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   13014篇
  免费   467篇
  国内免费   53篇
电工技术   261篇
综合类   18篇
化学工业   2399篇
金属工艺   374篇
机械仪表   364篇
建筑科学   229篇
矿业工程   73篇
能源动力   714篇
轻工业   1189篇
水利工程   191篇
石油天然气   83篇
无线电   1627篇
一般工业技术   2806篇
冶金工业   1569篇
原子能技术   201篇
自动化技术   1436篇
  2024年   32篇
  2023年   186篇
  2022年   491篇
  2021年   514篇
  2020年   417篇
  2019年   415篇
  2018年   568篇
  2017年   518篇
  2016年   494篇
  2015年   288篇
  2014年   456篇
  2013年   906篇
  2012年   529篇
  2011年   690篇
  2010年   549篇
  2009年   538篇
  2008年   486篇
  2007年   402篇
  2006年   344篇
  2005年   268篇
  2004年   247篇
  2003年   224篇
  2002年   186篇
  2001年   147篇
  2000年   149篇
  1999年   159篇
  1998年   363篇
  1997年   236篇
  1996年   256篇
  1995年   224篇
  1994年   183篇
  1993年   175篇
  1992年   145篇
  1991年   155篇
  1990年   119篇
  1989年   115篇
  1988年   132篇
  1987年   113篇
  1986年   90篇
  1985年   119篇
  1984年   96篇
  1983年   111篇
  1982年   101篇
  1981年   92篇
  1980年   80篇
  1979年   56篇
  1978年   49篇
  1977年   59篇
  1976年   76篇
  1975年   37篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
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   
4.
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   
5.

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   
6.
Crystalline quartz has long been identified as among the weakest of abundant crustal minerals. This weakness is particularly evident around the αβ phase inversion at 573°C, in which Si–O bonds undergo a displacive structural transformation from trigonal to hexagonal symmetry. Here we present data using indentation testing methodologies that highlight the precipitous extent of the transformational weakening. Although the indentations are localized over relatively small specimen contact areas, the data quantify the essential deformation and fracture properties of quartz in a predominantly (but not exclusively) compressive stress field, at temperatures and pressures pertinent to conditions in the earth's crust.  相似文献   
7.
8.
9.
In this study the effects of high temperature and moisture on the impact damage resistance and mechanical strength of Nextel 610/alumina silicate ceramic matrix composites were experimentally evaluated. Composite laminates were exposed to either a 1050°C isothermal furnace-based environment for 30 consecutive days at 6 h a day, or 95% relative humidity environment for 13 consecutive days at 67°C. Low velocity impact, tensile and short beam strength tests were performed on both ambient and environmentally conditioned laminates and damage was characterized using a combination of non-destructive and destructive techniques. High temperature and humidity environmental exposure adversely affected the impact resistance of the composite laminates. For all the environments, planar internal damage area was greater than the back side dent area, which in turn was greater than the impactor side dent area. Evidence of environmental embrittlement through a stiffer tensile response was noted for the high temperature exposed laminates while the short beam strength tests showed greater propensity for interlaminar shear failure in the moisture exposed laminates. Destructive evaluations exposed larger, more pronounced delaminations in the environmentally conditioned laminates in comparison to the ambient ones. External damage metrics of the impactor side dent depth and area directly influenced the post-impact tensile strength of the laminates while no such trend between internal damage area and residual strength could be ascertained.  相似文献   
10.
Multimedia Tools and Applications - The video surveillance activity generates a vast amount of data, which can be processed to detect miscreants. The task of identifying and recognizing an object...  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