works by fitting a phylogenetic model that allows the amino acid frequencies at each site to depend on neutralization sensitivities. Sites at which viral evolution influences neutralization sensitivity were identified using Bayes factors (BFs) to compare the fit of this model to that of a null model in which sequences evolved independently of antibody sensitivity. Conformational epitopes were identified with a Metropolis algorithm that searched for a cluster of sites with large Bayes factors on the tertiary structure of the viral envelope.Results
We applied our method to ID50 neutralization data generated from seven HIV-1 subtype C serum samples with neutralization breadth that had been tested against a multi-clade panel of 225 pseudoviruses for which envelope sequences were also available. For each sample, between two and four sites were identified that were strongly associated with neutralization sensitivity (2ln(BF)?>?6), a subset of which were experimentally confirmed using site-directed mutagenesis.Conclusions
Our results provide strong support for the use of evolutionary models applied to cross-sectional viral neutralization data to identify the epitopes of serum antibodies that confer neutralization breadth.997.
Antoine Roquilly Cécile Braudeau Raphael Cinotti Erwan Dumonte Rémi Motreul Régis Josien Karim Asehnoune 《PloS one》2013,8(8)
Previous Presentation
Portions of this study were presented at the Annual Congress of Société Française d’Anesthésie et de Réanimation in Paris, September 2012.Background
Toll-like receptor (TLR) agonists are promising therapy for the prevention of nosocomial infections in critical ill patients. We aimed to analyze the TLR-reactivity of circulating dendritic cells (DC) as assessed by cytokine production after an ex vivo challenge with TLR agonists in aneurysmal subarachnoid hemorrhage (SAH) patients.Methods and Findings
A single-center prospective observational study took place in one intensive care unit of a teaching hospital. Blood samples were harvested on days 2, 5 and 10 in 21 severe SAH patients requiring mechanical ventilation and 17 healthy controls. DC production of cytokines (Tumour Necrosis Factor, TNF-α; Interleukin, IL-12; and Interferon, IFN-α) was assessed by intracellular immunostaining on TLR-3, 4, 7/8 and 9 stimulations. SAH patients had decreased numbers of blood myeloid (mDCs) and plasmacytoid DCs (pDCs) on days 2, 5 and 10. Compared with the healthy controls, the frequency of mDCs producing TNF-α after TLR-3 stimulation was decreased in the SAH patients. The frequency of myeloid DCs producing IL-12 after TLR-3 and 4 stimulations was also decreased in the SAH patients. In contrast, the mDCs response to TLR-7/8 was not impaired in the SAH patients. The frequency of pDCs producing TNF-α+ and IFN-α+ on TLR-7/8 stimulation were reduced at all of the tested times in the SAH patients, whereas reactivity to TLR-9 was preserved. On day 2, the pDCs from non-survivor patients (n = 8) had a decreased ability to produce IFN-α on TLR-9 stimulation compared with the survivors.Conclusions
These data suggest functional abnormalities of circulating pDCs and mDCs that could be important for immunomodulation after SAH. 相似文献998.
Michael A. Rubin Makoto Jones Molly Leecaster Karim Khader Willy Ray Angela Huttner Benedikt Huttner Damon Toth Theodore Sablay Robert J. Borotkanics Dale N. Gerding Matthew H. Samore 《PloS one》2013,8(11)
Background
Clostridium difficile is one of the most common and important nosocomial pathogens, causing severe gastrointestinal disease in hospitalized patients. Although "bundled" interventions have been proposed and promoted, optimal control strategies remain unknown.Methods
We designed an agent-based computer simulation of nosocomial C. difficile transmission and infection, which included components such as: patients and health care workers, and their interactions; room contamination via C. difficile shedding; C. difficile hand carriage and removal via hand hygiene; patient acquisition of C. difficile via contact with contaminated rooms or health care workers; and patient antimicrobial use. We then introduced six interventions, alone and "bundled" together: aggressive C. difficile testing; empiric isolation and treatment of symptomatic patients; improved adherence to hand hygiene and contact precautions; improved use of soap and water for hand hygiene; and improved environmental cleaning. All interventions were tested using values representing base-case, typical intervention, and optimal intervention scenarios.Findings
In the base-case scenario, C. difficile infection rates ranged from 8–21 cases/10,000 patient-days, with a case detection fraction between 32%–50%. Implementing the "bundle" at typical intervention levels had a large impact on C. difficile acquisition and infection rates, although intensifying the intervention to optimal levels had much less additional impact. Most of the impact came from improved hand hygiene and empiric isolation and treatment of suspected C. difficile cases.Conclusion
A "bundled" intervention is likely to reduce nosocomial C. difficile infection rates, even under typical implementation conditions. Real-world implementation of the "bundle" should focus on those components of the intervention that are likely to produce the greatest impact on C. difficile infection rates, such as hand hygiene and empiric isolation and treatment of suspected cases. 相似文献999.
Cheng-Ping Mao Martin R. Brovarney Karim Dabbagh Herbert F. Birnb?ck Wolfgang F. Richter Christopher J. Del Nagro 《PloS one》2013,8(11)
The CD20-specific monoclonal antibody rituximab (MabThera®, Rituxan®) is widely used as the backbone of treatment for patients with hematologic disorders. Intravenous administration of rituximab is associated with infusion times of 4–6 hours, and can be associated with infusion-related reactions. Subcutaneous administration of rituximab may reduce this and facilitate administration without infusion-related reactions. We sought to determine the feasibility of achieving equivalent efficacy (measured by endogenous B-cell depletion) and long-term durability of CD20 target coverage for subcutaneously administered rituximab compared with intravenous dosing. In these preclinical studies, male cynomolgus monkeys were treated with either intravenous rituximab or novel subcutaneous formulation of rituximab containing human recombinant DNA-derived hyaluronidase enzyme. Peripheral blood samples were analyzed for serum rituximab concentrations, peripheral B-cell depletion, and CD20 target coverage, including subset analysis according to CD21+ status. Distal lymph node B-cell depletion and CD20 target coverage were also measured. Initial peak serum concentrations of rituximab were significantly higher following intravenous administration than subcutaneous. However, the mean serum rituximab trough concentrations were comparable at 2 and 7 days post-first dose and 9 and 14 days post-second dose. Efficacy of B-cell depletion in both peripheral blood and distal lymph nodes was comparable for both methods. In lymph nodes, 9 days after the second dose with subcutaneous and intravenous rituximab, B-cell levels were decreased by 57% and 42% respectively. Similarly, levels of peripheral blood B cells were depleted by >94% for both subcutaneous and intravenous dosing at all time points. Long-term recovery of free unbound surface CD20 levels was similar, and the duration of B-cell depletion was equally sustained over 2 months for both methods. These results demonstrate that, despite initial peak serum drug level differences, subcutaneous rituximab has similar durability, pharmacodynamics, and efficacy compared with intravenous rituximab. 相似文献
1000.
Magdalena Foltman Cecile Evrin Giacomo De Piccoli Richard C. Jones Rick D. Edmondson Yuki Katou Ryuichiro Nakato Katsuhiko Shirahige Karim Labib 《Cell reports》2013,3(3):892-904
Highlights? FACT associates with the replisome, but not with the Mcm2-7 helicase, at origins ? Mcm2 and FACT bind together to histones released from chromatin ? Mcm2 has a conserved histone-binding motif in its amino terminal tail ? Histone binding by Mcm2 contributes to the efficacious replication of chromatin 相似文献