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101.

Background

In this prospective study we sought to examine seroepidemiological evidence for acute zoonotic influenza virus infection among Romanian agricultural workers.

Methods

Sera were drawn upon enrollment (2009) and again at 12 and 24 months from 312 adult agriculture workers and 51 age-group matched controls. Participants were contacted monthly for 24 months and queried regarding episodes of acute influenza-like illnesses (ILI). Cohort members meeting ILI criteria permitted respiratory swab collections as well as acute and convalescent serum collection. Serologic assays were performed against 9 avian, 3 swine, and 3 human influenza viruses.

Results

During the two-year follow-up, a total of 23 ILI events were reported. Two subjects'' specimens were identified as influenza A by rRT-PCR. During the follow-up period, three individuals experienced elevated microneutralization antibody titers ≥1∶80 against three (one each) avian influenza viruses: A/Teal/Hong Kong/w312/97(H6N1), A/Hong Kong/1073/1999(H9N2), or A/Duck/Alberta/60/1976(H12N5). However, none of these participants met the criteria for poultry exposure. A number of subjects demonstrated four-fold increases over time in hemagglutination inhibition (HI) assay titers for at least one of the three swine influenza viruses (SIVs); however, it seems likely that two of these three responses were due to cross-reacting antibody against human influenza. Only elevated antibody titers against A/Swine/Flanders/1/1998(H3N2) lacked evidence for such confounding. In examining risk factors for elevated antibody against this SIV with multiple logistic regression, swine exposure (adjusted OR = 1.8, 95% CI 1.1–2.8) and tobacco use (adjusted OR = 1.8; 95% CI 1.1–2.9) were important predictors.

Conclusions

While Romania has recently experienced multiple incursions of highly pathogenic avian influenza among domestic poultry, this cohort of Romanian agriculture workers had sparse evidence of avian influenza virus infections. In contrast, there was evidence, especially among the swine exposed participants, of infections with human and one swine H3N2 influenza virus.  相似文献   
102.
103.
The manner in which centromere regions of mitotic chromosomes are distributed with respect to the age of their DNA was studied. Cells of the Indian deer, Muntiacus muntjak, were grown in the presence of bromodeoxyuridine (BrdU) for two generations and stained with the fluorescent dye Hoechst 33258. Chromatids containing granddaughter DNA appear dim when compared with those containing grandparental DNA. The frequencies of the various anaphase patterns of bright and dim centromere regions were binomially distributed, indicating random distribution of chromatids with respect to the age of their DNA templates.  相似文献   
104.
The relationship between nonsteroidal anti-inflammatory drugs (NSAIDs) and Helicobacter pylori-induced gastric mucosal injury is still under debate. VacA toxin is an important H. pylori virulence factor that causes cytoplasmic vacuolation in cultured cells. Whether and how NSAIDs affect VacA-induced cytotoxicity is unclear. This study was designed to evaluate the effect of NSAIDs on H. pylori VacA toxin-induced cell vacuolation in human gastric mucosal cells in culture (MKN 28 cell line). Our data show that 1) NSAIDs (indomethacin, aspirin, and NS-398) inhibit VacA-induced cell vacuolation independently of inhibition of cell proliferation and prostaglandin synthesis; 2) NSAIDs impair vacuole development/maintenance without affecting cell binding and internalization of VacA; and 3) NSAIDs, as well as the chloride channel blocker 5-nitro-2-(3-phenylpropylamino) benzoic acid, also inhibit cell vacuolation induced by ammonia. We thus hypothesize that NSAIDs might protect MKN 28 cells against VacA-induced cytotoxicity by inhibiting VacA channel activity required for vacuole genesis.  相似文献   
105.
An ultrastructural analysis of the gametogenetic phases in Branchiura sowerbyi, a tubificid oligochaete, has been accomplished. These phases mostly conform to the usual pattern for the family, however, some interesting peculiarities are pointed out. The regression of sexual apparatus after reproductive period and its regeneration up to a new period of sexual maturity, has been followed throughout the year.  相似文献   
106.
Glycoconjugate Journal - Neisseria meningitidis is a major cause of bacterial meningitidis worldwide. Children less than five years and adolescents are particularly affected. Nearly all invasive...  相似文献   
107.
The concentration of very-long-chain fatty acids (VLCFA) (straight chain, more than 22 carbon atoms) in plasma or in cultured fibroblasts is one of the most important diagnostic criteria for the diagnosis of the peroxisomal disorders. A sensitive method for VLCFA assay in plasma, using small sample volume and a simplified procedure, is described. After adequate extraction and derivatization, methyl esters of VLCFA are separated, identificated and quantified by gas chromatography—mass spectrometry (GC—MS). The method is sensitive, reproducible, accurate and relatively simple. GC—MS equipment used for routine organic acid analysis can be used.  相似文献   
108.
Like human immunodeficiency virus type 1 (HIV-1), most simian immunodeficiency virus (SIV) strains use CCR5 to establish infection. However, while HIV-1 can acquire the ability to use CXCR4, SIVs that utilize CXCR4 have rarely been reported. To explore possible barriers against SIV coreceptor switching, we derived an R5X4 variant, termed 239-ST1, from the R5 clone SIVmac239 by serially passaging virus in CD4+ CXCR4+ CCR5 SupT1 cells. A 239-ST1 env clone, designated 239-ST1.2-32, used CXCR4 and CCR5 in cell-cell fusion and reporter virus infection assays and conferred the ability for rapid, cytopathic infection of SupT1 cells to SIVmac239. Viral replication was inhibitable by the CXCR4-specific antagonist AMD3100, and replication was abrogated in a novel CXCR4 SupT1 line. Surprisingly, parental SIVmac239 exhibited low-level replication in SupT1 cells that was not observed in CXCR4 SupT1 cells. Only two mutations in the 239-ST1.2-32 Env, K47E in the C1 domain and L328W in the V3 loop, were required for CXCR4 use in cell-cell fusion assays, although two other V3 changes, N316K and I324M, improved CXCR4 use in infection assays. An Env cytoplasmic tail truncation, acquired during propagation of 239-ST1 in SupT1 cells, was not required. Compared with SIVmac239, 239-ST1.2-32 was more sensitive to neutralization by five of seven serum and plasma samples from SIVmac239-infected rhesus macaques and was approximately 50-fold more sensitive to soluble CD4. Thus, SIVmac239 can acquire the ability to use CXCR4 with high efficiency, but the changes required for this phenotype may be distinct from those for HIV-1 CXCR4 use. This finding, along with the increased neutralization sensitivity of this CXCR4-using SIV, suggests a mechanism that could select strongly against this phenotype in vivo.Simian immunodeficiency viruses (SIVs) share many structural and biological features with human immunodeficiency virus (HIV), including target cell entry via interactions of the viral envelope glycoprotein (Env) with CD4 and a chemokine coreceptor. For HIV, the most important coreceptors in vivo are CCR5 (2, 13, 19, 21, 22) and CXCR4 (30). HIV type 1 (HIV-1) strains that use only CCR5 (R5 viruses) predominate during the early stages of infection and are critical for transmission (84, 90), as evidenced by the finding that individuals lacking a functional CCR5 protein due to a homozygous 32-bp deletion in the CCR5 gene (ccr532) are largely resistant to HIV-1 infection (16, 54, 82). Although R5 viruses generally persist in late-stage disease, viruses that can use CXCR4, either exclusively (X4 viruses) or in addition to CCR5 (R5X4 viruses), emerge in approximately 50% of subtype B-infected individuals (15, 43). This coreceptor switch is associated with a more rapid decline in peripheral blood CD4+ T cells and a faster progression to AIDS (15, 43, 77), although it is unclear if CXCR4-using viruses are a cause or a consequence of progressing immunodeficiency. Like HIV, the vast majority of SIVs use CCR5 to establish infection (11, 12, 45). However, although CXCR4-using SIVs have been reported (47, 52, 65, 68, 69), their occurrence is rare, especially in models of pathogenic infection, where only one CXCR4-using SIV has been identified (17, 60, 71).This paucity of CXCR4-using SIVs is surprising for several reasons. First, SIV Envs tend to be more promiscuous than HIV-1 Envs and frequently use alternative coreceptors in addition to CCR5, including GPR1, GPR15, CXCR6, and CCR8 (20, 27, 29, 80, 81, 92) but not CXCR4. Second, HIV-2, which is more closely related to SIVmac than to HIV-1 (56, 57), commonly uses CXCR4 in vitro and in vivo (3, 28, 33, 58, 59, 67). Third, rhesus CXCR4 is ∼98% identical to human CXCR4 in amino acid sequence and can function as a coreceptor for HIV-1 in vitro (12). Finally, chimeric simian-human immunodeficiency viruses (SHIVs) that contain X4 HIV Envs on an SIV core can replicate to high levels in vivo and cause disease in rhesus macaques (39, 86). Moreover, it was recently shown that coreceptor switching can occur in rhesus macaques infected with an R5 SHIV (35). Thus, there does not appear to be any block per se against the use of rhesus CXCR4 as an entry coreceptor either in vitro or in vivo, suggesting that SIV is less capable of adapting to use CXCR4 and/or that mutations required for CXCR4 utilization may lead to a virus that is less fit and/or more susceptible to immune control in this host.For HIV-1, the Env determinants for CXCR4 use have been well documented and often involve the acquisition of positively charged amino acids in the V3 loop (18, 32, 87), particularly at positions 11, 24, and 25 (6, 18, 31, 32, 38, 75). Although the SIVmac239 V3 loop is a critical determinant for Env-coreceptor interactions (44, 63, 72), attempts to create an X4 SIVmac239 by introducing positively charged residues into the V3 loop (63) or by inserting a V3 loop from X4 HIV-1 (44) have been unsuccessful. SIVmac155T3, the only CXCR4-using variant of SIVmac that has been identified to date, was isolated from a rhesus macaque with advanced disease and contains additional positively charged residues in V3, although the determinants for CXCR4 use have not been determined (60, 71).Given questions concerning the possible determinants for and/or barriers to coreceptor switching in SIV, we sought to derive a CXCR4-using variant of the well-characterized pathogenic R5 SIV clone SIVmac239. Here we show that SIVmac239 could indeed acquire CXCR4 utilization when it was adapted in vitro for high-efficiency replication in the CXCR4+ CCR5 human SupT1 cell line. An env clone from this virus could use CXCR4 in cell-cell fusion and reporter virus infection assays and conferred CXCR4 tropism to a replication-competent SIV. Although V3 mutations were important for CXCR4 use, an L328W change at the V3 crown rather than the acquisition of positively charged residues was required, as was an unusual K47E mutation in the conserved C1 domain of gp120. These changes also caused the highly neutralization-resistant SIVmac239 strain to become more neutralization sensitive to sera and plasmas from SIVmac239-infected animals, and particularly to soluble CD4. These results indicate that mutations distinct from those typically seen for HIV-1 may be required for SIVmac to gain CXCR4 utilization and suggest that these changes render this virus more susceptible to humoral immune control. Collectively, our findings indicate that there are likely to be strong viral and host selection pressures against CXCR4 use that may contribute to the paucity of X4 coreceptor switching for SIVmac in vivo.  相似文献   
109.
The effects of an extract from Citrus bergamia (BSext) and those of two products purified from the same extract, that is, nomilin and limonin, and reference compounds, towards HTLV-1 have been reported. Moreover, they were also compared with those obtained towards HIV-1. Results showed that the efficacy of both BSext and limonin in inhibiting HTLV-1 as well as HIV-1 expression in infected cells, as evaluated by comparable quantitative assays, was close to that of the effective, reference compounds, respectively. The protective effect of BSext and of the purified products was associated with the inhibition of both HTLV-1 and HIV-1 RT activities in conceptually similar, cell-free assays. The cytotoxicity of the assayed compounds of natural origin was substantially less pronounced than that of the reference compounds, thus showing a favourable selectivity index for the novel BSext product.  相似文献   
110.
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