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63.
Juan Guevara Jr. E. Timothy Walch Henry F. Epstein James T. Sparrow Antonio M. Gotto Natalia V. Valentinova 《The protein journal》1995,14(7):627-631
Protein-tyrosine kinases of signal transduction pathways occur and function intracellularly. In contrast, the low-density lipoprotein (LDL) particle circulates in plasma, where its function is to solubilize and transport lipid. Recently, several reports showed that LDL may have a role in signal transduction. We have identified a region in the apoB-100 primary structure which shows similarity to Src-homology-1 (SH1) domains, the kinase region of protein-tyrosine kinases. Results obtained in protein kinase assays of highly purified LDL showed that only the apoB-100 was phosphorylated, suggesting that apoB-100 has the capacity to undergo autophosphorylation like known protein-tyrosine kinases. Phosphorylation was not observed for any other apolipoprotein in LDL or for any component of high-density lipoprotein and lipoprotein [a]. Our results suggest that apoB-100 may be a novel and functional member of thesrc protein kinase family. 相似文献
64.
Correlative ecological niche models are increasingly used to estimate potential distributions during the Last Glacial Maximum (LGM) for biogeographical research. In the case of presence‐background/pseudoabsences techniques, cold environments that are poorly represented in existing geography can complicate the process of model calibration and transfer into more extreme cold environments that were very common during the LGM (non‐analog conditions). This may lead to biologically unrealistic estimations. Using one cold‐adapted North American mammal, we explore a real scenario to better understand the effect of restricting the range of environmental conditions over which niche models are calibrated and then transferred to LGM conditions. We performed two sets of experiments in Maxent: 1) we calibrated models in the context of only present‐day climate conditions, which is the most common practice, and compared predictions under LGM conditions based on two extrapolation methods (clamping versus unconstrained); 2) we calibrated single models using both present‐day and LGM conditions as part of the same background in order to include more extreme environments in the model calibration. Our experiments led to dramatically different estimates of species’ potential distributions, showing notable differences with respect to latitudinal and elevational shifts during the LGM. Models calibrated using present‐day climates yielded biologically unrealistic estimations, suggesting that species survived in the glaciers during the LGM. Even more unrealistic estimations were achieved when clamping was enforced as the method to extrapolate. Models calibrated in the context of both modern and past climates reduced the required degree of extrapolation and allowed more realistic potential distributions, suggesting that the species avoided extremely cold conditions during the LGM. This study alerts to the possibility of obtaining implausible potential distributions during the LGM due to restricted background datasets and offers recommendations that should promote better strategies to estimate distributional changes during glaciations. 相似文献
65.
Guevara R Santandreu FM Valle A Gianotti M Oliver J Roca P 《Free radical biology & medicine》2009,46(2):169-175
Females show lower incidences of several neurodegenerative diseases related to oxidative stress and mitochondrial dysfunction than males. In addition, female rats show more differentiated mitochondria than males in several tissues. The aim of this work was to investigate the existence of sex-dependent differences in brain mitochondrial bioenergetics and oxidative balance in aged rats. Results showed that aged female rat brain had a lower mitochondria content than aged male brain but with a greater differentiation degree given the higher mitochondrial protein content and mitochondrial complex activities in females. Female rat brain also showed a better oxidative balance than that of males, reflected by the fact that higher mitochondrial respiratory chain function is accompanied by a similar ROS production and greater antioxidant enzyme activities, which could be responsible for the lesser oxidative damage observed in proteins and lipids in this sex. Interestingly, levels of UCP4 and UCP5--proteins related to a decrease in ROS production--were also higher in females. In conclusion, aged female rat brain had more differentiated mitochondria than male brain and showed a better control of oxidative stress balance, which could be due, in part, to the neuroprotective effect of UCPs. 相似文献
66.
Díaz A Carro S Santiago L Estévez J Guevara C Blanco M Sánchez L Sánchez L López N Cruz D López R Cuetara EB Fuentes JL 《Genetics and molecular biology》2009,32(2):367-372
The analysis of DNA damage by mean of Comet or single cell gel electrophoresis (SCGE) assay has been commonly used to assess genotoxic impact in aquatic animals being able to detect exposure to low concentrations of contaminants in a wide range of species. The aims of this work were 1) to evaluate the usefulness of the Comet to detect DNA strand breakage in dolphin leukocytes, 2) to use the DNA diffusion assay to determine the amount of DNA strand breakage associated with apoptosis or necrosis, and 3) to determine the proportion of DNA strand breakage that was unrelated to apoptosis and necrosis. Significant intra-individual variation was observed in all of the estimates of DNA damage. DNA strand breakage was overestimated because a considerable amount (~29%) of the DNA damage was derived from apoptosis and necrosis. The remaining DNA damage in dolphin leukocytes was caused by factors unrelated to apoptosis and necrosis. These results indicate that the DNA diffusion assay is a complementary tool that can be used together with the Comet assay to assess DNA damage in bottlenose dolphins. 相似文献
67.
Angel Montero Ovidio Hernando Veronica Caon Diana Guevara Jeannete Valero Xin Chen-Zhao Paz Garcia-Acilu Emilio Sanchez Mercedes Lopez Raquel Ciervide Mariola Garcia-Aranda Beatriz Alvarez Alejandro Prado Rosa Alonso Pedro Fernandez-Leton Carmen Rubio 《Reports of Practical Oncology and Radiotherapy》2021,26(4):605
BackgroundAbout 5% of prostate cancer cases are metastatic at diagnoses. Radiotherapy of both primary tumor and secondary lesions can be, in addition to systemic treatments, a radical alternative for selected patients.Materials and methodsPatients with de novo prostate carcinoma with bone or lymph node metastases were retrospectively reviewed. All patients received moderate hypofractionated IMRT/VMAT up to 63 Gy in 21 daily fractions of 3 Gy to prostate and metastases with neoadjuvant and concurrent androgen deprivation therapy (ADT). According to known advances some patients also received abiraterone, enzalutamide, or docetaxel.ResultsBetween 2015–2020, we attended 26 prostate cancer patients (median age 69.5 years, range 52–84) with simultaneous oligometastases [mean 2.1 metastases, median 1.5 metastases (range 1–6)]. Eighteen patients (69%) presented lymph node metastases, 4 (15.5%) bone metastases and 4 (15.5%) both lymph node and bone metastases. With a median follow-up of 15.5 months (range 3–65 months), 16 patients (62%) are alive and tumor free while 10 (38%) are alive with tumor. Four patients (17%) developed tumor progression, out of irradiated area in all cases, with a median time to progression of 43.5 months (range 27–56 months). Actuarial progression-free survival (PFS) rates at 12 and 24 months were 94.1% and 84.7%, respectively. No grade > 2 acute or late complications were recorded.ConclusionsSimultaneous directed radical hypofractionated radiation therapy for prostate and metastases is feasible, well tolerated and achieves an acceptable PFS rate. However, further studies with longer follow-up are necessary to definitively address these observations. 相似文献
68.
Makoto Ikenaga Rafael Guevara Amanda L. Dean Cristina Pisani Joseph N. Boyer 《Microbial ecology》2010,59(2):284-295
Community structure of sediment bacteria in the Everglades freshwater marsh, fringing mangrove forest, and Florida Bay seagrass
meadows were described based on polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) patterns of 16S
rRNA gene fragments and by sequencing analysis of DGGE bands. The DGGE patterns were correlated with the environmental variables
by means of canonical correspondence analysis. There was no significant trend in the Shannon–Weiner index among the sediment
samples along the salinity gradient. However, cluster analysis based on DGGE patterns revealed that the bacterial community
structure differed according to sites. Not only were these salinity/vegetation regions distinct but the sediment bacteria
communities were consistently different along the gradient from freshwater marsh, mangrove forest, eastern-central Florida
Bay, and western Florida Bay. Actinobacteria- and Bacteroidetes/Chlorobi-like DNA sequences were amplified throughout all sampling sites. More Chloroflexi and members of candidate division WS3 were found in freshwater marsh and mangrove forest sites than in seagrass sites. The
appearance of candidate division OP8-like DNA sequences in mangrove sites distinguished these communities from those of freshwater
marsh. The seagrass sites were characterized by reduced presence of bands belonging to Chloroflexi with increased presence of those bands related to Cyanobacteria, γ-Proteobacteria, Spirochetes, and Planctomycetes. This included the sulfate-reducing bacteria, which are prevalent in marine environments. Clearly, bacterial communities
in the sediment were different along the gradient, which can be explained mainly by the differences in salinity and total
phosphorus. 相似文献
69.
Sebastián Tanco Joan L. Arolas Tibisay Guevara Francesc X. Avilés F. Xavier Gomis-Rüth 《Journal of molecular biology》2010,401(3):465-477
Drosophila melanogaster silver gene is the ortholog of the coding gene of mammalian carboxypeptidase D (CPD). The silver gene gives rise to eight different splicing variants of differing length that can contain up to three homologous repeats. Among the protein variants encoded, the short form 1B alias DmCPD1Bs (D. melanogaster CPD variant 1B short) is necessary and sufficient for viability of the fruit fly. It has one single repeat, it is active against standard peptide substrates, and it is localized to the secretory pathway. In this work, the enzyme was found as a monomer in solution and as a homodimer in the crystal structure, which features a protomer with an N-terminal 311-residue catalytic domain of α/β-hydrolase fold and a C-terminal 84-residue all-β transthyretin-like domain. Overall, DmCPD1Bs conforms to the structure of N/E-type funnelins/M14B metallopeptidases, but it has two unique structural elements potentially involved in regulation of its activity: (i) two contiguous surface cysteines that may become palmitoylated and target the enzyme to membranes, thus providing control through localization, and (ii) a surface hot spot targetable by peptidases that would provide a regulatory mechanism through proteolytic inactivation. Given that the fruit fly possesses orthologs of only two out of the five proteolytically competent N/E-type funnelins found in higher vertebrates, DmCPD1Bs may represent a functional analog of at least one of the missing mammalian CPs. 相似文献
70.
Flores Ramírez F Abreu González M García Delgado C Aparicio Onofre A Guevara Yáñez R Sánchez Urbina R Murguía Peniche T Ramírez-Ortíz MA Ibarra Ríos D Ortiz de Luna RI Cervantes Peredo AB Morán Barroso VF 《Genetic counseling (Geneva, Switzerland)》2010,21(4):363-373
We describe a patient who had multiple malformations including ventriculomegaly, colpocephaly, corpus callosum, cerebellum and vermix hypoplasia, optic nerve hypoplasia, corneal opacity and congenital heart disease in whom a trisomy 1q32-qter and monosomy 5p derived from a t(1;5)mat was diagnosed by karyotype and FISH analysis. This trisomy/monosomy association has not been previously reported. The familial analysis of the translocation was carried out in four generations and its implications on the phenotype of the patient and genetic counseling are discussed. 相似文献