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831.
A general route to 1,2-oxazines and open chain oximes bearing a 1H-tetrazolyl substituent via Diels-Alder reaction of 3-(tetrazol-5-yl)-nitrosoalkenes is reported. It was also demonstrated that reduction of these adducts followed by deprotection of the tetrazolyl group give 5-(1-aminoalkyl)-1H-tetrazoles, α-amino acid analogues. 相似文献
832.
Santa GL Bernardino SM Magalhães S Mendes V Marques MP Fonseca LP Fernandes P 《Applied biochemistry and biotechnology》2011,165(1):1-12
The present work aims to provide the basic characterization of sol–gel immobilized inulinase, a biocatalyst configuration
yet unexploited, using as model system the hydrolysis of inulin to fructose. Porous xerogel particles with dimensions in slight
excess of 10 μm were obtained, yielding an immobilization efficiency of roughly 80%. The temperature– and pH–activity profiles
displayed a broader bell-shaped pattern as a result of immobilization. In the latter case, a shift of the optimal pH of 0.5
pH units was observed towards a less acidic environment. The kinetic parameters estimated from the typical Michaelis–Menten
kinetics suggest that immobilization in sol–gel did not tamper with the native enzyme conformation, but on the other hand,
entrapment brought along mass transfer limitations. The sol–gel biocatalyst displayed a promising operational stability, since
it was used in more than 20 consecutive 24-hour batch runs without noticeable decay in product yield. The performance of sol–gel
biocatalyst particles doped with magnetite roughly matched the performance of simple sol–gel particles in a single batch run.
However, the operational stability of the former proved poorer, since activity decay was evident after four consecutive 24-hour
batch runs. 相似文献
833.
Braulio Insuasty Alberto Insuasty Alexis Tigreros Jairo Quiroga Rodrigo Abonia Manuel Nogueras Justo Cobo Marcos Derita Susana Zacchino 《Journal of heterocyclic chemistry》2011,48(2):347-350
This work describes the synthesis and antifungal evaluation of 5‐arylidene‐(Z)‐2‐(1,1‐dicyanomethylene)‐1,3‐thiazol‐4‐ones 5 obtained from the reaction of 2‐(1,1‐dicyanomethylene)‐1,3‐thiazol‐4‐one 3 and benzaldehydes 4. The starting material 3 was synthesized by a condensation reaction of rhodanine 1 and malononitrile 2. The structures of the obtained products were established by IR, NMR, mass spectrometry, and elemental analysis. J. Heterocyclic Chem., (2011). 相似文献
834.
Susana Coito George Rupp Eef van Beveren 《The European Physical Journal C - Particles and Fields》2011,71(10):1762
The nature of the X(3872) enhancement is analyzed in the framework of the Resonance-Spectrum Expansion, by studying it as a regular J
PC
=1++ charmonium state, though strongly influenced and shifted by open-charm decay channels. The observed but Okubo–Zweig–Iizuka-forbidden
ρ
0
J/ψ and ωJ/ψ channels are coupled as well, but effectively smeared out by using complex ρ
0 and ω masses, in order to account for their physical widths, followed by a rigorous algebraic procedure to restore unitarity. A
very delicate interplay between the D
0
D
∗0, ρ
0
J/ψ, and ωJ/ψ channels is observed. The data clearly suggest that the X(3872) is a very narrow axial-vector c[`(c)]c\bar{c} resonance, with a pole at or slightly below the D
0
D
∗0 threshold. 相似文献
835.
Rafaela Dias Oliveira Snia Pires Celeiro Catarina Barbosa-Matos Ana Sofia Freitas Susana M. Cardoso Marta Viana-Pereira Cristina Almeida-Aguiar Ftima Baltazar 《Molecules (Basel, Switzerland)》2022,27(11)
Melanoma is the most aggressive and life-threatening skin cancer type. The melanoma genome is the most frequently mutated, with the BRAF mutation present in 40–60% of melanoma cases. BRAF-mutated melanomas are characterized by a higher aggressiveness and progression. Adjuvant targeted treatments, such as BRAF and MEK inhibitors, are added to surgical excision in BRAF-mutated metastatic melanomas to maximize treatment effectiveness. However, resistance remains the major therapeutic problem. Interest in natural products, like propolis, for therapeutic applications, has increased in the last years. Propolis healing proprieties offer great potential for the development of novel cancer drugs. As the activity of Portuguese propolis has never been studied in melanoma, we evaluated the antitumoral activity of propolis from Gerês (G18.EE) and its fractions (n-hexane, ethyl acetate (EtOAc), and n-butanol) in A375 and WM9 melanoma cell lines. Results from DPPH•/ABTS• radical scavenging assays indicated that the samples had relevant antioxidant activity, however, this was not confirmed in the cell models. G18.EE and its fractions decreased cell viability (SRB assay) and promoted ROS production (DHE/Mitotracker probes by flow cytometry), leading to activation of apoptotic signaling (expression of apoptosis markers). Our results suggest that the n-BuOH fraction has the potential to be explored in the pharmacological therapy of melanoma. 相似文献
836.
Ana Sofia Freitas Marta Costa Olívia Pontes Veronique Seidel Fernanda Proena Susana M. Cardoso Rui Oliveira Ftima Baltazar Cristina Almeida-Aguiar 《Molecules (Basel, Switzerland)》2022,27(13)
Renal cell carcinoma is the most lethal cancer of the urological system due to late diagnosis and treatment resistance. Propolis, a beehive product, is a valuable natural source of compounds with bioactivities and may be a beneficial addition to current anticancer treatments. A Portuguese propolis sample, its fractions (n-hexane, ethyl acetate, n-butanol and water) and three subfractions (P1–P3), were tested for their toxicity on A498, 786-O and Caki-2 renal cell carcinoma cell lines and the non-neoplastic HK2 kidney cells. The ethyl acetate fraction showed the strongest toxicity against A498 (IC50 = 0.162 µg mL−1) and 786-O (IC50 = 0.271 µg mL−1) cells. With similar toxicity against 786-O, P1 (IC50 = 3.8 µg mL−1) and P3 (IC50 = 3.1 µg mL−1) exhibited greater effect when combined (IC50 = 2.5 µg mL−1). Results support the potential of propolis and its constituents as promising coadjuvants in renal cell carcinoma treatment. 相似文献
837.
The rotational spectrum of laser-ablated gallic acid has been recorded using CP-FTMW spectroscopy. Two rotamers have been detected, and their rotational spectra have been assigned and analyzed to obtain the molecular spectroscopic parameters. The observed rotamers have been unambiguously identified in the light of theoretical computations, based on the comparison of the experimental line intensities and rotational parameters with the rotational constants and electric dipole moments predicted from theoretical calculations. The values of the planar inertial moments confirm that the observed conformers are planar, and their relative stability and population have been determined from relative intensity measurements. The B3LYP-D3/6-311++G(2d,p) level has been shown to be the best method among a series of levels normally used to predict the rotational parameters in rotational spectroscopy. In the observed conformers, the three adjacent OH groups are arranged in a sequential form, and the only difference between them lies in the orientation of the COOH group. Although weak attractive OH···O interactions seem to exist, the analysis of the electron density topology does not show the existence of any critical point corresponding to these interactions. 相似文献
838.
Dr. María José García-Jiménez Dr. Sergio Gil-Caballero Dr. Susana Maza Dr. Francisco Corzana Dr. Francisco Juárez-Vicente Jonathan R. Miles Dr. Kazuma Sakamoto Prof. Kenji Kadomatsu Dr. Mario García-Domínguez Dr. José L. de Paz Dr. Pedro M. Nieto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(48):12395-12409
Midkine (MK) is a neurotrophic factor that participates in the embryonic central nervous system (CNS) development and neural stem cell regulation, interacting with sulfated glycosaminoglycans (GAGs). Chondroitin sulfate (CS) is the natural ligand in the CNS. In this work, we describe the interactions between a library of synthetic models of CS-types and mimics. We did a structural study of this library by NMR and MD (Molecular Dynamics), concluding that the basic shape is controlled by similar geometry of the glycosidic linkages. Their 3D structures are a helix with four residues per turn, almost linear. We have studied the tetrasaccharide-midkine complexes by ligand observed NMR techniques and concluded that the shape of the ligands does not change upon binding. The ligand orientation into the complex is very variable. It is placed inside the central cavity of MK formed by the two structured beta-sheets domains linked by an intrinsically disordered region (IDR). Docking analysis confirmed the participation of aromatics residues from MK completed with electrostatic interactions. Finally, we test the biological activity by increasing the MK expression using CS tetrasaccharides and their capacity in enhancing the growth stimulation effect of MK in NIH3T3 cells. 相似文献
839.
Susana Estopiñá-Durán Dr. James E. Taylor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(1):106-120
The direct, catalytic dehydrative substitution of alcohols is a challenging, yet highly desirable process in the development of more sustainable approaches to organic chemistry. This review outlines recent advances in Brønsted acid-catalysed dehydrative substitution reactions for C−C, C−O, C−N and C−S bond formation. The wide range of processes that are now accessible using simple alcohols as the formal electrophile are highlighted, while current limitations and therefore possible future directions for research are also discussed. 相似文献
840.
Florian Emmerich Stefan Zschiedrich Christine Reichenbach-Braun Caner Süsal Susana Minguet Marie-Christin Pauly Maximilian Seidl 《Molecules (Basel, Switzerland)》2021,26(9)
Acute and chronic transplant rejections due to alloreactivity are essential contributors to graft loss. However, the strength of alloreactivity is biased by non-immunological factors such as ischemia reperfusion injury (IRI). Accordingly, protection from IRI could be favorable in terms of limiting graft rejection. Caveolin-1 (Cav-1) is part of the cell membrane and an important regulator of intracellular signaling. Cav-1 has been demonstrated to limit IRI and to promote the survival of a variety of cell types including renal cells under stress conditions. Accordingly, Cav-1 could also play a role in limiting anti-graft immune responses. Here, we evaluated a possible association between pre-transplant serum concentrations of Cav-1 and the occurrence of rejection during follow-up in a pilot study. Therefore, Cav-1-serum concentrations were analyzed in 91 patients at the time of kidney transplantation and compared to the incidence of acute and chronic rejection. Higher Cav-1 levels were associated with lower occurrence of acute cellular tubulointerstitial rejection episodes. 相似文献