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   3399篇
  免费   54篇
  国内免费   2篇
电工技术   57篇
综合类   1篇
化学工业   641篇
金属工艺   239篇
机械仪表   192篇
建筑科学   53篇
矿业工程   60篇
能源动力   59篇
轻工业   103篇
水利工程   38篇
石油天然气   132篇
无线电   239篇
一般工业技术   903篇
冶金工业   377篇
原子能技术   160篇
自动化技术   201篇
  2022年   58篇
  2021年   74篇
  2020年   50篇
  2019年   45篇
  2018年   86篇
  2017年   103篇
  2016年   121篇
  2015年   68篇
  2014年   91篇
  2013年   113篇
  2012年   117篇
  2011年   129篇
  2010年   108篇
  2009年   122篇
  2008年   115篇
  2007年   112篇
  2006年   87篇
  2005年   81篇
  2004年   66篇
  2003年   70篇
  2002年   88篇
  2001年   59篇
  2000年   59篇
  1999年   49篇
  1998年   53篇
  1997年   66篇
  1996年   33篇
  1995年   39篇
  1993年   38篇
  1992年   32篇
  1991年   40篇
  1990年   38篇
  1989年   44篇
  1988年   39篇
  1986年   34篇
  1985年   34篇
  1984年   35篇
  1983年   40篇
  1982年   32篇
  1980年   32篇
  1978年   43篇
  1977年   55篇
  1976年   47篇
  1975年   40篇
  1974年   46篇
  1973年   49篇
  1972年   38篇
  1971年   46篇
  1969年   40篇
  1967年   32篇
排序方式: 共有3455条查询结果,搜索用时 15 毫秒
81.
82.
A specific analog device (spin echo processor) is proposed for processing of pulsed data in functional electronic devices under certain conditions. It is shown that a disadvantage of such devices related to generation of multiple noise signals upon processing of multipulse trains can be eliminated with the aid of magnetically ordered working substance using an additional channel that forms magnetic field in the working substance.  相似文献   
83.
The development of multifunctional nanoscale systems that can mediate efficient tumor targeting, together with high cellular internalization, is crucial for the diagnosis of glioma. The combination of imaging agents into one platform provides dual imaging and allows further surface modification with targeting ligands for specific glioma detection. Herein, transferrin (Tf)-decorated niosomes with integrated magnetic iron oxide nanoparticles (MIONs) and quantum dots (QDs) were formulated (PEGNIO/QDs/MIONs/Tf) for efficient imaging of glioma, supported by magnetic and active targeting. Transmission electron microscopy confirmed the complete co-encapsulation of MIONs and QDs in the niosomes. Flow cytometry analysis demonstrated enhanced cellular uptake of the niosomal formulation by glioma cells. In vitro imaging studies showed that PEGNIO/QDs/MIONs/Tf produces an obvious negative-contrast enhancement effect on glioma cells by magnetic resonance imaging (MRI) and also improved fluorescence intensity under fluorescence microscopy. This novel platform represents the first niosome-based system which combines magnetic nanoparticles and QDs, and has application potential in dual-targeted imaging of glioma.  相似文献   
84.
A new approach to the synthesis of silicate glass with cadmium sulfide (CdS) nanoparticles has been developed. It has been demonstrated that replacement of cadmium sulfide with cadmium oxide and zinc sulfide used as sources of cadmium and sulfur allows a substantial reduction of sulfur volatilization during the melting. The produced samples have been investigated by the methods of spectrophotometry in the ultraviolet and visible ranges of the optical range. Thermal treatment of the samples at temperatures exceeding the glass formation point initiates the growth of CdS nanoparticles, which results in the increase of their average size from 3 to 5.2 nm and a significant shift of the fundamental absorption edge to the longer wavelength range from 380 to 480 nm.  相似文献   
85.
Methods used for enhancing heat transfer in power installations and industrial thermal engineering apparatuses are reviewed. Classification of these methods is given, and the corresponding types of intensifiers are considered.  相似文献   
86.
The paper presents an analysis of effective potentials of Dirac equations in Schwarzschild and Reissner–Nordström fields. It is shown that in the majority of the explored cases the condition of a particle “fall” to the corresponding event horizons is fulfilled. An exception is one of the solutions with a normalizable wave functions for the Reissner–Nordström extreme field, for which the existence of a stationary bound state of a half-spin particles is possible inside the event horizon.  相似文献   
87.
Errors in determining coal quality are compared. For the example of the ash content, it is shown that the error in forming the samples is almost an order of magnitude greater than the error in sample analysis. The metrological characteristics and conditions of correct utilization of results from coal analysis are considered in the light of GOST R ISO 5725 standards. The correct comparison of results obtained by different methods is described.  相似文献   
88.
89.
The contribution of this study is an increased understanding of personal creativity and the innovation process in haute cuisine, a validation of the socio‐cultural systems view of creativity and a model that accounts for the socio‐cultural dimensions of haute cuisine. In this paper we discuss existing views that conceptualize creativity and innovation in this sector as a sequential developmental process following the principles of operations management. However, based on in‐depth interviews with world‐renowned chefs, we argue for a systemic rather than sequential developmental process view. The reason for this is that the chefs interviewed understand the ‘creativity part’ of the innovation process as an embodied experience often guided by intuition and the ‘innovation part’ as a process of social evaluation greatly dependent on the perception, knowledge and value judgement of the testers from the leading restaurant guides. The main implications of the findings go beyond the haute cuisine sector and open areas for future research on creativity and intuition more generally.  相似文献   
90.
A highly active and stable catalyst/support system is developed by using a two-step process. In the first step, activated carbon composite support (ACCS) is synthesized that retains its activity after accelerated stress test (AST). A 30% Pt/ACCS catalyst shows no loss of mass activity and power density after 5000 cycles at 1.0–1.5 V while the commercial Pt/C and Pt/290G catalysts show drastic mass activity losses (57.5% and 66.2%, respectively) and power density losses (88.7% and 84.0%, respectively). In the second step, Pt catalyst with a compressive Pt lattice (Pt1) is synthesized through a USC-developed annealing procedure in which Co atoms previously embedded in the support diffuse into Pt. The 30% Pt1/ACCS shows high initial power density (rated) of 0.174 gPt kW?1 and high stability of 24 mV loss at 0.8 A cm?2 with an electrochemical active surface area (ECSA) loss of 42% after 30,000 cycles (0.6–1.0 V). The support stability under 1.0–1.5 V potential cycling shows potential loss of 8 mV at 1.5 A cm?2 and ECSA loss of 22% after 5000 cycles. Improved stability and activity of Pt*/ACCS catalyst are due to synergistic effect of catalytic activity and stability of ACCS and formation of compressive Pt lattice catalyst.  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