全文获取类型
收费全文 | 538篇 |
免费 | 16篇 |
国内免费 | 1篇 |
专业分类
化学 | 480篇 |
晶体学 | 6篇 |
力学 | 1篇 |
数学 | 24篇 |
物理学 | 44篇 |
出版年
2023年 | 6篇 |
2022年 | 38篇 |
2021年 | 41篇 |
2020年 | 17篇 |
2019年 | 8篇 |
2018年 | 10篇 |
2017年 | 8篇 |
2016年 | 27篇 |
2015年 | 15篇 |
2014年 | 32篇 |
2013年 | 41篇 |
2012年 | 32篇 |
2011年 | 43篇 |
2010年 | 21篇 |
2009年 | 21篇 |
2008年 | 29篇 |
2007年 | 30篇 |
2006年 | 28篇 |
2005年 | 14篇 |
2004年 | 20篇 |
2003年 | 19篇 |
2002年 | 15篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 7篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1985年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
排序方式: 共有555条查询结果,搜索用时 15 毫秒
91.
Beata?A.?Zasońska Helena?Hlídková Eduard?Petrovsky Severyn?Myronovskij Tetyana?Nehrych Nazar?Negrych Mariya?Shorobura Volodymyr?Antonyuk Rostyslav?Stoika Yuriy?Kit Daniel?HorákEmail authorView authors OrcID profile 《Mikrochimica acta》2018,185(5):262
Monodisperse nonmagnetic macroporous poly(glycidyl methacrylate) (PGMA) microspheres were synthesized by multistep swelling polymerization of glycidyl methacrylate, ethylene dimethacrylate and 2-[(methoxycarbonyl)methoxy]ethyl methacrylate (MCMEMA). This was followed (a) by ammonolysis to modify the microspheres with amino groups, and (b) by incorporation of iron oxide (γ-Fe2O3) into the pores to render the particles magnetic. The resulting porous and magnetic microspheres were characterized by scanning and transmission electron microscopy (SEM and TEM), atomic absorption and Fourier transform infrared spectroscopy (AAS and FTIR), elemental analysis, vibrating magnetometry, mercury porosimetry and Brunauer-Emmett-Teller adsorption/desorption isotherms. The microspheres are meso- and macroporous, typically 5 μm in diameter, contain 0.9 mM · g?1 of amino groups and 14 wt.% of iron according to elemental analysis and AAS, respectively. The particles were conjugated to p46/Myo1C protein, a potential biomarker of autoimmune diseases, to isolate specific autoantibodies in the blood of patients suffering from multiple sclerosis (MS). The p46/Myo1C loaded microspheres are shown to enable the preconcentration of minute quantities of specific immunoglobulins prior to their quantification via SDS-PAGE. The immunoglobulin M (IgM) with affinity to Myo1C was detected in MS patients. 相似文献
92.
Beata Pospiech 《Chemical Papers》2018,72(2):301-308
This work focuses on the application of polymer inclusion membrane (PIM) with tricaprylmethylammonium thiosalicylate, [A336][TS] (TOMATS), a thiol-containing task-specific ionic liquid for the transport of Pd(II) ions from aqueous solutions. 0.3 M thiourea in 0.1 M hydrochloric acid was found the most effective stripping phase in the transport of Pd(II) from membrane phase containing TOMATS. Separation of Pd(II) ions was also carried out from hydrochloric acid solution containing Pt(IV), Fe(III), Ni(II), and Mn(II). Pd(II) ions were preferably transported in the presence of these metal ions. The separation coefficients followed the order: S Pd/Pt < S Pd/Fe < S Pd/Ni < S Pd/Mn. [A336][TS] proved to be an excellent ion carrier for Pd(II) from hydrochloric acid solution. The results also showed that transport efficiency of the PIM was reproducible and it can be useful for the development of the simple and highly effective method of Pd(II) recovery from leach liquor of spent catalysts. 相似文献
93.
Differential scanning calorimetry (DSC) was used to investigate the thermal behavior and non-isothermal crystallization kinetics of the Fe67Nb5B28 metallic glasses prepared by melt-spinning method. DSC traces exhibit that the crystallization takes place through a single exothermic reaction, and it processes a good thermal stability in thermodynamics. The activation energies for nucleation and grain growth processes were calculated to be 536 ± 22 and 559 ± 20 kJ mol?1 by Kissinger equation, respectively, and 551 ± 24 and 574 ± 20 kJ mol?1 by Ozawa equation, respectively. It means that the grain growth process is more difficult than the nucleation process. The variation of local Avrami exponent n(x) with crystallized fraction x demonstrates that the crystallization mechanism varies at different stages. The n(x) is larger than 2.5 at the initial stage of 0 < x < 0.3, implying a mechanism of diffusion-controlled three-dimensional growth with increasing nucleation rate. The n(x) decreases from 2.5 to 1.5 in the range of 0.3 < x < 0.65, suggesting that the crystallization belongs to three-dimensional nucleation and grain growth with decreasing nucleation rate. And n(x) lies between 1.0 and 1.5 in the range of 0.65 < x < 0.95, indicating that the crystallization corresponds to the growth of particles with an appreciable initial volume. Low-temperature annealing corresponds to the precipitation of α-Fe, Fe2B, and Fe23B6 phases, and further annealing leads to the formation of α-Fe, Fe2B, and FeNbB phases. The magnetic properties in relation to microstructure change of the Fe67Nb5B28 metallic glasses are discussed. 相似文献
94.
We introduce a few functions related to convexity and smoothness of normed spaces. Those functions turn out to be moduli of
convexity or smoothness or play an intermediate role. We calculate the exact formulas for introduced functions in some classical
Banach spaces. An application to geometry of normed spaces is also indicated. 相似文献
95.
The magnetic behaviour of the coordination polymer [Co(C(3)H(3)N(2))(2)](n) has been investigated by magnetization and specific heat measurements. Low-field magnetic susceptibility shows the presence of two maxima at approximately 8 and 4 K (T(f)), which reflect short-range low-dimensional antiferromagnetic behaviour and the existence of a spin-glass-like state, respectively. The latter state was observed by magnetic irreversibility in both the zero-field cooled and field-cooled data, and was also confirmed by specific heat measurements. The magnetic specific heat (C(mag)) shows a lack of any long-range ordered peaks. Instead, a broad maximum near T(f) was observed in the C(mag)(T)/T-curve. Below T(f), the C(mag)(T) data follow the relation: C(mag)(T)/T = gamma + AT. We suggest that the competition of the antiferromagnetic (AF) intra-chain and the ferromagnetic (F) inter-chain interactions in a low-dimensional arrangement of magnetic Co(2+) ions can produce the spin-glass behaviour in the sample. The susceptibility data was analyzed in terms of a spin S = 3/2 Heisenberg linear-chain model with a small exchange energy and is consistent with the presence of both F and AF interactions. The splitting of the crystal field energy levels of the Co(2+) ions causes a Schottky-type specific heat anomaly of around 60 K. 相似文献
96.
Feature selection, while working with genomic data sets, is of particular interest, not only for classification (diagnostics) improvement, but also for the data interpretability. Application of the multivariate feature selection approaches allows an efficient reduction of data dimensionality, but as demonstrated in our study, sets of the selected variables depend on the objective function of the classifier. It is possible to select different subset of genes for classification due to the correlation of genes but their interpretation ought to be cautiously made. 相似文献
97.
Looking inside the human body fascinated mankind for thousands of years. Current diagnostic and therapy methods are often limited by inadequate sensitivity, specificity and spatial resolution. Raman imaging may bring revolution in monitoring of disease and treatment. The main advantage of Raman imaging is that it gives spatial information about various chemical constituents in defined cellular organelles in contrast to conventional methods (liquid chromatography/mass spectrometry, NMR, HPLC) that rely on bulk or fractionated analyses of extracted components. We demonstrated how Raman imaging can drive the progress on breast cancer just unimaginable a few years ago. We looked inside human breast ducts answering fundamental questions about location and distribution of various biochemical components inside the lumen, epithelial cells of the duct and the stroma around the duct during cancer development. We have identified Raman candidates as diagnostic markers for breast cancer prognosis: carotenoids, mammaglobin, palmitic acid and sphingomyelin as key molecular targets in ductal breast cancer in situ, and propose the molecular mechanisms linking oncogenes with lipid programming. 相似文献
98.
The paper presents a method for transforming a given sound and complete n-sequent proof system into an equivalent sound and complete system of ordinary sequents. The method is applicable to a large,
central class of (generalized) finite-valued logics with the language satisfying a certain minimal expressiveness condition.
The expressiveness condition decrees that the truth-value of any formula φ must be identifiable by determining whether certain
formulas uniformly constructed from φ have designated values or not. The transformation preserves the general structure of
proofs in the original calculus in a way ensuring preservation of the weak cut elimination theorem under the transformation.
The described transformation metod is illustrated on several concrete examples of many-valued logics, including a new application
to information sources logics. 相似文献
99.
Densities and kinematic viscosities have been measured for (1,2-ethanediol + 1-nonanol) over the temperature range from (298.15 to 313.15) K. The speeds of sound in those mixtures within the temperature range from (293.15 to 313.15) K have been measured as well. Using the measurement results, the molar volumes, isentropic compressibility coefficients, molar isentropic compressibilities, and the corresponding excess and deviation values (excess molar volumes, excess isentropic compressibility coefficients, excess molar isentropic compressibilities, differently defined deviations of the speed of sound, and dynamic viscosity deviations) were calculated. The excess Gibbs free energies estimated by the use of the UNIQUAC model are also reported. The excess molar volumes and Gibbs free energies are positive, whereas the compressibility excesses are s-shaped. The excess and deviation values are expressed by Redlich–Kister polynomials and discussed in terms of variations of the structure of the system caused by the participation of two different alcohol molecules in the dynamic intermolecular association process through hydrogen bonding. The effect of temperature is discussed. The predictive abilities of the McAllister equation for viscosities of the mixtures under test have also been examined. 相似文献
100.
Immunocompetent cells of earthworms (coelomocytes) contain adherent amoebocytes and large eleocytes (chloragocytes); the latter are filled with numerous granules. We have previously shown that eleocytes of several (but not all) earthworm species exhibit strong autofluorescence detectable by fluorescent microscopy and flow cytometry. In the present article, the molecular origin of eleocytes autofluorescence was elucidated in coelomocytes expelled via dorsal pores in the integument of Eisenia fetida subjected to electric shock (1 min at 4.5 V). Spectrofluorometry (excitation and emission spectra and fluorescence lifetime), together with HPLC analysis of coelomocyte suspensions and supernatants, indicated that riboflavin but not FMN (flavin mononucleotide) or FAD (flavin-adenine dinucleotide) is the main fluorophore responsible for eleocyte fluorescence in this species. Additionally, lipofuscins are suspected to participate in this phenomenon. 相似文献