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   10667篇
  免费   694篇
  国内免费   306篇
电工技术   362篇
综合类   382篇
化学工业   1588篇
金属工艺   522篇
机械仪表   614篇
建筑科学   501篇
矿业工程   171篇
能源动力   313篇
轻工业   462篇
水利工程   150篇
石油天然气   298篇
武器工业   30篇
无线电   1434篇
一般工业技术   1567篇
冶金工业   1904篇
原子能技术   92篇
自动化技术   1277篇
  2024年   42篇
  2023年   131篇
  2022年   250篇
  2021年   332篇
  2020年   266篇
  2019年   271篇
  2018年   264篇
  2017年   261篇
  2016年   256篇
  2015年   345篇
  2014年   407篇
  2013年   592篇
  2012年   547篇
  2011年   594篇
  2010年   491篇
  2009年   515篇
  2008年   459篇
  2007年   457篇
  2006年   416篇
  2005年   398篇
  2004年   271篇
  2003年   272篇
  2002年   258篇
  2001年   249篇
  2000年   212篇
  1999年   290篇
  1998年   530篇
  1997年   385篇
  1996年   302篇
  1995年   226篇
  1994年   192篇
  1993年   168篇
  1992年   101篇
  1991年   96篇
  1990年   76篇
  1989年   84篇
  1988年   85篇
  1987年   67篇
  1986年   56篇
  1985年   58篇
  1984年   33篇
  1983年   23篇
  1982年   40篇
  1981年   37篇
  1980年   27篇
  1979年   15篇
  1978年   16篇
  1977年   48篇
  1976年   81篇
  1974年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Fenbendazole (Hoechst India Ltd.) was incorporated at 0.5 g/kg into urea molasses blocks made by two different processes. The proportion of the drug remaining in the blocks and the plasma concentrations of the parent compound and its metabolites were measured. Recovery of the drug in blocks made by the cold and the modified hot processes was 90% and 96%, respectively. The plasma metabolite profile revealed a plateau between days 4 and 6 of feeding in cattle and buffalo. However, the plasma concentrations of fenbendazole and its metabolites were low in buffalo compared to cattle.  相似文献   
32.
文中严格地讨论了任意截面形状,任意模式的柱形谐振腔Q值与构成该谐振器的传输线衰减常数间的关系,给出了更一般的公式,推广了Davidson和Sim-monds^[1]、Barlow和Cullen^[2]以及Yeh和Shimabukuro^[3,4]的结果。  相似文献   
33.
The bicycle industry is an interesting case where East Asian firms have made a considerable impact, but where Taiwan has outperformed Korea. In the Korean sector, none of the well-known chaebol such as Samsung have become involved, and the incumbent firms experienced slow growth until there was government intervention in the 1980s. In Taiwan, small dynamic firms responded to large export orders in the early 1970s, and established a lasting lead which has been regenerated through technological upgrading. The paper argues that both countries’ bicycle industries have a vertically non-integrated structure, with extensive internal sub-contracting, and that the differences between the countries can be attributed to the timing and effcacy of industrial policy interventions.  相似文献   
34.
PURPOSE: To demonstrate a superselective intraarterial chemotherapy as a therapeutic alternative in the treatment of previously treated recurrent lymph node metastases in breast cancer. METHODS: 14 patients with recurrent lymph node metastases in cases of breast cancer were presented to be treated by intraarterial chemotherapy of 25 mg mitoxantrone/m2 over a period of 24 hours. In two patients with superclavicular lymph node involvement an intraarterial therapy could not be carried out because of a vascular connection to the anterior spinal artery. Involved lymph stations could be reached in superselective technique by side branches of the subclavian artery. Heparin coverage was given intravenously. Every patient had had surgery, radiation, systemic chemo- and hormonal therapy before and was now graded as inoperable. Therapy indication was given by local tumour-induced symptoms. RESULTS: In the 12 treated cases complete remission was seen in three, partial remission in 4, a steady state in two and a progressive disease in three. There were no complications or severe side effects. CONCLUSION: Intraarterial chemotherapy is an effective and well tolerated treatment in recurrent lymph node metastases in cases of breast cancer even if conventional therapies can no longer be used.  相似文献   
35.
本文讨论了用辉光放电法制备氮化硅薄膜时衬底温度、射频功率和气体流量比对薄膜的电导率、介电常数和击穿强度的影响。通过优化生长条件,制备了优质非晶氮化硅薄膜,其介电常数为7.5、击穿强度为5.5MV/cm、电导率为10-13(Ωcm)-1。  相似文献   
36.
37.
对传统双曲线极尖的四极透镜进行了磁性能分析。在此基础上,提出了极尖断面为折线的四极透镜结构。磁场的数值分析以及测量结果表明:该结构产生的场梯度均匀,且具有磁场集中、磁场梯度高、便于加工和安装的对称性控制等优点。该结构的四极透镜已用于CYCIAE-30回旋加速器和HI-13串列加速器束流输运线之中  相似文献   
38.
Bi-layer CoCrTa/Cr films were deposited on textured aluminium or textured NiP-plated aluminium substrate by d.c. magnetron sputtering. The crystal anisotropy and thereby magnetic properties depending on substrate material, substrate temperature and texturing, were investigated. The magnetic crystal anisotropy induced by the mechanical texture on aluminium or NiP/Al substrates along the texture lines for the film deposited at high temperature, were clearly observed, while the film deposited at low temperature shows less prominent anisotropic behaviour. X-ray diffraction analysis indicates a change in the preferred orientation of the chromium and CoCrTa films sputtered on different substrates at different temperatures. It was found that a high substrate temperature was beneficial to the formation of Cr(002) and therefore epitaxial growth of Co(11¯20) on Cr(002) for either aluminium or NiP/Al substrates.  相似文献   
39.
40.
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