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   124篇
  免费   7篇
儿科学   24篇
妇产科学   6篇
基础医学   8篇
口腔科学   1篇
临床医学   12篇
内科学   29篇
皮肤病学   1篇
特种医学   1篇
外科学   4篇
综合类   3篇
预防医学   35篇
药学   3篇
肿瘤学   4篇
  2023年   1篇
  2022年   5篇
  2021年   7篇
  2020年   4篇
  2019年   4篇
  2018年   1篇
  2017年   1篇
  2016年   6篇
  2015年   7篇
  2014年   5篇
  2013年   8篇
  2012年   9篇
  2011年   7篇
  2010年   4篇
  2009年   5篇
  2008年   12篇
  2007年   8篇
  2006年   7篇
  2005年   12篇
  2004年   7篇
  2003年   5篇
  2002年   2篇
  1999年   1篇
  1998年   1篇
  1986年   2篇
排序方式: 共有131条查询结果,搜索用时 15 毫秒
1.
Endophytic fungi are known to play an important role in driving the evolution of plants by conferring adaptational advantages to their host through the production of secondary metabolites and phytohormones. In this study, we evaluated the diversity and phylogenetic relationship of endophytic fungal communities from four Dendrobium species viz., Dendrobium chrysanthum, Dendrobium heterocarpum, Dendrobium hookerianum, and Dendrobium longicornu of Meghalaya, India. A total of 51 culturable endophytic fungi were isolated from the four selected orchid species. The isolates were identified based on nuclear large subunit sequences into 33 species. Approximately 91% of the isolates showed affinity to Ascomycetes, while 9% of the isolates showed BLAST search similarity to Basidiomycetes. The most common genera were Trichoderma and Xylaria. The most prevalent genera were Fusarium, which was detected in all the four Dendrobium species followed by Diaporthe, which was present in three Dendrobium species viz., D. chrysanthum, D. hookerianum, and D. heterocarpum. The Shannon index value of endophytic fungal communities was the highest in D. chrysanthum (2.66), while D. longicornu (1) had the highest Evenness index. The present study revealed that endophytic fungi in these orchids are an amalgam of pathogenic and beneficial fungi, which have, at the least, switched their lifestyle to asymptomatic endophyte in their host. To our knowledge, this is the first such report on the diversity of endophytic fungi in the four selected Dendrobium species from Meghalaya, India.  相似文献   
2.
3.
4.
Herein, we report the first synthesis of covalent triazine-based frameworks (CTFs) based on a hexanitrile monomer, namely the novel pseudo-octahedral hexanitrile 1,4-bis(tris(4′-cyano-phenyl)methyl)benzene 1 using both ionothermal reaction conditions with ZnCl2 at 400 °C and the milder reaction conditions with the strong Brønsted acid trifluoromethanesulfonic acid (TFMS) at room temperature. Additionally, the hexanitrile was combined with different di-, tri-, and tetranitriles as a second linker based on recent work of mixed-linker CTFs, which showed enhanced carbon dioxide captures. The obtained framework structures were characterized via infrared (IR) spectroscopy, elemental analysis, scanning electron microscopy (SEM), and gas sorption measurements. Nitrogen adsorption measurements were performed at 77 K to determine the Brunauer-Emmett-Teller (BET) surface areas range from 493 m2/g to 1728 m2/g (p/p0 = 0.01–0.05). As expected, the framework CTF-hex6 synthesized from 1 with ZnCl2 possesses the highest surface area for nitrogen adsorption. On the other hand, the mixed framework structure CTF-hex4 formed from the hexanitrile 1 and 1,3,5 tricyanobenzene (4) shows the highest uptake of carbon dioxide and methane of 76.4 cm3/g and 26.6 cm3/g, respectively, at 273 K.  相似文献   
5.
6.
Some evidence suggests that balanced energy protein (BEP) supplements taken during pregnancy and lactation can have positive effects on birth outcomes such as small‐for‐gestational age and birthweight, but more evidence is needed on the long‐term use and acceptability of such supplements. We conducted a mixed‐methods formative research study to assess and compare compliance with and acceptability of two BEP supplements, a lipid‐based peanut paste and a biscuit, to identify BEP supplements for subsequent inclusion in an efficacy trial. We conducted an 8‐week feeding trial of daily supplementation among two groups of 40 pregnant women each in rural Nepal. Compliance data were collected and supplements distributed at the weekly visits. Sensory properties of the supplements were assessed using a 7‐point Likert scale. In addition, in‐depth interviews with women (n = 16), family members (n = 6) and health workers (n = 6) and focus group discussions (FGDs) (n = 4) were conducted to explore themes related to general use and intention of future use of the supplement. Overall self‐reported compliance was high: medians of 91.1% in the lipid‐based peanut paste group and 96.4% in the biscuit group. Both supplements were rated highly on overall likability (median score 6/7) and sensory properties. Qualitative findings showed that sustained use of the supplements was attributed to expected health benefits, favourable sensory attributes, and family support. The FGDs suggested providing the option to choose between more than one type/flavour of supplements to improve compliance. Sharing was mostly evident in the first week with higher sharing reported in the biscuit group.  相似文献   
7.
Pregnant women in developing countries are vulnerable to multiple micronutrient deficiencies. We investigated their prevalence and seasonal variation as part of a baseline assessment in a population-based, maternal micronutrient supplementation trial conducted in the rural Southeastern plains of Nepal. Serum concentrations of 11 micronutrients were assessed in 1165 pregnant women in the 1st trimester before supplementation. Using defined cutoff values, the prevalence of deficiencies of vitamins A, E, and D were 7, 25, and 14%, respectively. Nearly 33% of the women were deficient in riboflavin, and 40 and 28% had serum vitamin B-6 and B-12 deficiencies, respectively. Only 12% of the women were folate deficient, but 61% were zinc deficient. The prevalence of low serum iron concentration was 40%, and 33% were anemic (hemoglobin < 110 g/L). Multiple micronutrient deficiencies were common among pregnant women. Over 10% of the pregnant women were both anemic and deficient in B-complex vitamins, whereas 22% of women were both anemic and zinc deficient. Only 4% of women had no deficiency, whereas approximately 20% of the women had 2, 3, or 4 deficiencies. Almost 18% of women had >/=5 deficiencies. Micronutrient status varied by season; it was generally best during the winter months, except for serum vitamin D concentration, which peaked during the hot summer and monsoon months. Women in rural South Asia are likely to begin a pregnancy with multiple micronutrient deficiencies that may vary with seasonality in micronutrient-rich food availability.  相似文献   
8.
9.
10.
Total mercury levels were quantified in Tilapia mossambicus, Cirrhinus mrigela and Labio rohita, captured from East Calcutta Wetlands and Titagarh sewage fed aquaculture ponds. The bioconcentration factor of collected fish was assessed. Total mercury level ranged from 0.073 to 0.94 μg/g in both pre and post monsoon season. T. mossambicus in both season and C. mrigela at pre monsoon, cross the Indian recommended maximum limit (0.50 μg/g wet weight) for food consumption and according to World Health Organization guidelines all fish were not recommended for pregnant women and individuals under 15 years ages. A significant correlation was observed between mercury content of aquaculture pond water and fish muscle tissue. Total mercury concentration in experimental sites were higher than the control area (Wilcoxon Ranked-Sum test p > 0.05), which suggested the connection between mercury bioaccumulation and sewage fed aquaculture.  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