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951.
Bao‐Zhu Yang Xin Zhou Tao Liu Fu‐Quan Bai Hong‐Xing Zhang 《International journal of quantum chemistry》2010,110(9):1605-1614
The electronic structures and spectroscopic properties of the three tridentate cyclometalated Platinum(II) complexes PtL1Cl [L1 = 1,3‐di(2‐pyridyl)‐5‐methyl‐benzene] ( 1 ), PtL2Cl [L2 = 1‐(2‐pyridyl)‐3‐(1‐pyrazolyl)‐5‐methyl‐benzene] ( 2 ), and PtL3Cl [L3 = 1,3‐bis(1‐pyrazolyl)‐5‐methyl‐benzene] ( 3 ) were calculated to explore their spectroscopic nature. The geometry structures of 1 – 3 in the ground and excited states were optimized under the density functional theory (DFT) and the single‐excitation configuration interaction (CIS) level, respectively. The absorption and emission spectra in CH2Cl2 solution were calculated by the time‐dependent density‐functional theory (TD‐DFT) with the polarized continuum model solvent model. As revealed from the calculations, the LUMO of 1 and 2 are localized on phenyl and pyridyl, but that of 3 has 50.3% π*(pyrazolyl) and 47.8% π*(phenyl). The energy gap of the d‐d state was much greater than that of the CT transitions. With the replacement of pyridyl by pyrazolyl, the electron‐donating ability of N atom decreases, whereas the LUMO energy level increases. The lowest‐energy absorptions and emissions are blue‐shifted in the order 1 > 2 > 3 , which are assigned as the ILCT/MLCT/LLCT and 3ILCT/3MLCT/3LLCT characters, respectively. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
952.
Zhi‐Yong Xiao Xia‐Chang Wang Gui‐Ping Zhang Zhong‐Liang Huang Li‐Hong Hu 《Helvetica chimica acta》2010,93(4):803-810
Five new terpenoids, including four eudesmane‐type sesquiterpenoids, 1 – 4 , and one labdane‐type diterpenoid, 6 , together with ten known compounds, were isolated from the roots of Chloranthus spicatus. The structures and their relative configurations were mainly established by 1D‐ and 2D‐NMR spectra, and MS experiments. 相似文献
953.
Yue Hu Xiao‐Dong Li Guo‐Yu Li Ning Li Wen‐Jian Zuo Yi‐Mei Zeng He Meng Xian Li Jin‐Hui Wang 《Helvetica chimica acta》2010,93(5):1019-1024
Two new sesquiterpenoids, ferulactones A and B ( 1 and 2 , resp.), have been isolated from the roots of Ferula ferulaeoides (Steud.) Korov . Their structures and relative configurations were established by analysis of spectroscopic data. Their absolute configuration was assigned by application of the CD technique. 相似文献
954.
Du‐Qiang Luo Wen‐Liang Zhu Xiao‐Long Yang Shu‐Juan Liang Zhi‐Ran Cao 《Helvetica chimica acta》2010,93(6):1209-1215
Two new daphniphyllum alkaloids named 2‐hydroxyyunnandaphnine D ( 1 ) and methyl 7‐hydroxyhomodaphniphyllate ( 2 ), together with eight known alkaloids, daphnioldhanin D, calyciphylline F, calyciphylline B, deoxycalyciphylline B, daphnicyclidin H, macropodumine C, 9,10‐epoxycalycine A, and yunnandaphnine A, were isolated from the stems and leaves of Daphniphyllum calycinum. Their structures and relative configurations were established on the basis of spectral evidence (including 2D‐NMR) and subsequently confirmed by a single‐crystal X‐ray crystallographic diffraction analysis. 相似文献
955.
956.
Spirooxindole amides can be prepared by the intramolecular addition of functionalized indoles into acylimines that are accessed from nitriles by hydrozirconation and acylation. The stereochemical outcome at the quaternary center was controlled by the steric bulk of the substituent at the 2-position of the indole unit. The products are well-suited for diversification to prepare libraries. 相似文献
957.
A simple and efficient microwave-assisted extraction of polyphenols from industrial apple pomace was developed and optimized by the maximization of the yield using response surface methodology. A Box-Behnken design was used to monitor the effect of microwave power, extraction time, ethanol concentration and ratio of solvent to raw material (g/mL) on the polyphenols yield. The results showed that the optimal conditions were as follows: microwave power 650.4?W, extraction time 53.7?s, ethanol concentration 62.1% and ratio of solvent to raw material 22.9:1. Validation tests indicated that the actual yield of polyphenols was 62.68±0.35?mg gallic acid equivalents per 100?g dry apple pomace with RSD=0.86% (n=5) under the optimal conditions, which was in good agreement with the predicted yield and higher than those of reflux and ultrasonic-assisted extraction methods. HPLC analysis indicated that the major polyphenols of apple pomace consisted of chlorogenic acid, caffeic acid, syrigin, procyanidin B2, (-)-epicatechin, cinnamic acid, coumaric acid, phlorizin and quercetin, of which procyanidin B2 had the highest content of 219.4?mg/kg. 相似文献
958.
DNA methylation is one of the most important epigenetic modification types, which plays a critical role in gene expression. High efficient surveying of whole genome DNA methylation has been aims of many researchers for long. Recently, the rapidly developed massively parallel DNA‐sequencing technologies open the floodgates to vast volumes of sequence data, enabling a paradigm shift in profiling the whole genome methylation. Here, we describe a strategy, combining methylated DNA immunoprecipitation sequencing with peak search to identify methylated regions on a whole‐genome scale. Massively parallel methylated DNA immunoprecipitation sequencing combined with methylation DNA immunoprecipitation was adopted to obtain methylated DNA sequence data from human leukemia cell line K562, and the methylated regions were identified by peak search based on Poison model. From our result, 140 958 non‐overlapping methylated regions have been identified in the whole genome. Also, the credibility of result has been proved by its strong correlation with bisulfite‐sequencing data (Pearson R2=0.92). It suggests that this method provides a reliable and high‐throughput strategy for whole genome methylation identification. 相似文献
959.
960.
In the present study, an ultra-performance liquid chromatography method with diode array detection (UPLC-DAD) was developed for the analysis and determination of leonurine from motherwort (Leonurus japonicus), a traditional Chinese medicinal plant. This method was validated in terms of specificity, linearity (R(2) = 0.9995, linear range: 0.005 ~ 0.5 mg/mL), precision (< 5.0% RSD), and recovery (103.2%). The extracted amount of leonurine is 0.15 mg/g. Moreover, the target analyte was identified or tentatively characterized using UPLC coupled with electrospary tandem mass spectrometry (UPLC-ESI-MS). 相似文献