全文获取类型
收费全文 | 2923篇 |
免费 | 155篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 51篇 |
综合类 | 18篇 |
化学工业 | 673篇 |
金属工艺 | 66篇 |
机械仪表 | 44篇 |
建筑科学 | 92篇 |
矿业工程 | 7篇 |
能源动力 | 77篇 |
轻工业 | 351篇 |
水利工程 | 33篇 |
石油天然气 | 25篇 |
武器工业 | 2篇 |
无线电 | 280篇 |
一般工业技术 | 357篇 |
冶金工业 | 589篇 |
原子能技术 | 14篇 |
自动化技术 | 422篇 |
出版年
2023年 | 18篇 |
2022年 | 54篇 |
2021年 | 103篇 |
2020年 | 64篇 |
2019年 | 52篇 |
2018年 | 76篇 |
2017年 | 76篇 |
2016年 | 66篇 |
2015年 | 68篇 |
2014年 | 83篇 |
2013年 | 176篇 |
2012年 | 108篇 |
2011年 | 157篇 |
2010年 | 130篇 |
2009年 | 128篇 |
2008年 | 124篇 |
2007年 | 132篇 |
2006年 | 106篇 |
2005年 | 83篇 |
2004年 | 84篇 |
2003年 | 97篇 |
2002年 | 81篇 |
2001年 | 60篇 |
2000年 | 51篇 |
1999年 | 41篇 |
1998年 | 190篇 |
1997年 | 122篇 |
1996年 | 109篇 |
1995年 | 68篇 |
1994年 | 48篇 |
1993年 | 60篇 |
1992年 | 20篇 |
1991年 | 23篇 |
1990年 | 18篇 |
1989年 | 15篇 |
1988年 | 12篇 |
1987年 | 17篇 |
1986年 | 16篇 |
1985年 | 13篇 |
1984年 | 7篇 |
1983年 | 9篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1979年 | 13篇 |
1978年 | 8篇 |
1977年 | 16篇 |
1976年 | 30篇 |
1975年 | 6篇 |
1971年 | 7篇 |
排序方式: 共有3101条查询结果,搜索用时 31 毫秒
1.
Optimization and Engineering - 相似文献
2.
Peng Li Haibin Jiang Ariel Barr Zhichu Ren Rui Gao Hua Wang Weiwei Fan Meifang Zhu Guiyin Xu Ju Li 《Advanced functional materials》2021,31(51):2105845
Mercury, lead, and cadmium are among the most toxic and carcinogenic heavy metal ions (HMIs), posing serious threats to the sustainability of aquatic ecosystems and public health. There is an urgent need to remove these ions from water by a cheap but green process. Traditional methods have insufficient removal efficiency and reusability. Structurally robust, large surface-area adsorbents functionalized with high-selectivity affinity to HMIs are attractive filter materials. Here, an adsorbent prepared by vulcanization of polyacrylonitrile (PAN), a nitrogen-rich polymer, is reported, giving rise to PAN-S nanoparticles with cyclic π-conjugated backbone and electronic conductivity. PAN-S can be coated on ultra-robust melamine (ML) foam by simple dipping and drying. In agreement with hard/soft acid/base theory, N- and S-containing soft Lewis bases have strong binding to Hg2+, Pb2+, Cu2+, and Cd2+, with extraordinary capture efficiency and performance stability. Furthermore, the used filters, when collected and electrochemically biased in a recycling bath, can release the HMIs into the bath and electrodeposit on the counter-electrode as metallic Hg0, Pb0, Cu0, and Cd0, and the PAN-S@ML filter can then be reused at least 6 times as new. The electronically conductive PAN-S@ML filter can be fabricated cheaply and holds promise for scale-up applications. 相似文献
3.
Laís D. Silva Fernanda C. Puosso Viviane O. Soares Oscar Peitl Filho Simone do R.F. Sabino Francisco C. Serbena Murilo C. Crovace Edgar D. Zanotto 《Ceramics International》2021,47(13):18720-18731
Bioactive glasses and glass-ceramics (GCs) effectively regenerate bone tissue, however most GCs show improved mechanical properties. In this work, we developed and tested a rarely studied bioactive glass composition (24.4K2O-26.9CaO-46.1SiO2-2.6P2O5 mol%, identified as 45S5-K) with different particle sizes and heating rates to obtain a sintered GC that combines good fracture strength, low elastic modulus, and bioactivity. We analyzed the influence of the sintering processing conditions in the elastic modulus, Vickers microhardness, density, and crystal phase formation in the GC. The best GC shows improved properties compared with its parent glass. This glass achieves a good densification degree with a two-step viscous flow sintering approach and the resulting GC shows as high bioactivity as that of the standard 45S5 Bioglass®. Furthermore, the GC elastic modulus (56 GPa) is relatively low, minimizing stress shielding. Therefore, we unveiled the glass sintering behavior with concurrent crystallization of this complex bioactive glass composition and developed a potential GC for bone regeneration. 相似文献
4.
Stefano Mariani Antonino Amedeo La Mattina Alessandro Paghi Lucanos Strambini Giuseppe Barillaro 《Advanced functional materials》2021,31(26):2100774
Here, a fluoride-assisted route for the controlled in-situ synthesis of metal nanoparticles (NPs) (i.e., AgNPs, AuNPs) on polydimethylsiloxane (PDMS) is reported. The size and coverage of the NPs on the PDMS surface are modulated with time and over space during the synthetic process, leveraging the improved yield (10×) and faster kinetics (100×) of NP formation in the presence of F− ions, compared to fluoride-free approaches. This enables the maskless preparation of both linear and step gradients and patterns of NPs in 1D and 2D on the PDMS surface. As an application in flexible plasmonics/photonics, continuous and step-wise spatial modulations of the plasmonic features of PDMS slabs with 1D and 2D AgNP gradients on the surface are demonstrated. An excellent spatially resolved tuning of key optical parameters, namely, optical density from zero to 5 and extinction ratio up to 100 dB, is achieved with AgNP gradients prepared in AgF solution for 12 minutes; the performance are comparable to those of commercial dielectric/interference filters. When used as a rejection filter in optical fluorescence microscopy, the AgNP-PDMS slabs are able to reject the excitation laser at 405 nm and retain the green fluorescence of microbeads (100 µm) used as test cases. 相似文献
5.
6.
Lydia Saidi Dr. Djenisa H. A. Rocha Dr. Oualid Talhi Dr. Yamina Bentarzi Prof. Dr. Bellara Nedjar-Kolli Dr. Khaldoun Bachari Dr. Filipe A. Almeida Paz Dr. Luisa A. Helguero Prof. Dr. Artur M. S. Silva 《ChemMedChem》2019,14(10):1041-1048
Breast and prostate cancers are frequently treated with chemotherapy. Several novel chemicals are being reported for this purpose, particularly synthetic and natural benzophenones. This work reports the synthesis of substituted 2-hydroxybenzophenones through 1,4-conjugate addition/intramolecular cycloaddition/dehydration of nitromethane on key intermediate chromones. Structures were extensively studied by means of 2D NMR spectroscopy and single-crystal XRD. Their cytotoxicity was evaluated in vitro in two breast cancer cell lines (MDA-MB-231 and T47-D) and one prostate cancer cell line (PC3). The most potent compound exhibited good cytotoxic effects against the three cancer cell lines (IC50 values ranging from 12.09 to 26.49 μm ) and induced cell-cycle retardation only on prostate cancer cells, which suggested that it might exert cell-type-specific effects. 相似文献
7.
Maria Grazia Basanisi Gianfranco La Bella Gaia Nobili Rosa Coppola Annita Maria Damato Maria Assunta Cafiero Giovanna La Salandra 《International Journal of Food Science & Technology》2020,55(3):1145-1150
The authenticity and traceability of meat products are issues of primary importance to ensure food safety. Unfortunately, food adulteration (e.g. the addition of inexpensive cuts to minced meat products) and mislabelling (e.g. the inclusion of meat from species other than those declared) happens frequently worldwide. The aim of this study was to apply a droplet digital PCR assay for the detection and quantification (copies μL−1) of the beef, pork, horse, sheep, chicken and turkey in meat products. The analysis conducted on commercial meat showed the presence of traces of DNA from other animal species than those declared. We show that the method is highly sensitive, specific and accurate (accuracy = 100%). This method could be adopted by competent food safety authorities to verify compliance with the labelling of meat products and to ensure quality and safety throughout the meat supply chain, from primary production to consumption. 相似文献
8.
9.
10.
E La Hey J de Vries CT Langerhorst GS Baarsma A Kijlstra 《Canadian Metallurgical Quarterly》1993,116(3):327-340
After reviewing the records of 111 patients with Fuchs' heterochromic iridocyclitis, we studied the therapy and prognosis of secondary glaucoma in 30 of these 111 patients (27%) who had glaucoma or could be considered glaucoma suspects. Maximal medical therapy was unsuccessful in 22 of the 30 patients (73%). Surgical intervention (mostly trabeculectomies, half with 5-fluorouracil) successfully controlled intraocular pressure (< or = 21 mm Hg with or without medication) in 13 of the 18 operated-on patients (72%) after a mean follow-up of 26 months. All successfully operated-on patients retained a visual acuity of 20/80 or better. We had favorable results, possibly because of modern surgical techniques (use of 5-fluorouracil, sodium hyaluronate) or earlier surgical intervention, or both. 相似文献