全文获取类型
收费全文 | 669篇 |
免费 | 32篇 |
国内免费 | 14篇 |
专业分类
化学 | 464篇 |
晶体学 | 6篇 |
力学 | 25篇 |
综合类 | 2篇 |
数学 | 50篇 |
物理学 | 168篇 |
出版年
2024年 | 4篇 |
2023年 | 6篇 |
2022年 | 19篇 |
2021年 | 57篇 |
2020年 | 28篇 |
2019年 | 35篇 |
2018年 | 49篇 |
2017年 | 37篇 |
2016年 | 33篇 |
2015年 | 26篇 |
2014年 | 27篇 |
2013年 | 57篇 |
2012年 | 56篇 |
2011年 | 57篇 |
2010年 | 33篇 |
2009年 | 24篇 |
2008年 | 29篇 |
2007年 | 21篇 |
2006年 | 18篇 |
2005年 | 13篇 |
2004年 | 8篇 |
2003年 | 12篇 |
2002年 | 11篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1976年 | 3篇 |
1973年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有715条查询结果,搜索用时 31 毫秒
31.
Highly sensitive FRET-based fluorescence immunoassay for aflatoxin B1 using cadmium telluride quantum dots 总被引:1,自引:0,他引:1
Roya Zekavati Shahabeddin Safi Seyed Jamal Hashemi Tavoos Rahmani-Cherati Meisam Tabatabaei Afshin Mohsenifar Mansour Bayat 《Mikrochimica acta》2013,180(13-14):1217-1223
We report on a competitive immunoassay for the determination of aflatoxin B1 using fluorescence resonance energy transfer (FRET) from anti-aflatoxin B1 antibody (immobilized on the shell of CdTe quantum dots) to Rhodamine 123 (Rho 123-labeled aflatoxin B1 bound to albumin). The highly specific immunoreaction between the antibody against aflatoxin B1 on the QDs and the labeled-aflatoxin B1 brings the Rho 123 fluorophore (acting as the acceptor) and the QDs (acting as the donor) in close spatial proximity and causes FRET to occur upon photoexcitation of the QDs. In the absence of unlabeled aflatoxin B1, the antigen-antibody complex is stable, and strong emission resulting from the FRET from QDs to labeled aflatoxin B1 is observed. In the presence of aflatoxin B1, it will compete with the labeled aflatoxin B1-albumin complex for binding to the antibody-QDs conjugate so that FRET will be increasingly suppressed. The reduction in the fluorescence intensity of the acceptor correlates well with the concentration of aflatoxin B1. The feasibility of the method was established by the detection of aflatoxin B1 in spiked human serum. There is a linear relationship between the increased fluorescence intensity of Rho 123 with increasing concentration of aflatoxin B1 in spike human serum, over the range of 0.1–0.6 μmol·mL?1. The limit of detection is 2?×?10?11 M. This homogeneous competitive detection scheme is simple, rapid and efficient, and does not require excessive washing and separation steps. Figure
A nanobiosensor has been fabricated based on a competitive immunoassay for the determination of aflatoxin B1 using fluorescence resonance energy transfer (FRET). In the presence of aflatoxin B1, it will compete with the labeled aflatoxin B1-albumin complex for binding to the antibody-QDs conjugate so that FRET will be increasingly suppressed. 相似文献
32.
The synthesis and characterization of two new aluminate(Ⅲ) complexes with general formula K[AlCl3X] are reported. These compounds derived from aluminate trichloride and related salts. Potassium trichlorothiocyanoaluminate, PCTA, and potassium trichlorocyanatoalu-minate, PCCA, are two new ionic aluminate complexes. They can be easily synthesized in a nearly quantitative yield by using the direct reaction of AlCl3 and KX. The complexes were characterized by physico-chemical and spectroscopic methods. Theoretical calculations have been used for the extraction of structural and spectroscopic data of these new synthesized complexes. The antibacterial activities of such compounds were studied against the Staphylococcus aureus, Escherichia coli, Staphylococcus Epidermidis, Estreptococo B and Shigella. 相似文献
33.
Ismail Muhammad Javed Salma Kazim Muhammad Razaq Abdur Hussain Ejaz Attia-tul-Wahab Ali Sajjad Choudhary Muhammad Iqbal 《Chemistry of Natural Compounds》2022,58(4):637-643
Chemistry of Natural Compounds - One new and seven known secondary metabolites 1–8 were isolated, and the nematocidal and insecticidal activities of major compounds from Tanacetum... 相似文献
34.
Qamar Adnan Anwar Zahid Ali Hassan Shaukat Rabia Imran Shahid Arshad Attique Ali Hafiz Muhammad Korakianitis Theodosios 《Journal of Thermal Analysis and Calorimetry》2022,147(1):23-46
Journal of Thermal Analysis and Calorimetry - Nanofluids have recently attracted attention of many researchers due to their growing potential applications in heat transfer devices. They possess... 相似文献
35.
Lahcen Hssaini Francisca Hernandez Manuel Viuda-Martos Jamal Charafi Rachid Razouk Karim Houmanat Rachida Ouaabou Said Ennahli Driss Elothmani Ilham Hmid Marie Laure Fauconnier Hafida Hanine 《Molecules (Basel, Switzerland)》2021,26(9)
In the present study, chromatic coordinates, phenolic acids, flavonoids and antioxidant capacity assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate (ABTS) and lipid peroxidation inhibition capacity (LPIC) essays and their relative IC50 were investigated in 25 fig cultivars growing in Morocco. The aims of this study were to determine (i) the variation in these compounds among light and dark-colored cultivars, (ii) their partitioning between fruit peel and pulp and (iii) to display network connections among these variables. Twelve phenolic compounds (PCs) were isolated in peel extract versus eight in pulp samples. Anthocyanins, mainly cyanidin-3,5-diglucoside and cyanidin-3-O-rutinoside, were the predominant compounds in peels, where the mean concentrations were 75.90 ± 18.76 and 77.97 ± 18.95 µg/g dw, respectively. On the other hand, (−)-epicatechin and cyanidin-3-O-rutinoside were the major compounds in the pulp extracts, where the mean values were 5.23 ± 4.03 and 9.01 ± 5.67 µg/g dw, respectively. A two-dimensional hierarchically clustered heatmap was applied to the dataset to explore correlations in the dataset and similarities between cultivars, without dimensionality reduction. Results showed that anthocyanins, particularly pelargonidin-3-O-rutinoside, cyanidin-3,5-diglucoside and cyanidin-3-O-rutinoside, were the main contributors to the peels’ free radical scavenging capacity. This capacity was particularly higher in the peel of dark-colored figs compared to the fruit pulp. The local cultivar “INRA 1301” showed the most promising phenolic profile due to its very high levels of almost all detected PCs, especially (−)-epicatechin, quercetin-3-O-rutinoside, quercetin-3-O-glucoside, cyanidine-3,5-diglucoside, cyanidine-3-O-rutinoside and pelargonidin-3-O-rutinoside (54.66, 141.08, 35.48, 494.08, 478.66, 12.56 µg/g dw, respectively). Having the darkest figs in the collection (L* = 25.72, c* = 22.09 and h° = 20.99), this cultivar has also combined promising IC50 values, which were of 19.85, 40.58 and 124.78 µg/mL for DPPH, ABTS and LPIC essays, respectively. 相似文献
36.
Syed Sarim Imam Sultan Alshehri Mohammad A. Altamimi Afzal Hussain Wajhul Qamar Sadaf Jamal Gilani Ameeduzzafar Zafar Nabil K. Alruwaili Saleh Alanazi Bjad K. Almutairy 《Molecules (Basel, Switzerland)》2021,26(11)
The present research work is designed to prepare and evaluate piperine liposomes and piperine–chitosan-coated liposomes for oral delivery. Piperine (PPN) is a water-insoluble bioactive compound used for different diseases. The prepared formulations were evaluated for physicochemical study, mucoadhesive study, permeation study and in vitro cytotoxic study using the MCF7 breast cancer cell line. Piperine-loaded liposomes (PLF) were prepared by the thin-film evaporation method. The selected liposomes were coated with chitosan (PLFC) by electrostatic deposition to enhance the mucoadhesive property and in vitro therapeutic efficacy. Based on the findings of the study, the prepared PPN liposomes (PLF3) and chitosan coated PPN liposomes (PLF3C1) showed a nanometric size range of 165.7 ± 7.4 to 243.4 ± 7.5, a narrow polydispersity index (>0.3) and zeta potential (−7.1 to 29.8 mV). The average encapsulation efficiency was found to be between 60 and 80% for all prepared formulations. The drug release and permeation study profile showed biphasic release behavior and enhanced PPN permeation. The in vitro antioxidant study results showed a comparable antioxidant activity with pure PPN. The anticancer study depicted that the cell viability assay of tested PLF3C2 has significantly (p < 0.001)) reduced the IC50 when compared with pure PPN. The study revealed that oral chitosan-coated liposomes are a promising delivery system for the PPN and can increase the therapeutic efficacy against the breast cancer cell line. 相似文献
37.
Ziyat Hamid Elmzioui Souad Naciri Bennani Mohammed Houssaini Jamal Allaoui Safae Arhzaf Said 《Research on Chemical Intermediates》2021,47(6):2605-2627
Research on Chemical Intermediates - The objective of this work is to test the effectiveness of hydrotalcite as an adsorbent for the retention of nitrate and nitrite ions and to study the influence... 相似文献
38.
39.
Nathalie Azaroual Jamal El Bakali Delphine Le Broc Carole Deghaye Amaury Farce Philippe Chavatte Régis Millet Claude Vaccher Emmanuelle Lipka-Belloli 《Journal of inclusion phenomena and macrocyclic chemistry》2014,78(1-4):265-274
Three selective CB2 cannabinoid receptor ligands have recently been discovered to be promising anti-inflammatory agents but their low water solubility hinder their per os administration. The popularity of the cyclodextrins, from a pharmaceutical standpoint lies on their ability to interact with poorly water-soluble drugs and improve their solubility. Herein, three experimental approaches for calculating the stability constant of complexes between the selective CB2 ligands and either the β-CD or the HP-β-CD, were tested: nuclear magnetic resonance, micellar electrokinetic chromatography and high performance liquid chromatography in reversed phase. In NMR studies the calculated K values were relatively high and were between 1486 and 3571 M?1 with β-CD. With HP-β-CD they were between 1203 and 2650 M?1. Concerning the two others techniques the K values were found lower. In MECK studies with β-CD they were between 308 and 792 M?1 and with HP-β-CD between 124 and 764 M?1. Finally in RP-HPLC studies with β-CD, they were between 539 and 1144 M?1 and with HP-β-CD between 196 and 396 M?1. These calculated constants suggest that a complexation phenomenon occurs. A model for inclusion of one of the CB2 ligands in the β-CD was then proposed from molecular modeling studies. 相似文献
40.
Nosrati Sahar Molavipordanjani Sajjad Emami Saeed Abedi Seyed Mohammad Talebpour Amiri Fereshteh Hosseinimehr Seyed Jalal 《Journal of Radioanalytical and Nuclear Chemistry》2020,323(1):205-211
This study presents [99mTc]BPTG-1 and [99mTc]BPTG-2 for glioblastoma imaging. In vitro cellular uptakes of these radiotracers were examined in SKOV-3, MCF-7, U87-MG, HT-29, and A549 cell lines. U87-MG cell line displayed the highest radiotracers uptakes. Biodistribution study in U87-MG tumor bearing mice revealed higher uptake of radiotracers in tumor than muscle and brain. Liver, intestine, and kidneys displayed the highest radioactivity uptakes. The main route of radiotracers elimination was hepatobiliary. Due to the brain uptake of these radiotracers, they are promising radiotracers for future studies in the diagnosis of glioblastoma.
相似文献