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   96篇
  免费   3篇
电工技术   2篇
化学工业   11篇
机械仪表   1篇
建筑科学   3篇
能源动力   1篇
轻工业   8篇
水利工程   6篇
石油天然气   15篇
无线电   5篇
一般工业技术   10篇
冶金工业   26篇
自动化技术   11篇
  2022年   1篇
  2020年   4篇
  2019年   2篇
  2018年   2篇
  2017年   1篇
  2016年   3篇
  2015年   2篇
  2014年   4篇
  2013年   7篇
  2012年   2篇
  2011年   7篇
  2010年   4篇
  2009年   2篇
  2008年   2篇
  2007年   1篇
  2004年   1篇
  2003年   3篇
  2002年   2篇
  2000年   1篇
  1999年   1篇
  1998年   5篇
  1997年   7篇
  1996年   4篇
  1995年   4篇
  1994年   2篇
  1993年   2篇
  1985年   1篇
  1984年   3篇
  1977年   2篇
  1976年   4篇
  1974年   1篇
  1973年   1篇
  1972年   2篇
  1971年   1篇
  1970年   4篇
  1969年   2篇
  1967年   2篇
排序方式: 共有99条查询结果,搜索用时 15 毫秒
91.
J001X, an acylated poly-(1,3)-galactoside isolated from Klebsiella pneumoniae proteoglycan, has been developed to target cells from the monocyte-macrophage lineage. Recent experimental work and initial clinical trials have proved the potential of this molecule labeled with 99mTc for the scintigraphy of inflammatory foci. In a model of radiation-induced inflammation in pigs, the scintigraphic contrast was observed to be very sensitive to a single injection of methylprednisolone given 12 h before scintigraphy. The present study was undertaken to confirm this effect and to estimate the possible interference of various anti-inflammatory agents on the in vivo targeting of macrophages by J001X. Methylprednisolone, dexamethasone, indomethacin and methotrexate used at an immunosuppressive dose were tested to assess the possible risk of false-negative examinations in patients thus treated. Analysis of the results indicated that among the four drugs tested, only methylprednisolone at 0.5-1 mg/kg could interfere with J001X scintigraphy.  相似文献   
92.
Development of a new method for the determination of Cr(III) and Cr(VI) is described. Anion-exchange high-performance liquid chromatography (HPLC) was used to separate Cr(III) and Cr(VI) with on-line detection by inductively coupled plasma atomic emission spectroscopy (ICP-AES) at 2766 A in preliminary studies, and inductively coupled plasma mass spectrometry (ICP-MS) with single-ion monitoring at m/z 52 and m/z 53 for final work. A mobile phase consisting of ammonium sulfate and ammonium hydroxide was used, and a simple chelation procedure with EDTA was followed to stabilize the Cr(III) species in standard solutions. ICP-MS results indicated the feasibility of using chromium isotope m/z 53 instead of the more abundant m/z 52 isotope due to a high mobile-phase background most significantly from the SO+ polyatomic interference. The absolute detection limits based on peak-height calculations were 40 pg for Cr(III) and 100 pg for Cr(VI) in aqueous media by HPLC-ICP-MS. The linear dynamic range extended from 5 ppb (ng/ml) to 1 ppm (micrograms/ml) for both species. By HPLC-ICP-AES, detection limits were 100 ng for Cr(III) and 200 ng for Cr(VI). Cr(III) was detected in NIST-SRM 1643c (National Institute of Standards and Technology-Standard Reference Material, Trace Elements in Water) by HPLC-ICP-MS at the 20 ppb level.  相似文献   
93.
A newborn with transposition of the great arteries presented with rupture of the ductus arteriosus after balloon catheter atrioseptostomy. The necropsy study demonstrated persistent ductus patency, and a 0.5-cm-long horizontal fissure could be observed. On microscopy, there was laceration of the intimal layer, with wall dissection and focal hemorrhage extending to the adventitia. Ductus rupture was attributed to the wall weakness, as a consequence of prostaglandin E1 administration.  相似文献   
94.
Most airlines refuse to board passengers known or believed to have contagious diseases. Such rigor can scarcely be justified by reference to either laws or regulations. It introduces the risk of arbitrary, mistaken, or prejudiced conduct in areas in which international organizations recommend the greatest liberalization, and it can cause serious harm to certain patients. Finally, it does not seem logical, for airlines learn about only a small fraction of the contagious persons who travel, and public health is much more greatly endangered by unknown contagious persons. Normal hygienic conditions aboard planes suppress the risks of contagion concerning most diseases transmitted by insects or through contact with the skin, with mucuous membranes, with the faeces, or with urine. Airlines should continue to refuse to transport only those passengers having diseases which are characterized by vomiting or serious diarrhoea or which are transmitted through the air if it is impossible by simple means to avoid the risk of contaminating other travellers and any members of the flight crew who might be receptive.  相似文献   
95.
A laboratory investigation was carried out to study live-line washing of insulators, with special attention to the two washing procedures which adopt: hand-held jet nozzles; and helicopter mounted nozzles. The aspects related to safety and those related to efficiency and reliability were considered. On the basis of the results, safe working distances and indications to define optimal washing procedures were derived  相似文献   
96.
The assessment of the efficacy of skin improvement treatments could be obtained by several different instrumental tests. In parallel to these techniques, a visual evaluation more closely related to the consumer's considerations would be of value for the assessment of slimming treatments efficacy. A method of macrorelief scoring of skin has been developed as an alternative to usual clinical assessment. It consisted of acquiring macroscopic views of the most representative areas of women's cellulite. Photographs were taken after application of a gripping system around the thigh, used to increase the orange peel look of the skin over a restricted area (200 cm(2)) and then classified by observers according to reference groups of cellulite intensity. This publication presents the validation of this photograding method and the results of the first 2-month double-blind placebo-controlled clinical study performed on 30 subjects with this technique associated with: (i) B mode ultrasound imaging in order to correlate scorings with instrumental measurements of thigh adipose tissue thickness variations and (ii) self-evaluation questionnaire aiming at evaluating the overall appraisal and attitude towards the two products. The results clearly showed that the effects of 'slimming products' on the skin's macrorelief improvement could be evaluated objectively using this photograding technique. Moreover, the method described here allows delayed scoring of cellulite intensity from a restricted examination area independent of whole-subject appearance, thus decreasing subjectivity.  相似文献   
97.
We describe here an efficient and regioselective synthesis of arylselanyl anilines by copper‐catalyzed direct arylselenation of arylamines. Using a catalytic amount of copper iodide in dimethyl sulfoxide at 110 °C under an air atmosphere, a range of arylselanyl anilines was obtained directly from substituted diaryl diselenides in moderate to good yields via C H bond cleavage of aryl amines.

  相似文献   

98.
Cyanide, a hazardous substance, is released into the environment as a result of natural processes of various industrial activities which is a toxic pollutant according to Environmental Protection Agency. In nature, some microorganisms are responsible for the degradation of cyanide, but there is only limited information about the degradation characteristics of Basidiomycetes for cyanide. The aim of the present study is to determine cyanide degradation characteristics in some Basidiomycetes strains including Polyporus arcularius (T 438), Schizophyllum commune (T 701), Clavariadelphus truncatus (T 192), Pleurotus eryngii (M 102), Ganoderma applanatum (M 105), Trametes versicolor (D 22), Cerrena unicolor (D 30), Schizophyllum commune (D 35) and Ganoderma lucidum (D 33). The cyanide degradation activities of P. arcularius S. commune and G. lucidum were found to be more than that of the other fungi examined. The parameters including incubation time, amount of biomass, initial cyanide concentration, temperature, pH and agitation rate were optimized for the selected three potential fungal strains. The maximum cyanide degradation was obtained after 48 h of incubation at 30 °C by P. arcularius (T 438). The optimum pH and agitation rate were measured as 10.5 and 150 rev/min, respectively. The amount of biomass was found as 3.0 g for the maximum cyanide biodegradation with an initial cyanide concentration of 100 mg/L. In this study, agar was chosen entrapment agent for the immobilization of effective biomass. We suggested that P. arcularius (T 438) could be effective in the treatment of contaminated sites with cyanide due to capability of degrading cyanide.  相似文献   
99.
Dinoflagellates bioluminescence mechanism depends upon a luciferin–luciferase reaction that promotes blue light emission (480 nm) in specialized luminogenic organelles called scintillons. The scintillons contain luciferin, luciferase and, in some cases, a luciferin-binding protein (LBP), which prevents luciferin from non-enzymatic oxidation in vivo. Even though dinoflagellate bioluminescence has been studied since the 1950s, there is still a lack of mechanistic understanding on whether the light emission process involves a peroxidic intermediate or not. Still, bioassays employing luminous dinoflagellates, usually from Gonyaulax or Pyrocystis genus, can be used to assess the toxicity of metals or organic compounds. In these dinoflagellates, the response to toxicity is observed as a change in luminescence, which is linked to cellular respiration. As a result, these changes can be used to calculate a percentage of light inhibition that correlates directly with toxicity. This current approach, which lies in between fast bacterial assays and more complex toxicity tests involving vertebrates and invertebrates, can provide a valuable tool for detecting certain pollutants, e.g., metals, in marine sediment and seawater. Thus, the present review focuses on how the dinoflagellates bioluminescence can be applied to evaluate the risks caused by contaminants in the marine environment.  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