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排序方式: 共有956条查询结果,搜索用时 31 毫秒
831.
Gizelda O.D. EstradaAna Luiza P. Blanco Joaquim F.M. da SilvaChristian G. Alonso Nádia R.C. Fernandes-MachadoLucio Cardozo-Filho Rodrigo O.M.A. de SouzaLeandro S.M. e Miranda 《Tetrahedron letters》2012,53(9):1089-1093
Pd/Nb2O5 was prepared, characterized and tested in Suzuki-Miyaura cross-coupling reactions under ligand-free conditions. High yields and selectivities were observed within short reaction times and very low palladium loadings. 相似文献
832.
Ashot S. Saghyan Ani S. Dadayan Slavik A. Dadayan Anna F. Mkrtchyan Arpine V. Geolchanyan Luiza L. Manasyan Hrant R. Ajvazyan Victor N. Khrustalev Hasmik H. Hambardzumyan Victor I. Maleev 《Tetrahedron: Asymmetry》2010,21(24):2956-2965
New fluorine-containing chiral auxiliaries (S)-N-(2-benzoylphenyl)-1-(2-fluorobenzyl)-, (S)-N-(2-benzoylphenyl)-1-(3-fluorobenzyl)-, and (S)-N-(2-benzoylphenyl)-1-(4-fluorobenzyl)-pyrrolidine-2-carboxamide and their NiII complexes of Schiff bases with glycine and alanine have been synthesized. The greater efficiency of the complexes in terms of faster reaction rates and stereoselectivities in the asymmetric synthesis of (S)-α-amino acids has also been demonstrated. 相似文献
833.
Mariana Kuneva Svetlen Tonchev Diana Nesheva Peter Atanasov 《Solid State Sciences》2010,12(11):1870-1872
A combination of methods was used for analysis of the phase composition of proton-exchanged layers in Y-cut lithium niobate. Mode spectra were used for the determination of phases. Vibration spectra allow some comparative and semi-quantitative estimations of the thickness of phase sub-layers to be made. The demonstrated method can contribute to adjustment of fabrication conditions for obtaining of defined phase compositions needed for waveguide devices with improved stability and characteristics.It was shown that deep and strongly protonated waveguides in Y-cut LiNbO3 could be obtained at specific technological regimes. 相似文献
834.
Luiza M.S. Nunes Tiago B. Moraes Lucio L. Barbosa Luiz H. Mazo Luiz A. Colnago 《Analytica chimica acta》2014
All attempts to use in situ13C NMR in spectroelectrochemical studies, using static cells and unlabeled substrates, have failed due to the very long average time (several hours). In this paper, we demonstrated that steady-state free precession (SSFP) pulse sequence can enhance signal to noise ratio and reduces the average time of 13C NMR signals by more than one order of magnitude. The results showed that each 13C NMR spectrum during the electrochemical reduction of 9-chloroanthracene, in a static cell, can be acquired in eleven minutes. This short averaging time allowed the analysis of the reaction every 30 min during 3 h. The phase and truncation anomalies present in SSFP spectra were minimized using Traff apodization function and Krylov basis diagonalization method (KBDM). 相似文献
835.
Ren Cai Dr. Yaping Du Wenyu Zhang Huiteng Tan Tao Zeng Xin Huang Hongfen Yang Chunping Chen Hai Liu Jixin Zhu Shengjie Peng Jing Chen Prof. Yuliang Zhao Prof. Haichen Wu Prof. Yizhong Huang Prof. Rong Xu Prof. Tuti Mariana Lim Prof. Qichun Zhang Prof. Hua Zhang Prof. Qingyu Yan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(5):1568-1572
836.
The flash points of three organic binary mixtures containing alcohols were measured in the present work. The experimental data was obtained using the Pensky-Martens closed cup tester. The experimental data were compared with the values calculated by the Liaw model. Activity coefficients were calculated by the Wilson equation and NRTL equation. The accuracy of predicted flash point values is dependent on the thermodynamic model used for activity coefficient. 相似文献
837.
Suzanne Letourneau Luiza Hernandez Andrea N. Faris Dana M. Spence 《Analytical and bioanalytical chemistry》2010,397(8):3369-3375
Recently, estrogens have been reported to have protective effects against experimental autoimmune encephalomyelitis (EAE),
a murine model of multiple sclerosis (MS). Although the molecular mechanism for such a protective effect is currently incomplete,
we hypothesized that estradiol may reduce the release of ATP from erythrocytes (ERYs), thereby lowering the production of
nitric oxide (NO) by endothelial cells. Here, we report on the use of a microfluidic device to investigate the direct effects
of the estrogen estradiol on endothelial cell nitric oxide production. In addition, the incorporation of a thin polycarbonate
membrane into the device enabled the passage of ERYs through the device to determine indirect effects of estradiol on NO production
that may be meditated by ERYs. When these ERYs were incubated with increasing concentrations of estradiol, the NO production
from the endothelial cells was attenuated to a value that was only 59 ± 7% of ERYs in the absence of estradiol. This decrease
in NO production coincides with reductions in ERY-derived ATP release in the presence of estradiol. Estradiol is typically
reported to have NO-stimulating effects; however, such reports have employed in vitro experimental designs that include only
a single cell type. To demonstrate the potential importance of this attenuation of ATP from ERYs, results from a small-scale
study show that the ATP release obtained from healthy controls was 138 ± 21 nM (n = 18) while the release from the ERYs obtained from people with MS was 375 ± 51 nM (n = 11). The studies reported here involving multiple cells types (endothelial cells and ERYs) may lead to a reappraisal of
the in vivo activities of estradiol. 相似文献
838.
839.
Mariana Spulber Mariana Pinteala Adrian Fifere Costel Moldoveanu Ionel Mangalagiu Valeria Harabagiu Bogdan C. Simionescu 《Journal of inclusion phenomena and macrocyclic chemistry》2008,62(1-2):135-142
Complexation between methyl β-cyclodextrin (Me βCD) and sulconazole nitrate (SULC) was realized both under freeze drying and ultrasonication conditions. The process was carried out in solution and in solid state. In solution, the complexation was evaluated using solubility studies, nuclear magnetic resonance spectroscopy (1H-NMR) and UV–Vis absorption studies. In the solid state, differential scanning calorimetry (DSC), and X-ray diffraction studies were used. Solubility studies indicate the existence of inclusion complexes between SULC and Me βCD. 1H-NMR data showed that the inclusion complexes have different structures, according with the method we used for synthesis: for the freeze dried method the complex is obtained by complexation of dichlorobenzene ring of SULC into inner cavity of CD while for ultrasonication method the complex is obtained by complexation of imidazole graph of SULC into the CD molecule. DSC and X-ray studies bring supplementary information concerning the formation of complex Me βCD–SULC. As a result of the inclusion process into Me βCD, the solubility of SULC increase significant, being 10 times more comparative with the pure drug. We anticipate that these modifications will have a significant impact on the biological effects of the drug, making the SULC–Me βCD complex an appropriate candidate for a new drug delivery system. 相似文献
840.
Temitope T. Abiola Benjamin Rioux Josene M. Toldo Jimmy Alarcan Jack M. Woolley Matthew A. P. Turner Daniel J. L. Coxon Mariana Telles do Casal Cdric Peyrot Matthieu M. Mention Wybren J. Buma Michael N. R. Ashfold Albert Braeuning Mario Barbatti Vasilios G. Stavros Florent Allais 《Chemical science》2021,12(46):15239
Light-to-heat conversion materials generate great interest due to their widespread applications, notable exemplars being solar energy harvesting and photoprotection. Another more recently identified potential application for such materials is in molecular heaters for agriculture, whose function is to protect crops from extreme cold weather and extend both the growing season and the geographic areas capable of supporting growth, all of which could help reduce food security challenges. To address this demand, a new series of phenolic-based barbituric absorbers of ultraviolet (UV) radiation has been designed and synthesised in a sustainable manner. The photophysics of these molecules has been studied in solution using femtosecond transient electronic and vibrational absorption spectroscopies, allied with computational simulations and their potential toxicity assessed by in silico studies. Following photoexcitation to the lowest singlet excited state, these barbituric absorbers repopulate the electronic ground state with high fidelity on an ultrafast time scale (within a few picoseconds). The energy relaxation pathway includes a twisted intramolecular charge-transfer state as the system evolves out of the Franck–Condon region, internal conversion to the ground electronic state, and subsequent vibrational cooling. These barbituric absorbers display promising light-to-heat conversion capabilities, are predicted to be non-toxic, and demand further study within neighbouring application-based fields.The synthesis and photophysical properties of phenolic barbiturics are reported. These molecules convert absorbed ultraviolet light to heat with high fidelity and may be suitable for inclusion in foliar sprays to boost crop protection and production. 相似文献