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   8330篇
  免费   579篇
  国内免费   302篇
电工技术   606篇
综合类   438篇
化学工业   867篇
金属工艺   392篇
机械仪表   374篇
建筑科学   399篇
矿业工程   169篇
能源动力   171篇
轻工业   790篇
水利工程   173篇
石油天然气   174篇
武器工业   32篇
无线电   640篇
一般工业技术   674篇
冶金工业   2268篇
原子能技术   104篇
自动化技术   940篇
  2024年   30篇
  2023年   88篇
  2022年   238篇
  2021年   275篇
  2020年   200篇
  2019年   152篇
  2018年   173篇
  2017年   179篇
  2016年   168篇
  2015年   237篇
  2014年   324篇
  2013年   380篇
  2012年   463篇
  2011年   468篇
  2010年   431篇
  2009年   429篇
  2008年   497篇
  2007年   422篇
  2006年   355篇
  2005年   290篇
  2004年   254篇
  2003年   190篇
  2002年   175篇
  2001年   165篇
  2000年   122篇
  1999年   106篇
  1998年   616篇
  1997年   420篇
  1996年   260篇
  1995年   153篇
  1994年   124篇
  1993年   147篇
  1992年   43篇
  1991年   28篇
  1990年   32篇
  1989年   36篇
  1988年   37篇
  1987年   29篇
  1986年   25篇
  1985年   29篇
  1984年   21篇
  1983年   12篇
  1982年   20篇
  1981年   24篇
  1980年   27篇
  1979年   9篇
  1978年   11篇
  1977年   76篇
  1976年   151篇
  1975年   10篇
排序方式: 共有9211条查询结果,搜索用时 125 毫秒
1.
2.
本文介绍了柳钢冷轧板带厂1550 mm单机架平整机机前甩尾轧制的工艺。改进前轧制每卷钢卷生产效率低,钢卷成材率低,改进后生产效率、成材率明显提高,部分规格的钢卷能实现带尾剪切长度为零。  相似文献   
3.
For the training of academic skills, digital educational games with integrated adaptivity are promising. Adaptive games are considered superior to non-adaptive games, because they constantly assess children's performance, and accordingly adapt the difficulty of the tasks corresponding to the children's individual level. However, empirical evidence with regard to the effectivity of adaptive compared to non-adaptive games is limited. A study was conducted with 191 children from the third year of Kinder garten who were enrolled in one of three conditions, that is, playing an adaptive version of the reading game (RG), a non-adaptive version of the RG or training with pen-and-paper exercises. In all three conditions, children trained emergent reading (phonological awareness and letter knowledge) once a week for 30 min over a period of 5 weeks. Children's performance on cognitive (phonological awareness, letter knowledge, reading fluency) and non-cognitive (motivation, self-concept) factors was assessed. Results revealed a significant improvement in phonological awareness and letter knowledge in all conditions. However, no differences between the conditions were observed with respect to children's improvement on phonological awareness and letter knowledge or on their post-test scores for reading fluency. With regard to motivation and self-concept, again, no differences in these non-cognitive factors were observed across conditions.  相似文献   
4.
The correct separation of chromosomes during mitosis is necessary to prevent genetic instability and aneuploidy, which are responsible for cancer and other diseases, and it depends on proper centrosome duplication. In a recent study, we found that Smy2 can suppress the essential role of Mps2 in the insertion of yeast centrosome into the nuclear membrane by interacting with Eap1, Scp160, and Asc1 and designated this network as SESA (S my2, E ap1, S cp160, A sc1). Detailed analysis showed that the SESA network is part of a mechanism which regulates translation of POM34 mRNA. Thus, SESA is a system that suppresses spindle pole body duplication defects by repressing the translation of POM34 mRNA. In this study, we performed a genome-wide screening in order to identify new members of the SESA network and confirmed Dhh1 as a putative member. Dhh1 is a cytoplasmic DEAD-box helicase known to regulate translation. Therefore, we hypothesized that Dhh1 is responsible for the highly selective inhibition of POM34 mRNA by SESA.  相似文献   
5.
在编制遥测数据处理软件的过程中,面对大量的测试数据,经常需要编写高效率的数据过滤器。本文讨论了一种通过采用跨单元、跨类访问Delphi类的私有域的方法实现快速删除TList批连续结点的新算法,并通过测试结果得到验证。  相似文献   
6.
分别利用Ga2O3粉末和Ga2O3凝胶作为Ga源,采用NH3为N源,在950℃下,分别将两种反应物与流动的NH3反应20 min合成了GaN微晶。用X射线衍射(XRD)、扫描电子显微镜(SEM)、选择区电子衍射(SAED)对微晶进行结构、形貌的分析,特别是对两种不同途径合成GaN微晶的XRD进行了分析比较。结果表明,当Ga源温度为950℃时两种不同的合成途径均可得到六方纤锌矿结构的GaN单晶颗粒,在氮化温度为850℃和900℃时,利用Ga2O3粉末作为Ga源,仅有少量的Ga2O3转变为GaN;而采用Ga2O3凝胶作为Ga源,在相同的温度下,大部分凝胶经过高温氨化反应均可转化为GaN。  相似文献   
7.
许参  艾晓辉  王超 《电子器件》2003,26(2):122-124
设计了GMSK(Gauss Minimum Shift Keying,高斯最小频移键控)无线接收终端的硬件与软件系统。硬件的射频电路对空中信号进行接收与滤波,再由以MX589构成的解调模块解调,输出数字信号;数字硬件以单片机GMS97L5为核心。软件系统设计了对IC卡AT88SCl608加密卡的认证以及对串行数据的接收与处理的中断程序。终端系统接收数据快、性能稳定。  相似文献   
8.
研究了Windows操作系统中网络电话软件的实时播放音频的策略。在非实时系统中,音频播放程序不能严格地被定时执行,播放缓冲区被耗尽而产生播放空隙。采用DirectSound技术,以ms为单位来控制音频的播放,并根据负载的变化动态地调整每一个话音期的门限值来减少播放空隙。实验结果表明,该算法能够以较小的时延为代价来获取平滑的播放效果。  相似文献   
9.
Motor vehicle accidents are the main cause of death and disability between 1 and 4 years of age. Since 1980 the Academy of Pediatrics has been promoting the correct use of car seats. The major reason that car seats are not fulfilling their full potential is their incorrect or lack of use. In order to evaluate parental knowledge about car seat use for children and their actual use in the population visiting HURRA, a survey was performed which demonstrated that only 57.6% of the parents interviewed had infant car seats and that only 83.3% of owners actually use it. As many as 94.4% had correct knowledge about car seat use, but the majority of correct information was not provided by the medical staff. The majority of parents use seat belts for their own protection but a significantly smaller percentage use car seats for their own children.  相似文献   
10.
A preliminary report presenting the results of fibular strut grafting in the severely resorbed mandibular and maxillary region is presented. Thirteen patients were treated due to severe resorption of alveolar and basilar bone of 49 segments of the mandible and the maxilla. Two patients additionally had pathological fractures of the mandible. In 10 cases the strut graft was harvested by means of a new minimally invasive technique. After modelling the fibular bone it was fixed to the recipient site by miniscrews or implants. After a mean follow-up period of 20 months (max. 31, min. 11 months) a retrospective analysis of clinical and radiological findings was carried out. It showed that a mean augmentation of 16 mm was achieved. Compared to other studies the fibular strut graft was resorbed less, and due to the primary stability it could be used for the treatment of fractures of the mandible. No more than natural resorption was observed when the patients received their prostheses fixed to dental implants.  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