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951.
Cyclic voltammetry of ferrocene at glassy carbon electrode in acetonitrile (ACN), ο-nitrophenyloctylether (NPOE) and ACN-NPOE mixture with 0.2 M tetrabutylammonium tetrafluoroborate (TBABF4) were investigated. Both cathodic and anodic peak current were diffusion-controlled at any NPOE fraction. However, the peak current was decreased with the increasing NPOE fraction. In addition, the peak potential difference increased not only with an increase in the NPOE fraction but also in the scan rate, while the values of half-wave potential did not vary largely with the fraction or the scan rate. This indicated that the variation of peak current and peak potential should be due to the variation of the solution resistance. In order to demonstrate this assumption, the conductance of TBABF4 in ACN, NPOE, and ACN-NPOE mixture were determined by AC impedance. All of the solution conductances were inversely linear to the viscosity of the solvent, which was increased with the fraction of NPOE. The calculated ionization constant of TBABF4 in ACN was 2.8 times of that in NPOE. TBABF4 in ACN can work as a supporting electrolyte, whereas they work partly in NPOE. 相似文献
952.
Gwang-Sik Song Youn-Jung Heo Jeong Ju Baek Hyosun Lee Geun Yeol Bae Kyung Ho Choi Won-Gun Koh Gyojic Shin 《Journal of polymer science. Part A, Polymer chemistry》2021,59(4):340-352
In this article, photosensitive polyimides (PSPIs) with photosensitive groups, o-nitrobenzyl ether groups (Nb), were successfully synthesized based on 2,2′-dihydroxy benzophenone-3,3′,4,4′-tetracarboxylic dianhydride and on diamine containing ethylene glycol chains (ODA). Also, a series of polyimide (PI), ODA-1-PI, ODA-3-PI, and ODA-5-PI with a number of ethylene glycol chains of 1, 3, and 5 were prepared to investigate the relationship between structure and solubility. Interestingly, ODA-5-PI, which possesses a large number of ethylene glycols, exhibited the most excellent solubility. Therefore, due to the good solubility of ODA-5-PI in organic solvents and alkaline solutions, a PSPI, poly(1,4-phenyleneoxy-3,6,9,12,15-pentaoxaoctane-1,4-phenylene-2,2′-di[2-nitrobenzyloxy]benzophenone-3,3′,4,4′-tetracarboxdiimide), named ODA-5-PSPI, was synthesized by linking Nb, which is a photosensitive group. Aiming at producing positive tone patterns, the synthesized ODA-5-PSPI was exposed to UV irradiation and then to a post-exposure bake. Afterward, it was developed using a 2.38 wt% tetramethylammonium hydroxide solution. Furthermore, a photoacid generator (PAG) was additionally incorporated for a micropatterning process. Notably, in the presence of the PAG, the photocleavage of ODA-5-PSPI occurred not only by the intramolecular rearrangement of Nb but also by its hydrolysis reaction. As a result, due to the synergistic effect of photocleavage, the micropatterning of ODA-5-PSPI with PAG could be clearly obtained with less energy (2.0 J/cm2) compared with that without PAG (3.6 J/cm2). Therefore, through the addition of PAG, the photosensitivity was improved by 45%. 相似文献
953.
Mei‐Chun Lee Kuei‐Ju Cheng Shih‐Ming Chen Yi‐Chieh Li Kazuhiro Imai Chun‐Ming Lee Jen‐Ai Lee 《Biomedical chromatography : BMC》2019,33(11)
Atorvastatin (ATO) inhibits the synthesis of nonsteroidal isoprenoid compounds and possesses a pleiotropic effect. However, the detailed mechanism of ATO in preventing gentamicin (GM)‐induced renal injury remains obscure. Although underlying multifaceted mechanisms involving GM‐induced nephrotoxicity were well known, further work on elucidating the essential mechanism was needed. Using a fluorogenic derivatization–liquid chromatography tandem mass spectrometry proteomic method (FD‐LC–MS/MS method), we investigated the effects and mechanisms of ATO treatment on GM‐induced nephrotoxicity in rats. Consequently, 49 differentially expressed proteins were identified. The most significant mechanisms of nephrotoxicity caused by GM were mitochondrial dysfunction, fatty acid metabolism and oxidative stress. Their upstream regulator was found to be PPARα. The proteins involved in GM nephrotoxicity were sodium–hydrogen exchanger regulatory factor (SLC9A3R1), cathepsin V (CTSV), macrophage migration inhibitory factor (MIF) and RhoGDP dissociation inhibitor alpha (ARHGDIA). After ATO intervention, we observed a reversed enrichment pattern of their expression, especially in CTSV and SLC9A3R1 (P‐value<0.05). We predicted that ATO may improve abnormal phospholipid metabolism and phospholipidosis caused by GM and also alleviate cell volume homeostasis and reverse the interference of GM with the transporter. Furthermore, proteomic results also provided clues as to GM‐induced nephrotoxicity biomarkers such as CTSV and transthyretin. 相似文献
954.
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956.
Margarita Juárez-Montiel J. Antonio Ibarra Griselda Chávez-Camarillo César Hernández-Rodríguez Lourdes Villa-Tanaca 《Applied biochemistry and biotechnology》2014,172(5):2530-2539
Dipeptidyl aminopeptidases are enzymes involved in the posttranslational control of bioactive peptides. Here we identified the gene dapUm in Ustilago maydis by homology with other fungal dipeptidyl aminopeptidases. Analysis of the dapUm-deduced amino acid sequence indicated that it encodes for membrane-type serine protease with a characteristic prolyl oligopeptidase catalytic motif triad: Ser, Asp, His. In order to overexpress the DapUm, the gene encoding for it was cloned and transformed into Pichia. Using this system, we observed a ~125-kDa recombinant protein with an optimal enzymatic activity at pH 6.0 and at 40 °C for the Ala-Pro-p-nitroanilide substrate and an experimental pH of 6.9. U. maydis DapUm was specifically inhibited by phenylmethylsulfonyl fluoride and Pefabloc, confirming the presence of a serine residue in the active site. To our knowledge, this study is the first report on the cloning and expression of a DPP IV dipeptidyl aminopeptidase from a basidiomycete organism. Moreover, the use of recombinant DapUm will allow us to further study and characterize this enzyme, in addition to testing chemical compounds for pharmaceutical purposes. 相似文献
957.
The denitrification of low-temperature flue gas is a difficult problem facing the industry. OH radicals can effectually oxidize NO in flue gas, which can achieve denitrification of low-temperature flue gas. Heterogeneous Fenton reaction is an important method for the formation of OH radicals. A four-step reaction mechanism of the formation of OH radicals by heterogeneous Fenton reaction is proposed and investigated in this paper. Theoretical results show that activation energy of the formation of OH radicals catalyzed by ZSM5-Si/Fe is much lower than that without catalyst. After doping Al/Ce/Ti, the activation energy is further reduced significantly. The activity is related to the active center atom of the catalyst. By comparing, ZSM5-Ce/Al–Fe has better catalytic performance because of its more fluffy structure. This study would provide an important theoretical reference for the design of the catalysts in heterogeneous Fenton reaction and their industrial applications. 相似文献
958.
<正>In vivo fluorescence imaging in the second near-infrared(NIR-Ⅱ) window (1000–1700 nm) has been emerging as a new powerful imaging technique and demonstrated tremendous potential in life sciences and biomedical applications, given its advances in reducing photon scattering, light absorption, and autofluorescence [1,2]. In particular, ex- 相似文献
959.
Lei Sang Sheng-Li Chen Guimei Yuan Zheng Zhou Rui Li Aicheng Chen Min Zheng Ju You State 《天然气化学杂志》2012,(3):352-359
Mesoporous γ-aluminas with large pore size(up to 19 nm,denoted as MA19) are prepared from dispersed pseudo-boehmite using pluronic P123 as template.It is found that these mesoporous alumina supported rhenium oxide catalysts were more active and have far longer working life-span in gas-phase metathesis of 1-butene and 2-butene to propene than rhenium oxide on conventional alumina with small pore size(5 nm).At 60°C and atmospheric pressure with WHSV = 1 h-1,the similar stable conversions of butene(ca.55%) for all the 13 wt% Re 2 O 7 /alumina catalysts were obtained near the chemical equilibrium,and the stable working life-spans of Re 2 O 7 /MA19 were far longer than that of Re 2 O 7 /Al 2 O 3,being about 70 h and 20 h,respectively. 相似文献
960.
Jingjing Hui Lei Bao Siqiao Li Yi Zhang Yimei Feng Prof. Dr. Lin Ding Prof. Dr. Huangxian Ju 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(28):8251-8255
Live cell imaging of protein‐specific glycoforms is important for the elucidation of glycosylation mechanisms and identification of disease states. The currently used metabolic oligosaccharide engineering (MOE) technology permits routinely global chemical remodeling (GCM) for carbohydrate site of interest, but can exert unnecessary whole‐cell scale perturbation and generate unpredictable metabolic efficiency issue. A localized chemical remodeling (LCM) strategy for efficient and reliable access to protein‐specific glycoform information is reported. The proof‐of‐concept protocol developed for MUC1‐specific terminal galactose/N ‐acetylgalactosamine (Gal/GalNAc) combines affinity binding, off‐on switchable catalytic activity, and proximity catalysis to create a reactive handle for bioorthogonal labeling and imaging. Noteworthy assay features associated with LCM as compared with MOE include minimum target cell perturbation, short reaction timeframe, effectiveness as a molecular ruler, and quantitative analysis capability. 相似文献