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121.
MCM-22分子筛的酸性及在1-丁烯骨架异构化反应中的催化性能 总被引:2,自引:0,他引:2
采用XRD,NH3-TPD及氘代乙腈吸附FT-IR等技术表征了静态水热合成法合成的MCM-22分子筛的晶相结构和酸性. 根据表征结果,Si/Al比为15和30的两个样品均为高纯度的MCM-22分子筛; 两个样品的Brnsted酸量基本相同,但Si/Al为15的样品上含有相对较高的Lewis酸量. MCM-22分子筛上1-丁烯骨架异构化反应的结果表明,Si/Al为30的样品具有较高的异丁烯选择性(74.8%)和稳定性, 而Si/Al为15的样品中存在的含量较高的Lewis酸位可能是导致异丁烯选择性(65.5%)下降的主要原因. 相似文献
122.
A series of diverse indole-based chemotypes were synthesized from -tetrahydrocarboline (-THC) scaffolds prepared from commercially and readily available tryptamines and -ketoesters. Diversity can be generated within these chemotypes through the following strategies: (a) appendage of substituents to the -THC scaffold, prepared in situ or as a template, through further elaboration and (b) skeletal modifications to the -THC scaffold via ring forming or ring breaking reactions. The strategies described here are amenable to high throughput solution-phase parallel synthesis, providing access to novel indole-based screening libraries for drug discovery.Dedicated to Professor Spyros P. Perlepes 相似文献
123.
Hong Hai Tomoo Miura Tomoyoshi Kobayashi Yuichiro Maéda Masao Miki 《Journal of fluorescence》2000,10(2):193
Contraction of vertebrate striated muscle is regulated by the strong Ca2+-dependent interaction among troponin (Tn), tropomyosin (Tm), and actin on the thin filament. Using fluorescence resonance energy transfer (FRET), the interactions between Tm and the Tn complex or between Tm and the Tn subunit, TnI or TnC, with or without other troponin subunits, were characterized in the presence or absence of F-actin and Ca2+ ions. Cys-190 of Tm was selectively labeled with the acceptor probe, 4-dimethylaminophenylazophenyl 4-maleimide. Troponin was selectively labeled at position 9 or 133 of TnI and position 98 of TnC with a donor probe, 5-(2-iodoacetylaminoethyl)aminonaphtha lene 1-sulfonic acid. FRET measurements indicate that the interaction between TnI and Tm alone is very weak, but that in the presence of F-actin, TnI binds to the proper binding site on Tm even in the absence of TnT. The distances between Cys-190 of Tm on F-actin and Cys-9 or Cys-133 of Tnl or Cys-98 of TnC in the reconstituted Tn were determined to be 52.8, 53.7, Å and 56.5 Å, respectively, in the absence of Ca2+, indicating that the Tnl—TnC complex, the globular portion of Tn, is located near Cys-190 of Tm on the reconstituted thin filaments. Upon binding of Ca2+ to TnC, these distances increased by 5.6 and 1.4 Å or decreased by 5.4 Å, respectively. These Ca2+-induced changes in Tn—Tm seem to occur only when F-actin is present, suggesting that the stable complex formation of TnI with the outer domain of F-actin upon removal of Ca2+ is a very important event during inhibition. 相似文献
124.
Guiraud S Alimi-Guez D van Wittenberghe L Scherman D Kichler A 《Macromolecular bioscience》2011,11(5):590-594
Muscle is an important and attractive target for gene therapy. Recent findings have shown that neutral amphiphilic triblock copolymers with a PEO-PPO-PEO arrangement significantly increase muscle transfection as compared to naked DNA. We were interested in evaluating whether reverse Pluronics (PPO-PEO-PPO) also possess transfection properties. Therefore, we measured the in vitro and in vivo transfection activity of 25R2 and 25R4, two copolymers that differ by their hydrophilic/hydrophobic balance. The results show that 25R2 significantly increases the transfection level in muscle compared to naked DNA. Taken together, this work demonstrates that the reverse Pluronic 25R2 possesses interesting properties for in vivo transfection. 相似文献
125.
In this short communication we describe a specific protocol for SDS-PAGE separation of adult bovine myosin heavy-chain (MyHC) isoforms. The conditions defined in this protocol allow a good separation with a good reproducibility of the four MyHC isoforms (MyHC I, IIa, IIx, IIb) identified in adult skeletal muscle of this species. This procedure uses mini-gel electrophoresis system and does not involve preparation of gradient separating gels. In addition, this protocol can also be applied to the electrophoretic separation of ovine and camel MyHC isoforms. 相似文献
126.
Refat M. Nimer Khalid M. Sumaily Arwa Almuslat Mai Abdel Jabar Essa M. Sabi Mohammad A. Al-Muhaizea Anas M. Abdel Rahman 《Molecules (Basel, Switzerland)》2022,27(12)
Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder characterized by progressive muscle loss, leading to difficulties in movement. Mutations in the DMD gene that code for the protein dystrophin are responsible for the development of DMD disorder, where the synthesis of this protein is completely halted. Therefore, circulating dystrophin protein could be a promising biomarker of DMD disease. Current methods for diagnosing DMD have sensitivity, specificity, and reproducibility limitations. Herein, a quantitative liquid chromatography–tandem spectrometry (LC–MS/MS) technique in multiple reaction monitoring (MRM) mode was designed and validated for accurate dystrophin protein measurement in a dried blood spot (DBS). The method was successfully validated on the basis of international guidelines regarding calibration curves, precision, and accuracy. In addition, patients and healthy controls were used to test the amount of dystrophin protein circulating in DBS samples as a potential biomarker for DMD disorders. DMD patients were found to have considerably lower levels than controls. To the best of our knowledge, this is the first study to report dystrophin levels in DBS through LC–MS/MS as a diagnostic marker for DMD to the proposed MRM method, providing a highly specific and sensitive approach to dystrophin quantification in a DBS that can be applied in DMD screening. 相似文献
127.
Skeletal editing involves making specific point-changes to the core of a molecule through the selective insertion, deletion or exchange of atoms. It thus represents a potentially powerful strategy for the step-economic modification of complex substrates and is a perfect complement to methods such as C−H functionalization that target the molecular periphery. Given their ubiquity in biologically active compounds, the ability to perform skeletal editing on – and therefore interconvert between – aromatic heterocycles is especially valuable. This review summarizes both recent and key historical examples of skeletal editing as applied to interconversion of aromatic rings; we anticipate that it will serve to highlight not only the innovative and enabling nature of current skeletal editing methods, but also the tremendous opportunities that still exist in the field. 相似文献