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   5418篇
  免费   282篇
  国内免费   45篇
电工技术   117篇
综合类   51篇
化学工业   1319篇
金属工艺   156篇
机械仪表   160篇
建筑科学   268篇
矿业工程   36篇
能源动力   344篇
轻工业   788篇
水利工程   43篇
石油天然气   79篇
武器工业   12篇
无线电   228篇
一般工业技术   807篇
冶金工业   511篇
原子能技术   48篇
自动化技术   778篇
  2024年   18篇
  2023年   46篇
  2022年   135篇
  2021年   199篇
  2020年   137篇
  2019年   153篇
  2018年   207篇
  2017年   223篇
  2016年   225篇
  2015年   195篇
  2014年   249篇
  2013年   507篇
  2012年   289篇
  2011年   358篇
  2010年   317篇
  2009年   258篇
  2008年   246篇
  2007年   227篇
  2006年   161篇
  2005年   104篇
  2004年   141篇
  2003年   139篇
  2002年   161篇
  2001年   96篇
  2000年   83篇
  1999年   70篇
  1998年   147篇
  1997年   102篇
  1996年   55篇
  1995年   47篇
  1994年   60篇
  1993年   46篇
  1992年   25篇
  1991年   16篇
  1990年   22篇
  1989年   19篇
  1988年   16篇
  1987年   11篇
  1986年   12篇
  1985年   26篇
  1984年   20篇
  1983年   17篇
  1982年   22篇
  1981年   21篇
  1980年   17篇
  1977年   13篇
  1976年   23篇
  1975年   9篇
  1974年   11篇
  1973年   6篇
排序方式: 共有5745条查询结果,搜索用时 0 毫秒
1.
Physically based simulation of human hair is a well studied and well known problem. But the “pure” physically based representation of hair (and other animation elements) is not the only concern of the animators, who want to “control” the creation and animation phases of the content. This paper describes a sketch-based tool, with which a user can both create hair models with different styling parameters and produce animations of these created hair models using physically and key frame-based techniques. The model creation and animation production tasks are all performed with direct manipulation techniques in real-time.  相似文献   
2.
The alarm lists presented to control center operators are usually difficult to interpret. The authors present an expert system that processes the alarm lists in Portuguese control centers. This system makes an intelligent synthesis of the available information and presents it in a flexible and structured way. It uses an original approach to deal with temporal reasoning and real-time constraints. The system incorporates an explanation module that enables its use as a tutor for novice operators  相似文献   
3.
4.
Cysticercosis is a severe public health problem in several regions of Asia, Africa and Latin America. Epidemiologic studies based on the frequency of cases observed in specialized neurology, neurosurgery and computed tomography services, at autopsy and in seroepidemiologic studies do not permit the determination of the true prevalence of the disease in the population. The objective of the present study was to investigate the prevalence of cysticercosis by compulsory notification. The coefficient of prevalence was 54 cases/100,000 inhabitants in the municipality of Ribeir?o Preto. The results also indicated that cysticercosis is not under control in our region since 21% of cases presented the active form of the disease. Compulsory notification proved to be a valuable resource for the epidemiologic study of cysticercosis, also permitting the mapping of more affected areas for a better direction of prevention strategies.  相似文献   
5.
The authors report the case of a 32 year old woman who was shot with a shotgun. Acute inferior wall infarction was detected fortuitously on electrocardiography and coronary angiography showed occlusion of the right coronary artery with lead shot. The single coronary lesion, absence, of other cardiac complications (haemopericardium, cardiac perforation, ...) and the favourable outcome with conservative medical treatment has not been previously reported to the authors' knowledge.  相似文献   
6.
In this study forecast of Turkey's net electricity energy consumption on sectoral basis until 2020 is explored. Artificial neural networks (ANN) is preferred as forecasting tool. The reasons behind choosing ANN are the ability of ANN to forecast future values of more than one variable at the same time and to model the nonlinear relation in the data structure. Founded forecast results by ANN are compared with official forecasts.  相似文献   
7.
An experimental study is performed using an infrared thermovision to monitor temperature distribution over a plate-fin surface inside the plate finned-tube heat exchangers. The differentiation of the temperature function is derived to determine the local convective heat transfer coefficients on the tested fin, using a local element lumped conduction equation included the convective effect on the boundaries with experimental data. It is disclosed that the infrared thermography is capable of rapidly detecting location and extent of transition and separation regions of the boundary layer over the whole surface of the tested models. Through the comparison of the test results on the strategy region of the in-line and staggered arrangements, it is more easy to understand or interpret the detailed dynamic phenomena of flow existed in the heat exchangers. In addition, the experimental results demonstrate that the averaged heat transfer coefficient of staggered configuration is 14-32% higher than that of in-lined configuration  相似文献   
8.
通过偏光显微镜观察了石油系油浆(LH)与煤系闪蒸油(SN)焦化后所得焦块的光学结构。结果表明,在较宽条件下两种原料单独焦化均得不到取向度高的流线型结构。将两种原料以一定比例混合后先热解丙焦化所得焦块的光学结构明显好于二者混合后直接焦化所得焦块的光学结构,其中LH和SN以3:2的重量比混合后在440℃、1MPa下热解3.5h然后再在530℃、1MPa下焦化8h所得焦块为具有较高取向度的流线型结构,适合于作为针状焦的起始原料。  相似文献   
9.
10.
A new method for the isolation of glucose repression-insensitive mutants in the methylotrophic yeast Pichia pinus was developed. The method is based on screening of small suspension samples derived from 2-deoxyglucose-resistant colonies for alcohol oxidase activity. Alcohol oxidase activity was evaluated by determination of formaldehyde excreted by cells. Mutants with glucose non-repressible alcohol oxidase and catalase synthesis were obtained. All mutants grew poorly on D -xylose compared to the wild type, whereas growth on L -arabinose was similar to the wild type. Changes in the glucose transport system were suggested to be responsible for altered growth characteristics and defective glucose repression.  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