全文获取类型
收费全文 | 536篇 |
免费 | 30篇 |
专业分类
566篇 |
出版年
2023年 | 4篇 |
2022年 | 1篇 |
2021年 | 6篇 |
2020年 | 1篇 |
2019年 | 4篇 |
2018年 | 14篇 |
2017年 | 15篇 |
2016年 | 12篇 |
2015年 | 22篇 |
2014年 | 33篇 |
2013年 | 60篇 |
2012年 | 41篇 |
2011年 | 81篇 |
2010年 | 59篇 |
2009年 | 40篇 |
2008年 | 15篇 |
2007年 | 17篇 |
2006年 | 13篇 |
2005年 | 11篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 11篇 |
2001年 | 12篇 |
2000年 | 16篇 |
1999年 | 7篇 |
1998年 | 8篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有566条查询结果,搜索用时 15 毫秒
61.
Growth Rate of the Microalga Tetraselmis suecica Changes the Biochemical Composition of Artemia Species 总被引:1,自引:0,他引:1
The impact of different microalgal semicontinuous cultures on growth and biochemical composition in the next link of the
food chain was tested using the filter feeder Artemia species as a model. The marine microalga Tetraselmis suecica was cultured semicontinuously with renewal rates between 10% and 50% and used to feed Artemia. Microalgal cultures maintained with a low renewal rate that had biochemical composition similar to that of the stationary-phase
cultures commonly used in aquaculture produced poor growth and survival and low food-conversion efficiency compared to cultures
maintained with a high renewal rate. Changes in the renewal rate in microalgal cultures also resulted in important changes
in the gross biochemical composition of the filter feeder. The gross biochemical composition of the Artemia resembled that of the microalgae used as food except for total lipid content. The percentage of protein in the organic fraction
of Artemia increased from 45% to 65% of the organic weight with increasing renewal rates in the microalgal cultures, while the carbohydrate
percentage decreased under the same conditions. Higher renewal rates resulted in higher lipid percentages in the microalga,
but in Artemia the percentage of lipids decreased from 19% of the organic weight with a renewal rate of 10%, to 13% with a renewal rate
of 50%. The percentage of all polyunsaturated fatty acids in Artemia, including 20:5n-3, increased slightly with increasing renewal rates in the microalgal cultures. Results emphasize the importance
of controlling microalgal nutritional value for the success of aquaculture food chains in which filter feeders are involved.
Received October 15, 2000; accepted December 29, 2000. 相似文献
62.
J. Fábregas E. D. Morales N. Polanco M. Patiño A. Otero J. F. Tobar 《World journal of microbiology & biotechnology》1996,12(1):47-49
The marine microalga Phaeodactylum tricornutum was cultivated in semi-continuous culture under mixotrophic conditions with the soluble fractions of potato, rye and wheat flours that had been naturally fermented, at 2% or 4% (w/v). The rye flour produced the highest microalgal cellular density of 90×106 cells.ml-1 when supplemented with NaNO3 and NaH2PO4. The autotrophic control only gave 57×106 cells.ml-1. The value of agricultural surpluses, such as rye flour, can therefore be increased by its use in the production of valuable, microalgal biomass which is rich in protein, pigments and fatty acids. 相似文献
63.
Sikorski J Teshima H Nolan M Lucas S Hammon N Deshpande S Cheng JF Pitluck S Liolios K Pagani I Ivanova N Huntemann M Mavromatis K Ovchinikova G Pati A Tapia R Han C Goodwin L Chen A Palaniappan K Land M Hauser L Ngatchou-Djao OD Rohde M Pukall R Spring S Abt B Göker M Detter JC Woyke T Bristow J Markowitz V Hugenholtz P Eisen JA Kyrpides NC Klenk HP Lapidus A 《Standards in genomic sciences》2011,4(3):331-341
Mahella australiensis Bonilla Salinas et al. 2004 is the type species of the genus Mahella, which belongs to the family Thermoanaerobacteraceae. The species is of interest because it differs from other known anaerobic spore-forming bacteria in its G+C content, and in certain phenotypic traits, such as carbon source utilization and relationship to temperature. Moreover, it has been discussed that this species might be an indigenous member of petroleum and oil reservoirs. This is the first completed genome sequence of a member of the genus Mahella and the ninth completed type strain genome sequence from the family Thermoanaerobacteraceae. The 3,135,972 bp long genome with its 2,974 protein-coding and 59 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project. 相似文献
64.
Phillips OL Baker TR Arroyo L Higuchi N Killeen TJ Laurance WF Lewis SL Lloyd J Malhi Y Monteagudo A Neill DA Vargas PN Silva JN Terborgh J Martínez RV Alexiades M Almeida S Brown S Chave J Comiskey JA Czimczik CI Di Fiore A Erwin T Kuebler C Laurance SG Nascimento HE Olivier J Palacios W Patiño S Pitman NC Quesada CA Saldias M Lezama AT Vinceti B 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2004,359(1443):381-407
Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and biodiversity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional-scale patterns of 'tree turnover' (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (ii) turnover rates have increased throughout Amazonia over the past two decades; (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia; (iv) recruitment rates have consistently exceeded mortality rates; (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites; and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation-related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that long-acting and widespread environmental changes are stimulating the growth and productivity of Amazon forests. 相似文献
65.
Lang E Teshima H Lucas S Lapidus A Hammon N Deshpande S Nolan M Cheng JF Pitluck S Liolios K Pagani I Mikhailova N Ivanova N Mavromatis K Pati A Tapia R Han C Goodwin L Chen A Palaniappan K Land M Hauser L Chang YJ Jeffries CD Brambilla EM Kopitz M Rohde M Göker M Tindall BJ Detter JC Woyke T Bristow J Eisen JA Markowitz V Hugenholtz P Klenk HP Kyrpides NC 《Standards in genomic sciences》2011,4(1):81-90
66.
Labutti K Pukall R Steenblock K Glavina Del Rio T Tice H Copeland A Cheng JF Lucas S Chen F Nolan M Bruce D Goodwin L Pitluck S Ivanova N Mavromatis K Ovchinnikova G Pati A Chen A Palaniappan K Land M Hauser L Chang YJ Jeffries CD Chain P Saunders E Brettin T Detter JC Han C Göker M Bristow J Eisen JA Markowitz V Hugenholtz P Kyrpides NC Klenk HP Lapidus A 《Standards in genomic sciences》2009,1(2):159-165
Anaerococcus prevotii (Foubert and Douglas 1948) Ezaki et al. 2001 is the type species of the genus, and is of phylogenetic interest because of its arguable assignment to the provisionally arranged family 'Peptostreptococcaceae'. A. prevotii is an obligate anaerobic coccus, usually arranged in clumps or tetrads. The strain, whose genome is described here, was originally isolated from human plasma; other strains of the species were also isolated from clinical specimen. Here we describe the features of this organism, together with the complete genome sequence and annotation. This is the first completed genome sequence of a member of the genus. Next to Finegoldia magna, A. prevotii is only the second species from the family 'Peptostreptococcaceae' for which a complete genome sequence is described. The 1,998,633 bp long genome (chromosome and one plasmid) with its 1852 protein-coding and 61 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project. 相似文献
67.
68.
Kar S Mandal A Mohapatra PK Samanta S Pati BR Mondal KC 《Journal of industrial microbiology & biotechnology》2008,35(4):245-249
In the present study, the optimum conditions for the production of xylanase by immobilized spores of Trichoderma reesei SAF3 in calcium alginate beads were determined. The operational stability of the beads during xylanase production under semi-continuous
fermentation was also studied. The influence of alginate concentration (1, 2, 3, and 4%) and initial cell loading (100, 200,
300, 400, and 500 beads per flask) on xylanase production was considered. The production of xylanase was found to increase
significantly with increasing concentration of alginate and reached a maximum yield of 3.12 ± 0.18 U ml−1 at 2% (w/v). The immobilized cells produced xylanase consistently up to 10 cycles and reached a maximum level at the forth
cycle (3.36 ± 0.2 U ml−1). 相似文献
69.
Sean D. Hooper Iain J. Anderson Amrita Pati Daniel Dalevi Konstantinos Mavromatis Nikos C. Kyrpides 《Nucleic acids research》2009,37(7):2096-2104
In order to simplify and meaningfully categorize large sets of protein sequence data, it is commonplace to cluster proteins based on the similarity of those sequences. However, it quickly becomes clear that the sequence flexibility allowed a given protein varies significantly among different protein families. The degree to which sequences are conserved not only differs for each protein family, but also is affected by the phylogenetic divergence of the source organisms. Clustering techniques that use similarity thresholds for protein families do not always allow for these variations and thus cannot be confidently used for applications such as automated annotation and phylogenetic profiling. In this work, we applied a spectral bipartitioning technique to all proteins from 53 archaeal genomes. Comparisons between different taxonomic levels allowed us to study the effects of phylogenetic distances on cluster structure. Likewise, by associating functional annotations and phenotypic metadata with each protein, we could compare our protein similarity clusters with both protein function and associated phenotype. Our clusters can be analyzed graphically and interactively online. 相似文献
70.
Samiran Sona Gauri Santi M. Mandal Keshab C. Mondal Satyahari Dey Bikas R. Pati 《Bioresource technology》2009,100(18):4240-4243
A strain was selected by its highest extracellular polysaccharide (EPS) production ability compare to other isolates from the same rhizospheric soil. The selected strain was identified by 16S rDNA sequencing and designated as SSB81. Phylogenetic analysis of the gene sequence showed its close relatedness with Azotobacter vinelandii and Azotobacter salinestris. Maximum EPS (2.52 g l−1) was recovered when the basal medium was supplemented with glucose (2.0%), riboflavin (1 mg l−1) and casamino acid (0.2%). The EPS showed a stable viscosity level at acidic pH (3.0–6.5) and the pyrolysis temperature was found to be at 116.73 °C with an enthalpy (ΔH) of 1330.72 Jg−1. MALDI TOF mass spectrometric result suggests that polymer contained Hex5Pent3 as oligomeric building subunit. SEM studies revealed that the polymer had a porous structure with small pore size distribution indicating the compactness of the polymer. This novel EPS may find possible application as a polymer for environmental bioremediation and biotechnological processes. 相似文献