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671.
Yu-Shik Hwang Yunyi Kang Athanasios Mantalaris 《Biotechnology and Bioprocess Engineering》2007,12(1):15-21
Regeneration of skeletal tissues is among the most promising areas of biological repair, providing a broad spectrum of potential
clinical applications. In view of the ageing population and the worldwide shortage of donor tissue, tissue engineering is
expected to become a major contributor to modern medicine. Recently, embryonic stem cells (ESCs) have received extensive attention
due to their distinct biological properties, namely their unlimited self-renewal capacity and their pluripotency, which have
rendered them a potent cell source for various medical and tissue engineering applications. The application of embryonic stem
cells to skeletal tissue engineering requires inducing thein vitro differentiation of ESCs into the osteogenic and chondrogenic lineages. Although considerable progress has been made in directing
embryonic stem cell differentiation towards the osteogenic and chondrogenic lineages, there are still obstacles remaining
that need to be resolved before ESCs can be used as a suitable cell source in cell and tissue therapies. In particular, the
efficient differentiation of ESCsin vitro towards the desired lineage requires the development of well-defined and proficient protocols, which would reduce the likelihood
of spontaneous differentiation into divergent lineages and increase the available cell source for application to bone and
cartilage tissue engineering therapies. Herein, this review provides a critical examination of the various experimental strategies
that could be used to direct the differentiation of ESCs towards the skeletal tissuein vitro, especially the osteogenic and chondrogenic lineasges. 相似文献
672.
It is widely accepted that a healthy diet is an important factor in preventing chronic diseases, and in improving energy balance
and weight management. Studies have shown strong inverse correlations between tomato consumption and the risk of certain types
of cancer, cardiovascular diseases and age-related macular degeneration. Because tomato is the second-most important vegetable
in the world after potato, this horticultural crop constitutes an excellent source of health-promoting compounds due to the
balanced mixture of minerals and antioxidants including vitamins C and E, lycopene, β-carotene, lutein and flavonoids such
as quercetin. Improvement in phytonutrients in tomatoes can be achieved by cultivar selection, environmental factors, agronomic
practices, stage of ripeness at harvest, and appropriate handling and conditioning all the way from the field to the consumer.
The purpose of this paper is to review the recent literature of the main factors that can improve the nutritional quality
of tomato and consequently their beneficial role in human diet. The importance of genotype selection and the optimization
of environmental conditions (light, temperature, humidity, atmospheric CO2 and air pollutants) for high nutritional value is outlined first, followed by the optimization of agricultural practices
(soil properties, water quality, mineral nutrition, salinity, grafting, pruning, growing systems, growth promoters, maturity,
and mechanical and pest injuries). The review concludes by identifying several prospects for future research such as modelling
and genetic engineering of the nutritional value of tomato. 相似文献
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Amyl nitrite was administered on two occasions to a patient with muscular subaortic stenosis, to ascertain if selective peripheral vasodilatation would affect the degree of obstruction to left ventricular outflow in this condition. On each occasion there was a marked increase in the systolic pressure gradient across the left ventricular outflow tract prior to the onset of reflex tachycardia. Following the second amyl nitrite inhalation, the systolic cross-sectional area of the left ventricular outflow tract decreased to 1.0 sq. cm., from the control value of 2.6 sq. cm. It is believed that the increased degree of muscular subaortic stenosis, following peripheral vasodilatation, could be secondary to a decrease in the systolic size of the whole left ventricle, or to a selective decrease in the physical size of the left ventricular outflow tract. 相似文献
676.
Maria Lazarina Stefanos P. Sgardelis Thomas Tscheulin Jelle Devalez Vangelis Mizerakis Athanasios S. Kallimanis Spyridon Papakonstantinou Thanassis Kyriazis Theodora Petanidou 《Biodiversity and Conservation》2017,26(1):115-131
Fire affects diversity and structure of flower-visitor communities. We explored the effect of fire history on the diversity patterns and structure of the flower-visitor guilds (bees, beetles, flies, sawflies, and wasps), across a post-fire regeneration sequence of pine forests in Rhodes Island, Greece. Fire history was defined by fire frequency and post-fire age of sites. We did not find significant differences in species richness and abundance per guild between fire-history regimes except for the abundance of flies, sawflies and the entire flower-visitor community. Fire strongly affected the community structure of bees, beetles, and sawflies. Some of the most abundant and common species responded significantly to fire in terms of abundance; yet, we observed no significant variation in the abundance of the common species of bees, the most prominent pollinator group, implying that provision of pollination services may not be considerably affected by fire. Long-unburnt sites displayed higher heterogeneity in species composition compared to recently-burnt sites (either burnt once or twice). This pattern deviated significantly from null expectations when analyzing the abundance-based metric of β-diversity and was obscure in the case of the presence/absence-based metric, indicating that fire affected mainly the spatial distribution of individuals, i.e. the main change is not due to species turnover but to changes in relative abundance. Furthermore, the species composition in recently-burnt sites (burnt once in 2008) were more similar than in twice-burnt sites (including areas burnt once between 1984 and 1992, and in 2008), indicating that fire frequency affected post-fire heterogeneity of species composition. 相似文献
677.
Benjamin Strain James Morrissey Athanasios Antonakoudis Cleo Kontoravdi 《Biotechnology and bioengineering》2023,120(9):2460-2478
Genome-scale metabolic models (GEMs) possess the power to revolutionize bioprocess and cell line engineering workflows thanks to their ability to predict and understand whole-cell metabolism in silico. Despite this potential, it is currently unclear how accurately GEMs can capture both intracellular metabolic states and extracellular phenotypes. Here, we investigate this knowledge gap to determine the reliability of current Chinese hamster ovary (CHO) cell metabolic models. We introduce a new GEM, iCHO2441, and create CHO-S and CHO-K1 specific GEMs. These are compared against iCHO1766, iCHO2048, and iCHO2291. Model predictions are assessed via comparison with experimentally measured growth rates, gene essentialities, amino acid auxotrophies, and 13C intracellular reaction rates. Our results highlight that all CHO cell models are able to capture extracellular phenotypes and intracellular fluxes, with the updated GEM outperforming the original CHO cell GEM. Cell line-specific models were able to better capture extracellular phenotypes but failed to improve intracellular reaction rate predictions in this case. Ultimately, this work provides an updated CHO cell GEM to the community and lays a foundation for the development and assessment of next-generation flux analysis techniques, highlighting areas for model improvements. 相似文献
678.
679.
Héctor Martínez Ávila Silke Schwarz Eva-Maria Feldmann Athanasios Mantas Achim von Bomhard Paul Gatenholm Nicole Rotter 《Applied microbiology and biotechnology》2014,98(17):7423-7435
Bacterial nanocellulose (BNC), synthesized by the bacterium Gluconacetobacter xylinus, is composed of highly hydrated fibrils (99 % water) with high mechanical strength. These exceptional material properties make BNC a novel biomaterial for many potential medical and tissue engineering applications. Recently, BNC with cellulose content of 15 % has been proposed as an implant material for auricular cartilage replacement, since it matches the mechanical requirements of human auricular cartilage. This study investigates the biocompatibility of BNC with increased cellulose content (17 %) to evaluate its response in vitro and in vivo. Cylindrical BNC structures (Ø48?×?20 mm) were produced, purified in a built-in house perfusion system, and compressed to increase the cellulose content in BNC hydrogels. The reduction of endotoxicity of the material was quantified by bacterial endotoxin analysis throughout the purification process. Afterward, the biocompatibility of the purified BNC hydrogels with cellulose content of 17 % was assessed in vitro and in vivo, according to standards set forth in ISO 10993. The endotoxin content in non-purified BNC (2,390 endotoxin units (EU)/ml) was reduced to 0.10 EU/ml after the purification process, level well below the endotoxin threshold set for medical devices. Furthermore, the biocompatibility tests demonstrated that densified BNC hydrogels are non-cytotoxic and cause a minimal foreign body response. In support with our previous findings, this study concludes that BNC with increased cellulose content of 17 % is a promising non-resorbable biomaterial for auricular cartilage tissue engineering, due to its similarity with auricular cartilage in terms of mechanical strength and host tissue response. 相似文献
680.
Christina Piperi Elena Farmaki Fotis Vlastos Athanasios G. Papavassiliou Nadine Martinet 《Journal of biomolecular techniques》2008,19(5):281-284
Epigenetic changes, or heritable alterations in gene function that do not affect DNA sequence, are rapidly gaining acceptance as co-conspirators in carcinogenesis. Although DNA methylation signature analysis by methylation-specific polymerase chain reaction has been a breakthrough method in speed and sensitivity for gene methylation studies, several factors still limit its application as a routine diagnostic and prognostic test. 相似文献