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951.
Marco Mazzotti Stefano Fiorentino Alessandro Ghielmi Massimo Morbidelli Giuseppe Storti 《Macromolecular Symposia》1996,111(1):183-193
A kinetic model suitable to deal with the case of branched polymers produced in emulsion both in the case of chain transfer to polymer and propagation to terminal double bond is briefly presented and numerically solved through the method of the moments. Thanks to the “numerical fractionation” approach, the whole molecular weight distribution of the polymer is evaluated while accounting for the compartmentalized nature of the system. The results of some illustrative calculations concerning the effects upon the molecular properties of the final polymer of starved semibatch monomer feed policies, addition of a chain transfer agent and propagation to terminal double bond are discussed. 相似文献
952.
Antonella Capozzi Daniela Caissutti Vincenzo Mattei Francesca Gado Stefano Martellucci Agostina Longo Serena Recalchi Valeria Manganelli Gloria Riitano Tina Garofalo Maurizio Sorice Clementina Manera Roberta Misasi 《Molecules (Basel, Switzerland)》2022,27(1)
The endocannabinoid system (ECS) exerts immunosuppressive effects, which are mostly mediated by cannabinoid receptor 2 (CBR2), whose expression on leukocytes is higher than CBR1, mainly localized in the brain. Targeted CBR2 activation could limit inflammation, avoiding CBR1-related psychoactive effects. Herein, we evaluated in vitro the biological activity of a novel, selective and high-affinity CBR2 agonist, called JT11, studying its potential CBR2-mediated anti-inflammatory effect. Trypan Blue and MTT assays were used to test the cytotoxic and anti-proliferative effect of JT11 in Jurkat cells. Its pro-apoptotic activity was investigated analyzing both cell cycle and poly PARP cleavage. Finally, we evaluated its impact on LPS-induced ERK1/2 and NF-kB-p65 activation, TNF-α, IL-1β, IL-6 and IL-8 release in peripheral blood mononuclear cells (PBMCs) from healthy donors. Selective CB2R antagonist SR144528 and CBR2 knockdown were used to further verify the selectivity of JT11. We confirmed selective CBR2 activation by JT11. JT11 regulated cell viability and proliferation through a CBR2-dependent mechanism in Jurkat cells, exhibiting a mild pro-apoptotic activity. Finally, it reduced LPS-induced ERK1/2 and NF-kB-p65 phosphorylation and pro-inflammatory cytokines release in human PBMCs, proving to possess in vitro anti-inflammatory properties. JT11 as CBR2 ligands could enhance ECS immunoregulatory activity and our results support the view that therapeutic strategies targeting CBR2 signaling could be promising for the treatment of chronic inflammatory diseases. 相似文献
953.
Stefano De Benedetti Camilla Leogrande Francesco Castagna Giuditta C. Heinzl Matias Pasquali Alessandro L. Heinzl Daniela Lupi Alessio Scarafoni 《Molecules (Basel, Switzerland)》2022,27(1)
The present work aimed to characterize the molecular relationships between structure and function of the seed storage protein β-vignin, the vicilin storage protein of cowpea (Vigna unguiculata, l. Walp) seeds. The molecular characterization of β-vignin was carried out firstly by assessing its thermal stability, under different conditions of pH and ionic strength, by thermal shift assay (TSA) using SYPRO Orange fluorescent dye. Secondly, its aggregation propensity was evaluated using a combination of chromatographic and electrophoretic techniques. Two forms of β-vignin were considered: the native form purified from mature quiescent seeds, and a stable breakdown intermediate of 27 kDa produced while seeds germinate. TSA is a useful tool for determining and following over time the structural changes that occur to the protein during germination. The main result was the molecular characterization of the 27 kDa intermediate breakdown polypeptide, which, to the best of our knowledge, has never been described before. β-vignin seems to retain its trimeric conformation despite the evident degradation of its polypeptides. 相似文献
954.
955.
956.
Giorgio Papeschi Stefano Mancuso Anna Maria Marras 《Journal of Solid State Electrochemistry》2000,4(6):325-329
The electrochemical behaviour of a Cu/CuSe electrode was studied in order to define its selectivity towards cupric ions,
Nerstian response, limit of detection and response time. The chalcogenide electrode was prepared by cathodic deposition of
Se and subsequent formation of a thin layer of CuSe on a copper substrate. A Cu/CuSe microelectrode was prepared using copper
wire 75 μm in diameter. The dimensions and response time (<0.5 s) allowed use of this electrode in the “vibrating probe method”
with the aim of measuring net influxes as well as effluxes of copper(II) ions in Olea europaea roots. The electrode potential was measured along the root at a distance of 5 μm from the surface for 5 s, and then again
for 5 s at a distance of 55 μm, moving the microelectrode with respect to the root surface by steps with a frequency of 0.1 Hz.
The potentials measured at the two extremes of vibration were then converted to copper(II) concentrations. Substitution of
these values in Fick's law yields the flux, assuming the diffusion constant D for copper ions in aqueous solutions. The results enabled us to detect copper(II) fluxes as small as 0.05 pmol cm−2 s−1. Copper(II) influx showed marked spatial and temporal features: it was highest at about 1.5 mm from the root apex and exhibited
an oscillatory pattern in time.
Received: 29 September 1999 / Accepted: 11 January 2000 相似文献
957.
Gabriele Albertin Stefano Antoniutti Sonia Pizzol 《Journal of organometallic chemistry》2004,689(9):1639-1647
Chloro-complexes [OsCl(N-N)P3]BPh4 (1, 2) [N-N=2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen); P=P(OEt)3 and PPh(OEt)2] were prepared by allowing OsCl4(N-N) to react with zinc dust in the presence of phosphites. Treatment of the chloro-complexes 1, 2 with NaBH4 yielded, in the case of bpy, the hydride [OsH(bpy)P3]BPh4 (4) derivatives. Mono-phosphite [OsCl(bpy)2P]BPh4 (3) complexes were also prepared by reacting the [OsCl2(bpy)2]Cl compound with zinc dust in the presence of phosphite. Protonation reaction of the hydride [OsH(bpy)P3]+ (4) cations with Brønsted acid was studied and led to thermally unstable (above 0 °C) dihydrogen [Os(η2-H2)(bpy)P3]2+ (4*) derivatives. The presence of the H2 ligand is supported by variable-temperature NMR spectra and T1min measurements. Carbonyl [Os(CO)(bpy){P(OEt)3}3](BPh4)2 (5), nitrile [Os(CH3CN)(bpy){P(OEt)3}3](BPh4)2 (6), and hydrazine [Os(bpy)(NH2NH2){P(OEt)3}3](BPh4)2 (7) complexes were prepared by substituting the H2 ligand in the η2-H2 (4*) derivatives. Aryldiazene complex [Os(C6H5NNH)(bpy){P(OEt)3}3](BPh4)2 (8) was also obtained by allowing the hydride [OsH(bpy)P3]BPh4 to react with phenyldiazonium cation. 相似文献
958.
Francesca Loschi Marta Faggian Stefania Sut Irene Ferrarese Erica Maccari Gregorio Peron Stefano DallAcqua 《Molecules (Basel, Switzerland)》2022,27(6)
Products based on plants containing hydroxyanthracene derivatives (HADs)—such as Rheum, Cassia, and Aloe species—are widely used in food supplements or nutraceuticals due to their laxative effects. A more restricted control of HAD contents in food supplements has been implemented by EU Regulation 2021/468, in order to increase the safety of these preparations. Due to their toxicity, aloin A, aloin B, aloe emodin, emodin, and the synthetic derivative danthron have been listed as prohibited substances in food supplements, being tolerated in amounts < 1 mg kg−1 in marketed products. In this work, we report the development of a sensitive and fast LC–DAD–MS-based procedure for the determination of these five compounds in food supplements and plant materials or extracts. The entire procedure includes a simple sample preparation step, where target analytes are concentrated by means of solvent extraction and evaporative concentration (solid samples), or by lyophilisation (liquid samples). The average LOQ of 0.10 mg/L, LOD of 0.03 mg/L, accuracy, and precision with CVs below 12.72 were obtained for the studied analytes. This method is suitable for assessing the compliance of commercial products and raw materials with EU Regulation 2021/468. Furthermore, the proposed method can represent a starting point for the development of a unique and standardised analytical approach for the determination of other HADs under the attention of EU authorities. 相似文献
959.
Rosaria Volpini Emidio Camaioni Stefano Costanzi Sauro Vittori Gloria Cristalli 《Helvetica chimica acta》1998,81(12):2326-2331
Coupling of 4,6-dichloro-1H-imidazo[4,5-c]pyridine (2,6-dichloro-3-deaza-9H-purine) ( 1 ) with 1,2-O-di-acetyl-5-O-benzoyl-3-deoxy-β-D -ribofuranose ( 2 ), employing the acid-catalyzed fusion method, is reported (Scheme 1). The condensation reaction was regioselective and gave the three N1-glycosylation products 3 – 5 , whereas no N3-nucleosides were detected. Treatment of 3 – 5 with methanolic ammonia afforded the corresponding deprotected nucleosides 6 – 8 . Compounds 6 and 7 were assigned the structure of the β-D - and α-D -anomeric N1-(3′-deoxyribo)nucleosides, respectively. The third derivative 8 proved to be the α-D -anomer of a 3′-deoxyarabinonucleoside deriving from epimerization at C(2) of the sugar. The 2-chloro- and N6-substituted derivatives 9 , 11 , and 13 of 3′-deoxy-3-deazaadenosine ( 10 ) and of its α-D -anomer 12 can be obtained from these versatile synthons (Schemes 2 and 3). 相似文献
960.
B. Doug Park Mainak Poddar Stefano Vidussi 《Transactions of the American Mathematical Society》2007,359(6):2651-2662
We construct an infinite family of homologous, non-isotopic, symplectic surfaces of any genus greater than one in a certain class of closed, simply connected, symplectic four-manifolds. Our construction is the first example of this phenomenon for surfaces of genus greater than one.