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   585114篇
  免费   7627篇
  国内免费   1487篇
电工技术   11669篇
综合类   962篇
化学工业   85212篇
金属工艺   24110篇
机械仪表   20515篇
建筑科学   14215篇
矿业工程   2530篇
能源动力   14688篇
轻工业   49213篇
水利工程   5748篇
石油天然气   8137篇
武器工业   75篇
无线电   72783篇
一般工业技术   115297篇
冶金工业   101364篇
原子能技术   10600篇
自动化技术   57110篇
  2021年   4389篇
  2019年   4185篇
  2018年   13602篇
  2017年   14041篇
  2016年   10939篇
  2015年   5167篇
  2014年   8160篇
  2013年   24122篇
  2012年   15113篇
  2011年   24727篇
  2010年   20650篇
  2009年   21590篇
  2008年   22293篇
  2007年   23750篇
  2006年   15056篇
  2005年   16710篇
  2004年   14894篇
  2003年   14280篇
  2002年   13005篇
  2001年   12605篇
  2000年   12162篇
  1999年   12555篇
  1998年   29330篇
  1997年   21196篇
  1996年   16815篇
  1995年   13104篇
  1994年   11770篇
  1993年   11432篇
  1992年   8828篇
  1991年   8387篇
  1990年   8148篇
  1989年   7718篇
  1988年   7520篇
  1987年   6459篇
  1986年   6425篇
  1985年   7614篇
  1984年   6963篇
  1983年   6459篇
  1982年   5894篇
  1981年   6147篇
  1980年   5683篇
  1979年   5518篇
  1978年   5248篇
  1977年   6202篇
  1976年   7874篇
  1975年   4691篇
  1974年   4509篇
  1973年   4567篇
  1972年   3701篇
  1971年   3377篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
3.
Virtual Reality - It is generally accepted that natural environments reduce stress and improve mood. Since access to natural environments is sometimes limited, virtual natural environments,...  相似文献   
4.
The effect of microwave roasting parameters (300, 450 and 600 W; 5, 10 and 15 min) on acrylamide content in sorghum grain was determined using High Pressure Liquid Chromatography (HPLC)-photo diode array (PDA) detector coupled with C-18 column. Samples roasted at 300 and 450 W did not possess acrylamide, whereas 600 W (15 min) favoured formation of 2740.19 µg/kg of acrylamide, levels far exceeding the defined European Union (EU) limits. The chronic daily intake (CDI) for acrylamide through consumption of such grain flour was 3.25–9.5-fold higher to Joint FAO/WHO Expert Committee on Food Additives (JECFA) defined high exposure limits. The margin of exposure (MOE) values ranged from 4.3 to 12.76 and from 11.07 to 32.27 for neoplastic and neurological effects, respectively, demonstrating high exposure and serious health concerns associated with dietary intake of this toxicant. This study assesses the risk for the Indian population and highlights the importance of optimising process parameters for food product to minimise such exposure risks.  相似文献   
5.
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized...  相似文献   
6.
Multimedia Tools and Applications - Currently, Deep Learning is playing an influential role for Image analysis and object classification. Maize’s diseases reduce production that subsequently...  相似文献   
7.

A large amount of data and applications need to be shared with various parties and stakeholders in the cloud environment for storage, computation, and data utilization. Since a third party operates the cloud platform, owners cannot fully trust this environment. However, it has become a challenge to ensure privacy preservation when sharing data effectively among different parties. This paper proposes a novel model that partitions data into sensitive and non-sensitive parts, injects the noise into sensitive data, and performs classification tasks using k-anonymization, differential privacy, and machine learning approaches. It allows multiple owners to share their data in the cloud environment for various purposes. The model specifies communication protocol among involved multiple untrusted parties to process owners’ data. The proposed model preserves actual data by providing a robust mechanism. The experiments are performed over Heart Disease, Arrhythmia, Hepatitis, Indian-liver-patient, and Framingham datasets for Support Vector Machine, K-Nearest Neighbor, Random Forest, Naive Bayes, and Artificial Neural Network classifiers to compute the efficiency in terms of accuracy, precision, recall, and F1-score of the proposed model. The achieved results provide high accuracy, precision, recall, and F1-score up to 93.75%, 94.11%, 100%, and 87.99% and improvement up to 16%, 29%, 12%, and 11%, respectively, compared to previous works.

  相似文献   
8.
Multimedia Tools and Applications - The three-dimensional models of brain tumors serve as diagnostic assistance for physicians, surgeons, and radiologists. The proposed system establishes an...  相似文献   
9.
Engineering new glass compositions have experienced a sturdy tendency to move forward from (educated) trial-and-error to data- and simulation-driven strategies. In this work, we developed a computer program that combines data-driven predictive models (in this case, neural networks) with a genetic algorithm to design glass compositions with desired combinations of properties. First, we induced predictive models for the glass transition temperature (Tg) using a dataset of 45,302 compositions with 39 different chemical elements, and for the refractive index (nd) using a dataset of 41,225 compositions with 38 different chemical elements. Then, we searched for relevant glass compositions using a genetic algorithm informed by a design trend of glasses having high nd (1.7 or more) and low Tg (500 °C or less). Two candidate compositions suggested by the combined algorithms were selected and produced in the laboratory. These compositions are significantly different from those in the datasets used to induce the predictive models, showing that the used method is indeed capable of exploration. Both glasses met the constraints of the work, which supports the proposed framework. Therefore, this new tool can be immediately used for accelerating the design of new glasses. These results are a stepping stone in the pathway of machine learning-guided design of novel glasses.  相似文献   
10.
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