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101.
Sarcoplasmic reticulum (SR) Ca2+-ATPase was phosphorylated by Pi at pH 8.0 in the presence of dimethyl sulfoxide (Me2SO). Under these conditions, it was possible to measure transient 45Ca2+ binding to the phosphoenzyme. Binding reached 1.2 Ca2+ per phosphoenzyme (E-PCax) within 10 min in 30% Me2SO, 20 mM MgCl2 and 0.1 mM Pi and the phosphoenzyme only decreased by 23% during this period. This Ca2+ binding was abolished by thapsigargin, showing that it is associated with functional sites of the Ca2+-ATPase. At 40% Me2SO, simultaneous addition of Ca2+ and ADP increased Ca2+ binding up to almost four Ca2+ per phosphoenzyme (ADPE-PCay), revealing a species bearing simultaneously four Ca2+ sites. Both E-PCax and ADPE-PCay were further identified as distinct species by (2′,3′-O-2(2,4,6-trinitrophenyl)adenosine 5′-triphosphate) fluorescence, which revealed long-range modifications in the Ca2+-transport sites induced by ADP binding to E-P. In addition, E-PCax was shown to be a functional intermediate of the cycle leading to ATP synthesis provided that Me2SO was diluted. These findings indicate that more than two functional Ca2+-sites exist on the functional Ca2+-ATPase unit, and that the additional sites become accessible upon ADP addition. This is compatible with a four-site model of the SR Ca2+-ATPase allowing simultaneous binding of Ca2+ at lumenal and cytosolic sites. The stoichiometries for Ca2+ binding found here could either be interpreted as binding of four Ca2+ on a Ca2+-ATPase monomer considered as the functional unit or as binding of two Ca2+ per monomer of a functional dimer. 相似文献
102.
Amim LH Pacheco AG Fonseca-Costa J Loredo CS Rabahi MF Melo MH Ribeiro FC Mello FC Oliveira MM Lapa e Silva JR Ottenhoff TH Kritski AL Santos AR 《Molecular biology reports》2008,35(4):563-566
Several genetic cytokine gene variants have been associated with host susceptibility to infectious diseases, including tuberculosis.
Based upon the importance of IFN-γ in protective immunity against Mycobacterium tuberculosis, and the functional role of the IFN-γ + 874T/A single nucleotide polymorphism in IFN-γ production, we genotyped 93 Brazilian
tuberculosis patients and 266 asymptomatic health care workers, including 150 individuals with a positive tuberculin skin
test, and analyzed the possible association of the +874A low IFN-γ producer allele with tuberculosis occurrence. Using multivariable
logistic regression models, genotype and allele frequencies of the mutant + 874A (low IFN-γ producer) allele were significantly
associated with tuberculosis disease. Heterozygous carriers had a 25% increased chance, while individuals presenting the A/A
homozygous genotype had an over two-fold risk of having active tuberculosis (95% CI, 1.16–5.91, P = 0.03). Despite the mixed ethnicity observed in Brazilian populations, the present data agree with observations reported
in other populations and thus demonstrate that the functional +874T/A IFN-γ gene polymorphism is associated with tuberculosis
in different populations. 相似文献
103.
Susana Braz-Mota Luciana Mara Lopes Fé Frederico Augusto Cariello Delunardo Helen Sadauskas-Henrique Vera Maria Fonseca de Almeida-Val Adalberto Luis Val 《Hydrobiologia》2017,789(1):157-166
Hoplosternum littorale is an Amazon fish that lives in urban areas surrounded by polluted igarapés, where elevated copper concentrations eventually occur. The central goal of this study was to evaluate the associated effects of high temperature and copper contamination on survival time and biochemical responses of the Amazonian fish species H. littorale. We exposed fish to two nominal dissolved copper concentrations (50 and 500 µg l?1) and combined temperatures of 28 and 34°C. Our findings showed that the combination of these variables affects the survival time of this species. The activity of the biotransformation enzymes ethoxyresorufin-O-deethylase and glutathione-S-transferase showed no alterations in fish within all treatments. The increase of reactive oxygen species and the decrease in potential total antioxidant capacity promoted the imbalance in the antioxidant system. An induction in superoxide dismutase activity occurred in fish exposed to copper concentrations of 50 and 500 µg l?1 at both temperatures, suggesting liver impairments. Thus, we suggest that H. littorale is sensitive to copper, and this sensitivity is increased further with exposure to high temperatures, particularly in the survival time and reactive oxygen species formation of this fish species. 相似文献
104.
105.
UV induces nucleolar translocation of ING1 through two distinct nucleolar targeting sequences 总被引:13,自引:0,他引:13
Scott M Boisvert FM Vieyra D Johnston RN Bazett-Jones DP Riabowol K 《Nucleic acids research》2001,29(10):2052-2058
The ING1 candidate tumor suppressor is downregulated in a variety of primary tumors and established cancer cell lines. Blocking its expression experimentally promotes unregulated growth in vitro and in vivo, using cell and animal models. Alternative splicing products encode proteins that localize to the nucleus, inhibit cell cycle progression and affect apoptosis in different model systems. Here we show that ING1 proteins translocate to the nucleolus 12–48 h after UV-induced DNA damage. When a small 50 amino acid portion of ING1 was fused to green fluorescent protein, the fusion protein was efficiently targeted to the nucleolus, indicating that ING1 possesses an intrinsic nucleolar targeting sequence (NTS). We mapped this activity to two distinct 4 amino acid regions, which individually direct fused heterologous proteins to the nucleolus. Overexpression of ING1 induced apoptosis of primary fibroblasts in the presence and absence of UV exposure. In contrast, NTS mutants of ING1 that were not targeted to the nucleolus did not efficiently induce apoptosis when overexpressed and instead protected cells from UV-induced apoptosis. Taken together, these results indicate that UV induces ING1 to translocate to the nucleolus and that this translocation may facilitate apoptosis. 相似文献
106.
A growing number of electrochemical technologies depend on fluid flow, and often that fluid is opaque. Measuring the flow of an opaque fluid is inherently more difficult than measuring the flow of a transparent fluid, since optical methods are not applicable. Ultrasound can be used to measure the velocity of an opaque fluid, not only at isolated points, but at hundreds or thousands of points arrayed along lines, with good temporal resolution. When applied to a liquid metal electrode, ultrasound velocimetry involves additional challenges: high temperature, chemical activity, and electrical conductivity. Here we describe the experimental apparatus and methods that overcome these challenges and allow the measurement of flow in a liquid metal electrode, as it conducts current, at operating temperature. Temperature is regulated within ±2 °C using a Proportional-Integral-Derivative (PID) controller that powers a custom-built furnace. Chemical activity is managed by choosing vessel materials carefully and enclosing the experimental setup in an argon-filled glovebox. Finally, unintended electrical paths are carefully prevented. An automated system logs control settings and experimental measurements, using hardware trigger signals to synchronize devices. This apparatus and these methods can produce measurements that are impossible with other techniques, and allow optimization and control of electrochemical technologies like liquid metal batteries. 相似文献
107.
108.
Giovanni Candiano Rosanna Gusmano Paola Altieri Roberta Bertelli Fabrizio Ginevri Domenico A. Coviello Adalberto Sessa Gianluca Caridi Gian Marco Ghiggeri 《Virchows Archiv. B, Cell pathology including molecular pathology》1993,63(1):1-9
Cells from the cysts of patients with autosomal dominant polycystic kidney disease (PKD) were grown in vitro under standard
conditions without the aid of collagen-pretreated surfaces, and both the synthesis and composition of the extracellular matrix
were investigated. At confluence, PKD cells presented the typical features of epithelial cells, but showed a different collagen
composition from fibroblasts. Compared with normal tubular epithelia (NTE), PKD monolayers produced an excess of extracellular
matrix, which accounted for 30% of the total incorporation of [3H] proline, although this value was considerably lower (by a factor of 10) in the case of NTE. Immunohistochemical and electrophoretic
techniques revealed a complex collagen composition in the extracellular matrix which included [α(III)]3 and collagen IV. However, part of the collagen components remained unidentified in spite of the fact that they exhibited
a typical Mr of α1(I) and α2(I) in the presence of urea. Immunoprecipitation with monospecific antibodies and Northern blotting with specific probes failed
to recognize α1(I) and α2(I), but demonstrated their presence in fibroblasts. Purification and cyanogen bromide digestion demonstrated a strong interhomology
in fingerprint peptide composition among the uncharacterized collagens synthesized by PKD cells, thus suggesting a common
identity. These observations document a markedly augmented production of extracellular matrix by PKD cultured cells in vitro,
and show the presence of collagens which do not share homologies with the major collagen molecules. A better characterization
of extracellular matrix composition is central to any comprehension of the cystogenetic mechanisms in vivo. 相似文献
109.
Thomas J. Lloyd Ubirajara Oliveira Britaldo S. Soares-Filho Richard A. Fuller Nathalie Butt John S. Ascher João Paulo Peixoto Pena Barbosa João Aguiar Nogueira Batista Antonio D. Brescovit Claudio J. B. de Carvalho Paulo De Marco Viviane Gianluppi Ferro Felipe Sá Fortes Leite Peter Löwenberg-Neto Adriano Pereira Paglia Daniella Teixeira de Rezende Adalberto J. Santos Daniel Paiva Silva Marcelo Ferreira de Vasconcelos Laura J. Sonter 《Diversity & distributions》2023,29(9):1190-1204
Aim
Mining is increasingly pressuring areas of critical importance for biodiversity conservation, such as the Brazilian Amazon. Biodiversity data are limited in the tropics, restricting the scope for risks to be appropriately estimated before mineral licensing decisions are made. As the distributions and range sizes of other taxa differ markedly from those of vertebrates—the common proxy for analysis of risk to biodiversity from mining—whether mining threatens lesser-studied taxonomic groups differentially at a regional scale is unclear.Location
Brazilian Amazon.Methods
We assess risks to several facets of biodiversity from industrial mining by comparing mining areas (within 70 km of an active mining lease) and areas unaffected by mining, employing species richness, species endemism, phylogenetic diversity and phylogenetic endemism metrics calculated for angiosperms, arthropods and vertebrates.Results
Mining areas contained higher densities of species occurrence records than the unaffected landscape, and we accounted for this sampling bias in our analyses. None of the four biodiversity metrics differed between mining and nonmining areas for vertebrates. For arthropods, species endemism was greater in mined areas. Mined areas also had greater angiosperm species richness, phylogenetic diversity and phylogenetic endemism, although less species endemism than unmined areas.Main Conclusions
Unlike for vertebrates, facets of angiosperm and arthropod diversity are relatively higher in areas of mining activity, underscoring the need to consider multiple taxonomic groups and biodiversity facets when assessing risk and evaluating management options for mining threats. Particularly concerning is the proximity of mining to areas supporting deep evolutionary history, which may be impossible to recover or replace. As pressures to expand mining in the Amazon grow, impact assessments with broader taxonomic reach and metric focus will be vital to conserving biodiversity in mining regions. 相似文献110.
Valverde RH Tortelote GG Lemos T Mintz E Vieyra A 《The Journal of biological chemistry》2005,280(34):30611-30618
The aim of this study was to investigate (a) whether Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) participates in the regulation of plasma membrane Ca2+-ATPase and (b) its possible cross-talk with other kinase-mediated modulatory pathways of the pump. Using isolated innervated membranes of the electrocytes from Electrophorus electricus L., we found that stimulation of endogenous protein kinase A (PKA) strongly phosphorylated membrane-bound CaM kinase II with simultaneous substantial activation of the Ca2+ pump (approximately 2-fold). The addition of cAMP (5-50 pM), forskolin (10 nM), or cholera toxin (10 or 100 nM) stimulated both CaM kinase II phosphorylation and Ca2+-ATPase activity, whereas these activation processes were cancelled by an inhibitor of the PKA alpha-catalytic subunit. When CaM kinase II was blocked by its specific inhibitor KN-93, the Ca2+-ATPase activity decreased to the levels measured in the absence of calmodulin; the unusually high Ca2+ affinity dropped 2-fold; and the PKA-mediated stimulation of Ca2+-ATPase was no longer seen. Hydroxylamine-resistant phosphorylation of the Ca2+-ATPase strongly increased when the PKA pathway was activated, and this phosphorylation was suppressed by inhibition of CaM kinase II. We conclude that CaM kinase II is an intermediate in a complex regulatory network of the electrocyte Ca2+ pump, which also involves calmodulin and PKA. 相似文献