全文获取类型
收费全文 | 49375篇 |
免费 | 2756篇 |
国内免费 | 155篇 |
专业分类
电工技术 | 708篇 |
综合类 | 65篇 |
化学工业 | 10593篇 |
金属工艺 | 2136篇 |
机械仪表 | 3241篇 |
建筑科学 | 1099篇 |
矿业工程 | 25篇 |
能源动力 | 2111篇 |
轻工业 | 3887篇 |
水利工程 | 271篇 |
石油天然气 | 88篇 |
武器工业 | 2篇 |
无线电 | 7834篇 |
一般工业技术 | 10662篇 |
冶金工业 | 3881篇 |
原子能技术 | 658篇 |
自动化技术 | 5025篇 |
出版年
2024年 | 50篇 |
2023年 | 570篇 |
2022年 | 870篇 |
2021年 | 1483篇 |
2020年 | 1069篇 |
2019年 | 1176篇 |
2018年 | 1429篇 |
2017年 | 1411篇 |
2016年 | 1750篇 |
2015年 | 1294篇 |
2014年 | 2088篇 |
2013年 | 3006篇 |
2012年 | 3265篇 |
2011年 | 3889篇 |
2010年 | 2814篇 |
2009年 | 2921篇 |
2008年 | 2811篇 |
2007年 | 2185篇 |
2006年 | 2031篇 |
2005年 | 1723篇 |
2004年 | 1571篇 |
2003年 | 1513篇 |
2002年 | 1329篇 |
2001年 | 1134篇 |
2000年 | 996篇 |
1999年 | 928篇 |
1998年 | 1557篇 |
1997年 | 991篇 |
1996年 | 803篇 |
1995年 | 557篇 |
1994年 | 461篇 |
1993年 | 406篇 |
1992年 | 290篇 |
1991年 | 274篇 |
1990年 | 258篇 |
1989年 | 241篇 |
1988年 | 205篇 |
1987年 | 168篇 |
1986年 | 119篇 |
1985年 | 115篇 |
1984年 | 92篇 |
1983年 | 63篇 |
1982年 | 38篇 |
1981年 | 39篇 |
1980年 | 30篇 |
1979年 | 31篇 |
1978年 | 30篇 |
1977年 | 38篇 |
1976年 | 61篇 |
1973年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
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
63.
64.
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
65.
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
66.
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
67.
Dong‐Wook Kim 《ETRI Journal》2006,28(1):84-86
This letter presents a small‐sized, high‐power single‐pole double‐throw (SPDT) switch with defected ground structure (DGS) for wireless broadband Internet application. To reduce the circuit size by using a slow‐wave characteristic, the DGS is used for the quarter‐wave (°/4) transmission line of the switch. To secure a high degree of isolation, the switch with DGS is composed of shunt‐connected PIN diodes. It shows an insertion loss of 0.8 dB, an isolation of 50 dB or more, and power capability of at least 50 W at 2.3 GHz. The switch shows very similar performance to the conventional shunt‐type switch, but the circuit size is reduced by about 50% simply with the use of DGS patterns. 相似文献
68.
S H Lee J H Ko J R Kim Y J Kim J J Lee C W Kim T H Lee 《Water science and technology》2006,53(4-5):115-123
The adverse effect of nitrate on the phosphate release rate in the anaerobic phase was observed and was hardly explainable with conventional EBPR process models. Four possible mechanisms were proposed including substrate competition, reduced fermentation, parallel reaction and sequential reaction. Batch experiments were designed and conducted to identify the dominant mechanism. Results showed that the sequential reaction was the only possible mechanism where only denitrification occurred if any nitrate existed in the anaerobic phase. Then the phosphate release following after the nitrate was completely removed. Nitrate inhibition effect was added into the PHA storage rate to incorporate the sequential reaction in the conventional ASM3 plus EAWAG bio-P module (ASM3 + P). Nitrate inhibition coefficient, K(I,NO,PAO) was found to be as low as 0.05 mg/L. This correlated well with experimental observation where no also meant that the anaerobic compartment of a continuous flow reactor could be seriously affected by the residual nitrate contained in the sludge recycle flow. This phenomenon caused overestimation of the phosphate uptake rate and consequently underestimation of PO4(3-) -P concentration. This problem was resolved by incorporation of a nitrate inhibition term in the ASM3 + P for more accurate simulation of the EBPR process. 相似文献
69.
Namyong Kim 《ETRI Journal》2006,28(2):155-161
In this paper, we introduce an escalator (ESC) algorithm based on the least squares (LS) criterion. The proposed algorithm is relatively insensitive to the eigenvalue spread ratio (ESR) of an input signal and has a faster convergence speed than the conventional ESC algorithms. This algorithm exploits the fast adaptation ability of least squares methods and the orthogonalization property of the ESC structure. From the simulation results, the proposed algorithm shows superior convergence performance. 相似文献
70.
Flotation is a water treatment alternative to sedimentation, and uses small bubbles to remove low-density particles from potable water and wastewater. The effect of zeta potential, bubble size and particle size on removal efficiency of the electro-flotation process was investigated because previous model-simulations indicated that these attributes are critical for high collision efficiency between micro-bubbles and particles. Solutions containing Al3+ as the metal ion were subjected to various conditions. The zeta potentials of bubbles and particles were similar under identical conditions, and their charges were influenced by metal ion concentration and pH. Maximum removal efficiency was 98 and 12% in the presence and absence of flocculation, respectively. Removal efficiency was higher when particle size was similar to bubble size. These results agree with modelling simulations and indicate that collision efficiency is greater when the zeta potential of one is negative and that of the other is positive and when their sizes are similar. 相似文献