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161.
The Pannonian plain as a source of <Emphasis Type="Italic">Ambrosia</Emphasis> pollen in the Balkans
B. Šikoparija M. Smith C. A. Skjøth P. Radišić S. Milkovska S. Šimić J. Brandt 《International journal of biometeorology》2009,53(3):263-272
This study aims to find likely sources of Ambrosia pollen recorded during 2007 at five pollen-monitoring sites in central Europe: Novi Sad, Ruma, Negotin and Nis (Serbia) and
Skopje (Macedonia). Ambrosia plants start flowering early in the morning and so Ambrosia pollen grains recorded during the day are likely to be from a local source. Conversely, Ambrosia pollen grains recorded at night or very early in the morning may have arrived via long-range transport. Ambrosia pollen counts were analysed in an attempt to find possible sources of the pollen and to identify Ambrosia pollen episodes suitable for further investigation using back-trajectory analysis. Diurnal variations and the magnitude of
Ambrosia pollen counts during the 2007 Ambrosia pollen season showed that Novi Sad and Ruma (Pannonian Plain) and to a lesser degree Negotin (Balkans) were located near
to sources of Ambrosia pollen. Mean bi-hourly Ambrosia pollen concentrations peaked during the middle of the day, and concentrations at these sites were notably higher than at
Nis and Skopje. Three episodes were selected for further analysis using back-trajectory analysis. Back-trajectories showed
that air masses brought Ambrosia pollen from the north to Nis and, on one occasion, to Skopje (Balkans) during the night and early morning after passing to
the east of Novi Sad and Ruma during the previous day. The results of this study identified the southern part of the Pannonian
Plain around Novi Sad and Ruma as being a potential source region for Ambrosia pollen recorded at Nis and Skopje in the Balkans. 相似文献
162.
C. A. Skjøth M. Smith J. Brandt J. Emberlin 《International journal of biometeorology》2009,53(1):75-86
Birch pollen is highly allergenic. Knowledge of daily variations, atmospheric transport and source areas of birch pollen is
important for exposure studies and for warnings to the public, especially for large cities such as London. Our results show
that broad-leaved forests with high birch tree densities are located to the south and west of London. Bi-hourly Betula pollen concentrations for all the days included in the study, and for all available days with high birch pollen counts (daily
average birch pollen counts >80 grains/m3), show that, on average, there is a peak between 1400 hours and 1600 hours. Back-trajectory analysis showed that, on days
with high birch pollen counts (n = 60), 80% of air masses arriving at the time of peak diurnal birch pollen count approached North London from the south in
a 180 degree arc from due east to due west. Detailed investigations of three Betula pollen episodes, with distinctly different diurnal patterns compared to the mean daily cycle, were used to illustrate how
night-time maxima (2200–0400 hours) in Betula pollen counts could be the result of transport from distant sources or long transport times caused by slow moving air masses.
We conclude that the Betula pollen recorded in North London could originate from sources found to the west and south of the city and not just trees within
London itself. Possible sources outside the city include Continental Europe and the Betula trees within the broad-leaved forests of Southern England. 相似文献
163.
C Härtel K Faust S Avenarius B Bohnhorst M Emeis C Gebauer P Groneck F Heitmann T Hoehn M Hubert A Kribs H Küster R Laux M Mögel D Müller D Olbertz C Roll J Siegel A Stein M Vochem U Weller A von der Wense C Wieg J Wintgens C Hemmelmann A Simon E Herting W Göpel;German Neonatal Network 《PloS one》2012,7(6):e38304
164.
165.
KC Lødrup Carlsen S Roll KH Carlsen P Mowinckel AH Wijga B Brunekreef M Torrent G Roberts SH Arshad I Kull U Krämer A von Berg E Eller A Høst C Kuehni B Spycher J Sunyer CM Chen A Reich A Asarnoj C Puig O Herbarth JM Mahachie John K Van Steen SN Willich U Wahn S Lau T Keil;GALEN WP . ‘Birth Cohorts’ working group 《PloS one》2012,7(8):e43214
Objective
To examine the associations between pet keeping in early childhood and asthma and allergies in children aged 6–10 years.Design
Pooled analysis of individual participant data of 11 prospective European birth cohorts that recruited a total of over 22,000 children in the 1990s.Exposure definition
Ownership of only cats, dogs, birds, rodents, or cats/dogs combined during the first 2 years of life.Outcome definition
Current asthma (primary outcome), allergic asthma, allergic rhinitis and allergic sensitization during 6–10 years of age.Data synthesis
Three-step approach: (i) Common definition of outcome and exposure variables across cohorts; (ii) calculation of adjusted effect estimates for each cohort; (iii) pooling of effect estimates by using random effects meta-analysis models.Results
We found no association between furry and feathered pet keeping early in life and asthma in school age. For example, the odds ratio for asthma comparing cat ownership with “no pets” (10 studies, 11489 participants) was 1.00 (95% confidence interval 0.78 to 1.28) (I2 = 9%; p = 0.36). The odds ratio for asthma comparing dog ownership with “no pets” (9 studies, 11433 participants) was 0.77 (0.58 to 1.03) (I2 = 0%, p = 0.89). Owning both cat(s) and dog(s) compared to “no pets” resulted in an odds ratio of 1.04 (0.59 to 1.84) (I2 = 33%, p = 0.18). Similarly, for allergic asthma and for allergic rhinitis we did not find associations regarding any type of pet ownership early in life. However, we found some evidence for an association between ownership of furry pets during the first 2 years of life and reduced likelihood of becoming sensitized to aero-allergens.Conclusions
Pet ownership in early life did not appear to either increase or reduce the risk of asthma or allergic rhinitis symptoms in children aged 6–10. Advice from health care practitioners to avoid or to specifically acquire pets for primary prevention of asthma or allergic rhinitis in children should not be given. 相似文献166.
Jens Øbro Bernhard Borkhardt Jesper Harholt Michael Skjøt William G. T. Willats Peter Ulvskov 《Transgenic research》2009,18(6):961-969
Despite the wide occurrence of pectin in nature only a few source materials have been used to produce commercial pectins.
One of the reasons for this is that many plant species contain pectins with high levels of neutral sugar side chains or that
are highly substituted with acetyl or other groups. These modifications often prevent gelation, which has been a major functional
requirement of commercial pectins until recently. We have previously shown that modification of pectin is possible through
heterologous expression of pectin degrading enzymes in planta. To test the effect of simultaneous modification of the two main neutral pectic side chains in pectic rhamnogalacturonan
I (RGI), we constitutively expressed two different enzymes in Arabidopsis thaliana that would either modify the galactan or the arabinan side chains, or both side chains simultaneously. Our analysis showed
that the simultaneous truncation of arabinan and galactan side chains is achievable and does not severely affect the growth
of Arabidopsis thaliana. 相似文献
167.
168.
Background
PhiC31 integrase facilitates efficient integration of transgenes into human and mouse genomes and is considered for clinical gene therapy. However recent studies have shown that the enzyme can induce various chromosomal abnormalities in primary human embryonic cells and mammalian cell lines. The mechanisms involved are unknown, but it has been proposed that PhiC31 attachment sites in the host genome recombine leading to chromosomal translocations. 相似文献169.
Determination of the diadic composition of alginate by means of circular dichroism: a fast and accurate improved method 总被引:5,自引:0,他引:5
Donati I Gamini A Skjåk-Braek G Vetere A Campa C Coslovi A Paoletti S 《Carbohydrate research》2003,338(10):1139-1142
Circular dichroism (CD) is presented as a reliable and sensitive method of determining the diadic frequency composition of alginate (F(GG), F(MM) and F(GM+MG)). The availability of samples, very largely or even completely conforming to the limiting structures of polymannuronate (MM)(n), polyguluronate (GG)(n) and polyalternating MG (MG)(n), respectively, allowed the limiting CD spectra for each alginate diad to be obtained. These showed very different CD behaviour, thus pointing out the crucial importance of the neighbouring residue in chiroptical properties. Using an iterative best-fit procedure, the diadic composition of commercial alginates could be obtained from their respective CD spectra by means of a linear combination of the spectra of the three limiting diads. The results were found in excellent agreement with the composition parameters obtained by 1H NMR spectroscopy. 相似文献
170.
Ramstadab MV Markussen S Ellingsen TE Skjåk-Braek G Levine DW 《Enzyme and microbial technology》2001,28(1):57-69
The mannuronan C-5-epimerase AlgE2 is one of a family of Ca(2+)-dependent epimerases secreted by Azotobacter vinelandii. These enzymes catalyze the conversion of beta-D-mannuronic acid residues (M) to alpha-L-guluronic acid residues (G) in alginate. AlgE2 had a pH optimum between 6.5 and 7 and a temperature optimum around 55 degrees C. Addition of low molecular weight organic compounds, including buffers, amino acids and osmoprotective compounds, affected the activity of the enzyme. The charge, size and stereochemistry of the added compounds were important. The activity of AlgE2, dissolved in various buffers (same pH), decreased with increasing fraction of positively charged buffer ions. Mono- and divalent metal ions also influenced the activity. When Ca(2+) was omitted only Sr(2+), of the metal ions tested, supported some activity of AlgE2. At high concentration of Ca(2+) (3.3 mM) these ions had a negative effect on the activity, whereas at low Ca(2+) concentration (0.58 mM) the activity was enhanced by addition of Sr(2+), and to some degree also by addition of Mg(2+) and Mn(2+). During epimerization AlgE2 occasionally causes cleavage of the alginate chain. These chain breaks could not be prevented by changes in the conditions during the epimerization. The composition and sequential structure of epimerized alginate was not altered by changes in the epimerization conditions. 相似文献