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   1812046篇
  免费   50994篇
  国内免费   18984篇
电工技术   51348篇
技术理论   56篇
综合类   25583篇
化学工业   322179篇
金属工艺   80523篇
机械仪表   61962篇
建筑科学   71261篇
矿业工程   22203篇
能源动力   58914篇
轻工业   130068篇
水利工程   20470篇
石油天然气   58537篇
武器工业   2735篇
无线电   227762篇
一般工业技术   315733篇
冶金工业   188643篇
原子能技术   36728篇
自动化技术   207319篇
  2022年   18787篇
  2021年   27481篇
  2020年   21102篇
  2019年   21992篇
  2018年   23258篇
  2017年   23742篇
  2016年   29396篇
  2015年   28851篇
  2014年   43647篇
  2013年   105128篇
  2012年   54328篇
  2011年   68113篇
  2010年   59706篇
  2009年   67108篇
  2008年   60892篇
  2007年   57281篇
  2006年   61894篇
  2005年   54044篇
  2004年   50570篇
  2003年   49398篇
  2002年   47517篇
  2001年   44367篇
  2000年   43283篇
  1999年   44218篇
  1998年   56429篇
  1997年   47365篇
  1996年   42379篇
  1995年   36235篇
  1994年   33310篇
  1993年   31797篇
  1992年   28279篇
  1991年   24994篇
  1990年   24928篇
  1989年   23675篇
  1988年   22067篇
  1987年   19972篇
  1986年   19271篇
  1985年   22375篇
  1984年   22485篇
  1983年   20453篇
  1982年   19450篇
  1981年   19492篇
  1980年   18065篇
  1979年   18567篇
  1978年   17746篇
  1977年   17424篇
  1976年   18250篇
  1975年   15978篇
  1974年   15486篇
  1973年   15585篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
根据电气工程及其自动化这门专业的特点以及学这门专业的学生的知识和能力体系的要求,对我国现在的人才培养的模式进行了一定的改革。对专业的基础课和实践教学环节都进行了一定程度的改革与创新,优化了专业课中的人才培养方面的方案。对于教学内容和教学方法进行了一定程度上的调整和完善。  相似文献   
992.
Antibiotics are potentially a cause of neurotoxicity in dialysis patients, the most common are the beta‐lactams as ceftazidime and cefepime, and few cases have been reported after piperacillin/tazobactam use. This report presents a case of a hypertensive and diabetic 67‐year‐old woman in regular hemodialysis, which previously had a stroke. She was hospitalized presenting pneumonia, which was initially treated with cefepime. Two days after treatment, she presented dysarthria, left hemiparesis, ataxia, and IX and X cranial nerves paresis. Computed tomography showed no acute lesions and cefepime neurotoxicity was hypothesized, and the antibiotic was replaced by piperacillin/tazobactam. The neurologic signs disappeared; however, 4 days after with piperacillin/tazobactam treatment, the neurological manifestations returned. A new computed tomography showed no new lesions, and the second antibiotic regimen withdrawn. After two hemodialysis sessions, the patient completely recovered from neurological manifestations. The patient presented sequentially neurotoxicity caused by two beta‐lactams antibiotics. This report meant to alert clinicians that these antibiotics have dangerous neurological effects in chronic kidney disease patients.  相似文献   
993.
Based on the phase transformation theories, especially the T0 concept of bainite transformation, alloy optimisation of bainitic steel with carbides has been carried out aiming at the produce of plastic mould with large cross-section. The effect of manganese and silicon on proeutectoid ferrite and bainite transformation is explored by dilatometric analysis, XRD and different microscopy techniques. The results show that after the alloy optimisation, the transformation of proeutectoid ferrite is suppressed and when the cooling rate is lower than 0·1°C?s??1, the new lower bainite transformation appears by decreasing carbon capacity of austenite and promoting carbide precipitation. Industrial production proves that the optimised alloy SDP1 can meet the demand for the plastic mould with the thickness of 1050?mm.  相似文献   
994.
Linear friction welding of the Ti6Al4V alloy is studied. A new definition of the energy input rate is proposed, based on an integration over time of the in-plane force and velocity; a strong correlation with the upset rate is then found. The effective friction coefficient is estimated to be 0·5±0·1 for varying frequencies and amplitudes, with only a weak dependence on the processing conditions displayed. A model is proposed that accounts for both the conditioning and equilibrium stages of the process, which is shown to be in good agreement with the experimental data. The model is used to study the mechanism by which the flash is formed. A criterion is proposed by which the rippled nature of its morphology can be predicted.  相似文献   
995.
In this paper, the development of the models for the prediction of rock mass P wave velocity is presented. For model development, the database of 53 cases including widely used and recorded drilling parameters and P wave velocity was constructed from the field studies conducted in 13 open pit lignite mines. Both conventional linear, non-linear multiple regression and Adaptive Neuro Fuzzy Inference System (ANFIS) were used for model development. Prediction performance indicators showed that ANFIS model presented the best performance and it can successfully be used for the preliminary prediction of P wave velocities of rock masses.  相似文献   
996.
997.
As a decisive attribute, flavour could be influenced by HP treatments through multiple physical and chemical pathways within the high pressure (HP)-assisted meat curing process. This investigation aimed to identify the major pathway influencing volatile flavour patterns of two representative vinasse-cured duck (VCD) products with HP treatments (150–300 MPa/15 min), including wet and dry types, by employing headspace fingerprinting as an untargeted approach. Results suggested that HP treatments greatly lowered moisture contents and increased Warner-Bratzler shear force and thiobarbituric acid reactive substances of the cured samples. According to multivariate models, the volatile flavour patterns of the HP-processed VCD could be clearly separated from the unprocessed samples, but the VCD pressurised at different intensities represented similar volatile fingerprinting, which was validated by e-nose analysis. The discriminant analysis (OPLS-DA) model outlined vinasse-derived ethanol, acetic acid, 3-methyl-1-butanol, 2-methyl-1-butanol, phenethyl alcohol and 2-methyl-3-octanone as the major discriminant aromas across the unpressurised and pressurised samples.  相似文献   
998.
Journal of Computer and Systems Sciences International - The height of a building is a basic characteristic needed for analytical services. It can be used to evaluate the population and functional...  相似文献   
999.
Multimedia Tools and Applications - Emotions are spontaneous feelings that are accompanied by fluctuations in facial muscles, which leads to facial expressions. Categorization of these facial...  相似文献   
1000.
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