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排序方式: 共有248条查询结果,搜索用时 15 毫秒
91.
Torvinen E Suomalainen S Lehtola MJ Miettinen IT Zacheus O Paulin L Katila ML Martikainen PJ 《Applied and environmental microbiology》2004,70(4):1973-1981
Drinking water distribution systems were analyzed for viable counts of mycobacteria by sampling water from waterworks and in different parts of the systems. In addition, loose deposits collected during mechanical cleaning of the main pipelines were similarly analyzed. The study covered 16 systems at eight localities in Finland. In an experimental study, mycobacterial colonization of biofilms on polyvinyl chloride tubes in a system was studied. The isolation frequency of mycobacteria increased from 35% at the waterworks to 80% in the system, and the number of mycobacteria in the positive samples increased from 15 to 140 CFU/liter, respectively. Mycobacteria were isolated from all 11 deposits with an accumulation time of tens of years and from all 4 deposits which had accumulated during a 1-year follow-up time. The numbers of mycobacteria were high in both old and young deposits (medians, 1.8 x 10(5) and 3.9 x 10(5) CFU/g [dry weight], respectively). Both water and deposit samples yielded the highest numbers of mycobacteria in the systems using surface water and applying ozonation as an intermediate treatment or posttreatment. The number and growth of mycobacteria in system waters correlated strongly with the concentration of assimilable organic carbon in the water leaving the waterworks. The densities of mycobacteria in the developing biofilms were highest at the distal sites of the systems. Over 90% of the mycobacteria isolated from water and deposits belonged to Mycobacterium lentiflavum, M. tusciae, M. gordonae, and a previously unclassified group of mycobacteria. Our results indicate that drinking water systems may be a source for recently discovered new mycobacterial species. 相似文献
92.
T. Lauteala Nina Horelli-Kuitunen Ellen Closs Marja-Liisa Savontaus Mari Lukkarinen Olli Simell James Cunningham Aarno Palotie Pertti Aula 《Human genetics》1997,100(1):80-83
Lysinuric protein intolerance (LPI) is a recessively inherited amino acid disorder characterized by defective efflux of cationic
amino acids at the basolateral membrane of the intestinal and renal tubular epithelium. Recently, cDNAs encoding the related
proteins hCAT-2A and hCAT-2B have been cloned. These two carrier proteins are most likely the product of the same gene, hCAT-2.
Using the hCAT-2B cDNA, we assigned the hCAT-2 gene to chromosome 8p22. Furthermore, by linkage analysis in Finnish LPI families,
we ruled out that hCAT-2B is involved in LPI disease.
Received: 28 October 1996 / Accepted: 20 January 1997 相似文献
93.
Reconstruction of the carbon balance for microsites in a boreal oligotrophic pine fen, Finland 总被引:11,自引:0,他引:11
J. Alm Alexander Talanov Sanna Saarnio Jouko Silvola Elena Ikkonen Heikki Aaltonen Hannu Nykänen Pertti J. Martikainen 《Oecologia》1997,110(3):423-431
Carbon dioxide (CO2) exchange was studied at flark (minerotrophic hollow), lawn and hummock microsites in an oligotrophic boreal pine fen. Statistical
response functions were constructed for the microsites in order to reconstruct the annual CO2 exchange balance from climate data. Carbon accumulation was estimated from the annual net CO2 exchange, methane (CH4) emissions and leaching of carbon. Due to high water tables in the year 1993, the average carbon accumulation at the flark,
Eriophorum lawn, Carex lawn and hummock microsites was high, 2.91, 6.08, 2.83 and 2.66 mol C m–2, respectively, and for the whole peatland it was 5.66 mol m–2 year–1. During the maximum primary production period in midsummer, hummocks with low water tables emitted less methane than predicted
from the average net ecosystem exchange (NEE), while the Carex lawns emitted slightly more. CH4 release during that period corresponded to 16% of the contemporary NEE. Annual C accumulation rate did not correlate with
annual CH4 release in the microsites studied, but the total community CO2 release seemed to be related to CH4 emissions in the wet microsites, again excluding the hummocks. The dependence of CO2 exchange dynamics on weather events suggests that daily balances in C accumulation are labile and can change from net carbon
uptake to net release, primarily in high hummocks on fens under warmer, drier climatic conditions.
Received: 16 August 1996 / Accepted: 30 November 1996 相似文献
94.
Mycobacteria in boreal coniferous forest soils 总被引:3,自引:0,他引:3
95.
Short-term recovery of benthos following disturbance from stream habitat rehabilitation 总被引:4,自引:2,他引:2
Pertti Tikkanen Pekka Laasonen Timo Muotka Arto Huhta Kalevi Kuusela 《Hydrobiologia》1994,273(2):121-130
The recovery of benthic macroinvertebrates after disturbance from stream rehabilitation was studied in the River Livojoki, northern Finland. The stream that had been channelized for log transport was rehabilitated on 1 July 1992 by digging holes and inserting boulders. We measured habitat characteristics and sampled benthic animals before and after rehabilitation, including an unrehabilitated control site. The immediate effect of rehabilitation was a slight decrease in the abundances of benthic insects. Recolonization occurred rapidly, within 10 days. Disturbance of the rehabilitation did not have a detectable effect on the macroinvertebrate community. Most species-level changes and community patterns reflected seasonal life history events. Timing of such rehabilitation work can be critical for the recovery rate, which depends on the colonization abilities of the species present after disturbance. We suggest that many disturbances (including minor floods and moderate rehabilitation procedures) may have only small, short-term effects on benthic communities. We emphasize the importance of considering seasonality in studies of disturbance in streams. 相似文献
96.
97.
Zhen-Ming Ge Seppo Kellomäki Xiao Zhou Heli Peltola Kai-Yun Wang Pertti J. Martikainen 《Bioenergy Research》2012,5(3):637-648
We investigated the seasonal variability of effects of elevated temperature (+3.5°C), CO2 elevation (700 μmol mol−1) and varying water regimes (high to low water content) on physiological responses and biomass growth of reed canary grass (Phalaris arundinacea L., local field-grown cultivar) grown in a boreal environment. In controlled environment greenhouses, various physiological and growth parameters of grass, i.e., light-saturated net photosynthetic rates (P nmax), water use efficiency (WUE) and optimal photochemical efficiency of photosystem II (F v/F m), and leaf area development and biomass of plant organs (leaf, stem, coarse, and fine root) were measured. During the early measurement periods, elevated temperature enhanced leaf photosynthesis and above-ground biomass of reed canary grass; however, this resulted in earlier senescence and lower biomass at the end of measurement period, compared to ambient temperature. This effect was more pronounced under water limitation. Elevated CO2 enhanced P nmax, WUE, and leaf area and total plant biomass (above- and below-ground) over growing season. The explanation for imbalance between stimulated photosynthesis and increase in above-ground biomass was that CO2 enrichment causes a greater increase in the plant’s root system. The combination of elevated temperature and CO2 slightly increases the growth of plant. Adequate water availability favored photosynthesis and biomass growth of reed canary grass. The temperature- and drought-induced stresses were partially mitigated by elevated CO2. Other cultivars should be tested in order to identify those that are better adapted to elevated temperatures and CO2 and variable water levels. 相似文献
98.
Survival of Mycobacterium avium, Legionella pneumophila, Escherichia coli, and Caliciviruses in Drinking Water-Associated Biofilms Grown under High-Shear Turbulent Flow 下载免费PDF全文
99.
100.
Amanda R. Decker Matthew S. McNeill Aaron M. Lambert Jeffrey D. Overton Yu-Chia Chen Ramón A. Lorca Nicolas A. Johnson Susan E. Brockerhoff Durga P. Mohapatra Heather MacArthur Pertti Panula Mark A. Masino Loren W. Runnels Robert A. Cornell 《Developmental biology》2014
Transient receptor potential, melastatin-like 7 (Trpm7) is a combined ion channel and kinase implicated in the differentiation or function of many cell types. Early lethality in mice and frogs depleted of the corresponding gene impedes investigation of the functions of this protein particularly during later stages of development. By contrast, zebrafish trpm7 mutant larvae undergo early morphogenesis normally and thus do not have this limitation. The mutant larvae are characterized by multiple defects including melanocyte cell death, transient paralysis, and an ion imbalance that leads to the development of kidney stones. Here we report a requirement for Trpm7 in differentiation or function of dopaminergic neurons in vivo. First, trpm7 mutant larvae are hypomotile and fail to make a dopamine-dependent developmental transition in swim-bout length. Both of these deficits are partially rescued by the application of levodopa or dopamine. Second, histological analysis reveals that in trpm7 mutants a significant fraction of dopaminergic neurons lack expression of tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis. Third, trpm7 mutants are unusually sensitive to the neurotoxin 1-methyl-4-phenylpyridinium, an oxidative stressor, and their motility is partially rescued by application of the iron chelator deferoxamine, an anti-oxidant. Finally, in SH-SY5Y cells, which model aspects of human dopaminergic neurons, forced expression of a channel-dead variant of TRPM7 causes cell death. In summary, a forward genetic screen in zebrafish has revealed that both melanocytes and dopaminergic neurons depend on the ion channel Trpm7. The mechanistic underpinning of this dependence requires further investigation. 相似文献