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11.
Electrocatalytic oxidation of thiosulfate on a modified nickel hexacyanoferrate film electrode 总被引:1,自引:0,他引:1
Xingyao Zhou Shengfu Wang Zhengpin Wang Mian Jiang 《Fresenius' Journal of Analytical Chemistry》1993,345(6):424-427
Summary A modified nickel hexacyanoferrate film glassy carbon electrode is prepared by the electrochemical deposition technique. The film is very stable upon voltammetric scanning in the potential range of 1.0 to –0.5 V (vs. SCE) and an oxidation peak occurs at 0.35 V (vs. SCE) (1 mol/l NaNO3). The effects of electrolyte, solvent, coexisting ions and other variables on the voltammetric behaviour of the modified film have been studied. The thickness of the resulting film can be controlled by changing the number of voltammetric cycles and the concentrations of nickel(II) and hexacyanoferrate(III) ions. The film shows catalytic activity towards electrooxidation of thiosulfate with a peak potential +0.5 V (K–-containing media). This oxidation potential of thiosulfate on the modified electrode is shifted negatively by about 550 mV as compared to the naked glassy carbon electrode. For practical application, the modified electrode can be used for the determination of thiosulfate in concentrations from 5.0×10–5 to 1.0×10–1 mol/l. This method has been successfully applied to the determination of thiosulfate in photographic waste effluents. 相似文献
12.
Mian Chin Gregory L. Durst Simone R. Head Paul L. BockJohn A. Mosbo 《Journal of organometallic chemistry》1994,470(1-2):73-85
Molecular mechanics (MM2) calculations were performed on 54 conformations of 18 phosphines (PH3; PH3−nRn, where n = 1,…3, and R = Me and Et, n = 1 or 2 and R =iPr, and n = 1 and R =tBu, PMe2Et, PMeEt2, and PPhMe2, and PPh2R where R = Me, Et, iPr, tBu and Ph). The results are compared to those previously obtained from MINDO/3 and MNDO calculations, and to experimental data. Single conformer cone angles and weighted average cone angles were calculated from MM2 optimized geometries employing Tolman's general definition, and they are compared to Tolman's values, MINDO/3 results, and T.L. Brown's ER values. Of the cone angle definitions used, the weighted average values are suggested as the best single representation of phosphine ligand sizes. The steric parameters (cone angle and ER values) alone, and in conjunction with electronic parameters, are correlated with experimental data. 相似文献
13.
Mian Fu Xiaomei Zhuang Tianhong Zhang Ying Guan Qingbin Meng Yongjun Zhang 《Macromolecular bioscience》2020,20(9)
Leuprolide has been widely used in androgen deprivation therapy for the treatment of advanced prostate cancer, but its use is still limited due to its short half‐life. Herein, hydrogen‐bonded layer‐by‐layer films are fabricated from PEGylated leuprolide (PEG‐LEU) and tannic acid (TA). Because of its dynamic nature, the film disintegrates gradually in water and releases PEG‐LEU and TA. The in vitro release profile indicated perfect zero‐order kinetics, which is explained by the unique release mechanism. When implanted subcutaneously in male rats, the films maintain a constant serum drug level. For a 60‐bilayer film, the serum drug level is maintained constant for ≈24 days. No initial burst release is observed, suggesting that the in vivo release also follows zero‐order kinetics. Initially, an increase in the level of serum testosterone is induced by the released drug, followed by testosterone suppression to a constant level below the castrate level, which could be maintained as long as a constant serum drug level is maintained. Since the new drug carriers avoid an initial burst release of the drug and maintain a constant serum drug level and hence a constant serum testosterone level below the castrate level, these carriers are highly promising for androgen deprivation therapy. 相似文献
14.
Lan Yu Qi Wang Lu Dai Wei-Ying Li Rong Chen Mian HR Mahmood Hai-Yang Liu Chi-Kwong Chang 《中国化学快报》2013,24(6):447-449
Pseudo-first order reaction rate constants of 5,10,15-tris(pentafluorophenyl)corrole Mn(V)-oxo (F15CMn(V)-oxo),5,15-bis(pentafluorophenyl)-10-(phenyl)corrole Mn(V)-oxo(F10CMn(V)-oxo),5,15- bis(phenyl)-10-(pentafluorophenyl)corrole Mn(V)-oxo(F5CMn(V)-oxo) and 5,10,15-tris(phenyl)corrole Mn(V)-oxo(F0CMn(V)-oxo) with a series of alkene substrates in different solvents were determined by UV-vis spectroscopy.The results indicated that the oxygen atom transfer pathway between Mn(V)-oxo corrole and alkene is solvent-dependent. 相似文献
15.
Qiong Wu Hui Feng Dong‐Dong Guo Mian‐Shuai Yi Xing‐Han Wang Bo Jiang Shu‐Jiang Tu 《Journal of heterocyclic chemistry》2013,50(3):599-602
A green and highly efficient method for the synthesis of polyfunctionalized indoline‐spiro fused pyran derivatives has been established. This reaction was conducted by reacting readily available and inexpensive starting materials, such as isatins, cyclic‐1,3‐dicarbonyl compounds, and malononitrile in aqueous media without any catalysts under microwave irradiation. The present green synthesis shows fascinating properties such as the use of water as the reaction solution, concise one‐pot conditions, short reaction periods (8–14 min), and easy purifications. The synthesis could also set a good example to GAP (Group‐Assistant‐Purification) chemistry in which purification via chromatography can be avoided and the pure products can be easily acquired only by washing the crude products with 95% EtOH. 相似文献
16.
Seven new alkaloids, named as 1,9-epoxy-9a-hydroxystenine (1), tuberostemoline A (2), tuberostemoline B (3), tuberostemoninol C (4), oxotuberostemonine A (5), the mixture of bisdehydrotuberostemonine D (6), and bisdehydrotuberostemonine E (7), together with four known alkaloids neotuberostemonine (8), sessilifoline B (9), stemoxazolidinone F (10), and tuberostemoninol A (11), were isolated from the roots of Stemona tuberosa. The structures of 1–7 were elucidated through extensive spectroscopic analysis, and the relative configurations of 1–6 and 8 were further confirmed by X-ray crystallographic data. Compounds 8, 9 and the mixture of 6 & 7 exhibited potential acetylcholinesterase (AChE) inhibitory activities. 相似文献
17.
Xiao-Xu Ba Tian Gao Mian Yang Peng Jiang Feng-Lei Jiang Yi Liu 《Journal of solution chemistry》2020,49(1):100-116
As one of the newly emerged nanomaterials, graphene quantum dots (GQDs) have shown great application potential as tracking probes and drug carriers in biological areas. The GQDs synthesized via the nitric acid reflux method in this study turned out to quench the fluorescence of human serum albumin (HSA) and gamma globulin (γ-globulin) in two different functional ways. The fluorescence quenching effect of GQDs on HSA is a static pattern and the predominant interaction forces are hydrogen bonds and van der Waals forces. Distinct from HSA, the interaction between GQDs and γ-globulins belongs to dynamic quenching and is driven by electrostatic forces. Ultraviolet–visible (UV–vis) differential spectrometry and transient state fluorescence spectrometry were also utilized to further confirm their quenching types. Also, thermodynamics parameters, the enthalpy change (ΔH) and entropy change (ΔS) of reaction between GQDs and proteins were obtained through a series of calculations from the van’t Hoff equation. Furthermore, the effect of GQDs on the conformational structure of proteins was characterized by synchronous fluorescence spectra (SFS), three-dimensional (3D) fluorescence and circular dichroism (CD) spectra. In addition, the binding mechanism of GQDs with HSA and γ-globulins were proposed based on the obtained experimental results. The research on the reaction between GQDs with HSA and γ-globulins offers promising insight for the further application of nanomaterials in biomedical fields. 相似文献
18.
19.
通用型激光诱导荧光微流控芯片分析仪的研制与性能考察 总被引:5,自引:0,他引:5
设计和研制了一种通用型激光诱导荧光微流控芯片分析仪.检测部分按共聚焦检测原理设计,采用CCD(电荷耦合器件)监测通道,三维自动调节聚焦,发射波长滤光片可方便地更换以适应多种染料选择,能分别显示进样和分离通道2条电流-时间曲线.考察了该分析仪的检测灵敏度、检测极限和线性范围,显示了分析灵敏度高,检测限低和线性范围宽等特点,在自制注塑型PMMA塑料芯片上实现了φX174Haedi-gesTdNA片段的分离测定和烟叶act基因PCR产物的分析 相似文献
20.
为了获得边坡逐孔爆破最佳降振微差时间,以某个实际边坡逐孔微差爆破施工现场为原型,先利用ANSYS建立二维静态模型,借助有限元折减法确定自然状态下的潜在滑动面和静态安全系数;基于已确定的二维潜在滑动面重新建立同尺寸同性质的三维逐孔微差爆破动态模型,利用LS-DYAN进行动力分析,整个过程分别设置同排3个炮孔0、17、25、42和65 ms等5种不同孔间微差起爆方式;同时,对该施工现场进行排、孔间(25 ms,17 ms)、(25 ms,25 ms)、(25 ms,42 ms)、(25 ms,65 ms)等4种微差时间控制的等比例相似小炮测振实验。提取模拟结果中3个炮孔同时起爆时滑面单元的应力数值代入极限平衡法计算公式,绘制了冲击载荷作用下边坡稳定性系数曲线,通过对曲线的理论分析发现,最佳降振微差时间约为48 ms;而三维数值模拟和测振实验结果均显示,孔间微差时间取42 ms时降振效果较佳。这说明,边坡稳定性系数曲线给出的微差时间与模拟和实验结果较为接近,可为今后边坡逐孔微差爆破降振研究提供参考。 相似文献