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491.
492.
Mar Abril-Gil Alba Garcia-Just Francisco J. Pérez-Cano àngels Franch Margarida Castell 《PloS one》2015,10(4)
Background
Food allergy (FA) is an adverse health effect produced by the exposure to a given food. Currently, there is no optimal animal model of FA for the screening of immunotherapies or for testing the allergenicity of new foods.Objective
The aim of the present study was to develop an effective and rapid model of FA in Brown Norway rats. In order to establish biomarkers of FA in rat, we compared the immune response and the anaphylactic shock obtained in this model with those achieved with only intraperitoneal immunization.Methods
Rats received an intraperitoneal injection of ovalbumin (OVA) with alum and toxin from Bordetella pertussis, and 14 days later, OVA by oral route daily for three weeks (FA group). A group of rats receiving only the i.p. injection (IP group) were also tested. Serum anti-OVA IgE, IgG1, IgG2a, IgG2b and IgA antibodies were quantified throughout the study. After an oral challenge, body temperature, intestinal permeability, motor activity, and mast cell protease II (RMCP-II) levels were determined. At the end of the study, anti-OVA intestinal IgA, spleen cytokine production, lymphocyte composition of Peyer’s patches and mesenteric lymph nodes, and gene expression in the small intestine were quantified.Results
Serum OVA-specific IgG1, IgG2a and IgG2b concentrations rose with the i.p. immunization but were highly augmented after the oral OVA administration. Anti-OVA IgE increased twofold during the first week of oral OVA gavage. The anaphylaxis in both IP and FA groups decreased body temperature and motor activity, whereas intestinal permeability increased. Interestingly, the FA group showed a much higher RMCP II serum protein and intestinal mRNA expression.Conclusions
These results show both an effective and relatively rapid model of FA assessed by means of specific antibody titres and the high production of RMCP-II and its intestinal gene expression. 相似文献493.
José A. Brito Kevin Denkmann Inês A. C. Pereira Margarida Archer Christiane Dahl 《The Journal of biological chemistry》2015,290(14):9222-9238
Although the oxidative condensation of two thiosulfate anions to tetrathionate constitutes a well documented and significant part of the natural sulfur cycle, little is known about the enzymes catalyzing this reaction. In the purple sulfur bacterium Allochromatium vinosum, the reaction is catalyzed by the periplasmic diheme c-type cytochrome thiosulfate dehydrogenase (TsdA). Here, we report the crystal structure of the “as isolated” form of A. vinosum TsdA to 1.98 Å resolution and those of several redox states of the enzyme to different resolutions. The protein contains two typical class I c-type cytochrome domains wrapped around two hemes axially coordinated by His53/Cys96 and His164/Lys208. These domains are very similar, suggesting a gene duplication event during evolution. A ligand switch from Lys208 to Met209 is observed upon reduction of the enzyme. Cys96 is an essential residue for catalysis, with the specific activity of the enzyme being completely abolished in several TsdA-Cys96 variants. TsdA-K208N, K208G, and M209G variants were catalytically active in thiosulfate oxidation as well as in tetrathionate reduction, pointing to heme 2 as the electron exit point. In this study, we provide spectroscopic and structural evidence that the TsdA reaction cycle involves the transient presence of heme 1 in the high-spin state caused by movement of the Sγ atom of Cys96 out of the iron coordination sphere. Based on the presented data, we draw important conclusions about the enzyme and propose a possible reaction mechanism for TsdA. 相似文献
494.
Abdelilah Arredouani Margarida Ruas Stephan C. Collins Raman Parkesh Frederick Clough Toby Pillinger George Coltart Katja Rietdorf Andrew Royle Paul Johnson Matthias Braun Quan Zhang William Sones Kenju Shimomura Anthony J. Morgan Alexander M. Lewis Kai-Ting Chuang Ruth Tunn Joaquin Gadea Lydia Teboul Paula M. Heister Patricia W. Tynan Elisa A. Bellomo Guy A. Rutter Patrik Rorsman Grant C. Churchill John Parrington Antony Galione 《The Journal of biological chemistry》2015,290(35):21376-21392
Pancreatic β cells are electrically excitable and respond to elevated glucose concentrations with bursts of Ca2+ action potentials due to the activation of voltage-dependent Ca2+ channels (VDCCs), which leads to the exocytosis of insulin granules. We have examined the possible role of nicotinic acid adenine dinucleotide phosphate (NAADP)-mediated Ca2+ release from intracellular stores during stimulus-secretion coupling in primary mouse pancreatic β cells. NAADP-regulated Ca2+ release channels, likely two-pore channels (TPCs), have recently been shown to be a major mechanism for mobilizing Ca2+ from the endolysosomal system, resulting in localized Ca2+ signals. We show here that NAADP-mediated Ca2+ release from endolysosomal Ca2+ stores activates inward membrane currents and depolarizes the β cell to the threshold for VDCC activation and thereby contributes to glucose-evoked depolarization of the membrane potential during stimulus-response coupling. Selective pharmacological inhibition of NAADP-evoked Ca2+ release or genetic ablation of endolysosomal TPC1 or TPC2 channels attenuates glucose- and sulfonylurea-induced membrane currents, depolarization, cytoplasmic Ca2+ signals, and insulin secretion. Our findings implicate NAADP-evoked Ca2+ release from acidic Ca2+ storage organelles in stimulus-secretion coupling in β cells. 相似文献
495.
Isabel Paiva Rui M. Gil da Costa Joana Ribeiro Hugo Sousa Margarida Bastos Ana Faustino Carlos Rocha Paula A Oliveira Rui Medeiros 《PloS one》2015,10(1)
Human Papillomavirus cause a number of diseases most notably cervical cancer. K14-HPV16 transgenic mice expressing the HPV16 early genes in squamous epithelial cells provide a suitable experimental model for studying these diseases. MicroRNAs are small non-coding RNAs that play an important role in regulating gene expression and have been suggested to play an important role in cancer development. The role of miR-155 in cancer remains controversial and there is limited evidence linking this miRNA to HPV- associated diseases. We hypothesized that miR-155 expression modulates each tissue’s susceptibility to develop HPV-associated carcinogenesis. In this study, we analyzed miR-155 expression in ear and chest skin samples from 22-26 weeks old, female K14-HPV16 transgenic (HPV16+/-) and wild-type (HPV-/-) mice. Among wild-type mice the expression of miR-155 was lower in ear skin compared with chest skin (p = 0.028). In transgenic animals, in situ carcinoma was present in all ear samples whereas chest tissues only showed epidermal hyperplasia. Furthermore, in hyperplastic chest skin samples, miR-155 expression was lower than in normal chest skin (p = 0,026). These results suggest that miR-155 expression may modulate the microenvironmental susceptibility to cancer development and that high miR155 levels may be protective against the carcinogenesis induced by HPV16. 相似文献
496.
Cláudio Nunes-Alves Matthew G. Booty Stephen M. Carpenter Alissa C. Rothchild Constance J. Martin Danielle Desjardins Katherine Steblenko Henrik N. Kl?verpris Rajhmun Madansein Duran Ramsuran Alasdair Leslie Margarida Correia-Neves Samuel M. Behar 《PLoS pathogens》2015,11(5)
The immune system can recognize virtually any antigen, yet T cell responses against several pathogens, including Mycobacterium tuberculosis, are restricted to a limited number of immunodominant epitopes. The host factors that affect immunodominance are incompletely understood. Whether immunodominant epitopes elicit protective CD8+ T cell responses or instead act as decoys to subvert immunity and allow pathogens to establish chronic infection is unknown. Here we show that anatomically distinct human granulomas contain clonally expanded CD8+ T cells with overlapping T cell receptor (TCR) repertoires. Similarly, the murine CD8+ T cell response against M. tuberculosis is dominated by TB10.44-11-specific T cells with extreme TCRβ bias. Using a retrogenic model of TB10.44-11-specific CD8+ T cells, we show that TCR dominance can arise because of competition between clonotypes driven by differences in affinity. Finally, we demonstrate that TB10.4-specific CD8+ T cells mediate protection against tuberculosis, which requires interferon-γ production and TAP1-dependent antigen presentation in vivo. Our study of how immunodominance, biased TCR repertoires, and protection are inter-related, provides a new way to measure the quality of T cell immunity, which if applied to vaccine evaluation, could enhance our understanding of how to elicit protective T cell immunity. 相似文献
497.
Morphological and genetic diversity of the family Azollaceae inferred from vegetative characters and RAPD markers 总被引:1,自引:0,他引:1
Ana L. Pereira Madalena Martins M. Margarida Oliveira Francisco Carrapi?o 《Plant Systematics and Evolution》2011,297(3-4):213-226
Family Azollaceae has seven species with a controversial taxonomy. The identification of species without reproductive structures relies on vegetative characters but some are variable, leading to misinterpretations. The molecular methods may be helpful, but until now, they did not provide a conclusive Azolla taxonomy. Therefore, we studied the family Azollaceae at vegetative and molecular levels. Analysis of vegetative, random amplified polymorphic DNA (RAPD) and combined data showed a comparable grouping of the Azolla species in two main clusters: cluster I, referred to as section Rhizosperma (A. pinnata and A. nilotica) and cluster II, referred to as section Azolla (A. filiculoides, A. microphylla, A. caroliniana and A. mexicana), with the exception of A. rubra, which clustered differently depending on the method. All the Azolla species were distinguished by the 13 polymorphic vegetative characters, the 211 RAPD markers or the combined data, with the latest showing the highest discrimination. The Shannon Index diversity was greater with RAPD (2.276) than with vegetative characters (0.054), highlighting the higher discriminating power of the molecular data. The partitioning of diversity was, as expected, high among species for all the types of data and low within species, with the lowest diversity obtained for morphological data. Both data sets (vegetative and RAPD) allowed the distinction of all the species and their clustering into sections Rhizosperma and Azolla, suggesting this as the most correct for this family. The dendrogram from the combined data was the most accurate, highlighting the benefit of integrating different types of data to study the family Azollaceae. 相似文献
498.
Fernandes MM Gomes AC Vasconcelos A Munteanu FD Tzanov T Gonçalves MS End N Schoening KU Guebitz GM Cavaco-Paulo A 《Applied microbiology and biotechnology》2011,90(4):1311-1321
In living systems, protein disulphide isomerase (PDI, EC 5.3.4.1) regulates the formation of new disulphide bonds in proteins
(oxidase activity) and catalyzes the rearrangement of non-native disulphide bonds (isomerase activity), leading proteins towards
their native configuration. In this study, PDI was used to attach cysteine-containing compounds (CCCs) onto hair, to enhance
compound migration within hair fibre and to trigger protein release. A fluorescent (5(6)-TAMRA)-labelled keratin peptide was
incorporated into hair by using PDI. Similarly, PDI promoted the grafting of a cysteine-functionalized dye onto wool, as suggested
by matrix-assisted laser desorption and ionization time-of-flight results. These reactions were thought to involve oxidation
of disulphide bonds between CCCs and wool or hair cysteine residues, catalyzed by the oxidized PDI active site. On the other
hand, PDI was demonstrated to enhance the migration of a disulphide bond-functionalized dye within the keratin matrix and
trigger the release of RNase A from wool fibres’ surface. These observations may indicate that an isomerisation reaction occurred,
catalyzed by the reduced PDI active site, to achieve the thiol-disulphide exchange, i.e. the rearrangement of disulphide bonds
between CCCs and keratin. The present communication aims to highlight promising biotechnological applications of PDI, derived
from its almost unique properties within the isomerase family. 相似文献
499.
Antimicrobial residue deposition can change the physico-chemical properties of bacteria and surfaces and thus promote or impair bacterial adhesion. This study focuses on benzalkonium chloride (BC) deposition on polystyrene (PS) surfaces and the influence of this conditioning film on the physico-chemical properties of PS and on early adhesion and biofilm formation by Pseudomonas aeruginosa wild-type and its laboratory BC-adapted strain. The latter readily acquired the ability to grow in BC, and also exhibited physico-chemical surface changes. The existence of residues on PS surfaces altered their hydrophobicity and favoured adhesion as determined by the free energy and early adhesion characterization. Adapted bacteria revealed a higher ability to adhere to surfaces and to develop biofilms, especially on BC-conditioned surfaces, which thereby could enhance resistance to sanitation attempts. These findings highlight the importance of investigations concerning the antimicrobial deposition effect after cleaning procedures, which may encourage bacterial adhesion, especially of bacteria that have been previously exposed to chemical stresses. 相似文献
500.