全文获取类型
收费全文 | 391763篇 |
免费 | 4726篇 |
国内免费 | 1233篇 |
专业分类
电工技术 | 7150篇 |
综合类 | 2659篇 |
化学工业 | 53888篇 |
金属工艺 | 19604篇 |
机械仪表 | 16253篇 |
建筑科学 | 9140篇 |
矿业工程 | 2268篇 |
能源动力 | 8008篇 |
轻工业 | 26646篇 |
水利工程 | 4437篇 |
石油天然气 | 5481篇 |
武器工业 | 68篇 |
无线电 | 48152篇 |
一般工业技术 | 79633篇 |
冶金工业 | 53510篇 |
原子能技术 | 6533篇 |
自动化技术 | 54292篇 |
出版年
2021年 | 2091篇 |
2019年 | 2094篇 |
2018年 | 22558篇 |
2017年 | 22218篇 |
2016年 | 15998篇 |
2015年 | 3332篇 |
2014年 | 4418篇 |
2013年 | 11660篇 |
2012年 | 11350篇 |
2011年 | 23757篇 |
2010年 | 20568篇 |
2009年 | 18501篇 |
2008年 | 19780篇 |
2007年 | 22218篇 |
2006年 | 8085篇 |
2005年 | 11374篇 |
2004年 | 9520篇 |
2003年 | 9108篇 |
2002年 | 7439篇 |
2001年 | 6646篇 |
2000年 | 6454篇 |
1999年 | 6353篇 |
1998年 | 14316篇 |
1997年 | 10319篇 |
1996年 | 8172篇 |
1995年 | 6439篇 |
1994年 | 5747篇 |
1993年 | 5620篇 |
1992年 | 4575篇 |
1991年 | 4256篇 |
1990年 | 4056篇 |
1989年 | 3785篇 |
1988年 | 3634篇 |
1987年 | 3173篇 |
1986年 | 3068篇 |
1985年 | 3613篇 |
1984年 | 3384篇 |
1983年 | 3031篇 |
1982年 | 2853篇 |
1981年 | 2953篇 |
1980年 | 2762篇 |
1979年 | 2650篇 |
1978年 | 2500篇 |
1977年 | 2946篇 |
1976年 | 3556篇 |
1975年 | 2317篇 |
1974年 | 2312篇 |
1973年 | 2318篇 |
1972年 | 1850篇 |
1971年 | 1745篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
Cerebral microbleeds and cognitive decline in a hemodialysis patient: Case report and review of literature 下载免费PDF全文
Lin Li Mark Fisher Wei‐Ling Lau Hamid Moradi Alexander Cheung Gaby Thai Jason Handwerker Kamyar Kalantar‐Zadeh 《Hemodialysis international. International Symposium on Home Hemodialysis》2015,19(3):E1-E7
Cerebral microbleeds (CMBs) are small hemosiderin deposits indicative of prior cerebral microscopic hemorrhage and previously thought to be clinically silent. Recent population‐based cross‐sectional studies and prospective longitudinal cohort studies have revealed association between CMB and cognitive dysfunction. In the general population, CMBs are associated with age, hypertension, and cerebral amyloid angiopathy. In the chronic kidney disease (CKD) population, diminished estimated glomerular filtration rate has been found to be an independent risk factor for CMB, raising the possibility that a uremic milieu may predispose to microbleeds. In the end‐stage renal disease (ESRD) population on hemodialysis, the incidence of microbleeds is significantly higher compared with a control group without history of CKD or stroke. We present an ESRD patient on chronic hemodialysis with a history of gradual cognitive decline and progressive CMBs. Through this case and literature review, we illustrate the need to develop detection and prediction models to treat this frequent development in ESRD patients. 相似文献
62.
63.
64.
An alternative Equivalent Electrical Circuit for Proton Exchange Membrane Fuel Cells is modelled in this study. Both I–V characteristics and H2 consumptions corresponding to generated power under load and no-load conditions are investigated. For this purpose, H2 consumptions and I–V characteristics of three different sized PEMFCs are tested. There is a very good harmony between the model results and measured values (relative error %0.7, %6.4 and %2.5 for FC-A, FC-B and FC-C respectively). In the proposed model current passes only on parallel resistance and not on serial resistance at no-load condition. Thus, a FC with higher parallel resistance should be preferred. Another key output of this study is that based on the proposed model, performance comparison of FCs can be performed with the parameters defined in this work. Proposals made in this study can easily be used for performance analysis of FCs under for both steady state and transient analysis. 相似文献
65.
Hammons Joshua A. Tumey Scott J. Idell Yaakov Jeffries Jason R. 《JOM Journal of the Minerals, Metals and Materials Society》2020,72(1):176-186
JOM - Alpha-radiation damage in metals is a concern for long-term radioactive storage and systems that produce nuclear energy. Accurate prediction of irradiated material properties and failure... 相似文献
66.
Zakaryan D. A. Kartuzov V. V. Khachatryan A. V. 《Powder Metallurgy and Metal Ceramics》2015,54(3-4):210-214
Powder Metallurgy and Metal Ceramics - The theoretical strength of LaB6 and MeB2 borides and a eutectic LaB6–TiB2 system is calculated with quasiharmonic approximation for uniaxial strain in... 相似文献
67.
68.
V. I. Zubkov O. V. Kucherova I. N. Yakovlev A. V. Solomonov 《Russian Microelectronics》2015,44(3):203-209
An automated system for integrated electrophysical and optical studies of semiconductor nanoheterostructures, which operates in a wide temperature range from 15 to 475 K, is designed. The setup is intended to measure the temperature and frequency admittance and electroluminescence spectra of light-emitting diode and laser chips formed on substrates of diameter up to 50.2 mm, and the distribution of parameters over the wafer. The setup includes the closed-cycle helium cryogenic station, LCR meter, and temperature controller. The characterization results of nanoheterostructures with InGaN/GaN multiple quantum wells, which are used for creating highly efficient white and blue light-emitting diodes, are presented. 相似文献
69.
I. N. Andronov Yu. I. Ryabkov N. P. Bogdanov N. A. Severova A. N. Danilov I. V. Churilina 《Russian Metallurgy (Metally)》2015,2015(10):778-784
The influence of the thermal cycling conditions on the thermal-cycling creep of a TN-1 alloy and the related irreversible deformations is studied. The conditions under which an anomalous increase in the irreversible deformations begins are determined. The structural mechanism of the irreversible deformations of an equiatomic alloy is shown to be analogous to the structural mechanism of metal creep at high temperatures: it predominantly has a dislocation character. It is proposed to use the effect of anomalous increase in the deformation of materials with reversible martensitic transformations for forming parts made of these materials at low temperatures. 相似文献
70.