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   1394篇
  免费   72篇
  国内免费   4篇
电工技术   15篇
综合类   1篇
化学工业   357篇
金属工艺   25篇
机械仪表   19篇
建筑科学   52篇
矿业工程   12篇
能源动力   47篇
轻工业   79篇
水利工程   8篇
石油天然气   12篇
无线电   104篇
一般工业技术   380篇
冶金工业   84篇
原子能技术   28篇
自动化技术   247篇
  2024年   2篇
  2023年   18篇
  2022年   38篇
  2021年   51篇
  2020年   34篇
  2019年   36篇
  2018年   35篇
  2017年   50篇
  2016年   39篇
  2015年   47篇
  2014年   63篇
  2013年   117篇
  2012年   88篇
  2011年   109篇
  2010年   68篇
  2009年   53篇
  2008年   88篇
  2007年   77篇
  2006年   58篇
  2005年   56篇
  2004年   37篇
  2003年   49篇
  2002年   43篇
  2001年   18篇
  2000年   13篇
  1999年   13篇
  1998年   13篇
  1997年   18篇
  1996年   14篇
  1995年   9篇
  1994年   13篇
  1993年   13篇
  1992年   7篇
  1991年   7篇
  1990年   5篇
  1989年   11篇
  1987年   3篇
  1986年   3篇
  1985年   2篇
  1984年   6篇
  1983年   7篇
  1982年   5篇
  1981年   2篇
  1980年   3篇
  1979年   7篇
  1976年   3篇
  1971年   5篇
  1969年   2篇
  1955年   1篇
  1954年   1篇
排序方式: 共有1470条查询结果,搜索用时 15 毫秒
91.
Enabling the lithium metal anode (LMA) in solid-state batteries (SSBs) is the key to developing high energy density battery technologies. However, maintaining a stable electrode–electrolyte interface presents a critical challenge to high cycling rate and prolonged cycle life. One such issue is the interfacial pore formation in LMA during stripping. To overcome this, either higher stack pressure or binary lithium alloy anodes are used. Herein, it is shown that fine-grained (d = 20 µm) polycrystalline LMA can avoid pore formation by exploiting the microstructural dependence of the creep rates. In a symmetric cell set-up, i.e., LiǀLi6.25Al0.25La3Zr2O12(LLZO)ǀLi, fine-grained LMA achieves > 11.0 mAh cm−2 compared to ≈ 3.6 mAh cm−2 for coarse-grained LMA (d = 295 µm) at 0.1 mA cm−2 and at moderate stress of 2.0 MPa. Smaller diffusion lengths (≈ 20 µm) and higher diffusivity pathway along dislocations (Dd ≈ 10−7 cm2 s−1), generated during cell fabrication, result in enhanced viscoplastic deformation in fine-grained polycrystalline LMA. The electrochemical performances corroborate well with estimated creep rates. Thus, microstructural control of LMA can significantly reduce the required stack pressure during stripping. These results are particularly relevant for “anode-free” SSBs wherein both the microstructure and the mechanical state of the lithium are critical parameters.  相似文献   
92.
93.
Direct injection of samples on high-resolving mass spectrometers is an effective way to maximize analytical throughput and yet allow analyte discrimination in complex samples by mass-to-charge ratio. We present a platform of flow injection electrospray-time-of-flight mass spectrometry to profile small molecules in >1400 biological extracts per day at native mass resolution. We comprehensively benchmark the performance with more than 5000 injections of chemically defined standards and Escherichia coli cellular extracts obtained from miniscale cultivations. For at least 90% of tested compounds, we attain a linear response over 3 decades of concentration, interday coefficient of variation of <20%, and a mass accuracy of <0.001 amu. In polar Escherichia coli fractions, we reproducibly detected >1500 distinct ions in each mode. The accurate mass and correlation analysis enabled one to assign with good confidence 400-800 ions to electrospray derivatives of metabolites listed in the genome-wide reconstruction of Escherichia coli metabolism. Hence, we attain a coverage of about one-quarter of the total number of compounds listed in the reconstruction. Finally, we present an exemplary screen with Escherichia coli deletion mutants to show the exquisite capacity of the platform to identify lesions in primary metabolism at high throughputs.  相似文献   
94.
A suffix tree approach to anti-spam email filtering   总被引:1,自引:0,他引:1  
We present an approach to email filtering based on the suffix tree data structure. A method for the scoring of emails using the suffix tree is developed and a number of scoring and score normalisation functions are tested. Our results show that the character level representation of emails and classes facilitated by the suffix tree can significantly improve classification accuracy when compared with the currently popular methods, such as naive Bayes. We believe the method can be extended to the classification of documents in other domains. Editor: Tom Fawcett  相似文献   
95.
This paper analyses the load influence on a d.c. drive motor servo system for all six degrees of freedom of industrial robots with an articulated configuration. Through the analyses, the analytical equations of total inertia and gravitation moments of an industrial robot servo system for external coordinate function were obtained. A mathematical model of an electro-mechanical industrial robot system was also developed.  相似文献   
96.
The adhesion of spheroidal particles to spherical drops is calculated and discussed in terms of an equilibrium-penetration index. The present study emphasizes the case of particles that are sufficiently large to affect the drop volume upon penetration. It is shown that the more elongated the particles, the steeper the dependence of the penetration index on the contact angle. The effect of line tension on nanoscale particles is considered. Positive line tensions increase the steepness of the dependence of penetration index on contact angle whereas negative line tensions decrease this dependence. In addition, the energy barrier caused by positive line tensions is presented and discussed.  相似文献   
97.
Incorporation of cleavable linkers into peptides and proteins is of particular value in the study of biological processes. Here we describe the synthesis of a cleavable linker that is hypersensitive to oxidative cleavage as the result of the periodate reactivity of a vicinal amino alcohol moiety. Two strategies directed towards the synthesis of a building block suitable for solid‐phase peptide synthesis were developed: a chemoenzymatic route, involving L ‐threonine aldolase, and an enantioselective chemical route; these led to α,γ‐diamino‐β‐hydroxybutanoic acids in diastereoisomerically mixed and enantiopure forms, respectively. Incorporation of the 1,2‐amino alcohol linker into the backbone of a peptide generated a conditional peptide that was rapidly cleaved at very low concentrations of sodium periodate. This cleavable peptide ligand was applied in the generation of MHC exchange reagents for the detection of antigen‐specific T cells in peripheral blood cells. The extremely low concentration of periodate required to trigger MHC peptide exchange allowed the co‐oxidation of methionine and disulfide residues to be avoided. Conditional MHC reagents hypersensitive to periodate can now be applied without limitations when UV irradiation is undesired or less practical.  相似文献   
98.
Increasing Productivity through Integrated Production Engineering and Processing Expertise The future of production engineering is interdisciplinary. Between product innovation and product marketing there lies a design process which has to be optimised and which is interdisciplinary in character. The design process has to satisfy the demands of global markets on chemical products, which lead, for example, to shorter and shorter product life cycles, and to demands for low production costs, high and consistent product quality, and faster market launches.  相似文献   
99.
100.
New efficient intermetallide catalysts for hydrogen storage in reversible processes of aromatics hydrogenation and naphthene dehydrogenation were studied. These catalysts provide an enhanced activity in the dehydrogenation of saturated organic molecules, with no side reactions like cracking, hydrogenolysis, ring opening, or coke formation occurring on these catalysts. The use of intermetallides provides some hydrogen storage capacity in the low-temperature region, while their catalytic activity in the dehydrogenation affords the hydrogen supply in the high-temperature range.  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