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   1100篇
  免费   51篇
  国内免费   2篇
电工技术   32篇
综合类   8篇
化学工业   323篇
金属工艺   13篇
机械仪表   29篇
建筑科学   61篇
矿业工程   6篇
能源动力   21篇
轻工业   99篇
水利工程   6篇
无线电   99篇
一般工业技术   165篇
冶金工业   72篇
原子能技术   5篇
自动化技术   214篇
  2023年   16篇
  2022年   16篇
  2021年   28篇
  2020年   24篇
  2019年   27篇
  2018年   28篇
  2017年   21篇
  2016年   29篇
  2015年   40篇
  2014年   37篇
  2013年   50篇
  2012年   62篇
  2011年   72篇
  2010年   65篇
  2009年   54篇
  2008年   59篇
  2007年   52篇
  2006年   59篇
  2005年   41篇
  2004年   29篇
  2003年   23篇
  2002年   32篇
  2001年   18篇
  2000年   21篇
  1999年   18篇
  1998年   21篇
  1997年   28篇
  1996年   16篇
  1995年   24篇
  1994年   21篇
  1993年   17篇
  1992年   12篇
  1991年   10篇
  1990年   6篇
  1989年   10篇
  1988年   5篇
  1987年   4篇
  1985年   5篇
  1984年   3篇
  1983年   6篇
  1982年   5篇
  1981年   7篇
  1979年   4篇
  1978年   2篇
  1977年   4篇
  1976年   3篇
  1975年   2篇
  1974年   3篇
  1972年   2篇
  1969年   2篇
排序方式: 共有1153条查询结果,搜索用时 15 毫秒
91.
92.
The article presents results of an internet research on product-service systems. Web sites showing interesting practical examples and studies available online are presented to point out the practical relevance of innovative combinations of products and services. The multiplicity of research projects found on the internet shows that this phenomenon is also discussed intensively in research. These projects have been categorized by analyzing their web sites. Furthermore, the results of the internet research highlight a high diversity of terms for describing the concept of product-service systems. As a consequence, orientation in this subject area is hindered.  相似文献   
93.
The structure and biological activities of two disulphide isomersof a C-region deletion mutant of insulin-like growth factor-I(IGF-I) which has an Asn–Gly link engineered at the junctionof the A- and B-regions were studied before and after chemicalcleavage. Circular dichroism (CD) spectra and binding affinityto IGF binding protein 3 (IGFBP3) indicated that the treatmentwith hydroxylamine did not disrupt the overall tertiary foldof the hormones. Cleavage restored some binding affinity forthe IGF-I receptor in both isomers and weakly restored the abilityto stimulate incorporation of tritiated thymidine into DNA inNIH 3T3 fibroblasts transfected with the human IGF-I receptor.Cleavage also restored metabolic capacity, as measured by theability of the isomers to promote lipogenesis in isolated ratadipocytes through the insulin receptor. These results are consistentwith the theory that binding of IGF-I to the IGF-I receptorrequires a conformational change similar to that involved ininsulin binding the insulin receptor. The weak affinity forthe IGF-I receptor after cleavage is consistent with the beliefthat residues in the C-region interact with the IGF-I receptor.This structural difference between insulin and IGF-I gives eacha higher binding affinity for its own receptor.  相似文献   
94.
Prospects of plasma medicine: Applications of Tissue Tolerable Plasmas (TTP) Based on the current knowledge on the physical properties and biological effects of tissue tolerable plasma (ttp) potential perspectives of plasma medicine are discussed. Currently, the foundations for the following medical applications of ttp are developed by an interdisciplinary research team: Prevention and/or treatment of diseases such as chronic wounds, skin and mucosal infectious diseases, localized tumors, promotion of angiogenesis, and tissue ablation Inhibition and/or elimination of biofilms by prevention of biofilm development due to surface treatment and/or plasma steered application of antimicrobial active layers with drug delivery function on foreign objects implanted into humans (implantable prosthesis, contact lenses, stents etc.) as well as elimination of biofilms by direct action of ttp on surfaces and tissues (chronic wounds, tooth surface, prosthesis) promotion of the incorporation of implants into viable tissue by changing the surface of materials (hydrophobicity) Promotion of penetration of topically applied drugs with therapeutic results Assessment of veterinary indications Improved cleaning performance in reprocessing of medical devices by surface modification.  相似文献   
95.
96.
The catalytic dehydrogenation (DH) and oxidative dehydrogenation (ODH) of light alkanes are of significant industrial importance. In this work both carbonaceous material deposited on VOx/Al2O3 catalysts during reaction and unsupported carbon nanofibres (CNFs) are shown to be active for the dehydrogenation of butane in the absence of gas-phase oxygen. Their activity in these reactions is shown to be dependent upon their structure, with different reaction temperatures yielding structurally different coke deposits. Terahertz time-domain spectroscopy (THz-TDS), among other techniques, has been applied to the characterisation of these deposits – the first time this technique has been employed in coke studies. TEM and other techniques show that coke encapsulates the catalyst, preventing access to VOx sites, without a loss of activity. Studies on CNFs confirm that carbonaceous materials act as catalysts in this reaction. Carbon-based catalysts represent an important new class of potential catalysts for DH and ODH reactions.  相似文献   
97.
Copper-catalyzed alkyne-azide “click chemistry” is applied in the preparation of tadpole-shaped (“monochelic”) POSS-end functional hybrid polymers by combining with ATRP and RAFT polymerization. Alkyne-functionalized ATRP initiator and RAFT agent were respectively synthesized and applied in the preparation of alkyne-terminal poly(methyl methacrylate) and polystyrene. The tadpole-shaped POSS-containing hybrid polymers are easily obtained by the click reaction with an azido-functional POSS molecule. This presents a novel and effective method to prepare POSS-containing hybrid polymers.  相似文献   
98.
Canavalia brasiliensis (canavalia), a drought tolerant legume, was introduced into the smallholder traditional crop-livestock production system of the Nicaraguan hillsides as green manure to improve soil fertility or as forage during the dry season for improving milk production. Since nitrogen (N) is considered the most limiting nutrient for agricultural production in the target area, the objective of this study was to quantify the soil surface N budgets at plot level in farmers fields over two cropping years for the traditional maize/bean rotation and the alternative maize/canavalia rotation. Mineral fertilizer N, seed N and symbiotically fixed N were summed up as N input to the system. Symbiotic N2 fixation was assessed using the 15N natural abundance method. Nitrogen output was quantified as N export via harvested products. Canavalia derived in average 69% of its N from the atmosphere. The amount of N fixed per hectare varied highly according to the biomass production, which ranged from 0 to 5,700 kg ha?1. When used as green manure, canavalia increased the N balance of the maize/canavalia rotation but had no effect on the N uptake of the following maize crop. When used as forage, it bears the risk of a soil N depletion up to 41 kg N ha?1 unless N would be recycled to the plot by animal manure. Without N mineral fertilizer application, the N budget remains negative even if canavalia was used as green manure. Therefore, the replenishment of soil N stocks by using canavalia may need a few years, during which the application of mineral N fertilizer needs to be maintained to sustain agricultural production.  相似文献   
99.
Biohydrometallurgy as a section of hydrometallurgy uses specific metabolic capabilities of microorganisms for metal extraction. Biomining is the application of bioleaching for metal extraction from sulfide ores. For recycling, i.e., metal extraction from waste and industrial residues, there are no biohydrometallurgical technologies yet, but promising laboratory studies on metal extraction from solids. In this review article, these are summarized, and perspectives are shown.  相似文献   
100.
介绍了Voith造纸技术控股股份有限公司近期研发的新技术和新装备,包括CompactPulper 损纸碎浆机,经过优化设计的回收浆车间废渣处理系统,适合于所有纸种脱水的靴式压榨技术--NipcoFlex和TissueFlex,PrintFlex P压榨毛布,VTT真空引纸系统,Duoshake摇振器,Strato系列橡胶包覆层新品种等.  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