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991.
Minematsu T Felder L Oppeneer T Sakazume M Oikawa K Hashimoto T Usui T Kamimura H 《Biomedical chromatography : BMC》2008,22(7):763-769
This paper describes a sensitive and selective liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for determination of the novel survivin suppressant YM155, 1-(2-methoxyethyl)-2-methyl-4,9-dioxo-3-(pyrazin-2-ylmethyl)-4,9-dihydro-1H-naphtho[2,3-d]imidazolium, which is developed for the treatment of solid tumors. This method uses a liquid-liquid extraction from 0.25 mL of dog plasma. LC separation was carried out on a Genesis Silica column (50 mm x 3.0 mm i.d.) at a flow-rate of 0.5 mL/min. Compounds were eluted using a mobile phase of 5 mm ammonium acetate and 0.1% formic acid in water-0.1% formic acid in acetonitrile, 17:83 (v/v). MS/MS detection was carried out with an MDS-Sciex API3000 triple quadrupole mass spectrometer in positive electrospray ionization mode. The standard curve was linear from 0.05 to 50 ng/mL (r > or = 0.9968). The lower limit of quantitation was 0.05 ng/mL. Good intra- and inter-day assay precision (within 7.4% RSD) and accuracy (within +/-12.3%) were obtained. The extraction recovery was 66.2%. The method was successfully applied to preclinical pharmacokinetic studies in dogs. 相似文献
992.
Thermally assisted base-catalyzed rearrangement of furo[2,3-c]quinoline-2,4(3aH,5H)-diones 1 to the corresponding furo[3,4-c]quinoline-3,4(1H,5H)-diones 2 is reported, and a mechanism of the transformation is proposed. 相似文献
993.
Joerg Harloff 《Journal of organometallic chemistry》2008,693(7):1283-1291
The reaction pathway for the formation of the trimethylsiloxysilyllithium compounds (Me3SiO)RR′SiLi (2a: R = Et, 2b: R = iPr, 2c: R = 2,4,6-Me3C6H2 (Mes); 2a-c: R′ = Ph; 2d: R = R′ = Mes) starting from the conversion of the corresponding trimethylsiloxychlorosilanes (Me3SiO)RR′SiCl (1a-d) in the presence of excess lithium in a mixture of THF/diethyl ether/n-pentane at −110 °C was investigated.The trimethylsiloxychlorosilanes (Me3SiO)RPhSiCl (1a: R = Et, 1b: R = iPr, 1c: R = Mes) react with lithium to give initially the trimethylsiloxysilyllithium compounds (Me3SiO)RPhSiLi (2a-c). These siloxysilyllithiums 2 couple partially with more trimethylsiloxychlorosilanes 1 to produce the siloxydisilanes (Me3SiO)RPhSi-SiPhR(OSiMe3) (Ia-c), and they undergo bimolecular self-condensation affording the trimethylsiloxydisilanyllithium compounds (Me3SiO)RPhSi-RPhSiLi (3a-c). The siloxydisilanes I are cleaved by excess of lithium to give the trimethylsiloxysilyllithiums (Me3SiO)RPhSiLi (2). In the case of the two trimethylsiloxydisilanyllithiums (Me3SiO)RPhSi-RPhSiLi (3a: R = Et, 3b: R = iPr) a reaction with more trimethylsiloxychlorosilanes (Me3SiO)RPhSiCl (1a, 1b) takes place under formation of siloxytrisilanes (Me3SiO)RPhSi-RPhSi-SiPhR(OSiMe3) (IIa: R = Et, IIb: R = iPr) which are cleaved by lithium to yield the trimethylsiloxysilyllithiums (Me3SiO)RPhSiLi (2a, 2b) and the trimethylsiloxydisilanyllithiums (Me3SiO)RPhSi-RPhSiLi (3a, 3b). The dimesityl-trimethylsiloxy-silyllithium (Me3SiO)Mes2SiLi (2d) was obtained directly by reaction of the trimethylsiloxychlorosilane (Me3SiO)Mes2SiCl (1d) and lithium without formation of the siloxydisilane intermediate. Both silyllithium compounds 2 and 3 were trapped with HMe2SiCl giving the products (Me3SiO)RR′Si-SiMe2H and (Me3SiO)RPhSi-RPhSi-SiMe2H. 相似文献
994.
Mirna M. Heredia R. M. Loroo Tania Crdova Gabriel Chuchani 《Journal of Molecular Structure》2006,770(1-3):131-137
The theoretical studies of the gas-phase elimination of 2-substituted ethyl N,N-dimethylcarbamates (Z=CH2Cl, C≡CH, C≡N) were performed using ab initio MP2/6-31G and MP2/6-31G(d) levels of theory. The gas phase elimination reaction of these carbamates yields N,N-dimethylcarbamic acid and the corresponding substituted olefin in a rate-determining step. The intermediate N,N-dimethylcarbamic acid is unstable and rapidly decomposes through a four-membered cyclic transition state to dimethylamine and CO2 gas. The results of these calculations suggest a mechanism to be concerted, asynchronous, and a six-membered cyclic transition state structure. Plotting the relative theoretical rate coefficients against Taft's σ* values gave an approximate straight line (ρ*=0.4057, r=0.9894 at 360 °C). The correlation between experimental log krel vs. theoretical log krel. for these 2-substituted ethyl N,N-dimethylcarbamates gave an approximate straight line (r=0.9715 at 360 °C), suggesting the same type of mechanism. 相似文献
995.
本文采用DFT和TD-DFT方法研究了Keggin型多酸[SiW12O40]4-光催化劈裂水产氢气机理。计算结果显示反应主要包括四个步骤:(i) 光激发,(ii) 电荷转移和生成单电子还原(OER)中间体,(iii) 生成双电子还原(TER)中间体,(iv)氢气从多酸表面解离和催化剂重生。当第一个电子从甲醇转移到多酸后,后续反应存在均为热力学上有利的放热途径,并推动第二个电子从甲醇自由基,H[SiW12O40]4-或[SiW12O40]5-转移到OER中间体H[SiW12O40]4-或[SiW12O40]5-生成TER中间体[SiW12O40]6-,H[SiW12O40]5-或H2[SiW12O40]4-,并伴随着H2产生。耦合的电子和质子转移路径在能量上最有利。甲醇和水分子的参与有利于H2产生。多酸在整个催化循环中,扮演了光敏剂、催化剂、电子的受体和给体。 相似文献
996.
Raffaella Pascale Giuliana Bianco Donatella Coviello Maria Cristina Lafiosca Salvatore Masi Ignazio M. Mancini Sabino A. Bufo Laura Scrano Donatella Caniani 《Journal of separation science》2020,43(5):886-895
Pharmaceuticals constitute one of the most important emerging classes of environmental pollutants. A three‐phase solvent system of water, water containing 0.1% of formic acid and acetonitrile was successfully used to separate, by liquid chromatography with mass spectrometry (LC‐MS), polarity‐matched pharmaceuticals, that is, carbamazepine, clarithromycin, and erythromycin, as well as amoxicillin and metformin. Despite of polarity similarities, these pharmaceuticals were completely resolved in the analytical run time of 15 min. The optimized three‐phase solvent system based‐method was validated for the simultaneous analysis of six matched‐polarity pharmaceuticals in wastewater samples. Good linearity (coefficient of determination more than 0.993) and precision (relative standard deviation less than 15.66%) were achieved. Recovery of analytes from the wastewater was between 0.70 and 1.18. Limits of detections ranged from 0.0001 to 0.5114 µg/L. No significant matrix effect, evaluated by post extraction addition, was observed in the electrospray ionization (ESI) source. Then, this methodology has been successfully applied to environmental study of pharmaceutical residues occurring in influent and effluent wastewater samples, from the main wastewater treatment plant in Potenza (Basilicata, Southern Italy). 相似文献
997.
Metal‐organic frameworks (MOFs) as new classes of proton‐conducting materials have been highlighted in recent years. Nevertheless, the exploration of proton‐conducting MOFs as formic acid sensors is extremely lacking. Herein, we prepared two highly stable 3D isostructural lanthanide(III) MOFs, {(M(μ3‐HPhIDC)(μ2‐C2O4)0.5(H2O))?2 H2O}n (M=Tb ( ZZU‐1 ); Eu ( ZZU‐2 )) (H3PhIDC=2‐phenyl‐1H‐imidazole‐4,5‐dicarboxylic acid), in which the coordinated and uncoordinated water molecules and uncoordinated imidazole N atoms play decisive roles for the high‐performance proton conduction and recognition ability for formic acid. Both ZZU‐1 and ZZU‐2 show temperature‐ and humidity‐dependent proton‐conducting characteristics with high conductivities of 8.95×10?4 and 4.63×10?4 S cm‐1 at 98 % RH and 100 °C, respectively. Importantly, the impedance values of the two MOF‐based sensors decrease upon exposure to formic acid vapor generated from formic aqueous solutions at 25 °C with good reproducibility. By comparing the changes of impedance values, we can indirectly determine the concentration of HCOOH in aqueous solution. The results showed that the lowest detectable concentrations of formic acid aqueous solutions are 1.2×10?2 mol L?1 by ZZU‐1 and 2.0×10?2 mol L?1 by ZZU‐2 . Furthermore, the two sensors can distinguish formic acid vapor from interfering vapors including MeOH, N‐hexane, benzene, toluene, EtOH, acetone, acetic acid and butane. Our research provides a new platform of proton‐conductive MOFs‐based sensors for detecting formic acid. 相似文献
998.
自1978年顺铂成功地被开发成癌症临床治疗药物以来,金属配合物作为小分子抗癌药物的开发成为人们的研究热点。其中,氮杂环卡宾能与多种过渡金属中心形成稳定的共价键,这种特殊的稳定性使得金属氮杂环卡宾配合物具有被开发成药物的潜能。近年来,金属氮杂环卡宾配合物被发现具有良好的抗癌活性,激发了广大无机药物化学研究者的研究热情。综合笔者课题组在金属氮杂环卡宾抗肿瘤配合物方面的前期研究,本文将对银、金、铑和铂氮杂环卡宾配合物的抗肿瘤活性及作用机制进行综述,以期为新型金属氮杂环卡宾抗肿瘤化合物的设计合成提供参考。 相似文献
999.
Mariana Millan Fachi Raquel Oliveira Vilhena Beatriz Boger Eric Luiz Domingos Josiane Marlei Müller Fernandes dos Santos Allan Michael Junkert Alexandre de Fátima Cobre Danilo Raul Ossufo Momade Francisco Beraldi-Magalhães Marcus Vinicius de Liz Marcelo Cordeiro-Santos Roberto Pontarolo 《Biomedical chromatography : BMC》2020,34(5):e4812
In this research, we developed and validated a liquid chromatography coupled to mass spectrometry (LC–QToF–MS) method for simultaneous quantification of the anti-tuberculosis drugs ethambutol, isoniazid, pyrazinamide and rifampicin in human plasma. Plasma samples spiked with cimetidine (internal standard) were extracted using protein precipitation with acetonitrile containing 1% formic acid. Separation was performed using a C18 column under flow gradient conditions with water and acetonitrile, both containing 5 mm ammonium formate and 0.1% formic acid. The method was validated according to the ANVISA and US Food and Drug Administration guidelines for bioanalytical method validation. The calibration curve was linear over a concentration range of 0.2–5 μg ml−1 for ethambutol, 0.2–7.5 μg ml−1 for isoniazid, 1–40 μg ml−1 for pyrazinamide and 0.25–2 μg ml−1 for rifampicin, all with adequate precision and accuracy. The method was reproducible, selective and free of carryover and matrix effects. The validated LC–QToF–MS method was successfully applied to real samples and shown to be applicable to future therapeutic and pharmacokinetic monitoring studies. 相似文献
1000.
Kiran R. Patil Vipul P. Rane Jaiprakash N. Sangshetti Devanand B. Shinde 《Chromatographia》2008,67(7-8):575-582
A simple, rapid, and precise method is developed for the quantitative simultaneous estimation of telmisartan and ramipril
in combined pharmaceutical dosage form. A chromatographic separation of the two drugs was achieved with an ACE 5 C18, 25-cm analytical column using buffer–acetonitrile (55:45 v/v). The buffer used in mobile phase contains 0.1 M sodium perchlorate monohydrate in double distilled water pH adjusted 3.0
with trifluoroacetic acid. The instrumental settings are flow rate of 1.5 mL min−1, column temperature at 30 °C, and detector wavelength of 215 nm using a photodiode array detector. The resolution between
ramipril and telmisartan were found to be more than 5. Theoretical plates for ramipril and telmisartan were 13,022 and 6,629.
Tailing factor for ramipril and telmisartan was 0.94 and 0.98. Telmisartan, ramipril and their combination drug product were
exposed to thermal, photolytic, hydrolytic and oxidative stress conditions, and the stressed samples were analysed by the
proposed method. Peak homogeneity data of telmisartan and ramipril is obtained using photodiode array detector, in the stressed
sample chromatograms, demonstrated the specificity of the method for their estimation in presence of degradants. The described
method shows excellent linearity over a range of 20–400 μg mL−1 for telmisartan and 2.5–50 μg mL−1 for ramipril. The correlation coefficient for telmisartan and ramipril are 1. The relative standard deviation for six measurements
in two sets of each drug in tablets was always less than 2%. The proposed method was found to be suitable and accurate for
quantitative determination and the stability study of telmisartan and ramipril in pharmaceutical preparations. 相似文献