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211.
A far-red emitting probe for unambiguous detection of mobile zinc in acidic vesicles and deep tissue
Pablo Rivera-Fuentes Alexandra T. Wrobel Melissa L. Zastrow Mustafa Khan John Georgiou Thomas T. Luyben John C. Roder Kenichi Okamoto Stephen J. Lippard 《Chemical science》2015,6(3):1944-1948
Imaging mobile zinc in acidic environments remains challenging because most small-molecule optical probes display pH-dependent fluorescence. Here we report a reaction-based sensor that detects mobile zinc unambiguously at low pH. The sensor responds reversibly and with a large dynamic range to exogenously applied Zn2+ in lysosomes of HeLa cells, endogenous Zn2+ in insulin granules of MIN6 cells, and zinc-rich mossy fiber boutons in hippocampal tissue from mice. This long-wavelength probe is compatible with the green-fluorescent protein, enabling multicolor imaging, and facilitates visualization of mossy fiber boutons at depths of >100 μm, as demonstrated by studies in live tissue employing two-photon microscopy. 相似文献
212.
Mustafa Aghazadeh Mehdi Ghaemi Behrouz Sabour Somayeh Dalvand 《Journal of Solid State Electrochemistry》2014,18(6):1569-1584
Well-dispersed nanoparticles of nickel hydroxide were prepared via a simple electrochemical method. Electrodeposition experiments were performed from 0.005 M Ni(NO3)2 bath at a constant current density of 0.1 mA cm?2 on the steel cathode for 1 h. Recording the potential values during the deposition process revealed that the reduction of water has major role in the base electrogeneration at the applied conditions. The obtained deposit was characterized by the X-ray diffraction (XRD), infrared (IR), differential scanning calorimeter–thermogravimetric analysis, carbon–nitrogen–hydrogen (CHN), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The CHN, XRD, and IR analyses showed that the obtained deposit has α phase of Ni(OH)2 with intercalated nitrate ions in its structure. Morphological characterization by SEM and TEM revealed that the prepared α-Ni(OH)2 is composed of well-dispersed ultrafine particles with the size of about 5 nm. The supercapacitive performance of the prepared nanoparticles was analyzed by means of cyclic voltammetry and galvanostatic charge–discharge tests. The electrochemical measurements showed an excellent supercapacitive behavior of the prepared α-Ni(OH)2 nanoparticles. It was also observed that the α-Ni(OH)2 ultrafine particles have better electrochemical characteristic and supercapacitive behavior than β-Ni(OH)2 ultrafine nanoparticles, including less positive charging potential, lower E a???E c value, better reversibility, higher E OER???E a, higher utilization of active material, higher proton diffusion coefficient, greater discharge capacity, and better cyclability. These results make the α-Ni(OH)2 nanoparticles as an excellent candidate for the supercapacitor materials. 相似文献
213.
Robust Inclusion Complexes of Crown Ether Fused Tetrathiafulvalenes with Li+@C60 to Afford Efficient Photodriven Charge Separation 下载免费PDF全文
Dr. Mustafa Supur Yuki Kawashima Dr. Karina R. Larsen Dr. Kei Ohkubo Prof. Jan O. Jeppesen Prof. Shunichi Fukuzumi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(43):13976-13983
Inclusion complexes of benzo‐ and dithiabenzo‐crown ether functionalized monopyrrolotetrathiafulvalene (MPTTF) molecules were formed with Li+@C60 ( 1? Li+@C60 and 2? Li+@C60). The strong complexation has been quantified by high binding constants that exceed 106 M ?1 obtained by UV/Vis titrations in benzonitrile (PhCN) at room temperature. On the basis of DFT studies at the B3LYP/6‐311G(d,p) level, the orbital interactions between the crown ether moieties and the π surface of the fullerene together with the endohedral Li+ have a crucial role in robust complex formation. Interestingly, complexation of Li+@C60 with crown ethers accelerates the intersystem crossing upon photoexcitation of the complex, thereby yielding 3(Li+@C60)*, when no charge separation by means of 1Li+@C60* occurs. Photoinduced charge separation by means of 3Li+@C60* with lifetimes of 135 and 120 μs for 1? Li+@C60 and 2? Li+@C60, respectively, and quantum yields of 0.82 in PhCN have been observed by utilizing time‐resolved transient absorption spectroscopy and then confirmed by electron paramagnetic resonance measurements at 4 K. The difference in crown ether structures affects the binding constant and the rates of photoinduced electron‐transfer events in the corresponding complex. 相似文献
214.
215.
Three magnetically recoverable Brønsted acidic calix[n]arene derivatives were successfully constructed by immobilizing calix[n]arene sulfonic acids onto silica-coated magnetic nanoparticles, a process, which allows calix[n]arene derivatives to acquire magnetic properties. All of the magnetically recoverable Brønsted acidic calix[n]arenes efficiently catalyze the coupling of electron-rich arenes with some alcohols in water. After separation and recovery from the reaction mixture by a simple magnet, these Brønsted acidic calix[n]arenes can be recycled many times without losing their catalytic activity. 相似文献
216.
pH effect on phosphate sorption by crystalline MnO(2) 总被引:1,自引:0,他引:1
The phosphate anions sorption on manganese dioxide was studied as a function of pH in the range 3-9 and at 293 K. The sorption was observed to increase with the increase in concentration of phosphate and decrease with the increase in pH. No effect of the phosphate adsorption upon the PZC of the solid suggested that the only outer sphere complexes were formed on the surface of the solid. The potentiometric titrations studies of the solid were also performed in the presence of different phosphate concentrations (0.53, 1.053, and 2.11 mmol L(-1)). The calculated pKa values showed that the solid protonation played a dominant role in the uptake of phosphate anions by the solid. 相似文献
217.
The dynamics of chemical reaction networks often takes place on widely differing time scales--from the order of nanoseconds to the order of several days. This is particularly true for gene regulatory networks, which are modeled by chemical kinetics. Multiple time scales in mathematical models often lead to serious computational difficulties, such as numerical stiffness in the case of differential equations or excessively redundant Monte Carlo simulations in the case of stochastic processes. We present a model reduction method for study of stochastic chemical kinetic systems that takes advantage of multiple time scales. The method applies to finite projections of the chemical master equation and allows for effective time scale separation of the system dynamics. We implement this method in a novel numerical algorithm that exploits the time scale separation to achieve model order reductions while enabling error checking and control. We illustrate the efficiency of our method in several examples motivated by recent developments in gene regulatory networks. 相似文献
218.
S. Talegaonkar G. Mustafa S. Akhter Z. I. Iqbal 《Journal of Dispersion Science and Technology》2013,34(5):690-701
The objective of the present investigation was to design a thermodynamically stable and dilutable nanoemulsion formulation of AT-Ca with minimum surfactant concentration that could improve its solubility as well as its oral bioavailability. The composition of optimized nanoemulsion formulation was Sefsol 218 and oleic acid (1:1) 10% w/w, as an oil phase, Tween-20 (19% w/w) as a surfactant, Carbitol (19% w/w) as a cosurfactant and distilled water (52% w/w) as an aqueous phase, containing 10 mg of AT. The optimized formulation showed higher% drug release (99.34%), lower droplet size (42.8 ± 0.42 nm) with low polydispersity index (0.237 ± 0.012), less viscosity (27.51 ± 1.01 cP) and infinite dilution capability. In vitro drug release from the nanoemulsion formulations was highly significant (p < 0.01) as compared to drug suspension. 相似文献
219.
Synthesis of two new p-tert-butylcalix[4]arene β-ketoimin derivatives for extraction of dichromate anion 总被引:1,自引:0,他引:1
Mevlut Bayrakci Seref Ertul Ozlem Sahin Mustafa Yilmaz 《Journal of inclusion phenomena and macrocyclic chemistry》2009,63(3-4):241-247
In this study the selective derivatization of p-tert-butylcalix[4]arene was carried out and two new p-tert-butylcalix[4]arene β-ketoimin, 5,11,17,23-tetra-tert-butyl-25,27-bis-3-methyl-[(β-ketoimine)-ethoxy]-26,28-dihydroxycalix[4]arene (4), and 5,11,17,23-tetra-tert-butyl-25,27-bis-3-chloro-[(β-ketoimine)-ethoxy]-26,28-dihydroxycalix[4]arene (5) have been synthesized. In the synthesis, the lower rim of p-tert-butylcalix[4]arene was modified in order to acquire binding site for the recognition of dichromate anion. It was observed that these ionophores 4 and 5 showed high affinity towards dichromate anion. The protonated Schiff-base forms of the receptors were effective for transferring the HCr2O7 ? anion from aqueous phase to a dichloromethane phase. 相似文献
220.
Ammar Mustafa N. M. Mikhailova N. S. Prostakov 《Chemistry of Heterocyclic Compounds》1996,32(1):65-67
9-Phenacylidene-4-azaf luorene and 9-bromo-9-(-bromophenacyl)-4-azafluorene have been used in the synthesis of spiro compounds with fragments of substituted pyrazolines. 1-Methyl-2-oxo-5 phenacylidene-indeno[2, 3-e]-1,2-dihydropyridine and hydrazine gave 1-methyl-2-oxo-3 phenylspiro[indeno(2, 3-e)-1,2-dihydropyridine-5,5-pyrazoline-2]. 相似文献