首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   120篇
  免费   8篇
  2022年   1篇
  2021年   5篇
  2020年   10篇
  2019年   8篇
  2018年   13篇
  2017年   6篇
  2016年   8篇
  2015年   6篇
  2014年   10篇
  2013年   7篇
  2012年   3篇
  2011年   10篇
  2010年   7篇
  2009年   4篇
  2008年   8篇
  2007年   6篇
  2006年   2篇
  2005年   1篇
  2004年   1篇
  2002年   4篇
  2000年   3篇
  1999年   1篇
  1998年   1篇
  1988年   1篇
  1982年   1篇
  1981年   1篇
排序方式: 共有128条查询结果,搜索用时 15 毫秒
121.
Ferula cupularis (Boiss.) Spalik et S. R. Downie is an endangered endemic Iranian medicinal plant with occurrence restricted to Fars and Kohkilooyeh Boyerahmad provinces, Iran. F. cupularis is cited for strong antibacterial activity, usages in foodstuffs preservation, and has long been used by local peoples for ulcer treatment. In this research, the aerial parts of F. cupularis wild populations were collected from three natural habitats: Eqlid-Kaftar (FC1), Kakan (FC2), and Sepidan-Komohr (FC3), to assess phytochemical diversity and antioxidant activity. The quantity of essential oil (EO) ranged remarkably from 0.42 to 0.72 % v/w among the populations. Results obtained from the EO analysis by GC-FID and GC/MS detected up to 56 compounds. α-Pinene (21.65–31.53 %), sabinene (4.74–11.39 %), phellandrene (1.78–5.1 %), δ-3-carene (1.85–7.18 %), limonene (4.12–7.45 %), (Z)-β-ocimene (9.08–17.64 %), and elemicin (0.23–5.74 %) were the major compounds of EOs varied significantly among the populations. Moreover, total phenol content (250.54 to 387.45 mg gallic acid/100 g dry weight (DW)) and flavonoids (34.38 to 41.12 mg quercetin/100 g DW) of methanolic extracts varied substantially among the populations. Antioxidant activities of F. cupularis EOs and extracts were assessed by DPPH (2,2,1-diphenyl-1-picrylhydrazyl) radical scavenging method. EOs exhibited EC50 values ranging from 8.88 to 9.67 μg mL−1 and the EC50 values for the extract ranged from 941.36 to 1335.96 μg mL−1 within the populations. Results demonstrated significantly different levels of antioxidant capacities among the studied populations. Monitoring the data, the population collected from Eqlid-Kaftar (FC1) was selected as the most potent population concerning the highest EO content and antioxidant activity level. The obtained data provided new insights for an initial source of breeding plans and ultimately massive production for food and pharmaceutical industries.  相似文献   
122.
123.
124.
Prosopis glandulosa var. torreyana accounts for nearly 90% of the total plant cover in a mesquite woodland community near Harper's Well along the southern margin of the Salton Sea in the Sonoran Desert of California. Total above-ground biomass in ten individuals studied in detail ranged from 43–760 kg per plant and 1.9–8.5 kg m-2 canopy area. Stand biomass ranged locally from a high of 23,000 kg ha-1 near the wash to 3,500 kg ha-1 in the fringe of this mesquite stand. Net above-ground primary production for 1980 had a mean of 2.2 kg m-2 canopy for shrub forms and 5.3 kg m-2 canopy for tree forms. Mean Prosopis stand production for 1980 was 3,650 kg ha-1, an extremely high value for desert communities. This level of production is particularly high in relation to the low mean annual precipitation of approximately 70 mm. New woody tissues in trunk and branches accounted for 51.5% of the allocation of productivity in Prosopis, a remarkably high woody allocation for a desert plant. Only 33.6% of net primary production was allocated to leaves.  相似文献   
125.
The low stability of recombinant human interferon-γ (rhIFN-γ) therapeutic protein imposes some restrictions in its medical applications. In the current study, the effect of oxygen tension on the stability of purified rhIFN-γ was investigated. The rhIFN-γ was purified (>99%) by a two-step chromatographic process. Storage vials were filled by purified formulated product under normal atmospheric oxygen and low oxygen tension conditions. At different time intervals, the amounts of rhIFN-γ covalent dimers and deamidated forms were analyzed using analytical high-performance liquid chromatography (HPLC; size exclusion and cation exchange) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) methods. To determine the biological activity of purified rhIFN-γ, an antiviral activity assay against vesicular stomatitis virus (VSV) was performed. Upon rhIFN-γ long-term storage in a low oxygen tension condition, the amounts of rhIFN-γ covalent dimers and deamidated forms and also the biological activity of rhIFN-γ changed a little. In contrast, by 9 months of storage of rhIFN-γ preparations under normal atmospheric condition, the amount of covalent dimers and deamidated forms increased with time and reached to approximately 3.5% and 11.5% of the initial amount, respectively. The antiviral specific activity of 9-month-old rhIFN-γ preparations decreased to 41% of the initial amount at normal storage condition, while no significant reduction was seen at the low oxygen tension condition. In conclusion, oxygen tension during storage could have a significant impact on rhIFN-γ stability and finally on the quality of pharmaceutical rhIFN-γ product.  相似文献   
126.
This study tested the effectiveness of laser biostimulation in small-scale cultures in vitro. We investigated the response of recombinant CHO cells, which are used for the production of monoclonal antibody, to low level laser radiation. The cells were irradiated using a 632.8 nm He–Ne laser in a continuous wave mode at different energy doses. We incubated the irradiated cells in small batch cultures and assessed their proliferation and productivity at various time intervals. Compared to untreated cells, the irradiated cells showed a significant increase in antibody production. Moreover, the results showed that laser irradiation did not affect viability and slightly enhanced proliferation rate.  相似文献   
127.
128.
Abstract

Perceptions of the populace play a central and decisive role in advancing pro-environmental policies. To study attitudes and perceptions towards environmental measures, we apply several items of New Ecological Paradigm (NEP) and Value-Belief-Norm (VBN) theories to cross-examine the public perceptions of climate change in the urban city-state of Singapore through analysis of quantitative questionnaires and qualitative semi-structured interviews. The perceptions were explored about ecological orientation (two dimensions of NEP: level of concern, self-reported knowledge) and environmental behavior (two dimensions of VBN: acceptance and support of national adaptation measures, confidence in adaptation). There is a moderate to high concern for climate change, in general, and sea level rise and flooding, in particular, and the concern is expected to increase in the future. Individuals who indicated a higher level of concern are likely to be more accepting and supportive of climate change measures. Also, while the majority of the populace are amenable to legislative measures from the government, such as enacting pro-environmental laws and more are agreeable to accepting cuts on living standards, as opposed to paying more in prices and taxes. Ecological orientation does not translate directly into environmental behavior, highlighting the gulf between perception and behavior in Singapore.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号