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61.
K. S. Kumar K. Suvardhan D. Rekha L. Krishnaiah P. Chiranjeevi 《Journal of Analytical Chemistry》2006,61(6):560-565
Facile and sensitive spectrophotometric methods were developed for the determination of carbofuran in its formulations and
environmental samples by using new reagents. The methods were based on the coupling reaction of hydrolysed product of cabofuran
with diazotized reagents, namely, 2,6-dibromo-4-methylaniline, 2,6-dibromo-4-nitroaniline, and 2,4,6-tribromoaniline in basic
medium to give color derivatives having the absorption maximum at 468, 474, and 410 nm, respectively. The color derivatives
were correspondingly stable for 40, 30, and 16 h. Beer’s law was obeyed in the carbofuran concentration range 0.2–10.0 μg/mL.
The proposed methods have been found to be applicable to the determination of carbofuran in its formulations, tap and distilled
water, grains, polluted water, plant material (cabbage), and soil samples.
The text was submitted by the authors in English. 相似文献
62.
The incorporation of (±)-norcoclaurine, (±)-coclaurine, (±)-N-methylcoclairine, (±)-N-methylnorcoclaurine into nornuciferine-I in Croton sparsiflorus morong has been studied, and the specific utilization of the (±)-N-methylcoclaurine demonstrated. The evidence supports the direct oxidative coupling of (+)-(S)-N-methylcoclaurine to give N-methylcrotsparine, which in turn is shown to be a specific precursor of nornuciferine-I. The experiments also show that N-methylcrotsparine is reduced to N-methylcrotsparinol and it is N-methylcrotsparinol-I which is preferentially dehydrated and rearranged to nornuciferine-I. 相似文献
63.
We report side chain urethane–methacrylate comb polymers based on the renewable resource cardanol and its saturated analogue 3‐pentadecyl phenol and their self‐assembly into pores, spheres, vesicles, tubes, and so forth. The monomers were synthesized in one pot by coupling 1 equiv. of isophorone diisocyanate with 1 equiv. of cardanol/pentadecyl phenol followed by coupling with 1 equiv. of hydroxyethyl methacrylate. They were polymerized free radically using benzoyl peroxide as the initiator and were characterized by NMR and FTIR, and their molecular weights were determined by gel permeation chromatography. The unique polymer design had sites for self‐organization via hydrogen bonding of the side chain urethane units, π–π stacking interactions of the aromatic units as well as interdigitation of the long C15 alkyl side chains in the polymer. The morphologies of solvent cast polymer films were studied using microscopic techniques such as scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. The polymers exhibited three‐dimensional honeycomb morphology in CHCl3, whereas in tetrahydrofuran, they formed spheres. The direct cardanol‐derived polymer PCIH showed a tendency for multiple morphologies such as spheres and tubes in tetrahydrofuran. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2996–3009, 2009 相似文献
64.
65.
K. D. Krori T. Chaudhury Chandra Rekha Mahanta Ajanta Mazumdar 《General Relativity and Gravitation》1990,22(2):123-130
Some Bianchi-type string-cosmological models are presented here. The physical implications of the models are briefly discussed 相似文献
66.
Gee‐Hong Kuo Catherine Prouty William V. Murray Rekha D. Shah 《Journal of heterocyclic chemistry》2001,38(4):1003-1006
This report describes an improved synthesis of enantiomerically pure (S)‐2‐[4‐(Dimethylamino)phenyl]‐2,3‐dihydro‐N‐[2‐hydroxy‐3‐[4‐[2‐(1‐methylethoxy)‐phenyl]‐1‐piperazinyl]propyl]‐1,3‐dioxo‐1H‐isoindole‐5‐carboxamide (RWJ 69442), a potent and selective αla‐adrenergic receptor antagonist for the treatment of benign prostatic hyperplasia. The synthesis highlights less hazardous reagents, easier purification and higher enantiomeric purity. The N‐benzyl‐N—t‐butoxycarbonyl amine 6 could serve as an enantiomerically pure chiral building block for asymmetric synthesis. 相似文献
67.
Rekha Raghunathan Swetha Mahesula Kranthi Kancharla Preethi Janardhanan Yeshwant L. A. Jadhav Robert Nadeau German P. Villa Robert L. Cook Colleen M. Witt Jonathan A. L. Gelfond Thomas G. Forsthuber William E. Haskins 《Particle & Particle Systems Characterization》2013,30(4):355-364
B‐precursor acute lymphoblastic leukemia (B‐ALL) lymphoblast (blast) internalization of anti‐cytokine receptor‐like factor 2 (CRLF2) antibody‐armored biodegradable nanoparticles (AbBNPs) are investigated. First, AbBNPsaere synthesized by adsorbing anti‐CRLF2 antibodies to poly(D,L‐lactide‐co‐glycolide) (PLGA) nanoparticles of various sizes and antibody surface density (Ab/BNP) ratios. Second, AbBNPs are incubated with CRLF2‐overexpressing (CRLF2+) or control blasts. Third, internalization of AbBNPs by blasts is evaluated by multicolor flow cytometry as a function of receptor expression, AbBNP size, and Ab/BNP ratio. Results from these experiments are confirmed by electron microscopy, fluorescence microscopy, and Western blotting. The optimal size and Ab/BNP for internalization of AbBNPs by CRLF2+ blasts is 50 nm with 10 Ab/BNP and 100 nm with 25 Ab/BNP. These studies show that internalization of AbBNPs in childhood B‐ALL blasts is AbBNP size‐ and Ab/BNP ratio‐dependent. All AbBNP combinations are non‐cytotoxic. It is also shown that CD47 is very slightly up‐regulated by blasts exposed to AbBNPs. CD47 is “the marker of self” overexpressed by blasts to escape phagocytosis, or “cellular devouring”, by beneficial macrophages. The results indicate that precise engineering of AbBNPs by size and Ab/BNP ratio may improve the internalization and selectivity of future biodegradable nanoparticles for the treatment of leukemia patients, including drug‐resistant minority children and Down's syndrome patients with CRLF2+B‐ALL. 相似文献
68.
An organic nonlinear optical crystal 4-aminopyridinium 4-aminobenzenesulfonate 4-ammoniobenzenesulfonate monohydrate (4APABS) was grown by slow evaporation solution growth technique. The cell parameters of grown crystal were confirmed by single crystal X-ray diffraction analysis. High resolution X-ray diffraction studies revealed the crystalline perfection of grown crystal. The functional groups present in title compound were confirmed by FTIR spectral studies. UV–vis spectral studies revealed that the grown crystal is transparent in the entire visible region. Single and multiple shots laser induced surface damage threshold values of the grown crystal were measured using Nd:YAG laser. The relative second harmonic generation efficiency of grown crystal was found to be 2.2 times that of KDP crystal. 相似文献
69.
Jomon P. Jacob Reshma Gopalakrishnan Rekha R. Mallia Jean John Vadakkan Perupparampil A. Unnikrishnan Sreedharan Prathapan 《Journal of Physical Organic Chemistry》2014,27(11):884-891
Herein, we describe diverse reactivity of (anthracen‐9‐yl)methanamines with a few electron‐deficient acetylenes. Depending on the solvent and concentration, (anthracen‐9‐yl)methanamines reacted with acetylenes through one electron transfer, two electron transfer, or Diels–Alder pathways; and under certain conditions, we observed multiple reaction pathways. We have proposed plausible mechanisms to account for various reactions observed by us. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
70.
Synthesis of solar active nanocrystalline ferrite, MFe2O4 (M: Ca, Zn, Mg) photocatalyst by microwave irradiation 总被引:1,自引:0,他引:1
Rekha Dom 《Solid State Communications》2011,151(6):470-473
For the first time, nanocrystalline photocatalysts of spinel MgFe2O4, ZnFe2O4 and orthorhombic CaFe2O4 oxides were synthesized (at low temperature ∼973 K) by microwave sintering, in one sixtieth of the time required to that of the conventional method. A significantly improved crystallinity was obtained for the samples irradiated for longer duration of time (∼10-100 min). The theoretically computed electronic structure of the MFe2O4 (M: Ca, Zn, Mg) systems was respectively correlated with the experimental results obtained from their structural and photocatalytic characterization. The photocatalytic performance was found to be affected by surface area and crystallinity of the photocatalyst. The density functional theory (DFT) calculations of MFe2O4 lattices revealed that M-ion controllably affects the density of sates of the Fe-d orbitals near the Fermi level. Consequently they play an important role in determining the band-energetics and thus the visible light photocatalytic activity for methylene blue degradation. 相似文献