全文获取类型
收费全文 | 69930篇 |
免费 | 5232篇 |
国内免费 | 2784篇 |
专业分类
电工技术 | 3442篇 |
技术理论 | 10篇 |
综合类 | 4071篇 |
化学工业 | 12219篇 |
金属工艺 | 3778篇 |
机械仪表 | 4315篇 |
建筑科学 | 5946篇 |
矿业工程 | 2003篇 |
能源动力 | 2059篇 |
轻工业 | 4231篇 |
水利工程 | 1104篇 |
石油天然气 | 4365篇 |
武器工业 | 534篇 |
无线电 | 8216篇 |
一般工业技术 | 8937篇 |
冶金工业 | 3586篇 |
原子能技术 | 784篇 |
自动化技术 | 8346篇 |
出版年
2024年 | 250篇 |
2023年 | 1122篇 |
2022年 | 1851篇 |
2021年 | 2523篇 |
2020年 | 1997篇 |
2019年 | 1761篇 |
2018年 | 1920篇 |
2017年 | 2215篇 |
2016年 | 1997篇 |
2015年 | 2631篇 |
2014年 | 3252篇 |
2013年 | 3895篇 |
2012年 | 4278篇 |
2011年 | 4517篇 |
2010年 | 3933篇 |
2009年 | 3722篇 |
2008年 | 3652篇 |
2007年 | 3647篇 |
2006年 | 3843篇 |
2005年 | 3326篇 |
2004年 | 2292篇 |
2003年 | 2001篇 |
2002年 | 1929篇 |
2001年 | 1752篇 |
2000年 | 1755篇 |
1999年 | 2026篇 |
1998年 | 1811篇 |
1997年 | 1487篇 |
1996年 | 1419篇 |
1995年 | 1082篇 |
1994年 | 1035篇 |
1993年 | 714篇 |
1992年 | 549篇 |
1991年 | 440篇 |
1990年 | 329篇 |
1989年 | 262篇 |
1988年 | 238篇 |
1987年 | 149篇 |
1986年 | 105篇 |
1985年 | 80篇 |
1984年 | 38篇 |
1983年 | 36篇 |
1982年 | 40篇 |
1981年 | 22篇 |
1980年 | 14篇 |
1979年 | 5篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
991.
992.
Bingmei Sun Jinrui Wu Shaobin Cui Huanhuan Zhu Wei An Qingge Fu Chengwei Shao Aihua Yao Bingdi Chen Donglu Shi 《Nano Research》2017,10(1):37-48
Graphene oxide/gold nanorod (GO/GNR) nanohybrids were synthesized with a GO- and gold-seed-mediated in situ growth method at room temperature by mixing polystyrene sulfonate (PSS) functionalized GO, secondary growth solution, and gold seeds. Compared with ex situ preparation methods of GO/GNRs or graphene (G)/GNRs, the in situ synthesis of GO/GNRs addressed the issue of the aggregation of the GNRs before their attachment onto the GO. The method is straightforward and environment-friendly. The GO/GNRs showed a remarkable photothermal effect in vitro. The temperature of the GO/GNR nanohybrids increased from 25 to 49.9 °C at a concentration of 50 μg/mL after irradiation with an 808-nm laser (0.4 W/cm2) for 6 min. Additionally, the GO/GNRs exhibited good optical and morphological stability and photothermal properties after six cycles of laser irradiation. Upon injection of the GO/GNRs into xenograft tumors, excellent computed tomography (CT) imaging properties and photothermal effect were obtained. The preclinical CT agent iohexol was combined with the GO/GNRs and further enhanced CT imaging. Therefore, the GO/GNR nanohybrids have great potential for precise CT-image-guided tumor photothermal treatment. 相似文献
993.
The characteristics of a double teeth-shaped plasmonic optical switch are analyzed. Based on the metal–insulator–metal waveguide consisting of double rectangular teeth, a nanoscale liquid crystal optical switch is proposed and numerically simulated by using the finite difference time domain method with a perfectly matched layer absorbing boundary condition. It is found that the double teeth-shaped structure filled with liquid crystal can realize the function of a switch. The modulation depth of the double teeth-shaped structure is larger than 50?dB. 相似文献
994.
995.
996.
Jinkai Wang Lei Zhu Fang Li Tianhao Yao Ting Liu Yonghong Cheng Zongyou Yin Hongkang Wang 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(33)
Sodium‐ion batteries (SIBs) have been recognized as the promising alternatives to lithium‐ion batteries for large‐scale applications owing to their abundant sodium resource. Currently, one significant challenge for SIBs is to explore feasible anodes with high specific capacity and reversible pulverization‐free Na+ insertion/extraction. Herein, a facile co‐engineering on polymorph phases and cavity structures is developed based on CoMo‐glycerate by scalable solvothermal sulfidation. The optimized strategy enables the construction of CoMoOxSy with synergized partially sulfidized amorphous phase and yolk–shell confined cavity. When developed as anodes for SIBs, such CoMoOxSy electrodes deliver a high reversible capacity of 479.4 mA h g?1 at 200 mA g?1 after 100 cycles and a high rate capacity of 435.2 mA h g?1 even at 2000 mA g?1, demonstrating superior capacity and rate capability. These are attributed to the unique dual merits of the anodes, that is, the elastic bountiful reaction pathways favored by the sulfidation‐induced amorphous phase and the sodiation/desodiation accommodatable space benefits from the yolk–shell cavity. Such yolk–shell nano‐battery materials are merited with co‐tunable phases and structures, facile scalable fabrication, and excellent capacity and rate capability in sodium storage. This provides an opportunity to develop advanced practical electrochemical sodium storage in the future. 相似文献
997.
Selective laser melting technology is used to manufacture porous and solid AZ91D alloys. The effects of laser power and hatch spacing on the density, blowholes, microstructure and mechanical properties of AZ91D alloy are studied. The laser power and hatch spacing play a significant role in the density and blowholes of AZ91D specimens. The grains size of specimens increases from 1 μm–2 μm to 8 μm–10 μm from the bottom to the top in single molten pool. Compared with grain size of die‐casting alloy (30 μm), that of selective laser melted gets refinement. There is no significant change in microstructure in the bottom, middle and top of specimens. The micro‐hardness of AZ91D alloy, reaching up to 115.3 HV 0.1, is superior to that of die‐casting alloy (56 HV 0.1). The compression properties of porous and solid specimens reach the degree of die‐casting solid magnesium alloy. AZ91D alloy shows the potential in the application of medical biodegradable materials. 相似文献
998.
999.
Chemistry gives us the ability to manipulate atoms and molecules into nanometer and micrometer scale building blocks, while
the science of crystallography is concerned with the spatial arrangement of atoms, ions, and molecules and thus the morphology
and structures of materials. Complex three-dimensional ZnS nanostructures have been fabricated via step-by-step crystallographically-controlled
chemical processes. Tricrystals of ZnS whiskers were prepared via a controlled thermal evaporation process, and then the tricrystals
were thermally treated in an atmosphere formed by evaporating B-N-O precursors into N2/NH3 to afford BN-coated arrays of nanobranches. The ZnS nanobranches grew epitaxially on the ternary facets and extended in three
[0001] directions forming ordered nanostructures. Meanwhile, the protecting insulating sheath of BN formed on the ZnS nanostructures
confined the growth of the nanospines and enhanced their stability. The method may be extended to fabricate other semiconductor
nanomaterials with novel structures.
相似文献
1000.
Yongfeng Zhou Wei Huang Jinyao Liu Xinyuan Zhu Deyue Yan 《Advanced materials (Deerfield Beach, Fla.)》2010,22(41):4567-4590
Hyperbranched polymers (HBPs) are highly branched macromolecules with a three‐dimensional dendritic architecture. Due to their unique topological structure and interesting physical/chemical properties, HBPs have attracted wide attention from both academia and industry. In this paper, the recent developments in HBP self‐assembly and their biomedical applications have been comprehensively reviewed. Many delicate supramolecular structures from zero‐dimension (0D) to three‐dimension (3D), such as micelles, fibers, tubes, vesicles, membranes, large compound vesicles and physical gels, have been prepared through the solution or interfacial self‐assembly of amphiphilic HBPs. In addition, these supramolecular structures have shown promising applications in the biomedical areas including drug delivery, protein purification/detection/delivery, gene transfection, antibacterial/antifouling materials and cytomimetic chemistry. Such developments promote the interdiscipline researches among surpramolecular chemistry, biomedical chemistry, nanotechnology and functional materials. 相似文献