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   175篇
  免费   4篇
  179篇
  2023年   2篇
  2022年   7篇
  2021年   9篇
  2020年   3篇
  2019年   5篇
  2018年   2篇
  2017年   2篇
  2016年   10篇
  2015年   13篇
  2014年   11篇
  2013年   10篇
  2012年   11篇
  2011年   8篇
  2010年   7篇
  2009年   6篇
  2008年   11篇
  2007年   8篇
  2006年   9篇
  2005年   10篇
  2004年   5篇
  2003年   7篇
  2002年   4篇
  2001年   3篇
  2000年   2篇
  1999年   1篇
  1998年   2篇
  1997年   1篇
  1995年   2篇
  1993年   3篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1979年   2篇
排序方式: 共有179条查询结果,搜索用时 15 毫秒
1.
Nanobiotechnology is a fast growing field in which instruments are created by nano size particles of approximately 1 to 100 nm (1 to 100 nm) of the scale of nanometers. Nanoparticles today have potential implications for life sciences and human health applications. In this research, silver nanoparticles (AgNPs) were successfully synthesized using Saussurea costus root aqueous extract and AgNPs have been characterized by the use of UV–Vis, Scanning Electron Microscopes (SEM), and Electromicroscopy of transmission (TEM) and Energy Dispersive X-ray Spectroscopy (EDXs). The highest number of particles are in the 5 to 15 nm range. AgNPs have been added in saffron dye solution for degradation dye biosynthesizing, and product analysis using UV/vision spectrophotometer, FTIR and HPLC has been performed. Green-summed AgNPs effectively degraded the color, with UV/VIS spectrophotometers, around 84.6 percent at 72 h of exposure time. The decrease in tested dye and presence of multiple new highs in the samples treated with different retention times (Rt) 2.30, 6.10 and 12.24 min, is positive for the biodegradation compared to the untreated dye with single high at 10.31 min, respectively. This green chemistry is very advantageous for AgNPs biosynthesis, for example, cost-effectiveness and usability for medicinal, pharmaceutical and extensive industrial applications. Furthermore, the bio-recovery unit for plant extracts provides a greater ease of handling, compared to micro-organisms.  相似文献   
2.
Abouthiouzine is a newly synthesized antithyroid agent with a proposed less adverse effects profile than other currently used drugs. A simple and rapid reversed phase high performance liquid chromatography assay was developed to determine the concentration of abouthiouzine in human plasma. The procedure involved extraction of the drug and propranolol (internal standard) from the plasma using ethylacetate. The extract was evaporated under nitrogen and the residue was constituted with the mobile phase and injected onto micro-Bondapack phenyl column (10 microm, 3.9 mm x 150 mm). The mobile phase consisted of 10 mM potassium dihydrogen phosphate buffer, acetonitrile, and methanol in the ratio of 60:25:15 (v/v/v, pH=3.0), which was delivered at a rate of 1.5 ml/min. Abouthiouzine and the internal standard were monitored using UV detection at 240 nm; the run time was less than 5 min. The detection limit of abouthiouzine is 0.5 microg/ml. The within- and between-day coefficients of variation were less than 7%. Our method has been successfully used to measure abouthiouzine plasma concentrations in a rabbit model following an intravenous administration of the drug.  相似文献   
3.
Molecular techniques, such as cDNA microarrays, are being used to aid in the elucidation of the mechanisms of toxicity of a variety of compounds. In this study, we evaluate the molecular effects of furan in the rat liver. Sprague-Dawley rats were exposed to 4 or 40 mg/kg furan for up to 14 days. Furan induced an initial degenerative and necrotic phenotype that was followed by inflammation and fibrosis, consistent with previous observations for this compound. RNA was harvested from each lobe of the liver at several time points to observe whether lobe-specific gene expression effects occurred. Similar gene expression changes were observed in all lobes, however the magnitude of gene expression change was more pronounced in the right lobe. Finally, to help determine the correlation between gene expression changes and liver pathology, we applied traditional microarray visualization tools to the assessment of clinical chemistry and pathology parameters.  相似文献   
4.
There are few studies on rhinitis and sick building syndrome (SBS) among students in tropical countries. We studied associations between levels of five fungal DNA sequences, two mycotoxins (sterigmatocystin and verrucarol) and cat allergen (Fel d 1) levels in schools and rhinitis and other weekly SBS symptoms in the students. Fungal DNA was measured by quantitative PCR and cat allergen by ELISA. Pupils (N = 462) from eight randomly selected schools in Johor Bahru, Malaysia participated (96%). Dust samples were collected by cotton swabs and Petri dishes exposed for one week. None of the schools had a mechanical ventilation system, but all classrooms had openable windows that were kept open during lectures and indoor CO2 levels were low (mean 492 ppm; range 380–690 ppm). Weekly nasal symptoms (rhinitis) (18.8%), ocular (11.6%), throat (11.1%), dermal symptoms, headache (20.6%) and tiredness (22.1%) were common. Total fungal DNA in swab samples was associated with rhinitis (p = 0.02), ocular symptoms (p = 0.009) and tiredness (p = 0.001). There were positive associations between Aspergillus versicolor DNA in Petri dish samples, ocular symptoms (p = 0.02) and tiredness (p = 0.001). The level of the mycotoxin verrucarol (produced by Stachybotrys chartarum) in swab samples was positively associated with tiredness (p = 0.04). Streptomyces DNA in swab samples (p = 0.03) and Petri dish samples (p = 0.03) were negatively associated with tiredness. In conclusion, total fungal contamination, measured as total fungal DNA) in the classrooms, Aspergillus versicolor and verrucarol can be risk factors for rhinitis and SBS symptoms among students in the tropical country Malaysia.  相似文献   
5.
Active immunization of Merino and crossbred ewe lambs early in life with a partly purified inhibin derived from bovine follicular fluid (bFF) advanced their puberty. This occurred whether the lambs were immunized from 3 weeks of age or from 9 weeks of age or just 3 times between 3 and 9 weeks. However, the effect was more obvious with multiple injections starting at 3 weeks of age. The ovulation rate of the immunized lambs was significantly higher than that of the control ewes. When lambs were subjected to multiple immunizations the increased ovulation rate persisted in Merinos for at least 1 year after immunization ceased. The lambs injected 3 times only (at 3, 6 and 9 weeks of age) did not show any increase in ovulation rate. Plasma concentrations of FSH and LH measured in blood samples taken 1 week after immunization were not significantly different between the treatment groups. Daily sperm output in the urine and testis diameter were measured in ram lambs from the same breeds and flocks as the ewe lambs. Immunization with the inhibin preparation from 3 weeks of age resulted in a significant increase in daily sperm output (4255 +/- 701 vs 2344 +/- 344 x 10(6), P less than 0.01) and testis diameter (5.21 +/- 0.3 vs 4.33 +/- 0.2 cm, P less than 0.05) in Merino rams examined in the non-breeding season when the rams were aged 23 months. Although the same trend was seen in the following year the differences were not significant. Immunization from 9 weeks of age had no effect. A similar increase in daily sperm output was seen (at 20 and 25 months of age) in crossbred rams immunized from 3 weeks of age but the difference was not significant. Plasma concentrations of FSH (but not LH) in samples from rams immunized from 3 weeks of age were significantly higher than those of control rams at 7 and 60 weeks of age in Merino rams and at 23 and 31 weeks of age in crossbred rams. Plasma FSH concentrations at 21 and 26 weeks of age in the Merino rams immunized from 3 weeks of age were higher than those of control lambs, and these increases preceded a significant (P less than 0.05) increase in testicular diameter at 30 weeks of age (4.99 +/- 0.2 vs 4.37 +/- 0.2 cm). These results suggest that active immunization early in life with an inhibin-enriched fraction from bFF advances puberty in ewe lambs.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
6.
7.
Biotechnology Letters - The degradation activity of two bacteriophages UPMK_1 and UPMK_2 against methicillin-resistant Staphylococcus aureus phages were examined using gel...  相似文献   
8.
9.
Molecular Biology Reports - Lantana camara is an important medicinal plant that contains many active compounds, including pentacyclic triterpenoids, with numerous biological activities. The present...  相似文献   
10.
Anti-miRs are oligonucleotide inhibitors complementary to miRNAs that have been used extensively as tools to gain understanding of specific miRNA functions and as potential therapeutics. We showed previously that peptide nucleic acid (PNA) anti-miRs containing a few attached Lys residues were potent miRNA inhibitors. Using miR-122 as an example, we report here the PNA sequence and attached amino acid requirements for efficient miRNA targeting and show that anti-miR activity is enhanced substantially by the presence of a terminal-free thiol group, such as a Cys residue, primarily due to better cellular uptake. We show that anti-miR activity of a Cys-containing PNA is achieved by cell uptake through both clathrin-dependent and independent routes. With the aid of two PNA analogues having intrinsic fluorescence, thiazole orange (TO)-PNA and [bis-o-(aminoethoxy)phenyl]pyrrolocytosine (BoPhpC)-PNA, we explored the subcellular localization of PNA anti-miRs and our data suggest that anti-miR targeting of miR-122 may take place in or associated with endosomal compartments. Our findings are valuable for further design of PNAs and other oligonucleotides as potent anti-miR agents.  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