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91.
We obtained the chemical shielding constants of 29Si in Li2S–SiS2 glass system on the basis of molecular orbital calculations. The relative chemical shieldings calculated at the HF/6-31G* level is −16.1 and −23.8 ppm for E(1) and E(0), respectively. These calculations are in good agreement with the previous NMR study: σ(E(2))>σ(E(1))>σ(E(0)). It is found theoretically that incorporation of Li2S into SiS2 does not influence the 29Si chemical shift, while incorporation of Li2O into SiO2 does to a significant extent. It is also found that the existence of oxygen in Li2S–SiS2 glasses increases the chemical shielding of 29Si by about 25 ppm, which is in good agreement with the experimental result. 相似文献
92.
The diastereoselective construction of stereotriads having consecutive methyl, hydroxy, and methyl substituents was realized by the substrate-controlled crotylation of beta-branched alpha-methylaldehydes with potassium crotyltrifluoroborates. Especially, crotylation of 2-(1,3-dithian-2-yl)propanal with potassium ( E)-crotyltrifluoroborate afforded, in good yield and with excellent diastereoselectivity, a useful building block that has different and potential functional groups on both ends. 相似文献
93.
Population study of sizes and components of self-reproducing giant multilamellar vesicles 总被引:1,自引:0,他引:1
Toyota T Takakura K Kageyama Y Kurihara K Maru N Ohnuma K Kaneko K Sugawara T 《Langmuir : the ACS journal of surfaces and colloids》2008,24(7):3037-3044
Population analysis of a system of self-reproducing giant multilamellar vesicles (GMVs) was carried out by means of flow cytometry. The multidimensional distribution of forward light scattering (FS), side light scattering (SS), and fluorescence (FL) intensities originating from each GMV provided information about changes in a population composed of 104 vesicles. FS-FL dot plots indicated that, after the addition of the membrane precursor, the size distribution of the newly generated vesicles was nearly the same as that of the original, but the catalyst content was reduced. This result can be interpreted as evidence for the occurrence of the self-reproduction of GMVs. Moreover, the new GMVs recovered the amount of catalyst to the initial value, keeping their size distribution constant, when a solution of the catalyst was added to the new GMVs. These results are the first experimental evidence for a novel phenomenon on GMV size distribution during their self-reproducing cycle. 相似文献
94.
95.
96.
Reengineering a natural riboswitch by dual genetic selection 总被引:2,自引:0,他引:2
97.
Shimaoka H Kuramoto H Furukawa J Miura Y Kurogochi M Kita Y Hinou H Shinohara Y Nishimura S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(6):1664-1673
The development of rapid and efficient methods for high-throughput protein glycomics is of growing importance because the glycoform-focused reverse proteomics/genomics strategy will greatly contribute to the discovery of novel biomarkers closely related to cellular development, differentiation, growth, and aging as well as a variety of diseases such as cancers and viral infection. Recently, we communicated that rapid and efficient purification of carbohydrates can be achieved by employing sugar-specific chemical ligation with aminooxy-functionalized polymers, which we termed "glycoblotting" (see S.-I. Nishimura et al., Angew. Chem. 2005, 117, 93-98; Angew. Chem. Int. Ed. 2005, 44, 91-96). The chemoselective blotting of oligosaccharides present in crude biological materials onto synthetic polymers relies on the unique oxime-bond formation between aminooxy group displayed on the supporting materials and aldehyde/ketone group at the reducing terminal of all oligosaccharides, thus enabling highly selective and rapid oligosaccharide purification. Aiming to improve the detection sensitivity of the released oligosaccharides, we introduce here a novel strategy for one-pot solid-phase glycoblotting and probing by transoximization. We found that oligosaccharides captured by the polymer supports via the oxime bond can be released in the presence of excess O-substituted aminooxy derivatives in a weakly acidic condition. The released oligosaccharides could be recovered as newly formed oxime derivatives of the O-substituted aminooxy compound added, thus demonstrating the simultaneous releasing and probing. In addition, we synthesized a novel aminooxy-functionalized monomer, N-[2-[2-(2-tert-butoxycarbonylaminooxyacetylamino-ethoxy)ethoxy]ethyl]-2-methacrylamide, which allows for the large-scale preparation of a versatile polymer characterized by its high stability, high blotting capacity, and easy use. The one-pot protocol allowed to profile 23 kinds of N-glycan chains of human serum glycoproteins. This concept was further applied for the glycopeptides analysis in a crude mixture followed by galactose oxidase treatment to generate free aldehyde group at the non-reducing terminal of oligosaccharide moiety of glycopeptides. Our technique may be implemented in existing biochemistry and molecular diagnostics laboratories because enriched oligosaccharides and glycopeptides by solid-phase transoximization with high-sensitive labeling reagents are widely applicable in a variety of common analytical methods using two-dimensional HPLC, LC/MS, and capillary electrophoresis as well as modern mass spectrometry. 相似文献
98.
Hamada T Miura Y Ishii K Araki S Yoshikawa K Vestergaard M Takagi M 《The journal of physical chemistry. B》2007,111(37):10853-10857
The dynamic response of a raft-exhibiting giant liposome to external stimuli, such as the addition of Triton X-100 or osmotic stress, was studied. We observed that daughter vesicles are generated inside of the liposome through endocytic budding. It was found that the budding to generate daughter vesicles is classified into two different routes, simple budding through the invagination of a whole raft and budding from the boundary of a raft accompanied by waving motion. Smaller rafts show a preference for simple budding, whereas large rafts mainly adopt the other process. We discuss the mechanism of this difference in terms of the kinetic pathway of internalization by considering the line energy and bending energy of the membrane. 相似文献
99.
Novel particles having designed hairs were prepared by living radical graft-polymerization on core particles. The living radical species used in this study was a kind of photo-iniferter, N, N-diethyl-thiocarbamate. Main component of hair was poly(N-isopropylacrylamide) (PNIPAM) which was a representative thermo-sensitive polymer. The polymerization was carried out by UV irradiation at room temperature that was lower than the transition temperature of PNIPAM. Incorporation of a small amount of acrylic acid into the hair caused significant change in the properties of hairy particles. The mode of comonomer charge also enabled to design the hair structure on the particles. 相似文献
100.
The kinetics of the thermal isomerization of palladium dithizonate (Pd(HDZ)2) in the binary mixture of toluene and alcohols has been studied. In the solvent effects on the Pd(HDZ)2 isomerization rates, we found that the maximum lies in the range x = 0.02 ∼ 0.2 (x represents the mole fraction of alcohols). The experimental kinetic data for the specific solvent effect with maximum can be reproduced well by taking into account hydrogen bonding and coordination of alcohols with Pd(HDZ)2. The rate constants for the thermal isomerization of Pd(HDZ)2 involving hydrogen bonding and the coordinate interaction with 1‐butanol are evaluated. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 542–547, 2000 相似文献