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541.
Hong YK Bahng JH Lee G Kim H Kim W Lee S Koo JY Park JI Lee WR Cheon J 《Chemical communications (Cambridge, England)》2003,(24):3034-3035
A simple procedure for the fabrication of sub-10 nm scale Si nanopillars in a 2-D array using reactive ion etching with 8 nm Co nanoparticles as etch masks is demonstrated. The obtained Si nanopillars are single crystalline tapered pillar structures of 5 nm (top) x 8 nm (bottom) with a density of approximately 4 x 10(10) pillars cm(-2) on the substrate, similar to the density of Co nanoparticles distributed before the ion etching process. The uniform spatial distribution of the Si nanopillars can also be patterned into desired positions. Our fabrication method is straightforward and requires mild process conditions, which can be extended to patterned 2-D arrays of various Si nanostructures. 相似文献
542.
Kim HJ Rho YH Choi SJ Lee YH Cheon H Um JW Sohn J Song GG Ji JD 《Experimental & molecular medicine》2005,37(3):179-185
15-deoxy-delta(12,14)-PGJ(2)(15d-PGJ(2)) is a natural ligand that activates the peroxisome proliferators-activated receptor (PPAR) gamma, a member of nuclear receptor family implicated in regulation of lipid metabolism and adipocyte differentiation. Recent studies have shown that 15d-PGJ(2) is the potent anti-inflammatory agent functioning via PPARgamma-dependent and -independent mechanisms. Most postulated mechanisms for anti-inflammatory action of PPARgamma agonists are involved in inhibiting NF-kappaB signaling pathway. We examined the possibility that IL-6 signaling via the Jak-Stat pathway is modulated by 15d-PGJ(2) in lymphocytes and also examined whether the inhibition of IL-6 signaling is dependent of PPARgamma. 15d-PGJ(2) blocked IL-6 induced Stat1 and Stat3 activation in primary human lymphocytes, Jurkat cells and immortalized rheumatoid arthritis B cells. Inhibition of IL-6 signaling was induced rapidly within 15 min after treatment of 15d-PGJ(2). Other PPARgamma-agonists, such as troglitazone and ciglitazone, did not inhibit IL-6 signaling, indicating that 15d-PGJ(2) affect the IL-6-induced Jak-Stat signaling pathway via PPARgamma-independent mechanism. Although cycloheximide reversed 15d-PGJ(2)-mediated inhibition of Stat3 activation, actinomycin D had no effect on 15d-PGJ(2)-mediated inhibition of IL-6 signaling, indicating that inhibition of IL-6 signaling occur independent of de novo gene expression. These results show that 15d-PGJ(2) specifically inhibit Jak-Stat signaling pathway in lymphocytes, and suggest that 15d-PGJ(2) may regulate inflammatory reactions through the modulation of different signaling pathway other than NF-kappaB in lymphocytes. 相似文献
543.
Dimerization of chloroaluminum (III) phthalocyanine tetrasulfonates (AIPCS) has been observed in different aqueous alcoholic solvents at room temperature by absorption and fluorescence spectroscopic methods. Both absorption and fluorescence spectral bands of the dimer are red shifted by ca 550 cm-1 from the monomer Q bands in the corresponding spectra, suggesting that the interaction energy between the two monomer subunits is very weak. The fluorescence lifetime of the dimer is longer ( ca 9.5 ns) than that of the monomer ( ca 7–8 ns). These spectral behaviors of AIPCS dimer contrast with those of transition-metallaloid phthalocyanine dimers, which usually have a nonfluorescent face-to-face stacking conformation. The dimer fluorescence is interpreted to be due to the fact that the lowest excited singlet state of the dimer is lower in energy than a charge-resonance state, based on the excitoncoupling theory applied to the face-to-face slipping conformation. The dimerization constant determined spectrometrically decreases with an increase of water content in the aqueous alcoholic solution. Propanol and ethanol have been observed to be more effective than methanol in promoting dimerization. These results indicate that a specific interaction of water with AIPCS plays an important role in the inhibition of dimerization of AIPCS. 相似文献
544.
E. A. J. Bartis A. J. Knoll P. Luan J. Seog G. S. Oehrlein 《Plasma Chemistry and Plasma Processing》2016,36(1):121-149
We review studies of surface-interaction mechanisms for a surface microdischarge (SMD) and an atmospheric pressure plasma jet (APPJ) with model polymers and biomolecules in our laboratory. We discuss the influence of plasma source type, operating parameters, and gaseous environments on surface modifications and biological deactivation. We focus on mild, remote conditions where the visible plasma plume does not contact the surface. For an APPJ fed with Ar, the interaction of the plasma plume with O2 and/or N2 gaseous environments leads to oxidation and surface-bound NOx even on materials containing neither oxygen nor nitrogen. The APPJ also modifies photo-sensitive polymers. Using optical filters, these modifications were shown to result in part from irradiation with vacuum ultraviolet (VUV) photons in a spectral range corresponding to Ar excimer emission. No VUV-induced effects were seen for the SMD source operated with O2/N2. SMD treatments using O2/N2 mixtures result in surface oxidation and nitridation. A new surface-bound species, NO3, has been measured on the polymers and biomolecules. Depending on the gas chemistry and film molecular structure, the NO3 surface concentration can reach 10 %. Both surface NO3 on plasma-treated films of lipopolysaccharide (LPS), an immune stimulating biomolecule found in bacteria such as E. c oli, and overall surface oxidation correlate with LPS biological deactivation as evaluated using an enzyme-linked immunosorbent assay. Ambient humidity was studied using the SMD and was found to decrease overall surface modifications including NO3 and biodeactivation for O2-rich conditions. Lastly, we discuss possible mechanisms and compare our results with published simulation studies. 相似文献
545.
Remarkable Differences in Reactivity between Benzothiazoline and Hantzsch Ester as a Hydrogen Donor in Chiral Phosphoric Acid Catalyzed Asymmetric Reductive Amination of Ketones
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Described herein are differences in behavior between a Hantzsch ester and a benzothiazoline as hydrogen donors in the chiral phosphoric acid catalyzed asymmetric reductive amination of ketones with p‐anisidine. The asymmetric reductive amination of ketones with a Hantzsch ester as a hydrogen donor provided the corresponding chiral amines exclusively, regardless of the structures of the ketones, whereas a similar transformation with a benzothiazoline provided chiral amines and p‐methoxyphenyl‐protected primary amines in variable yields, depending on the structures of both the ketones and benzothiazolines. Because a benzothiazoline has an N,S‐acetal moiety that is vulnerable to p‐anisidine, the primary amine can be formed through transimination of the benzothiazoline with p‐anisidine followed by reduction of the resulting aldimine with remaining benzothiazoline. 相似文献
546.
547.
Wayne David M. Stritzinger Jared T. Casella Amanda J. Sweet Lucas E. Corbey Jordan F. Garcia Daniel J. Wylie E. Miller Tandon Lav Olson Angela C. Rim Jung Ho 《Journal of Radioanalytical and Nuclear Chemistry》2021,329(2):741-756
Journal of Radioanalytical and Nuclear Chemistry - A 30 year-old PuF4 sample consisting of brown powder (PuF4-b) and pink granules (PuF4-p) was analyzed. X-ray diffraction shows the bulk... 相似文献
548.
Gyeong Do Park Yoon-Hee Cheon So Young Eun Chang Hoon Lee Myeung Su Lee Ju-Young Kim Hae Joong Cho 《Molecules (Basel, Switzerland)》2021,26(9)
Osteoporosis is a systemic metabolic bone disorder that is caused by an imbalance in the functions of osteoclasts and osteoblasts and is characterized by excessive bone resorption by osteoclasts. Targeting osteoclast differentiation and bone resorption is considered a good fundamental solution for overcoming bone diseases. β-boswellic acid (βBA) is a natural compound found in Boswellia serrata, which is an active ingredient with anti-inflammatory, anti-rheumatic, and anti-cancer effects. Here, we explored the anti-resorptive effect of βBA on osteoclastogenesis. βBA significantly inhibited the formation of tartrate-resistant acid phosphatase-positive osteoclasts induced by receptor activator of nuclear factor-B ligand (RANKL) and suppressed bone resorption without any cytotoxicity. Interestingly, βBA significantly inhibited the phosphorylation of IκB, Btk, and PLCγ2 and the degradation of IκB. Additionally, βBA strongly inhibited the mRNA and protein expression of c-Fos and NFATc1 induced by RANKL and subsequently attenuated the expression of osteoclast marker genes, such as OC-STAMP, DC-STAMP, β3-integrin, MMP9, ATP6v0d2, and CtsK. These results suggest that βBA is a potential therapeutic candidate for the treatment of excessive osteoclast-induced bone diseases such as osteoporosis. 相似文献
549.
Dr. Ye Ri Han Jae Soon Kim Woo-Jin Park Dr. Chang-Hee Lee Prof. Dr. Jinwoo Cheon Prof. Dr. Chul-Ho Jun 《化学:亚洲杂志》2021,16(3):197-201
Well-defined recyclable Pd- and Rh-bipyridyl group-impregnated SBA-15 catalysts were prepared for C−C bond coupling reaction and selective hydrogenation reactions, respectively. These SBA-15 derived ligands for the catalysts were prepared by direct and indirect co-condensation method using bipyridyl-linked methallylsilane. This indirect method, involving methoxysilane generated from methallylsilane shows higher loading efficiency of transition metal catalysts on SBA-15 than the direct use of methallylsilane. 相似文献
550.
Amrita Chatterjee Dr. Dong Ju Oh Kyung Mi Kim Kyung‐Seog Youk Kyo Han Ahn Prof. 《化学:亚洲杂志》2008,3(11):1962-1967
A colorimetric sensing system based on gold nanoparticles functionalized with a water‐soluble anion‐recognition motif, an o‐(carboxamido)trifluoroacetophenone analogue, has been developed. The nanoparticle system selectively senses specific isomers of dicarboxylates that are geometrically favorable for the binding‐induced aggregation process; thus, it discriminates a trans‐dicarboxylate fumarate from its cis‐isomer maleate, and benzene‐1,4‐dicarboxylate from its isomeric benzene‐1,2‐and benzene‐1,3‐dicarboxylates in water, exhibiting a color change from red to blue. 相似文献