全文获取类型
收费全文 | 52438篇 |
免费 | 3087篇 |
国内免费 | 160篇 |
专业分类
电工技术 | 752篇 |
综合类 | 67篇 |
化学工业 | 11348篇 |
金属工艺 | 2238篇 |
机械仪表 | 3465篇 |
建筑科学 | 1147篇 |
矿业工程 | 25篇 |
能源动力 | 2299篇 |
轻工业 | 4192篇 |
水利工程 | 276篇 |
石油天然气 | 90篇 |
武器工业 | 2篇 |
无线电 | 8331篇 |
一般工业技术 | 11391篇 |
冶金工业 | 4027篇 |
原子能技术 | 709篇 |
自动化技术 | 5326篇 |
出版年
2024年 | 24篇 |
2023年 | 569篇 |
2022年 | 716篇 |
2021年 | 1556篇 |
2020年 | 1144篇 |
2019年 | 1266篇 |
2018年 | 1564篇 |
2017年 | 1525篇 |
2016年 | 1907篇 |
2015年 | 1434篇 |
2014年 | 2270篇 |
2013年 | 3271篇 |
2012年 | 3496篇 |
2011年 | 4182篇 |
2010年 | 3033篇 |
2009年 | 3133篇 |
2008年 | 2987篇 |
2007年 | 2341篇 |
2006年 | 2154篇 |
2005年 | 1826篇 |
2004年 | 1684篇 |
2003年 | 1617篇 |
2002年 | 1433篇 |
2001年 | 1219篇 |
2000年 | 1075篇 |
1999年 | 1005篇 |
1998年 | 1630篇 |
1997年 | 1023篇 |
1996年 | 831篇 |
1995年 | 585篇 |
1994年 | 478篇 |
1993年 | 419篇 |
1992年 | 305篇 |
1991年 | 281篇 |
1990年 | 272篇 |
1989年 | 256篇 |
1988年 | 209篇 |
1987年 | 170篇 |
1986年 | 125篇 |
1985年 | 119篇 |
1984年 | 96篇 |
1983年 | 63篇 |
1982年 | 38篇 |
1981年 | 40篇 |
1980年 | 30篇 |
1979年 | 33篇 |
1978年 | 30篇 |
1977年 | 40篇 |
1976年 | 65篇 |
1975年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
Seung Han Ryu Seil Kim Young-Tae Kwon Young Ki Park Sung-Oong Kang Hong-Baek Cho Yong-Ho Choa 《应用聚合物科学杂志》2020,137(8):48390
Here, we report a facile approach to electrostatically couple the surface charges of graphite nanoplate (GNP) fillers and poly(methyl methacrylate) (PMMA) polymer particles using ethylene maleic anhydride (EMA) copolymer as an electrostatic coupling agent. Our strategy involved switching the intrinsic repulsive electrostatic interactions between the directly exfoliated GNPs fillers and the PMMA particles to attractive electrostatic surface interactions for preparing core(PMMA)-shell (GNP) precursor in order to optimizing 3-dimensionally dispersed polymer nanocomposite. As a result, the electrical conductivity of the composites dramatically increased by a factor of 16.7 in the EMA-coupled GNP/PMMA composites compared with that of the EMA-free GNP/PMMA composites. In addition, the percolation threshold was also notably reduced from 0.32 to 0.159 vol% after electrostatic coupling of the GNPs fillers and PMMA particles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48390. 相似文献
62.
Park Sangwon Nam Hyunbin Na Youngsang Kim Hyoungseop Moon Younghoon Kang Namhyun 《Metals and Materials International》2020,26(5):641-649
Metals and Materials International - This study investigated the influence of the initial grain size on the plastic deformation and tunnel defects that occurred from friction stir welding of... 相似文献
63.
64.
Kim Geonu Kacar Yilmaz Pistorius Petrus Christiaan 《Metallurgical and Materials Transactions B》2019,50(6):2508-2516
Metallurgical and Materials Transactions B - The concentration and chemical bonding state of carbon in direct-reduced iron (DRI) might affect DRI melting temperature and rate. The effects of carbon... 相似文献
65.
Seong‐Hee Kim 《Quality and Reliability Engineering International》2015,31(6):923-934
We present a distribution‐free tabular cumulative sum chart for monitoring the variability of an autocorrelated process. A quantity known as the asymptotic variance parameter is employed as a measure of the variability, and a distribution‐free tabular cumulative sum chart is applied to variance estimates calculated from batches of nonoverlapping samples. The proposed chart is applicable to a stationary process with a general marginal distribution and a general autocorrelation structure. It also determines control limits analytically without trial‐and‐error simulations. The performance of the proposed chart is tested on stationary processes with both normal and nonnormal marginals with various autocorrelation structures. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
66.
67.
Oh Seung-Jun Yoon Jeong-Hwan Kim Si-Pom 《Journal of Mechanical Science and Technology》2021,35(3):1065-1073
Journal of Mechanical Science and Technology - In the industry, globe valves, which are commonly used to precise control the flow rate along with opening and closing flow in pipes, are technically... 相似文献
68.
Ha-Nul Lee Joo-Hee Choi Ji-Yeon Park Jae-Hun Ahn Da Eun Jang Jae Gun Shim Jong-Hwan Park Young-Min Kim 《Food science and biotechnology》2021,30(4):583
Vegetable soup (VS), a plant-based functional food, has been used as a traditional folk medicine and is attracting attention for its ability to enhance the immune response. β-Glucan, a well-established and effective immunomodulator, has synergistic effects when used in combination with some bioactive compounds. In the present study, we aimed to evaluate the synergistic immunomodulatory effects of the combination of VS and β-glucan on macrophage-mediated immune responses. β-Glucan was demonstrated to synergistically enhance the VS-stimulated immune response, including the production of interleukin-6, tumor necrosis factor-α, and nitric oxide, mainly through the mitogen-activated protein kinase pathway in macrophages. In addition, this combination has the potential for further development in functional foods with immune-enhancing activity.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10068-021-00888-x. 相似文献
69.
Food Science and Biotechnology - St. Paul’s Wort (Siegesbeckia orientalis L.) confers anti-oxidative, anti-inflammatory, anti-allergic, anti-infertility, and immunosuppressive properties.... 相似文献
70.
Toshihiko Kujime Soong-Keun Hyun Hideo Nakajima 《Metallurgical and Materials Transactions A》2006,37(2):393-398
A lotus-type porous carbon steel with cylindrical pores was fabricated by the continuous zone melting method in a pressurized
mixture of hydrogen and helium gases. The porosity increases with increasing partial pressure of the hydrogen gas, while the
pore diameter remains almost constant, independent of the pressure. The ultimate tensile strength of the specimen with cylindrical
pores parallel to the tensile direction is lower than the estimated value, assuming that the strength is decreased in proportion
to the decrease of the cross-sectional area of the specimen, while the yield strength is higher than the estimated value.
The compressive yield strength is also higher than the estimated value. The increase in yield strength is considered to be
due to precipitation strengthening. The tensile strength is increased by quenching and tempering, while the elongation decreases.
Such mechanical properties are discussed in terms of the microstructural analysis. 相似文献