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561.
562.
Synthesis, characterization, molecular structure, and redox properties of a new quinoidal terthiophene incorporated with a thieno[3,4-c]pyrrole moiety (5) are described. Although an electrochemical reduction of 5 formally produces the non-classical thieno[3,4-c]pyrrole moiety, 5 showed a reversible reduction wave on cyclic voltammogram, indicating that the thieno[3,4-c]pyrrole moiety can be stabilized by delocalized 10π-conjugated system in the dianion state of 5. However, the reduction potential was largely affected by incorporation of the thieno[3,4-c]pyrrole and shifted cathodically by 0.4 V compared to that of the parent quinodial terthiophene (1). 相似文献
563.
Certified reference material for quantification of polycyclic aromatic hydrocarbons in sediment from the National Metrology Institute of Japan 总被引:2,自引:0,他引:2
Nobuyasu Itoh Yoshie Aoyagi Akiko Takatsu Takashi Yarita 《Analytical and bioanalytical chemistry》2009,393(8):2039-2049
The National Metrology Institute of Japan has issued a certified reference material (CRM) of freshwater lake sediment for
polycyclic aromatic hydrocarbon (PAHs) analyses. The certification used three extraction techniques: pressurized liquid extraction
(PLE) with toluene, PLE with dichloromethane/ethyl acetate (1:1 by volume), and alkaline extraction (1 M KOH in methanol)
in combination with microwave-assisted extraction. Both gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/dopant-assisted
atmospheric pressure photoionization/MS (LC/DA-APPI/MS) analyses were used. Certified values are provided for 18 PAHs at 1–25 μg
kg−1 except for perylene (2.08 × 103 μg kg−1), and information values are provided for two. Since the values of PAHs in the CRM are much lower than those in other CRMs
and are comparable to those found at sites with little human influence, the CRM is suitable for PAH monitoring in sediment
and soil samples. 相似文献
564.
Magnesium (Mg) coated with four kinds of polymers, poly (l-lactic acid) (PLLA)-high molecular weight (HMW), PLLA-low molecular weight (LMW), poly (?-caprolactone) (PCL)-HMW and PCL-LMW, and uncoated Mg were immersed under cell culture condition to study the degradation/corrosion behavior of the polymer-coated Mg. The releases of Mg2+ are measured during the immersion. Surface morphology and chemical composition are observed and identified by SEM and EDX. The tomography is obtained by X-ray CT observation and degradation rate is calculated by image analysis after 10-day immersion. All kinds of polymer-coated Mg showed significantly low release of Mg2+ (p < 0.05) in the whole immersion process comparing to that of uncoated Mg. In SEM and EDX results show, a corrosion layer can be observed on both polymer-coated and uncoated Mg after immersion. There is no obvious difference on the morphology and chemical composition of the corrosion layer between polymer-coated and uncoated Mg, indicating the corrosion/degradation process and corrosion product of Mg substrate are not changed by the polymer films under the present condition compared with uncoated Mg. Concerning the tomography and degradation rate of 10-day immersion, it can be found that the polymer-coated Mg shows a significantly low corrosion rate (p < 0.05) compared with that of uncoated Mg. PLLA coated Mg shows relatively uniform corrosion than PCL coated Mg and uncoated Mg. The largest pitting corrosion depth of PCL-LMW is about 3 times as large as the PLLA-LMW, which might be attributed to the difference of polymer microstructure. It is suggested that PLLA coating might be a suitable option for retarding the loss of mechanical properties of Mg substrate. 相似文献
565.
Akiko Nagata Kazuto Iijima Ryota Sakamoto Yuka Mizumoto Miho Iwaki Masaki Takiwaki Yoshikuni Kikutani Seketsu Fukuzawa Minami Odagi Masayuki Tera Kazuo Nagasawa 《Molecules (Basel, Switzerland)》2022,27(8)
Blood levels of the vitamin D3 (D3) metabolites 25-hydroxyvitamin D3 (25(OH)D3), 24R,25-dihydroxyvitamin D3, and 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) are recognized indicators for the diagnosis of bone metabolism-related diseases, D3 deficiency-related diseases, and hypercalcemia, and are generally measured by liquid-chromatography tandem mass spectrometry (LC-MS/MS) using an isotope dilution method. However, other D3 metabolites, such as 20-hydroxyvitamin D3 and lactone D3, also show interesting biological activities and stable isotope-labeled derivatives are required for LC-MS/MS analysis of their concentrations in serum. Here, we describe a versatile synthesis of deuterium-labeled D3 metabolites using A-ring synthons containing three deuterium atoms. Deuterium-labeled 25(OH)D3 (2), 25(OH)D3-23,26-lactone (6), and 1,25(OH)2D3-23,26-lactone (7) were synthesized, and successfully applied as internal standards for the measurement of these compounds in pooled human serum. This is the first quantification of 1,25(OH)2D3-23,26-lactone (7) in human serum. 相似文献
566.
Emerald R. Taylor Akiko Sato Isobel Jones Prashant G. Gudeangadi David M. Beal James A. Hopper Wei-Feng Xue Michael R. Reithofer Christopher J. Serpell 《Chemical science》2022,14(1):196
DNA–peptide conjugates offer an opportunity to marry the benefits of both biomolecular classes, combining the high level of programmability found with DNA, with the chemical diversity of peptides. These hybrid systems offer potential in fields such as therapeutics, nanotechnology, and robotics. Using the first DNA–β-turn peptide conjugate, we present three studies investigating the self-assembly of DNA–peptide conjugates over a period of 28 days. Time-course studies, such as these have not been previously conducted for DNA–peptide conjugates, although they are common in pure peptide assembly, for example in amyloid research. By using aging studies to assess the structures produced, we gain insights into the dynamic nature of these systems. The first study explores the influence varying amounts of DNA–peptide conjugates have on the self-assembly of our parent peptide. Study 2 explores how DNA and peptide can work together to change the structures observed during aging. Study 3 investigates the presence of orthogonality within our system by switching the DNA and peptide control on and off independently. These results show that two orthogonal self-assemblies can be combined and operated independently or in tandem within a single macromolecule, with both spatial and temporal effects upon the resultant nanostructures.DNA and peptide nanotechnologies can be interfaced to create hierarchical and emergent superstructures, which evolve with time. 相似文献
567.
Hisayasu Ishibashi Dr. Manuel Rondelli Hiroki Shudo Prof. Dr. Takehisa Maekawa Prof. Dr. Hideto Ito Prof. Dr. Kiichi Mizukami Prof. Dr. Nobuo Kimizuka Prof. Dr. Akiko Yagi Prof. Dr. Kenichiro Itami 《Angewandte Chemie (International ed. in English)》2023,62(44):e202310613
The active metal template (AMT) strategy is a powerful tool for the formation of mechanically interlocked molecules (MIMs) such as rotaxanes and catenanes, allowing the synthesis of a variety of MIMs, including π-conjugated and multicomponent macrocycles. Cycloparaphenylene (CPP) is an emerging molecule characterized by its cyclic π-conjugated structure and unique properties. Therefore, diverse modifications of CPPs are necessary for its wide application. However, most CPP modifications require early stage functionalization and the direct modification of CPPs is very limited. Herein, we report the synthesis of a catenane consisting of [9]CPP and a 2,2′-bipyridine macrocycle as a new CPP analogue that contains a reliable synthetic scaffold enabling diverse and concise post-modification. Following the AMT strategy, the [9]CPP-bipyridine catenane was successfully synthesized through Ni-mediated aryl-aryl coupling. Catalytic C−H borylation/cross-coupling and metal complexation of the bipyridine macrocycle moiety, an effective post-functionalization method, were also demonstrated with the [9]CPP-bipyridine catenane. Single-crystal X-ray structural analysis revealed that the [9]CPP-bipyridine catenane forms a tridentated complex with an Ag ion inside the CPP ring. This interaction significantly enhances the phosphorescence lifetime through improved intermolecular interactions. 相似文献