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排序方式: 共有213条查询结果,搜索用时 265 毫秒
171.
Alemasova Elizaveta E. Naumenko Konstantin N. Sukhanova Maria V. Lavrik Olga I. 《Biochemistry. Biokhimii?a》2022,87(1):S32-S47
Biochemistry (Moscow) - Poly(ADP-ribosyl)ation is a post-translational modification of proteins that performs an essential regulatory function in the cellular response to DNA damage. The key enzyme... 相似文献
172.
Many populations live in ‘advective’ media, such as rivers, where flow is biased in one direction. In these environments,
populations face the possibility of extinction by being washed out of the system, even if the net reproductive rate (R) is greater than one. We propose a formal condition for population persistence in advective systems: a population can persist at any location in a homogeneous habitat if and only if it can invade upstream. This leads to a remarkably simple recipe for calculating the minimal value for the net reproductive rate for population
persistence. We apply this criterion to discrete-time models of a semelparous population where dispersal is characterized
by a mechanistically derived kernel. We demonstrate that persistence depends strongly on the form of the kernel’s ‘tail’,
a result consistent with previous literature on the speed of spread of invasions. We apply our theory to models of stream
invertebrates with a biphasic life cycle, and relate our results to the ‘colonization cycle’ hypothesis where bias in downstream
drift is offset by upstream bias in adult dispersal. In the absence of bias in adult dispersal, variability in the duration
of the larval stage and in oviposition sites have a large effect of the persistence condition. The minimization calculations
required in our approach are very straightforward, indicating the feasibility of future applications to life history theory. 相似文献
173.
Nikolay A. Chernyh Andrey V. Mardanov Vadim M. Gumerov Margarita L. Miroshnichenko Alexander V. Lebedinsky Alexander Y. Merkel Douglas Crowe Nikolay V. Pimenov Igor I. Rusanov Nikolay V. Ravin Mary Ann Moran Elizaveta A. Bonch-Osmolovskaya 《Extremophiles : life under extreme conditions》2015,19(6):1157-1171
174.
Cilius Esmann Fonvig Elizaveta Chabanova Ehm Astrid Andersson Johanne Dam Ohrt Oluf Pedersen Torben Hansen Henrik S. Thomsen Jens-Christian Holm 《PloS one》2015,10(8)
Objectives
This cross sectional study aims to investigate the associations between ectopic lipid accumulation in liver and skeletal muscle and biochemical measures, estimates of insulin resistance, anthropometry, and blood pressure in lean and overweight/obese children.Methods
Fasting plasma glucose, serum lipids, serum insulin, and expressions of insulin resistance, anthropometry, blood pressure, and magnetic resonance spectroscopy of liver and muscle fat were obtained in 327 Danish children and adolescents aged 8–18 years.Results
In 287 overweight/obese children, the prevalences of hepatic and muscular steatosis were 31% and 68%, respectively, whereas the prevalences in 40 lean children were 3% and 10%, respectively. A multiple regression analysis adjusted for age, sex, body mass index z-score (BMI SDS), and pubertal development showed that the OR of exhibiting dyslipidemia was 4.2 (95%CI: [1.8; 10.2], p = 0.0009) when hepatic steatosis was present. Comparing the simultaneous presence of hepatic and muscular steatosis with no presence of steatosis, the OR of exhibiting dyslipidemia was 5.8 (95%CI: [2.0; 18.6], p = 0.002). No significant associations between muscle fat and dyslipidemia, impaired fasting glucose, or blood pressure were observed.Liver and muscle fat, adjusted for age, sex, BMI SDS, and pubertal development, associated to BMI SDS and glycosylated hemoglobin, while only liver fat associated to visceral and subcutaneous adipose tissue and intramyocellular lipid associated inversely to high density lipoprotein cholesterol.Conclusion
Hepatic steatosis is associated with dyslipidemia and liver and muscle fat depositions are linked to obesity-related metabolic dysfunctions, especially glycosylated hemoglobin, in children and adolescents, which suggest an increased cardiovascular disease risk. 相似文献175.
Fikadu G. Tafesse Ali Rashidfarrokhi Florian I. Schmidt Elizaveta Freinkman Stephanie Dougan Michael Dougan Alexandre Esteban Takeshi Maruyama Karin Strijbis Hidde L. Ploegh 《PLoS pathogens》2015,11(10)
The ability of phagocytes to clear pathogens is an essential attribute of the innate immune response. The role of signaling lipid molecules such as phosphoinositides is well established, but the role of membrane sphingolipids in phagocytosis is largely unknown. Using a genetic approach and small molecule inhibitors, we show that phagocytosis of Candida albicans requires an intact sphingolipid biosynthetic pathway. Blockade of serine-palmitoyltransferase (SPT) and ceramide synthase-enzymes involved in sphingolipid biosynthesis- by myriocin and fumonisin B1, respectively, impaired phagocytosis by phagocytes. We used CRISPR/Cas9-mediated genome editing to generate Sptlc2-deficient DC2.4 dendritic cells, which lack serine palmitoyl transferase activity. Sptlc2-/- DC2.4 cells exhibited a stark defect in phagocytosis, were unable to bind fungal particles and failed to form a normal phagocytic cup to engulf C. albicans. Supplementing the growth media with GM1, the major ganglioside present at the cell surface, restored phagocytic activity of Sptlc2-/- DC2.4 cells. While overall membrane trafficking and endocytic pathways remained functional, Sptlc2-/- DC2.4 cells express reduced levels of the pattern recognition receptors Dectin-1 and TLR2 at the cell surface. Consistent with the in vitro data, compromised sphingolipid biosynthesis in mice sensitizes the animal to C. albicans infection. Sphingolipid biosynthesis is therefore critical for phagocytosis and in vivo clearance of C. albicans. 相似文献
176.
Novitskaya Ludmila L. Tarelkina Tatiana V. Galibina Natalia A. Moshchenskaya Yulia L. Nikolaeva Nadezhda N. Nikerova Kseniya M. Podgornaya Marina N. Sofronova Irina N. Semenova Ludmila I. 《Journal of Plant Growth Regulation》2020,39(1):378-394
Journal of Plant Growth Regulation - Figured wood of Karelian birch (Betula pendula Roth var. carelica (Merckl.) Hämet-Ahti) is highly appraised for its ornamental properties. The reasons for... 相似文献
177.
Olga P. Gavrilova Aleksandra S. Orina Elizaveta D. Kessenikh Lyudmila K. Gustyleva Elena I. Savelieva Nadezhda N. Gogina Tatiana Yu. Gagkaeva 《化学与生物多样性》2020,17(8)
The biological characterization of Microdochium majus, M. nivale, and M. seminicola strains with wide geographical origins showed the diversity of their pathogenic properties and metabolite compounds, allowing them to exist in their habitats. Significant differences in the ability of Microdochium fungi to cause lesions on wheat and oat leaves were found. The intensity of symptoms depended on the species and substrate origin of the strains. On average M. seminicola strains were able to cause less leaf necrosis than M. majus and M. nivale. The volatile organic compound (VOC) profile of Microdochium fungi included 29 putative fungal metabolites. The spectrum of the identified VOCs in M. seminicola strains was much richer than that in M. majus and M. nivale strains. In addition, the strains of M. seminicola emitted at least six sesquiterpenes. Mycotoxin analysis by HPLC/MS/MS revealed that the analyzed Microdochium strains did not produce any toxic metabolites typically produced by filamentous fungi. 相似文献
178.
Mardanov AV Gumerov VM Beletsky AV Perevalova AA Karpov GA Bonch-Osmolovskaya EA Ravin NV 《Extremophiles : life under extreme conditions》2011,15(3):365-372
The thermoacidophilic microbial community inhabiting the groundwater with pH 4.0 and temperature 50°C at the East Thermal
Field of Uzon Caldera, Kamchatka, was examined using pyrosequencing of the V3 region of the 16S rRNA gene. Bacteria comprise
about 30% of microorganisms and are represented primarily by aerobic lithoautotrophs using the energy sources of volcanic
origin—thermoacidophilic methanotrophs of the phylum Verrucomicrobia and Acidithiobacillus spp. oxidising metals and reduced sulfur compounds. More than 70% of microbial population in this habitat were represented
by archaea, in majority affiliated with “uncultured” lineages. The most numerous group (39% of all archaea) represented a
novel division in the phylum Euryarchaeota related to the order Thermoplasmatales. Another abundant group (33% of all archaea) was related to MCG1 lineage of the phylum Crenarchaeota, originally detected in the Yellowstone hot spring as the environmental clone pJP89. The organisms belonging to these two
groups are widely spread in hydrothermal environments worldwide. These data indicate an important environmental role of these
two archaeal groups and should stimulate the investigation of their metabolism by cultivation or metagenomic approaches. 相似文献
179.
Buhrman G O'Connor C Zerbe B Kearney BM Napoleon R Kovrigina EA Vajda S Kozakov D Kovrigin EL Mattos C 《Journal of molecular biology》2011,413(4):773-789
We have recently discovered an allosteric switch in Ras, bringing an additional level of complexity to this GTPase whose mutants are involved in nearly 30% of cancers. Upon activation of the allosteric switch, there is a shift in helix 3/loop 7 associated with a disorder to order transition in the active site. Here, we use a combination of multiple solvent crystal structures and computational solvent mapping (FTMap) to determine binding site hot spots in the “off” and “on” allosteric states of the GTP-bound form of H-Ras. Thirteen sites are revealed, expanding possible target sites for ligand binding well beyond the active site. Comparison of FTMaps for the H and K isoforms reveals essentially identical hot spots. Furthermore, using NMR measurements of spin relaxation, we determined that K-Ras exhibits global conformational dynamics very similar to those we previously reported for H-Ras. We thus hypothesize that the global conformational rearrangement serves as a mechanism for allosteric coupling between the effector interface and remote hot spots in all Ras isoforms. At least with respect to the binding sites involving the G domain, H-Ras is an excellent model for K-Ras and probably N-Ras as well. Ras has so far been elusive as a target for drug design. The present work identifies various unexplored hot spots throughout the entire surface of Ras, extending the focus from the disordered active site to well-ordered locations that should be easier to target. 相似文献
180.
Patchiness is a defining characteristic of most natural and anthropogenic habitats, yet much of our understanding of how invasions spread has come from models of spatially homogeneous environments. Except for populations with Allee effects, an invader's growth rate when rare and dispersal determine its spread velocity; intraspecific competition has little to no influence. How this result might change with landscape patchiness, however, is poorly understood. We used simulation models and their analytical approximations to explore the effect of density dependence on the spread of annual plant invaders moving through heterogeneous landscapes with gaps in suitable habitat. We found that landscape patchiness and discrete invader population size interacted to generate a strong role for density dependence. Intraspecific competition greatly slowed the spread of invasions through patchy landscapes by regulating how rapidly a population could produce enough seeds to surpass habitat gaps. Populations with continuously varying density showed no such effect of density dependence. We adapted a stochastic dispersal model to approximate spread when gap sizes were small relative to the mean dispersal distance and a Markov chain approximation for landscapes with large gaps. Our work suggests that ecologists must consider reproduction at both low and high densities when predicting invader spread. 相似文献