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   44篇
  免费   2篇
  国内免费   3篇
化学   39篇
晶体学   1篇
综合类   1篇
物理学   8篇
  2023年   1篇
  2022年   4篇
  2021年   4篇
  2020年   1篇
  2019年   1篇
  2017年   1篇
  2016年   1篇
  2014年   2篇
  2012年   4篇
  2011年   2篇
  2010年   1篇
  2009年   3篇
  2008年   5篇
  2007年   7篇
  2006年   1篇
  2005年   2篇
  2004年   1篇
  2003年   2篇
  2000年   2篇
  1999年   2篇
  1995年   1篇
  1992年   1篇
排序方式: 共有49条查询结果,搜索用时 984 毫秒
31.
超临界CO2流体提取车前子总黄酮的工艺优化   总被引:1,自引:1,他引:0  
通过正交实验研究,对超临界CO2流体提取车前子中黄酮类化合物的工艺进行了优化,实验结果表明各因素对总黄酮提取率的影响程度由小到大依次为:提取温度、夹带剂用量、提取压力、提取次数.在提取时间为0.5 h的条件下,最佳提取工艺条件为:提取温度45 ℃、压力300 Bar、夹带剂无水乙醇用量2.5 mL/g原料、提取2次.  相似文献   
32.
A rapid and sensitive liquid chromatography tandem mass spectrometry (LC–MS/MS) method was developed and validated for the simultaneous determination of two baccharane glycosides (hosenkoside A and hosenkoside K) of total saponins of Semen Impatientis in rat plasma using mogroside V as the internal standard (IS). The analytes were separated using a C18 RP Agilent XDB column (1.8 μm, 50 × 2.1 mm i.d.) and detection of the compounds was done using a TSQ Quantum triple quadrupole mass spectrometer coupled with a negative electrospray ionization source under selection reaction monitoring mode. According to the US Food and Drug Administration guidelines, the established method was fully validated and the results were proved within acceptable limits. The lower limits of quantification of both analytes were 5 ng/mL. The validated method was successfully applied to a pharmacokinetic study of orally administered the total saponins of Semen Impatientis in rats.  相似文献   
33.
ICP-AES法测定新疆鹰嘴豆粉中5种微量元素   总被引:3,自引:0,他引:3  
本文采用ICP-AES法测定了新疆鹰嘴豆粉中铁、铜、锌锰、锶等5种微量元素,并对所含微量元素及其效用进行了初探。结果证明,新疆鹰嘴豆粉的保健功效与其所含的微量元素有一定关联。  相似文献   
34.
FAAS法测定苦杏仁和甜杏仁中的13种金属元素   总被引:1,自引:0,他引:1  
采用硝酸、高氯酸(V/V=4/1)常压微沸条件下消解苦杏仁和甜杏仁样品,火焰原子吸收法测定苦杏仁和甜杏仁中的金属元素:Mn、Ca、K、Mg、Na、Zn、Cu、Fe、Co、Cd、Ni、Pb、Cr的含量,研究了测定不同元素仪器的最佳工作条件、方法的准确度和精密度.结果表明:苦杏仁中Mn、Ca、K、Mg、Na、Zn、Cu、Fe、Co、Cd、Ni和Pb的含量分别为11.756,1614.167,5153.191,238.478,97.668,274.836,16.844,546.316,9.952,3.474,5.979,2.143μg·g-1Cr未检出,方法回收率(n=9)在97.32%-102.57%之间,RSD(n=9)在0.14%-2.22%之间;甜杏仁中Mn、Ca、K、Mg、Ni、Zn、Cu、Fe、Co、Cd、Ni和Pb的含量分别为6.622,1937.503,8663.824,216.956,257.546,77.961,12.483,372.183,7.990,3.666,2.268,3.214μg·g-1Cr未检出,方法回收率(n=9)在97.23%-102.43%之间,RSD(n=9)在0.47%-2.14%之间.该法快速,简单,准确度和精密度均较高,能达到分析要求.  相似文献   
35.
中药胡芦巴磷脂成分的X射—线荧光光谱法直接测定   总被引:1,自引:0,他引:1  
许益民  毛惠新 《分析化学》1992,20(2):219-222
本文首次采用X-射线荧光光谱法直接分析了中药胡芦巴总磷脂成分含量及磷脂组分的分布。该法具有操作简便、快速、准确度高、精密度好、检出限低和样品用量少等优点。本法将是适用于补益中药活性成分磷脂分析的新方法。  相似文献   
36.
提出了用近红外光谱技术快速测定川藏道地药材菥蓂子中指标成分黑芥子苷含量的方法。对黑芥子苷含量在1.962%~3.917%范围的不同来源的菥蓂子,根据其在12 500~3 600 cm-1的近红外吸收光谱,采用偏最小二乘法(PLS)建立了校正模型,比较了光谱不同预处理方法对校正结果的影响。当采用最大最小归一化法时能最有效地提取光谱的信息,此时校正集相关系数(r)为0.989 8,校正集标准偏差(SEC)为0.023 3, 预测集标准偏差(SPE)为0.111 2。该方法快速简便,适合于重要指标成分的快速分析。  相似文献   
37.
To evaluate the detoxification effect of a combination of Radix Glycyrrhizae (GU) and Semen Strychni (SN) from toxicokinetics and drug tissue distribution perspectives, decoctions of processed SN and codecoction of SN and GU (SGN) were prepared, and an HPLC-ESI-MS/MS method was developed to monitor the severe exposure level in 1-month toxicokinetics and tissue distribution experiments to detect brucine and strychnine in rats. The toxicokinetic characteristics and tissue distribution before and after the addition of GU were analyzed. The method was successfully applied to evaluate the toxicokinetics and tissue distribution before and after the combination of SN and GU. The results show that GU decreased the blood concentration of toxic components in SN, and a double peak was observed in the drug time curve. The results of tissue distribution show that a combination of GU and SN significantly decreased the accumulation of toxic substances in metabolic organs and accelerated the clearance of toxic substances in the brain. These results provide a reference for the toxicity reduction mechanism of GU combined with SN.  相似文献   
38.
采用高效液相色谱/电喷雾飞行时间质谱联用技术(HPLC/ESI-TOF/MS),研究4种七叶皂苷的分子结构与裂解规律间的关系,并对娑罗子中的七叶皂苷类化合物进行鉴定。实验采用反相C18色谱柱,以乙腈-0.2%乙酸溶液为流动相,二元线性梯度洗脱,通过与电喷雾飞行时间质谱联用获得娑罗子中各皂苷成分的精确分子量和分子式;采用质谱碰撞诱导解离技术获得各化合物碎片裂解信息,结合文献对娑罗子中的14种皂苷类化合物进行了初步鉴定。研究表明,高效液相色谱-电喷雾飞行时间质谱联用技术是娑罗子中皂苷类化合物鉴别的有效工具。  相似文献   
39.
In the past decade, mRNA markers have been well demonstrated as promising molecular markers in forensic body fluid identification (BFI), and successfully used in wide applications. Several studies have assessed the performance of semen-specific mRNA markers in distinguishing semen from other common body fluids at the crime scene. Infertility has been reported as a global health problem that is affecting approximately 15% of couples worldwide. Therefore, it is important for forensic researchers to consider the impact of infertility on semen identification. This study aimed to explore the effect of semen from infertile men (hereinafter “infertile semen”) on BFI and to identify semen-specific mRNAs that can efficiently and accurately distinguish normal and infertile semen samples from other body fluids. Results showed that the selected five mRNAs (KLK3, TGM4, SEMG1, PRM1, and PRM2) performed a significantly high semen specificity in normal semen. Moreover, KLK3 was slightly influenced by infertile semen samples with over 98% positive results in all semen samples. The accuracy to predict normal semen reached up to 96.6% using the discrimination function Y1 with KLK3 and PRM1. However, when the infertile semen samples were included in discrimination function (function Y2 with KLK3), the accuracy rate of semen identification (including the normal and infertile semen) was down to 89.5%. Besides, the sensitivity of multiplex assay could reach down to 50pg. Our results suggest that it is important to consider the presence of infertile semen when using mRNAs to identify semen samples, which would have a far-reaching impact in forensic identification.  相似文献   
40.
正常与不育男性精浆锌和铜的研究   总被引:1,自引:1,他引:1  
测定了正常男性33例与不育男性144例糖浆微量元素锌和铜的含量(μg/mL):正常组锌202.59±52.9,铜0.25±0.019,不育组锌117±57.5,铜0.48±0.38.所得结果表明:不育组精浆锌明显低于正常组,差别有极显著意义.不育组精浆铜明显高于正常组,差别有显著意义.  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