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81.
A large improvement of the electrochemical capacitive detection of ssDNA and antigens by using ethylene-glycol alkanethiol monolayers has been recently demonstrated. Alkanethiol monolayers without ethylene-glycol functionalization do not show the required electrochemical stability. In this paper, we demonstrate that both phenomena are related to their morphological structure at nano-scale. Ethylene-glycol monolayers were compared with similar films without ethylene-glycol function. Capacitance measurements were used to verify the improved capacitance stability of the electrochemical interface. AFM images were used to investigate films packing and morphology at the nano-scale. This letter demonstrates that films without ethylene-glycol segment present deep grooves which are related to electrochemical instability while the improvement in case of ethylene-glycols is due to the absence of such a feature. 相似文献
82.
Kumar M Bhalla V Dhir A Babu JN 《Dalton transactions (Cambridge, England : 2003)》2010,39(42):10116-10121
Synthetic strategies are described to synthesize the calix[4]arene diamine 4 of partial cone (paco) conformation, which on condensation with 9-anthracene carbaldehyde forms the chemosensor 5 in paco conformation. The chemosensor 5 undergoes fluorescence enhancement in the presence of Ni(2+) ions. 相似文献
83.
New thiacalix[4]crown derivatives 4 and 5 of 1,3-alternate conformation possessing anthracene and quinoline moieties respectively were synthesised and examined for their cation recognition abilities toward different cations by fluorescence spectroscopy. Selective optical recognition with fluorescence amplification was observed for Fe(3+)/K(+) and Hg(2+)/K(+) in chemosensors 4 and 5 respectively. Further it was observed that the formation of 4·Fe(3+) complex triggers the decomplexation of K(+) ion. Similar allosteric behaviour between Hg(2+) and K(+) was observed in chemosensor 5. 相似文献
84.
A new terphenyl based chemosensor 3 has been designed and synthesized. The binding behavior of 3 and its chemosensing ensemble 3-Hg toward various anions (F(-), Cl(-), Br(-), I(-), HSO(4)(-), H(2)PO(4)(-), CH(3)COO(-), NO(3)(-), N(3)(-), SO(4)(2-), SO(3)(2-), and Cr(2)O(7)(2-)) has been investigated by UV-Vis, fluorescence and NMR spectroscopy. Compound 3 shows a sensitivity for both F(-) and CH(3)COO(-) ions among various anions tested, whereas the ensemble 3-Hg shows a better selectivity for CH(3)COO(-) ions. The ensemble is utilized for CH(3)COO(-) recognition in a blood plasma like system. 相似文献
85.
Zinc ensemble of hexaphenylbenzene derivative 3 exhibits sensitive response toward adenosine monophosphate (AMP) and H(2)PO(4)(-) ions. Further, the application of derivative 3 as a multichannel molecular keypad could be realized in the presence of inputs of Zn(2+) ions, H(2)PO(4)(-) ions, and AMP. 相似文献
86.
87.
Photosynthetic bacterial reaction centers (BRC) have shown great potential for bioengineering applications. In the present work we demonstrate their preferentially oriented immobilization on top of a mercaptopropionic acid (MPA) self assembled monolayer (SAM) formed on gold screen printed electrodes (Au-SPE). The AFM of the self assembled biofilm reveals formation of nanohole features with the depths of 2.2–2.5 nm, consistent with the thickness of the BRC (~ 3 nm). Thus, BRCs organize into a sub-monolayer film on top of the MPA SAM layer. The square-wave voltammogram of the BRC films exhibits features due to the redox reactions for the bacteriochlorophyll dimer (the strongest), bacteriopheophytin, and the quinones (weak), indicating that the BRCs are more likely immobilized with the dimer side towards the electrode surface. Non-saturating illumination of the BRC film at open circuit conditions leads to a sharp spike of negative current which could be due to the electron acceptance by the oxidized dimer. 相似文献
88.
A series of novel bisthiacalix[4]arenes with diimine linkages of different aromatic or heteroaromatic dialdehydes have been synthesized. The structure of one of the bisthiacalixarene has been analyzed by X-ray crystallography. These molecules quantitatively extract silver ion from aqueous into organic phase under neutral conditions. 相似文献
89.
Satish K. Tuteja Priyanka Vijayender Bhalla Akash Deep A.K. Paul C. Raman Suri 《Analytica chimica acta》2014
We report lithium ion intercalation mediated efficient exfoliation of graphite to form monolithic graphene sheets which have subsequently been investigated for the development of highly sensitive label-free electrochemical detection platform for cardiac biomarker, Troponin I (cTnI). The spectroscopic and morphological analysis demonstrated the formation of defect free graphene sheets which were successfully employed to fabricate an inter-digited microdevice in a drain-source configuration on a silicon biochip. The graphene gated biochip functionalized with anti-cTnI antibodies used in label free detection of cTnI which exhibited an excellent sensitivity in the picogram range (∼1 pg mL−1) for cTnI without the use of any enzymatic amplification that promises its potential applicability for bio-molecular detection in clinical diagnosis. 相似文献
90.
We report the first spectroscopic study of a complex consisting of a rare earth atom in combination with ammonia. Using two-color resonance-enhanced multiphoton ionization (REMPI) spectroscopy, the lowest energy electronic transition of YbNH(3) has been found in the near-infrared. The spectrum arises from a spin-forbidden transition between the (1)A(1) ground electronic state and the lowest (3)E excited electronic state. The transition is metal centered and approximately correlates with the Yb 6s6p (3)P ← 6s(2) (1)S transition. The observation of clear spin-orbit structure in the spectrum confirms the C(3v) symmetry of YbNH(3). Vibrational structure is also observed in the REMPI spectrum, which is dominated by excitation of the Yb-N stretching vibration. 相似文献