全文获取类型
收费全文 | 128545篇 |
免费 | 8960篇 |
国内免费 | 3252篇 |
专业分类
电工技术 | 5088篇 |
技术理论 | 6篇 |
综合类 | 4977篇 |
化学工业 | 24074篇 |
金属工艺 | 6405篇 |
机械仪表 | 8404篇 |
建筑科学 | 6777篇 |
矿业工程 | 2609篇 |
能源动力 | 4560篇 |
轻工业 | 9175篇 |
水利工程 | 1409篇 |
石油天然气 | 5678篇 |
武器工业 | 525篇 |
无线电 | 16083篇 |
一般工业技术 | 20661篇 |
冶金工业 | 8082篇 |
原子能技术 | 1505篇 |
自动化技术 | 14739篇 |
出版年
2024年 | 368篇 |
2023年 | 1907篇 |
2022年 | 3142篇 |
2021年 | 4584篇 |
2020年 | 3433篇 |
2019年 | 3292篇 |
2018年 | 3853篇 |
2017年 | 4066篇 |
2016年 | 4008篇 |
2015年 | 4195篇 |
2014年 | 5840篇 |
2013年 | 7608篇 |
2012年 | 7967篇 |
2011年 | 9174篇 |
2010年 | 7419篇 |
2009年 | 7224篇 |
2008年 | 7023篇 |
2007年 | 6263篇 |
2006年 | 6126篇 |
2005年 | 5497篇 |
2004年 | 4057篇 |
2003年 | 3790篇 |
2002年 | 3422篇 |
2001年 | 2995篇 |
2000年 | 2957篇 |
1999年 | 3114篇 |
1998年 | 3425篇 |
1997年 | 2506篇 |
1996年 | 2261篇 |
1995年 | 1811篇 |
1994年 | 1474篇 |
1993年 | 1169篇 |
1992年 | 873篇 |
1991年 | 719篇 |
1990年 | 606篇 |
1989年 | 512篇 |
1988年 | 442篇 |
1987年 | 314篇 |
1986年 | 242篇 |
1985年 | 210篇 |
1984年 | 168篇 |
1983年 | 112篇 |
1982年 | 87篇 |
1981年 | 80篇 |
1980年 | 60篇 |
1979年 | 47篇 |
1978年 | 36篇 |
1977年 | 47篇 |
1976年 | 71篇 |
1975年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
141.
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
142.
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
143.
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
144.
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
145.
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
146.
Fenton氧化法去除酱油生产废水中焦糖色素的研究 总被引:1,自引:0,他引:1
着重考察了Fenton试剂对水中焦糖色素降解的影响因素.从试验中得出,这些影响因素包括pH、催化剂的投加方式、催化剂与氧化剂的化学计量数以及反应时间等.Fenton反应中,pH4的条件下处理效果最好,反应进行40min时去除率达到90%. 相似文献
147.
P. L. Sun E. K. Cerreta G. T. Gray III J. F. Bingert 《Metallurgical and Materials Transactions A》2006,37(10):2983-2994
Commercial purity aluminum AA1050 was subjected to equal channel angular extrusion (ECAE) that resulted in an ultrafine-grained
(UFG) microstructure with an as-received grain size of 0.35 μm. This UFG material was then annealed to obtain microstructures
with grain sizes ranging from 0.47 to 20 μm. Specimens were compressed at quasi-static, intermediate, and dynamic strain rates
at temperatures of 77 and 298 K. The mechanical properties were found to vary significantly with grain size, strain rate,
and temperature. Yield stress was found to increase with decreasing grain size, decreasing temperature, and increasing strain
rate. The work hardening rate was seen to increase with increasing grain size, decreasing temperature, and increasing strain
rate. The influence of strain rate and temperature is most significant in the smallest grain size specimens. The rate of work
hardening is also influenced by strain rate, temperature, and grain size with negative rates of work hardening observed at
298 K and quasi-static strain rates in the smallest grain sizes and increasing rates of work hardening with increasing loading
rate and grain size. Work hardening behavior is correlated with the substructural evolution of these specimens. 相似文献
148.
149.
150.
孙洪松 《石油化工管理干部学院学报》2006,(1):52-55
目前,我国股票市场上的股票评级尚处于探索阶段,评级时多采用专家法或历史法,而对于影响股票评级的各因素的确定以及因素间的相互作用缺乏定量分析。研究将结构模型应用到我国股票市场的股票评级中,建立关于我国股票评级的财务结构模型;分析各个因素对股票评级的影响;建立股票评级经验模式值。 相似文献