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   667篇
  免费   26篇
  国内免费   1篇
电工技术   8篇
化学工业   252篇
金属工艺   26篇
机械仪表   18篇
建筑科学   37篇
矿业工程   5篇
能源动力   19篇
轻工业   51篇
水利工程   8篇
石油天然气   2篇
无线电   27篇
一般工业技术   114篇
冶金工业   30篇
原子能技术   7篇
自动化技术   90篇
  2022年   24篇
  2021年   32篇
  2020年   9篇
  2019年   5篇
  2018年   19篇
  2017年   23篇
  2016年   24篇
  2015年   13篇
  2014年   29篇
  2013年   57篇
  2012年   24篇
  2011年   43篇
  2010年   19篇
  2009年   46篇
  2008年   26篇
  2007年   27篇
  2006年   18篇
  2005年   20篇
  2004年   16篇
  2003年   20篇
  2002年   12篇
  2001年   15篇
  2000年   10篇
  1998年   2篇
  1997年   4篇
  1996年   7篇
  1995年   5篇
  1994年   7篇
  1993年   4篇
  1992年   7篇
  1991年   2篇
  1990年   5篇
  1989年   5篇
  1988年   7篇
  1987年   9篇
  1986年   6篇
  1985年   9篇
  1984年   11篇
  1983年   11篇
  1982年   9篇
  1981年   9篇
  1980年   9篇
  1979年   6篇
  1977年   3篇
  1976年   6篇
  1975年   2篇
  1974年   4篇
  1973年   3篇
  1970年   2篇
  1956年   2篇
排序方式: 共有694条查询结果,搜索用时 15 毫秒
61.
This paper presents methods for improving the quality of IR images that significantly facilitate the detection of physical and structural non-uniformities in layered objects. The methods are based on wavelets transformations. Both, discrete and continuous wavelet transforms were used. The space-scale representation of thermal image are used for the detection thermal non-uniformities in the objects examined. Examples of recorded and improved images are presented in this paper.  相似文献   
62.
Efficient monitoring of mine groundwater conducted with a standard methodology makes the evaluation of the influence of mine water on the environment easier. The paper examines problems of monitoring and proposes a groundwater monitoring system for existing and flooded abandoned mines. The final effect of mine waters monitoring enables ecochemical and economical evaluation. It also makes it possible to select and use the appropriate proecological technologies for mine waters.  相似文献   
63.
Conventional precipitation methods of industrial sewage and wastewater purification are not very effective and are insufficient in many cases. This implies the necessity of searching new, effective methods exploiting cheap, accessible and ecologically safe ion exchangers and sorbents. The paper presents the studies on removal of heavy metal ions — Cu(II), Zn(II), Co(II), Ni(II) and Fe(III) — from aqueous solutions in the presence of EDTA carried out on commercially available, strongly basic monodisperse anion exchangers with the polystyrene skeleton gel, Lewatit MonoPlus M 500; and the macroporous, Lewatit MonoPlus MP 500, which are more widely applied in water purification processes. The research results indicate a high affinity of the Lewatit MonoPlus M 500 and Lewatit MonoPlus MP 500 anion exchangers in the chloride form for copper(II), nickel(II), cobalt(II) and zinc(II) complexes with EDTA. The affinity series for the heavy metal complexes in the 0.001 M M(II)/(III)–0.001 M EDTA and 0.001 M M(II)/(III)–0.001M EDTA–0.001 M–0.002 M NaOH systems were found for the Lewatit MonoPlus M 500 anion exchanger in the chloride form to be as follows: Cu(II) > Ni(II) > Co(II) > Zn(II) Fe(III). In the case of the Lewatit MonoPlus MP 500 anion exchanger in the chloride form there was found the following affinity series: Cu(II) > Co(II) > Ni(II) > Zn(II) Fe(III). These anion exchangers can be applied in the removal of copper(II) complexes from waters and wastewaters.  相似文献   
64.
In this paper the embedding of gold clusters in crystallizing bisphenol-A polycarbonate is treated as diffusion with drift in inhomogeneous and changing in time medium. Initially the gold is deposited on the polymer surface, which is subsequently exposed to acetone vapour. The polymer undergoes significant crystallization, induced by diffusing agent, while gold clusters become embedded in its bulk. The paper presents a model of gold dispersion based on Smoluchowski equation. It identifies the driving force of dispersion with the gradient of stress field generated during crystallization. Numerical results of the model are found to be in good agreement with available experimental data obtained by XPS depth profiling technique.  相似文献   
65.
In this paper we propose a new optimality measure for Wireless Sensor Network-based structural monitoring systems. First, we present the results of experiments showing the reasons for random effects in Wireless Sensor Network (WSN) functioning. Then, the formulas for calculating a network’s reputation measure are given. Finally, we conclude with arguments for the application of the reputation-based optimality measure in WSNs. We propose significantly new recommendations for the design and usage of WSNs.  相似文献   
66.
The adsorption kinetics of the SARS-CoV-2 spike protein subunit with the receptor binding domain at abiotic surfaces was investigated. A combination of sensitive methods was used such as atomic force microscopy yielding a molecular resolution, a quartz microbalance, and optical waveguide lightmode spectroscopy. The two latter methods yielded in situ information about the protein adsorption kinetics under flow conditions. It was established that at pH 3.5–4 the protein adsorbed on mica and silica surfaces in the form of compact quasi-spherical aggregates with an average size of 14 nm. The maximum coverage of the layers was equal to 3 and 1 mg m−2 at pH 4 and 7.4, respectively. The experimental data were successfully interpreted in terms of theoretical results derived from modeling. The experiments performed for flat substrates were complemented by investigations of the protein corona formation at polymer particles carried out using in situ laser Doppler velocimetry technique. In this way, the zeta potential of the protein layers was acquired as a function of the coverage. Applying the electrokinetic model, these primary data were converted to the dependence of the subunit zeta potential on pH. It was shown that a complete acid-base characteristic of the layer can be acquired only using nanomolar quantities of the protein.  相似文献   
67.
Deformation method for centrically compressed thin‐walled bars with mono‐ and bisymmetrical open cross‐sections. In correspondence with the classic deformation method of warping torsion for thin‐walled bars [1], that method has been moved into the field of column stability. For the single cross‐sectional symmetry, the general solution of the fundamental system of equations has been found and its particular shapes for three basic kinds of column support presented. Thereby, the formulas or the boundary simplified for analysis of the bimoments have been settled. These relations have been simplified for the double cross‐sectional symmetry. An analysis of a bisymmetrical cross‐section has lead to the determination of the necessary boundary forces for the three kinds of column support considered. It has been shown that all the relations for torsion are similar to those for bending. A proposal for the calculations of the critical loads of torsional buckling in continuous columns has been formulated and a relevant numerical example given. The paper calls special attention to the related merits of Professor Kurt Klöppel , a graduate of the former Technischen Hochschule Danzig. Actually, already 100 years have passed since the foundation of TH Danzig. It is also the predecessor of the contemporary Politechnika Gdańska, with which the author is being connected since 1949.  相似文献   
68.
An algorithm for the spectrum of the rotational component of surface ground motion during earthquake is derived. To obtain the rotation the total motion is decomposed into the wave components. Then the rotational motion is obtained in terms of the horizontal and vertical components treated as non-stationary random processes. The evolutionary spectrum of the rotational acceleration is a function of respective translational spectra, their co-spectrum and respective wave parameters. The analysis shows a shift of the higher frequency components in the rotational spectrum. The rotation is a function of the time derivative of translational components.  相似文献   
69.
The sorption of Tartrazine, Allura Red, Sunset Yellow and Indigo Carmine from aqueous solutions onto the strongly basic anion-exchanger (Lewatit MonoPlus M-600) of dimethylethanolamine functional groups and styrene–divinylbenzene matrix was investigated. The experimental data obtained at 50, 100, 200, 300 and 500 mg/dm3 initial concentrations at 20 °C were applied to the pseudo-first order, pseudo-second order and Weber–Morris kinetic models. The calculated sorption capacities (q1,cal) and the rate constant of the first-order adsorption (k1) were determined. The pseudo-second order kinetic constants (k2) and capacities (q2,cal) were calculated from the plots of t/qt vs. t, 1/qt vs. 1/t, 1/t vs. 1/qt, qt/t vs. qt and 1/q2 − qt vs. t for type 1, type 2, type 3, type 4 and type 5 of the pseudo-second order expression, respectively.  相似文献   
70.
Application Layer Traffic Optimization (ALTO) has recently gained attention in the research and standardisation community as a way for a network operator to guide the peer selection process of distributed applications by providing network layer topology information. In particular P2P applications are expected to gain from ALTO, due to the many connections peers form among each other, often without taking network layer topology information into account. In this paper, we present results of an extensive intra-ISP trial with an ALTO-enhanced P2P filesharing software. In summary, our results show that—depending on the concrete setting and on the distribution of upload capacity in the network—ALTO enables an ISP to save operational costs significantly while not degrading application layer performance noticeably. In addition, based on our experience we are able to give advice to operators on how to save costs with ALTO while not sacrificing application layer performance at all.  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