全文获取类型
收费全文 | 586篇 |
免费 | 41篇 |
专业分类
627篇 |
出版年
2023年 | 4篇 |
2022年 | 12篇 |
2021年 | 24篇 |
2020年 | 17篇 |
2019年 | 20篇 |
2018年 | 17篇 |
2017年 | 12篇 |
2016年 | 20篇 |
2015年 | 37篇 |
2014年 | 42篇 |
2013年 | 47篇 |
2012年 | 52篇 |
2011年 | 48篇 |
2010年 | 30篇 |
2009年 | 33篇 |
2008年 | 30篇 |
2007年 | 34篇 |
2006年 | 35篇 |
2005年 | 27篇 |
2004年 | 21篇 |
2003年 | 18篇 |
2002年 | 15篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有627条查询结果,搜索用时 0 毫秒
131.
Sofie M. G. Saerens Freddy R. Delvaux Kevin J. Verstrepen Johan M. Thevelein 《Microbial biotechnology》2010,3(2):165-177
The need to understand and control ester synthesis is driven by the fact that esters play a key role in the sensorial quality of fermented alcoholic beverages like beer, wine and sake. As esters are synthesized in yeast via several complex metabolic pathways, there is a need to gain a clear understanding of ester metabolism and its regulation. The individual genes involved, their functions and regulatory mechanisms have to be identified. In alcoholic beverages, there are two important groups of esters: the acetate esters and the medium-chain fatty acid (MCFA) ethyl esters. For acetate ester synthesis, the genes involved have already been cloned and characterized. Also the biochemical pathways and the regulation of acetate ester synthesis are well defined. With respect to the molecular basis of MCFA ethyl ester synthesis, however, significant progress has only recently been made. Next to the characterization of the biochemical pathways and regulation of ester synthesis, a new and more important question arises: what is the advantage for yeast to produce these esters? Several hypotheses have been proposed in the past, but none was satisfactorily. This paper reviews the current hypotheses of ester synthesis in yeast in relation to the complex regulation of the alcohol acetyl transferases and the different factors that allow ester formation to be controlled during fermentation. 相似文献
132.
Potential of selected lactic acid bacteria to produce food compatible antifungal metabolites 总被引:1,自引:0,他引:1
De Muynck C Leroy AI De Maeseneire S Arnaut F Soetaert W Vandamme EJ 《Microbiological research》2004,159(4):339-346
The aim of this study was to assess the potential of lactic acid bacteria to inhibit the outgrowth of some common food-spoiling fungi. Culture supernatants of 17 lactic acid bacterial strains as well as of three commercial probiotic cultures were evaluated for antifungal activity using an agar-diffusion method. The method parameters were chosen in order to reveal compounds for potential use in food (bio)preservation. Thirteen strains showed antifungal activity of which five strains were very promising: Lactobacillus acidophilus LMG 9433, L. amylovorus DSM 20532, L. brevis LMG 6906, L. coryniformis subsp. coryniformis LMG 9196 and L. plantarum LMG 6907. Four of these five strains were further examined; it was found that the produced antifungal metabolites were pH-dependent. The exact chemical nature of these substances has not been revealed yet. 相似文献
133.
134.
Barbé S Van Mellaert L Theys J Geukens N Lammertyn E Lambin P Anné J 《FEMS microbiology letters》2005,251(1):67-73
A bacterium, isolated from contaminated soils around a chemical factory and named strain DSP3 was capable of biodegrading both chlorpyrifos and 3,5,6-trichloro-2-pyridinol. Based on the results of phenotypic features, phylogenetic similarity of 16S rRNA gene sequences, DNA G+C content, and DNA homology between strain DSP3 and reference strains, strain DSP3 was identified as Alcaligenes faecalis. Chlorpyrifos was utilized as the sole source of carbon and phosphorus by strain DSP3. We examined the role of strain DSP3 in the degradation of chlorpyrifos and 3,5,6-trichloro-2-pyridinol under different culture conditions. Parathion and diazinon could also be degraded by strain DSP3 when provided as the sole sources of carbon and phosphorus. An addition of strain DSP3 (10(8)cells g(-1)) to soil with chlorpyrifos (100 mg kg(-1)) resulted in a higher degradation rate than the one obtained from non-inoculated soils. Different degradation rates of chlorpyrifos in six types of treated soils suggested that soils used for cabbage growing in combination with inoculation of strain DSP3 showed enhanced microbial degradation of chlorpyrifos. 相似文献
135.
Lise Goltermann Marie Sofie Yoo Larsen Rajat Banerjee Andreas C. Joerger Michael Ibba Thomas Bentin 《PloS one》2010,5(4)
Background
Global residue-specific amino acid mutagenesis can provide important biological insight and generate proteins with altered properties, but at the risk of protein misfolding. Further, targeted libraries are usually restricted to a handful of amino acids because there is an exponential correlation between the number of residues randomized and the size of the resulting ensemble. Using GFP as the model protein, we present a strategy, termed protein evolution via amino acid and codon elimination, through which simplified, native-like polypeptides encoded by a reduced genetic code were obtained via screening of reduced-size ensembles.Methodology/Principal Findings
The strategy involves combining a sequential mutagenesis scheme to reduce library size with structurally stabilizing mutations, chaperone complementation, and reduced temperature of gene expression. In six steps, we eliminated a common buried residue, Phe, from the green fluorescent protein (GFP), while retaining activity. A GFP variant containing 11 Phe residues was used as starting scaffold to generate 10 separate variants in which each Phe was replaced individually (in one construct two adjacent Phe residues were changed simultaneously), while retaining varying levels of activity. Combination of these substitutions to generate a Phe-free variant of GFP abolished fluorescence. Combinatorial re-introduction of five Phe residues, based on the activities of the respective single amino acid replacements, was sufficient to restore GFP activity. Successive rounds of mutagenesis generated active GFP variants containing, three, two, and zero Phe residues. These GFPs all displayed progenitor-like fluorescence spectra, temperature-sensitive folding, a reduced structural stability and, for the least stable variants, a reduced steady state abundance.Conclusions/Significance
The results provide strategies for the design of novel GFP reporters. The described approach offers a means to enable engineering of active proteins that lack certain amino acids, a key step towards expanding the functional repertoire of uniquely labeled proteins in synthetic biology. 相似文献136.
Sofie Marijke Braet Anouk van Hooij Epco Hasker Erik Fransen Abdou Wirdane Abdallah Baco Saverio Grillone Nimer Ortuno-Gutierrez Younoussa Assoumani Aboubacar Mzembaba Paul Corstjens Leen Rigouts Annemieke Geluk Bouke Catherine de Jong 《PLoS neglected tropical diseases》2021,15(11)
The World Health Organization (WHO) endorsed diagnosis of leprosy (also known as Hansen’s disease) entirely based on clinical cardinal signs, without microbiological confirmation, which may lead to late or misdiagnosis. The use of slit skin smears is variable, but lacks sensitivity. In 2017–2018 during the ComLep study, on the island of Anjouan (Union of the Comoros; High priority country according to WHO, 310 patients were diagnosed with leprosy (paucibacillary = 159; multibacillary = 151), of whom 263 were sampled for a skin biopsy and fingerstick blood, and 260 for a minimally-invasive nasal swab. In 74.5% of all skin biopsies and in 15.4% of all nasal swabs, M. leprae DNA was detected. In 63.1% of fingerstick blood samples, M. leprae specific antibodies were detected with the quantitative αPGL-I test. Results show a strong correlation of αPGL-I IgM levels in fingerstick blood and RLEP-qPCR positivity of nasal swabs, with the M. leprae bacterial load measured by RLEP-qPCR of skin biopsies. Patients with a high bacterial load (≥50,000 bacilli in a skin biopsy) can be identified with combination of counting lesions and the αPGL-I test. To our knowledge, this is the first study that compared αPGL-I IgM levels in fingerstick blood with the bacterial load determined by RLEP-qPCR in skin biopsies of leprosy patients. The demonstrated potential of minimally invasive sampling such as fingerstick blood samples to identify high bacterial load persons likely to be accountable for the ongoing transmission, merits further evaluation in follow-up studies. 相似文献
137.
Sofie Martens Nozomi Takahashi Gillian Blancke Niels Vandamme Hanne Verschuere Tatyana Divert Marnik Vuylsteke Geert Berx Peter Vandenabeele 《Cell death & disease》2022,13(4)
Cancers acquire several capabilities to survive the multistep process in carcinogenesis. Resisting cell death is one of them. Silencing of the necroptosis initiator Ripk3 occurs in a wide variety of cancer types including melanoma. Little is known about the role of the necroptosis executioner MLKL in tumor development. Studies often indicate opposing roles for MLKL as a tumor-suppressing or a tumor-promoting protein. This study investigates the role of MLKL during melanoma initiation and progression using a tamoxifen-inducible melanoma mouse model driven by melanocyte-specific overexpression of mutated Braf and simultaneous deletion of Pten (BrafV600EPten−/−). In this model we observed a clear sex difference: melanoma initiation and progression were faster in females mice. Mlkl deficiency in male mice resulted in a modest but significant reduction of nevi growth rate compared to the littermate control. In these mice, infiltration and expansion of melanoma cells in the inguinal lymph node were also modestly decreased. This is likely to be a consequence of the delay in nevi development. No significant difference was observed in the Mlkl-deficient condition in female mice in which melanoma development was faster. Overall, our results indicate that in this genetic model MLKL has a minor role during melanoma initiation and progression.Subject terms: Experimental models of disease, Cancer models, Melanoma, Necroptosis 相似文献
138.
Emma L. Wright Colin R. Black Benjamin L. Turner Sofie Sjögersten 《Global Change Biology》2013,19(12):3775-3789
Tropical peatlands play an important role in the global storage and cycling of carbon (C) but information on carbon dioxide (CO2) and methane (CH4) fluxes from these systems is sparse, particularly in the Neotropics. We quantified short and long‐term temporal and small scale spatial variation in CO2 and CH4 fluxes from three contrasting vegetation communities in a domed ombrotrophic peatland in Panama. There was significant variation in CO2 fluxes among vegetation communities in the order Campnosperma panamensis > Raphia taedigera > Cyperus. There was no consistent variation among sites and no discernible seasonal pattern of CH4 flux despite the considerable range of values recorded (e.g. ?1.0 to 12.6 mg m?2 h?1 in 2007). CO2 fluxes varied seasonally in 2007, being greatest in drier periods (300–400 mg m?2 h?1) and lowest during the wet period (60–132 mg m?2 h?1) while very high emissions were found during the 2009 wet period, suggesting that peak CO2 fluxes may occur following both low and high rainfall. In contrast, only weak relationships between CH4 flux and rainfall (positive at the C. panamensis site) and solar radiation (negative at the C. panamensis and Cyperus sites) was found. CO2 fluxes showed a diurnal pattern across sites and at the Cyperus sp. site CO2 and CH4 fluxes were positively correlated. The amount of dissolved carbon and nutrients were strong predictors of small scale within‐site variability in gas release but the effect was site‐specific. We conclude that (i) temporal variability in CO2 was greater than variation among vegetation communities; (ii) rainfall may be a good predictor of CO2 emissions from tropical peatlands but temporal variation in CH4 does not follow seasonal rainfall patterns; and (iii) diurnal variation in CO2 fluxes across different vegetation communities can be described by a Fourier model. 相似文献
139.
140.
Ramet demography in a ring-forming clonal sedge 总被引:5,自引:0,他引:5