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151.
152.
Ryosuke Sugiyama Takahiro Nakatani Shinichi Nishimura Kei Takenaka Taro Ozaki Shumpei Asamizu Hiroyasu Onaka Hideaki Kakeya 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(38):13620-13625
Organisms often produce secondary metabolites as a mixture of biosynthetically related congeners. However, why are metabolites with minor chemical variations produced simultaneously? 5‐Alkyl‐1,2,3,4‐tetrahydroquinolines (5aTHQs) are small, lipophilic metabolites produced by Streptomyces nigrescens HEK616 when cultured with Tsukamurella pulmonis TP‐B0596. A mixture of 5aTHQs forms aggregates that show enhanced membrane affinity and biological activity. The ability to form aggregates and membrane‐binding activity is regulated by the length of the alkyl chains. Aggregates with long alkyl chains were too stable to fuse with lipid membranes. However, if inactive 5aTHQ congener was mixed with active congener, the mixture showed increased membrane affinity, enabling cellular entry and biological activity. Therefore, it is shown that sloppiness in a biosynthetic pathway, by which minor structural variations can be produced, is functionally rational, as the metabolites show synergistic action. 相似文献
153.
ZrO2 thin films were produced by limited reaction sputtering process varying the deposition parameters. An interesting growth phenomenon was observed in the initial growth stage of amorphous samples, appearing to suppress film growth for the first several minutes. The structures of such ultrathin ZrO2 films were investigated by high-resolution Rutherford backscattering (HR-RBS) and X-ray photoelectron spectroscopy (XPS). The results suggest that the existence of interfacial suboxides due to the adsorption-induced surface reaction and diffusion-induced internal reaction, lead to the deteriorated interfacial performance. The mechanism and effects of the growth delay time on the interfacial characteristics are discussed in detail. 相似文献
154.
Seiichi Taruta Maki Suzuki Tomohiko Yamakami Tomohiro Yamaguchi Kunio Kitajima 《Journal of Non》2008,354(10-11):848-855
In order to crystallize a large quantity of the lithium?mica in glass?ceramics, 5.1 mass% MgF2 was added to the starting materials of the parent glasses having chemical compositions of Li(1+x)Mg3AlSi3(1+x)O10+6.5xF2 (x = 0.5 and 1.0). Transparent glass?ceramics, in which a large quantity of lithium?mica with particle size of <50 nm was separated, could be prepared from the MgF2-added parent glass with x = 0.5. While the parent glass, which had a binodal phase separation structure, did not exhibit electrical conductivity, the transparent glass–ceramic was given conductivity by the formation of an interlocking structure of mica. As the separated mica formed a tighter interlocking structure, the conductivity increased and reached a value of 2.0 × 10?3 S/cm at 600 °C. The MgF2-added parent glass with x = 1.0 was not transparent because of coarse spinodal phase separation. The conductivity was 4.3 × 10?4 S/cm at 600 °C but was significantly decreased by the separation of mica. 相似文献
155.
Li-Hsiang Wang Norihiko Hayase Dr. Haruki Sugiyama Juntaro Nogami Prof. Dr. Hidehiro Uekusa Prof. Dr. Ken Tanaka 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18107-18113
Single and double cyclophenylene–ethynylenes (CPEs) with axial and helical chirality have been synthesized by the Sonogashira cross-coupling of di- and tetraethynyl biphenyls with a U-shaped prearomatic diiodoparaphenylene followed by reductive aromatization. X-ray crystallographic analyses and DFT calculations revealed that the CPEs possess highly twisted bent structures. Bend angles on the edge of the paraphenylene units were close to the value of [5]cycloparaphenylene (CPP)—the smallest CPP to date. The double and single CPEs possessed stable chirality despite flexible biphenyl structures because of the high strain in the diethynyl–paraphenylene moiety. In both the single and double CPEs, orbital interactions along the biphenyl axis were observed by DFT calculations in LUMO and LUMO+2 of the single CPE and LUMO+1 of the double CPE, which likely cause lowering of these orbital energies. Concerning chiroptical properties: boosting of the gabs value was observed in the biphenyl-based double CPE, as well as the binaphthyl-based single CPE, compared to the biphenyl-based single CPE. 相似文献
156.
Yukimasa Aida Juntaro Nogami Dr. Haruki Sugiyama Prof. Dr. Hidehiro Uekusa Prof. Dr. Ken Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(55):12579-12588
The enantioselective synthesis of polycyclic aromatic hydrocarbon (PAH)-based planar chiral cyclophanes was achieved for the first time by the rhodium-catalyzed intramolecular regio- and enantioselective [2+2+2] cycloaddition of tethered diyne-benzofulvenes followed by stepwise oxidative transformations. The thus synthesized planar chiral bent cyclophanes, that possess bent p-terphenyl- and 9-fluorenone-cores, were converted to 9-fluorenol-based ones with excellent ee values of >99 % by diastereoselective 1,2-reduction. These 9-fluorenol-based cyclophanes exhibited high fluorescence quantum yields, which were significantly higher than that of an acyclic reference molecule (78–82 % vs. 48 %). The bending effect on the chiroptical property was also examined, which revealed that the anisotropy factors (gabs values) for electronic circular dichroism (ECD) of these 9-fluorenol-based planar chiral bent cyclophanes increase as the tether length becomes shorter. 相似文献
157.
Dr. Tetsuo Tsuchiya Dr. Tomohiko Nakajima Yuko Uzawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(42):9261-9276
This review summarizes the use of photoreactions that replace conventional heating processes for growing oxide thin films from chemical solutions. In particular, this review outlines key variables in photoreactions that affect epitaxial and polycrystalline thin film growth, including precursor materials, laser wavelength, laser fluence, and carbon. In addition, the features of the photoreaction process that can be controlled at a low temperature by oxygen non-stoichiometry are examined. Likewise, functions that are neither achieved by developing a gradient structure nor controlled by a thermal equilibrium reaction are detailed. Two new concepts are presented, known as photoreaction of nanoparticles (PRNP) and photoreaction of a hybrid solutions (PRHS), in which crystal nuclei are pre-dispersed in a metal–organic compound film. This method has successfully produced flexible phosphor films used as resistor or thermistor electronic components. Finally, thin film growth using different light sources such as flash lamps and femtosecond lasers (fs) is explored. 相似文献
158.
Kentarou Sakamoto Dr. Misao Akishiba Takahiro Iwata Dr. Kazuya Murata Dr. Seiya Mizuno Dr. Kenichi Kawano Dr. Miki Imanishi Prof. Dr. Fumihiro Sugiyama Prof. Dr. Shiroh Futaki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(45):20165-20173
Endocytic pathways are practical routes for the intracellular delivery of biomacromolecules. Along with this, effective strategies for endosomal cargo release into the cytosol are desired to achieve successful delivery. Focusing on compositional differences between the cell and endosomal membranes and the pH decrease within endosomes, we designed the lipid-sensitive and pH-responsive endosome-lytic peptide HAad. This peptide contains aminoadipic acid (Aad) residues, which serve as a safety catch for preferential permeabilization of endosomal membranes over cell membranes, and His-to-Ala substitutions enhance the endosomolytic activity. The ability of HAad to destabilize endosomal membranes was supported by model studies using large unilamellar vesicles (LUVs) and by increased intracellular delivery of biomacromolecules (including antibodies) into live cells. Cerebral ventricle injection of Cre recombinase with HAad led to Cre/loxP recombination in a mouse model, thus demonstrating potential applicability of HAad in vivo. 相似文献
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160.