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  • Wiley  (23)
  • 2020-2024
  • 2020-2022  (5)
  • 2015-2019  (18)
  • 1
    Publikationsdatum: 2015-11-07
    Beschreibung: Desertification is becoming a major ecological concern in arid and semi-arid regions, especially under climate change. Globally, it is burning up lands for human habitats with a rapidly spreading tendency. Many scientists have been struggling to explore the related mechanisms. Challenges remain in revealing the fundamental principle in terms of desert-oasis interactions that are associated with nonstationary variations. Here we present a theory of desertification dynamics through examining nonstationary effects of climate change and human interference. We hypothesize that such dynamics can be described as the fate and transport of dry air mass continuously generated from desert. We simulate a region in northwestern China and reveal that dynamics of the nonstationary desertification process is subject to interactive impacts from a variety of factors. Our study moves forward the field of desertification studies through initiation of the dynamics and nonstationarity concepts which allow the fundamental mechanism be disclosed.
    Print ISSN: 0148-0227
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2019
    Beschreibung: ABSTRACT Understanding the distribution of C3 and C4 plants and its forcing mechanisms since the Last Glacial Maximum (LGM) is important for anticipating their possible response to future climate change. The spatiotemporal pattern of C4 plant abundance on the Chinese Loess Plateau (CLP) is complex and the dominant causal factors are contentious. Here, we use δ13C records of organic matter in paleosols from the CLP to reconstruct changes in the representation of C4 plants since the LGM. The results indicate that the relative abundance of C4 plants increased after the LGM, reaching a maximum during 10–6 ka bp, and then decreased. Spatially, the representation of C4 plants was characterized by increasing values from north‐west to south‐east. In addition, the smallest spatial difference (∼10%) in the representation of C4 plants between the north‐west and south‐east parts of the CLP was during the LGM, and the largest difference (∼30%) was during the early Holocene. We combined our findings with output from the BIOME4 model to study the sensitivity of C4 plants to changes in climate and atmospheric CO2 concentration. The results suggest that increasing temperature was the dominant factor driving C4 plant expansion on the CLP since the LGM.
    Print ISSN: 0267-8179
    Digitale ISSN: 1099-1417
    Thema: Geographie , Geologie und Paläontologie
    Publiziert von Wiley
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2017-08-10
    Beschreibung: Ovarian cancer is the most common malignancy in women. Owing to late syndromic presentation and lack of efficient early detection, most cases are diagnosed at advanced stages. Surgery and platinum-based chemotherapy are still the standard care currently. However, resistance invoked often compromises the clinical value of the latter. Expression of DNA methyltransferase 1 (DNMT1) was analysed by gene array. Protein was determined by immunoblotting. Exosome was isolated with commercial kit. Cell proliferation was measured by CCK8 method. Annexin V-PI double staining was performed for apoptosis evaluation. Xenograft model was established and administrated with exosome. Tumour growth and overall survival were monitored. We demonstrated the upregulation of DNMT1 in both tumour and derived cell line. DNMT1 transcripts were highly enriched in exosomes from conditioned medium of ovarian cells. Co-incubation with exosomes stimulated endogenous expression and rendered host cell the resistance to cytotoxicity of cisplatin. In vivo administration of DNMT1-containing exosomes exacerbated xenograft progression and reduced overall survival significantly. Moreover, treatment with exosome inhibitor GW4869 almost completely restored sensitivity in resistant cells. Our data elucidated an unappreciated mechanism of exosomal DNMT1 in cisplatin resistance in ovarian cancer, also indicating the potential of the combination of exosome inhibitor with cisplatin in resistant patients.
    Print ISSN: 0263-6484
    Digitale ISSN: 1099-0844
    Thema: Biologie , Medizin
    Publiziert von Wiley
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2017-12-02
    Beschreibung: A series of V-MCM-41 were in situ synthesized. The textual properties and vanadium species were systematically characterized. The results showed that the catalysts could still maintain mesoporous structure and high specific surface area. The vanadium species were highly dispersed on the surface while polymeric vanadium species co-existed. The iso-butane dehydrogenation was performed by employing CO 2 as soft oxidant. The results revealed an almost linear relationship between the activity and surface vanadium sites. Isolated vanadium species were more active for iso-butane dehydrogenation. The iso-butane dehydrogenation reaction in the presence of CO 2 could proceed simultaneously via oxidative dehydrogenation and non-oxidative dehydrogenation followed by the reverse water gas shift reaction.
    Print ISSN: 0930-7516
    Digitale ISSN: 1521-4125
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Publiziert von Wiley
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Publikationsdatum: 2017-12-22
    Beschreibung: Drought is a major natural hazard that has massive impacts on the society. How to monitor drought is critical for its mitigation and early warning. This study proposed a modified version of the multivariate standardized drought index (MSDI) based on precipitation, evapotranspiration, and soil moisture, i.e. modified multivariate standardized drought index (MMSDI). This study also used nonparametric joint probability distribution analysis. Comparisons were done between standardized precipitation evapotranspiration index (SPEI), standardized soil moisture index (SSMI), MSDI, and MMSDI, and real-world observed drought regimes. Results indicated that MMSDI detected droughts that SPEI and/or SSMI failed to do. Also, MMSDI detected almost all droughts that were identified by SPEI and SSMI. Further, droughts detected by MMSDI were similar to real-world observed droughts in terms of drought intensity and drought-affected area. When compared to MMSDI, MSDI has the potential to overestimate drought intensity and drought-affected area across China, which should be attributed to exclusion of the evapotranspiration components from estimation of drought intensity. Therefore, MMSDI is proposed for drought monitoring that can detect agrometeorological droughts. Results of this study provide a framework for integrated drought monitoring in other regions of the world and can help to develop drought mitigation.
    Print ISSN: 0148-0227
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2017-10-31
    Beschreibung: Cation exchange capacity (CEC) helps soils hold nutrients and buffer pH, making it vital for maintaining basic function of terrestrial ecosystems. However, little is known about the temporal dynamics of CEC over broad geographical scales. In this study, we used Random Forest method to compare historical CEC data from the 1980s with new data from the 2010s across northern China's grasslands. We found that topsoil CEC in the 2010s was significantly lower than in the 1980s, with an overall decline of about 14%. Topsoil CEC decreased significantly in alpine meadow, alpine steppe, meadow steppe, and typical steppe by 11%, 20%, 27% and 9% respectively. Desert steppe was the only ecosystem type which experienced no significant change. CEC was positively related to soil carbon content, silt content, and mean annual precipitation, suggesting that the decline was potentially associated with soil organic carbon loss, soil degradation, soil acidification, and extreme precipitation across northern China's grasslands since the 1980s. Overall, our results demonstrate topsoil CEC loss due to environmental changes, which may alter the vegetation community composition and its productivity and thus trigger grassland dynamics under a changing environment.
    Print ISSN: 0148-0227
    Thema: Biologie , Geologie und Paläontologie
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 2016-01-14
    Beschreibung: Four new pregnane steroids, aglaiasterols A–D ( 1 – 4 ), have been isolated from the EtOH extract of stems of Aglaia abbreviata. They were identified as (3 α ,5 α ,17 Z )-3-hydroxypregn-17-en-16-one ( 1 ), (3 β ,5 α ,17 E )-3-hydroxypregn-17-en-16-one ( 2 ), (3 β ,5 α ,17 Z )-3-hydroxypregn-17-en-16-one ( 3 ), and (3 α ,5 α ,20 S* )-3-hydroxy-16-oxopregnan-20-yl acetate ( 4 ) on the basis of spectroscopic methods, including 1D- and 2D-NMR techniques. Compounds 1 – 4 were evaluated for their cytotoxic activities against K562 (human leukemia), MCF-7 (human breast cancer), and KB (human oral epithelium cancer) cells, and drug-resistant cells of K562/A02, MCF-7/ADM, and KB/VCR. These isolates showed weak to moderate inhibitory effects on the growth of the tested cell lines.
    Print ISSN: 0018-019X
    Digitale ISSN: 1522-2675
    Thema: Chemie und Pharmazie
    Publiziert von Wiley
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 2018-02-25
    Beschreibung: Non-analogous climates (NACs), climates without modern analogs on Earth, challenge our understanding of eco-evolutionary processes that shape global biodiversity, particularly because of their propensity to promote novel ecosystems. However, NAC studies are generally inadequate and partial. Specifically, systematic comparisons between the future and the past are generally lacking, and hydraulic NACs tend to be underemphasized. In the present study, by adopting a frequency-distribution based method that facilitates the procedures of contributions parsing and conducting multiple comparisons, we provide a global overview of multi-dimensional NACs for both the past and the future within a unified framework. We show that NACs are globally prevalent, covering roughly half of the land area across the time-periods under investigation, and have a high degree of spatial structure. Patterns of NACs differ dramatically between the past and the future. Hydraulic NACs are more complex both in spatial patterns and in major contributions of variables than are thermal NACs. However, hydraulic NACs are more predictable than originally thought. Generally, hydraulic NACs in the future (2100 AD) exhibit comparable predictability to thermal NACs in the last glacial maximum (LGM) (21k BP). Identifying these NAC patterns has potential implications on climate-adaptive managements and preparing in advance to possibly frequent novel ecosystems. However, a learning-from-the-past strategy might be of limited utility for management under present circumstances. This article is protected by copyright. All rights reserved.
    Print ISSN: 1354-1013
    Digitale ISSN: 1365-2486
    Thema: Biologie , Energietechnik , Geographie
    Publiziert von Wiley
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2019-07-29
    Print ISSN: 1639-4488
    Digitale ISSN: 1751-908X
    Thema: Geologie und Paläontologie
    Publiziert von Wiley
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2016-02-23
    Beschreibung: In this study, the regional tree-ring chronology of Picea crassifolia was used to estimate annual (September to August) streamflow of the Shiyang River for the period from AD 1765 to 2010. The linear regression model was stable and could explain 41.5% of the variance for the calibration period of 1955–2005. According to the streamflow reconstruction, dry periods with below average streamflow occurred in AD 1775–1804, 1814–1823, 1831–1856, 1862–1867, 1877–1885, 1905–1910, 1926–1932, 1948–1951, 1960–1963 and 1989–2002. Periods of relatively wet years are identified for AD 1765–1774, 1805–1813, 1824–1830, 1857–1861, 1868–1876, 1886–1904, 1911–1925, 1933–1947, 1952–1959, 1964–1988 and 2003–2010. Comparisons with the precipitation reconstructions from surrounding areas supplied a high degree of confidence in our reconstruction. Our reconstructed streamflow is significantly correlated with sea surface temperature in the eastern equatorial Pacific Ocean and the North Atlantic Ocean. The Multitaper spectral and correlation analyses also suggested that the reconstructed streamflow variation in the Shiyang River could be associated with large-scale atmospheric-oceanic variability, such as El Niño-Southern Oscillation (ENSO). The linkages among the streamflow reconstruction, NAO and ENSO suggest the connection of regional streamflow variations to the Asian monsoon and westerlies circulations. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
    Print ISSN: 0885-6087
    Digitale ISSN: 1099-1085
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie
    Publiziert von Wiley
    Standort Signatur Erwartet Verfügbarkeit
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