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   4064篇
  免费   19篇
  国内免费   6篇
电工技术   14篇
综合类   2篇
化学工业   109篇
金属工艺   17篇
机械仪表   11篇
建筑科学   18篇
矿业工程   1篇
能源动力   21篇
轻工业   38篇
水利工程   2篇
石油天然气   3篇
无线电   45篇
一般工业技术   137篇
冶金工业   3616篇
原子能技术   2篇
自动化技术   53篇
  2021年   9篇
  2019年   5篇
  2018年   8篇
  2017年   7篇
  2016年   7篇
  2015年   10篇
  2014年   12篇
  2013年   24篇
  2012年   29篇
  2011年   39篇
  2010年   28篇
  2009年   20篇
  2008年   22篇
  2007年   27篇
  2006年   20篇
  2005年   18篇
  2004年   16篇
  2003年   27篇
  2002年   16篇
  2001年   9篇
  2000年   13篇
  1999年   110篇
  1998年   1120篇
  1997年   593篇
  1996年   447篇
  1995年   236篇
  1994年   217篇
  1993年   224篇
  1992年   33篇
  1991年   39篇
  1990年   55篇
  1989年   53篇
  1988年   58篇
  1987年   57篇
  1986年   52篇
  1985年   28篇
  1984年   4篇
  1983年   12篇
  1982年   17篇
  1981年   20篇
  1980年   34篇
  1979年   6篇
  1978年   8篇
  1977年   85篇
  1976年   180篇
  1975年   7篇
  1972年   4篇
  1967年   6篇
  1962年   3篇
  1955年   3篇
排序方式: 共有4089条查询结果,搜索用时 15 毫秒
121.
Fungal strains were screened for lipase producing activities and 10 strains were classified as good producers. Aspergillus sp., Fusarium sp., and Penicillium sp. exhibited the highest activities when fermented in wheat bran (WB) and soybean bran (SB). No fungal growth was observed using sugarcane bagasse (CB). An experimental design was applied to incorporate CB into the fermentation process for lipase production by Aspergillus sp. and Penicillium sp., and to evaluate the best moisture content for the substrate. Strains studied achieved maximum lipase activities with 25% CB combined with 75% WB or SB at 40% moisture content. The highest lipase activities were observed for WB and SB, and for SB combined with CB using Aspergillus sp. Fermentation of 96 h was the optimum period for enzyme production.  相似文献   
122.
123.
124.
The photo-vulcanization with versatile thiol-ene chemistry represents an innovative approach to crosslink diene-rubber materials both in latex and in solid film state. In this work, the structure of elastomer-based thiol-ene networks and the morphology after film formation are studied in detail using electron microscopic techniques, atomic force microscopy and multiple-quantum solid-state NMR spectroscopy. Additionally, film formation properties and corresponding macroscopic properties of photo-vulcanized natural rubber (NR) latex and its synthetic counterpart, isoprene rubber (IR) latex, are determined in dependence on the curing procedure (pre- and post-vulcanization). The results reveal that thiol-ene cured elastomers comprise homogenously distributed crosslinks with a low amount of short chain defects. Whilst photochemically pre-cured NR latex particles provide coherent films, the film formation and mechanical properties of IR are strongly governed by the crosslink density of the latex particles. In film state, photo-vulcanization promotes narrow crosslink distributions and excellent tensile properties of both NR and IR.  相似文献   
125.
局部腐蚀,包括点腐蚀、应力腐蚀开裂和腐蚀疲劳是导致电厂发电装置损伤的重要原因,它们诱发50%以上的意外停机事故。迄今,腐蚀破坏的预测一直沿用经验和统计的方法,但是,由于已证实该方法的适用性和其结果的准确性欠佳,故不宜作为例行检修规程的基础。本文提出了预测局部腐蚀损伤的决定论方法,并使用这个方法说明点腐蚀如何引发低压蒸汽轮机涡轮盘Wilson线下游部位的应力腐蚀开裂(SCC),我们的计算表明SCC的萌发与扩展对蒸汽小氧含量、冷凝液膜的环境和涡轮盘所承受的应力这三个因素敏感。  相似文献   
126.
On-line service reservation is becoming increasingly popular in the service industry. As services become more complex, requiring co-ordination among individual actions, the planning for making service appointments is normally conducted manually by the operators, often resulting in slow responses to customers. To tackle this problem, we have developed a real-time service reservation portal that takes an order from a user and works out appointment options, based on the availability of enterprise resources, for the user to book on-line. The portal is capable of dealing with complex workflow appointing, supporting interactive fine-tuning in individual appointments, respecting customer preferences and work policies, monitoring progress of workflow, informing the customer of status changes in job scheduling, dispatching and execution, as well as handling exceptions automatically. We have integrated the portal, code-named FieldReserve, with other components in the BT fieldforce optimisation suite (FOS) that covers functions of resource planning, scheduling and execution for the fieldforce to demonstrate the feasibility and potential benefits of this technology. Benefits demonstrated are to provide customers with instant response of service reservation, to provide volume control on reservation, to break away from one-size-fits-all lead times for service fulfilment, to provide customers with equal access to service provision, and to bring transparency of service progress to customers. Currently, we are actively engaging with businesses and have obtained strong support to downstream the key values of this technology in commercial contexts.  相似文献   
127.
Fluorine plasma treatment is applied to cross-link a novolak based negative tone optical resist (maN-2400) to achieve increased dry etching selectivity. Furthermore, fluorine plasma treatment is used to strengthen the same resist to keep it in place during a second lithography step on top of the first one. Using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, cross-linking and passivation of the resist during plasma treatment is demonstrated. In contrast to the application of a baking process after resist development, AFM images show that fluorine plasma treatment preserves the intrinsic structure of the resist.  相似文献   
128.
129.
130.
Color filters are produced using semiconductor production techniques although problems with low yield remain to be addressed. This study presents a new means of selective removal using excimer irradiation, chemical etching, or electrochemical machining on the fifth generation TFT LCDs. The selective removal of microstructure layers from the color filter surface of an optoelectronic flat panel display, as well as complete removal of the ITO thin-films, RGB layer, or resin black matrix (BM) layer from the sub...  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