全文获取类型
收费全文 | 695437篇 |
免费 | 4779篇 |
国内免费 | 1088篇 |
专业分类
电工技术 | 12415篇 |
综合类 | 571篇 |
化学工业 | 110039篇 |
金属工艺 | 30545篇 |
机械仪表 | 22520篇 |
建筑科学 | 15286篇 |
矿业工程 | 6010篇 |
能源动力 | 17045篇 |
轻工业 | 52015篇 |
水利工程 | 9152篇 |
石油天然气 | 20082篇 |
武器工业 | 48篇 |
无线电 | 70670篇 |
一般工业技术 | 147279篇 |
冶金工业 | 112419篇 |
原子能技术 | 18919篇 |
自动化技术 | 56289篇 |
出版年
2021年 | 6862篇 |
2020年 | 5436篇 |
2019年 | 6866篇 |
2018年 | 11257篇 |
2017年 | 11438篇 |
2016年 | 12149篇 |
2015年 | 7337篇 |
2014年 | 12503篇 |
2013年 | 31253篇 |
2012年 | 19021篇 |
2011年 | 25302篇 |
2010年 | 20319篇 |
2009年 | 22712篇 |
2008年 | 23015篇 |
2007年 | 22578篇 |
2006年 | 19411篇 |
2005年 | 17505篇 |
2004年 | 16783篇 |
2003年 | 16451篇 |
2002年 | 15921篇 |
2001年 | 15381篇 |
2000年 | 14816篇 |
1999年 | 14335篇 |
1998年 | 32103篇 |
1997年 | 23527篇 |
1996年 | 18299篇 |
1995年 | 14148篇 |
1994年 | 12958篇 |
1993年 | 12688篇 |
1992年 | 9987篇 |
1991年 | 9816篇 |
1990年 | 9686篇 |
1989年 | 9380篇 |
1988年 | 9029篇 |
1987年 | 8335篇 |
1986年 | 8066篇 |
1985年 | 9024篇 |
1984年 | 8298篇 |
1983年 | 8029篇 |
1982年 | 7288篇 |
1981年 | 7440篇 |
1980年 | 7190篇 |
1979年 | 7406篇 |
1978年 | 7385篇 |
1977年 | 8043篇 |
1976年 | 9720篇 |
1975年 | 6669篇 |
1974年 | 6579篇 |
1973年 | 6646篇 |
1972年 | 5821篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
Deev V. B. Prusov E. S. Shurkin P. K. Ri E. H. Smetanyuk S. V. 《Russian Journal of Non-Ferrous Metals》2021,62(4):424-430
Russian Journal of Non-Ferrous Metals - Using a Thermo-Calc software package (TCAl4.0 database), unexplored data concerning the phase composition and crystallization behavior of... 相似文献
192.
Baranov D. A. Zhatkin S. S. Nikitin V. I. Deev V. B. Nikitin K. V. Barinov A. Yu. Yudin D. M. 《Russian Journal of Non-Ferrous Metals》2021,62(4):441-447
Russian Journal of Non-Ferrous Metals - The process of making a weld using the heat-resistant EP693 alloy (Ni–Cr–W–Co–Co–Mo system) to make assemblies and components... 相似文献
193.
Deev V. B. Ri E. H. Prusov E. S. Ermakov M. A. Goncharov A. V. 《Russian Journal of Non-Ferrous Metals》2021,62(5):522-530
Russian Journal of Non-Ferrous Metals - In this paper, using the AA 511 alloy of the Al–Mg–Si system as an example, it is shown that the irradiation of aluminum melts with nanosecond... 相似文献
194.
Demirov A. P. Blinkov I. V. Kuznetsov D. V. Kuskov K. V. Kolesnikov E. A. Sedegov A. S. 《Russian Journal of Non-Ferrous Metals》2021,62(5):602-610
Russian Journal of Non-Ferrous Metals - This article discusses methods for producing a material with gradient multilevel porosity by sintering layer-by-layer distributed α-Fe2O3 nanopowders... 相似文献
195.
Russian Journal of Non-Ferrous Metals - Laser cladding, which is characterized by the minimal thermal impact on the substrate, is an advanced technique to restore the working dimensions of parts... 相似文献
196.
Sobol O.V. Gorban V.F. Krapivka N.A. Rogul T.G. Firstov S.A. 《Powder Metallurgy and Metal Ceramics》2021,59(11-12):715-721
Powder Metallurgy and Metal Ceramics - The phase composition, type II microstresses, and coherent scattering domains (CSDs) of multicomponent (medium- and high-entropy) bcc solid solutions with an... 相似文献
197.
Lysunenko N.O. Brodnikovskyi Y.M. Mokiichuk V.M. Polishko I.O. Brodnikovskyi D.M. Chedryk V.I. Vasylyev O.D. 《Powder Metallurgy and Metal Ceramics》2021,60(5-6):352-359
Powder Metallurgy and Metal Ceramics - Fuel cells are today among the most efficient and environmentally friendly devices for the production of electricity. They are developing rapidly and are... 相似文献
198.
Mohammed A. Rajeh John E. Tookey James Olabode Bamidele Rotimi 《Construction Management & Economics》2013,31(11-12):921-941
The choice of an appropriate procurement system is crucial to construction project success. Procurement selection is largely based on path determination charts, with at least eight key criteria needing to be weighted by decision-makers. Including certain criteria whilst ignoring client-borne transaction costs (TCs) resulting from environmental uncertainties simplifies this process. TCs are ‘unseen’ costs associated with pre- and post-contract work. The effects of uncertainties in the transaction environment and procurement systems on TCs are investigated, comparing the traditional and design-build procurement systems. A cross-sectional sample approach was deployed, involving survey questionnaire and results verification through ‘real-world’ cases. Data was sought from construction professionals in management, design and operation of construction projects. The research participants evaluate their time spent on procurement activities using a five-point Likert scale. Hypotheses of the relations between environmental uncertainties, procurement systems, and pre- and post-contract TCs are tested using a structural equation modelling (SEM) approach. The study found that TCs account for about 46.75% and 42.88% of the daily time spent by project managers in traditional and design-build procurement systems in New Zealand respectively. The study concludes that the TC concept is a useful framework for determining objective instead of subjective opinions for procurement decisions. 相似文献
199.
200.
I.P.L. Coleman J.A. Blair M.E. Hilburn 《The International journal of environmental studies》2013,70(3-4):187-191
The effect of a number of dietary and synthetic chelating agents on the intestinal absorption of lead has been examined using the everted sac preparation and the tracer isotope 203Pb. All the agents examined increased lead transport into the serosal compartment. An explanation of the way in which these agents modify the model to describe lead transport is proposed. 相似文献