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351.
Kazi TG Baig JA Shah AQ Kandhro GA Khan S Afridi HI Kolachi NF Wadhwa SK Shah F Baig AM 《Journal of AOAC International》2011,94(1):293-299
A simple and rapid cloud point extraction (CPE) procedure was applied for preconcentration of trace quantities of arsenic (As) in scalp hair samples. The samples were subjected to microwave-assisted digestion in a mixture of nitric acid and hydrogen peroxide (2 + 1, v/v) prior to preconcentration by CPE. The As in digested samples was complexed with ammonium pyrrolidine dithiocarbamate (APDC), and the resultant As-PDC complex was extracted by a nonionic surfactant, octylphenoxypolyethoxyethanol (Triton X-114). After centrifugation, the surfactant-rich phase was diluted with 0.1 M HNO3 in methanol and analyzed by electrothermal atomic absorption spectrometry. The experimental parameters, i.e., amount of APDC, concentration of Triton X-114, equilibrium temperature and time, were optimized. For validation of the proposed method, a certified reference material (CRM) of human hair (BCR 397) was used. No significant difference (P > 0.05) was observed between the experimental results and certified values of the CRM (paired t-test). The LOD and LOQ obtained under the optimal conditions were 0.025 and 0.083 microg/kg, respectively. The developed method was applied for the determination of As in scalp hair samples from male and female subjects of two villages of Khairpur Mir's, Pakistan. 相似文献
352.
Fatima Al‐Omran Abdel‐Zaher A. Elassar Adel Abou El‐Khair 《Journal of heterocyclic chemistry》2003,40(2):249-254
New synthetic routes for triazolopyridine, pyridopyrimidine, pyridotriazine, imidazopyridine and pyri‐dazine derivatives incorporating a coumarin moiety with interesting biological activities are reported. Reactions of the 2‐oxo‐4‐(2‐dimethylaminoethenyl)‐2H‐chromene‐3‐carbonitrile ( 4 ) and 2‐amino‐4‐(2‐dimethylaminoethenyl)quinoline‐3‐carbonitrile ( 5 ) with benzotriazol‐1‐yl‐acetic acid hydrazide ( 6 ) affords the substituted [1,2,4]triazolo[1,5‐a]pyrido[3,4‐c]coumarines 9 and quinoline 12 , respectively. Treatment of 4 with 2‐amino‐pyridine, glycine, urea, 3‐aminocrotononitrile or cyanothioacetamide affords 14–18 , respectively. Treatment of 3‐amino‐3,4‐dihydro‐4‐imino‐chromeno[3,4‐c]pyridin‐5‐one (10) with α‐chloro‐acetylacetone affords pyridotriazine derivative 21 . Compound 4 was also coupled with benzenediazonium chloride to afford 2‐oxo‐4‐[2‐oxo‐1‐(phenyl‐hydrazono)‐ethyl]‐2H‐chromene‐3‐carbonitrile 25 . Treatment of the latter product with malononitrile afforded the 1‐phenyl‐3‐(3′‐Cyano‐2′‐oxo‐coumarin‐4′‐yl)‐6‐oxo‐pyridazine‐5‐carbonitrile ( 27 ). The structures of the newly synthesized compounds have been established on the basis of analytical and spectral data. 相似文献
353.
Saman Fatima Sarwar Beg Mohammed Samim Farhan J. Ahmad 《Journal of separation science》2019,42(21):3293-3301
A systematic Quality by Design approach was employed for developing an isocratic reversed‐phase liquid chromatographic technique for the estimation of ropinirole hydrochloride in bulk drug and pharmaceutical formulations. LiChrospher RP 18‐5 Endcapped column (25 cm × 4.6 mm id) at ambient temperature (25 ± 2°C) was used for the chromatographic separation of the drug. The screening of factors influencing chromatographic separation of the active pharmaceutical ingredient was performed employing fractional factorial design to identify the influential factors. Optimization of the selected factors was carried out using central composite design for selecting the optimum chomatographic conditions. The mobile phase employed was constituted of Solvent A/Solvent B (65:35 v/v) (Solvent A [methanol/0.05 M ammonium acetate buffer, pH 7, 80:20 v/v] and Solvent B [high performance liquid chromatography grade water]) and used at 0.6 mL/min flow rate, while UV detection was performed at 250 nm. Linearity was achieved in the drug concentration range 5–100 µg/mL (R2 = 0.9998) with limits of detection and quantification of 1.02 and 3.09 µg/mL, respectively. Method validation was performed as per ICH guidelines followed by forced degradation studies, which indicated good specificity of the developed method for detecting ropinirole hydrochloride and its possible degradation products in the bulk drug and pharmaceutical formulations. 相似文献
354.
355.
Malika Elouali Christophe Beyens Fatima Zohra Elouali Oleg Yaroshchuk Boucif Abbar Ulrich Maschke 《Macromolecular Symposia》2011,303(1):108-113
Summary: Electro-optical properties of Polymer Dispersed Liquid Crystal (PDLC) films doped with different nanoparticles (NPs), as well as optical and morphological properties of liquid crystal/NP mixtures have been investigated. PDLC films were prepared by UV irradiation of thiol-ene monomers and liquid crystal E7 in the presence of a small amount (0.5 and 1 wt.%) of nanoparticles. The presence of NP strongly influence the properties of liquid crystal/NP mixtures. In particular, adding nanoparticles results in a decrease of the glass and nematic-isotropic transition temperatures of the LC, suggesting that strong interactions occur between LC and nanoparticles. 相似文献
356.
Coagulansins A ( 1 ) and B ( 2 ), two new withanolides, were isolated from the CHCl3‐soluble fraction of Withania coagulans Dunal , along with two known withanolides, coagulin R and withanolide P. Their structures were assigned by means of 1H‐ and 13C‐NMR spectra, DEPT, and 1H,1H‐COSY, NOESY, HMQC, and HMBC experiments. 相似文献
357.
El Fallah MS Badyine F Vicente R Escuer A Solans X Font-Bardia M 《Dalton transactions (Cambridge, England : 2003)》2006,(24):2934-2942
The syntheses, structural characterization and magnetic behavior of five new copper(II) polynuclear compounds with formulae [Cu4(mu2-CH3COO)2(mu-bdmap)2(micro(1,5)-dca)2(dca)2(H2O)2] 1, [Cu2(mu2-CH3COO)(mu-bdap)(mu(1,1,5)-dca)(mu(1,3)-dca)]n 2, [Cu4(mu2-CH3COO)2(mu-bdmap)2(mu(1,1)-NCS)2(NCS)2] 3, [Cu2(mu2-CH3COO)(mu-bdap)(NCS)2] 4 and [Cu2(mu(1,3)-N3)(mu-bdmap)(N3)2]n 5 in which bdmapH is 1,3-bis(dimethylamino)-2-propanol, bdapH is 1,3-bis(amino)-2-propanol and dca is the anionic dicyanamide ligand, are reported herein. Tetranuclear complex 1 crystallizes in the monoclinic system, space group P2(1)/n, with unit cell parameters a = 8.284(8), b = 21.52(1), c = 11.432(3) A, beta = 105.19(2) degrees , Z = 2. Bi-dimensional complex 2 crystallizes in the triclinic system, space group P1, with unit cell parameters a = 8.184(5), b = 8.792(2), c = 10.887(2) A, alpha = 75.65(2), beta = 76.55(3), gamma = 74.36(3) degrees , Z = 2. Tetranuclear complex 3 crystallizes in the triclinic system, space group P1, with unit cell parameters a = 8.455(4), b = 9.114(9), c = 12.744(8) A, alpha = 104.62(8), beta = 99.86(6), gamma = 106.10(8) degrees, Z = 1. Dinuclear complex 4 crystallizes in the triclinic system, space group P1, with unit cell parameters a = 8.15(1), b = 8.18(2), c = 11.44(1) A, alpha = 69.39(2), beta = 80.36(2), gamma = 80.37(2) degrees , Z = 2. One-dimensional complex 5 crystallizes in the orthorhombic system, space group P2(1)2(1)2(1), with unit cell parameters a = 20.45(4), b = 11.36(3), c = 6.43(1) A, Z = 4. The magnetic behavior of all the complexes has been checked giving a bulk antiferromagnetic coupling in all the cases with |J| values in the range 109-144 cm(-1) for 1-4. Compound 5 is diamagnetic in the 2-300 K range of temperatures. The found J values 1-5 for can be justified from the structural data taking into account the orbital countercomplementarity for 1-4 and the orbital complementarity for 5. 相似文献
358.
Abdulrahman Alsayari Abdullatif Bin Muhsinah Yahya I. Asiri Mohammad Y. Alfaifi Serag Eldin I. Elbehairi Fatima Alatibi Nahed Nasser E. El-Sayed Yahia N. Mabkhot 《Journal of heterocyclic chemistry》2020,57(7):2911-2922
5-(2-Bromoacetyl)-2,3,4-trisubstituted-thiophene was used as a synthetic intermediate to prepare a series of thiophene derivatives and thiophene incorporating oxazole, imidazole, thiazole, pyrrole, and pyridine rings via substitution and cyclo-condensation reactions. The data were extracted from the spectra of the resulting products confirmed their suggested structures. The newly synthesized compounds were screened to evaluate their in vitro antimicrobial activity vs several positive and negative gram bacteria and fungi. The screening data revealed that the thiophene derivative 7a , incorporating a thiazole ring, displayed strong activity against all tested microorganisms when compared with the antibiotics used. 相似文献
359.
Shehadi Ihsan Abla Fatima Wakefield Bryan Reibenspies Joseph Arooj Mahreen Mohamed Ahmed A. 《Research on Chemical Intermediates》2020,46(1):593-607
Research on Chemical Intermediates - Chemical transformations such as nitrile hydration or carbon–oxygen bond formation reactions under gentle conditions are important in the pharmaceutical... 相似文献
360.
Farré M Martínez E Hernando MD Fernández-Alba A Fritz J Unruh E Mihail O Sakkas V Morbey A Albanis T Brito F Hansen PD Barceló D 《Talanta》2006,69(2):323-333
An inter-laboratory comparison exercise was conducted under the European Union funded project entitled: Screening Methods for Water Data Information in Support of the Implementation of the Water Framework Directive (SWIFT-WFD) and coordinated by the Consejo Superior de Investigaciones Científicas (CSIC), in order to evaluate the reproducibility of different toxicity tests based on the bioluminescence inhibition of Vibrio fischeri, for the rapid water toxicity assessment.For the first time, this type of exercise has been organized in Europe, and using different tests based on the same principle. In this exercise, 10 laboratories from 8 countries (Austria, Cyprus, Germany, Greece, Italy, Portugal, Romania, and Spain) took place, and a total number of 360 samples were distributed.During the exercise, six series of six samples were analyzed along 5 months. Every batch of samples was composed by three real samples and three standard solutions. The real samples were: a raw influent and the effluent of a wastewater treatment plant (WWTP), and a sample from a first settlement of the WWTP spiked with a mixture of toxicant standards.A final number of 330 (91.7%) samples was analyzed, 3300 values in duplicate were collected, and the results for each sample were expressed as the 50% effective concentration (EC50) values calculated through five points of dilution inhibition curves, after 5 and 15 min of incubation times.A statistical study was initiated using 660 results. The mean values, standard deviations (σ), variances (σ2), and upper and lower warning limits (UWL and LWL) were obtained, using the EC50 values calculated with the result from the participating laboratories.The main objectives of this toxicity ring study were to evaluate the repeatability (r) and reproducibility (R) when different laboratories conduct the test, the influence of complex matrix samples, the variability between different tests based on the same principle, and to determine the rate at which participating laboratories successfully completed tests initiated.In this exercise, the 3.93% toxicity values were outliers according with the Z-score values and the Dixon test. The samples with the greater number of outliers were those with the smallest variability coefficient, corresponding to the greater and the smaller toxicity level.No relation was found through the cluster analysis, between the final results and the different commercial devices involved. Testing by multiple commercial devices did not appear to reduce the precision of the results, and the variability coefficient for the exercise was nearby to the average value for past editions carried out at national level, where the different participants used the same commercial device.Stability of samples was also followed during the exercise. While statistical significance differences were not found for the greater part of samples, for the sample from the WWTP influent, a significant decrease of the toxicity value was found along this study. Nevertheless, this was a type of sample with a high toxicity level during all the exercise.On the other hand, in order to obtain the chemical characterization of real samples, those were analyzed by chromatographic techniques, using different sequential solid phase extraction (SSPE) procedures, followed by liquid chromatography coupled with mass spectrometry (LC-MS), and gas chromatography-mass spectrometry (GC-MS). Good agreement was found between the chemical analysis results and the toxicity level of the samples. 相似文献