全文获取类型
收费全文 | 75783篇 |
免费 | 926篇 |
国内免费 | 731篇 |
专业分类
电工技术 | 1449篇 |
综合类 | 93篇 |
化学工业 | 11398篇 |
金属工艺 | 3511篇 |
机械仪表 | 2715篇 |
建筑科学 | 1712篇 |
矿业工程 | 531篇 |
能源动力 | 1910篇 |
轻工业 | 6465篇 |
水利工程 | 870篇 |
石油天然气 | 2332篇 |
武器工业 | 41篇 |
无线电 | 7350篇 |
一般工业技术 | 16578篇 |
冶金工业 | 12463篇 |
原子能技术 | 2657篇 |
自动化技术 | 5365篇 |
出版年
2022年 | 616篇 |
2021年 | 952篇 |
2020年 | 736篇 |
2019年 | 808篇 |
2018年 | 1591篇 |
2017年 | 1595篇 |
2016年 | 1803篇 |
2015年 | 985篇 |
2014年 | 1613篇 |
2013年 | 3640篇 |
2012年 | 2428篇 |
2011年 | 2904篇 |
2010年 | 2432篇 |
2009年 | 2710篇 |
2008年 | 2679篇 |
2007年 | 2585篇 |
2006年 | 2215篇 |
2005年 | 1950篇 |
2004年 | 1884篇 |
2003年 | 1835篇 |
2002年 | 1770篇 |
2001年 | 1734篇 |
2000年 | 1697篇 |
1999年 | 1581篇 |
1998年 | 3685篇 |
1997年 | 2613篇 |
1996年 | 1939篇 |
1995年 | 1525篇 |
1994年 | 1331篇 |
1993年 | 1353篇 |
1992年 | 997篇 |
1991年 | 1053篇 |
1990年 | 1072篇 |
1989年 | 1053篇 |
1988年 | 942篇 |
1987年 | 877篇 |
1986年 | 878篇 |
1985年 | 935篇 |
1984年 | 778篇 |
1983年 | 768篇 |
1982年 | 675篇 |
1981年 | 691篇 |
1980年 | 661篇 |
1979年 | 647篇 |
1978年 | 620篇 |
1977年 | 774篇 |
1976年 | 933篇 |
1975年 | 583篇 |
1974年 | 551篇 |
1973年 | 545篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Technical Physics Letters - Using the method of DC magnetron sputtering, nonstructured amorphous metal coatings of Zr75Pd25 composition were obtained with an average deposition rate of 1.3 nm/s at... 相似文献
63.
64.
N. Bartsch M. Girard A. Wilde T. Bruhn O. Kappenstein B. Vieth C. Hutzler A. Luch 《乙烯基与添加剂工艺杂志》2019,25(Z2):E12-E27
The thermo‐oxidative stability of widely used polymer additives has been investigated. A comparative analytical approach with classic and innovative decomposition models for polymer additives was conducted and the results supported using quantum‐chemical calculations. Unique pyrolysis products of the analytes were compiled utilizing pyrolysis online coupled to gas chromatography followed by mass spectrometric detection (Pyr‐GC–MS). The pyrolysis was either performed under inert conditions or in an oxygen‐containing atmosphere. Squalane was applied as polymer‐mimicking liquid next to low density polyethylene (LDPE) and polyamide 6 (PA 6) as matrices for 10 selected additives. The additives included in this study range from antioxidants and plasticizers to processing aids. These were selected to address a range of application in consumer products and to cover different chemical classes. The toxicological relevance of additives and potential breakdown products was considered. Consequently, degradation of sterically hindered antioxidants, diarylamines, and a trimellitic acid derivative was investigated. The findings were used to predict the behavior of consumer products made of polymeric materials entailing additives. The level of Antioxidant 2246 [2‐tert‐butyl‐6‐[(3‐tert‐butyl‐2‐hydroxy‐5‐methylphenyl)methyl]‐4‐methylphenol] and one of its predicted decomposition products was determined in baby bottle nipples made of natural rubber [2‐tert‐butyl‐4‐methylphenol] utilizing the complementary technique of gas chromatography coupled to tandem mass spectrometry (GC–MS/MS). This study provides a comprehensive characterization of important polymer additives and enables the prioritization of degradation products for further risk assessment. J. VINYL ADDIT. TECHNOL., 25:E12–E27, 2019. © 2018 The Authors. Journal of Vinyl and Additive Technology published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers 相似文献
65.
66.
67.
D. A. Mirzaev N. I. Vorob’ev O. K. Tokovi D. V. Shaburov E. A. Fominykh 《Russian Metallurgy (Metally)》2006,(1):38-41
The solutions to a differential equation for the problem of heating of a cylinder in a medium with a fixed temperature are used to obtain equations for estimating the change in the hydrogen concentration in forgings from data on the hydrogen concentration at the cylinder axis or on the average bulk hydrogen concentration. Similar equations are also obtained for forgings having square cross sections. The calculation demonstrates that, for the case of a twofold decrease in the hydrogen concentration in a forging, the calculated times of annealing of a cylindrical forging differ by three times. 相似文献
68.
Effendi Rusli Timothy O. Drews David L. Ma Richard C. Alkire Richard D. Braatz 《Journal of Process Control》2006,16(4):409-417
Robust nonlinear feedforward–feedback controllers are designed for a multiscale system that dynamically couples kinetic Monte Carlo (KMC) and finite difference (FD) simulation codes. The coupled codes simulate the copper electrodeposition process for manufacturing on-chip copper interconnects in electronic devices. The control objective is to regulate the current density subject to the condition that the steady-state fluctuation of the overpotential remains bounded within ±0.01 V. The controller designs incorporate a low-order stochastic model that captures the input–output behavior of the coupled KMC–FD code. The controllers achieve the objectives and the closed-loop responses implemented on the low-order model and the coupled KMC–FD code match well within stochastic variations. The nonlinear feedforward control reduces the rise time of the controller response while the feedback control ensures robustness in the presence of model uncertainty. 相似文献
69.
The Magnitogorsk Metallurgical Combine has conducted a study of the effect of technological factors on the hydrogen content
of chromium-nickel-molybdenum steel after vacuum degassing. It was established that the most important factor is the hydrogen
content of the steel before the degassing operation. The study also determined the effects of the circulation coefficient,
the duration of the degassing operation, and the vacuum used in the treatment.
__________
Translated from Metallurg, No. 7, pp. 68–69, July, 2006. 相似文献
70.
Breakdown of a company is examined and the concept of its stability is given. A system of indexes for characterizing the market position of an enterprise in the chemical industry and predicting its dynamics is proposed. An integral index can be an effective tool in the hands of managers in making managerial decisions related to effectively reacting to changes in the company's market position. 相似文献