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821.
The inhibition of β-secretase (BACE1) is currently the main pharmacological strategy available for Alzheimer’s disease (AD). 2D QSAR and 3D QSAR analysis on some cyclic sulfone hydroxyethylamines inhibitors against β-secretase (IC50: 0.002–2.75 μM) were carried out using hologram QSAR (HQSAR), comparative molecular field analysis (CoMFA), and comparative molecular similarity indices analysis (CoMSIA) methods. The best model based on the training set was generated with a HQSAR q2 value of 0.693 and r2 value of 0.981; a CoMFA q2 value of 0.534 and r2 value of 0.913; and a CoMSIA q2 value of 0.512 and r2 value of 0.973. In order to gain further understand of the vital interactions between cyclic sulfone hydroxyethylamines and the protease, the analysis was performed by combining the CoMFA and CoMSIA field distributions with the active sites of the BACE1. The final QSAR models could be helpful in the design and development of novel active BACE1 inhibitors. 相似文献
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本文介绍了一种由STC12C2052AD型单片机控制,光敏传感器采集信号,继电器执行动作的夜间汽车前大灯远近灯光转换的自动控制系统。该系统安装在汽车上,使汽车在夜间行驶时,根据对头车驶近驶离的情况,能够自动调节前大灯远近灯光转换。该系统稳定可靠,成本低廉。有一定的推广和使用价值。 相似文献
825.
You‐Mei Bao Xiao‐Hui Liu Xiu‐Lan Tang Yue‐Sheng Li 《Journal of polymer science. Part A, Polymer chemistry》2010,48(23):5364-5374
A series of novel hyperbranched poly(ester‐amide)s (HBPEAs) based on neutral α‐amino acids have been synthesized via the “AD + CBB′” couple‐monomer approach. The ABB′ intermediates were stoichiometrically formed through thio‐Michael addition reaction because of reactivity differences between functional groups. Without any purification, in situ self‐polycondensations of the intermediates at elevated temperature in the presence of a catalyst afforded HBPEAs with multihydroxyl end groups. The degrees of branching (DBs) of the HBPEAs were estimated to be 0.40–0.58 and 0.24–0.54 by quantitative 13C NMR with two different calculation methods, respectively, depending on polymerization conditions and structure of monomers. The influences of catalyst, temperature, and intermediate structure on the polymerization process and molecular weights as well as properties of the resultant polymers were investigated. FTIR, NMR, and DEPT‐135 NMR analyses revealed the branched structure of the resultant polymers. The HBPEAs possess moderately high molecular weights with broad distributions, glass transition temperatures in the range of ?25.5 to 36.5 °C, and decomposition temperatures at 10% weight loss under nitrogen and air in the regions of 243.4–289.1 °C and 231.4–265.6 °C, respectively. Among them, those derived from D ,L ‐phenylalanine display the lowest degree of branching, whereas the highest glass transition temperature and the best thermal stability. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
826.
Min Li Zongbi Bao Baogen Su Huabin Xing Yiwen Yang Qilong Ren 《Journal of separation science》2013,36(18):3093-3100
The chiral separation of citalopram base by supercritical fluid chromatography on a semipreparative Chiralpak AD column was studied with the use of three alcohol‐type modifiers (methanol, ethanol, and 2‐propanol) with different volume percentages (5, 10, and 15%). The best separation was achieved when 10% 2‐propanol was used in the presence of 0.1% diethylamine as additive. Under these conditions, the resolution reached 2.15 and the selectivity was 1.388. In addition, other parameters that affected the retention and separation properties, i.e. temperature, pressure, and density, were studied in detail. At the same pressure, a decrease in the temperature improved the enantioselectivity as the experimental temperature range was below the isoelution temperature. However, the temperature dependence of the retention factor was complicated. As a rule, the retention factor decreased when the temperature increased at the same density. A satisfactory regression of the logarithm of the retention factor versus density and temperature was obtained using a simplified lattice‐fluid model. Surprisingly, the relationship between the Henry constant and density can be accurately correlated by using the same quadratic equation. 相似文献
827.
结合AD9142在GSM无线通信发射机中的应用,指出了边带信号对系统性能的影响,着重从原理上分析了接口时序错误对边带信号的贡献、成因及改善方法,并给出了时序优化前后的数据对比验证结果。为了保证DAC输出性能达到最优,需要保证接口时序满足建立时间和保持时间要求。通过调整基带处理侧的延时和DAC内部的延时可以使接口时序满足要求。 相似文献
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Galina F. Makhaeva Nadezhda V. Kovaleva Natalia P. Boltneva Elena V. Rudakova Sofya V. Lushchekina Tatiana Yu. Astakhova Igor V. Serkov Alexey N. Proshin Eugene V. Radchenko Vladimir A. Palyulin Jan Korabecny Ondrej Soukup Sergey O. Bachurin Rudy J. Richardson 《Molecules (Basel, Switzerland)》2022,27(3)
Using two ways of functionalizing amiridine—acylation with chloroacetic acid chloride and reaction with thiophosgene—we have synthesized new homobivalent bis-amiridines joined by two different spacers—bis-N-acyl-alkylene (3) and bis-N-thiourea-alkylene (5) —as potential multifunctional agents for the treatment of Alzheimer’s disease (AD). All compounds exhibited high inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with selectivity for BChE. These new agents displayed negligible carboxylesterase inhibition, suggesting a probable lack of untoward drug–drug interactions arising from hydrolytic biotransformation. Compounds 3 with bis-N-acyl-alkylene spacers were more potent inhibitors of both cholinesterases compared to compounds 5 and the parent amiridine. The lead compounds 3a–c exhibited an IC50(AChE) = 2.9–1.4 µM, IC50(BChE) = 0.13–0.067 µM, and 14–18% propidium displacement at 20 μM. Kinetic studies of compounds 3a and 5d indicated mixed-type reversible inhibition. Molecular docking revealed favorable poses in both catalytic and peripheral AChE sites. Propidium displacement from the peripheral site by the hybrids suggests their potential to hinder AChE-assisted Aβ42 aggregation. Conjugates 3 had no effect on Aβ42 self-aggregation, whereas compounds 5c–e (m = 4, 5, 6) showed mild (13–17%) inhibition. The greatest difference between conjugates 3 and 5 was their antioxidant activity. Bis-amiridines 3 with N-acylalkylene spacers were nearly inactive in ABTS and FRAP tests, whereas compounds 5 with thiourea in the spacers demonstrated high antioxidant activity, especially in the ABTS test (TEAC = 1.2–2.1), in agreement with their significantly lower HOMO-LUMO gap values. Calculated ADMET parameters for all conjugates predicted favorable blood–brain barrier permeability and intestinal absorption, as well as a low propensity for cardiac toxicity. Thus, it was possible to obtain amiridine derivatives whose potencies against AChE and BChE equaled (5) or exceeded (3) that of the parent compound, amiridine. Overall, based on their expanded and balanced pharmacological profiles, conjugates 5c–e appear promising for future optimization and development as multitarget anti-AD agents. 相似文献