全文获取类型
收费全文 | 48927篇 |
免费 | 5926篇 |
国内免费 | 2497篇 |
专业分类
电工技术 | 2555篇 |
技术理论 | 8篇 |
综合类 | 3198篇 |
化学工业 | 16178篇 |
金属工艺 | 3037篇 |
机械仪表 | 1674篇 |
建筑科学 | 3101篇 |
矿业工程 | 1209篇 |
能源动力 | 2980篇 |
轻工业 | 2579篇 |
水利工程 | 845篇 |
石油天然气 | 2727篇 |
武器工业 | 231篇 |
无线电 | 2461篇 |
一般工业技术 | 8748篇 |
冶金工业 | 3377篇 |
原子能技术 | 432篇 |
自动化技术 | 2010篇 |
出版年
2024年 | 271篇 |
2023年 | 1109篇 |
2022年 | 1625篇 |
2021年 | 1743篇 |
2020年 | 1872篇 |
2019年 | 1697篇 |
2018年 | 1587篇 |
2017年 | 1830篇 |
2016年 | 2004篇 |
2015年 | 1874篇 |
2014年 | 2899篇 |
2013年 | 2995篇 |
2012年 | 3628篇 |
2011年 | 4000篇 |
2010年 | 2882篇 |
2009年 | 2971篇 |
2008年 | 2414篇 |
2007年 | 2978篇 |
2006年 | 2856篇 |
2005年 | 2422篇 |
2004年 | 2033篇 |
2003年 | 1815篇 |
2002年 | 1477篇 |
2001年 | 1159篇 |
2000年 | 998篇 |
1999年 | 785篇 |
1998年 | 651篇 |
1997年 | 472篇 |
1996年 | 433篇 |
1995年 | 355篇 |
1994年 | 325篇 |
1993年 | 223篇 |
1992年 | 188篇 |
1991年 | 144篇 |
1990年 | 136篇 |
1989年 | 83篇 |
1988年 | 64篇 |
1987年 | 57篇 |
1986年 | 40篇 |
1985年 | 62篇 |
1984年 | 52篇 |
1983年 | 46篇 |
1982年 | 31篇 |
1981年 | 8篇 |
1980年 | 15篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1963年 | 2篇 |
1959年 | 5篇 |
1951年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
Carbon Nanotubes: Carbon Nanotubes Disrupt Iron Homeostasis and Induce Anemia of Inflammation through Inflammatory Pathway as a Secondary Effect Distant to Their Portal‐of‐Entry (Small 15/2017)
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
982.
Carbon Nanodot‐Sensitized Modulation of Alzheimer's β‐Amyloid Self‐Assembly,Disassembly, and Toxicity
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
You Jung Chung Kayoung Kim Byung Il Lee Chan Beum Park 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(34)
The self‐assembly of amyloidogenic peptides into β‐sheet‐rich aggregates is a general feature of many neurodegenerative diseases, including Alzheimer's disease, which signifies the need for the effective attenuation of amyloid aggregation toward alleviating amyloid‐associated neurotoxicity. This study reports that photoluminescent carbon nanodots (CDs) can effectively suppress Alzheimer's β‐amyloid (Aβ) self‐assembly and function as a β‐sheet breaker disintegrating preformed Aβ aggregates. This study synthesizes CDs using ammonium citrate through one‐pot hydrothermal treatment and passivates their surface with branched polyethylenimine (bPEI). The bPEI‐coated CDs (bPEI@CDs) exhibit hydrophilic and cationic surface characteristics, which interact with the negatively charged residues of Aβ peptides, suppressing the aggregation of Aβ peptides. Under light illumination, bPEI@CDs display a more pronounced effect on Aβ aggregation and on the dissociation of β‐sheet‐rich assemblies through the generation of reactive oxygen species from photoactivated bPEI@CDs. The light‐triggered attenuation effect of Aβ aggregation using a series of experiments, including photochemical and microscopic analysis, is verified. Furthermore, the cell viability test confirms the ability of photoactivated bPEI@CDs for the suppression of Aβ‐mediated cytotoxicity, indicating bPEI@CDs' potency as an effective anti‐Aβ neurotoxin agent. 相似文献
983.
Fabrication of Fe3O4 Dots Embedded in 3D Honeycomb‐Like Carbon Based on Metallo–Organic Molecule with Superior Lithium Storage Performance
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Chengfei Li Liuqing Li Zhaopeng Li Weihao Zhong Zhenghui Li Xiaoqing Yang Guoqing Zhang Haiyan Zhang 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(38)
A novel metallo–organic molecule, ferrocene, is selected as building block to construct Fe3O4 dots embedded in 3D honeycomb‐like carbon (Fe3O4 dots/3DHC) by using SiO2 nanospheres as template. Unlike previously used inorganic Fe3O4 sources, ferrocene simultaneously contains organic cyclopentadienyl groups and inorganic Fe atoms, which can be converted to carbon and Fe3O4, respectively. Atomic‐scale Fe distribution in started building block leads to the formation of ultrasmall Fe3O4 dots (≈3 nm). In addition, by well controlling the feed amount of ferrocene, Fe3O4 dots/3DHC with well‐defined honeycomb‐like meso/macropore structure and ultrathin carbon wall can be obtained. Owing to unique structural features, Fe3O4 dots/3DHC presents impressive lithium storage performance. The initial discharge and reversible capacities can reach 2047 and 1280 mAh g?1 at 0.05 A g?1. With increasing the current density to 1 and 3 A g?1, remarkable capacities of 963 and 731 mAh g?1 remain. Moreover, Fe3O4 dots/3DHC also has superior cycling stability, after a long‐term charge/discharge for 200 times, a high capacity of 1082 mAh g?1 can be maintained (80% against the capacity of the 2nd cycle). 相似文献
984.
Self‐Powered,Flexible, and Solution‐Processable Perovskite Photodetector Based on Low‐Cost Carbon Cloth
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Haoxuan Sun Tianyu Lei Wei Tian Fengren Cao Jie Xiong Liang Li 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(28)
Flexible perovskite photodetectors are usually constructed on indium‐tin‐oxide‐coated polymer substrates, which are expensive, fragile, and not resistant to high temperature. Herein, for the first time, a high‐performance flexible perovskite photodetector is fabricated based on low‐cost carbon cloth via a facile solution processable strategy. In this device, perovskite microcrystal and Spiro‐OMeTAD (hole transporting material) blended film act as active materials for light detection, and carbon cloth serves as both a flexible substrate and a conductive electrode. The as‐fabricated photodetector shows a broad spectrum response from ultraviolet to near‐infrared light, high responsivity, fast response speed, long‐term stability, and self‐powered capability. Flexible devices show negligible degradation after several tens of bending cycles and at the extremely bending angle of 180°. This work promises a new technique to construct flexible, high‐performance photodetectors with low cost and self‐powered capability. 相似文献
985.
Carbon nanosheets with a tunable mesopore size,large pore volume,and good electronic conductivity are synthesized via a solution-chemistry approach.In this synthesis,diaminohexane and graphene oxide (GO) are used as the structural directing agents,and a silica colloid is used as a mesopores template.Diaminohexane plays a crucial role in bridging silica colloid particles and GO,as well as initiating the polymerization of benzoxazine on the surfaces of both the GO and silica,resulting in the formation of a hybrid nanosheet polymer.The carbon nanosheets have graphene embedded in them and have several spherical mesopores with a pore volume up to 3.5 cm3·g-1 on their surfaces.These nuerous accessible mesopores in the carbon layers can act as reservoirs to host a high loading of active charge-storage materials with good dispersion and a uniform particle size.Compared with active materials with wide particle-size distributions,the unique proposed configuration with confined and uniform particles exhibits superior electrochemical performance during lithiation and delithiation,especially during long cycles and at high rates. 相似文献
986.
Under water-rich conditions, small amphiphilic and hydrophobic drug molecules self-assemble into supramolecular nanostructures. Thus, substantial modifications in their interaction with cellular structures and the ability to reach intracellular targets could happen. Additionally, drug aggregates could be more toxic than the non-aggregated counterparts, or vice versa. Moreover, since self-aggregation reduces the number of effective “monomeric” molecules that interact with the target, the drug potency could be underestimated. In other cases, the activity could be ascribed to the non-aggregated molecule while it stems from its aggregates. Thus, drug self-assembly could mislead from drug throughput screening assays to advanced preclinical and clinical trials. Finally, aggregates could serve as crystallization nuclei. The impact that this phenomenon has on the biological performance of active compounds, the inconsistent and often controversial nature of the published data and the need for recommendations/guidelines as preamble of more harmonized research protocols to characterize drug self-aggregation were main motivations for this review. First, the key molecular and environmental parameters governing drug self-aggregation, the main drug families for which this phenomenon and the methods used for its characterization are described. Then, promising nanotechnology platforms investigated to prevent/control it towards a more efficient drug development process are briefly discussed. 相似文献
987.
Tran Huu Nam Ken Goto Kahori Oshima E.V.A. Premalal Yoshinobu Shimamura Yoku Inoue 《Advanced Composite Materials》2016,25(1):73-86
A solid-state drawing and winding process was done to create thin aligned carbon nanotube (CNT) sheets from CNT arrays. However, waviness and poor packing of CNTs in the sheets are two main weaknesses restricting their reinforcing efficiency in composites. This report proposes a simple press-drawing technique to reduce wavy CNTs and to enhance dense packing of CNTs in the sheets. Non-pressed and pressed CNT/epoxy composites were developed using prepreg processing with a vacuum-assisted system. Effects of pressing on the mechanical properties of the aligned CNT sheets and CNT/epoxy composites were examined. Pressing with distributed loads of 147, 221, and 294 N/m showed a substantial increase in the tensile strength and the elastic modulus of the aligned CNT sheets and their composites. The CNT sheets under a press load of 221 N/m exhibited the best mechanical properties found in this study. With a press load of 221 N/m, the pressed CNT sheet and its composite, respectively, enhanced the tensile strength by 139.1 and 141.9%, and the elastic modulus by 489 and 77.6% when compared with non-pressed ones. The pressed CNT/epoxy composites achieved high tensile strength (526.2 MPa) and elastic modulus (100.2 GPa). Results show that press-drawing is an important step to produce superior CNT sheets for development of high-performance CNT composites. 相似文献
988.
Huijun Yu Run Shi Yufei Zhao Geoffrey I. N. Waterhouse Li‐Zhu Wu Chen‐Ho Tung Tierui Zhang 《Advanced materials (Deerfield Beach, Fla.)》2016,28(43):9454-9477
Efficient capture of solar energy will be critical to meeting the energy needs of the future. Semiconductor photocatalysis is expected to make an important contribution in this regard, delivering both energy carriers (especially H2) and valuable chemical feedstocks under direct sunlight. Over the past few years, carbon dots (CDs) have emerged as a promising new class of metal‐free photocatalyst, displaying semiconductor‐like photoelectric properties and showing excellent performance in a wide variety of photoelectrochemical and photocatalytic applications owing to their ease of synthesis, unique structure, adjustable composition, ease of surface functionalization, outstanding electron‐transfer efficiency and tunable light‐harvesting range (from deep UV to the near‐infrared). Here, recent advances in the rational design of CDs‐based photocatalysts are highlighted and their applications in photocatalytic environmental remediation, water splitting into hydrogen, CO2 reduction, and organic synthesis are discussed. 相似文献
989.
990.