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901.
902.
Jandera P Cesla P Hájek T Vohralík G Vynuchalová K Fischer J 《Journal of chromatography. A》2008,1189(1-2):207-220
The overall peak capacity in comprehensive two-dimensional liquid chromatographic (LC x LC) separation can be considerably increased using efficient columns and carefully optimized mobile phases providing large differences in the retention mechanisms and separation selectivity between the first and the second dimension. Gradient-elution operation and fraction-transfer modulation by matching the retention and the elution strength of the mobile phases in the two dimensions are useful means to suppress the band broadening in the second dimension and to increase the number of sample compounds separated in LC x LC. Matching parallel gradients in the first and second dimension eliminate the necessity of second-dimension column re-equilibration after the independent gradient runs for each fraction, increase the use of the available second-dimension separation time and can significantly improve the regularity of the coverage of the available retention space in LC x LC separations, especially with the first- and second-dimension systems showing partial selectivity correlations. Systematic development of an LC x LC method with parallel two-dimensional gradients was applied for separation of phenolic acids and flavone compounds. Several types of bonded C18, amide, phenyl, pentafluorophenyl and poly(ethylene glycol) columns were compared using the linear free energy relationship method to find suitable column combination with low correlation of retention of representative standards. The phase systems were optimized step-by-step to find the mobile phases and gradients providing best separation selectivity for phenolic compounds. The optimization of simultaneous parallel gradients in the first and second dimension resulted in significant improvement in the utilization of the available two-dimensional retention space. 相似文献
903.
Budesínský M Sebestík J Bednarova L Baumruk V Safarík M Bour P 《The Journal of organic chemistry》2008,73(4):1481-1489
904.
Michaël Gras Bruno Therrien Georg Süss-Fink Petr Štěpnička Anna K. Renfrew Paul J. Dyson 《Journal of organometallic chemistry》2008,693(21-22):3419-3424
The cationic complexes [(η6-arene)Ru(SC5H4NH)3]2+, arene being C6H6 (1), MeC6H5 (2), p-iPrC6H4Me (3) or C6Me6 (4), have been synthesised from the reaction of 4-pyridinethiol with the corresponding precursor (η6-arene)2Ru2(μ2-Cl)2Cl2 and isolated as the chloride salts. The single-crystal X-ray structure of [4](PF6)2 reveals three 4-pyridinethiol moieties coordinated to the ruthenium centre through the sulphur atom, with the hydrogen atom transferred from the sulphur to the nitrogen atom. The electrochemical study of 1–4 shows a clear correlation between the Ru(II)/Ru(III) redox potentials and the number of alkyl substituents at the arene ligand (E°′ (RuII/III): 1 > 2 > 3 > 4), whereas the cytotoxicity towards A2780 ovarian cancer cells follows the series 4 > 1 > 3 > 2, the hexamethylbenzene derivative 4 being the most cytotoxic one. The corresponding reaction of the ortho-isomer, 2-pyridinethiol, with (η6-C6Me6)2Ru2(μ2-Cl)2Cl2 does not lead to the expected 2-pyridinethiolato analogue, but yields the neutral complex (η6-C6Me6)Ru(η2-SC5H4N)(η1-SC5H4N) (5). The analogous complex (η6-C6Me6)Ru(η2-SC9H6N)-(η1-SC9H6N) (6) is obtained from the similar reaction with 2-quinolinethiol. 相似文献
905.
Martin Lamač Josef Cvačka Petr Štěpnička 《Journal of organometallic chemistry》2008,693(21-22):3430-3434
Interaction of (Sp)-2-(diphenylphosphino)ferrocenecarboxylic acid [(Sp)-1] with N,N′-dicyclohexylcarbodiimide (DCC) and N-ethyl-N′-[3-(dimethylamino)propyl]carbodiimide (EDC) have been investigated in order to study the reacting system itself and to characterise side-products typically arising during the diimide-promoted condensation of acid (Sp)-1 with nucleophiles. The reaction between (Sp)-1 and DCC was found to give preferentially the respective urea derivative in the absence of a base, and (Sp)-2-(diphenylphosphino)ferrocenecarboxylic anhydride [(Sp,Sp)-3] when the same reaction was performed in the presence of 4-(dimethylamino)pyridine (DMAP). With EDC, the preference for a reaction pathway was less pronounced: whereas the reaction without the base afforded exclusively the corresponding urea, that in the presence of DMAP yielded a mixture of the urea and anhydride (Sp,Sp)-3. 相似文献
906.
907.
Petr Michalek Simona Dostalova Hana Buchtelova Natalia Cernei Ludmila Krejcova David Hynek Vedran Milosavljevic Ana Maria Jimenez Jimenez Pavel Kopel Zbynek Heger Vojtech Adam 《Electrophoresis》2016,37(14):2025-2035
Annual epidemics of influenza cause death of hundreds of thousands people and they also have a significant economic impact. Hence, a need for fast and cheap influenza diagnostic method is arising. The conventional methods for an isolation of the viruses are time‐consuming and require expensive instrumentation as well as trained personnel. In this study, we modified the surface of nanomaghemite (γ‐Fe2O3) paramagnetic core with tetraethyl orthosilicate and (3‐aminopropyl)triethoxysilane and the resulting particles were utilized for the isolation of H7N7 influenza virions. Consequently, we designed γ‐Fe2O3 paramagnetic core modified with calcium tripolyphosphate which was employed for the isolation of viral nucleic acid after virion's lysis. Both of these procedures can be performed rapidly in less than 10 min and, in combination with the RT‐PCR, the whole influenza detection can be shortened to few hours. Moreover, the whole protocol could be easily automated and/or miniaturized, and thus can serve as a basis for use in a lab‐on‐a‐chip device. We assume that magnetic isolation is an exceptional procedure which can significantly accelerate the diagnostic possibilities of a broad spectrum of diseases. 相似文献
908.
Kateřina Hrdá Jakub Opršal Petr Knotek Miloslav Pouzar Milan Vlček 《Chemical Papers》2016,70(11):1512-1520
Toxicity of zinc oxide nanoparticle (ZnO-NPs) powder and water soluble salt of Zn (ZnCl2) to the annelid Enchytraeus crypticus was tested in agarose gel. Influence of the spiking method on the resulting size of nanoparticles and on E. crypticus mortality was studied. Two methods of ZnO-NPs powder (mean particle size diameter of 10 nm) introduction into the exposure media were used. In the first method, the nano-powder was initially cryogenically ground with dry agar followed by an addition of water. The second procedure began with re-suspension of nanoparticles in demineralized water containing a dispersant (sodium pyrophosphate decahydrate). The obtained colloid was subsequently mixed with hot agar gel. Relative mortality in worms observed after 96 h of their exposure to the ZnO-NPs concentrations (all in mg of ZnO-NPs per kg of agar) of 50, 100, 200, 500 and 1000 in the cryogenically ground medium ranged between 28.9 % and 34.4 % and it did not exhibit any concentration dependence. When the second method of exposure media preparation was applied, the relative mortality ranged from 0 % to 66.6 % in the same concentration region depending on the concentration. Scanning electron microscopy (SEM) revealed the presence of large agglomerates (1–10 µm in diameter) in the media prepared by cryogenic grinding with the highest concentration of ZnO-NPs. Neither the cryogenically ground media with lower ZnO-NPs concentrations nor any media prepared from colloidal solutions contained agglomerates exceeding 100 nm, detectable by SEM. Hydrodynamic diameters of particles in the colloids used in the second method of agar preparation were measured using dynamic light scattering (DLS) and ranged between 164 nm and 240 nm. The observed toxicity was thus clearly dependent on the size of ZnO-NPs agglomerates and the technique of exposure media preparation. Experimentally detected LC50 value for dissolved Zn2+ was 37.2 mg kg?1 in agar. The same concentration of Zn induced an approximately 30 % mortality of E. crypticus when administered in form of cryogenically ground ZnO-NPs with agar. No observable effects were found at this ZnO-NPs concentration when the exposure medium was prepared from the colloid solution. 相似文献
909.
Ivana Šrámková Burkhard Horstkotte Hana Sklenářová Petr Solich Spas D. Kolev 《Analytica chimica acta》2016
A novel approach to the automation technique Lab-In-Syringe, also known as In-Syringe Analysis, is proposed which utilizes a secondary inlet into the syringe void, used as a size-adaptable reaction chamber, via a channel passing through the syringe piston. This innovative approach allows straightforward automation of head-space single-drop microextraction, involving accurately controlled drop formation and handling, and the possibility of on-drop analyte quantification. 相似文献
910.
The Synthesis and Biological Evaluation of N‐Substituted 1H‐Benzimidazol‐2‐yl‐1H‐pyrazole‐3,5‐diamines
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The synthesis of 1H‐benzimidazol‐2‐yl‐1H‐pyrazole‐3,5‐diamines has been developed. Synthesized bisheteroaryls contain two privileged medicinal scaffolds, aminopyrazole and benzimidazole, with two diversity positions at N1 of benzimidazole and C3 of pyrazole, respectively. The three‐step synthesis includes the Mitsunobu N‐alkylation of benzimidazole and subsequent one‐pot formation of aminopyrazole involving substitution of methylthio groups with amine and hydrazine followed with final ring closure. Inhibitory activity toward cyclin‐dependent kinase 2/cyclin E and cytotoxicity against two cancer cell lines were evaluated for all novel pyrazoles. Two compounds showed modest cyclin‐dependent kinase inhibition activity and cytotoxicity against cancer cell lines K562 and MCF7. 相似文献