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   2067篇
  免费   146篇
  国内免费   29篇
电工技术   45篇
综合类   11篇
化学工业   473篇
金属工艺   54篇
机械仪表   66篇
建筑科学   88篇
矿业工程   4篇
能源动力   128篇
轻工业   254篇
水利工程   35篇
石油天然气   59篇
武器工业   2篇
无线电   208篇
一般工业技术   364篇
冶金工业   129篇
原子能技术   10篇
自动化技术   312篇
  2023年   34篇
  2022年   88篇
  2021年   136篇
  2020年   126篇
  2019年   118篇
  2018年   148篇
  2017年   115篇
  2016年   136篇
  2015年   76篇
  2014年   109篇
  2013年   188篇
  2012年   136篇
  2011年   110篇
  2010年   93篇
  2009年   74篇
  2008年   54篇
  2007年   52篇
  2006年   36篇
  2005年   32篇
  2004年   25篇
  2003年   17篇
  2002年   16篇
  2001年   13篇
  2000年   16篇
  1999年   19篇
  1998年   43篇
  1997年   36篇
  1996年   18篇
  1995年   21篇
  1994年   16篇
  1993年   16篇
  1992年   9篇
  1991年   8篇
  1990年   6篇
  1989年   14篇
  1988年   10篇
  1987年   7篇
  1986年   6篇
  1985年   11篇
  1983年   3篇
  1982年   6篇
  1981年   4篇
  1980年   6篇
  1979年   3篇
  1978年   3篇
  1977年   3篇
  1976年   8篇
  1975年   3篇
  1973年   4篇
  1972年   3篇
排序方式: 共有2242条查询结果,搜索用时 15 毫秒
71.
The increasing global energy demand and declination of oil reservoir in recent years cause the researchers attention focus on the enhancement of oil recovery approaches. One of the extensive applicable methods for enhancement of oil recovery, which has great efficiency and environmental benefits, is carbon dioxide injection. The CO2 injection has various effects on the reservoir fluid, which causes enhancement of recovery. One of these effects is extraction of lighter components of crude oil, which straightly depends on solubility of hydrocarbons in carbon dioxide. In order to better understand of this parameter, in this study, Least squares support vector machine (LSSVM) algorithm was developed as a novel predictive tool to estimate solubility of alkane in CO2 as function of carbon number of alkane, carbon dioxide density, pressure, and temperature. The predicting model outputs were compared with the extracted experimental solubility from literature statistically and graphically. The comparison showed the great ability and high accuracy of developed model in prediction of solubility.  相似文献   
72.
This research evaluates the energy efficiency and productivity growth in the industrial sector over the period of 1999 till 2013 using data envelopment analysis (DEA). Two cases are analyzed; in the first case (GVA), the output is the gross value added, whereas two outputs are considered in the second case (GCO), CO2 emission and GVA. Five key input factors are considered in both cases. From DEA window analysis, the technical inefficiency (TIE) values are zeros in windows (2001–2005) till (2003–2007), (2007–2011), and (2008–2012), whereas the pure technical inefficiency (PTIE) values are zeros in windows (1999–2003) till (2003–2007). Finally, the scale inefficiency (SIE) values are zeros in windows (2001–2005) till (2003–2007). These results help policy planners on how to better utilize resources and management efficiency over time and guide operational managers when to increase or decrease the scale. Moreover, the averages of inefficiency values in the GVA case are smaller than their corresponding in the GCO case, which indicates the negative effect of CO2 emission on efficiency. Further, Malmquist index is estimated for three 5-year energy plans. The productivity index is found less than one for the third plan (2009–2013), which indicates a decrease productivity growth. In conclusions, research results provide valuable support when assessing the progress of energy efficiency and productivity in industrial sector.  相似文献   
73.
74.
Mobile app reviews by users contain a wealth of information on the issues that users are experiencing. For example, a review might contain a feature request, a bug report, and/or a privacy complaint. Developers, users and app store owners (e.g. Apple, Blackberry, Google, Microsoft) can benefit from a better understanding of these issues – developers can better understand users’ concerns, app store owners can spot anomalous apps, and users can compare similar apps to decide which ones to download or purchase. However, user reviews are not labelled, e.g. we do not know which types of issues are raised in a review. Hence, one must sift through potentially thousands of reviews with slang and abbreviations to understand the various types of issues. Moreover, the unstructured and informal nature of reviews complicates the automated labelling of such reviews. In this paper, we study the multi-labelled nature of reviews from 20 mobile apps in the Google Play Store and Apple App Store. We find that up to 30 % of the reviews raise various types of issues in a single review (e.g. a review might contain a feature request and a bug report). We then propose an approach that can automatically assign multiple labels to reviews based on the raised issues with a precision of 66 % and recall of 65 %. Finally, we apply our approach to address three proof-of-concept analytics use case scenarios: (i) we compare competing apps to assist developers and users, (ii) we provide an overview of 601,221 reviews from 12,000 apps in the Google Play Store to assist app store owners and developers and (iii) we detect anomalous apps in the Google Play Store to assist app store owners and users.  相似文献   
75.
In this research work, Zinc(II) and Aluminum(III)-IIP's were synthesized by optimizing the amount of methacrylic acid as monomer, divinylbenzene as cross-linker. The IIP's were functionalized with 8-hydroxy quinolone complexes of the two metal ions under thermal conditions by copolymerization with monomer and cross-linker. The IIP's and Non-IIP's were characterized using FT-IR, TGA, and SEM analysis. A quite remarkable difference in the size was observed of the polymers (Zn(II) 1.0 µm and Al(III) 0.1 µm). A stronger affinity was observed with IIP in comparison with Non-IIP at pH 3.1 and 4.5 for Zn(II) and Al(III) ions on their respective polymers.  相似文献   
76.
To optimize mitigation, preparedness, response, and recovery procedures for infrastructure systems, it is essential to use accurate and efficient means to evaluate system reliability against probabilistic events. The predominant approach to quantify the impact of natural disasters on infrastructure systems is the Monte Carlo approach, which still suffers from high computational cost, especially when applied to large systems. This article presents a deep learning framework for accelerating seismic reliability analysis, on a transportation network case study. Two distinct deep neural network surrogates are constructed and studied: (1) a classifier surrogate that speeds up the connectivity determination of networks and (2) an end‐to‐end surrogate that replaces modules such as roadway status realization, connectivity determination, and connectivity averaging. Numerical results from k‐terminal connectivity analysis of a California transportation network subject to a probabilistic earthquake event demonstrate the effectiveness of the proposed surrogates in accelerating reliability analysis while achieving accuracies of at least 99%.  相似文献   
77.
78.
Li  Wei  Kiaghadi  Amin  Dawson  Clint 《Neural computing & applications》2021,33(11):5571-5580
Neural Computing and Applications - Accurate and efficient models for rainfall–runoff (RR) simulations are crucial for flood risk management. Recently, the success of the recurrent neural...  相似文献   
79.

In the present work, we propose a green and sustainable strategy for eco-friendly surface modification of wool structure using biosynthesized kerationlytic proteases, from C4-ITA-EGY, Streptomyces harbinensis S11-ITA-EGY and Streptomyces carpaticus S33-ITA-EGY, followed by subsequent environmentally sound functionalization of the bio-treated substrates using ZnONPs, ZrO2NPs, ascorbic acid and vanillin, individually, to provide durable antibacterial as well as UV-protection properties. Both surface modification changes and the extent of functionalization of the final products were characterized by SEM, EDX, antibacterial efficacy, UV-blocking ability, loss in weight, nitrogen content and durability to washing analysis. The obtained data reveal that the developed green wool fabrics exhibit outstanding durable antibacterial activity and UV-blocking ability for fabricating multi-functional textile products that can be utilized in a wide range of sustainable protective textiles, irrespective of the used post-finishing formulation ingredients. The results also show that both modification and functionalization processes are governed by the type of enzyme and kind of active material respectively. Moreover, the biosynthesized kerationlytic proteases could be accessibly used to remove protein-based stains like blood and egg.

Graphical abstract
  相似文献   
80.
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