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   586篇
  免费   24篇
  国内免费   3篇
电工技术   9篇
化学工业   169篇
金属工艺   5篇
机械仪表   13篇
建筑科学   17篇
能源动力   21篇
轻工业   79篇
水利工程   6篇
石油天然气   2篇
无线电   19篇
一般工业技术   95篇
冶金工业   45篇
原子能技术   5篇
自动化技术   128篇
  2023年   10篇
  2022年   24篇
  2021年   28篇
  2020年   16篇
  2019年   19篇
  2018年   21篇
  2017年   12篇
  2016年   25篇
  2015年   12篇
  2014年   18篇
  2013年   42篇
  2012年   47篇
  2011年   31篇
  2010年   31篇
  2009年   36篇
  2008年   24篇
  2007年   21篇
  2006年   27篇
  2005年   15篇
  2004年   12篇
  2003年   17篇
  2002年   11篇
  2001年   10篇
  2000年   4篇
  1999年   11篇
  1998年   18篇
  1997年   14篇
  1996年   12篇
  1995年   5篇
  1994年   4篇
  1993年   3篇
  1992年   3篇
  1991年   2篇
  1990年   2篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1985年   4篇
  1983年   3篇
  1982年   3篇
  1980年   3篇
  1979年   2篇
  1978年   1篇
  1977年   2篇
  1976年   2篇
  1975年   1篇
  1974年   2篇
排序方式: 共有613条查询结果,搜索用时 15 毫秒
601.
Two different types of adipose depots can be observed in mammals: white adipose tissue (WAT) and brown adipose tissue (BAT). The primary role of WAT is to deposit surplus energy in the form of triglycerides, along with many metabolic and hormonal activities; as thermogenic tissue, BAT has the distinct characteristic of using energy and glucose consumption as a strategy to maintain the core body temperature. Under specific stimuli—such as exercise, cold exposure, and drug treatment—white adipocytes can utilize their extraordinary flexibility to transdifferentiate into brown-like cells, called beige adipocytes, thereby acquiring new morphological and physiological characteristics. For this reason, the process is identified as the ‘browning of WAT’. We evaluated the ability of some drugs, including GW501516, sildenafil, and rosiglitazone, to induce the browning process of adult white adipocytes obtained from differentiated mesenchymal stromal cells (MSCs). In addition, we broadened our investigation by evaluating the potential browning capacity of IRISIN, a myokine that is stimulated by muscular exercises. Our data indicate that IRISIN was effective in promoting the browning of white adipocytes, which acquire increased expression of UCP1, increased mitochondrial mass, and modification in metabolism, as suggested by an increase of mitochondrial oxygen consumption, primarily in presence of glucose as a nutrient. These promising browning agents represent an appealing focus in the therapeutic approaches to counteracting metabolic diseases and their associated obesity.  相似文献   
602.
Clean Technologies and Environmental Policy - Objective is to analyze the economic feasibility of implementing a greenhouse in a hydroponics production system in substrate (sand) on a small family...  相似文献   
603.
604.
A convenient synthesis of a broad series of thirteen examples of alkyne-spacer derivatives 2 from the well-known Sonogashira cross-coupling reaction on diazenyl-pyrazolo[1,5-a]pyrimidin-2-amine compounds 1 is reported. The reactivity of heterocycles 1 due the presence of selected electron-donor (EDG) and electron-withdrawing (EWG) groups attached to different alkynes was evaluated. Also, the reactional versatility due the position variation of the bromo atom at the scaffolds 1 was also investigated. In general, derivatives presented strong absorption bands at the 250–500 nm optical window and UV to cyan emission properties. Also, the redox analysis was recorded by electrochemical cyclic voltammetry technique. For HSA biomacromolecule assays, spectroscopic studies by UV-Vis, steady-state and time-resolved emission fluorescence, and molecular docking calculations evidenced the ability of each compound to establish interactions with human serum albumin (HSA). Finally, the behavior presented for this new class of heterocycles makes them a promising tool as optical sensors for albumins.  相似文献   
605.
We aimed at characterising the nonthermal technologies resistance profile of two Escherichia coli strains isolated from pasteurised milk and described as moderate-to-high heat resistance (MHR) (60°C/6 min) harbouring or not a transmissible locus of stress tolerance (tLST). The characterisation was carried out applying optimised conditions of ultraviolet-C light-emitting diodes (UVC-LED) (4950 mJ/cm2), ultrasound (US) (299 W) and their combination (UVC-LED + US). Both strains were more sensitive to UVC-LED (4.5–1.5 log cfu/mL) than to US (<1 log cfu/mL) or UVC-LED + US (4.5–1.5 log cfu/mL), which did not exhibit synergism. Thus, UVC-LED is a promising technology to eliminate E. coli harbouring tLST.  相似文献   
606.
This paper, based on the PALIO Project within the fifth Research Framework of the European Commission, deals with an information tourist service accessible through mobile phones by means of the Wireless Application Protocol (WAP). We have considered a Global System for Mobile communications (GSM) network where the WAP traffic is transported by the Short Message Service (SMS) on a logical channel that also conveys signaling messages. Suitable models have been considered for both WAP browsing traffic and signaling traffic. We have proposed a theoretical approach to evaluate the mean delay to browse a WAP page taking into account the impact of the signaling load. Analytical predictions have been validated through comparisons with simulation results. Moreover, we have also considered a specific Quality of Service (QoS) requirement in terms of the maximum deck transmission delay that is guaranteed in 95 per cent of cases. Consequently, it has been possible to evaluate the number of WAP users that can be supported per cell. The study carried out in this paper permits to prove the feasibility for the envisaged mobile service based on WAP and it also allows dimensioning WAP pages so that each user experiences reasonable browsing delays. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
607.
Dam construction and streamflow regulation are increasing throughout the world, with impacts in impounded aquatic ecosystems. Hydropower dams, some of them causing a phenomenon called “hydropeaking” during their operation, are known for having a variety of impacts on downstream aquatic biota, particularly fish, and respective habitat. This can result in significant changes, from the community (e.g., fish assemblage structure) to the individual level (e.g., physiological and behavioural adjustments). Researchers and managers involved in the assessment of hydropeaking impacts must be resourceful and use methods that allow their precise evaluation, from large to fine-scale habitat and biological responses. In the last decades, technological advances allowed for the development of techniques and instrumentations that are increasingly being used in hydropeaking impact and mitigation assessments. This paper aims to provide a review, to researchers and managers interested in this field, of some of the most innovative methods and techniques, involving technology, that are available to study hydropeaking effects on downstream ecosystem, particularly from a fish perspective. We discuss the fundamentals behind such techniques, their advantages, and disadvantages, while also providing practical examples of their application and of the type of results that can be obtained. We finish by discussing some of the shortcomings of these methods and how related technology can evolve to solve current limitations.  相似文献   
608.
Cognition, Technology & Work - Contributing to the scarce literature on how companies can deal with their business model of digital transition, this work explores the digital transformation...  相似文献   
609.
The material properties of short fiber composites, such as modulus, strength and thermal expansion, are greatly dependent on the fiber orientation state in the composite. Although the orientation pattern is often quite complex, models that allow its prediction have been successfully applied in combination with micromechanical models to calculate moduli and thermal properties. This paper describes the derivation of a model to predict the strength of short fiber composites with arbitrary fiber orientation and fiber length distribution based on classical (micro-) mechanical theories. The predictions are in good agreement with data measured on short fiber composites with different fiber contents.  相似文献   
610.
Towpregs are a new class of pre-impregnated materials that can be used to obtain structural composites by compression molding. Consolidation is an important part of this process. In this work, a mathematical model was developed to predict the evolution of the compression pressure during the isothermal consolidation of thermoplastic matrix towpregs. The model relates the applied pressure to operational variables (speed and temperature) and material variables (viscosity, particle size, and polymer volume fraction). Tests were carried out at different temperatures and platen closing speeds, using carbon fiber-reinforced polycarbonate towpregs. The data obtained was compared with theoretical calculations, demonstrating the applicability of the model.  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