全文获取类型
收费全文 | 399篇 |
免费 | 20篇 |
国内免费 | 1篇 |
专业分类
化学 | 341篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 24篇 |
物理学 | 52篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 22篇 |
2020年 | 23篇 |
2019年 | 29篇 |
2018年 | 16篇 |
2017年 | 25篇 |
2016年 | 22篇 |
2015年 | 20篇 |
2014年 | 13篇 |
2013年 | 37篇 |
2012年 | 27篇 |
2011年 | 20篇 |
2010年 | 15篇 |
2009年 | 5篇 |
2008年 | 19篇 |
2007年 | 13篇 |
2006年 | 15篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 12篇 |
2002年 | 10篇 |
2001年 | 9篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1997年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 6篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1964年 | 1篇 |
1950年 | 1篇 |
1926年 | 1篇 |
1924年 | 2篇 |
1921年 | 2篇 |
排序方式: 共有420条查询结果,搜索用时 837 毫秒
91.
Similar to the antibiotic mixing strategies, which depend on reducing the worth of diffusion of the resistant bacteria to new host, in this contribution, we explicit new mixed-ligand complexes of the type [M(SMZ)2(BZM)] (M = Co(II), Ni(II) and Cu(II)) based on two drugs: sulfamethazine (SMZ) and bromazepam (BZM). The novelty aspect of the present work relies on combining two drugs in a single molecule via the synthesis of the ternary complexes. The ternary complexes were characterized by spectroscopic and analytical tools with the aid of the quantum chemical calculations. Copper(II) complex has the highest DNA intrinsic binding constant (2.20 × 105 M−1), induces extensively DNA cleavage compared to the other complexes, and exhibits the highest cytotoxicity (IC50 = 0.67 μM) against human liver cancer cell line (HepG2). Exciting, Cu(II) compound exhibits no toxicity to the nonmalignant human foetal lung fibroblast (WI-38). Alternatively, the low cytotoxicity of the Co(II) complex correlates well with the high affinity of the compound to human serum albumin (Kb = 4.58 × 105) compared to 1.93 × 105 and 2.14 × 105 M−1 for Ni (II) and Cu (II) complexes, respectively. 相似文献
92.
A new dual‐functional Cu(II) complex and its nanohybrid form encapsulated into NaY zeolite cavities were synthesized. The synthesized compounds were characterized using elemental analyses, X‐ray fluorescence, infrared, 1H NMR, electronic, electron spin resonance and mass spectra, powder X‐ray diffraction, surface area and transmission electron microscopy in addition to conductivity and magnetic susceptibility measurements. The encapsulated Cu(II) complex was catalytically tested for degradation of industrial wastewater. The decolorization and mineralization results indicate that the Cu(II) complex encapsulated into zeolite host is an effective heterogeneous catalyst for real industrial wastewater remediation. In addition, both free and encapsulated Cu(II) complexes were tested as anti‐microbial and anti‐tumour agents. The results show that the Cu(II) complex encapsulated into zeolite has a high activity (IC50 = 14.4 μg ml?1). The results of in vivo toxicity experiments indicate that the Cu(II) complex encapsulated into zeolite is a less toxic biocompatible material (LD50 = 1245 mg kg?1). The catalytic properties, cytotoxicity and toxicity of the new nanohybrid Cu(II) complex encapsulated into zeolite make it a promising eco‐friendly and biocompatible material for water remediation and biomedical applications. 相似文献
93.
Mostafa Soliman Mona A. Khorshid Ashraf M. El-Marsafy Mohamed M. Abo-Aly Tawfeek Khedr 《International journal of environmental analytical chemistry》2019,99(3):224-242
The analysis of pesticide residues in food is currently an increasingly important task. In this work, a rapid and sensitive protocol has been developed for the determination of ametoctradin, amisulbrom, bromoxynil-octanoate, chlorantraniliprole, cyhalofop-butyl, hymexazol, metaldehyde, prodiamine (dithiopyr), sulcotrione and tolfenpyrad. The extraction was done using the citrate buffer acetonitrile-based QuEChERS (quick, easy, cheap, effective, rugged and safe) sample preparation technique. Acetonitrile extracts were directly injected into the liquid chromatography-tandem mass spectrometry system, and solvent exchange was used prior to the injection in the gas chromatography system. Different exchange solvents were evaluated and a mixture of n-hexane:acetone (9:1) was chosen. Matrix effects were evaluated and a relation between the signal suppression/enhancement and the co-extracted matrix was established. The validation study was carried out on cucumber, banana and lemon matrices following SANTE/11813/2017 of the European quality control guidelines. The precision and trueness of the method were determined from recovery experiments on six replicates of spiked blank samples at 0.01, 0.05, and 0.1 mg/kg for each commodity. The range of the obtained recoveries was 70–111%, with RSD values of <18% for all the tested concentrations. The only exception was hymexazol at 0.01 mg/kg in banana and cucumber. 相似文献
94.
Research on Chemical Intermediates - TiO2 nanotubes and Ag/TiO2 nanotubes (TNT) have been synthesized by simple hydrothermal and solvothermal method and were characterized by XRD, UV, ICP, TEM,... 相似文献
95.
Wafaa S. Hamama Mona E. Ibrahim Hadeer A. Raoof Hanafi H. Zoorob 《Research on Chemical Intermediates》2017,43(11):6259-6291
This review provides a survey of the advances in the methods of formation and chemical reactivity of bicyclic [1,3,4]thiadiazole 5-5 systems containing ring-junction nitrogen over the period from 1989 to the beginning of 2017. 相似文献
96.
97.
Ali Akbar Ashkarran Seyedeh Arezoo Ahmadi AfsharSeyed Mahyad Aghigh Mona kavianipour 《Polyhedron》2010
ZrO2 nanoparticles were synthesized through arc discharge of zirconium electrodes in deionized (DI) water. X-ray diffraction (XRD) analysis of the as prepared nanoparticles indicates formation a mixture of nanocrystalline ZrO2 monoclinic and tetragonal phase structures. Transmission electron microscopy (TEM) images illustrate spherical ZrO2 nanoparticles with 7–30 nm diameter range, which were formed during the discharge process with 10 A arc current. The average particle size was found to increase with the increasing arc current. X-ray photoelectron spectroscopy (XPS) analysis confirms formation of ZrO2 at the surface of the nanoparticles. Surface area of the sample prepared at 10 A arc current, measured by BET analysis, was 44 m2/g. Photodegradation of Rhodamine B (Rh. B) shows that the prepared samples at lower currents have a higher photocatalytic activity due to larger surface area and smaller particle size. 相似文献
98.
99.
In this paper we analyze the effect of beam energy spread on cascade optical klystron undulator radiation. The analysis suggests that stronger dispersion strength needs a better beam quality in both single stage and cascade optical klystron undulator radiation. 相似文献
100.
The treatment of amines with formic acid in the presence of ZnO under solvent-free conditions brings about highly and efficient N-formylation to give the corresponding formamides in excellent yields. The N-formylation reaction not only involves mild conditions, simple operation, and high yields but also high chemoselectivity. 相似文献