全文获取类型
收费全文 | 836篇 |
免费 | 41篇 |
国内免费 | 10篇 |
专业分类
化学 | 598篇 |
晶体学 | 10篇 |
力学 | 35篇 |
数学 | 87篇 |
物理学 | 157篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 42篇 |
2021年 | 45篇 |
2020年 | 35篇 |
2019年 | 34篇 |
2018年 | 32篇 |
2017年 | 30篇 |
2016年 | 37篇 |
2015年 | 32篇 |
2014年 | 32篇 |
2013年 | 61篇 |
2012年 | 74篇 |
2011年 | 74篇 |
2010年 | 32篇 |
2009年 | 32篇 |
2008年 | 37篇 |
2007年 | 36篇 |
2006年 | 39篇 |
2005年 | 26篇 |
2004年 | 30篇 |
2003年 | 24篇 |
2002年 | 26篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1977年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1938年 | 1篇 |
排序方式: 共有887条查询结果,搜索用时 46 毫秒
881.
Khalid Hamad Abu-Shandi 《Central European Journal of Chemistry》2009,7(3):354-361
A quick method of quantitative determination of sulbactam in human plasma, using liquid chromatography-UV spectroscopy, has
been developed and validated. After derivatization with imidazole, plasma samples were treated by direct deproteinization
with acetonitrile as an extraction solvent. After ultracentrifugation, sulbactam extract was directly injected onto the LC
column. Chromatographic separation was performed on TSK Gel Super ODS (50 mm × 4.6 mm i.d., 2 μm) using methanol and phosphate buffer with tetrabutylammonium hydroxide solution as a mobile phase. Gradient elution
was employed. The method was fully validated according to the United States Food and Drug Administration requirements (linearity,
precision, trueness, quantification limit, detection limit, recovery, specificity and stability). The calibration curves were
linear within the concentration range of 0.05–4.0 μg mL−1. Good method/system precision and accuracy of the method were demonstrated.
相似文献
882.
Samy A. El-Daly Khalid A. Alamry Abdullah M. Asiri Mahmoud A. Hussein 《Journal of luminescence》2012,132(10):2747-2752
The photophysical properties such as electronic absorption, molar absorptivity, emission spectra, fluorescence quantum yield and fluorescence lifetime of N,N′-bis(4-pyridyl)-3,4:9,10-perylene bis(dicarboximide) (BPPD) have been measured in different solvents. Both electronic absorption and fluorescence spectra are not sensitive to medium polarity, while the fluorescence quantum yield (?f) is solvent dependent. The ground state geometry has been computed by using density functional theory (DFT), the transition from HOMO to LUMO from perylene core with maximum absorption at 512 nm and HOMO–LUMO energy difference equal 2.53 eV. BPPD dye undergoes molecular aggregation to dimmer or higher aggregates in dimethyl sulfoxide (DMSO). Crystalline solids of BPPD gives excimer-like emission at 676 nm. The fluorescence quenching of BPPD is also studied using hydrated ferric oxide nanoparticle (FeOOH), and the Stern–Volmer rate constants (Ksv) were calculated as 8×106 and 9.2×106 M?1 in ethanol and ethylene glycol, respectively. 相似文献
883.
Refat M. Nimer Khalid M. Sumaily Arwa Almuslat Mai Abdel Jabar Essa M. Sabi Mohammad A. Al-Muhaizea Anas M. Abdel Rahman 《Molecules (Basel, Switzerland)》2022,27(12)
Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder characterized by progressive muscle loss, leading to difficulties in movement. Mutations in the DMD gene that code for the protein dystrophin are responsible for the development of DMD disorder, where the synthesis of this protein is completely halted. Therefore, circulating dystrophin protein could be a promising biomarker of DMD disease. Current methods for diagnosing DMD have sensitivity, specificity, and reproducibility limitations. Herein, a quantitative liquid chromatography–tandem spectrometry (LC–MS/MS) technique in multiple reaction monitoring (MRM) mode was designed and validated for accurate dystrophin protein measurement in a dried blood spot (DBS). The method was successfully validated on the basis of international guidelines regarding calibration curves, precision, and accuracy. In addition, patients and healthy controls were used to test the amount of dystrophin protein circulating in DBS samples as a potential biomarker for DMD disorders. DMD patients were found to have considerably lower levels than controls. To the best of our knowledge, this is the first study to report dystrophin levels in DBS through LC–MS/MS as a diagnostic marker for DMD to the proposed MRM method, providing a highly specific and sensitive approach to dystrophin quantification in a DBS that can be applied in DMD screening. 相似文献
884.
Fatima Ezzahra El oumari Dalila Bousta Hamada Imtara Anissa Lahrichi Radouane Elhabbani Ghita El mouhri Omkulthom Al kamaly Asmaa Saleh Mohammad Khalid Parvez Andriy Grafov Tarik Sqalli Houssaini 《Molecules (Basel, Switzerland)》2022,27(13)
Ethnobotanical studies have reported the traditional medicinal uses of Acacia senegal (L.) Willd. and Argania spinosa (L.) Skeels against kidney stone formation and other chronic kidney diseases. The present work is undertaken to study the litholytic activity and the inhibiting activity of calcium oxalate crystallization by bioactive compounds identified in Argania spinosa (L.) Skeels press-cake (residue of Argan oil) and in Acacia senegal (L.) Willd. The litholytic activity was studied in vitro on cystine and uric acid stones using a porous bag and an Erlenmeyer glass. The study of the inhibiting activity of calcium oxalate crystallization, was based on temporal measurements of the optical density, registered at a 620 nm wavelength for 30 min using an ultraviolet–visible spectrophotometer. The silylation method was performed to identify phytochemicals, followed by gas chromatography coupled with mass spectrophotometry (GC/MS) analysis. The results show significant litholytic activity of Argania Spinosa press-cake hydro-ethanolic extract on uric acid and cystine stones, respectively, with dissolution rates (DR) of 86.38% and 60.42% versus 3.23% and 9.48% for the hydro-ethanolic extract of Acacia senegal exudate. Furthermore, the percentages of nucleation inhibition are 83.78% and 43.77% (p ˂ 0.05) for Argania spinosa and Acacia senegal, respectively. The results point to the detection of 17 phytochemicals in Argania spinosa press-cake extract, the majority of which are phenolic acids and have potent anti-urolithiatic action. 相似文献
885.
Mohammad Sameer Zubair Muhammad Farooq Hussain Munis Ibtisam M. Alsudays Khalid H. Alamer Urooj Haroon Asif Kamal Musrat Ali Junaid Ahmed Zimen Ahmad Houneida Attia 《Molecules (Basel, Switzerland)》2022,27(14)
Cherry is a fleshy drupe, and it is grown in temperate regions of the world. It is perishable, and several biotic and abiotic factors affect its yield. During April–May 2021, a severe fruit rot of cherry was observed in Swat and adjacent areas. Diseased fruit samples were collected, and the disease-causing pathogen was isolated on PDA. Subsequent morphological, microscopic, and molecular analyses identified the isolated pathogen as Aspergillus flavus. For the control of the fruit rot disease of cherry, iron oxide nanoparticles (Fe2O3 NPs) were synthesized in the leaf extract of Calotropis procera and characterized. Fourier transform infrared (FTIR) spectroscopy of synthesized Fe2O3 NPs showed the presence of capping and stabilizing agents such as alcohols, aldehydes, and halo compounds. X-ray diffraction (XRD) analysis verified the form and size (32 nm) of Fe2O3 NPs. Scanning electron microscopy (SEM) revealed the spinal-shaped morphology of synthesized Fe2O3 NPs while X-ray diffraction (EDX) analysis displayed the occurrence of main elements in the samples. After successful preparation and characterization of NPs, their antifungal activity against A. flavus was determined by poison technique. Based on in vitro and in vivo antifungal activity analyses, it was observed that 1.0 mg/mL concentration of Fe2O3 can effectively inhibit the growth of fungal mycelia and decrease the incidence of fruit rot of cherry. The results confirmed ecofriendly fungicidal role of Fe2O3 and suggested that their large-scale application in the field to replace toxic chemical fungicides. 相似文献
886.
Zakariyya Uba Zango John Ojur Dennis A. I. Aljameel Fahad Usman Mohammed Khalil Mohammed Ali Bashir Abubakar Abdulkadir Saja Algessair Osamah A. Aldaghri Khalid Hassan Ibnaouf 《Molecules (Basel, Switzerland)》2022,27(15)
Successful synthesis of ZnO-chitosan nanocomposites was conducted for the removal of methylene blue from an aqueous medium. Remarkable performance of the nanocomposites was demonstrated for the effective uptake of the dye, thereby achieving 83.77, 93.78 and 97.93 mg g−1 for the chitosan, 5 wt.% ZnO-Chitosan and 10 wt.% ZnO-Chitosan, respectively. The corresponding adsorption efficiency was 88.77, 93.78 and 97.95 for the chitosan, 5 wt.% ZnO-Chitosan and 10 wt.% ZnO-Chitosan, respectively. Upon regeneration, good reusability of the nanocomposites was manifested for the continuous removal of the dye up to six consecutive cycles. The adsorption process was kinetically described by a pseudo-first order model, while the isotherms were best fitted by the Langmuir model. 相似文献
887.
Natasha Bokhari Abida Yasmeen Asif Ali Hamad Khalid Rong Wang Mustehsan Bashir Faiza Sharif 《Macromolecular bioscience》2023,23(9):2300039
Meshes from natural silk are hand knitted and surface functionalized to facilitate hernia repair and other load bearing, tissue applications. Purified organic silk is - hand knitted and then coated with chitosan (CH)/bacterial cellulose (BC) blend polymer using four phytochemicals such as pomegranate (PG) peel, Nigella sativa (NS) seed, Licorice root (LE), and Bearberry leaf extracts (BE) separately. Characterizations using GCMS analysis shows the presence of bioactive chemicals in the extracts. Scanning electron microcopy (SEM) shows that the surface is coated with the composite polymer t. Fourier transform infrared spectroscopy (FTIR) shows significant elements found in CH, BC, and phytochemicals in plant extracts with no chemical changes. Tensile strength of the coated meshes is higher to support tissue as implants. The release kinetics suggest sustained release of phytochemical extracts. In vitro studies confirmed the noncytotoxic, biocompatible, wound healing potential of the meshes. Furthermore, gene expression analysis of 3-wound healing genes shows marked increase in the in vitro cell cultures due to the presence of extracts. These results suggest that the composite meshes can efficiently support hernia closure while facilitating wound/tissue healing and combating bacterial infections. Therefore, these meshes can be good candidates for fistula and cleft palate repair. 相似文献