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   187篇
  免费   3篇
电工技术   2篇
化学工业   33篇
金属工艺   1篇
建筑科学   5篇
能源动力   2篇
轻工业   25篇
水利工程   1篇
石油天然气   2篇
无线电   21篇
一般工业技术   22篇
冶金工业   50篇
原子能技术   5篇
自动化技术   21篇
  2021年   3篇
  2020年   3篇
  2019年   2篇
  2017年   4篇
  2016年   4篇
  2014年   5篇
  2013年   6篇
  2012年   3篇
  2011年   3篇
  2010年   6篇
  2009年   6篇
  2008年   3篇
  2007年   5篇
  2006年   9篇
  2005年   7篇
  2004年   3篇
  2003年   3篇
  2002年   4篇
  2001年   8篇
  2000年   4篇
  1999年   3篇
  1998年   15篇
  1997年   17篇
  1996年   4篇
  1995年   7篇
  1994年   2篇
  1993年   4篇
  1992年   3篇
  1991年   2篇
  1989年   1篇
  1988年   2篇
  1986年   2篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1978年   2篇
  1976年   5篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1970年   2篇
  1966年   1篇
  1964年   6篇
  1963年   2篇
  1962年   4篇
  1961年   1篇
  1960年   2篇
  1959年   1篇
  1958年   1篇
  1957年   1篇
排序方式: 共有190条查询结果,搜索用时 0 毫秒
181.
Fundoplication is the most widely used antireflux method, whereas Roux-en-Y duodenal diversion (partial gastrectomy, vagotomy, and Roux-en-Y reconstruction) has been used in fewer patients with more complicated gastroesophageal reflux disease. Abnormal esophageal pH values are normalized after successful fundoplication. However, very little is known about possible changes in the pH profile after successful Roux-en-Y duodenal diversion. A total of 37 patients with severe gastroesophageal reflux disease were treated by fundoplication (n=22) or Roux-en-Y duodenal diversion (n=15). Postoperatively all patients in both groups were symptom free and healing of esophagitis was verified endoscopically. After fundoplication, the 24-hour esophageal acid exposure decreased significantly (P=0.03) and the pH profile normalized (pH<4 in 5.8%+/-2.4% of the recorded time). However, the decrease in esophageal acid exposure was not significant (P=0.77) after successful Roux-en-Y reconstruction and the pH profile remained abnormal (pH<4 in 15.1%+/-4.3%). It was concluded that 24-hour esophageal pH monitoring is a reliable means of assessing the results of fundoplication, but the current test criteria should be reexamined in evaluating the results of Roux-en-Y duodenal diversion. Healing of esophagitis after Roux-en-Y duodenal diversion despite abnormal acid reflux, as shown by 24-hour pH measurements, suggests that duodenal contents also have a role in the pathogenesis of esophagitis in an acid milieu.  相似文献   
182.
Neuropathic arthropathy is a severe chronic degenerative condition associated with decreased or absent sensory innervation of the involved joint. Existing animal models of neuropathic arthritis are limited by the technical difficulties of obtaining either highly selective or complete joint denervation in a minimally invasive fashion. We undertook experiments to determine the feasibility of using the newly described method of selective neuronal lesioning with injected immunotoxin as a means of creating a more tractable model of neuropathic arthritis. Retrograde tracing with fluorochrome revealed that the knee joint of the female Wistar rat is supplied by 581 +/- 31 (mean +/- SD) joint afferents. Immunohistochemistry confirmed that virtually all sensory neurons in the rat express the cell surface receptor Thy 1. Injection of rat knee joints with an immunotoxin targeted toward Thy 1 resulted in the selective ablation of an average of 88% of the joint afferents identified with fluorochrome that are normally found in the ipsilateral L3 and L4 ganglia.  相似文献   
183.
184.
185.
Six families were studied which included 11 members with dermatitis herpetiformis (DH) and three with coeliac disease (CD). Proximal jejunal biopsies performed on 20 relatives revealed villous atrophy in eight. Of these eight, two, both siblings of patients with DH, had a history of juvenile CD. Determinations of histocampatibility (HLA) antigens showed that HLS-B8 occurred in all six families although two patients with DH and one relative with a history of juvenile CD lacked this antigen. In one family the haplotype A1,B8 was associated with DH, villous atrophy, juvenile diabetes and Addison's disease. Skin biopsy failed to reveal IgA in any of the 44 relatives studied for this immunoglobulin. Antireticulin antibody was detected in the sera of seven (17%) relatives.  相似文献   
186.
Journal of the American Oil Chemists' Society - The enolate anions from isopropylidene protected monoacylglycerols have been successfully alkylated with alkyl iodides of various chain length....  相似文献   
187.
The feasibility of ultra-thin-layer chromatography (UTLC) and atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry (AP-MALDI-MS) for bioanalysis was studied with benzodiazepines as model substances in human urine. Two-dimensional (2D) UTLC was shown to be an efficient technique for the separation of benzodiazepines. Separations occurred in 4-12 min, and the separated compounds were identified by AP-MALDI-MS. The limits of detection with AP-MALDI-MS and AP-MALDI-MS/MS were in the picomole range and thus low enough for bioanalysis. The applicability of the 2D UTLC-AP-MALDI-MS was demonstrated in detection of metabolites with an authentic biological urine sample.  相似文献   
188.
Nilsson  Anne  Radeborg  Karl  Salo  Ilkka  Björck  Inger 《Nutrition journal》2012,11(1):1-9

Background

One of the major challenges associated with our ageing population is the increasing incidence of age-associated cognitive decline, which has significant implications for an individual's ability to lead a productive and fulfilling life. In pure economic terms the costs of ageing reflects decreased productivity and engagement with the workforce. The maintenance of brain health underpinning intact cognition is a key factor to maintaining a positive, engaged, and productive lifestyle. In light of this, the role of diet, including supplementation with nutritional and even pharmacological interventions capable of ameliorating the neurocognitive changes that occur with age constitute vital areas of research.

Methods

In order to reduce cognitive ageing, the ARC longevity intervention (ARCLI) was developed to examine the effects of two promising natural pharmacologically active supplements on cognitive performance. ARCLI is a randomized, placebo-controlled, double-blind, 3-arm clinical trial in which 465 participants will be randomized to receive an extract of Bacopa monnieri (CDRI08 300 mg/day), Pycnogenol (150 mg/day), or placebo daily for 12 months. Participants will be tested at baseline and then at 3, 6 and 12 months post-randomization on a wide battery of cognitive, neuropsychological and mood measures, cardiovascular (brachial and aortic systolic and diastolic blood pressures as well as arterial stiffness), biochemical (assays to measure inflammation, oxidative stress and safety) as well as genetic assessments (telomere length and several Single Nucleotide Polymorphisms). The primary aim is to investigate the effects of these supplements on cognitive performance. The secondary aims are to explore the time-course of cognitive enhancement as well as potential cardiovascular and biochemical mechanisms underpinning cognitive enhancement over the 12 months of administration. ARCLI will represent one of the largest and most comprehensive experimental clinical trials in which supplements are administered to elderly participants. Results from ARCLI may help develop novel preventative health practices and nutritional/pharmacological targets in the elderly for cognitive and brain health.

Trial registration

Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12611000487910  相似文献   
189.
The main objective of this study was to determine the level of surface contamination in fish processing factories and the presence of Listeria in the factory environment and products. Another objective was evaluation of the different hygiene-monitoring methods. Total aerobic heterotrophic and enterobacteria, yeast and mold samples were collected and ATP levels measured in 28 factories. The number of well or adequately washed and disinfected factories was small (2 of 28), in terms of total aerobic heterotrophic bacterial counts on the surfaces. Most surfaces contaminated with bacteria were heavily contaminated. Results of the ATP and the total bacteria contact agar slide methods were poorly correlated (r = 0.21) although 68% of the samples were categorized as good to moderate or unacceptable with both methods. The Listeria-positive surface samples usually contained increased numbers of total bacteria (70.9%). The contamination of products and raw fish together with Listeria spp. was 45% and with Listeria monocytogenes 12%. Cold smoked fish was the most contaminated, with 75% Listeria spp. and cold salted fish with 20% L. monocytogenes. Listeria innocua was found in the samples more than twice as often as L. monocytogenes.  相似文献   
190.
The expected emission spectra (full, Bremsstrahlung, recombination, and line) of neon focussed plasma have been studied for different conditions. Expected neon plasma spectra at certain electron temperature range have been plotted. The suitable electron temperatures ranges for neon plasma soft X-ray emission and extreme ultraviolet emission have been investigated. The X-ray ratio curves for various electron temperatures with probable electron and ion densities of the neon plasma produced have been computed with the assumption of non-local thermodynamic equilibrium model for the distribution of the ionic species. These ratio curves could be used for electron temperatures deduction of neon plasma focus.  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