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   309篇
  免费   9篇
电工技术   20篇
化学工业   66篇
金属工艺   1篇
机械仪表   4篇
建筑科学   3篇
能源动力   8篇
轻工业   9篇
水利工程   1篇
石油天然气   1篇
无线电   43篇
一般工业技术   64篇
冶金工业   77篇
原子能技术   2篇
自动化技术   19篇
  2023年   1篇
  2021年   2篇
  2020年   2篇
  2019年   4篇
  2018年   1篇
  2017年   1篇
  2016年   6篇
  2015年   5篇
  2014年   9篇
  2013年   8篇
  2012年   5篇
  2011年   15篇
  2010年   7篇
  2009年   7篇
  2008年   13篇
  2007年   11篇
  2006年   9篇
  2005年   10篇
  2004年   7篇
  2003年   7篇
  2002年   2篇
  2001年   7篇
  2000年   9篇
  1999年   11篇
  1998年   29篇
  1997年   29篇
  1996年   12篇
  1995年   15篇
  1994年   12篇
  1993年   11篇
  1992年   5篇
  1991年   3篇
  1990年   4篇
  1989年   7篇
  1988年   4篇
  1987年   5篇
  1986年   3篇
  1985年   2篇
  1984年   3篇
  1982年   2篇
  1981年   2篇
  1980年   1篇
  1979年   2篇
  1977年   1篇
  1976年   1篇
  1974年   2篇
  1973年   1篇
  1972年   1篇
  1969年   1篇
  1968年   1篇
排序方式: 共有318条查询结果,搜索用时 15 毫秒
221.
In order to investigate the health effects of NO2, emitted from gas cooking stoves, we compared the prevalence of several respiratory symptoms for people living in gas homes (homes with gas cooking stoves) with those for people living in electric homes (homes with electric cooking stoves) in Japan. The survey was conducted in September 1985, with a self-administered questionnaire. No statistically significant differences were found for several respiratory symptoms between electric homes and gas homes among both children (adjusted odds ratios: 0.64–1.80) and their parents (odds ratios: 0.39–0.94). This work represents a preliminary study in Japan. A longitudinal study should be conducted to further investigate the health effects associated with gas cooking stoves.  相似文献   
222.
The effects of the enclosure material to the electromagnetic force and the dynamic performances of the force have been measured in case of 3? fault and ?-? fault, using three phase enclosure type gas insulated bus (GIB) models. The analysis for the electromagnetic force has been performed and compared with the experimental results. Mild steel and stainless steel enclosure have little influence to the electromagnetic forces between the phase conductors, whereas the forces are fully reduced by the existence of aluminum alloy enclosure.  相似文献   
223.
The items, mentioned as postoperative complications in lung-resection surgery in the newest reports, are much the same to those in patients undergone general surgery. Dealing with perioperative complications in lung-resection surgery, it must be taken into account that lung resection always results in, more or less, loss of cardiopulmonary function and that most perioperative complications are caused by accidental circumstances. Perioperative risk must be assessed based upon the predicted postoperative cardio-pulmonary function, but not the frequency of perioperative complications. The role of unilateral pulmonary artery occlusion test and exercise test in lung-resection surgery, and their pathophysiological implications are discussed.  相似文献   
224.
A recognition system for connected digits, which uses a statistical classifier to identify words in speaker-independent continuous speech, is described. The system uses the multiple similarity method, a statistical pattern recognition technique. For evaluating word strings, the system uses a scoring method that is independent of the number of words in the strings. It is derived from the a posteriori probability that a subinterval corresponds to a correct word position, giving a word similarity value. The system evaluates a word string using dynamic programming and a parallel search procedure. Experiments for the contextual effect of the training data set, for validation of the search algorithm, and for a large quantity of unspecified speakers including 40 males and 40 females were performed. For connected digits (unknown word lengths test), the string recognition rates were 90.1%-95.1% for two, three, or four connected digits, where the equivalent word (digit) rates were 97.4%-98.4%  相似文献   
225.
We report five cases of pancreatitis in systemic lupus erythematosus. Three patients died. The cause of death was directly related to pancreatitis in two cases. Several causes of pancreatitis may be suspected: vasculitis, thrombosis when associated to antiphospholipid syndrome, biliary calculi, infection, metabolic abnormalities or adverse effects of therapy. About seventy cases of pancreatitis have been reported in systemic lupus erythematosus in the literature Pancreatitis was the inaugural sign of lupus in six cases. In 12 cases, besides lupus, no other cause of pancreatitis was found. However, pancreatic vasculitis or thrombosis was rarely demonstrated even in post-mortem examinations. The role of corticosteroids in pancreatitis in lupus is controversial since the evolution of pancreatitis in lupus is generally good with corticosteroids. We think that diagnosis of pancreatitis in lupus should not implicate discontinuation or decrease of corticosteroids dosage, unless their responsibility is absolutely demonstrated.  相似文献   
226.
A monolithic integration of an optical neurochip with variable interconnection capability is reported. The neurochip is a three-dimensional optoelectronic integrated circuit, in which a variable sensitivity photodetector is directly fabricated on a light emitting diode. The principle of operation and the fundamental characteristics of the monolithic neurochip are described in detail. The optical crosstalk was significantly reduced and the optical coupling efficiency between the light emitting diode and the variable sensitivity photodetector was improved as compared to the previous hybrid structure. The monolithic neurochip is suitable for a large scale integration because there is little optical crosstalk, high efficiency, and no need of optical alignment  相似文献   
227.
Several studies have indicated the possibility of using cholinesterase (ChE) inhibitors as therapeutic drugs for Alzheimer's disease. Metrifonate (MTF) is an organophosphorus compound that has been used in the treatment of schistosomiasis. In this study, we investigated the effects of MTF on the impairment of learning and memory, decreased ChE activity and extracellular acetylcholine (ACh) levels in basal forebrain (BF)-lesioned rats. The oral administration of MTF improved the BF-lesion-induced impairment of performance on passive avoidance task. Further, MTF reduced ChE activity in the cerebral cortex. In vivo brain microdialysis studies showed that MTF significantly increased the release of ACh, but decreased that of choline (Ch) in the cerebral cortex of BF-lesioned rats. These results indicated that MTF ameliorates the impairment of performance on passive avoidance task in BF-lesioned rats by increasing the extracellular ACh levels by inhibiting ChE. This suggested that MTF may be useful as a therapeutic drug for Alzheimer's disease.  相似文献   
228.
The HER-2/neu proto-oncogene is frequently amplified or overexpressed in human breast and ovarian cancers, and is significantly correlated with shorter survival. We have previously reported that the adenovirus type 5 early region 1A (E1A) gene product can repress HER-2/neu overexpression by repressing HER-2/neu promoter activity, and suppress the tumorigenic potential of HER-2/neu-overexpressing ovarian cancer cells. To examine E1A tumor suppressor function in breast cancer, we transduced E1A in vitro by adenovirus into both HER-2/neu-overexpressing and low expressing human breast cancer cell lines. In HER-2/neu-overexpressing cells, E1A greatly inhibited tumor cell growth in vitro. However, in HER-2/neu low expressing cancer cell lines, E1A had no significant effect on cell growth in culture medium. To test the therapeutic efficacy of E1A, we used both adenovirus-mediated and cationic liposome-mediated E1A gene delivery systems in an orthotopic breast cancer animal model. An advanced breast cancer model was established by inoculation of HER-2/neu-overexpressing human breast cancer cells in mammary fat pad and treated by local injections of either replication-deficient adenovirus expressing E1A, Ad.E1A(+) or a liposome-E1A DNA complex. As controls, mice bearing tumors were also treated with Ad.E1A(-) which is virtually the same adenovirus as Ad.E1A(+) except that E1A is deleted, a liposome-E1A frame-shift mutant DNA complex, or just PBS. In mice bearing a HER-2/neu-overexpressing breast cancer cell line, E1A delivered either by adenovirus or liposome significantly inhibited tumor growth and prolonged mouse survival compared with the controls. In fact, 60-80% of E1A-treated mice lived longer than 2 years versus only 0-20% of control mice (P<0.05). Western blot analysis showed that E1A protein was expressed in tumor tissue and immunohistochemical analysis showed that HER-2/neu p185 protein expression was suppressed. Taken together, our results indicated that both adenovirus and cationic liposome delivery systems were effective in transfering E1A gene for tumor suppression in a HER-2/neu-overexpressing breast cancer model.  相似文献   
229.
We investigated oxygen consumption and carbon dioxide production during treatment of hypoglycemia in infants of diabetic mothers (IDM) (n=11) and small-for-gestational-age (SGA) infants (n=6). Healthy newborn infants served as controls (n=16). The infants in both groups received normal enteral feedings and they were treated with intravenous glucose at a rate adjusted to increase plasma glucose concentration above 45 mg/dL. Oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured using indirect calorimetry and respiratory quotient (RQ) was calculated. Measurements were performed immediately after the correction of hypoglycemia (6-10 hr), and 24, 72, and 120 hr later. After initiation of treatment, and 24 hr later mean VCO2 and RQ were significantly higher in the IDM and the SGA infants than in healthy infants. 72 and 120 hr after the first measurement, the IDM did not differ from the healthy controls, whereas in the SGA infants mean VCO2 and VO2 were still significantly increased. In the SGA infants, the hypermetabolism was sustained during whole study period. Our results indicate that the metabolic defect resulting in hypoglycemia is different between the SGA and IDM infants. However, the treatment with supplemental glucose is necessary to both groups.  相似文献   
230.
Photoluminescence spectra of fullerene films were obtained in the range of 0.8∼1.8 eV by using a semiconductor pin Ge-detector and a photomultiplier. The effects of air intercalation on the optical properties of the fullerene film are discussed.  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