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   58009篇
  免费   5333篇
  国内免费   2801篇
电工技术   3627篇
技术理论   8篇
综合类   3780篇
化学工业   9882篇
金属工艺   3074篇
机械仪表   3473篇
建筑科学   4128篇
矿业工程   1583篇
能源动力   1819篇
轻工业   3779篇
水利工程   1144篇
石油天然气   3011篇
武器工业   657篇
无线电   7118篇
一般工业技术   7054篇
冶金工业   3024篇
原子能技术   732篇
自动化技术   8250篇
  2024年   272篇
  2023年   957篇
  2022年   1900篇
  2021年   2599篇
  2020年   1924篇
  2019年   1572篇
  2018年   1764篇
  2017年   1893篇
  2016年   1708篇
  2015年   2381篇
  2014年   2829篇
  2013年   3613篇
  2012年   3733篇
  2011年   3963篇
  2010年   3487篇
  2009年   3383篇
  2008年   3257篇
  2007年   3075篇
  2006年   3126篇
  2005年   2585篇
  2004年   1946篇
  2003年   1687篇
  2002年   1747篇
  2001年   1589篇
  2000年   1368篇
  1999年   1388篇
  1998年   1189篇
  1997年   1032篇
  1996年   831篇
  1995年   693篇
  1994年   519篇
  1993年   437篇
  1992年   340篇
  1991年   271篇
  1990年   185篇
  1989年   181篇
  1988年   147篇
  1987年   86篇
  1986年   88篇
  1985年   77篇
  1984年   34篇
  1983年   27篇
  1982年   37篇
  1981年   34篇
  1980年   24篇
  1979年   21篇
  1977年   16篇
  1976年   19篇
  1974年   13篇
  1973年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
根据膳食营养的要求,以燕麦、爆裂玉米、奶粉、鸡胸肉、胡萝卜和香菜为原料,采用微波技术和冷冻干燥技术生产均衡营养早餐,确定了最佳的配方为燕麦片15g、爆裂玉米8g、奶粉10g、鸡肉丁5g、胡萝卜丁0.5g、香菜干0.5g、盐或糖1g.  相似文献   
112.
丙烯酸高碳醇酯的合成   总被引:1,自引:0,他引:1  
介绍了降凝剂中间体丙烯酸高碳醇酯的合成和产品分离提纯方法。考察了合成条件对酯化反应的影响,结果表明,在原料丙烯酸与十八醇摩尔比1.2:1,阻聚剂对苯二酚用量占原料总量1.5%,催化剂对甲苯磺酸用量占原料总量1.5%,反应温度80-86℃,回流反应时间6h条件下,酯化率最高达89%。产品分离提纯方法与传统分离方法比较,所需分离时间短,洗涤用水量少,而产品收率远高于传统分离方法,达95%以上。  相似文献   
113.
A semiconductor factory contains hundreds of pieces of equipment. More reliable service by equipment managers is required to increase the utilization of equipment and improve product quality and yield. Therefore, developing a reliable service management scheme (SMS) for semiconductor factory management systems is essential. This study presents an SMS that applies Jini Technology and uses the design by contract technologies. The SMS has error-detecting and function-replacing capabilities. The SMS detects the malfunctioning of an equipment manager (service) and sends an event notice to the factory manager. The GEV in the SMS archives the credit values of all of the equipment managers so that the factory manager can select better equipment managers for service by checking their credit values. The illustrative example and the evaluation of the reliability improvement reveal that the proposed SMS provides an efficient, reliable, fault tolerant, and cost-effective mechanism for semiconductor factory management systems. Lastly, this illustrative example is successfully implemented and demonstrated and the core technology of SMS is transferred to and commercialized by Charming Systems Corporation.  相似文献   
114.
115.
3.5代移动通信中的链路自适应技术使用自适应调制编码和快速混合重传技术替代了3代中使用的功率控制技术。仿真结果比较了这两种新技术与功率控制技术的性能,证明了这两个新技术显著地提高了网络平均的吞吐量。  相似文献   
116.
117.
本文介绍了反应注射成型新工艺和演变过程,论述反应注射成型工艺所需新材料及其发展.  相似文献   
118.
119.
The binding of 125I-labelled tissue plasminogen activator (tPA), the tPA A- or B-chain to endothelial cells (EC) were studied in suspensions of cultured human umbilical vein EC (HUVEC) or immortalized microvascular EC (HMEC). By determinations of the concentration-dependent binding it was shown that both the A-chain and the B-chain, which were isolated after partial reduction of two-chain tPA, contain ligands for binding to EC. The affinity for the B-chain was much higher than for the A-chain according to Scatchard analysis (Kd 24 and 515 nM, respectively), whereas the number of binding sites was higher for the A-chain than for the B-chain (Bmax 8 x 10(5) and 1.2 x 10(5), respectively). There were no cross interactions between the A- and B-chains and their binding sites. The binding of tPA to EC induced an almost 100-fold increase of the activation rate when compared to the same amount of enzyme in free solution, which in contrast to the fibrin-induced stimulation was not inhibited by antibodies against fibrin. The enzymatic activity of the B-chain was much less affected by the association to the cells. Both tPA and the tPA B-chain were largely protected against inhibition by an excess plasminogen activator type-1 (PAI-1) when bound to EC, whereas the same amount of free tPA was totally inactivated. The competition studies strongly indicated that an N-terminal segment in the B-chain, AKHRRSPGER, may be the ligand part of the B-chain. It is interesting to note that this polypeptide segment also participates in a binding site for PAI-1, necessary for effective inhibition. This implies a possible competition between PAI-1 and a tPA-receptor for binding of tPA. High molecular weight urokinase had no quenching effect on the binding of the B-chain to EC.  相似文献   
120.
Designing circuits with partial scan   总被引:1,自引:0,他引:1  
In this scan design methodology, only selected faults are targeted for detection. These faults are those not detected by the designer's functional vectors. The test generator decides exactly which flip-flops should be scanned using one of two methods. In the first method, all possible tests are generated for each target fault, and the set of tests requiring the fewest flip-flops is selected. In the second method, only one test is generated for each fault, and the use of flip-flops is avoided as much as possible during test generation. Examples of actual VLSI circuits show a savings of at least a 40% in full-scan overhead  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