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   121篇
  免费   5篇
化学   73篇
晶体学   2篇
力学   3篇
数学   1篇
物理学   47篇
  2023年   2篇
  2022年   7篇
  2021年   7篇
  2020年   4篇
  2019年   5篇
  2018年   5篇
  2017年   5篇
  2016年   10篇
  2015年   4篇
  2014年   3篇
  2013年   14篇
  2012年   8篇
  2011年   11篇
  2010年   3篇
  2009年   4篇
  2008年   5篇
  2007年   8篇
  2004年   1篇
  2003年   2篇
  2002年   1篇
  1995年   1篇
  1989年   1篇
  1987年   1篇
  1986年   3篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1979年   1篇
  1971年   1篇
  1969年   2篇
  1968年   3篇
  1967年   1篇
排序方式: 共有126条查询结果,搜索用时 15 毫秒
101.
The recent measurements of differential and total cross sections, the ratio of the integrated and total cross sections and the values of the slope parameter at Collider energy have been simultaneously fitted for the first time by using a pole+cut model.  相似文献   
102.
The dual absorptive model has been used to fit the recently measured experimental data on the differential cross-section, density matrix elements and polarization in the reaction πp→k°(890)Λ.  相似文献   
103.
Under certain conditions, ultrafast pulsed laser interaction with matter leads to the formation of self-organized conical as well as periodic surface structures(commonly reffered to as, laser induced periodic surface structures, LIPSS). The purpose of the present investigations is to explore the effect of fsec laser fluence and ambient environments(Vacuum O_2) on the formation of LIPSS and conical structures on the Ti surface. The surface morphology was investigated by scanning electron microscope(SEM). The ablation threshold with single and multiple(N = 100) shots and the existence of an incubation effect was demonstrated by SEM investigations for both the vacuum and the O_2 environment. The phase analysis and chemical composition of the exposed targets were performed by x-ray diffraction(XRD) and energy dispersive x-ray spectroscopy(EDS), respectively. SEM investigations reveal the formation of LIPSS(nano micro). FFT d-spacing calculations illustrate the dependence of periodicity on the fluence and ambient environment. The periodicity of nano-scale LIPSS is higher in the case of irradiation under vacuum conditions as compared to O_2. Furthermore, the O2 environment reduces the ablation threshold. XRD data reveal that for the O_2 environment, new phases(oxides of Ti) are formed. EDS analysis exhibits that after irradiation under vacuum conditions, the percentage of impurity element(Al) is reduced. The irradiation in the O_2 environment results in 15% atomic diffusion of oxygen.  相似文献   
104.
Tigilanol tiglate (EBC-46) is a small-molecule natural product under development for the treatment of cancers in humans and companion animals. The drug is currently produced by purification from the Australian rainforest tree Fontainea picrosperma (Euphorbiaceae). As part of a selective-breeding program to increase EBC-46 yield from F. picrosperma plantations, we investigated potential gene biomarkers associated with biosynthesis of EBC-46. Initially, we identified individual plants that were either high (>0.039%) or low EBC-46 (<0.008%) producers, then assessed their differentially expressed genes within the leaves and roots of these two groups by quantitative RNA sequencing. Compared to low EBC-46 producers, high-EBC-46-producing plants were found to have 145 upregulated genes and 101 downregulated genes in leaves and 53 upregulated genes and 82 downregulated genes in roots. Most of these genes were functionally associated with defence, transport, and biosynthesis. Genes identified as expressed exclusively in either the high or low EBC-46-producing plants were further validated by quantitative PCR, showing that cytochrome P450 94C1 in leaves and early response dehydration 7.1 and 2-alkenal reductase in roots were consistently and significantly upregulated in high-EBC-46 producers. In summary, this study has identified biomarker genes that may be used in the selective breeding of F. picrosperma.  相似文献   
105.
Cholesterol is essential for normal human health, but elevations in its serum levels have led to the development of various complications, including hypercholesterolemia (HC). Cholesterol accumulation in blood circulation formsplaques on artery walls and worsens the individuals’ health. To overcome this complication, different pharmacological and non-pharmacological approaches are employed to reduce elevated blood cholesterol levels. Atorvastatin and rosuvastatin are the most commonly used drugs, but their prolonged use leads to several acute side effects. In recent decades, the potential benefit of ingesting yogurt on lipid profile has attracted the interest of researchers and medical professionals worldwide. This review aims to give an overview of the current knowledge about HC and the different therapeutic approaches. It also discusses the health benefits of yogurt consumption and highlights the overlooked phyto-enrichment option to enhance the yogurt’s quality. Finally, clinical studies using different phyto-enriched yogurts for HC management are also reviewed. Yogurt has a rich nutritional value, but its processing degrades the content of minerals, vitamins, and other vital constituents with beneficial health effects. The option of enriching yogurt with phytoconstituents has drawn a lot of attention. Different pre-clinical and clinical studies have provided new insights on their benefits on gut microbiota and human health. Thus, the yogurtphyto-enrichment with stanol and β-glucan have opened new paths in functional food industries and found healthy andeffective alternatives for HC all along with conventional treatment approaches.  相似文献   
106.
Saffron is a valued herb, obtained from the stigmas of the C. sativus Linn (Iridaceae), with therapeutic effects. It has been described in pharmacopoeias to be variously acting, including as an anti-depressant, anti-carcinogen, and stimulant agent. The therapeutic effects of saffron are harbored in its bioactive molecules, notably crocins, the subject of this paper. Crocins have been demonstrated to act as a monoamine oxidase type A and B inhibitor. Furthermore, saffron petal extracts have experimentally been shown to impact contractile response in electrical field stimulation. Other research suggests that saffron also inhibits the reuptake of monoamines, exhibits N-methyl-d-aspartate antagonism, and improves brain-derived neurotrophic factor signaling. A host of experimental studies found saffron/crocin to be similarly effective as fluoxetine and imipramine in the treatment of depression disorders. Saffron and crocins propose a natural solution to combat depressive disorders. However, some hurdles, such as stability and delivery, need to be overcome.  相似文献   
107.
Summary A semiquantitative method for the determination of iron, copper, cobalt, nickel and zinc is described which is based on circular thin-layer chromatographic technique. The error is minimized to ± 5% and interference of about 40 metal ions is removed by solvent extraction. The application of the method has been demonstrated by the determination of these metal ions in human blood and tissue and the method is suggested for the study of airborne particulates.
Zusammenfassung Ein halbquantitatives Verfahren zur Bestimmung von Eisen, Kupfer, Kobalt, Nickel und Zink auf dünnschicht-ringchromatographischem Wege wurde beschrieben. Der Fehler wurde auf ±5% eingeschränkt und die störende Wirkung von etwa 40 Metallionen durch Lösungsmittelextraktion beseitigt. Die Anwendbarkeit des Verfahrens für die Bestimmung in menschlichem Blut und Gewebe wurde gezeigt bzw. für die Untersuchung atmosphärischer Verunreinigungen empfohlen.
  相似文献   
108.
Shahida  S.  Abbasi  Y. A.  Ali  A.  Khan  M. I.  Shah  K. H.  Farooq  U.  Hafeez  M. 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(3):1215-1223
Journal of Radioanalytical and Nuclear Chemistry - Solvent extraction of Eu(III) and Nd(III) from aqueous medium was investigated by sulfasalazine in benzoyl alcohol as single extractant and then...  相似文献   
109.
A number of the thieno[3,2‐c][1,8]‐naphthyridin‐4(5H)‐ones are chemoselectively synthesized from 4‐(4′‐aryloxybut‐2′‐ynylthio)‐1‐phenyl‐1,8‐naphthyridin‐2(1H)‐ones in 82–90% yield by the formation of sulfoxide, followed by [2,3] and [3,3]sigmatropic rearrangement and an intramolecular Michael addition. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:87–92, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20234  相似文献   
110.
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