全文获取类型
收费全文 | 1682篇 |
免费 | 108篇 |
国内免费 | 38篇 |
专业分类
1828篇 |
出版年
2023年 | 16篇 |
2022年 | 37篇 |
2021年 | 41篇 |
2020年 | 28篇 |
2019年 | 43篇 |
2018年 | 35篇 |
2017年 | 26篇 |
2016年 | 57篇 |
2015年 | 82篇 |
2014年 | 111篇 |
2013年 | 127篇 |
2012年 | 140篇 |
2011年 | 134篇 |
2010年 | 88篇 |
2009年 | 54篇 |
2008年 | 88篇 |
2007年 | 68篇 |
2006年 | 67篇 |
2005年 | 56篇 |
2004年 | 52篇 |
2003年 | 54篇 |
2002年 | 47篇 |
2001年 | 48篇 |
2000年 | 35篇 |
1999年 | 27篇 |
1998年 | 6篇 |
1997年 | 13篇 |
1996年 | 8篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 22篇 |
1991年 | 15篇 |
1990年 | 21篇 |
1989年 | 13篇 |
1988年 | 18篇 |
1987年 | 12篇 |
1986年 | 10篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1981年 | 7篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1972年 | 7篇 |
1971年 | 6篇 |
排序方式: 共有1828条查询结果,搜索用时 10 毫秒
171.
Cytoplasmic receptor-interacting protein 140 (RIP140) interacts with perilipin to regulate lipolysis
Receptor-interacting protein 140 (RIP140) is abundantly expressed in mature adipocyte and modulates gene expression involved in lipid and glucose metabolism. Protein kinase C epsilon and protein arginine methyltransferase 1 can sequentially stimulate RIP140 phosphorylation and then methylation, thereby promoting its export to the cytoplasm. Here we report a lipid signal triggering cytoplasmic accumulation of RIP140, and a new functional role for cytoplasmic RIP140 in adipocyte to regulate lipolysis. Increased lipid content, particularly an elevation in diacylglycerol levels, promotes RIP140 cytoplasmic accumulation and increased association with lipid droplets (LDs) by its direct interaction with perilipin. By interacting with RIP140, perilipin more efficiently recruits hormone-sensitive lipase (HSL) to LDs and enhances adipose triglyceride lipase (ATGL) forming complex with CGI-58, an activator of ATGL. Consequentially, HSL can more readily access its substrates, and ATGL is activated, ultimately enhancing lipolysis. In adipocytes, blocking cytoplasmic RIP140 accumulation reduces basal and isoproterenol-stimulated lipolysis and the pro-inflammatory potential of their conditioned media (i.e. activating NF-κB and inflammatory genes in macrophages). These results show that in adipocytes with high lipid contents, RIP140 increasingly accumulates in the cytoplasm and enhances triglyceride catabolism by directly interacting with perilipin. The study suggests that reducing nuclear export of RIP140 might be a useful means of controlling adipocyte lipolysis. 相似文献
172.
Yu-Fen Tseng Chien-Chih Wang Shuen-Kuei Liao Ching-Kai Chuang Wei-June Chen 《Journal of biomedical science》2011,18(1):20
Japanese encephalitis (JE) virus is the most common cause of epidemic viral encephalitis in the world. The virus mainly infects
neuronal cells and causes an inflammatory response after invasion of the parenchyma of the brain. The death of neurons is
frequently observed, in which demyelinated axons are commonly seen. The mechanism that accounts for the occurrence of demyelination
is ambiguous thus far. With a mouse model, the present study showed that myelin-specific antibodies appeared in sera, particularly
in those mice with evident symptoms. Meanwhile, specific T cells proliferating in response to stimulation by myelin basic
protein (MBP) was also shown in these mice. Taken together, our results suggest that autoimmunity may play an important role
in the destruction of components, e.g., MBP, of axon-surrounding myelin, resulting in demyelination in the mouse brain after infection with the JE virus. 相似文献
173.
Background
NADH dehydrogenase (ubiquinone) flavoprotein 2 (NDUFV2), containing one iron sulfur cluster ([2Fe-2S] binuclear cluster N1a), is one of the core nuclear-encoded subunits existing in human mitochondrial complex I. Defects in this subunit have been associated with Parkinson's disease, Alzheimer's disease, Bipolar disorder, and Schizophrenia. The aim of this study is to examine the mitochondrial targeting of NDUFV2 and dissect the pathogenetic mechanism of one human deletion mutation present in patients with early-onset hypertrophic cardiomyopathy and encephalopathy. 相似文献174.
Dengue virus (DENV) infection can cause mild dengue fever or severe dengue hemorrhage fever (DHF) and dengue shock syndrome (DSS). Serum levels of the macrophage migration inhibitory factor (MIF) have been shown to be correlated with severity and mortality in DENV patients, but the pathogenic roles of MIF in DHF/DSS are still unclear. Increase in vascular permeability is an important hallmark of DHF/DSS. In this study, we found that DENV infection of the human hepatoma cell line (Huh 7) induced MIF production. Conditioned medium collected from DENV-infected Huh 7 cells enhanced the permeability of the human endothelial cell line (HMEC-1) which was reduced in the presence of a MIF inhibitor, ISO-1 or medium from DENV-infected MIF knockdown Huh 7 cells. To further identify whether MIF can alter vascular permeability, we cloned and expressed both human and murine recombinant MIF (rMIF) and tested their effects on vascular permeability both in vitro and in vivo. Indirect immunofluorescent staining showed that the tight junction protein ZO-1 of HMEC-1 was disarrayed in the presence of rMIF and partially recovered when cells were treated with ISO-1 or PI3K/MEK-ERK/JNK signaling pathway inhibitors such as Ly294002, U0126, and SP600215. In addition, ZO-1 disarray induced by MIF was also recovered when CD74 or CXCR2/4 expression of HMEC-1 were inhibited. Last but not least, the vascular permeabilities of the peritoneal cavity and dorsal cutaneous capillary were also increased in mice treated with rMIF. Taken together; these results suggest that MIF induced by DENV infection may contribute to the increase of vascular permeability during DHF/DSS. Therapeutic intervention of MIF by its inhibitor or neutralizing antibodies may prevent DENV-induced lethality. 相似文献
175.
Background
Preclinical and observational studies raise the concern about the safety of insulin glargine in terms of cancer initiation and promotion. This study is designed to examine cancer incidence associated with use of insulin glargine vs. intermediate/long-acting human insulin (HI).Methodology
A retrospective cohort study using the Taiwan National Health Insurance claims database was conducted to identify adult patients with type 2 diabetes mellitus and without a history of cancer who initiated insulin glargine (n = 10,190) or intermediate/long-acting HI (n = 49,253) during 2004–2007. Exclusive users were followed from the date of insulin initiation to the earliest of cancer diagnosis, death, disenrollment, or December 31 2007. We estimated adjusted hazard ratios and 95% confidence intervals (CIs) with Cox proportional hazards models adjusting for baseline propensity score.Findings
The incidence rate of all cancer per 1,000 person-years was 13.8 for insulin glargine initiators (179 cases) and 16.0 for intermediate/long-acting HI initiators (1,445 cases) during an average follow-up of 2 years. No significant difference in overall cancer risk between insulin glargine initiators and HI initiators was found. For men, however, the adjusted hazard ratio of insulin glargine use as compared with intermediate/long-acting HI was 2.15 (95% CI 1.01–4.59) for pancreatic cancer, and 2.42 (95% CI 1.50–8.40) for prostate cancer. The increased risk was not observed among women.Conclusions
Insulin glargine use did not increase the risk of overall cancer incidence as compared with HI. The positive associations with pancreatic and prostate cancer need further evaluation and validation. 相似文献176.
177.
Rane AA Chuang JS Shah A Hu DP Dalton ND Gu Y Peterson KL Omens JH Christman KL 《PloS one》2011,6(6):e21571
Background
Several injectable materials have been shown to preserve or improve cardiac function as well as prevent or slow left ventricular (LV) remodeling post-myocardial infarction (MI). However, it is unclear as to whether it is the structural support or the bioactivity of these polymers that lead to beneficial effects. Herein, we examine how passive structural enhancement of the LV wall by an increase in wall thickness affects cardiac function post-MI using a bio-inert, non-degradable synthetic polymer in an effort to better understand the mechanisms by which injectable materials affect LV remodeling.Methods and Results
Poly(ethylene glycol) (PEG) gels of storage modulus G′ = 0.5±0.1 kPa were injected and polymerized in situ one week after total occlusion of the left coronary artery in female Sprague Dawley rats. The animals were imaged using magnetic resonance imaging (MRI) at 7±1 day(s) post-MI as a baseline and again post-injection 49±4 days after MI. Infarct wall thickness was statistically increased in PEG gel injected vs. control animals (p<0.01). However, animals in the polymer and control groups showed decreases in cardiac function in terms of end diastolic volume, end systolic volume and ejection fraction compared to baseline (p<0.01). The cellular response to injection was also similar in both groups.Conclusion
The results of this study demonstrate that passive structural reinforcement alone was insufficient to prevent post-MI remodeling, suggesting that bioactivity and/or cell infiltration due to degradation of injectable materials are likely playing a key role in the preservation of cardiac function, thus providing a deeper understanding of the influencing properties of biomaterials necessary to prevent post-MI negative remodeling. 相似文献178.
Lactoferricin B (LfcinB) is a well-known antimicrobial peptide. Several studies have indicated that it can inhibit bacteria by affecting intracellular activities, but the intracellular targets of this antimicrobial peptide have not been identified. Therefore, we used E. coli proteome chips to identify the intracellular target proteins of LfcinB in a high-throughput manner. We probed LfcinB with E. coli proteome chips and further conducted normalization and Gene Ontology (GO) analyses. The results of the GO analyses showed that the identified proteins were associated with metabolic processes. Moreover, we validated the interactions between LfcinB and chip assay-identified proteins with fluorescence polarization (FP) assays. Sixteen proteins were identified, and an E. coli interaction database (EcID) analysis revealed that the majority of the proteins that interact with these 16 proteins affected the tricarboxylic acid (TCA) cycle. Knockout assays were conducted to further validate the FP assay results. These results showed that phosphoenolpyruvate carboxylase was a target of LfcinB, indicating that one of its mechanisms of action may be associated with pyruvate metabolism. Thus, we used pyruvate assays to conduct an in vivo validation of the relationship between LfcinB and pyruvate level in E. coli. These results showed that E. coli exposed to LfcinB had abnormal pyruvate amounts, indicating that LfcinB caused an accumulation of pyruvate. In conclusion, this study successfully revealed the intracellular targets of LfcinB using an E. coli proteome chip approach. 相似文献
179.
Tamminga C Sedegah M Regis D Chuang I Epstein JE Spring M Mendoza-Silveiras J McGrath S Maiolatesi S Reyes S Steinbeiss V Fedders C Smith K House B Ganeshan H Lejano J Abot E Banania GJ Sayo R Farooq F Belmonte M Murphy J Komisar J Williams J Shi M Brambilla D Manohar N Richie NO Wood C Limbach K Patterson NB Bruder JT Doolan DL King CR Diggs C Soisson L Carucci D Levine G Dutta S Hollingdale MR Ockenhouse CF Richie TL 《PloS one》2011,6(10):e25868
Background
A protective malaria vaccine will likely need to elicit both cell-mediated and antibody responses. As adenovirus vaccine vectors induce both these responses in humans, a Phase 1/2a clinical trial was conducted to evaluate the efficacy of an adenovirus serotype 5-vectored malaria vaccine against sporozoite challenge.Methodology/Principal Findings
NMRC-MV-Ad-PfC is an adenovirus vector encoding the Plasmodium falciparum 3D7 circumsporozoite protein (CSP). It is one component of a two-component vaccine NMRC-M3V-Ad-PfCA consisting of one adenovector encoding CSP and one encoding apical membrane antigen-1 (AMA1) that was evaluated for safety and immunogenicity in an earlier study (see companion paper, Sedegah et al). Fourteen Ad5 seropositive or negative adults received two doses of NMRC-MV-Ad-PfC sixteen weeks apart, at particle units per dose. The vaccine was safe and well tolerated. All volunteers developed positive ELISpot responses by 28 days after the first immunization (geometric mean 272 spot forming cells/million[sfc/m]) that declined during the following 16 weeks and increased after the second dose to levels that in most cases were less than the initial peak (geometric mean 119 sfc/m). CD8+ predominated over CD4+ responses, as in the first clinical trial. Antibody responses were poor and like ELISpot responses increased after the second immunization but did not exceed the initial peak. Pre-existing neutralizing antibodies (NAb) to Ad5 did not affect the immunogenicity of the first dose, but the fold increase in NAb induced by the first dose was significantly associated with poorer antibody responses after the second dose, while ELISpot responses remained unaffected. When challenged by the bite of P. falciparum-infected mosquitoes, two of 11 volunteers showed a delay in the time to patency compared to infectivity controls, but no volunteers were sterilely protected.Significance
The NMRC-MV-Ad-PfC vaccine expressing CSP was safe and well tolerated given as two doses, but did not provide sterile protection.Trial Registration
ClinicalTrials.gov NCT00392015相似文献180.
Chen CS Anaya JM Zhang S Spurgin J Chuang CY Xu C Miao AJ Chen EY Schwehr KA Jiang Y Quigg A Santschi PH Chin WC 《PloS one》2011,6(7):e21865
The unique properties of engineered nanoparticles (ENs) that make their industrial applications so attractive simultaneously raise questions regarding their environmental safety. ENs exhibit behaviors different from bulk materials with identical chemical compositions. Though the nanotoxicity of ENs has been studied intensively, their unintended environmental impacts remain largely unknown. Herein we report experimental results of EN interactions with exopolymeric substances (EPS) from three marine phytoplankton species: Amphora sp., Ankistrodesmus angustus and Phaeodactylum tricornutum. EPS are polysaccharide-rich anionic colloid polymers released by various microorganisms that can assemble into microgels, possibly by means of hydrophobic and ionic mechanisms. Polystyrene nanoparticles (23 nm) were used in our study as model ENs. The effects of ENs on EPS assembly were monitored with dynamic laser scattering (DLS). We found that ENs can induce significant acceleration in Amphora sp. EPS assembly; after 72 hours EN-EPS aggregation reached equilibrium, forming microscopic gels of ~4-6 μm in size. In contrast, ENs only cause moderate assembly kinetic acceleration for A. angustus and P. tricornutum EPS samples. Our results indicate that the effects of ENs on EPS assembly kinetics mainly depend on the hydrophobic interactions of ENs with EPS polymers. The cycling mechanism of EPS is complex. Nonetheless, the change of EPS assembly kinetics induced by ENs can be considered as one potential disturbance to the marine carbon cycle. 相似文献