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121.
Teixeira RR Barbosa LC Maltha CR Rocha ME Bezerra DP Costa-Lotuf LV Pessoa C Moraes MO 《Molecules (Basel, Switzerland)》2007,12(5):1101-1116
3-Benzyl-furan-2(5H)-one (2a) and 3-(4-bromobenzyl)-furan-2(5H)-one (2b) were treated with TBDMSOTf and converted into the corresponding tert-butyldimethyl-silylfuran ethers. These furans were further condensed with several aromatic aldehydes affording compounds 5-14 with general 3-benzyl-5-arylidene-furan-2(5H)-one structures in 31% to 98% yields. Such compounds are analogues of the naturally occurring nostoclide lactones, reported to present moderate cytotoxic activity. Compounds 5-14 were submitted to an in vitro bioassay against the HL-60, HCT-8, SF295 and MDA-MB-435 cancer cell lines using the MTT cytotoxicity assay. 相似文献
122.
Gambi CM Giordano R Chittofrati A Pieri R Laurati M Baglioni P Teixeira J 《The journal of physical chemistry. B》2007,111(6):1348-1353
Aqueous mixed micellar solutions of perfluoropolyether carboxylic salts with ammonium counterions have been studied by small-angle neutron scattering. Two surfactants differing in the tail length were mixed in proportions n2/n3 = 60/40 w/w, where n2 and n3 are the surfactants with two and three perfluoroisopropoxy units in the tail, respectively. The tails are chlorine-terminated. The mixed micellar solutions, in the concentration range 0.1-0.2 M and thermal interval 20-40 degrees C, show structural characteristics of the interfacial shell that are very similar to ammonium n2 micellar solutions previously investigated; thus, the physics of the interfacial region is dominated by the polar head and counterion. The shape and dimensions of the micelles are influenced by the presence of the n3 surfactant, whose chain length in the micelle is 2 A longer than that of the n2 surfactant. The n3 surfactant favors the ellipsoidal shape in the concentration range 0.1-0.2 M with a 1/2 ionization degree of n2 micelles. The very low surface charge of the mixed micelles is attributed to the increase in hydrophobic interactions between the surfactant tails, due to the longer n3 surfactant molecules in micelles. The closer packing of the tails decreases the micellar curvature and the repulsions between the polar heads, by surface charge neutralization of counterions migrating from the Gouy-Chapman diffuse layer, leading to micellar growth in ellipsoids with greater axial ratios. 相似文献
123.
The present paper describes a procedure to isolate volatiles from rock-rose (Cistus ladanifer L.) using simultaneous distillation-extraction (SDE). High-value volatile compounds (HVVC) were selected and the influence of the extraction conditions investigated. The effect of the solvent nature and extraction time on SDE efficiency was studied. The best performance was achieved with pentane in 1 h operation. The extraction efficiencies ranged from 65% to 85% and the repeatability varied between 4% and 6% (as a CV%).The C. ladanifer SDE extracts were analysed by headspace solid phase microextraction (HS-SPME) followed by gas chromatography with flame ionization detection (GC-FID). The HS-SPME sampling conditions such as fiber coating, temperature, ionic strength and exposure time were optimized. The best results were achieved with an 85 μm polyacrylate fiber for a 60 min headspace extraction at 40 °C with 20% (w/v) of NaCl. For optimized conditions the recovery was in average higher than 90% for all compounds and the intermediate precision ranged from 4 to 9% (as CV %). The volatiles α-pinene (22.2 mg g−1 of extract), 2,2,6-trimethylcyclohexanone (6.1 mg g−1 of extract), borneol (3.0 mg g−1 of extract) and bornyl acetate (3.9 mg g−1 of extract) were identified in the SDE extracts obtained from the fresh plant material. 相似文献
124.
de Jesus Rodrigues Santos W Lima PR Tarley CR Kubota LT 《Analytical and bioanalytical chemistry》2007,389(6):1919-1929
Despite the increasing number of applications of molecularly imprinted polymers (MIP) in analytical chemistry, the synthesis
of polymers with hemin introduced as the catalytic center to mimic the active site of peroxidase remains as a challenge. In
the current work, a new type of molecularly imprinted polymer (MIP) was synthesized with 4-aminophenol (4-APh) as the template
and two monomers: hemin, which acts as the catalytic center, and methacrylic acid (MAA), which is used to build the active
sites. This work shows that MIP successfully mimics peroxidase. For this purpose, a flow injection analysis system coupled
to an amperometric detector was investigated through multivariate analysis. The determination of 4-APh was not affected by
the equimolar presence of structurally similar phenol compounds, including catechol, 4-chloro-3-methylphenol, 2-aminophenol,
guaiachol, chloroguaiachol and 2-cresol, thus highlighting the good performance of the imprinted polymer. Under the optimized
experimental conditions, an analytical curve covering a wide linear response range from 0.8 up to 500 μmol L−1 (r > 0.999) was obtained, and the method gave satisfactory precisions (n = 8), as evaluated via the relative standard deviation (RSD), of 4.1 and 3.2% for solutions of 4-APh of 50 and 500 μmol L−1, respectively. Recoveries of 96–111% from water samples (tap water and river water) spiked with 4-APh were achieved, thus
illustrating the accuracy of the proposed system.
Figure Schematic presentation of the synthesis of the MIP 相似文献
125.
de Almeida MV Teixeira FM de Souza MV Amarante GW Alves CC Cardoso SH Mattos AM Ferreira AP Teixeira HC 《Chemical & pharmaceutical bulletin》2007,55(2):223-226
Fourteen thalidomide analogs bearing two phthalimido units were prepared in high yields (83-94%) by condensation of different diamines with phthalic or 3-nitrophthalic anhydride. An in vitro investigation of the compounds as inhibitors of the TNF-alpha production was performed. The inhibition was higher for compounds bearing amino and nitro groups and was modulated by increasing the size of the spacers between the phthalimide groups. 相似文献
126.
Schrekker HS Gelesky MA Stracke MP Schrekker CM Machado G Teixeira SR Rubim JC Dupont J 《Journal of colloid and interface science》2007,316(1):189-195
A surface-enhanced Raman spectroscopy (SERS) study of imidazolium ionic liquid stabilized gold(0) nanoparticles (GNPs) furnished previously unknown knowledge about the coordination and stabilization mode of the imidazolium cation. GNPs were prepared by hydrazine reduction of a chloroauric acid solution in 1-triethylene glycol monomethyl ether-3-methylimidazolium methanesulfonate 2 as ether-functionalized room-temperature ionic liquid (RTIL). UV-vis spectroscopy showed the presence of GNP aggregates as absorptions extended to the NIR region. A parallel coordination mode for the imidazolium cation of RTIL 2 on the GNP surface was observed by SERS, which occurred without the simultaneous coordination of the 1-triethylene glycol monomethyl ether-functionality. Instead of this, the ether-functionality was directed away from the GNP surface and acted as steric barrier between the GNPs/GNP aggregates, thus preventing further aggregation. These new insights suggest that the imidazolium cation is responsible for electrosteric stabilization. 相似文献
127.
We have performed small angle neutron scattering experiments on the binary fluid mixture n-C6H14+n-C8F18 imbibed inside porous Vycor glass in the thermodynamic region corresponding to the bulk critical one. The resulting structure
can be represented as the sum of a temperature dependent Lorentzian term and a term describing the interference between the
porous matrix, a shell part richer in one component coating the glass surface, and a core part richer in the other component.
We observe critical fluctuations extending over distances markedly larger than the mean pore size.
Received 20 May 1999 相似文献
128.
129.
Arlindo Csar Matias Pereira Helison de Oliveira Carvalho Danna Emanuelle Santos Gonalves Karyny Roberta Tavares Picano Abraho Victor Tavares de Lima Teixeira dos Santos Heitor Ribeiro da Silva Francinaldo Sarges Braga Roberto Messias Bezerra Alessandro de Sousa Nunes Maira Tiyomi Sacata Tongo Nazima Júlia Gomes Cerqueira Talisson Taglialegna Janayra Maris Teixeira Jos Carlos Tavares Carvalho 《Molecules (Basel, Switzerland)》2021,26(16)
This study aimed to evaluate and compare the effects of co-treatment with purified annatto oil (PAO) or its granules (GRA, Chronic®) with that of testosterone on the orchiectomy-induced osteoporosis in Wistar rats. After surgery, rats were treated from day 7 until day 45 with testosterone only (TES, 7 mg/kg, IM) or TES + PAO or GRA (200 mg/kg, p.o.). The following parameters were evaluated: food/water intake, weight, HDL, LDL, glucose, triglycerides (TG), total cholesterol (TC), alkaline phosphatase levels, blood phosphorus and calcium contents, femur weight, structure (through scanning electron microscopy), and calcium content (through atomic absorption spectrophotometry). Our results show that orchiectomy could significantly change the blood lipid profile and decrease bone integrity parameters. Testosterone reposition alone could improve some endpoints, including LDL, TC, bone weight, and bone calcium concentration. However, other parameters were not significantly improved. Co-treatment with PAO or GRA improved the blood lipid profile and bone integrity more significantly and improved some endpoints not affected by testosterone reposition alone (such as TG levels and trabeculae sizes). The results suggest that co-treatment with annatto products improved the blood lipid profile and the anti-osteoporosis effects of testosterone. Overall, GRA had better results than PAO. 相似文献
130.
M. Teresa Duarte M. Ftima M. Piedade M. Paula Robalo Antnio P. S. Teixeira M. Helena Garcia 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(8):m386-m389
The title compound, (η5‐cyclopentadienyl)(4‐nitrobenzonitrile‐κN)(trimethylphosphine‐κP)(triphenylphosphite‐κP)iron(II) hexafluorophosphate, [Fe(C5H5)(C7H4N2O2)(C18H15O3P)(C3H9P)]PF6, has been characterized by spectroscopic and X‐ray diffraction in order to evaluate the tuning of the electron density at the metal centre and the extension of the π delocalization on the molecule due to the presence of phosphite and phosphine co‐ligands. The compound crystallizes in the centrosymmetric space group P21/c, which destroys the possibility of exhibiting any quadratic non‐linear optical properties. The packing shows a supramolecular zigzag chain of antiparallel cations connected via the PF6− anions through C—H⋯Fδ− interactions, with H⋯F distances ranging from 2.39 to 2.67 Å. Each zigzag chain is composed of isomeric organometallic fragments containing either R or S molecules. These chains are connected through weak intermolecular C—H⋯C interactions, forming a two‐dimensional plane parallel to (101). 相似文献