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   191篇
  免费   1篇
化学工业   19篇
金属工艺   2篇
机械仪表   2篇
建筑科学   16篇
矿业工程   2篇
能源动力   2篇
轻工业   20篇
水利工程   6篇
无线电   14篇
一般工业技术   18篇
冶金工业   75篇
自动化技术   16篇
  2022年   1篇
  2021年   3篇
  2020年   3篇
  2019年   3篇
  2018年   3篇
  2017年   3篇
  2016年   3篇
  2015年   3篇
  2014年   2篇
  2013年   7篇
  2012年   7篇
  2011年   6篇
  2010年   6篇
  2009年   4篇
  2008年   4篇
  2007年   4篇
  2006年   5篇
  2005年   3篇
  2004年   4篇
  2003年   5篇
  2002年   3篇
  2001年   6篇
  2000年   4篇
  1999年   4篇
  1998年   23篇
  1997年   14篇
  1996年   10篇
  1995年   7篇
  1994年   5篇
  1993年   3篇
  1992年   2篇
  1991年   6篇
  1990年   3篇
  1989年   5篇
  1988年   2篇
  1985年   2篇
  1984年   3篇
  1983年   5篇
  1982年   1篇
  1981年   1篇
  1978年   1篇
  1973年   1篇
  1964年   1篇
  1925年   1篇
排序方式: 共有192条查询结果,搜索用时 15 毫秒
71.
A longitudinal study of cognitive function after coronary artery bypass surgery examined 107 participants using 11 tests, preoperatively and at 6 days, 8 weeks, and 5 years after surgery. The overall neuropsychological (NP) change score declined at 6 days, showed some recovery at 8 weeks, and declined again at 5 years. The number of microemboli recorded during surgery, postoperative short-term cognitive change, and degree of recovery at 8 weeks were identified as predictors of change in NP score to 5 years. This suggests that even over a 5-year period, operative damage is detectable. Patients' vulnerability to short-term deterioration and resilience or ability to recover over a few weeks from operative cerebral insult are important processes of unknown mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
72.
How should interfering with the perception of items during study affect memory for those items? Recent research by J. Nairne (see, PA, Vol 76:7468) and E. Hirshman and N. Mulligan (see record 1991-26469-001) has demonstrated that backward pattern masking during study enhances later memory. This article examines whether traditional explanations of encoding benefits, including rehearsal, visual distinctiveness, and encoding effort, can account for this result. No evidence was found for any of these hypotheses. An explanation that focuses on the compensatory processing of higher level perceptual representations is proposed. This explanation provides a plausible explanation of the results of 7 experiments. The article concludes with a discussion of the implications of the explanation for perceptual priming and other manipulations of perceptual interference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
73.
We report a case of subcutaneous phaeohyphomycosis observed in a male patient presenting pulmonary sarcoidosis and submitted to corticosteroid treatment. He presented nodular erythematous-violaceous skin lesions in the dorsum of the right hand. Histopathological examination of the biopsied lesion revealed dematiaceous hyphae and yeast-like cells, with a granulomatous tissual reaction. The isolated fungus was identified as Phoma cava. A review of the literature on fungal infection caused by different Phoma species, is presented. The patient healed after therapy with amphotericin B. followed by itraconazole.  相似文献   
74.
The autosomal dominant multiple endocrine neoplasia type 2 syndromes (MEN 2) comprise three clinically distinct entities, MEN 2A, familial medullary thyroid carcinoma and MEN 2B, which share a common clinical feature: medullary thyroid carcinoma (MTC). MEN 2B is considered to have the most aggressive form of MTC. Therefore, early detection of MEN 2B in order to prevent potentially lethal MTC is important. More than 95% of all MEN 2B cases are caused by germline mutation at codon 918 (M918T) in exon 16 of the RET proto-oncogene. In this study, we demonstrate the presence of germline codon 883 mutation (A883F) in 2 of 3 unrelated MEN 2B cases without codon 918 mutation. Our data demonstrate a novel etiologic event which may have roles in predisposition to MEN 2B when present in the germline and in the pathogenesis of sporadic MTC when somatic.  相似文献   
75.
76.
Mutations in the RET proto-oncogene, which encodes a receptor tyrosine kinase, are associated with the pathogenesis of medullary thyroid carcinoma (MTC). Somatic mutations in RET, predominantly at codon 918, and very rarely at codon 883, have been found in a proportion of sporadic MTC. We have previously shown that approximately 80% of sporadic MTCs had at least one subpopulation with a somatic RET mutation. Uneven distribution of somatic mutation within a single tumor or among metastases from a single individual was notable. In the present study, we sought to correlate RET expression, as demonstrated by RET immunohistochemistry, with mutation status in sporadic MTC for each tumor. Seventy evaluable subpopulations, belonging to 28 unrelated sporadic cases, comprising primary MTC and metastases, were immunostained with two different polyclonal antibodies raised against the C-terminus of RET. The regional presence of codon 918 or 883 seemed to coincide with increased RET immunopositivity in at least 62 of 70 (89%, P < 0.000001) tumor subpopulations. The reasons for this concordance are not entirely clear but could be related to either RNA or protein stability. Preliminary studies have suggested that the presence of somatic codon 918 mutation in MTC has a prognostic significance. If these preliminary results prove true, then given our data, we can further explore the feasibility of RET immunocytochemistry as a rapid assessment for the presence of somatic codon 918 for molecular diagnostic and prognostic purposes.  相似文献   
77.
Acute hemorrhagic lung injury occurs in humans with anti-GBM antibody (Goodpasture's syndrome), however, the mechanism of this injury is still largely unknown. To date, treatment has been confined to steroids and plasmaphoresis. Infusion of anti-GBM antibody into rats caused lung injury with intra-alveolar hemorrhage and intrapulmonary accumulation of neutrophils. Lung injury was dependent on the presence of neutrophils and complement and required both TNF alpha and IL-1. Experiments employing blocking antibodies to adhesion molecules demonstrated requirements for the beta 1 integrin VLA-4, beta 2 integrins LFA-1 and Mac-1, and L-selection. The endothelial cell adhesion molecules, E-selectin and ICAM-1, were also required for the full development of lung injury. Inhibition of TNF alpha or IL-1 or adhesion molecules reduced both lung injury and tissue neutrophil accumulation. Thus, this study underscores cytokine and adhesion molecule requirements for neutrophil mediated injury in lung and kidney caused by anti-GBM, suggesting potential targets for the treatment of Goodpasture's syndrome in humans.  相似文献   
78.
Although other aromatic compounds (e.g., benzene, toluene, polycyclic aromatic hydrocarbons (PAH), etc.) have been thoroughly studied over the years, styrene has been given little attention probably due to its lower rate of industrial use. In addition, it is less toxic than benzene and PAH, proven carcinogens. However, it is classified as a mutagen and thus potentially carcinogenic. Its main use is in the production of the polymer polystyrene and in the production of plastics, rubber, resins, and insulators. Entry into the environment is mainly through industrial and municipal discharges. In this review, the toxicological effects of styrene on humans, animals, and plants are discussed. Its mode of entry and methods of monitoring its presence are examined. Although its effects on humans and aquatic life have been studied, the data on short- or long-term exposures to plants, birds, and land animals are insufficient to be conclusive. Since exposure to workers can result in memory loss, difficulties in concentration and learning, brain and liver damage, and cancer, development of accurate methods to monitor its exposure is essential. In addition, the review outlines the present state of styrene in the environment and suggests ways to deal with its presence. It might appear that the quantities are not sufficient to harm humans, but more data are necessary to evaluate its effect, especially on workers who are regularly exposed to it.  相似文献   
79.
An experimental investigation of the effect of sulphidation method of supported molybdenum catalysts used in the reduction of SO2 with Ch4 was carried out. Two sulphidation methods, one using H2S and the other using a mixture of SO2/CH4, are compared. The methods are evalauted with respect to molybdenum retention, extent of molybdenum sulphidation, and catalytic activity. Mo/Al2O3 catalysts sulphided with H2S are superior to those sulphided under SO2 and CH4 reaction conditions. Although complete sulphidation is never achieved in either of the two cases, the higher activity found with H2S-sulphided catalysts is attributed to a higher degree of molybdenum sulphidation resulting in a higher MoS2 content. The 15% Mo/Al2O3 catalyst sulphided with H2S at 600°C showed the highest activity and had the highest MoS2 content.  相似文献   
80.
The design and operation of a 100 kW, 140 GHz pulsed gyrotron are reported. To our knowledge, this is the highest frequency at which high gyrotron output power (>-100 kW) has been achieved. Results are presented for gyrotron operation in the range of magnetic field from 4 to 7 T, voltage from 23 to 80 kV and current up to 7.5 A. Near a value of magnetic field of 5.4 T, and output power of 100 kW was obtained at 140.4 GHz in single mode operation in the TE031 resonator mode.  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