全文获取类型
收费全文 | 281951篇 |
免费 | 8567篇 |
国内免费 | 3517篇 |
专业分类
电工技术 | 8348篇 |
技术理论 | 9篇 |
综合类 | 4748篇 |
化学工业 | 41969篇 |
金属工艺 | 11851篇 |
机械仪表 | 10644篇 |
建筑科学 | 10968篇 |
矿业工程 | 2707篇 |
能源动力 | 7088篇 |
轻工业 | 19215篇 |
水利工程 | 3124篇 |
石油天然气 | 7292篇 |
武器工业 | 495篇 |
无线电 | 37336篇 |
一般工业技术 | 48267篇 |
冶金工业 | 49812篇 |
原子能技术 | 4375篇 |
自动化技术 | 25787篇 |
出版年
2023年 | 1514篇 |
2022年 | 2948篇 |
2021年 | 4275篇 |
2020年 | 3207篇 |
2019年 | 3258篇 |
2018年 | 4314篇 |
2017年 | 4552篇 |
2016年 | 4464篇 |
2015年 | 4392篇 |
2014年 | 6575篇 |
2013年 | 12904篇 |
2012年 | 9638篇 |
2011年 | 11547篇 |
2010年 | 9769篇 |
2009年 | 10421篇 |
2008年 | 10550篇 |
2007年 | 10520篇 |
2006年 | 10233篇 |
2005年 | 9376篇 |
2004年 | 7962篇 |
2003年 | 7546篇 |
2002年 | 7053篇 |
2001年 | 7287篇 |
2000年 | 7161篇 |
1999年 | 7956篇 |
1998年 | 17905篇 |
1997年 | 12144篇 |
1996年 | 9615篇 |
1995年 | 7186篇 |
1994年 | 6185篇 |
1993年 | 5865篇 |
1992年 | 4020篇 |
1991年 | 3770篇 |
1990年 | 3604篇 |
1989年 | 3374篇 |
1988年 | 3085篇 |
1987年 | 2393篇 |
1986年 | 2446篇 |
1985年 | 2697篇 |
1984年 | 2394篇 |
1983年 | 2116篇 |
1982年 | 1954篇 |
1981年 | 2090篇 |
1980年 | 1823篇 |
1979年 | 1683篇 |
1978年 | 1668篇 |
1977年 | 2052篇 |
1976年 | 2716篇 |
1975年 | 1432篇 |
1974年 | 1378篇 |
排序方式: 共有10000条查询结果,搜索用时 80 毫秒
101.
102.
Dr. Omer K. Rasheed Cassandra Buhl Dr. Jay T. Evans Dr. Kendal T. Ryter 《ChemMedChem》2021,16(8):1246-1251
Mincle agonists have been shown to induce inflammatory cytokine production, such as tumor necrosis factor-alpha (TNF) and promote the development of a Th1/Th17 immune response that might be crucial to development of effective vaccination against pathogens such as Mycobacterium tuberculosis. As an expansion of our previous work, a library of 6,6′-amide and sulfonamide α,α-d -trehalose compounds with various substituents on the aromatic ring was synthesized efficiently in good to excellent yields. These compounds were evaluated for their ability to activate the human C-type lectin receptor Mincle by the induction of cytokines from human peripheral blood mononuclear cells. A preliminary structure–activity relationship (SAR) of these novel trehalose diamides and sulfonamides revealed that aryl amide-linked trehalose compounds demonstrated improved activity and relatively high potency cytokine production compared to the Mincle ligand trehalose dibehenate adjuvant (TDB) and the natural ligand trehalose dimycolate (TDM) inducing dose-dependent and human-Mincle-specific stimulation in a HEK reporter cell line. 相似文献
103.
P. Carrasqueira H. Rocha J. M. Dias T. Ventura B. C. Ferreira M. C. Lopes 《International Transactions in Operational Research》2023,30(1):206-223
Radiation therapy is a technology-driven cancer treatment modality that has experienced significant advances over the last decades, due to multidisciplinary contributions that include engineering and computing. Recent technological developments allow the use of noncoplanar volumetric modulated arc therapy (VMAT), one of the most recent photon treatment techniques, in clinical practice. In this work, an automated noncoplanar arc trajectory optimization framework designed in two modular phases is presented. First, a noncoplanar beam angle optimization algorithm is used to obtain a set of noncoplanar irradiation directions. Then, anchored in these directions, an optimization strategy is proposed to compute an optimal arc trajectory. The computational experiments considered a pool of twelve difficult head-and-neck tumor cases. It was possible to observe that, for some of these cases, the optimized noncoplanar arc trajectories led to significant treatment planning quality improvements, when compared with coplanar VMAT treatment plans. Although these experiments were done in a research environment treatment planning software (matRad), the conclusions can be of interest for a clinical setting: automated procedures can simplify the current treatment workflow, produce high-quality treatment plans, making better use of human resources and allowing for unbiased comparisons between different treatment techniques. 相似文献
104.
Tolmachev A. M. Kuznetsova T. A. Fomenkov P. E. 《Protection of Metals and Physical Chemistry of Surfaces》2021,57(3):433-436
Protection of Metals and Physical Chemistry of Surfaces - The conditions for carrying out molecular dynamics calculations of adsorption isotherms of gases and vapors in micropores of active carbons... 相似文献
105.
106.
Kozhitov L. V. Kiselev B. G. Raykova T. B. Popkova A. V. Kostishin V. G. Muratov D. G. Yakushko E. V. Kosushkin V. G. Bebenin V. G. 《Russian Microelectronics》2019,48(8):599-612
Russian Microelectronics - The recently developed nanomaterials and their production technologies as intellectual property objects (IPOs) are considered. The role of the informational-analytical... 相似文献
107.
Wei-Li Xie Xiao-Dong Zhang Wen-Hui Liu Qi Xie Guang-Wu Wen Xiao-Xiao Huang Jian-Dong Zhu Fei-Xiang Ma 《稀有金属(英文版)》2019,(3)
SiC nano wires were fabricated on the silicon substrate dipped with a layer of Ni catalyst at 900 ℃ by gas pressure annealing processing. The morphologies and crystal structures were determined by scanning electron microscopy(SEM), transmission electron microscopy(TEM)and X-ray diffraction(XRD). The results show that the assynthesized nanowires are β-SiC single crystalline with diameter range of 50-100 nm, and length of tens of micron by directly annealing at 900 ℃. The SiC nano wires grow along the [111] direction with highly uniform morphology. And the possible growth mechanism of SiC nano wires is proposed.The present work provides an efficient strategy for the production of high-quality SiC nano wires. 相似文献
108.
Geetha R. Madhusudhan V. Padmavathy T. Lallithasree A. 《Wireless Personal Communications》2019,108(3):1957-1976
Wireless Personal Communications - The majority of security systems for wireless sensor networks are based on symmetric encryption. The main open issue for these approaches concerns the... 相似文献
109.
Wen Cao Zhonghua Zhou Chenyu Li Qun Wang Yue Huang Shirley Shen 《Ceramics International》2021,47(2):1807-1818
Sodalime float (SF) glass is widely used in our societies and industries. Hydrothermal corrosion method is one of the effective ways to prepare a superhydrophobic glass, but there is still lack of knowledge about hydrothermal corrosion behavior and mechanism of SF glass. We have hydrothermally treated SF glass at 180 °C for different time, and tried to reveal the aqueous corrosion process of SF glass. We have characterized the morphologies and chemical compositions of samples, and found that (1) the two sides of SF glass have different corrosion resistances, and (2) a multilayer structural coating with a nanoflake layer (Mg-rich gel layer), a nanowire layer (Ca-rich gel layer), and a porous layer (etched layer) is formed on the air-side of SF glass. Based on the experimental results, we have proposed an aqueous corrosion mechanism of SF glass. The insights of the hydrothermal corrosion behaviors and mechanism provide helpful guidelines to glass surface structural control and functionalization. 相似文献
110.
Qinhua Wang Xiaofeng Pan Xinpin Wang Shilin Cao Lihui Chen Xiaojuan Ma Liulian Huang Yonghao Ni 《Ceramics International》2021,47(4):4398-4403
Ti3C2Tx (MXene), a new kind of 2D ceramic nanosheets, is receiving more and more attention in the fields of medicine, biology, energy, electronics, etc. However, the preparation and application of MXene in hydrogel is still in its infancy period. Here, we review the latest progress (after 2018) related to MXene hydrogels in time. Aiming at the key issue of the dispersion stability of MXene in hydrogel systems, the preparation strategy, mechanism, advantages and disadvantages of MXene hydrogels are sorted out in detail, and the potential application prospects of MXene composite hydrogel are introduced. Finally, future viewpoints are put forward for the dispersion stability challenges that need solving in the design of MXene hydrogel. 相似文献