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   3151篇
  免费   219篇
  国内免费   4篇
电工技术   64篇
综合类   1篇
化学工业   811篇
金属工艺   43篇
机械仪表   73篇
建筑科学   152篇
矿业工程   1篇
能源动力   101篇
轻工业   244篇
水利工程   10篇
石油天然气   3篇
武器工业   1篇
无线电   297篇
一般工业技术   585篇
冶金工业   137篇
原子能技术   28篇
自动化技术   823篇
  2024年   5篇
  2023年   29篇
  2022年   91篇
  2021年   150篇
  2020年   76篇
  2019年   89篇
  2018年   99篇
  2017年   92篇
  2016年   144篇
  2015年   113篇
  2014年   147篇
  2013年   221篇
  2012年   202篇
  2011年   230篇
  2010年   194篇
  2009年   192篇
  2008年   179篇
  2007年   167篇
  2006年   120篇
  2005年   96篇
  2004年   118篇
  2003年   98篇
  2002年   64篇
  2001年   52篇
  2000年   43篇
  1999年   35篇
  1998年   28篇
  1997年   25篇
  1996年   35篇
  1995年   27篇
  1994年   26篇
  1993年   20篇
  1992年   21篇
  1991年   10篇
  1990年   7篇
  1989年   11篇
  1988年   5篇
  1987年   14篇
  1986年   7篇
  1985年   16篇
  1984年   17篇
  1983年   11篇
  1982年   8篇
  1981年   7篇
  1980年   4篇
  1979年   6篇
  1978年   4篇
  1977年   6篇
  1975年   3篇
  1973年   3篇
排序方式: 共有3374条查询结果,搜索用时 15 毫秒
141.
The purpose of this work was the preparation and characterization of polymeric membranes for the selective recognition of saccharides using molecular imprinting technology associated with phase inversion. A system able to bind saccharides with high selectivity is particularly important in the pharmaceutical sector, since some of these compounds are constituents of molecules which can exert serious toxic effects even at very low concentrations. Two polymeric matrices were prepared using poly(ethylene‐co‐vinyl alcohol) copolymers, with an ethylene molar content of 32% and 44%, and were imprinted with two different saccharide molecules: maltose and 2‐keto‐3‐deoxy‐d ‐manno‐octulosonate (KDO). Matrices imprinted against maltose and KDO showed an easy template extraction, high binding capability and satisfactory selectivity, particularly for the matrix with an ethylene molar content of 44%. © 2017 Society of Chemical Industry  相似文献   
142.
This paper presents a novel system for production of pure oxygen based on the integration of a solid oxide fuel cell (SOFC) and a solid oxide electrolyzer (SOEC). In the proposed arrangement, the SOFC provides electricity, heat and H2O in vapour phase to the SOEC which carries out the inverse reactions of the SOFC, that is the separation of H2O into H2 (used as a fuel for the SOFC) and O2 (representing the yield of the system). Simulations carried out in different operating conditions show that when the integrated SOFC–SOEC device runs at low current densities (less than 1000 A m−2), pure oxygen can be generated with an electric consumption comparable to mid-size cryogenic air separation units, and significantly lower than small scale systems based on the PSA technology.  相似文献   
143.
144.
145.
In this article, we reports the effects of the processing conditions on the morphological and hollow attributes of polystyrene micrometric hollow particles produced by the use of a recently developed technique based on the gas foaming of spherical, dense particles. By modulating the foaming temperature and saturation pressure, we produced hollow particles with different attributes in terms of hollow dimensions, eccentricity, and open–close features. The results from these small systems were compared, and we found agreement with what is typically observed in bulk polymeric foaming, for example, an increase in the foaming efficiency with saturation pressure and the nonmonotonic effect of temperature. Furthermore, we observed an increase in the hollow number when using nucleating agents with respect to the neat polymer and when using nitrogen with respect to carbon dioxide as the blowing agent. The effects of particle manipulation before foaming to achieve hollow elongated or distorted particles are also reported. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44236.  相似文献   
146.
The present paper deals with the synthesis of porous, sintered glass‐ceramics obtained at temperatures below 1150°C, originating from inorganic polymers based on fayalite slag. Firing led to the evaporation of water, dehydroxylation, and oxidation of Fe2+ above 345°C. For heating >700°C, the Si–O stretching band shifted from the 1160 and 750 cm?1 to the 1255 and 830 cm?1 region, due to a structural reorganization of the amorphous phase, whereas Fe–O bands appeared at 550 cm?1. The final microstructure consisted predominantly of an amorphous phase, hematite, and franklinite. The open porosity and compressive strength decreased and increased, respectively, as the firing temperature increased. The final values suggest properties comparable to that of structural lightweight concrete, still, the materials synthesized herein, are lighter, and made primarily from secondary resources.  相似文献   
147.
The direct ink writing of an ink composed of a preceramic polymer and fillers was used to produce hardystonite (Ca2ZnSi2O7) bioceramic scaffolds. Suitable formulations were developed for the extrusion of fine filaments (350 μm diameter) through a nozzle. The preceramic polymer was employed with the double purpose of contributing to the rheology of the ink by increasing its viscosity and of forming the hardystonite phase upon heat treatment by reacting with the fillers. A control of the rheology is essential when spanning features have to be produced, and therefore the main rheological characteristics of the inks were measured (flow curves, dynamic oscillation tests, viscosity recovery tests) and compared to models reported in the literature. Highly porous scaffolds (up to 80% total porosity) were produced and heat treated in air or in nitrogen atmosphere. The influence of the heat‐treatment atmosphere on the morphology, crystalline phase assemblage, and compressive strength of the scaffolds was investigated.  相似文献   
148.
Although the development of super‐resolution microscopy dates back to 1994, its applications have been primarily focused on visualizing cellular structures and targets, including proteins, DNA and sugars. We now report on a system that allows both monitoring of the localization of exogenous small molecules in live cells at low resolution and subsequent super‐resolution imaging by using stochastic optical reconstruction microscopy (STORM) on fixed cells. This represents a powerful new tool to understand the dynamics of subcellular trafficking associated with the mode and mechanism of action of exogenous small molecules.  相似文献   
149.
150.
Kidney transplant recipients frequently suffer from skin infections and malignancies, possibly due to the effects of long-term immunosuppressive therapy. While the relationships between immunosuppression and these pathological conditions have been widely investigated, little is known about the relative incidence and characteristics of inflammatory skin diseases in this type of patient. In this study, we analyze the incidence of a number of inflammatory cutaneous diseases in a cohort of patients who underwent kidney transplantation. Although our study shows a relatively low incidence of these pathologies in transplanted patients—in agreement with the general action of immunosuppressant therapies in reducing inflammation—we scored a different efficacy of the various immunosuppressive regimens on inflammatory and autoimmune skin diseases. This information can be key for designing immunosuppressive regimens and devising accurate follow-up protocols.  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