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排序方式: 共有343条查询结果,搜索用时 15 毫秒
61.
Muthu Manikandan Lejla Pašić Vijayaraghavan Kannan 《World journal of microbiology & biotechnology》2009,25(12):2247-2256
An extremely halophilic archaeon Haloferax lucentensis VKMM 007, isolated from a solar saltern, was found to produce a protease. This extracellular enzyme consisted of a single
polypeptide chain of 57.8 kDa as determined by SDS–PAGE and was purified by a combination of ultrafiltration, bacitracin–Sepharose
affinity chromatography and Sephadex G-100 gel filtration. The purified protein was stable in a wide range of temperatures
(20–70°C), NaCl concentrations (0.85–5.13 M) and pH (5.0–9.0) with maximal activity observed at 60°C, 4.3 M NaCl and pH 8.0.
Proteolytic activity was enhanced by Ca2+, K+, Mg2+, Na+, and Fe2+ ions and the protein was classified as a trypsin-like serine protease. Further assays indicated highest degree of specificity
when hemoglobin was used as an enzyme substrate. Most importantly, the proteolytic activity remained stable or only marginally
inhibited in the presence of various polar and non-polar solvents, surfactants and reducing agents thus emphasizing the biotechnological
potential of this novel halophilic protease. 相似文献
62.
Palanisamy Jayakumar Esaki Muthu Shankar Murugesan Karthikeyan 《Bioscience Hypotheses》2009,2(5):282-285
Immune reconstitution inflammatory syndrome (IRIS) is an inflammatory manifestation that occurs subsequent to initiation of highly active antiretroviral therapy in terminal (HAART) HIV infection, mainly due to the restoration of robust immune responses directed against latent microbial antigens. IRIS is believed to be multifactorial and less studied. Herein, we postulate that hypothalamo-pituitary-adrenal (HPA) dysregulation, a well-documented manifestation in HIV/AIDS, could possibly disturb the balance between pro-inflammatory and anti-inflammatory cytokines leading to clinical IRIS. Drugs, opportunistic infections, stress and numerous intrinsic and extrinsic factors have been described to be the possible causes of IRIS in HIV illness. 相似文献
63.
Esaki Muthu Shankar Ramachandran Vignesh Esakimuthu Ponmalar Muthu Sundaram Suniti Solomon 《Bioscience Hypotheses》2009,2(3):125-127
Studies have shown that the more iron in a given population, the more that population is vulnerable to intracellular opportunistic infections (OIs) in AIDS, mainly because these microbes make use of the intracellular iron to proliferate, and could render infections deadly. In contrast, macrophages that lack iron are effective in preventing an establishment of infection. We propose that reduction in total body iron could be a valuable treatment option for some intracellular infections, including OIs. We suggest two options to deprive pathogens of using intracellular iron (i) to practice regular blood-letting, an ancient treatment option, and (ii) to down-regulate hepcidin, the key hormone involved in the regulation of iron balance and recycling. This could also deprive transformed cells of metabolizing iron for survival. Whether or these methods serve to curb the onset of OIs/cancers to prolong HIV disease progression remains to be investigated. 相似文献
64.
Muthu Veeraputhiran John W. Theus Gina Pesek Bart Barlogie Michele Cottler-Fox 《Cytotherapy》2010,12(6):764-766
Background aimsWe carried out a retrospective analysis of viability by diagnosis and dimethyl sulfoxide (DMSO) concentration in patients who had undergone autologous transplants using hematopoietic progenitor cells (HPC) after long-term storage (up to 17.8 years).MethodsViability was tested using flow cytometry for HPC that were harvested and preserved using a controlled rate freezer and 5% or 10% DMSO with human serum albumin, then stored in liquid nitrogen. Data from 262 samples were analyzed (249 myeloma patients and 13 other diagnoses): 100 consecutively thawed samples with a storage time of <1 year (all 10% DMSO), 50 consecutive samples stored for 1–4.9 years (10% DMSO), 50 samples stored for 5–9 years (5% DMSO) and all samples stored and used for transplant after >9 years (60 samples, 5% DMSO; two samples, 10% DMSO).ResultsNo statistically significant difference in viability between the 5% DMSO and 10% DMSO groups was observed (P = 0.08), so the 1–4.9 years and 5–9 years were combined and the three groups (<1 year, 1–9 years and >9 years) were compared using an anova test. There was no difference in viability based on cryostorage period (P = 0.23) or between myeloma and other diagnoses (P = 0.45). No difference was seen in time to White blood cell (WBC) engraftment (P = 0.10) or to platelet engraftment between groups (P = 0.52).ConclusionsThese data suggest that long-term storage in 5% DMSO and human serum albumin is safe. 相似文献
65.
66.
Gomathi Nagarajan Vairamani Mariappanadar Muthu Tamizh Ilango Kaliappan 《Journal of receptor and signal transduction research》2017,37(3):304-313
Context: The histamine plays a decisive role in acute and chronic inflammatory responses and is regulated through its four types of distinct receptors designated from H1 to H4. Recently histamine 4 receptor (H4R) antagonists have been reported to possess various pharmacological effects against various allergic diseases.Objective: To investigate the inhibitory effect of N-(2-aminoethyl)-5-chloro-1H-indol-2-carboxamide (Compound A) and 5-chloro-2-(piperazin-1-ylmethyl)-1H-benzimidazole (Compound L) on H4R-mediated calcium mobilization, cytokine IL-13 production, ERK1/2, Akt and NF-κB activation in human mastocytoma cells-1 (HMC-1).Materials and methods: Compounds A and L were synthesized chemically and their inhibitory effect on intracellular calcium release was analyzed by Fluo-4 calcium assay, cytokine measurement through ELISA and activation of signaling molecules by western blot.Results: Pre-treatment with compounds A and L significantly reduced the H4R-mediated intracellular calcium release. Histamine and 4-methylhistamine (4-MH) induced Th2 cytokine IL-13 production in HMC-1 cells, was inhibited by compound A (77.61%, 74.25% at 1?μM concentration) and compound L (79.63%, 81.70% at 1?μM concentration). Furthermore, histamine induced the phosphorylation of ERK1/2, Akt and NF-κB was suppressed by compounds A and L at varying levels, ERK1/2 (88%, 86%), Akt (88%, 89%) and NF-κB (89%, 87%) in HMC-1 cells.Discussion and conclusions: Taken together these data demonstrate that compound A and compound L may block H4R-mediated downstream signaling events. 相似文献
67.
Carbazole–azine based fluorescence ‘off–on’ sensor for selective detection of Cu2+ and its live cell imaging
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Denzil Britto Christopher Leslee Sekar Karuppannan Karmegam Muthu Vengaian Sivaraman Gandhi Singaravadivel Subramanian 《Luminescence》2017,32(7):1354-1360
A new carbazole–azine based fluorescent sensor was synthesized and characterized. The selectivity of the sensor for Cu2+ over other counter ions in a dimethyl sulfoxide/H2O mixture was shown through enhancement in fluorescence – an off to on transformation. The specificity of the probe towards Cu2+ was evident in ultraviolet/visible, fluorescence, Fourier transform infrared and mass studies. Application of the probe in the cell imaging and cytotoxicity of living cells is illustrated. 相似文献
68.
Talukder MA Yang F Nishijima Y Chen CA Xie L Mahamud SD Kalyanasundaram A Bonagura JD Periasamy M Zweier JL 《American journal of physiology. Heart and circulatory physiology》2011,300(2):H702-H711
There is emerging evidence that treatment with thyroid hormone (TH) can improve postischemic cardiac function. 3,5-Diiodothyropropionic acid (DITPA), a TH analog, has been proposed to be a safer therapeutic agent than TH because of its negligible effects on cardiac metabolism and heart rate. However, conflicting results have been reported for the cardiac effects of DITPA. Importantly, recent clinical trials demonstrated no symptomatic benefit in patients with DITPA despite some improved hemodynamic and metabolic parameters. To address these issues, dose-dependent effects of DITPA were investigated in mice for baseline cardiovascular effects and postischemic myocardial function and/or salvage. Mice were treated with subcutaneous DITPA at 0.937, 1.875, 3.75, or 7.5 mg·kg(-1)·day(-1) for 7 days, and the results were compared with untreated mice for ex vivo and/or in vivo myocardial ischemia-reperfusion (I/R). DITPA had no effects on baseline body temperature, body weight, or heart rate; however, it mildly increased blood pressure. In isolated hearts, baseline contractile function was significantly impaired in DITPA-pretreated mice; however, postischemic recovery was comparable between untreated and DITPA-treated groups. In vivo baseline cardiac parameters were significantly affected by DITPA, with increased ventricular dimensions and decreased contractile function. Importantly, DITPA-treated mice demonstrated high prevalence of fatal cardiac rhythm abnormalities during in vivo ischemia and/or reperfusion. There were no improvements in myocardial infarction and postischemic fractional shortening with DITPA. Myocardial sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA), phospholamban (PLB), and heat shock protein (HSP) levels remained unchanged with DITPA treatment. Thus DITPA administration impairs baseline cardiac parameters in mice and can be fatal during in vivo acute myocardial I/R. 相似文献
69.
Bal NC Jena N Sopariwala D Balaraju T Shaikh S Bal C Sharon A Gyorke S Periasamy M 《The Biochemical journal》2011,435(2):391-399
CASQ (calsequestrin) is a Ca2+-buffering protein localized in the muscle SR (sarcoplasmic reticulum); however, it is unknown whether Ca2+ binding to CASQ2 is due to its location inside the SR rich in Ca2+ or due to its preference for Ca2+ over other ions. Therefore a major aim of the present study was to determine how CASQ2 selects Ca2+ over other metal ions by studying monomer folding and subsequent aggregation upon exposure to alkali (monovalent), alkaline earth (divalent) and transition (polyvalent) metals. We additionally investigated how CPVT (catecholaminergic polymorphic ventricular tachycardia) mutations affect CASQ2 structure and its molecular behaviour when exposed to different metal ions. Our results show that alkali and alkaline earth metals can initiate similar molecular compaction (folding), but only Ca2+ can promote CASQ2 to aggregate, suggesting that CASQ2 has a preferential binding to Ca2+ over all other metals. We additionally found that transition metals (having higher co-ordinated bonding ability than Ca2+) can also initiate folding and promote aggregation of CASQ2. These studies led us to suggest that folding and formation of higher-order structures depends on cationic properties such as co-ordinate bonding ability and ionic radius. Among the CPVT mutants studied, the L167H mutation disrupts the Ca2+-dependent folding and, when folding is achieved by Mn2+, L167H can undergo aggregation in a Ca2+-dependent manner. Interestingly, domain III mutants (D307H and P308L) lost their selectivity to Ca2+ and could be aggregated in the presence of Mg2+. In conclusion, these studies suggest that CPVT mutations modify CASQ2 behaviour, including folding, aggregation/polymerization and selectivity towards Ca2+. 相似文献
70.