全文获取类型
收费全文 | 3141篇 |
免费 | 762篇 |
国内免费 | 103篇 |
专业分类
化学 | 3041篇 |
晶体学 | 45篇 |
力学 | 3篇 |
综合类 | 2篇 |
数学 | 2篇 |
物理学 | 443篇 |
无线电 | 470篇 |
出版年
2024年 | 4篇 |
2023年 | 33篇 |
2022年 | 19篇 |
2021年 | 83篇 |
2020年 | 162篇 |
2019年 | 137篇 |
2018年 | 92篇 |
2017年 | 96篇 |
2016年 | 211篇 |
2015年 | 235篇 |
2014年 | 257篇 |
2013年 | 296篇 |
2012年 | 283篇 |
2011年 | 252篇 |
2010年 | 293篇 |
2009年 | 277篇 |
2008年 | 289篇 |
2007年 | 227篇 |
2006年 | 218篇 |
2005年 | 169篇 |
2004年 | 160篇 |
2003年 | 123篇 |
2002年 | 20篇 |
2001年 | 22篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 20篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1990年 | 2篇 |
1985年 | 1篇 |
排序方式: 共有4006条查询结果,搜索用时 15 毫秒
161.
Tianyu Yuan Shijie Xiong Xinghai Shen 《Angewandte Chemie (International ed. in English)》2020,59(40):17719-17725
The coordination of actinides and lanthanides, as well as strontium and cesium with graphdiyne (GDY) was studied experimentally and theoretically. On the basis of experimental results and/or theoretical calculations, it was suggested that Th4+, Pu4+, Am3+, Cm3+, and Cs+ exist in single‐ion states on the special triangular structure of GDY with various coordination patterns, wherein GDY itself is deformed in different ways. Both experiment and theoretical calculations strongly indicate that UO22+, La3+, Eu3+, Tm3+ and Sr2+ are not adsorbed by GDY at all. The distinguished adsorption behaviors of GDY afford an important strategy for highly selective separation of actinides and lanthanides, Th4+ and UO22+, and Cs+ and Sr2+, in the nuclear fuel cycle. Also, the present work sheds light on an approach to explore the unique functions and physicochemical properties of actinides in single‐ion states. 相似文献
162.
不含金属的碳材料通过廉价且易获得的柚子皮经KOH活化和高温热解获得,该碳材料具有高比表面积(1 055 m~2·g~(-1))和高石墨化程度的类蜂窝状结构。将多孔碳(PAC)材料修饰后的电极作为工作电极,采用阳极溶出伏安法(SWASV)同步检测Cd~(2+)、Pb~(2+)和Cu~(2+)离子,表现出较高的灵敏度、可重复性、稳定性和较低的检测限。研究认为PAC的微孔和中孔可以充当有效的离子传递通道,从而加速离子的扩散并显著提高交换效率,而高的石墨化程度提高了材料的导电性,加速了电子传输。 相似文献
163.
Supramolecular Phthalocyanine Assemblies for Improved Photoacoustic Imaging and Photothermal Therapy
Xingshu Li Eun‐Yeong Park Youngnam Kang Nahyun Kwon Mengyao Yang Seunghyun Lee Won Jong Kim Chulhong Kim Juyoung Yoon 《Angewandte Chemie (International ed. in English)》2020,59(22):8630-8634
Phototheranostic nanoplatforms are of particular interest for cancer diagnosis and imaging‐guided therapy. Herein, we develop a supramolecular approach to fabricate a nanostructured phototheranostic agent through the direct self‐assembly of two water‐soluble phthalocyanine derivatives, PcS4 and PcN4. The nature of the molecular recognition between PcS4 and PcN4 facilitates the formation of nanostructure (PcS4‐PcN4) and consequently enables the fabrication of PcS4‐PcN4 with completely quenched fluorescence and reduced singlet oxygen generation, leading to the high photoacoustic and photothermal activity of PcS4‐PcN4. In vivo evaluations suggest that PcS4‐PcN4 could not only efficiently visualize a tumor with high contrast through whole‐body photoacoustic imaging but also enable excellent photothermal therapy for cancer. 相似文献
164.
采用脱合金化结合胶体聚沉的方法制备了纳米多孔Ni/RuO_2、Ni-Mo/RuO_2复合电极材料。通过X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电镜(SEM)、透射电镜(TEM)对电极材料的物相、元素组态、形貌结构、孔径大小和结晶度进行表征,并通过线性扫描伏安、交流阻抗以及循环伏安等方法测试多孔电极的电催化析氢性能。分析结果显示:RuO_2由于聚沉作用包覆在Ni基合金的骨架表面。Mo的加入使Ni-Mo合金非晶化的同时,促使其骨架细化,形成双连续的纳米多孔结构。Mo与RuO_2的加入以及Mo含量的增加均提高了电催化析氢性能。纳米多孔Ni_(2.5)Mo_(2.5)/RuO_2复合电极在50 mA·cm~(-2)的电流密度下析氢过电位为182 mV。 相似文献
165.
Prof. Meng Su Feifei Qin Zeying Zhang Bingda Chen Qi Pan Dr. Zhandong Huang Zheren Cai Zhipeng Zhao Prof. Xiaotian Hu Prof. Dominique Derome Prof. Jan Carmeliet Prof. Yanlin Song 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(34):14340-14346
A key issue of micro/nano devices is how to integrate micro/nanostructures with specified chemical components onto various curved surfaces. Hydrodynamic printing of micro/nanostructures on three-dimensional curved surfaces is achieved with a strategy that combines template-induced hydrodynamic printing and self-assembly of nanoparticles (NPs). Non-lithography flexible wall-shaped templates are replicated with microscale features by dicing a trench-shaped silicon wafer. Arising from the capillary pumped function between the template and curved substrates, NPs in the colloidal suspension self-assemble into close-packed micro/nanostructures without a gravity effect. Theoretical analysis with the lattice Boltzmann model reveals the fundamental principles of the hydrodynamic assembly process. Spiral linear structures achieved by two kinds of fluorescent NPs show non-interfering photoluminescence properties, while the waveguide and photoluminescence are confirmed in 3D curved space. The printed multiconstituent micro/nanostructures with single-NP resolution may serve as a general platform for optoelectronics beyond flat surfaces. 相似文献
166.
纳米材料具有荷载效率高、靶向性能好、半衰期较长等优点, 非常适于作为药物转运载体, 可有效提高药物的水溶性、稳定性和疾病治疗效果.目前, 开发具有良好生物相容性、可控靶向释放能力和精确载药位点的理想药物转运载体, 仍是该领域存在的挑战性问题和当前研究的重点.自组装DNA纳米结构是一类具有精确结构、功能多样的纳米生物材料, 具有良好的生物相容性和稳定性、较高的膜渗透性和可控靶向释放能力等优点, 是理想的药物转运载体和智能载药材料.本文总结了DNA纳米结构的发展历程、DNA纳米结构作为药物转运载体的研究现状、动态DNA纳米结构在智能载药中的应用进展, 并对其发展前景进行了展望. 相似文献
167.
Efficacious Anticancer Drug Delivery Mediated by a pH‐Sensitive Self‐Assembly of a Conserved Tripeptide Derived from Tyrosine Kinase NGF Receptor 下载免费PDF全文
Parikshit Moitra Krishan Kumar Prof. Paturu Kondaiah Prof. Santanu Bhattacharya 《Angewandte Chemie (International ed. in English)》2014,53(4):1113-1117
We present herein a short tripeptide sequence (Lys–Phe–Gly or KFG) that is situated in the juxtamembrane region of the tyrosine kinase nerve growth factor (Trk NGF) receptors. KFG self‐assembles in water and shows a reversible and concentration‐dependent switching of nanostructures from nanospheres (vesicles) to nanotubes, as evidenced by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. The morphology change was associated with a transition in the secondary structure. The tripeptide vesicles have inner aqueous compartments and are stable at pH 7.4 but rupture rapidly at pH≈6. The pH‐sensitive response of the vesicles was exploited for the delivery of a chemotherapeutic anticancer drug, doxorubicin, which resulted in enhanced cytotoxicity for both drug‐sensitive and drug‐resistant cells. Efficient intracellular release of the drug was confirmed by fluorescence‐activated cell sorting analysis, fluorescence microscopy, and confocal microscopy. 相似文献
168.
Dr. Guanjun Xiao Dr. Chunye Zhu Prof. Yanming Ma Prof. Bingbing Liu Prof. Guangtian Zou Prof. Bo Zou 《Angewandte Chemie (International ed. in English)》2014,53(3):729-733
There is an urgent need for the development in the field of the magnetism of topological insulators, owing to the necessity for the realization of the quantum anomalous Hall effect. Herein, we discuss experimentally fabricated nanostructured hierarchical architectures of the topological insulator Bi2Te3 without the introduction of any exotic magnetic dopants, in which intriguing room‐temperature ferromagnetism was identified. First‐principles calculations demonstrated that the intrinsic point defect with respect to the antisite Te site is responsible for the creation of a magnetic moment. Such a mechanism, which is different from that of a vacancy defect, provides new insights into the origins of magnetism. Our findings may pave the way for developing future Bi2Te3‐based dissipationless spintronics and fault‐tolerant quantum computation. 相似文献
169.
Fe K‐Edge X‐ray Absorption Fine Structure Determination of γ‐Al2O3‐Supported Iron‐Oxide Species 下载免费PDF全文
Dr. Atsuko Tomita Dr. Takeshi Miki Takeru Tango Tatsuro Murakami Hideyuki Nakagawa Dr. Yutaka Tai 《Chemphyschem》2015,16(9):2015-2020
The structure of FeOx species supported on γ‐Al2O3 was investigated by using Fe K‐edge X‐ray absorption fine structure (XAFS) and X‐ray diffraction (XRD) measurements. The samples were prepared through the impregnation of iron nitrate on Al2O3 and co‐gelation of aluminum and iron sulfates. The dependence of the XRD patterns on Fe loading revealed the formation of α‐Fe2O3 particles at an Fe loading of above 10 wt %, whereas the formation of iron‐oxide crystals was not observed at Fe loadings of less than 9.0 wt %. The Fe K‐edge XAFS was characterized by a clear pre‐edge peak, which indicated that the Fe?O coordination structure deviates from central symmetry and that the degree of Fe?O?Fe bond formation is significantly lower than that in bulk samples at low Fe loading (<9.0 wt %). Fe K‐edge extended XAFS oscillations of the samples with low Fe loadings were explained by assuming an isolated iron‐oxide monomer on the γ‐Al2O3 surface. 相似文献
170.
Dr. Zhengxing Qin Dr. Georgian Melinte Prof. Jean‐Pierre Gilson Prof. Maguy Jaber Prof. Krassimir Bozhilov Dr. Philippe Boullay Dr. Svetlana Mintova Prof. Ovidiu Ersen Dr. Valentin Valtchev 《Angewandte Chemie (International ed. in English)》2016,55(48):15049-15052
Zeolites are widely used in many commercial processes, mostly as catalysts or adsorbents. Understanding their intimate structure at the nanoscale is the key to control their properties and design the best materials for their ever increasing uses. Herein, we report a new and controllable fluoride treatment for the non‐discriminate extraction of zeolite framework cations. This sheds new light on the sub‐structure of commercially relevant zeolite crystals: they are segmented along defect zones exposing numerous nanometer‐sized crystalline domains, separated by low‐angle boundaries, in what were apparent single‐crystals. The concentration, morphology, and distribution of such domains analyzed by electron tomography indicate that this is a common phenomenon in zeolites, independent of their structure and chemical composition. This is a milestone to better understand their growth mechanism and rationally design superior catalysts and adsorbents. 相似文献