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   11279篇
  免费   337篇
  国内免费   41篇
电工技术   121篇
综合类   23篇
化学工业   2082篇
金属工艺   170篇
机械仪表   230篇
建筑科学   572篇
矿业工程   31篇
能源动力   172篇
轻工业   773篇
水利工程   53篇
石油天然气   11篇
武器工业   1篇
无线电   590篇
一般工业技术   1443篇
冶金工业   3837篇
原子能技术   70篇
自动化技术   1478篇
  2023年   51篇
  2022年   100篇
  2021年   142篇
  2020年   104篇
  2019年   121篇
  2018年   168篇
  2017年   110篇
  2016年   191篇
  2015年   192篇
  2014年   249篇
  2013年   562篇
  2012年   397篇
  2011年   545篇
  2010年   412篇
  2009年   389篇
  2008年   432篇
  2007年   421篇
  2006年   363篇
  2005年   312篇
  2004年   295篇
  2003年   225篇
  2002年   228篇
  2001年   176篇
  2000年   165篇
  1999年   239篇
  1998年   986篇
  1997年   639篇
  1996年   429篇
  1995年   295篇
  1994年   235篇
  1993年   292篇
  1992年   151篇
  1991年   92篇
  1990年   117篇
  1989年   97篇
  1988年   109篇
  1987年   84篇
  1986年   74篇
  1985年   91篇
  1984年   94篇
  1983年   63篇
  1982年   78篇
  1981年   94篇
  1980年   89篇
  1979年   86篇
  1978年   73篇
  1977年   120篇
  1976年   171篇
  1975年   59篇
  1973年   47篇
排序方式: 共有10000条查询结果,搜索用时 70 毫秒
81.
We have measured the heat capacities of3He films and liquid3He in porous Vycor glass at 10 to 600 mK. With increasing the film thickness from 1 to 3 atomic layers, the specific heat evolves gradually from that typical to solid to that of liquid3He. At about 2 atomic layers, however, its low-temperature part is nearly temperature-independent; we interpret this as a result of gradual freezing of spins in an amorphous solid3He film with decreasing the temperature. The contribution of liquid3He in the center of the Vycor pores can be described as the specific heat of bulk liquid3He at corresponding pressures in the range 0 to 28 bar. The thickness of amorphous solid on the pore walls increases with external pressure roughly linearly. Preplating the walls with4He allows to determine the positions of3He atoms contributing to the surface specific heat at 10 to 50 mK. In addition, the contribution from the specific heat of3 He -4He mixing at 100 to 600 mK is discussed as a function of pressure and amount of4He.0n leave from ISSP Acad. Sci. of Russia, Chernogolovka, Russia  相似文献   
82.
83.
Ultrafiltration and thermization of milk on dairy farms in France have been under study since 1979. More recently five dairy farms in Brittany have been routinely producing 2:1 whole milk retentate for Emmental and St. Paulin cheese making. The milk processed is ultrafiltered at 35°C and thermized at 72°C for 15 s in an Ultratherm unit. Cheese quality generally appears satisfactory.In Eastern France a new specialty cheese industry has been started utilizing 4.5:1 whole milk retentate produced by ultrafiltration conducted at 40°C. The specialty cheese attains its characteristic white surface from Penicillium album mold. It has a bland, nutty flavor and very soft, smooth texture. A surface bluing phenomenon occurs after 14 d.  相似文献   
84.
着重介绍Raychem电路保护部的PolySwitch PPTC(聚合物正温度系数)元件在电源管理中提供电流过载和温度过载的保护过程。另外还介绍了电源适配器、CLA(点烟器)、移动电话设备及电池板的保护装置是如何进一步改善实际使用中的总体可靠性的。  相似文献   
85.
86.
87.
Nickel molybdate catalysts used in several different upgrading reactions of coal-derived materials from low-rank Australian coals have been regenerated and their activity assessed using a number of physical and chemical techniques. Regeneration of spent coked catalysts for 20 hours in air at 450°C was sufficient to restore chemical hydrogenation activity to catalyst used for pre-asphaltene, asphaltene and oil upgrading, provided poisoning of the catalyst surface by other impurities, principally chlorine-containing molecules, had not occurred.  相似文献   
88.
In human leukemias and lymphomas nonrandom chromosomal rearrangements cause changes in cell growth and/or survival in such a way as to promote malignancy. The detailed study of the biochemical and genetic pathways altered in human cancer requires the identification or development of models to allow the study and manipulation of cancer gene function. Recently, the breakpoint gene TCL1, involved in chromosome translocations observed mostly in mature T-cell proliferations and chronic lymphocytic leukemias (CLL), was isolated and characterized, and showed to be part of a new gene family of proteins involved in these tumors. The murine Tcl1 gene, is similar in sequence to the murine and human MTCP1 gene also involved in T cell leukemias. The murine Tcl1 gene was shown to reside on mouse chromosome 12 in a region syntenic to human chromosome 14. Furthermore, we show that the murine Tcl1 gene is expressed early in mouse embryonic development and demonstrates expression in fetal hematopoietic organs as well as in immature T and B cells. Characterization of the murine Tcl1 gene will help in developing a mouse model of CLL and would provide the best opportunity to study and decipher the role of TCL1 in malignant transformation.  相似文献   
89.
90.
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