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排序方式: 共有677条查询结果,搜索用时 15 毫秒
641.
Mohamad Faisal Abdul Karim Ahmad Izani Md Ismail Hoe Bee Ching 《Chaos, solitons, and fractals》2009,41(5):2847-2853
Hantaviruses are a group of viruses which have been identified as being responsible for the outbreak of diseases such as the hantavirus pulmonary syndrome. In an effort to understand the characteristics and dynamics of hantavirus infection, mathematical models based on differential equations have been developed and widely studied. However, such models neglect the local characteristics of the spreading process and do not include variable susceptibility of individuals. In this paper, we develop an alternative approach based on cellular automata to analyze and study the spatiotemporal patterns of hantavirus infection. 相似文献
642.
Wan Mohamad Ikhmal Wan Mohamad Kamaruzzaman Maria Fazira Mohd Fekeri Nursabrina Amirah Mohd Nasir Nur Aiman Syafiq Mohd Hamidi Mohamad Zahid Baharom Azila Adnan Muhamad Syaizwadi Shaifudin Wan Rafizah Wan Abdullah Wan Mohd Norsani Wan Nik Fariza Hanim Suhailin Khamirul Amin Matori Chen Soo Kien Mohd Hafiz Mohd Zaid Mohd Sabri Mohd Ghazali 《Molecules (Basel, Switzerland)》2021,26(11)
With the trend for green technology, the study focused on utilizing a forgotten herb to produce an eco-friendly coating. Andrographis paniculata or the kalmegh leaves extract (KLE) has been investigated for its abilities in retarding the corrosion process due to its excellent anti-oxidative and antimicrobial properties. Here, KLE was employed as a novel additive in coatings and formulations were made by varying its wt%: 0, 3, 6, 9, and 12. These were applied to stainless steel 316L immersed in seawater for up to 50 days. The samples were characterized and analyzed to measure effectiveness of inhibition of corrosion and microbial growth. The best concentration was revealed to be 6 wt% KLE; it exhibited the highest performance in improving the ionic resistance of the coating and reducing the growth of bacteria. 相似文献
643.
This paper studies time-delayed switched systems that include both stable and unstable modes. By using multiple Lyapunov-functions technique and a dwell-time approach, several criteria on exponential stability for both linear and nonlinear systems are established. It is shown that by suitably controlling the switching between the stable and unstable modes, exponential stabilization of the switched system can be achieved. Some examples and numerical simulations are provided to illustrate our results. 相似文献
644.
Saleh M. Al‐Mousawi Mohammad A. Mohammad Mohamad H. Elnagdi 《Journal of heterocyclic chemistry》2001,38(4):989-991
While 3(5)‐aminopyrazole reacts with enaminonitrile to yield pyrazolo[1,5‐a]pyrimidines, 3‐amino‐5‐pyrazolone reacts with the same reagents to yields pyrazolo[3,4‐b]pyridines. 相似文献
645.
Lei Yang Cheng‐Zhu Yin Mohamad Akbar Ali Chao‐Yang Dong Xin‐Miao Xie Xiang‐Ping Wu Jie Mao Yong‐Xia Wang Yang Yu Ling‐Hai Xie Lin‐Yi Bian Jian‐Min Bao Xue‐Qin Ran Wei Huang 《中国化学》2019,37(9):915-921
Organic semiconductor materials with low reorganization energy have various applications such as in organic light‐emitting diodes (OLEDs), organic field‐effect transistor (OFETs) and organic solar cells (OSCs). In this work, we have designed a new class of gridspiroarenes (GS‐SFX and GS‐SITF) with #‐shaped structures, which have novel crisscross geometrical structures compared to widely used spirocyclic arenes—SFX and SITF. The structure electronic properties, adiabatic ionization potentials (IPa), adiabatic electron affinities (EAa) and reorganization energies (λ) of GS‐SFX and GS‐SITF have been calculated using density functional theory (DFT) method. The calculated HOMO and LUMO spatial distributions suggest that GS‐SFX and GS‐SITF have better transport properties. The noncovalent interaction analysis shows the weak intramolecular interactions between their arms. The results indicate that the reorganization energies of GS‐SFX and GS‐SITF are significantly reduced compared to the dimer structures—DSFX and DSITF. Furthermore, the GS‐SITF1 which is one of the isomers of GS‐SITF exhibits the lowest values for λ(h) (0.067 eV) and λ(e) (0.153 eV). Therefore, we believe the predicted structure, electronic property, and reorganization energy are good indicator for transport materials. This work has systematically studied the effect of gridization, which provides insights to design organic semiconductor materials with excellent charge transport properties. 相似文献
646.
Paulo S. Santos Mohamad G. Abiad Marcelo A. Carignano Osvaldo H. Campanella 《Rheologica Acta》2012,51(1):3-11
The rheological behavior of Dibenzylidene D-Sorbitol (DBS) gels formed in ethylene glycol, glycerol, mineral oil, ethanol,
and chlorobenzene was studied using oscillatory squeezing flow viscometry. The storage (G
′) and loss (G
″) moduli were measured as a function of gellant concentration (0.5–2 w/w) and type of solvent. As expected greater values of gel strength (G
′) were observed for gels containing higher concentrations of DBS. In addition, both storage and loss moduli of 2% systems
were mostly frequency independent over the studied range, whereas 0.5% gels did exhibit some degree of dependence. We also
found that the solvent plays an important role in the properties of the gels. Among the parameters that affect the viscoelastic
properties of DBS gels, the solvent polarity and its ability to form hydrogen bonding may have significant effects on the
gel rheology. 相似文献
647.
Xuqiao Hu Hongyan Li Tiffany Ka-Yan Ip Yam Fung Cheung Mohamad Koohi-Moghadam Haibo Wang Xinming Yang Daniel N. Tritton Yuchuan Wang Yi Wang Runming Wang Kwan-Ming Ng Hua Naranmandura Eric Wai-Choi Tse Hongzhe Sun 《Chemical science》2021,12(32):10893
The mechanisms of action of arsenic trioxide (ATO), a clinically used drug for the treatment of acute promyelocytic leukemia (APL), have been actively studied mainly through characterization of individual putative protein targets. There appear to be no studies at a system level. Herein, we integrate metalloproteomics through a newly developed organoarsenic probe, As-AC (C20H17AsN4O3S2) with quantitative proteomics, allowing 37 arsenic binding and 250 arsenic regulated proteins to be identified in NB4, a human APL cell line. Bioinformatics analysis reveals that ATO disrupts multiple physiological processes, in particular, chaperone-related protein folding and cellular response to stress. Furthermore, we discover heat shock protein 60 (Hsp60) as a vital target of ATO. Through biophysical and cell-based assays, we demonstrate that ATO binds to Hsp60, leading to abolishment of Hsp60 refolding capability. Significantly, the binding of ATO to Hsp60 disrupts the formation of Hsp60-p53 and Hsp60-survivin complexes, resulting in degradation of p53 and survivin. This study provides significant insights into the mechanism of action of ATO at a systemic perspective, and serves as guidance for the rational design of metal-based anticancer drugs.A highly selective organoarsenic fluorescent probe As-AC and quantitative proteomics were employed to track arsenic-binding and regulating proteins in live leukemia cells. Hsp60 was validated as a new target of ATO. 相似文献
648.
Transition metal complexes of a hydrazone–oxime ligand containing the isonicotinoyl moiety: Synthesis,characterization and microbicide activities
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Complexes of VO2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Ru3+ and UO22+ with (3‐(hydroxyimino)butan‐2‐ylidene)isonicotinohydrazide were synthesized and characterized using physical and spectral methods. Analytical data revealed that the complexes formed in 1:1 or 1:2 metal–ligand ratios. Spectral studies showed that the ligand bonded to the metal ion in neutral tridentate, monobasic tridentate or monobasic bidentate fashion through azomethine nitrogen atom, protonated/deprotonated imine oxime group and/or ketonic/enolic carbonyl group. From the electronic spectral data together with magnetic susceptibility values a square planar, tetrahedral or distorted octahedral structure can be proposed for all complexes. Electron spin resonance spectra for Cu2+ complexes ( 2 – 4 ) revealed axial symmetry with g|| > g⊥ > ge, indicating distorted octahedral or square planar structures and the unpaired electron exists in a orbital with marked covalent bond feature. The prepared complexes showed good to excellent biological activity, and the most active complexes against Aspergillus niger were 4 and 9 with zone of inhibition of 25 and 23 mm, respectively. Complexes 10 and 11 showed interesting activity against Escherichia coli with zone of inhibition of 44 and 32 mm, respectively. 相似文献
649.
New mixed valence gold(III/I) salt containing two complexes [Au(Me2phen)Br2][AuBr2] (1) was prepared from the reaction of AuBr3 and 5,6-dimethyl-1,10-phenanthroline (Me2phen) in a mixture of methanol and acetonitrile. Suitable crystals of 1 for X-ray diffraction measurement were obtained by slow evaporation of the resulted red solution at room temperature. This complex was characterized by spectral methods (IR, UV–Vis and 1H NMR), elemental analysis and single-crystal X-ray diffraction. The X-ray structural analysis indicated that the asymmetric unit of 1 contains one [Au(Me2phen)Br2]+ cation and two half anions of [AuBr2]ˉ. Furthermore, the packing diagram of this complex, 3-D structure stabilized by intermolecular Au…Br and Au…π interactions and intermolecular C–H···Br hydrogen bonds. The experimental investigations on complex have been accompanied computationally by the density functional theory (DFT) and time-dependent DFT calculations. The nature of the Au–N bonds was investigated using quantum theory of atoms in molecules. Moreover, natural bond orbital analysis carried out to obtain hyper-conjugative interactions and electron delocalization on the complex. 相似文献
650.
Stefano DallAcqua Kouadio Ibrahime Sinan Irene Ferrarese Stefania Sut Kouadio Bene Mohamad Fawzi Mahomoodally Nabeelah Bibi Sadeer Gunes Ak Gokhan Zengin 《Molecules (Basel, Switzerland)》2020,25(23)
Breynia retusa (Dennst.) Alston (also known as Cup Saucer plant) is a food plant with wide applications in traditional medicine, particularly in Ayurveda. Extracts obtained with four solvents (dichloromethane, methanol, ethyl acetate and water), from three plant parts, (fruit, leaf and bark) were obtained. Extracts were tested for total phenolic, flavonoid content and antioxidant activities using a battery of assays including 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), cupric reducing antioxidant capacity (CUPRAC), total antioxidant capacity (TAC) (phosphomolybdenum) and metal chelating. Enzyme inhibitory effects were investigated using acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, α-amylase and α-glucosidase as target enzymes. Results showed that the methanolic bark extract exhibited significant radical scavenging activity (DPPH: 202.09 ± 0.15; ABTS: 490.12 ± 0.18 mg Trolox equivalent (TE)/g), reducing potential (FRAP: 325.86 ± 4.36: CUPRAC: 661.82 ± 0.40 mg TE/g) and possessed the highest TAC (3.33 ± 0.13 mmol TE/g). The methanolic extracts were subjected to LC-DAD-MSn and NMR analysis. A two-column LC method was developed to separate constituents, allowing to identify and quantify forty-four and fifteen constituents in bark and fruits, respectively. Main compound in bark was epicatechin-3-O-sulphate and isolation of compound was performed to confirm its identity. Bark extract contained catechins, procyanidins, gallic acid derivatives and the sulfur containing spiroketal named breynins. Aerial parts mostly contained flavonoid glycosides. Considering the bioassays, the methanolic bark extract resulted a potent tyrosinase (152.79 ± 0.27 mg kojic acid equivalent/g), α-amylase (0.99 ± 0.01 mmol acarbose equivalent ACAE/g) and α-glucosidase (2.16 ± 0.01 mmol ACAE/g) inhibitor. In conclusion, methanol is able to extract the efficiently the phytoconstituents of B. retusa and the bark is the most valuable source of compounds. 相似文献