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991.
992.
Three methods have been examined for evaluating the concentration of nitrogen atoms in the afterglow of a nonequilibrium, helium-stabilized, atmospheric pressure plasma. These are nitric oxide titration, absolute emission intensity of N2(B 3g) and temporal decay of the N2(B 3g) emission. To employ the second method, the rate constants for the recombination of N atoms into N2(B 3g), at different vibrational levels of the B state, were determined. The third newly developed method has three advantages over the other two techniques: (1) it can predict the N-atom density for the entire afterglow, (2) it does not require calibration of the N2(B 3g) emission intensity, and (3) it does not disturb the gas flow. According to these measurements, the atmospheric pressure plasma produced a high density of nitrogen atoms, exceeding 4.0×1015 cm–3 at the edge of the discharge for 10 Torr N2 in 745 Torr He at 375 K and 15.5 W/cm3. 相似文献
993.
Orlik S. N. Pop G. Ganea R. Ostapyuk V. A. Alekseenko L. M. 《Theoretical and Experimental Chemistry》2004,40(3):187-191
We used X-ray phase analysis, IR, X-ray photoelectron, and NMR spectroscopy to characterize a synthesized mesoporous material (Fe,Al)-MCM-41. As a result of a certain combination of structural, acidic, and oxidation–reduction properties of the surface, (Fe,Al)-MCM-41 exhibits catalytic activity in reactions with participation of nitrogen oxides, in particular partial oxidation of propane by nitrogen(I) oxide to isopropanol. 相似文献
994.
《应用有机金属化学》2017,31(11)
Various nitrogen‐doped titania particles were prepared and, for visible light sensitizing, the biological pigment hematoporphyrin was grafted onto their surfaces. The nanohybrid products were characterized using X‐ray diffraction, Fourier transform infrared and ultraviolet–visible spectroscopies and Brunauer–Emmett–Teller surface area analysis. A high‐performance visible light helical flow photoreactor was designed and used for the photocatalytic degradation of methyl orange (MO) over these photocatalyst products. Accordingly, response surface methodology was employed for design of experiments and optimization. The influencing parameters were initial N/Ti molar ratio, dosage of nanohybrids and solution pH. These parameters were statistically significant and a quadratic correlation was developed for degradation efficiency (DE) variations. A maximum DE of 89.2% was attainable, after 60 min treatment, under the optimum conditions of initial N/Ti molar ratio of 4.93 (ca 5), nanohybrid dosage of 0.73 g l−1 and pH of 4.8. The MO degradation kinetics over the catalyst surface followed the modified Langmuir–Hinshelwood model. The important role of hydroxyl radicals was confirmed using mannitol scavenger. Performing the photocatalytic reaction with the developed set‐up showed excellent efficiency and energy consumption in comparison with similar processes. 相似文献
995.
One‐Step Synthetic Access to Isosteric and Potent Anticancer Nitrogen Heterocycles with the Benzo[c]phenanthridine Scaffold
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Tamara N. Steinhauer Dr. Ulrich Girreser Dr. Christopher Meier Prof. Dr. Mark Cushman Prof. Dr. Bernd Clement 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(24):8301-8308
A versatile one‐step two‐component cyclization to build new tetracyclic nitrogen heterocycles is described. Ortho‐methylhetarenecarbonitrile components were condensed with aldehydes to access a large library of differently substituted ring systems. The heterocyclic core can be easily modified by variation of the position of the endocyclic nitrogen atom in the o‐methylhetarenecarbonitrile substrate. The manner of the nucleophilic attack that leads to the condensation can be triggered by different electron‐density distribution in the molecule induced by the position of the nitrogen atom. Taking this into account, there is an electronic preference that leads to either pyridophenanthrolines or the corresponding pyridoazacarbazoles as the main products. We demonstrate the high antitumor potential of some of our synthesized heterocycles, which is strongly dependent on the substitution pattern introduced through the aldehyde component. The position and number of endocyclic nitrogen atoms play an important role regarding cytotoxicity of the studied compounds. 相似文献
996.
997.
998.
Ceric Ammonium Nitrate as the Novel Oxidizing Agent for the Facile Synthesis of (Dichloroiodo)arenes
Ceric ammonium nitrate (CAN) has been found to be a remarkable oxidizing agent for the oxidative conversion of iodoarenes to (dichloroiodo)arenes in acetic acid using aqueous HCl. The reaction of CAN with HCl generates in situ molecular chlorine, which is responsible for the oxidation. This method avoids the use of hazardous, toxic, and corrosive gaseous chlorine. 相似文献
999.
1000.
Ring Opening of Donor–Acceptor Cyclopropanes with the Azide Ion: A Tool for Construction of N‐Heterocycles
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Konstantin L. Ivanov Dr. Elena V. Villemson Dr. Ekaterina M. Budynina Dr. Olga A. Ivanova Dr. Igor V. Trushkov Prof. Mikhail Ya. Melnikov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):4975-4987
A general method for ring opening of various donor–acceptor cyclopropanes with the azide ion through an SN2‐like reaction has been developed. This highly regioselective and stereospecific process proceeds through nucleophilic attack on the more‐substituted C2 atom of a cyclopropane with complete inversion of configuration at this center. Results of DFT calculations support the SN2 mechanism and demonstrate good qualitative correlation between the relative experimental reactivity of cyclopropanes and the calculated energy barriers. The reaction provides a straightforward approach to a variety of polyfunctional azides in up to 91 % yield. The high synthetic utility of these azides and the possibilities of their involvement in diversity‐oriented synthesis were demonstrated by the developed multipath strategy of their transformations into five‐, six‐, and seven‐membered N‐heterocycles, as well as complex annulated compounds, including natural products and medicines such as (?)‐nicotine and atorvastatin. 相似文献