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   51篇
  免费   2篇
化学工业   6篇
金属工艺   1篇
轻工业   9篇
无线电   4篇
一般工业技术   2篇
冶金工业   26篇
自动化技术   5篇
  2022年   1篇
  2019年   1篇
  2018年   1篇
  2016年   1篇
  2015年   2篇
  2014年   1篇
  2013年   2篇
  2011年   3篇
  2010年   1篇
  2009年   3篇
  2008年   1篇
  2006年   1篇
  2005年   1篇
  2004年   1篇
  2003年   2篇
  2002年   1篇
  2001年   1篇
  1998年   12篇
  1997年   5篇
  1996年   3篇
  1995年   3篇
  1993年   2篇
  1991年   1篇
  1983年   1篇
  1976年   1篇
  1974年   1篇
排序方式: 共有53条查询结果,搜索用时 615 毫秒
41.
Many applications of object recognition in the presence of pose uncertainty rely on statistical models-conditioned on pose-for observations. The image statistics of three-dimensional (3-D) objects are often assumed to belong to a family of distributions with unknown model parameters that vary with one or more continuous-valued pose parameters. Many methods for statistical model assessment, for example the tests of Kolmogorov-Smirnov and K. Pearson, require that all model parameters be fully specified or that sample sizes be large. Assessing pose-dependent models from a finite number of observations over a variety of poses can violate these requirements. However, a large number of small samples, corresponding to unique combinations of object, pose, and pixel location, are often available. We develop methods for model testing which assume a large number of small samples and apply them to the comparison of three models for synthetic aperture radar images of 3-D objects with varying pose. Each model is directly related to the Gaussian distribution and is assessed both in terms of goodness-of-fit and underlying model assumptions, such as independence, known mean, and homoscedasticity. Test results are presented in terms of the functional relationship between a given significance level and the percentage of samples that wold fail a test at that level.  相似文献   
42.
43.
OBJECTIVE: To determine normal serum bone-related biochemical variables in older African-Americans. DESIGN: A convenience sample of older African-Americans who had a health screening and blood testing for calciotropic hormones was compared with white Americans who were recruited at the end of the Systolic Hypertension in the Elderly Program (SHEP) study and were not on a thiazide diuretic. SETTING: Community-dwelling African-Americans who participated in SHEP or who attended one of two mass health screenings. PARTICIPANTS: Thirty-two African-Americans aged 68-93 years and 43 white Americans aged 70-89 years. MEASUREMENTS: Twenty-five hydroxyvitamin D (25OHD), parathyroid hormone, osteocalcin, and calcitonin. RESULTS: Serum 25OHD levels in 38% of the African-American men and 38% of African-American women were less than 8 ng/mL compared with 22% of Caucasian men and 40% of Caucasian women. Serum parathyroid hormone (PTH) was above the normal range in 25% of men and 33% of women of African-American descent and 14% of Caucasian men and 30% of Caucasian women. Serum 25OHD was lower (P < 0.05) in individuals with a previous history of fracture. Serum albumin (P < 0.05), calcitonin (P < 0.05), and osteocalcin (P < 0.05), but not 25OHD, were lower in African-Americans (men and women) when compared with Caucasians (P < 0.05). Serum calcium corrected for albumin was higher in the African-Americans than in the Caucasians (P < 0.05). As previously reported in Caucasians, PTH was inversely related to log 25OHD in African-Americans. Serum osteocalcin was positively correlated to PTH in African-Americans, as previously reported in Caucasians. Log 25OHD correlated inversely with osteocalcin in African-Americans, but this was not seen in Caucasians. CONCLUSIONS: In this limited sample, hypovitaminosis D (as assessed by 25OHD level) with secondary hyperparathyroidism occurred frequently in elderly African-Americans. Osteocalcin, a measure of osteoblast activity, correlated with 25OHD and parathyroid hormone. Osteocalcin serum levels were lower in African-Americans than Caucasians, but serum calcium corrected for albumin was higher in the former compared to the latter.  相似文献   
44.
Fatty acid analyses were carried out on phosphoglycerides isolated from microsomal fractions of the rectal gland of the dogfish,Scyliorthinus canicula, and gills of the cod,Gadus morhua. Ratios of (n−3)/(n−6) polyunsaturated fatty acids were ca. 10 for phosphatidylcholine, (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS) from cod gills, reflecting high concentrations of 20∶5 (n−3) and 22∶6(n−3). The ratio for phosphatidylinositol (PI) from cod gills was 1.3, reflecting high concentrations of 20∶4(n−6) as well as (n−3) polyunsaturates. PC, PE and PS from rectal glands all had much lower (n−3)/(n−6) ratios than in cod gills, reflecting higher concentrations of 20∶4(n−6), but the lowest ratio was again present in PI. The latter phospholipid had high concentrations of 18∶0 in both tissues. The relative constancy of the fatty acid composition of PI in the two salt-secreting tissues and its similarity to mammalian phospholipids is considered to reflect its specialized role in biomembranes.  相似文献   
45.
46.
This was a preliminary study to investigate whether hyaline cartilage could be easily identified in mechanically recovered meat (MRM) and whether its presence could be used as a possible marker for MRM in meat products. MRMs produced from beef, pork, lamb, chicken and turkey, using a variety of machine types and processing conditions, were compared to both minced and colloid milled hand-deboned samples, using a chemical staining technique followed by examination using the light microscope. The methodology was tested on various mixtures of MRM and hand-deboned meat. Although this technique, as with most microscopy techniques generally, is not suitable for quantitative determinations, the results indicate that light microscopy could be used as a useful screening method.  相似文献   
47.
48.
6-Anilino-5,8-quinolinedione (LY83583) has been widely used as an agent to reduce levels of nitric oxide (NO)-dependent cGMP in tissues. We report here that suppression of NO formation and production of superoxide during enzymatic reduction of LY83583 by neuronal NO synthase appeared to be potentially involved in the pharmacological action caused by LY83583. LY83583 suppressed neuronal NO synthase activity of 20,000 x g rat cerebellar supernatant preparation in a concentration-dependent manner (IC50 value = 12.9 microM). A kinetic study revealed that LY83583 is a competitive inhibitor with respect to NADPH, with a Ki value of 2.57 microM. With purified neuronal NO synthase it was found that LY83583 was a potent inhibitor of NO formation by the enzyme and served as efficient substrate for reduction with a specific activity of 173 nmol of NADPH oxidized per mg of protein per minute. The reductase activity was stimulated about 19.8-fold by addition of CaCl2/calmodulin, indicating that the presence of CaCl2/calmodulin is essential to express maximal activity of LY83583 reduction. Although LY83583 was a good substrate for both NADPH-cytochrome P450 reductase (P450 reductase) and DT-diaphorase, these flavin enzymes-catalyzed reductions of LY83583 were less than the neuronal NO synthase-mediated reduction in the presence of CaCl2/calmodulin. Enzymatic generation of superoxide during reduction of LY83583 by neuronal NO synthase, P450 reductase or DT-diaphorase was confirmed by electron spin resonance (ESR) experiments. Thus the present results indicate that a benzoquinone derivative LY83583 appears to interact with the P450 reductase domain on neuronal NO synthase, resulting in inhibition of NO formation and superoxide generation, which is involved in suppression of intracellular cGMP content.  相似文献   
49.
Little is known about the self care employed by Irish doctors, though studies in other countries suggest this is likely to be less than ideal. In this study 76 doctors; general practitioner trainees, general practitioners and hospital consultants, completed a questionnaire on their self management of illness. High levels of self-prescribing and referral were discovered. The implications for the health of doctors in Ireland and the need for an occupational health service for doctors are discussed.  相似文献   
50.
The way in which breeding families of laboratory-born marmosets used the space provided by their cages, and a small protruding 'veranda', was assessed in order to determine the popularity of the veranda as a form of environmental enrichment, and the extent to which the marmosets confined themselves to only part of the cage. The veranda was found to be of enduring interest to the marmosets whose occupancy of this space was an order of magnitude greater than the rest of the cage. The upper part of the cage was preferred to the bottom half. This preference was greater in larger cages and decreased when larger cages were temporarily reduced in size. It is unlikely, however, that the distribution of the occupancy of different parts of the cage resulted primarily from a fear of people in the holding room. The veranda, which was the most preferred place in the cage, was the nearest part of the cage to people in the room. Occupancy of the lower part of the cage increased when human observers sat on the floor, suggesting that some of the marmosets' behaviour comprised approaching, rather than avoiding, the observers, possibly for reasons of curiosity and social interaction.  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