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91.
JELTE ROZEMA STEF WEIJERS ROB BROEKMAN PETER BLOKKER BERT BUIZER CHANTAL WERLEMAN HASSAN EL YAQINE HANNEKE HOOGEDOORN MIGUEL MAYORAL FUERTES ELISABETH COOPER† 《Global Change Biology》2009,15(7):1703-1715
Annual growth of the polar evergreen shrub Cassiope tetragona on Svalbard was evaluated as a proxy for Arctic summer temperatures. Transfer functions were derived from temperature‐growth correlations of shoots and from a temperature‐growth response, obtained from experimental warming using open top chambers (OTC) in high Arctic tundra vegetation at Isdammen approximately 1.5 km southeast of Longyearbyen, Svalbard (78°N, 15 E) and in Longyeardalen, 3 km west of Isdammen from 2004 to 2006. Air temperatures, monitored throughout the summer months, were 1.3 °C higher inside the OTCs than in the control plots. Annual stem growth was measured by tagging stems and leaves, and in the lab with shoots harvested from OTCs and control plots. Annual growth parameters assessed were leaf production, sum of length and weight of individual leaves, and stem length increment derived from leaf scar distances and the distances between wintermarksepta in the stem. Wintermarksepta are formed at the end of the summer growth period when the pith is narrowing and consist of dense and dark tissue ( Fig. 1b ). The variation of annual growth in a 34‐year site chronology (based on Cassiope shoots from the surroundings of the OTCs and control plots) correlated strongly with the mean summer temperature on Svalbard. The number of leaf pairs, leaf length and stem length also increased in the OTC warmed plots in the second and third year of warming. Transfer functions were derived from the temperature‐annual growth correlations from a single shoot from Longyeardalen, from the cross‐dated Isdammen site chronology and from the growth response to experimental warming. Based on leaf scar distances and distances between wintermarksepta of well‐preserved subfossil shoots in arctic tundra soil, annual stem length increase was assessed for the layers of a soil core collected at the Isdammen site. Based on the derived transfer functions summer temperature of the period relating to the 15 cm deep tundra soil core layer, radiocarbon dated at 4230±40 bp , may have been 3.0 °C lower than the present‐day 6.2 °C value. These results indicate that the transfer functions can be used to reconstruct past temperatures, beyond the time range of instrumental temperature and ice core records of Svalbard.
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94.
Voltage-dependent anion channel (VDAC) as mitochondrial governator--thinking outside the box 总被引:8,自引:0,他引:8
Despite a detailed understanding of their metabolism, mitochondria often behave anomalously. In particular, global suppression of mitochondrial metabolism and metabolite exchange occurs in apoptosis, ischemia and anoxia, cytopathic hypoxia of sepsis and multiple organ failure, alcoholic liver disease, aerobic glycolysis in cancer cells (Warburg effect) and unstimulated pancreatic beta cells. Here, we propose that closure of voltage-dependent anion channels (VDAC) in the mitochondrial outer membrane accounts for global mitochondrial suppression. In anoxia, cytopathic hypoxia and ethanol treatment, reactive oxygen and nitrogen species, cytokines, kinase cascades and increased NADH act to inhibit VDAC conductance and promote selective oxidation of membrane-permeable respiratory substrates like short chain fatty acids and acetaldehyde. In cancer cells, highly expressed hexokinase binds to and inhibits VDAC to suppress mitochondrial function while stimulating glycolysis, but an escape mechanism intervenes when glucose-6-phosphate accumulates and dissociates hexokinase from VDAC. Similarly, glucokinase binds mitochondria of insulin-secreting beta cells, possibly blocking VDAC and suppressing mitochondrial function. We propose that glucose metabolism leads to glucose-6-phosphate-dependent unbinding of glucokinase, relief of VDAC inhibition, release of ATP from mitochondria and ATP-dependent insulin release. In support of the overall proposal, ethanol treatment of isolated rat hepatocytes inhibited mitochondrial respiration and accessibility to adenylate kinase in the intermembrane space, effects that were overcome by digitonin permeabilization of the outer membrane. Overall, these considerations suggest that VDAC is a dynamic regulator, or governator, of global mitochondrial function both in health and disease. 相似文献
95.
96.
Lemasters JJ Holmuhamedov EL Czerny C Zhong Z Maldonado EN 《Biochimica et biophysica acta》2012,1818(6):1536-1544
Voltage dependent anion channels (VDAC) are highly conserved proteins that are responsible for permeability of the mitochondrial outer membrane to hydrophilic metabolites like ATP, ADP and respiratory substrates. Although previously assumed to remain open, VDAC closure is emerging as an important mechanism for regulation of global mitochondrial metabolism in apoptotic cells and also in cells that are not dying. During hepatic ethanol oxidation to acetaldehyde, VDAC closure suppresses exchange of mitochondrial metabolites, resulting in inhibition of ureagenesis. In vivo, VDAC closure after ethanol occurs coordinately with mitochondrial uncoupling. Since acetaldehyde passes through membranes independently of channels and transporters, VDAC closure and uncoupling together foster selective and more rapid oxidative metabolism of toxic acetaldehyde to nontoxic acetate by mitochondrial aldehyde dehydrogenase. In single reconstituted VDAC, tubulin decreases VDAC conductance, and in HepG2 hepatoma cells, free tubulin negatively modulates mitochondrial membrane potential, an effect enhanced by protein kinase A. Tubulin-dependent closure of VDAC in cancer cells contributes to suppression of mitochondrial metabolism and may underlie the Warburg phenomenon of aerobic glycolysis. This article is part of a Special Issue entitled: VDAC structure, function, and regulation of mitochondrial metabolism. 相似文献
97.
Zahoor Ahmad Ejaz Ahmad Waraich Celaleddin Barutçular Akbar Hossain Murat Erman Fatih ÇIĞ Hany Gharib Ayman EL Sabagh 《Phyton》2020,89(3):529-539
The main objective of the research is to assess the role of foliar application of silicon (Si) for enhancing the survival ability of wheat under drought stress
through improving its morphology, physicochemical and antioxidants activities.
Treatments were five doses of Si at the rate of 2, 4, 6 and 8 mM and a control. After
completion of seeds germination, pots were divided into four distinct groups at various field capacity (FC) levels, such as 100% FC (well-irrigated condition), 75% FC
(slight water deficit), 50% FC (modest water deficit) and 25% FC (severe water deficit stress condition). Foliar application of Si at the rate of 2, 4, 6 and 8 mM and a
control were given after 30 days of sowing at the tillering stage of wheat. Findings
of the present investigation indicated that increasing the level of water deficit stress
reduced the morphological parameters (such as root and shoot fresh and dry-biomass weight) and physico-biochemical events ((such as chlorophyll contents by
estimating SPAD value), total free amino acid (TFAA), total soluble sugar (TSS),
total soluble protein (TSP), total proline (TP), CAT (catalase), POD (peroxidase),
SOD (superoxide dismutase) and APX (ascorbate peroxidase)) of wheat; while
foliar application of Si at 6 mM at tillering stage enhanced the drought tolerance
in wheat by increasing morphology and physiochemical characters under all levels
of drought stress. Similarly, antioxidants activities in wheat also enhanced by the
application of Si at 6 mM under normal as well as all drought stress levels. Therefore, it may be concluded that foliar application of Si at 6 mM at the tillering stage
of wheat is an important indication for increasing the drought tolerance by improving the morphology, physico-biochemical and antioxidants activities in plants under
deficit water (drought) conditions. 相似文献
98.
Alhan Sariyev Celaleddin Barutcular Mert Acar Akbar Hossain Ayman EL Sabagh 《Phyton》2020,89(3):519-528
Maize being sub-tropical crop is sensitive to water deficit during the
early growth stages; particularly clay-rich soil, due to the compaction of the soil.
It is well-documented that potential sub-surface drip irrigation (SDI) (Full irrigation; SDIFull (100% field capacity (FC)), Deficit irrigation; SDIDeficit (70% FC))
improves water use efficiency, which leads to increased crop productivity; since it
has a constraint that SDI excludes soil air around the root-zone during irrigation
events, which alter the root function and crop performance. Additionally, in clayrich soils, the root system of plants generally suffers the limitation of oxygen,
particularly the temporal hypoxia, and occasionally from root anoxia; while
SDI system accomplishes with the aerating stream of irrigation in the rhizosphere
could provide oxygen root environment. The oxygen can be introduced into the
irrigation stream of SDI through two ways: the venturi principle, or by using solutions of hydrogen peroxide through the air injection system. Therefore, the application of hydrogen peroxide (H2O2; HP) can mitigate the adverse effect of soil
compactness and also lead to improving the growth, yield and yield attributes
of maize in clay-rich soil. Considering the burning issue, a field study was conducted in consecutive two seasons of 2017 and 2018; where hybrid maize was
cultivated as a second crop, to evaluate the effect of liquid-injection of H2O2
(HP) into the irrigation stream of SDI on the performance of maize in a clay-rich
soil field of Adana, Turkey. When soil water content decreased in 50% of available water, irrigation was performed. The amount of water applied to reach the
soil water content to the field capacity is SDIFull (100% FC) and 70% FC of this
water is SDIDeficit (70% FC). In the irrigation program, hydrogen peroxide (HP)
was applied at intervals of 7 days on average according to available water with
and without HP: SDIFull (100% FC) + 0 ppm HP with full SDI irrigation;
SDIFull (100% FC) + 250 ppm HP with deficit SDI irrigation; SDIDeficit
(70% FC) + 0 ppm HP, SDIDeficit (70% FC) + 250 ppm HP and SDIDeficit
(70% FC) + 500 ppm HP. Deficit irrigation (SDIDeficit (70% FC)) program
was started from tasseling stage and continued up to the physiological maturity
stage with sub-soil drip irrigation. H2O2 was applied 3 times during the growing season. Two years’ results revealed that the liquid-injection of H2O2 into the irrigation stream of SDI improved the growth and yield-related attributes and grain
yield of maize. Based on the obtained results, during the extreme climatic condition in the year 2017, SDIFull (100% FC) + 250 ppm HP was more effective than
SDIFull (100% FC) + 0 ppm HP on all traits for relative to full irrigation. While,
during the favourable climatic condition in the 2018 season, SDIFull (100% FC)
+ 250 ppm HP was more effective than full irrigation with SDIFull (100% FC) +
0 ppm HP for the grain yield, grains, and SPAD value. Accordingly, the most
effective treatment was SDIFull (100% FC) + 250 ppm HP, as it gave the highest
growth and yield-related attributes and grain yield of maize followed by
SDIDeficit (70% FC) + 250 ppm HP. Therefore, SDIFull with 250 ppm H2O2
using as liquid-injection may be recommended to mitigate the adverse effect of
soil compactness particularly water-deficit stress in clay-rich soil for the sustainability of maize production. 相似文献
99.
Ahmed EL Bedewi Randa Yousef Dalia Abdel Halim Rehab Hegazy William Willis Lisa M. Miller Medhat EL Mofty 《International journal of peptide research and therapeutics》2013,19(3):203-207
Psoriasis vulgaris and, Lichen planus are cutaneous inflammatory conditions that usually exhibit distinctive morphology. Ten psoriasis vulgaris and, ten Lichen planus patients (mean age, 45 ± 10.27 years) with confirmed histopathological diagnoses were analyzed. In the current study synchrotron infrared (IR) microspectroscopy was used to differentiate between these two conditions based on their lymphocytic proteins analyses. It was found that β-sheets protein structure, known to represent cell apoptosis, were expressed significantly in Lichen planus conditions than that of the psoriasis vulgaris when analyzed against the established normal control groups of five patients of comparable age and, genders (P = 0.001, 0.03 respectively). Also, the amide 1 protein type within the epidermis of Lichen planus were expressed in significant proportions as compared to psoriasis vulgaris (P < 0.001). On the contrary, the amide 1 protein structural types were found clustered in psoriasis vulgaris in different IR spectra than that in Lichen planus as observed in a number of patients during this study. These observations indicated that the concentration of amide 1 protein in psoriasis vulgaris varies to that of Lichen planus. In conclusion, both psoriasis vulgaris and, Lichen planus have different types of epidermal and, dermal protein structures and, this information can be of clinical diagnostic and therapeutic use for these cutaneous inflammatory conditions in near future. 相似文献
100.
Hugo Roume Emilie EL Muller Thekla Cordes Jenny Renaut Karsten Hiller Paul Wilmes 《The ISME journal》2013,7(1):110-121
Mixed microbial communities are complex, dynamic and heterogeneous. It is therefore essential that biomolecular fractions obtained for high-throughput omic analyses are representative of single samples to facilitate meaningful data integration, analysis and modeling. We have developed a new methodological framework for the reproducible isolation of high-quality genomic DNA, large and small RNA, proteins, and polar and non-polar metabolites from single unique mixed microbial community samples. The methodology is based around reproducible cryogenic sample preservation and cell lysis. Metabolites are extracted first using organic solvents, followed by the sequential isolation of nucleic acids and proteins using chromatographic spin columns. The methodology was validated by comparison to traditional dedicated and simultaneous biomolecular isolation methods. To prove the broad applicability of the methodology, we applied it to microbial consortia of biotechnological, environmental and biomedical research interest. The developed methodological framework lays the foundation for standardized molecular eco-systematic studies on a range of different microbial communities in the future. 相似文献