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   3245篇
  免费   113篇
  国内免费   2篇
电工技术   34篇
综合类   6篇
化学工业   710篇
金属工艺   90篇
机械仪表   67篇
建筑科学   62篇
矿业工程   25篇
能源动力   46篇
轻工业   186篇
水利工程   18篇
石油天然气   81篇
无线电   225篇
一般工业技术   742篇
冶金工业   599篇
原子能技术   74篇
自动化技术   395篇
  2023年   22篇
  2022年   87篇
  2021年   125篇
  2020年   61篇
  2019年   77篇
  2018年   89篇
  2017年   63篇
  2016年   100篇
  2015年   57篇
  2014年   109篇
  2013年   163篇
  2012年   127篇
  2011年   152篇
  2010年   132篇
  2009年   130篇
  2008年   126篇
  2007年   103篇
  2006年   122篇
  2005年   88篇
  2004年   68篇
  2003年   74篇
  2002年   57篇
  2001年   36篇
  2000年   27篇
  1999年   45篇
  1998年   123篇
  1997年   95篇
  1996年   62篇
  1995年   39篇
  1994年   46篇
  1993年   56篇
  1992年   30篇
  1991年   20篇
  1990年   21篇
  1989年   27篇
  1988年   23篇
  1987年   38篇
  1986年   31篇
  1985年   33篇
  1984年   24篇
  1983年   29篇
  1982年   30篇
  1980年   22篇
  1979年   20篇
  1978年   22篇
  1977年   42篇
  1976年   53篇
  1970年   19篇
  1969年   21篇
  1968年   19篇
排序方式: 共有3360条查询结果,搜索用时 171 毫秒
91.
The current approaches to the optimization of systems under uncertainty are considered. An exact formulation of the problem of the conditional optimization of the target function parameters and limitations under interval uncertainty is given. A determinization method allowed us to solve the problem by reducing it to two completely determined ones of conditional optimization of the same type is stated and proved.  相似文献   
92.
93.
94.
95.
Metallurgical and Materials Transactions B - We develop a method for generation of a single gas bubble in a pool of molten metal. The method can be useful for applications and research studies...  相似文献   
96.
97.
98.
Effect of ternary solute interaction on interfacial segregation and grain boundary embrittlement in an MIJ system is modeled on the basis of combined Guttmann and Rice–Wang approaches. It is clearly shown that repulsive IJ interaction strengthens interfacial segregation of the impurity I, suppresses segregation of the solute J, and substantially enhances intergranular embrittlement. Attractive interaction exhibits an opposite effect. Generally, the effect of the ternary interaction is weaker than that of the binary one. Although there are only rare experimental data in this respect, their comparison to model calculations shows a very good agreement.  相似文献   
99.
Tungsten mono-carbide (WC) nanoparticles supported on multiwalled carbon nanotube (MWCNT) was synthesized by a microwave-assisted solid-state carburization. The prepared samples were used as a co-catalyst to prepare Pt-WC/MWCNT catalyst for a proton-exchange membrane fuel cell. MWCNTs with and without oxidative pretreatments were characterized as the starting precursors. The influence of the carbide formation conditions on the physicochemical characteristics of the final product were extensively investigated. According to the results, surface pretreatment of the MWCNTs can improve the yield of carbide formation. Furthermore, carburization process can improve the catalyst utilization due to increasing the number of surface defects of the MWCNT supporting materials which can be interpreted as structural effect of the carburization process. It is believed that the superior performance of electrodes modified with tungsten carbide is mostly due to the structural effect of the carburization process and synergistic effect between the electrocatalytic activity of WC and Pt.  相似文献   
100.
A fundamental assumption of today''s molecular genetics paradigm is that complex morphology emerges from the combined activity of low-level processes involving proteins and nucleic acids. An inherent characteristic of such nonlinear encodings is the difficulty of creating the genetic and epigenetic information that will produce a given self-assembling complex morphology. This ‘inverse problem’ is vital not only for understanding the evolution, development and regeneration of bodyplans, but also for synthetic biology efforts that seek to engineer biological shapes. Importantly, the regenerative mechanisms in deer antlers, planarian worms and fiddler crabs can solve an inverse problem: their target morphology can be altered specifically and stably by injuries in particular locations. Here, we discuss the class of models that use pre-specified morphological goal states and propose the existence of a linear encoding of the target morphology, making the inverse problem easy for these organisms to solve. Indeed, many model organisms such as Drosophila, hydra and Xenopus also develop according to nonlinear encodings producing linear encodings of their final morphologies. We propose the development of testable models of regeneration regulation that combine emergence with a top-down specification of shape by linear encodings of target morphology, driving transformative applications in biomedicine and synthetic bioengineering.  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