全文获取类型
收费全文 | 174篇 |
免费 | 7篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 7篇 |
2012年 | 13篇 |
2011年 | 7篇 |
2010年 | 9篇 |
2009年 | 9篇 |
2008年 | 8篇 |
2007年 | 19篇 |
2006年 | 10篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 1篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有181条查询结果,搜索用时 218 毫秒
41.
Kristine Lysnes Gunhild Bødtker Terje Torsvik Eva Ø. Bjørnestad Egil Sunde 《Applied microbiology and biotechnology》2009,83(6):1143-1157
The microbial response to produced water reinjection (PWRI) in a North Sea oil field was investigated by a combination of
cultivation and culture-independent molecular phylogenetic techniques. Special emphasise was put on the relationship between
sulphate-reducing bacteria (SRB) and nitrate-reducing bacteria (NRB), and results were used to evaluate the possibility of
nitrate treatment as a souring management tool during PWRI. Samples were collected by reversing the flow of the injection
water, which provided samples from around the injection area. The backflowed samples were compared to produced water from
the same platform and to backflowed samples from a biocide-treated seawater injector, which was the previous injection water
treatment of the PWRI well. Results showed that reinjection of produced water promoted growth of thermophilic SRB. Thermophilic
fatty acid oxidising NRB and potential nitrate-reducing sulphide-oxidising bacteria were also found. The finding of thermophilic
NRB makes nitrate treatment during PWRI possible, although higher nitrate concentration will be necessary to compensate for
the increased SRB activity. 相似文献
42.
Gunhild Bødtker Kristine Lysnes Terje Torsvik Eva Ø. Bjørnestad Egil Sunde 《Journal of industrial microbiology & biotechnology》2009,36(3):439-450
Reservoir souring in offshore oil fields is caused by hydrogen sulphide (H2S) produced by sulphate-reducing bacteria (SRB), most often as a consequence of sea water injection. Biocide treatment is
commonly used to inhibit SRB, but has now been replaced by nitrate treatment on several North Sea oil fields. At the Statfjord
field, injection wells from one nitrate-treated reservoir and one biocide-treated reservoir were reversed (backflowed) and
sampled for microbial analysis. The two reservoirs have similar properties and share the same pre-nitrate treatment history.
A 16S rRNA gene-based community analysis (PCR-DGGE) combined with enrichment culture studies showed that, after 6 months of
nitrate injection (0.25 mM NO3
−), heterotrophic and chemolithotrophic nitrate-reducing bacteria (NRB) formed major populations in the nitrate-treated reservoir.
The NRB community was able to utilize the same substrates as the SRB community. Compared to the biocide-treated reservoir,
the microbial community in the nitrate-treated reservoir was more phylogenetically diverse and able to grow on a wider range
of substrates. Enrichment culture studies showed that SRB were present in both reservoirs, but the nitrate-treated reservoir
had the least diverse SRB community. Isolation and characterisation of one of the dominant populations observed during nitrate
treatment (strain STF-07) showed that heterotrophic denitrifying bacteria affiliated to Terasakiella probably contributed significantly to the inhibition of SRB.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
43.
44.
Effects of water regime on archaeal communities in Arctic soils from Spitsbergen were studied using denaturing gradient gel electrophoresis (DGGE) of amplified 16S rRNA genes, with subsequent sequencing of amplicons and ordination analysis of binary DGGE data. Samples with major differences in soil water regime showed significant differences in their archaeal community profiles. Methanomicrobiales, Methanobacteriaceae and Methanosaeta were detectable only in environments that were wet during most of the growth season, while a novel euryarchaeotal cluster was detected only in less reduced solifluction material. Group 1.3b of Crenarchaeota had a high relative abundance within the archaeal community in a wide range of wet soils. Along a natural soil moisture gradient, changes in archaeal community composition were observed only in upper soil layers. The results indicated that members of Methanomicrobiales were relatively tolerant to soil aeration. Differences in archaeal community composition associated with soil water regime were predominant over regional and seasonal variation, and over differences between individual wetlands. The results suggest that the observed 'on-off switch' mechanism of soil hydrology for large-scale variations in methane emissions from northern wetlands is at least partly caused by differences in the community structure of organisms involved in methane production. 相似文献
45.
Per Strset Oddvar Stokke Egil Jellum 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1978,145(3):351-357
Gas chromatography—mass spectrometry with an on-line data system was used to identify monosaccharides and monosaccharide derivatives in human seminal plasma. The carbohydrates were converted into the methoxime—trimethylsilyl derivatives before separation in open tubular glass capillary columns coated with SE-30. Twenty-one different compounds were detected in the seminal fluid, of which twelve have not been recognized before. Seventeen of the monosaccharides have previously been identified in urine. Similar patterns of sugars were found both in fertile and infertile individuals, including one with azoospermia. The compounds identified are, with the possible exception of
-ribose, present as free monosaccharides at the time of ejaculation, and they do not seem to be preformed by spermatozoa. 相似文献
46.
Henneke P Takeuchi O Malley R Lien E Ingalls RR Freeman MW Mayadas T Nizet V Akira S Kasper DL Golenbock DT 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(7):3970-3977
Group B streptococci (GBS) vigorously activate inflammatory responses. We reported previously that a secreted GBS "factor" activates phagocytes via Toll-like receptor (TLR)2 and TLR6, but that GBS cell walls activate cells independently of these receptors. We hypothesized that the phagocytic immune functions in response to GBS, such as inflammation, uptake, and elimination of bacteria, occur through a coordinated engagement of TLRs, along with the coreceptors CD14 and CD11b/CD18. Using various knockout mice we show that GBS-induced activation of p38 and NF-kappaB depends upon the expression of the cytoplasmic TLR adapter protein, myeloid differentiation factor 88 (MyD88), but not TLR2 and/or TLR4. Macrophages with deletions of CD14 and complement receptor 3 had a normal cytokine response to whole bacteria, although the response to GBS factor was abrogated in CD14-null cells. The intracellular formation of bactericidal oxygen species proved to be MyD88 dependent; however, uptake of GBS, a prerequisite for intracellular killing by O(2) radicals, occurred independently of MyD88. While deletion of complement receptor 3 greatly diminished the uptake of opsonized GBS, it did not affect the formation of bactericidal O(2) radicals or inflammatory signaling intermediates. We conclude that the inflammatory, bactericidal, and phagocytic responses to GBS occur via parallel but independent processes. 相似文献
47.
Sakshaug E.; Bricaud A.; Dandonneau Y.; Falkowski P.G.; Kiefer D.A.; Legendre L.; Morel A.; Parslow J.; Takahashi M. 《Journal of plankton research》1998,20(3):603
Regrettably, parentheses are missing in Equation 16 on p. 1649.Equation 16 should read:
相似文献
48.
Anne M. Myhre Egil Hagen Rune Blomhoff Kaare R. Norum 《The Journal of nutritional biochemistry》1998,9(12):705-711
Following uptake of chylomicron remnant retinyl esters by the macrophage cell line J774, the retinyl esters are hydrolyzed to retinol before retinol is further metabolized to retinal and the various retinoic acid isoforms. One hour after the addition of chylomicron remnant [3H]retinyl esters to the cells, the percentage of cell-associated radioactivity in the retinyl ester fraction had decreased from approximately 90% to approximately 40%, whereas the radioactivity in the retinol fraction increased correspondingly. After 4 hours of incubation, more than 79% of the radioactive retinyl esters had been hydrolyzed to retinol. When we measured incorporation of radioactivity in the protein fraction, we observed that the level of [3H]retinoylated proteins increased rapidly the first 4 hours, and then continued to increase at a lower rate up to 24 hours, when approximately 0.6% of the cell-associated radioactivity was covalently bound to protein. These data suggest that approximately 0.18% of all the cellular proteins might be retinoylated under such conditions. In summary, in the present study we have demonstrated that retinoids taken up by a macrophage cell line as chylomicron remnant retinyl esters, a physiologic plasma transport molecule for vitamin A, might be covalently linked to proteins. Such retinoylation might be relevant both for normal function, as well as for the toxic and teratogenic effects of vitamin A. 相似文献
49.
Photoadaptive responses in the toxic and bloom-forming dinoflagellates Gyrodinium aureolum Hulbert, Gymnodinium galatheanum Braarud, and two strains of Prorocentrum minimum (Pavillard)Schiller were evaluated with respect to pigment composition, light-harvesting characteristics, carbon and nitrogen contents, and growth rates in shade- and light-adapted cells. The two former species were grown at scalar irradiances of 30 and 170 μmol · m ?2 at a 12-h daylength at 20° C. The two strains of P. minimum were grown at 35 and 500 μmol. m?2· s?1 at a 2-h daylength at 20° C. For the first time, chlorophyll (chl) c3, characteristic of several bloom-forming prymnesiophytes, was detected in G. aureolum and G. galatheanum. Photoadaptional status affected the pigment composition strongly, and the interpretation of the variation depended on whether the pigment composition was normalized per cell, carbon, or chl a. Species-specific and photoadaptional differences in chl a-specific absorption (°ac, 400–700 nm) and chl a-normalized fluorescence excitation spectra of photosystem II fluorescence with or without addition of DCMU (°F and °FDCMU 400–700 nm) were evident. Gyrodinium aureolum and G. galatheanum exhibited in vivo spectral characteristics similar to chl c3-containing prymnesiophytes in accordance with their similar pigmentation. Prorocentrum minimum had in vivo absorption and fluorescence characteristics typical for peridinin-containing dinoflagellates. Species-specific differences in in vivo absorption were also observed as a function of package effect vs. growth irradiance. This effect could be explained by differences in intracellular pigment content, cell size/shape, and chloroplast morphology/numbers. Light- and shade-adapted cells of P. minimum contained 43 and 17% of photoprotective carotenoids (diadino + diatoxanthin) relative to chl a, respectively. The photoprotective function of these carotenoids was clearly observed as a reduction in °F and °F DCMU at 400–540 nm compared to °ac in light-adapted cells of P. minimum. Spectrally weighted light absorption (normalized to chl a and carbon, 400–700 nm) varied with species and growth conditions. The use of quantum-corrected and normalized fluorescence excitation spectra with or without DCMU-treated cells to estimate photosynthetically usable light is discussed. The usefulness of in vitro absorption and fluorescence excitation spectra for estimation of the degradation status of chl a and the ratio of chl a to total pigments is also discussed. 相似文献
50.
Peter Egil Nielsen 《Origins of life and evolution of the biosphere》1993,23(5-6):323-327
It is proposed that the primordial genetic material could have been peptide nucleic aicds,i.e., DNA analogues having a peptide backbone. PNA momomers based on the amino acid, , -diaminobutyric acid or ornithine are suggested as compounds that could have been formed in the prebiotic soup. Finally, the possibility of a PNA/RNA world is presented, in which PNA constitutes the stable genetic material, while RNA which may be polymerized using the PNA as template accounts for enzymatic activities including PNA replication. 相似文献