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排序方式: 共有1149条查询结果,搜索用时 140 毫秒
91.
Joo Hwan Koh Kyung Ju Lee Jin Ah Seo Jong Hak Kim 《Journal of Polymer Science.Polymer Physics》2009,47(15):1443-1451
An amphiphilic comb‐like copolymer consisting of a poly(vinyl chloride) (PVC) backbone and poly((oxyethylene)9 methacrylate) (POEM) side chains, PVC‐graft‐POEM was synthesized via atom transfer radical polymerization. This comb copolymer was complexed with LiCF3SO3 to form a solid polymer electrolyte. FTIR and FT‐Raman spectroscopy indicate that lithium salts are dissolved in the ion conducting POEM domains of microphase‐separated graft copolymer up to 10 wt % of salt concentration. Microphase‐separated structure of the materials and the selective interaction of lithium ions with POEM domains were revealed by transmission electron microscopy, wide angle X‐ray scattering, and differential scanning calorimetry. The maximum ionic conductivity of 4.4 × 10?5 S/cm at room temperature was achieved at 10 wt % of salt concentration, above which salts are present as less mobile species such as ion pairs and higher order ionic aggregates, as characterized by FT‐Raman spectroscopy. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1443–1451, 2009 相似文献
92.
Dr. Chiyoung Park Dr. Beom Joo Yang Ki Beom Jeong Dr. Chae Bin Kim Prof. Seunghyun Lee Dr. Bon-Cheol Ku 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(20):5577-5581
The coordination chemistry of plant polyphenols and metal ions can be used for coating various substrates and for creating modular superstructures. We herein explored this chemistry for the controlled release of guests from mesoporous silica nanoparticles (MSNs). The selective adsorption of tannic acids (TAs) on MSN silica walls opens the MSN mesoporous channels without disturbing mass transport. The channel may be closed by the coordination of TA with CuII ions. Upon exposure to light, photolysis of Trojan horse guests (photoacid generators, PAGs) leads to acid generation, which enables the release of payloads by decomposing the outer coordination shell consisting of TA and CuII. We also fabricated a modular assembly of MSNs on glass substrates. The photoresponsive release characteristics of the resulting film are similar to those of the individual MSNs. This method is a fast and facile strategy for producing photoresponsive nanocontainers by non-covalent engineering of MSN surfaces that should be suitable for various applications in materials science. 相似文献
93.
We propose a new Helmholtz energy of mixing equation following the original Flory–Huggins (F–H) closed-packed lattice model. Also, to overcome F–H mean-field approximation, we introduce new universal constants to consider chain length dependence of polymer in solvent and consider specific interactions to describe strongly interacting polymer systems. Our proposed model successfully describes liquid–liquid equilibria (LLE) for binary polymer–solvent systems using identical interaction parameters which do not depend on the polymer molecular weight. We also describe vapor–liquid equilibria (VLE) for polymer/solvent systems and swelling equilibria of thermosensitive hydrogel systems using the same energy parameters obtained from LLE calculations. 相似文献
94.
Jae Yoon Chung Hwan Won Chung Seung Joo Cho Jung-Mi Hah Art E. Cho 《Journal of computer-aided molecular design》2010,24(5):385-397
Three dimensional (3D) quantitative structure-activity relationship studies of 37 B-Raf inhibitors, pyrazole-based derivatives,
were performed. Based on the co-crystallized compound (PDB ID: 3D4Q), several alignment methods were utilized to derive reliable
comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) models. Receptor-guided
alignment with quantum mechanics/molecular mechanics (QM/MM) minimization led to the best CoMFA model (q
2 = 0.624, r
2 = 0.959). With the same alignment, a statistically reliable CoMSIA model with steric, H-bond acceptor, and hydrophobic fields
was also derived (q
2 = 0.590, r
2 = 0.922). Both models were validated with an external test set, which gave satisfactory predictive r
2 values of 0.926 and 0.878, respectively. Contour maps from CoMFA and CoMSIA models revealed important structural features
responsible for increasing biological activity within the active site and explained the correlation between biological activity
and receptor-ligand interactions. New fragments were identified as building blocks which can replace R1-3 groups through combinatorial
screening methods. By combining these fragments a compound with a high bioactivity level prediction was found. These results
can offer useful information for the design of new B-Raf inhibitors. 相似文献
95.
Sunwoo Kang Sang Joo Lee Shihai Yan Kye Chun Nam Jin Yong Lee 《Journal of inclusion phenomena and macrocyclic chemistry》2010,66(1-2):67-73
We investigated the binding nature of the 1,2,3-alternate calix[6]arene with one piperidine, two piperidines, and two triethyl amines with a special emphasis on the hydrogen bonding networks by density functional theory calculations. The 1,2,3-alternate calix[6]arene strongly binds with piperidines and triethylamines at two different binding sites, exo and endo sites. In the two binding sites, the hydrogen bonding nature shows a characteristic difference. In the exo site, there formed only one hydrogen bond, while in the endo site, two hydrogen bonds except for the triethylamine. The proton transfer within the hydrogen bonding and the hydrogen bonding types, normal hydrogen bonding (NHB), short strong hydrogen bond (SSHB), and low barrier hydrogen bonding (LBHB), will be discussed in detail. 相似文献
96.
Sunwoo Kang Sang Joo Lee Shihai Yan Kye Chun Nam Jin Yong Lee 《Journal of inclusion phenomena and macrocyclic chemistry》2010,66(1-2):75-79
The variations in geometry structure, IR spectra, as well as the molecular orbitals upon anion recognition for polyamide cryptand are explored with the hybrid density functional theory. The cavity generated by six amide NH groups shrinks upon F ? recognition because of the strong hydrogen bonds between the amide protons and F ? , while the cavity expands upon Cl ? binding because of the strong electron repulsion between the p electron of Cl ? and the lone pair electrons of the nitrogen atom of the pyridine moieties. The “electropositive field space” …Cl ? coupling exists when Cl ? is recognized. The strong anion binding energy with F ? indicates that the polyamide cryptand prefers F ? to Cl ? . 相似文献
97.
Hyeong Jin Yun Hyunjoo Lee Ji Bong Joo Nam Dong Kim Jongheop Yi 《Electrochemistry communications》2010,12(6):769-772
We describe a method tuning the band-gap energy (Eg) of visible light sensitive TiO2-xCx nanoparticle. Eg tends to become smaller with the increase in the amount of carbon dopant in TiO2-xCx nanoparticle due to the increase in excess electrons. Photo-catalytic oxidative activity, however, did not depend on only the value of Eg, but also the energy level of valence band. TiO1.96C0.04 nanoparticle having Eg of 2.6 eV showed outstanding performance in oxidative decomposition of phenol under the irradiation of visible light. 相似文献
98.
99.
An analytical method of CE-MS and CE with an online preconcentration technique induced by a dynamic pH junction, addition of organic solvent and large volume injection was developed for sensitive determination of peptides in biological samples. Leucine enkephalin, methionine enkephalin, dynorphin A, β-endorphin and angiotensin II were used as model peptides. The optimal online preconcentration conditions were obtained at a sample matrix consisting of 100?mM borate buffer (pH 10.0) with 50% v/v acetonitrile and a BGE containing 1?M formic acid at pH 2.0, along with a 25-cm injection length. Under the optimized conditions, a 4.0×10(3)-1.1×10(4)-fold increase in peak intensity was achieved without degrading the peak shape. This online preconcentration method was applied to analyze the intracellular angiotensin II within the peptides extracted from HL1 cells and approximately increase of 1×10(4)-fold sensitivity was achieved compared to normal condition. Thus, the developed method could be applied to the analysis of various peptides for peptidomics study in biological samples. 相似文献
100.
Min Kyong Moon Min Kim Sung Soo Chung Hyun Joo Lee Sung Hee Koh Peter Svovoda Myung Hee Jung Young Min Cho Young Joo Park Sung Hee Choi Hak Chul Jang Kyong Soo Park Hong Kyu Lee 《Experimental & molecular medicine》2010,42(5):345-352
An association between inflammatory processes and the pathogenesis of insulin resistance has been increasingly suggested. The IκB kinase-β (IKK-β)/ nuclear factor-κB (NF-κB) pathway is a molecular mediator of insulin resistance. S-Adenosyl-L-methionine (SAM) has both antioxidative and anti-inflammatory properties. We investigated the effects of SAM on the glucose transport and insulin signaling impaired by the tumor necrosis factor α (TNFα) in 3T3-L1 adipocytes. SAM partially reversed the basal and insulin stimulated glucose transport, which was impaired by TNFα. The TNFα-induced suppression of the tyrosine phosphorylation of the insulin receptor substrate-1 (IRS-1) and Akt in 3T3-L1 adipocytes was also reversed by SAM. In addition, SAM significantly attenuated the TNFα-induced degradation of IκB-α and NF-κB activation. Interestingly, SAM directly inhibited the kinase activity of IKK-β in vitro. These results suggest that SAM can alleviate TNFα mediated-insulin resistance by inhibiting the IKK-β/NF-κB pathway and thus can have a beneficial role in the treatment of type 2 diabetes mellitus. 相似文献