全文获取类型
收费全文 | 55819篇 |
免费 | 3259篇 |
国内免费 | 161篇 |
专业分类
电工技术 | 805篇 |
综合类 | 75篇 |
化学工业 | 11824篇 |
金属工艺 | 2384篇 |
机械仪表 | 3605篇 |
建筑科学 | 1219篇 |
矿业工程 | 26篇 |
能源动力 | 2401篇 |
轻工业 | 4467篇 |
水利工程 | 299篇 |
石油天然气 | 92篇 |
武器工业 | 3篇 |
无线电 | 8889篇 |
一般工业技术 | 12129篇 |
冶金工业 | 4460篇 |
原子能技术 | 736篇 |
自动化技术 | 5825篇 |
出版年
2024年 | 27篇 |
2023年 | 603篇 |
2022年 | 587篇 |
2021年 | 1646篇 |
2020年 | 1213篇 |
2019年 | 1332篇 |
2018年 | 1655篇 |
2017年 | 1635篇 |
2016年 | 2036篇 |
2015年 | 1534篇 |
2014年 | 2415篇 |
2013年 | 3515篇 |
2012年 | 3708篇 |
2011年 | 4504篇 |
2010年 | 3239篇 |
2009年 | 3361篇 |
2008年 | 3131篇 |
2007年 | 2515篇 |
2006年 | 2296篇 |
2005年 | 1941篇 |
2004年 | 1790篇 |
2003年 | 1687篇 |
2002年 | 1495篇 |
2001年 | 1283篇 |
2000年 | 1155篇 |
1999年 | 1069篇 |
1998年 | 1770篇 |
1997年 | 1105篇 |
1996年 | 906篇 |
1995年 | 616篇 |
1994年 | 522篇 |
1993年 | 451篇 |
1992年 | 331篇 |
1991年 | 302篇 |
1990年 | 285篇 |
1989年 | 271篇 |
1988年 | 222篇 |
1987年 | 177篇 |
1986年 | 136篇 |
1985年 | 123篇 |
1984年 | 103篇 |
1983年 | 74篇 |
1982年 | 42篇 |
1981年 | 43篇 |
1980年 | 37篇 |
1979年 | 37篇 |
1978年 | 33篇 |
1977年 | 46篇 |
1976年 | 73篇 |
1973年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
71.
Inam Ridha Ali Basiri Sudhakar Godeshala Md Zubair Ebne Rafique Deepanjan Ghosh Jason Williams Nikhilesh Chawla Jung Keun Lee Jacquelyn Kilbourne Yu Yao Kaushal Rege 《Advanced functional materials》2021,31(6):2007811
Poor strength, infection, leakage, long procedure times, and inflammation limit the efficacy of common tissue sealing devices in surgeries and trauma. Light-activated sealing is attractive for tissue sealing and repair, and can be facilitated by the generation of local heat following absorption of nonionizing laser energy by chromophores. Here, the inherent ability of biomaterials is exploited to absorb nonionizing, mid-infrared (midIR) light in order to engender rapid photothermal sealing and repair of soft tissue wounds. In this approach, the biomaterial simultaneously acts as a photothermal convertor as well as a biosealant, which dispenses the need for exogeneous light-absorbing nanoparticles or dyes. Biomechanical recovery, mathematical modeling, histopathology analyses, tissue strain mapping using digital imaging correlation, and visualization of the biosealant-tissue interface using hyperspectral imaging indicate superior performance of midIR sealing in live mice compared to conventional sutures and glue. The midIR-biosealant approach demonstrates rapid sealing of soft tissues, improves cosmesis, lowers potential for scarring, obviates safety concerns because of the nonionizing light used, and allows adoption of a wide diversity of biomaterials. Taken together, the studies demonstrate a novel advance both in biomaterials for surgical sealing along with the use of nonionizing midIR light, with high potential for clinical translation. 相似文献
72.
73.
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
74.
Jinho Choi Sanghun Jung Deok Gun Park Jaegul Choo Niklas Elmqvist 《Computer Graphics Forum》2019,38(3):249-260
The majority of visualizations on the web are still stored as raster images, making them inaccessible to visually impaired users. We propose a deep‐neural‐network‐based approach that automatically recognizes key elements in a visualization, including a visualization type, graphical elements, labels, legends, and most importantly, the original data conveyed in the visualization. We leverage such extracted information to provide visually impaired people with the reading of the extracted information. Based on interviews with visually impaired users, we built a Google Chrome extension designed to work with screen reader software to automatically decode charts on a webpage using our pipeline. We compared the performance of the back‐end algorithm with existing methods and evaluated the utility using qualitative feedback from visually impaired users. 相似文献
75.
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
76.
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
77.
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
78.
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
79.
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
80.
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