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151.
Dissecting a biodiversity hotspot: The importance of environmentally marginal habitats in the Atlantic Forest Domain of South America
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The RNAse III Drosha is responsible for the first step of microRNA maturation, the cleavage of primary miRNA to produce the precursor miRNA. Processing by Drosha is finely regulated and influences the amount of mature microRNA in a cell. We describe in the present work a method to quantify Drosha processing activity in-vivo, which is applicable to any microRNA. With respect to other methods for measuring Drosha activity, our system is faster and scalable, can be used with any cellular system and does not require cell sorting or use of radioactive isotopes.This system is useful to study regulation of Drosha activity in physiological and pathological conditions. 相似文献
156.
Markus Buchetics Martin Dragosits Michael Maurer Corinna Rebnegger Danilo Porro Michael Sauer Brigitte Gasser Diethard Mattanovich 《Biotechnology and bioengineering》2011,108(10):2403-2412
The demand for recombinant proteins both for biopharmaceutical and technical applications is rapidly growing, and therefore the need to establish highly productive expression systems is steadily increasing. Yeasts, such as Pichia pastoris, are among the widely used production platforms with a strong emphasis on secreted proteins. Protein secretion is a limiting factor of productivity. There is strong evidence that secretion is coupled to specific growth rate (µ) in yeast, being higher at higher µ. For maximum productivity and product titer, high specific secretion rates at low µ would be desired. At high secretion rates cultures contain a large fraction of cells in the G2 and M phases of cell cycle. Consequently, the cell design target of a high fraction of cells in G2 + M phase was achieved by constitutive overexpression of the cyclin gene CLB2. Together with predictive process modeling this reverse engineered production strain improved the space time yield (STY) of an antibody Fab fragment by 18% and the product titer by 53%. This concept was verified with another secreted protein, human trypsinogen. Biotechnol. Bioeng. 2011;108: 2403–2412. © 2011 Wiley Periodicals, Inc. 相似文献
157.
Spoilage-related activity of Carnobacterium maltaromaticum strains in air-stored and vacuum-packed meat 总被引:2,自引:0,他引:2
Casaburi A Nasi A Ferrocino I Di Monaco R Mauriello G Villani F Ercolini D 《Applied and environmental microbiology》2011,77(20):7382-7393
One hundred three isolates of Carnobacterium spp. from raw meat were analyzed by random amplification of polymorphic DNA (RAPD) and PCR and were identified by 16S rRNA gene sequencing. Forty-five strains of Carnobacterium maltaromaticum were characterized for their growth capabilities at different temperatures, NaCl concentrations, and pH values and for in vitro lipolytic and proteolytic activities. Moreover, their spoilage potential in meat was investigated by analyzing the release of volatile organic compounds (VOCs) in meat stored in air or vacuum packs. Almost all the strains were able to grow at 4, 10, and 20°C, at pH values of 6 to 9, and in the presence of 2.5% NaCl. The release of VOCs by each strain in beef stored at 4°C in air and vacuum packs was evaluated by headspace solid-phase microextraction (HS-SPME)-gas chromatography-mass spectrometry (GC-MS) analysis. All the meat samples inoculated and stored in air showed higher numbers of VOCs than the vacuum-packed meat samples. Acetoin, 1-octen-3-ol, and butanoic acid were the compounds most frequently found under both storage conditions. The contaminated meat samples were evaluated by a sensory panel; the results indicated that for all sensory odors, no effect of strain was significant (P > 0.05). The storage conditions significantly affected (P < 0.05) the perception of dairy, spoiled-meat, and mozzarella cheese odors, which were more intense in meat stored in air than in vacuum packs but were never very intense. In conclusion, different strains of C. maltaromaticum can grow efficiently in meat stored at low temperatures both in air and in vacuum packs, producing volatile molecules with low sensory impacts, with a negligible contribution to meat spoilage overall. 相似文献
158.
Cooling of pacu (Piaractus mesopotamicus) embryos at various stages of development for 6 or 10 hours
The objective of this research was to verify the effects of cooling embryos of pacu, Piaractus mesopotamicus, in four stages of development during two stocking periods. The stages of embryo development were at: blastoderm, ∼64 cells—1.4 h after fertilization (haf); 25% of the epiboly movement—5.2 haf; blastoporous closing—8.0 haf; and optical vesicle appearing—13.3 haf. Embryos were exposed to a cryoprotectant solution containing methanol (10%) and sucrose (0.5 M). Thereafter, embryos were submitted to a cooling curve until they reached −8 °C, and then kept cooled for 6 or 10 h. In addition, for each stage of embryonic development, a control group with uncooled embryos was used to compare hatching rates. The total number of larvae from the first two stages of ontogenetic development (1.4 and 5.2 haf) was lower compared to the other stages (0.0 and 8.0 haf). There was no significant difference between stages 8.0 and 13.3 haf for the total number of larvae (49.9 ± 6.7% and 55.2 ± 6.7%, respectively). Embryo diameter varied according to embryonic stage, providing evidence of differences in membrane permeability. There was a negative correlation between embryo diameter and the total number of larvae (r = −0.372). In conclusion, use of embryonic stages 8.0 and 13.3 haf were recommended for maintaining cooled pacu embryos at −8 °C for 6 or 10 h. 相似文献
159.
Porro D Gasser B Fossati T Maurer M Branduardi P Sauer M Mattanovich D 《Applied microbiology and biotechnology》2011,89(4):939-948
Recombinant DNA (rDNA) technologies allow the production of a wide range of peptides, proteins and metabolites from naturally
non-producing cells. Since human insulin was the first heterologous compound produced in a laboratory in 1977, rDNA technology
has become one of the most important technologies developed in the 20th century. Recombinant protein and metabolites production
is a multi-billion dollar market. The development of a new product begins with the choice of the cell factory. The final application
of the compound dictates the main criteria that should be taken into consideration: (1) quality, (2) quantity, (3) yield and
(4) space time yield of the desired product. Quantity and quality are the most predominant requirements that must be considered
for the commercial production of a protein. Quantity and yield are the requirements for the production of a metabolite. Finally,
space time yield is crucial for any production process. It therefore becomes clear why the perfect host does not exist yet,
and why—despite important advances in rDNA applications in higher eukaryotic cells—microbial biodiversity continues to represent
a potential source of attractive cell factories. In this review, we compare the advantages and limitations of the principal
yeast and bacterial workhorse systems. 相似文献
160.