全文获取类型
收费全文 | 265163篇 |
免费 | 3459篇 |
国内免费 | 1109篇 |
专业分类
电工技术 | 4870篇 |
技术理论 | 1篇 |
综合类 | 974篇 |
化学工业 | 42901篇 |
金属工艺 | 16149篇 |
机械仪表 | 10930篇 |
建筑科学 | 5243篇 |
矿业工程 | 4054篇 |
能源动力 | 4358篇 |
轻工业 | 11358篇 |
水利工程 | 4421篇 |
石油天然气 | 13561篇 |
武器工业 | 134篇 |
无线电 | 21878篇 |
一般工业技术 | 64909篇 |
冶金工业 | 33895篇 |
原子能技术 | 11296篇 |
自动化技术 | 18799篇 |
出版年
2021年 | 3711篇 |
2020年 | 2816篇 |
2019年 | 3220篇 |
2018年 | 5963篇 |
2017年 | 6345篇 |
2016年 | 6590篇 |
2015年 | 3765篇 |
2014年 | 6240篇 |
2013年 | 11110篇 |
2012年 | 8440篇 |
2011年 | 10145篇 |
2010年 | 8301篇 |
2009年 | 9064篇 |
2008年 | 9068篇 |
2007年 | 8655篇 |
2006年 | 7093篇 |
2005年 | 6146篇 |
2004年 | 5894篇 |
2003年 | 5643篇 |
2002年 | 5459篇 |
2001年 | 5255篇 |
2000年 | 5182篇 |
1999年 | 4493篇 |
1998年 | 7623篇 |
1997年 | 6171篇 |
1996年 | 4662篇 |
1995年 | 3806篇 |
1994年 | 3557篇 |
1993年 | 3746篇 |
1992年 | 3266篇 |
1991年 | 3397篇 |
1990年 | 3533篇 |
1989年 | 3404篇 |
1988年 | 3300篇 |
1987年 | 3289篇 |
1986年 | 3179篇 |
1985年 | 3342篇 |
1984年 | 3276篇 |
1983年 | 3163篇 |
1982年 | 3011篇 |
1981年 | 3083篇 |
1980年 | 3094篇 |
1979年 | 3272篇 |
1978年 | 3502篇 |
1977年 | 3486篇 |
1976年 | 3944篇 |
1975年 | 3219篇 |
1974年 | 3293篇 |
1973年 | 3344篇 |
1972年 | 2992篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Measurement Techniques - A method is proposed for transferring the unit of mean power of laser radiation by means of measuring high-intensity power (kilowatts), with the possibility of constant... 相似文献
72.
Semiconductors - On the basis of the Monte Carlo algorithm, a method for calculating the energy spectrum of hot nonequilibrium electrons and holes in the track of a primary recoil atom after being... 相似文献
73.
74.
75.
Programming and Computer Software - Image segmentation using a hierarchical sequence of piecewise constant approximations that minimally differ from the original image in terms of the total squared... 相似文献
76.
77.
78.
Roberto Zefferino Claudia Piccoli Sante Di Gioia Nazzareno Capitanio Massimo Conese 《International journal of molecular sciences》2021,22(5)
Connexin- and pannexin (Panx)-formed hemichannels (HCs) and gap junctions (GJs) operate an interaction with the extracellular matrix and GJ intercellular communication (GJIC), and on account of this they are involved in cancer onset and progression towards invasiveness and metastatization. When we deal with cancer, it is not correct to omit the immune system, as well as neglecting its role in resisting or succumbing to formation and progression of incipient neoplasia until the formation of micrometastasis, nevertheless what really occurs in the tumor microenvironment (TME), which are the main players and which are the tumor or body allies, is still unclear. The goal of this article is to discuss how the pivotal players act, which can enhance or contrast cancer progression during two important process: “Activating Invasion and Metastasis” and the “Avoiding Immune Destruction”, with a particular emphasis on the interplay among GJIC, Panx-HCs, and the purinergic system in the TME without disregarding the inflammasome and cytokines thereof derived. In particular, the complex and contrasting roles of Panx1/P2X7R signalosome in tumor facilitation and/or inhibition is discussed in regard to the early/late phases of the carcinogenesis. Finally, considering this complex interplay in the TME between cancer cells, stromal cells, immune cells, and focusing on their means of communication, we should be capable of revealing harmful messages that help the cancer growth and transform them in body allies, thus designing novel therapeutic strategies to fight cancer in a personalized manner. 相似文献
79.
N. P. Shapkin A. A. Kapustina N. V. Dombai V. V. Libanov I. G. Khalchenko S. V. Gardionov V. V. Gribova 《Polymer Bulletin》2020,77(3):1177-1190
Interaction of molybdenyl(VI) bis(acetylacetonate) with polyphenylsiloxane in xylene and under mechanochemical activation conditions has been investigated. The interaction in solution proceeds with splitting of the siloxane bond and formation of polymolybdenum(VI) phenylsiloxane with different silicon/metal ratios. The fractions with the silicon/metal ratio < 2 are characterized with high degree of crystallinity and low solubility, whereas those with the ratio > 2 are amorphous. The interaction of the above reagents under mechanical activation conditions proceeds with the formation of soluble polymers similar to those obtained in a solution with the silicon/molybdenum ratio equal to 2.6. The crystal chemistry parameters of the fraction obtained in solution with the ratio Si/Mo equals to 1:2 have been calculated on the basis of the X-ray diffraction analysis data using the Debye–Shearer equation. It has been demonstrated that the chain cross section found using the Miller–Boyer method coincides with that calculated geometrically on the basis of literature data on bond lengths and angles. It is shown that the interaction of molybdenyl(VI) bis(acetylacetonate) with polyphenylsiloxane takes place in solution more deeply than under the conditions of mechanochemical activation and is accompanied by the process of separation siloxanes connection. This leads to the formation of a fraction with smaller ratio of substances than the initial ratio. 相似文献