全文获取类型
收费全文 | 20910篇 |
免费 | 3763篇 |
国内免费 | 3323篇 |
专业分类
化学 | 16193篇 |
晶体学 | 297篇 |
力学 | 1269篇 |
综合类 | 259篇 |
数学 | 2269篇 |
物理学 | 7709篇 |
出版年
2024年 | 64篇 |
2023年 | 470篇 |
2022年 | 766篇 |
2021年 | 809篇 |
2020年 | 996篇 |
2019年 | 1015篇 |
2018年 | 823篇 |
2017年 | 837篇 |
2016年 | 1121篇 |
2015年 | 1159篇 |
2014年 | 1315篇 |
2013年 | 1659篇 |
2012年 | 1982篇 |
2011年 | 1998篇 |
2010年 | 1325篇 |
2009年 | 1439篇 |
2008年 | 1509篇 |
2007年 | 1256篇 |
2006年 | 1178篇 |
2005年 | 1011篇 |
2004年 | 754篇 |
2003年 | 635篇 |
2002年 | 632篇 |
2001年 | 534篇 |
2000年 | 395篇 |
1999年 | 389篇 |
1998年 | 256篇 |
1997年 | 232篇 |
1996年 | 212篇 |
1995年 | 210篇 |
1994年 | 170篇 |
1993年 | 164篇 |
1992年 | 121篇 |
1991年 | 102篇 |
1990年 | 87篇 |
1989年 | 57篇 |
1988年 | 52篇 |
1987年 | 48篇 |
1986年 | 48篇 |
1985年 | 34篇 |
1984年 | 21篇 |
1983年 | 27篇 |
1982年 | 10篇 |
1981年 | 12篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1975年 | 6篇 |
1965年 | 4篇 |
1959年 | 4篇 |
1957年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Nanomaterials with localized surface plasmon resonance (LSPR) locating in the near-infrared region have broad application prospects in the field of biomedicine. However, the biggest problem that limits the biomedical application of such nanomaterials lies in two aspects: First, the potential long-term in vivo toxicity caused by the metabolism of many nanomaterials with LSPR effect; Second, most of current nanomaterials with LSPR effect are difficult to achieve LSPR wavelength tunability in the near-infrared region to adapt to different biomedical applications. Copper selenide nanomaterials are composed of selenium and copper, which are necessary nutrient elements for human life. Because of the active and flexible chemical properties of selenium and copper, copper selenide nanomaterials can not only be effectively degraded and utilized in human body, but also be endowed with various physicochemical properties by chemical modification or doping. Recently, copper selenide nanomaterials have shown unique properties such as LSPR in the near-infrared region, making them attractive for near-infrared thermal ablation, photoacoustic imaging, disease marker detection, multimode imaging, and so on. Currently, to the best of our knowledge, there is no review on the LSPR properties of copper selenide nanomaterials and its biomedical applications. This review first discusses the relationship between the physicochemical properties and the LSPR of copper selenide nanomaterials and then summarizes the latest progress in the application of copper selenide nanomaterials in biological detection, diagnosis, and treatment of diseases. In addition, the advantages, and prospects of copper selenide nanomaterials in biomedicine are also highlighted. 相似文献
992.
Yueteng Zhang Peng Ji Xiang Meng Feng Gao Fanxun Zeng Wei Wang 《Molecules (Basel, Switzerland)》2021,26(12)
A simple arylamine-catalyzed Mannich-cyclization cascade reaction was developed for facile synthesis of substituted 2H-benzo[h]chromenes. The notable feature of the process included the efficient generation of ortho-quinone methides (o-QMs) catalyzed by a simple aniline. The mild reaction conditions allowed for a broad spectrum of 1- and 2-naphthols and trans-cinnamaldehydes to engage in the cascade sequence with high efficiency. 相似文献
993.
994.
Zhan-Dong Yang Yi-Shan Guo Jun-Sheng Huang Ya-Fei Gao Fei Peng Ri-Yi Xu Hui-Hui Su Ping-Jun Zhang 《Molecules (Basel, Switzerland)》2021,26(9)
In vitro experiments have indicated prebiotic activity of isomaltulose, which stimulates the growth of probiotics and the production of short chain fatty acids (SCFAs). However, the absence of in vivo trials undermines these results. This study aims to investigate the effect of isomaltulose on composition and functionality of gut microbiota in rats. Twelve Sprague–Dawley rats were divided into two groups: the IsoMTL group was given free access to water containing 10% isomaltulose (w/w), and the control group was treated with normal water for five weeks. Moreover, 16S rRNA sequencing showed that ingestion of isomaltulose increased the abundances of beneficial microbiota, such as Faecalibacterium and Phascolarctobacterium, and decreased levels of pathogens, including Shuttleworthia. Bacterial functional prediction showed that isomaltulose affected gut microbial functionalities, including secondary bile acid biosynthesis. Targeted metabolomics demonstrated that isomaltulose supplementation enhanced cholic acid concentration, and reduced levels of lithocholic acid, deoxycholic acid, dehydrocholic acid, and hyodeoxycholic acid. Moreover, the concentrations of propionate and butyrate were elevated in the rats administered with isomaltulose. This work suggests that isomaltulose modulates gut microbiota and the production of SCFAs and secondary bile acids in rats, which provides a scientific basis on the use of isomaltulose as a prebiotic. 相似文献
995.
Yifen HU Pengyu GAO Zhen XU Chuan ZHANG Lizhen HUANG Yunting HU Yarui AN Yingying GU 《Turkish Journal of Chemistry》2021,45(1):248
Ni(II)/CSs were prepared using a simple two-step hydrothermal method. The morphology and composition of the catalysts were studied with scanning electron microscope, transmission electron microscope, and X-ray diffraction. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy showed that the surface of the prepared carbon spheres was rich in hydroxyl groups, which was beneficial to remove CO intermediates, and therefore, improving the catalytic efficiency and the antipoisoning ability of the catalysts. The results of cyclic voltammetry and chronoamperometry showed that the electrocatalytic activity and stability of Ni(II)/CSs were higher than that of unloaded NiAc under alkaline environment. When the nickel content was 5 wt.%, the peak oxidation current density of methanol on Ni(II)/CSs electrocatalyst reached the maximum of 34.54 mA/cm2, which was about 1.8 times that of unloaded NiAc. These results indicate that Ni(II)/CSs has potential applications in the electrocatalytic oxidation of methanol. 相似文献
996.
Cai Mengmeng Yao Lijuan Zhu Man Tao Peng Nan Ruihua Jian Zengyun 《Journal of Thermal Analysis and Calorimetry》2021,143(4):2911-2918
Journal of Thermal Analysis and Calorimetry - Differential scanning calorimetry was used to investigate the non-isothermal crystallization kinetics of the Fe76.5Nb3B20Cu0.5 glassy alloys. The... 相似文献
997.
Liu Shengjie Zhou Shengbo Peng Aihong 《Journal of Thermal Analysis and Calorimetry》2021,144(3):657-669
Journal of Thermal Analysis and Calorimetry - Applying foamed warm-mix asphalt in pavement has attracted great attention, but its effects on asphalt mastic are not clear. This research investigated... 相似文献
998.
Peng Liu Hui Ruan Tiantian Li Jiaqi Chen Fuqiu Ma Duoqiang Pan Wangsuo Wu 《Molecules (Basel, Switzerland)》2021,26(4)
The low cost β-zeolite and ethylenediamine modified β-zeolite (EDA@β-zeolite) were prepared by self-assembly method and used for Cu(II) removal from contaminated aqueous solution. Removal ability of β-zeolite toward Cu(II) was greatly improved after ethylenediamine (EDA) modification, the removal performance was greatly affected by environmental conditions. XPS results illustrated that the amide group played important role in the removal process by forming complexes with Cu(II). The EDA@β-zeolite showed desirable recycling ability. The finding herein suggested that the proposed composite is a promising and suitable candidate for the removal of Cu(II) from contaminated natural wastewater and aquifer. 相似文献
999.
水资源匮乏是现代化发展中面临的全球性问题,太阳能界面水汽转换(Interfacial Solar Steam Generation, ISSG)是一种高效、绿色、低成本进行海水淡化和废水处理的方法。ISSG使用绿色的太阳能作为热源,通过光热转换并将热限制在水气界面上以高效产生蒸气,然后经过冷凝收集获得清洁水。设计和构筑具有强光吸收的光热转换材料是ISSG的技术核心。Ti3C2-MXene是一种新型二维碳化钛材料,具有比表面积大、水分散性好和光热转换效率高等优点,在ISSG领域具有巨大的应用潜力。本文介绍了ISSG技术和MXene,总结了光热转换材料的设计原则,论述了Ti3C2-MXene复合材料在ISSG领域的研究进展,其中包括二维MXene薄膜、三维MXene气凝胶和水凝胶、生物基-MXene复合材料的构筑和性能等,并分析了Ti3C2-MXene所面临的挑战和发展前景。 相似文献
1000.
The research of photo-responsive materials, with changed absorption and emission under light stimulus, has drawn more and more attention due to their wide applications. However, most of them suffered from the notorious aggregation-caused quenching(ACQ) effect, which often led to the unconspicuous luminescent change in photo-responsive process. To solve this problem, the strategy of combining aggregation-induced emission(AIE) and photochromic properties was utilized, which largely enriched the phenomenon and application of photo-responsive materials. This short review summarized the recent progress of photo-responsive AIE materials with changed UV absorbance or PL phenomenon under UV-irradiation, including the types of molecular structures, internal mechanisms and the practical applications. Also, some outlooks were given on the further exploration of this field at the end of this paper. 相似文献