全文获取类型
收费全文 | 509篇 |
免费 | 40篇 |
国内免费 | 1篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 8篇 |
2020年 | 13篇 |
2019年 | 12篇 |
2018年 | 15篇 |
2017年 | 14篇 |
2016年 | 17篇 |
2015年 | 28篇 |
2014年 | 30篇 |
2013年 | 35篇 |
2012年 | 57篇 |
2011年 | 32篇 |
2010年 | 25篇 |
2009年 | 29篇 |
2008年 | 27篇 |
2007年 | 27篇 |
2006年 | 25篇 |
2005年 | 19篇 |
2004年 | 18篇 |
2003年 | 21篇 |
2002年 | 19篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1977年 | 2篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有550条查询结果,搜索用时 15 毫秒
541.
Eliana C. De Benedetti Cintia W. Rivero Claudia N. Britos Mario E. Lozano Jorge A. Trelles 《Biotechnology progress》2012,28(5):1251-1256
An efficient and green bioprocess to obtain 2,6‐diaminopurine nucleosides using thermophilic bacteria is herein reported. Geobacillus stearothermophilus CECT 43 showed a conversion rate of 90 and 83% at 2 h to obtain 2,6‐diaminopurine‐2′‐deoxyriboside and 2,6‐diaminopurine riboside, respectively. The selected biocatalyst was successfully stabilized in an agarose matrix and used to produce up to 23.4 g of 2,6‐diaminopurine‐2′‐deoxyriboside in 240 h of process. These nucleoside analogues can be used as prodrug precursors or in antisense oligonucleotide synthesis. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012 相似文献
542.
543.
In this study a proteomic approach was used to investigate the steady-state response of Escherichia coli to temperature up-shifts in a cascade of two continuously operated bioreactors. The first reactor served as cell source with
optimal settings for microbial growth, while in the second chemostat the cells were exposed to elevated temperatures. By using
this reactor configuration, which has not been reported to be used for the study of bacterial stress responses so far, it
is possible to study temperature stress under well-defined, steady-state conditions. Specifically the effect on the cellular
adaption to temperature stress using two-dimensional gel electrophoresis was examined and compared at the cultivation temperatures
of 37°C and 47.5°C. As expected, the steady-state study with the double bioreactor configuration delivered a different protein
spectrum compared to that obtained with standard batch experiments in shaking flasks and bioreactors. Setting a high cut-out
spot-to-spot size ratio of 5, proteins involved in defence against oxygen stress, functional cell envelope proteins, chaperones
and proteins involved in protein biosynthesis, the energy metabolism and the amino acid biosynthesis were found to be differently
expressed at high cultivation temperatures. The results demonstrate the complexity of the stress response in a steady-state
culture not reported elsewhere to date. 相似文献
544.
Ezequiel José Pérez-Monterroza Ana María Chaux-Gutiérrez Célia Maria Landi Franco Vânia Regina Nicoletti 《Food biophysics》2018,13(4):343-352
Microencapsulation of bixin using high-amylose corn starch was carried out by the acidification method. Bixin powders were characterized by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), FT-IR spectrometry, color parameters, encapsulation efficiency, bixin release profile. In addition, the effect of whey protein (WP) on the microencapsulation process was investigated. The results obtained from DSC, X-ray diffraction and FT-IR spectrometry indicated that only in the samples prepared at 90 °C (B0WP90°C, B10WP90°C, and B20WP90°C) there was formation of crystalline structures, with melting temperatures at 117.2°, 105° and 104 °C, respectively. The possible interactions between bixin, WP and amylose starch are also discussed. 相似文献
545.
Steve Ahlswede Ezequiel Chimbioputo Fabiano Derek Keeping Klaus Birkhofer 《African Journal of Ecology》2019,57(2):177-189
Finding an appropriate method to monitor a wide range of mammal species simultaneously is notoriously difficult, as each method has its limitations. Here, we examine a formula, known as the Formozov–Malyshev–Pereleshin (FMP), which uses mean daily travel distances (day ranges) to convert spoor counts into density estimates. Availability of accurate estimates of day ranges is a limitation of the FMP formula. Here, we used allometry to estimate day ranges for those species that lacked empirical movement data and general additive models (GAM) to assess trends in density estimates. With this approach, we derived density estimates for 10 mammal species, regardless of whether they were abundant, or rare and elusive (e.g. carnivores). General additive models suggest that six species are stable or increasing, and four declining, although all nonsignificantly. Use of allometric estimates in lieu of empirical estimates led to falsely increased precision in density estimates, highlighting the need to fill the knowledge gap in movement ecology for certain species. Simulations were used to examine error introduced into trend estimates by this bias. We conclude that the FMP formula, when properly employed, can be an efficient method for simultaneous monitoring of multispecies in different functional groups. 相似文献
546.
L Goya F Rivero M A Martín C Alvarez S Ramos A de la Puente A M Pascual-Leone 《Life sciences》1999,64(24):2255-2271
To investigate the role played by factors other than GH, such as nutrients and insulin, on IGF-I secretion, adult male rats of 200 g.b.w. were food-restricted for 7 days and then made diabetic by streptozotocin administration (UD). Different groups of UD rats were submitted to the following four day treatments: left untreated (UD), refed (UD+R), treated with insulin (UD+I), or a combination of both refeeding and insulin (UD+R+I). Serum concentration of IGF-I and liver mRNA expression of IGF-I, IGF-binding proteins and GH receptor were measured. Insulin treatment alone partially recovered liver IGF-I and IGFBPs mRNA expression, while refeeding alone had no effect. Only a combination of both insulin and refeeding recovered both parameters. Contrary to the results obtained with a longer period of recovery, these experiments show that serum and mRNA expression of IGF-I and IGFBPs in adult undernourished diabetic rats can be restored by insulin and nutrients administration with no prior restoration of serum and pituitary GH to control values and no compensatory changes in GH receptor gene expression. 相似文献
547.
José Ezequiel Santibañez-Aguilar Gonzalo Guillen-Gosálbez Ricardo Morales-Rodriguez Laureano Jiménez-Esteller Agustín Jaime Castro-Montoya José María Ponce-Ortega 《Bioenergy Research》2016,9(4):1053-1069
Biofuels provide an attractive alternative for satisfying energy demands in a more sustainable way than fossil fuels. To establish a biorefinery, an optimal plan must be implemented for the entire associated supply chain, covering such aspects as selection of feedstocks, location, and capacity of biorefineries, selection of processing technologies, production amounts and transportation flows. In this context, there are several parameters, including the availability of biomass, product demand, and product prices, which are difficult to predict because they might change drastically over the different seasons of the year as well as across years. To address this challenge, this work presents a mathematical programming model for the optimal planning of a distributed system of biorefineries that considers explicitly the uncertainty associated with the supply chain operation as well as the associated risk. The potential of the proposed approach is demonstrated through its application to the production of biofuels in Mexico, considering multiple raw materials and products. 相似文献
548.
F. Alfonso J. Restrepo J. Cuesta T. Bastante F. Rivero A. Benedicto 《Netherlands heart journal》2015,23(5):287-288
A patient presenting with ‘edge’ in-stent restenosis 12 years after the implantation of a bare-metal stent in the mid-left anterior descending coronary artery is described. Optical coherence tomography disclosed the presence of ruptured neoatherosclerosis at the stent edge. The value of this imaging technique to unravel this unique underlying anatomic substrate is discussed. The therapy of choice for patients presenting with edge in-stent restenosis (ISR) is reviewed. 相似文献
549.
550.
Romain Pigeault Julien Vézilier Stéphane Cornet Flore Zélé Antoine Nicot Philippe Perret Sylvain Gandon Ana Rivero 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2015,370(1675)
Avian malaria has historically played an important role as a model in the study of human malaria, being a stimulus for the development of medical parasitology. Avian malaria has recently come back to the research scene as a unique animal model to understand the ecology and evolution of the disease, both in the field and in the laboratory. Avian malaria is highly prevalent in birds and mosquitoes around the world and is amenable to laboratory experimentation at each stage of the parasite''s life cycle. Here, we take stock of 5 years of experimental laboratory research carried out using Plasmodium relictum SGS1, the most prevalent avian malaria lineage in Europe, and its natural vector, the mosquito Culex pipiens. For this purpose, we compile and analyse data obtained in our laboratory in 14 different experiments. We provide statistical relationships between different infection-related parameters, including parasitaemia, gametocytaemia, host morbidity (anaemia) and transmission rates to mosquitoes. This analysis provides a wide-ranging picture of the within-host and between-host parameters that may bear on malaria transmission and epidemiology. 相似文献