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981.
982.
The aim of this work is to investigate the possibility of using industrial wastes as new grinding aids in cement industry. Two samples of Soapstock from different oils were used (Sunflower Oil (SO), Corn Oil (CO)). For this purpose, one reference sample was produced without using any admixture and another one using reference grinding aids (Triethanolamine TEA).The raw mixes were characterized via differential scanning calorimetry (DSC), FT-IR technique, chemical analysis by X-ray florecence (XRF), X-ray powder diffraction (XRD), and mineral composition by Bouge equation and determination of free calcium oxide (CaOf) for clinker. Grindability was determined according to PSD and resides on sieve 90 μm.In all cases the addition of grinding aids resulted in the improvement of grindability (fact that was attributed to the additive ability not only to reduce resistance to combination, but also to prevent agglomeration and powder coatings of ball and mill), and the clinker produced by this admixture was not effective. 相似文献
983.
Ziad Omran Chris P. Guise Linwei Chen Cyril Rauch Ashraf N. Abdalla Omeima Abdullah Ikhlas A. Sindi Peter M. Fischer Jeff B. Smaill Adam V. Patterson Yuxiu Liu Qingmin Wang 《Molecules (Basel, Switzerland)》2021,26(11)
Phenanthroindolizidines, such as antofine and tylophorine, are a family of natural alkaloids isolated from different species of Asclepiadaceas. They are characterized by interesting biological activities, such as pronounced cytotoxicity against different human cancerous cell lines, including multidrug-resistant examples. Nonetheless, these derivatives are associated with severe neurotoxicity and loss of in vivo activity due to the highly lipophilic nature of the alkaloids. Here, we describe the development of highly polar prodrugs of antofine and tylophorine as hypoxia-targeted prodrugs. The developed quaternary ammonium salts of phenanthroindolizidines showed high chemical and metabolic stability and are predicted to have no penetration through the blood–brain barrier. The designed prodrugs displayed decreased cytotoxicity when tested under normoxic conditions. However, their cytotoxic activity considerably increased when tested under hypoxic conditions. 相似文献
984.
Kazuki Fukushima Daniel J. Coady Gavin O. Jones Hamid A. Almegren Abdullah M. Alabdulrahman Fares D. Alsewailem Hans W. Horn Julia E. Rice James L. Hedrick 《Journal of polymer science. Part A, Polymer chemistry》2013,51(7):1606-1611
This article describes studies on the catalytic activity of several nitrogen‐based organic catalysts for the depolymerization of poly(ethylene terephthalate) (PET), in which a few cyclic amidines work more effectively than a potent, bifunctional guanidine‐based catalyst 1,5,7‐triazabicyclo‐[4,4,0]‐dec‐5‐ene (TBD) in the presence of short chain diols that play a role in activation of carbonyl groups through hydrogen bonding. Further studies prove that the catalytic efficiency at the above specific conditions depends only on the extent of activation of a hydroxyl group rather than simply the pKa of the bases. For glycolysis with excess short‐chain alkanediols, 1,8‐diazabicyclo[5.4.0]undec‐7‐ene is the best catalyst. In contrast, TBD shows outstanding catalytic activity in depolymerizations of PET with mono‐alcohols and longer‐chain diols. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
985.
Let p(z) be a polynomial of degree n and for any real or complex number α, let Dαp(z)=np(z)+(α−z)p′(z) denote the polar derivative of the polynomial p(z) with respect to α. In this paper, we obtain inequalities for the polar derivative of a polynomial having all its zeros inside or outside a circle. Our results shall generalize and sharpen some well-known polynomial inequalities. 相似文献
986.
Khalid S. Khairou Mohamed A. Abdullah Kamal I. Aly Nariman M. Nahas Ameena M. Al-Bonian 《Arabian Journal of Chemistry》2009,2(1):65-71
A new category of poly(ester-amide)s based on diarylidenecyclohexanone in the main chain were synthesized via interfacial polycondensation of two monomers namely: 2,6-bis(4-hydroxybenzylidene) cyclohexanone I and 2,6-bis(4-hydroxy-3-methoxybenzylidene) cyclohexanone II with diacid chlorides IIIa–c. The model compounds were synthesized by reacting one mole of compounds IVa–c with two monomers I and II. The structure of the model compounds was confirmed by correct elemental and spectral analyses. The various characteristics of the resulting polymers including: solubility, viscosity, thermal analysis, and X-ray diffraction analysis were determined and discussed. The majority of the polymers were insoluble in most common organic solvents. The viscosity measurements in dimethylsulfoxide showed the values 0.58–0.79 dl/g. Thermal analysis showed that they were thermally stable up to 500 °C. X-ray analysis showed that the polymers had some degree of crystallinity in the region 2θ = 5–50°. 相似文献
987.
Ayyad SE Al-Footy KO Alarif WM Sobahi TR Bassaif SA Makki MS Asiri AM Al Halwani AY Al Halawani AY Badria AF Badria FA 《Chemical & pharmaceutical bulletin》2011,59(10):1294-1298
The petroleum ether extract of the red alga Laurencia obtusa afforded three new C(15) acetogenins (cyclic ether enyne): (12Z)-cis-maneonene-D (1), (12E)-cis-maneonene-E (2), and (12Z)-trans-maneonene-C (3), along with one known cis-maneonene-A (4). Blood neutrophils were prepared, cultured, and incubated for 24, 48, and 72 h in medium with and without isolated compounds. Blood neutrophils were prepared, cultured, and incubated for 24, 48 and 72 h in medium with and without the isolated compounds. Both morphology and DNA fragmentation methods assessed the percentage of neutrophils apoptosis in each culture. In the present study, several observations have been made concerning the apoptosis-inducing or inhibiting effect of 1 and 2. Both compounds had no inhibition of apoptosis but apoptosis was enhanced significantly by aging. However, 1 stimulated apoptosis of normal only at the initial 24 h. After that there was no significant difference in apoptosis with or without compound 1, while 2 stimulated apoptosis at all the times. The apoptosis induced by these two compounds was demonstrated by DNA fragmentation assay and microscopic observation. These observations suggest that compounds 1 and 2 may be involved in regulation of programmed death in the initiation and propagation of inflammatory responses. 相似文献
988.
Afzan A Abdullah NR Halim SZ Rashid BA Semail RH Abdullah N Jantan I Muhammad H Ismail Z 《Molecules (Basel, Switzerland)》2012,17(4):4326-4342
Carica papaya L. leaves have been used in ethnomedicine for the treatment of fevers and cancers. Despite its benefits, very few studies on their potential toxicity have been described. The aim of the present study was to characterize the chemical composition of the leaf extract from 'Sekaki' C. papaya cultivar by UPLC-TripleTOF-ESI-MS and to investigate the sub-acute oral toxicity in Sprague Dawley rats at doses of 0.01, 0.14 and 2 g/kg by examining the general behavior, clinical signs, hematological parameters, serum biochemistry and histopathology changes. A total of twelve compounds consisting of one piperidine alkaloid, two organic acids, six malic acid derivatives, and four flavonol glycosides were characterized or tentatively identified in the C. papaya leaf extract. In the sub-acute study, the C. papaya extract did not cause mortality nor were treatment-related changes in body weight, food intake, water level, and hematological parameters observed between treatment and control groups. Some biochemical parameters such as the total protein, HDL-cholesterol, AST, ALT and ALP were elevated in a non-dose dependent manner. Histopathological examination of all organs including liver did not reveal morphological alteration. Other parameters showed non-significant differences between treatment and control groups. The present results suggest that C. papaya leaf extract at a dose up to fourteen times the levels employed in practical use in traditional medicine in Malaysia could be considered safe as a medicinal agent. 相似文献
989.
Jun Ma Xuelan Zhang Ning Zhao Abdullah S.N. Al-Arifi Taieb Aouak Zeid Abdullah Al-Othman Fukui Xiao Wei Wei Yuhan Sun 《Journal of molecular catalysis. A, Chemical》2010,315(1):76-81
The mechanisms for the reaction of propylene glycol (PG) with CO2 catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) were theoretically investigated by density functional theory (DFT) method at the B3LYP/6-311++G(d,p) level. Through analyzing the optimized structures and energy profiles along the reaction paths, the PG-activated route was identified as the most probable reaction path, in which the rate-determining step was the nucleophilic attack of one of the O atoms in CO2 on the hydroxyl linked C atom in PG with energy barrier 56.96 kcal/mol. The catalytic role of TBD could be considered as a proton bridge activated by the synergistic action of its N atoms. 相似文献
990.
Abdullah Aydın Mehmet Akkurt Leyla Uzun Leyla Yıldırım Tijen Önkol 《Journal of chemical crystallography》2010,40(10):816-820