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961.
Cis-Cyclopropanediamine 4 is a very important component of compounds possesing anticancer activity (1). It was also used as a starting material for the synthesis of variety compounds on which the complexing abilities (2) and the Hetero-Cope-Rearrangement (3, 4) were studied. 相似文献
962.
Jakub Herman Jerzy Dziaduszek Roman Dąbrowski Jerzy Kędzierski Krystian Kowiorski Venkata Sai Dasari 《Liquid crystals》2013,40(9):1174-1182
We report the synthesis of new laterally alkyl substituted high birefringent quaterphenyl and phenylethynyltolane liquid crystals with isothiocyanate terminal group. The thermal and optical properties such as birefringence are measured and discussed based on their molecular structures. The compounds exhibit birefringence (Δn) in the range of 0.44–0.63, and are expected to be appropriate components of high birefringent nematic mixtures for various applications. 相似文献
963.
Ravindra Dhar Avneesh Mishra Abhay S. Pandey Magdalena Zurowska Roman S. Dabrowski 《Liquid crystals》2013,40(11):1466-1476
Frequency- and temperature-dependent dielectric and switching parameters of a room temperature tri-component antiferroelectric liquid crystal mixture W-287 have been determined. Dielectric, optical texture and thermodynamic studies show wide room temperature range antiferroelectric SmC*a (?91.1°C to <–25°C) phase in addition to high temperature paraelectric SmA* (?2.6°C) and ferroelectric SmC* (?4.4°C) phases. The dielectric studies carried out in the frequency range of 1–35 MHz under planar anchoring condition of the molecules show five different relaxation modes appearing in the SmA*, SmC* and SmC*a phases. Using Curie–Weiss law fit, ferroelectric SmC* to paraelectric SmA* transition temperature has been found to be 91.8°C. The dielectric response of SmC*a phase exhibits unusually three relaxation modes due to collective as well as individual molecular processes in addition to phason mode in the SmC* phase and amplitudon mode in the SmA* phase. Spontaneous polarisation, switching time and rotational viscosity have also been determined. The maximum value of PS is ?300 nC/cm2, whereas viscosity is moderate. Switching time is of the order of few milli seconds. 相似文献
964.
Addition of 1,2-O-(ethane-1,2-diyl)-α-d-glucofuranose, which is originally a poor organogelator, can support the gelating abilities of good glucofuranose-based organogelators. The properties of such two-component gels can be tuned by changing the proportion of the saccharides. The saccharide's ability to form two-component gels can be explained on the basis of its crystal structure, particularly, the way in which sugar molecules stack (or not) into hydrogen bond-based chains and the architecture of these chains. The thermal stability of the obtained two-component gels was characterised by measuring its T gel temperature. SEM and XRD techniques were used to characterise the xerogels. Addition of poor gelator increases the thermal stability of the gel formed by good gelator 相似文献
965.
Ariel Adamski Andrzej Bogucki Roman Świetlik Rafał J. Wróbel Łukasz Klapiszewski Teofil Jesionowski 《Supramolecular chemistry》2013,25(9):571-583
An effective method for the synthesis of novel adenine amides was developed and successfully implemented, leading to 4-propyloxy-N-(9H-purin-6-yl)benzamide (1) and 4-dodecyloxy-N-(9H-purin-6-yl)benzamide (2). The compounds were fully characterised by means of spectroscopic (1H NMR, 13C NMR, FT-IR) and thermal (TG, DSC) analysis. The crystallographic analysis revealed that the formation of supramolecular chains relies on hydrogen bonding between amide functionalities. All supramolecular synthons found in the crystal structure of 1 were confirmed with the temperature-dependent IR method. The temperature-dependent IR method is useful in determining supramolecular interactions for compound 2, for which the crystal structure could not be obtained. A detailed analysis of temperature-dependent FT-IR spectra was used for the first time to identify the hydrogen bonds that exist in the solid state of our compounds; it can therefore be considered a promising method for the pattern recognition of hydrogen bonding in supramolecular chemistry. 相似文献
966.
Roman Mazurkiewicz Beata Fryczkowska Rafał Gabański Roman Luboradzki Andrzej Włochowicz Wojciech Mól 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2589-2598
A reaction of g -carbonyl phosphorus ylides with imidoyl halides gives hitherto unknown g -( N -acylamino)vinylphosphonium salts. The same product can be obtained using the N-monosubtituted amide/Ph 3 PBr 2 /Et 3 N system instead of imidoyl halide. The key step of the reaction probably involves an intramolecular [1,3] O-to-N migration of the vinyl group, converting the primary O -imidoylation product into g -( N -acylamino)vinylphosphonium salt. 相似文献
967.
Roman Dembinski Ewa Krawczyk Aleksandra Skowronska 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):345-348
Abstract A novel efficient synthesis of sym-monoselenopyrophosphates 3 based on the reaction of diphosphoryl diselenides 1 with dialkyltrimethylsilyl phosphites 2 is described. 相似文献
968.
A modified peak-deconvolution procedure for complex crystallization processes was introduced. The method is based on the constrained curve-fitting technique using the Fraser–Suzuki (FS) function, where the FS asymmetry parameter a 3 correlates with the value of the Johnson–Mehl–Avrami (JMA) kinetic parameter m. The correlation was verified for an extensive number of theoretically simulated JMA curves; in addition, the dependencies of the a 3 parameter on other kinetic variables (E, A, q +) were quantified. The suggested deconvolution procedure was tested on two glassy systems with different overlay degree of the involved overlapping surface and bulk crystallization processes. In both cases, the kinetic analysis of deconvoluted data provided reasonable, consistent and accurate results. However, certain level of knowledge and experience was needed in order to correctly recognize and consequently account for all deviations from the theoretical behavior caused by thermal gradients or imperfections of the data acquisition process. As the input data for the fitting procedure can be in any form equivalent to the dα/dT temperature dependence, the method seems to be highly universal and may be applied to data obtained by various TA techniques. 相似文献
969.
Dr. Julien Lieffrig Dr. Olivier Jeannin Arkadiusz Frąckowiak Dr. Iwona Olejniczak Roman Świetlik Dr. Slimane Dahaoui Dr. Emmanuel Aubert Prof. Dr. Enrique Espinosa Dr. Pascale Auban‐Senzier Dr. Marc Fourmigué 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):14804-14813
Charge‐assisted halogen bonding is unambiguously revealed from structural and electronic investigations of a series of isostructural charge‐transfer complexes derived from iodinated tetrathiafulvalene and tetracyanoquinodimethane derivatives, (EDT‐TTFI2)2(TCNQFn), n=0–2, which exhibit variable degrees of ionicity. The iodinated tetrathiafulvalene derivative, EDT‐TTFI2, associates with tetracyanoquinodimethane (TCNQ) and its derivatives of increasing reduction potential (TCNQF, TCNQF2) through highly directional C? I???N≡C halogen‐bond interactions. With the less oxidizing TCNQ acceptor, a neutral and insulating charge‐transfer complex is isolated whereas with the more oxidizing TCNQF2 acceptor, an ionic, highly conducting charge‐transfer salt is found, both of 2:1 stoichiometry and isostructural with the intermediate TCNQF complex, in which a neutral–ionic conversion takes place upon cooling. A correlation between the degree of charge transfer and the C? I???N≡C halogen‐bond strength is established from the comparison of the structures of the three isostructural complexes at temperatures from 300 to 20 K, thus demonstrating the importance of electrostatics in the halogen‐bonding interaction. The neutral–ionic conversion in (EDT‐TTFI2)2(TCNQF) is further investigated through the temperature dependence of its magnetic susceptibility and the stretching modes of the C≡N groups. 相似文献
970.
Jaroslav Melar Vratislav Bednarik Roman Slavik Miroslav Pastorek 《Central European Journal of Chemistry》2013,11(5):782-789
The effect of hydrothermal treatment on the structure of an aluminosilicate polymer prepared by a polycondensation reaction between silicate and hydroxoaluminate in alkaline aqueous solution was studied. The structural changes were investigated using X-ray diffraction analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy imaging and thermogravimetric analysis. The results indicated that the amorphous aluminosilicate polymer transformed into a crystalline product during the hydrothermal treatment at 145°C. The crystalline phase was identified as a mineral of the zeolite group, most likely phillipsite. This transformation required an alkaline environment during the hydrothermal treatment. 相似文献