全文获取类型
收费全文 | 249篇 |
免费 | 16篇 |
专业分类
化学工业 | 81篇 |
金属工艺 | 3篇 |
机械仪表 | 1篇 |
建筑科学 | 2篇 |
能源动力 | 18篇 |
轻工业 | 47篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 16篇 |
一般工业技术 | 66篇 |
冶金工业 | 5篇 |
原子能技术 | 3篇 |
自动化技术 | 19篇 |
出版年
2023年 | 15篇 |
2022年 | 23篇 |
2021年 | 18篇 |
2020年 | 14篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 14篇 |
2014年 | 11篇 |
2013年 | 17篇 |
2012年 | 9篇 |
2011年 | 10篇 |
2010年 | 5篇 |
2009年 | 12篇 |
2008年 | 14篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有265条查询结果,搜索用时 15 毫秒
181.
182.
4-chloroisonitroacetophenone 4-aminobenzylhydrazone (CAAH) chemically anchored on a silica gel surface, has been used for Cu(II) sorption from aqueous solution. The surface modification processes was performed after silanization of silica, then analyzed by elemental analysis, infrared spectroscopy, and thermogravimetry. The sorption behavior of copper(II) was evaluated by the use of batch and column methods. The influences of the concentration, temperature and pH for sorption on the immobilized silica gel with Schiff base were investigated. The obtained dynamic data were fitted to Freundlich, Langmuir and Dubinin-Raduskevich (D-R) isotherms. The mean sorption energy (E) of copper sorption onto silica gel was calculated from D-R isotherm indicating a chemical ion-exchange. The thermodynamic parameters such as Gibbs free energy change, enthalpy change and entropy change were calculated from the adsorption isotherms which were used to explain the mechanism of the adsorption. 相似文献
183.
Hilal Köse 《Electrochimica acta》2009,54(6):1680-5089
Bi2Te3−ySey thin films were grown on Au(1 1 1) substrates using an electrochemical co-deposition method at 25 °C. The appropriate co-deposition potentials based on the underpotential deposition (upd) potentials of Bi, Te and Se have been determined by the cyclic voltammetric studies. The films were grown from an electrolyte of 2.5 mM Bi(NO3)3, 2 mM TeO2, and 0.3 mM SeO2 in 0.1 M HNO3 at a potential of −0.02 V vs. Ag|AgCl (3 M NaCl). X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were employed to characterize the thin films. XRD and EDS results revealed that the films are single phase with approximate composition of Bi2Te2.7Se0.3. SEM studies showed that the films are homogeneous and have micronsized granular crystallites. 相似文献
184.
185.
When a metal matrix composite undergoes centrifugal casting, the velocity, deceleration, displacement, and segregation of
its particles are modeled according to changes in the centrifugal radius, as well as by variations in the molten metal viscosity
as the temperature decreases during the cooling process. A cast aluminum alloy A356 reinforced by 10 V% of silicon carbide
particles (SiC), with a median diameter of 12 μm, was used to conduct the experiments, and a mathematical modeling showed
that the particles’ volume fraction on the outer casting face varied according to whether the viscosity of the liquid metal
used was constant or variable. If variations in viscosity during the cooling process are taken into account, then the volume
fraction of the particles for a given time of centrifugation changes on the outer casting face, while it increases if the
viscosity was constant. Modeling the particle segregation with variable viscosity produces results that are closer to those
obtained with experiments than is the case when a constant viscosity is used. In fact, the higher the initial pouring and
mold temperatures, the higher the effect of the viscosity variation on particle segregation. 相似文献
186.
The diagnosis and follow-up of 20 cases of intracranial abscess are analyzed, with particular attention to the role of computed tomography (CT). the differential diagnosis of the CT appearance is presented, and the value of clinical and laboratory findings is discussed. Of special interest is the potential effect of steroids on CT findings as well as the frequent observation of a residual enhancing focus seen on the scan obtained at hospital discharge. 相似文献
187.
188.
The development of Nuclear Magnetic Resonance (NMR) imaging has brought together the experimental techniques of NMR spectroscopy and image processing with the consequence that new experimental requirements and apparatus are currently being developed. Examples of these requirements include the large amounts of data which can be generated and the effect on data processing and storage requirements. Also, the increased size of objects under investigation necessitate some major changes in the magnet and r.f. system. A discussion of these specific requirements is presented together with an overview of all components of the NMR imaging system. 相似文献
189.
Composite microfiltration membranes covered with a thin layer of molecularly imprinted polymer (MIP) selective to adenosine 3′:5′‐cyclic monophosphate (cAMP) were obtained and their separation properties were studied. MIP layers were prepared using photoinitiated copolymerization of dimethylaminoethyl methacrylate (DMAEM) as a functional monomer and trimethylopropane trimethacrylate (TRIM) as a crosslinker in the presence of cAMP as template in ethanol/water mixture. Blank membranes were prepared under the same conditions, but without cAMP. It was found out that pH of aqueous solution of the template has an effect on the binding of cAMP with MIP membranes. It was concluded that the ability of MIP membranes to bind cAMP is a result of both ionic interactions between charged dimethylamino groups of polymer matrix and the phosphorous residue of cAMP molecule and the specific shape of recognizing sites. These sites are complementary to cAMP in terms of three dimensional shape as well as correct position of functional groups involved in the template binding. This paper shows that the binding capability of MIP membranes can be adjusted by varying the values of degree of modification (DM). Atomic Force Microscopy (AFM) and Scanning Force Microscopy (SEM) were used to visualise surfaces and cross sections of membranes to gain better understanding in the analysis of MIP layer deposited on membranes. 相似文献
190.
The recovery of a normal zone produced in a superconducting magnet following a mechanical disturbance depends on the heat transfer rate to the liquid helium cooling channels. One of the factors which affects the heat transfer to the channel is the amount of vapor accumulated in the channel during and following a disturbance. The present work is undertaken to determine the void fraction in a liquid helium channel and to study the effect of the amount of vapor in the channel on the heat transfer characteristics. Heat pulses of 30 to 300 ms duration are introduced into the simulated conductor, and observations are made of the resulting temperature response and of the vapor fraction in the channel. The vapor fraction is determined by means of a capacitance bridge which responds to the small difference in dielectric constant between liquid and vapor helium. For completeness steady state measurements of temperature and vapor fraction are also reported. 相似文献