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排序方式: 共有468条查询结果,搜索用时 31 毫秒
461.
Yeyun Zhao Dr. Jianhui Yang Chao Liang Zhongjie Wang Yongfeng Zhang Gengchen Li Jiamin Qu Xi Wang Yahui Zhang Dr. Peng Sun Prof. Jianbing Shi Prof. Bin Tong Prof. Hai-Yan Xie Prof. Zhengxu Cai Prof. Yuping Dong 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(5):e202317431
Organic near-infrared room temperature phosphorescence (RTP) materials offer remarkable advantages in bioimaging due to their characteristic time scales and background noise elimination. However, developing near-infrared RTP materials for deep tissue imaging still faces challenges since the small band gap may increase the non-radiative decay, resulting in weak emission and short phosphorescence lifetime. In this study, fused-ring pyrrole-based structures were employed as the guest molecules for the construction of long wavelength emissive RTP materials. Compared to the decrease of the singlet energy level, the triplet energy level showed a more effectively decrease with the increase of the conjugation of the substituent groups. Moreover, the sufficient conjugation of fused ring structures in the guest molecule suppresses the non-radiative decay of triplet excitons. Therefore, a near-infrared RTP material (764 nm) was achieved for deep penetration bioimaging. Tumor cell membrane is used to coat RTP nanoparticles (NPs) to avoid decreasing the RTP performance compared to traditional coating by amphiphilic surfactants. RTP NPs with tumor-targeting properties show favorable phosphorescent properties, superior stability, and excellent biocompatibility. These NPs are applied for time-resolved luminescence imaging to eliminate background interference with excellent tissue penetration. This study provides a practical solution to prepare long-wavelength and long-lifetime organic RTP materials and their applications in bioimaging. 相似文献
462.
《中国化学快报》2021,32(8):2423-2426
In the crystal engineering area,it is important to clearly demonstrating the relationship of structure and certain functionality.Herein,we present the study of the relationship of structure with phosphorescent nature for two new room temperature phosphorescence(RTP) coordination polymers(CPs).[Pb(FDA)(H_2 O)](1) and [NH_3(CH_3)NH_2(CH_3)_2][Pb_4(FDA)_5](2),where H_2 FDA is 2,5-furandicarboxylic acid,have been synthesized by solvothermal method using different solvents and Pb~(2+) sources and characterized by microanalysis,powderX-ray diffraction(PXRD),thermogravimetric(TG),IR and UV-vis spectra.The Pb~(2+)ions adopt bicapped triangle prism coordination sphere in 1 and 2,which are connected together via FDA~(2-) ligands into bilayer structure in 1 while pillared-layer framework in 2.The FDA~(2-) ligands show different bridging modes in 1 and 2,leading to distinct coordination interactions between Pb~(2+) ion and FDA~(2-) ligand in both CPs.Both 1 and 2 emit ligand-centered RTP due to the heavy atom of Pb~(2+) ion,with a lifetime and quantum yield of 0.62 ms and 14.9% in 1 versus 1.69 ms and 15.7% in 2.The emission peak shows significant redshift(79 nm) in 2 regarding 1,which arises from their distinction of coordination interactions between Pb~(2+) ion and FDA~(2-) ligand in both CPs. 相似文献
463.
464.
Xiaoqing Song Guang Lu Yi Man Dr. Jing Zhang Dr. Shuo Chen Dr. Chunmiao Han Prof. Hui Xu 《Angewandte Chemie (International ed. in English)》2023,62(21):e202300980
Organic room temperature phosphorescence (RTP) attracts extensive attentions, but still faces the challenge of achieving both high RTP efficiencies (ηRTP) and long lifetimes (τRTP), due to the intrinsic contradiction between triplet radiation and stabilization. In this work, we developed three carbazole-triphenylphosphine hybrids named xCzTPP, in which phosphine groups provide nonbonding electrons and steric hindrance to modulate intermolecular p-π and π-π interactions. With the rational orientations and spatial positions of functional groups, para-substituted pCzTPP achieves high ηRTP over 10 % and more than twofold increased τRTP (>600 ms), compared to ortho- and meta- isomers. Theoretical simulation and photophysical investigation indicate that the strongest intermolecular p-π and π-π electronic interplays of pCzTPP harmonize high transition probability of 3pπ state and triplet stability of 3ππ state, reflecting the p-π and π-π synergy in RTP process. 相似文献
465.
本文对近年来音乐厅音质设计中若干问题的进展作一述评。(1)在已建立的众多独立音质参量基础上,如何作出大厅综合评价,就需要考虑到它们的互动性和贡献权,方法学将成为关键。(2)空间感已确认由声源视在展宽度ASW和听者环绕感LEV组成,对于影响两者的诸多复杂因素有了较深入研究,这声场中的细节又将如何与大厅设计相联系亦备受关注。(3)听众及座椅吸声这个老问题有了新的研究成果,对于空、满场的声学关系已积累了更多资料,使大厅音质的估算更为精确可靠。(4)常说扩散对大厅音质很重要,但其主观效应仍然处于玄虚状态,一些新的主观试听实验结果还不足以说明问题。 相似文献
466.
Weiguo Qiao Ming Yao Jingwen Xu Haiyan Peng Jianlong Xia Xiaolin Xie Zhong'an Li 《Angewandte Chemie (International ed. in English)》2023,62(50):e202315911
Accidentally, it was found that triphenylamine (TPA) from commercial sources shows ultralong yellow-green room temperature phosphorescence (RTP) like commercial carbazole, which however disappears for lab-synthesized TPA with high purity. Herein, we for the first time identify the impurity types that cause RTP of commercial TPA, which are two N, N-diphenyl-naphthylamine isomers. Due to similar molecular polarity and very trace amount (≈0.8 ‰, molar ratio), these naphthyl substituted impurities can be easily overlooked. We further show that even at an extremely low amount (1000000 : 1, mass ratio) of impurities, RTP emission is still generated, attributed to the triplet-to-triplet energy transfer mechanism. Notably, this doping strategy is also applicable to the triphenylphosphine and benzophenone host systems, of which strong RTP emission can be activated by simply doping the corresponding naphthyl substituted analogues into them. This work therefore provides a general and efficient host/guest strategy toward high performance and diverse organic RTP materials. 相似文献
467.
公文办理是一项规范性、政策性和科学性很强的工作,公文办理工作的效率和质量,直接影响各项政策、措施的贯彻落实。本文提出在机关办公部门设立阅文室以确保文件管理有序、运转安全和完整。 相似文献
468.
《Arabian Journal of Chemistry》2023,16(4):104552
Heavy metals (HMs), pollution of major environmental matrices and its attendant effects on human health and the environment, continue to generate huge scientific interest, particularly in monitoring and detection. Herein, the optical property of carboxymethyl cellulose stabilized silver nanoparticles (CMC-AgNPs), supported with ascorbic acid, is exploited as a colorimetric probe for the detection of toxic Au3+ ion in solution. The as-synthesized CMC-AgNPs showed sharp absorption maximum at 403 nm, with sparkling yellow color and average particles size distribution less than 10 nm. It was further characterized using ATR-FTIR, TEM, FESEM/EDS, XRD and DLS/zeta potential analyzer. Au3+ ion detection strategy involves the addition of ascorbic acid (AA) to a pH adjusted CMC-AgNPs, followed by the analyte addition. AA would facilitate the reduction of Au3+ on CMC-AgNPs (seed), with resultant color perturbations from light yellow to yellow, orange, ruby red and purple red, under 8 min incubation, at room temperature (RT). The CMC-AgNPs could also serve as a catalyst, by promoting AA mediated reduction of Au3+, in-situ. Moreover, we propose, that the color and the absorption spectra change is attributed to the deposition of gold nanoparticles (AuNPs), on the CMC-AgNPs/AA probe, to form (CMC-Ag@Au) nanostructures, depending on the analyte concentration. Absorbance ratio (A540/A403) showed good linearity with Au3+ concentration from 0.25 to 100.0 µM, and an estimated LOD of 0.061 µM. The assay was applied to Au3+ detection in environmental wastewater sample, showing satisfactory real sample detection potentiality. 相似文献