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971.
Rita F. Cunha Sandra Simes Manuela Carvalheiro Jos M. Azevedo Pereira Quirina Costa Andreia Ascenso 《Molecules (Basel, Switzerland)》2021,26(17)
When the first cases of HIV infection appeared in the 1980s, AIDS was a deadly disease without any therapeutic alternatives. Currently, there is still no cure for most cases mainly due to the multiple tissues that act as a reservoir for this virus besides the high viral mutagenesis that leads to an antiretroviral drug resistance. Throughout the years, multiple drugs with specific mechanisms of action on distinct targets have been approved. In this review, the most recent phase III clinical studies and other research therapies as advanced antiretroviral nanodelivery systems will be here discussed. Although the combined antiretroviral therapy is effective in reducing viral loading to undetectable levels, it also presents some disadvantages, such as usual side effects, high frequency of administration, and the possibility of drug resistance. Therefore, several new drugs, delivery systems, and vaccines have been tested in pre-clinical and clinical trials. Regarding drug delivery, an attempt to change the route of administration of some conventional antiretrovirals has proven to be successful and surpassed some issues related to patient compliance. Nanotechnology has brought a new approach to overcoming certain obstacles of formulation design including drug solubility and biodistribution. Overall, the encapsulation of antiretroviral drugs into nanosystems has shown improved drug release and pharmacokinetic profile. 相似文献
972.
In many realizations of electron spin qubits the dominant source of decoherence is the fluctuating nuclear spin bath of the host material. The slowness of this bath lends itself to a promising mitigation strategy where the nuclear spin bath is prepared in a narrowed state with suppressed fluctuations. Here, this approach is realized for a two-electron spin qubit in a GaAs double quantum dot and a nearly tenfold increase in the inhomogeneous dephasing time T?* is demonstrated. Between subsequent measurements, the bath is prepared by using the qubit as a feedback loop that first measures its nuclear environment by coherent precession, and then polarizes it depending on the final state. This procedure results in a stable fixed point at a nonzero polarization gradient between the two dots, which enables fast universal qubit control. 相似文献
973.
Fielding AJ Fox S Millhauser GL Chattopadhyay M Kroneck PM Fritz G Eaton GR Eaton SS 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2006,179(1):92-104
The temperature dependence, between 10 and 120 K, of electron spin-lattice relaxation at X-band was analyzed for a series of eight pyrrolate-imine complexes and for ten other copper(II) complexes with varying ligands and geometry including copper-containing prion octarepeat domain and S100 type proteins. The geometry of the CuN4 coordination sphere for pyrrolate-imine complexes with R=H, methyl, n-butyl, diphenylmethyl, benzyl, 2-adamantyl, 1-adamantyl, and tert-butyl has been shown to range from planar to pseudo-tetrahedral. The fit to the recovery curves was better for a distribution of values of T1 than for a single time constant. Distributions of relaxation times may be characteristic of Cu(II) in glassy solution. Long-pulse saturation recovery and inversion recovery measurements were performed. The temperature dependence of spin-lattice relaxation rates was analyzed in terms of contributions from the direct process, the Raman process, and local modes. It was necessary to include more than one process to fit the experimental data. There was a small contribution from the direct process at low temperature. The Raman process was the dominant contribution to relaxation between about 20 and 60 K. Debye temperatures were between 80 and 120 K. For samples with similar Debye temperatures the coefficient of the Raman process tended to increase as gz increased, as expected if modulation of spin-orbit coupling is a major factor in relaxation rates. Above about 60 K local modes with energies in the range of 260-360 K (180-250 cm-1) dominated the relaxation. For molecules with similar geometry, relaxation rates were faster for more flexible molecules than for more rigid ones. Relaxation rates for the copper protein samples were similar to rates for small molecules with comparable coordination spheres. At each temperature studied the range of relaxation rates was less than an order of magnitude. The spread was smaller between 20 and 60 K where the Raman process dominates, than at higher temperatures where local modes dominate the relaxation. Spin echo dephasing time constants, Tm, were calculated from two-pulse spin echo decays. Near 10 K Tm was dominated by proton spins in the surroundings. As temperature was increased motion and spin-lattice relaxation made increasing contributions to Tm. Near 100 K spin-lattice relaxation dominated Tm. 相似文献
974.
Molecular recognition properties of acyclic cucurbiturils toward amino acids,peptides, and a protein
Sandra A. Zebaze Ndendjio 《Supramolecular chemistry》2019,31(7):432-441
The binding of 1 and 2 toward 19 amino acid amides by 1H NMR and ITC is reported. Hosts 1 and 2 bind to aromatic or hydrophobic residues by cavity inclusion leaving the cationic residues at the C=O portals. Ka values range from 102 to >106 M?1 with H-Phe-NH2, H-Trp-NH2, and H-Tyr-NH2 displaying sub-micromolar Kd values. Hosts 1 and 2 bind tightly to dicationic H-Lys-NH2 and H-Arg-NH2 which are poor guests for CB[7]. Comparison of the affinity of 1 and 2 toward the amino acid amide, N-acetyl-amino-acid amide, and amino acid forms of Phe revealed that the removal of the NH3+ to O=C and SO3? electrostatic interactions costs 3.8 kcal/mol whereas the introduction of an unfavourable CO2? to O=C and SO3? electrostatic interactions costs 2.1 kcal/mol. Hosts 1 and 2 bind to insulin with low micromolar affinity. Acyclic CB[n] display high affinity toward a wider range of N-terminal amino acids residues than CB[n] which suggests a broad range of applications. 相似文献
975.
Bryan T. Tuten Lies DeKeer Sandra Wiedbrauk Paul H. M. VanSteenberge Dagmar R. D'hooge Christopher Barner‐Kowollik 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(17):5728-5732
Herein, we introduce an additive‐free visible‐light‐induced Passerini multicomponent polymerization (MCP) for the generation of high molar mass chains. In place of classical aldehydes (or ketones), highly reactive, in situ photogenerated thioaldehydes are exploited along with isocyanides and carboxylic acids. Prone to side reactions, the thioaldehyde moieties create a complex reaction environment which can be tamed by optimizing the synthetic conditions utilizing stochastic reaction path analysis, highlighting the potential of semi‐batch procedures. Once the complex MCP environment is understood, step‐growth polymers can be synthesized under mild reaction conditions which—after a Mumm rearrangement—result in the incorporation of thioester moieties directly into the polymer backbone, leading to soft matter materials that can be degraded by straightforward aminolysis or chain expanded by thiirane insertion. 相似文献
976.
Lucas Andreo Carla A. Soldera Beatriz Guimares Ribeiro Patrick Raoul Vicente de Matos Paola Bindes Sousa Weslley Wallace de Alcntara Araújo Amorim Anna Carolina Ratto Tempestini Horliana Sandra Kalil Bussadori Kristianne Porta Santos Fernandes Raquel Agnelli Mesquita‐Ferrari 《Photochemistry and photobiology》2019,95(3):879-885
A peripheral nerve injury (PNI) can result in motor or sensory disorders. Low‐level laser therapy (LLLT) has demonstrated positive results as a treatment option for PNI. Wistar rats were divided into five groups: Control, Injury, Injury + LLLTn (nerve), Injury + LLLTm (muscle) and Injury + LLLTn + m (nerve and muscle irradiation). The groups were analyzed after one, two, three and four weeks. PNI was achieved by crushing the sciatic nerve. Laser treatment (780 nm, 3.2 J) was realized over the nerve and/or tibialis anterior muscle. In gait analyses, the groups irradiated over the nerve demonstrated an improvement after two weeks. In the analysis of mechanical sensitivity, the Injury + LLLTn demonstrated a reduction after one week in comparison with Injury group; the Injury + LLLTn + m and Injury + LLLTm demonstrated an increase after two weeks in comparison with Injury group; and the irradiated groups demonstrated a reduction in nociception after four weeks in comparison with Injury group. In the analysis of muscle atrophy, the Injury + LLLTn demonstrated more muscle mass after two weeks. LLLT improves functional aspects related to gait, mechanical sensitivity and muscle mass, with better results regarding motor aspects and muscle mass when administered over the injured nerve and better results regarding sensory aspects when administered over the muscle. 相似文献
977.
Gaoxiang Liu Zhaoguo Zhu Sandra M. Ciborowski Isuru R. Ariyarathna Evangelos Miliordos Kit H. Bowen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(23):7855-7859
Mass spectrometric analysis of the anionic products of interaction between platinum atomic anions, Pt?, and methane, CH4 and CD4, in a collision cell shows the preferred generation of [PtCH4]? and [PtCD4]? complexes and a low tendency toward dehydrogenation. [PtCH4]? is shown to be H?Pt?CH3? by a synergy between anion photoelectron spectroscopy and quantum chemical calculations, implying the rupture of a single C?H bond. The calculated reaction pathway accounts for the observed selective activation of methane by Pt?. This study presents the first example of methane activation by a single atomic anion. 相似文献
978.
Sandra S. Nurttila Dr. Wolfgang Brenner Dr. Jesús Mosquera Kaj M. van Vliet Prof. Dr. Jonathan R. Nitschke Prof. Dr. Joost N. H. Reek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(2):609-620
Size-selective hydroformylation of terminal alkenes was attained upon embedding a rhodium bisphosphine complex in a supramolecular metal–organic cage that was formed by subcomponent self-assembly. The catalyst was bound in the cage by a ligand-template approach, in which pyridyl–zinc(II) porphyrin interactions led to high association constants (>105 m −1) for the binding of the ligands and the corresponding rhodium complex. DFT calculations confirm that the second coordination sphere forces the encapsulated active species to adopt the ee coordination geometry (i.e., both phosphine ligands in equatorial positions), in line with in situ high-pressure IR studies of the host–guest complex. The window aperture of the cage decreases slightly upon binding the catalyst. As a result, the diffusion of larger substrates into the cage is slower compared to that of smaller substrates. Consequently, the encapsulated rhodium catalyst displays substrate selectivity, converting smaller substrates faster to the corresponding aldehydes. This selectivity bears a resemblance to an effect observed in nature, where enzymes are able to discriminate between substrates based on shape and size by embedding the active site deep inside the hydrophobic pocket of a bulky protein structure. 相似文献
979.
Iman Taraghi Abdolhossein Fereidoon Sandra Paszkiewicz Zbigniew Roslaniec 《Composite Interfaces》2018,25(3):275-286
In this article, the phase separation in the melt blended polycarbonate (PC) and ethylene propylene copolymer (EPC) has been studied with dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM). Two glass transition temperatures on the tan δ curves were detected. This confirms the immiscibility of PC and EPC phases. Different content of multi-walled carbon nanotubes (MWCNTs) were added to the PC/EPC blends and the interfacial adhesion between MWCNTs and PC/EPC blend were shown using transmission electron microscopy (TEM). The MWCNTs were located in the PC phase and at the interfaces of PC and EPC phases. Moreover, the storage modulus (E′) of polymer blends was changed by the increasing content of EPC elastomer and MWCNTs. The value of E′ of PC decreased with an incorporation of EPC. While, along with an addition of MWCNTs in the PC/EPC blends an increase of E′ was visible. The strong interfacial interactions between the matrix and MWCNTs played the main role in increasing the values of the E′ of the nanocomposites. 相似文献
980.
Sandra Piras Gabriele Murineddu Giovanni Loriga Antonio Carta Enrica Battistello Stefania Merighi Stefania Gessi Paola Corona Battistina Asproni Roberta Ibba Veronika Temml Daniela Schuster Grard Aim Pinna 《Molecules (Basel, Switzerland)》2021,26(18)
Opioid analgesics are clinically used to relieve severe pain in acute postoperative and cancer pain, and also in the long term in chronic pain. The analgesic action is mediated by μ-, δ-, and κ-receptors, but currently, with few exceptions for k-agonists, μ-agonists are the only ones used in therapy. Previously synthesized compounds with diazotricyclodecane cores (DTDs) have shown their effectiveness in binding opioid receptors. Fourteen novel diazatricyclodecanes belonging to the 9-propionyl-10-substituted-9,10-diazatricyclo[4.2.1.12,5]decane (compounds 20–23, 53, 57 and 59) and 2-propionyl-7-substituted-2,7-diazatricyclo[4.4.0.03,8]decane (compounds 24–27, 54, 58 and 60) series, respectively, have been synthesized and their ability to bind to the opioid μ-, δ- and κ-receptors was evaluated. Five of these derivatives, compounds 20, 21, 24, 26 and 53, showed μ-affinity in the nanomolar range with a negligible affinity towards δ- and κ-receptors and high μ-receptor selectivity. The synthesized compounds showed μ-receptor selectivity higher than those of previously reported methylarylcinnamyl analogs. 相似文献