全文获取类型
收费全文 | 2033篇 |
免费 | 97篇 |
国内免费 | 9篇 |
专业分类
化学 | 1697篇 |
晶体学 | 10篇 |
力学 | 27篇 |
数学 | 163篇 |
物理学 | 242篇 |
出版年
2023年 | 13篇 |
2022年 | 117篇 |
2021年 | 83篇 |
2020年 | 49篇 |
2019年 | 54篇 |
2018年 | 39篇 |
2017年 | 50篇 |
2016年 | 91篇 |
2015年 | 76篇 |
2014年 | 69篇 |
2013年 | 124篇 |
2012年 | 112篇 |
2011年 | 152篇 |
2010年 | 95篇 |
2009年 | 85篇 |
2008年 | 126篇 |
2007年 | 109篇 |
2006年 | 68篇 |
2005年 | 103篇 |
2004年 | 77篇 |
2003年 | 53篇 |
2002年 | 54篇 |
2001年 | 19篇 |
2000年 | 28篇 |
1999年 | 10篇 |
1998年 | 15篇 |
1997年 | 21篇 |
1996年 | 17篇 |
1995年 | 19篇 |
1994年 | 12篇 |
1993年 | 8篇 |
1992年 | 13篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 13篇 |
1988年 | 15篇 |
1987年 | 11篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1975年 | 6篇 |
1973年 | 9篇 |
1972年 | 5篇 |
1969年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有2139条查询结果,搜索用时 15 毫秒
871.
This review is written as a privilege of the work of Professor Mietek Jaroniec on surface phenomena, adsorption, chromatographic
separations, chemistry of conventional and ordered nanoporous materials.
The problems of the porous graphitic carbon (PGC) application in analytical field are presented. Special attention is paid
on possibilities of use PGC as a specific sorbent and packing material for selective isolation and analytes enrichment from
complex matrices by means of liquid-solid extraction techniques (SPE, SPME, MSPD) and as particular stationary phase in analytical
chromatographic columns. Surface and adsorption properties as well as a unique mechanism of retention on porous graphitized
carbon sorbents are described. As supplement the examples of application in biomedical and environmental area are added. 相似文献
872.
Stanke M Kedziera D Molski M Bubin S Barysz M Adamowicz L 《Physical review letters》2006,96(23):233002
Very accurate quantum mechanical calculations of the pure vibrational spectrum of the molecular ion are reported and compared with newly obtained pure vibrational transitions extracted from the available experimental data. The calculations are performed without assuming the Born-Oppenheimer approximation regarding separability of the nuclear and electronic motions and include the first order relativistic mass-velocity and Darwin corrections. For the two lowest transitions, whose experimental energies are established with the highest precision, the calculated and the experimental results show very good agreement. 相似文献
873.
Zhanna Evgrafova Bruno Voigt Dr. Monika Baumann Madlen Stephani Prof. Dr. Wolfgang H. Binder Prof. Dr. Jochen Balbach 《Chemphyschem》2019,20(2):236-240
Covalent conjugates between a synthetic polymer and a peptide hormone were used to probe the molecular extension of these macromolecules and how the polymer modifies the fibril formation of the hormone. NMR spectroscopy of 15N labeled parathyroid hormone (PTH) was employed to visualize the conformation of the conjugated synthetic polymer, triggered by small temperature changes via its lower critical solution temperature. A shroud-like polymer conformation dominated the molecular architecture of the conjugated chimeras. PTH readily forms amyloid fibrils, which is probably the physiological storage form of the hormone. The polyacrylate based polymers stimulated the nucleation processes of the peptide. 相似文献
874.
Sławomira Nowak Paweł Lisiecki Anna Tomaszczak-Nowak Ewa Grudzińska Monika Anna Olszewska 《Natural product research》2019,33(10):1535-1540
Essential oils from flowers and leaves of Grindelia integrifolia DC. were investigated for the first time in terms of chemical composition and antimicrobial activity. The GC-FID/MS analysis allowed for the identification of 58 and 72 volatiles, comprising 92.4 and 90.1% of the oils, respectively. The major components of the flower oil were α-pinene (34.9%) and limonene (13.1%), while myrcene (16.9%), spathulenol (12.3%), β-eudesmol (11.9%) and limonene (10.1%) dominated among the leaf volatiles. The antimicrobial activity, evaluated against 12 selected bacteria and fungus, was found moderate, with the strongest effect of both oils observed against C. albicans (MIC = MBC: 0.63 and 0.31 mg/mL for flower and leaf oil, respectively). 相似文献
875.
Östreicher Christiane Gensberger-Reigl Sabrina Pischetsrieder Monika 《Analytical and bioanalytical chemistry》2019,411(6):1273-1286
Analytical and Bioanalytical Chemistry - The Nrf2 signaling pathway is highly significant for redox homeostasis. Hence, nutrients and drugs activating Nrf2 can prevent oxidative stress-mediated... 相似文献
876.
Pol Karier Felix Ungeheuer Andreas Ahlers Felix Anderl Christian Wille Alois Fürstner 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):254-259
The new approach to the anticancer agent rhizoxin D described herein does not cohere with the conventional logic of metathesis, according to which macrocycles are best closed at a disubstituted olefinic site; rather, the trisubstituted C11?C12 alkene flanked by an allylic ‐OH group served as the pivot point for synthesis. This motif was attained in good yield and excellent selectivity by a sequence of alkyne metathesis, trans‐hydrostannation and cross coupling. Because the exact same substructure is prominently featured in numerous other natural products, the underpinning strategy, though unusual, might bear more general relevance. 相似文献
877.
In the first part of this paper a universal fluid velocity based algorithm for simulating hydraulic fracture with leak-off was created for a penny-shaped crack. The power-law rheological model of fluid was assumed and the final scheme was capable of tackling both the viscosity and toughness dominated regimes of crack propagation. The obtained solutions were shown to achieve a high level of accuracy. In this paper simple, accurate, semi-analytical approximations of the solution are provided for the zero leak-off case, for a wide range of values of the material toughness and parameters defining the fluid rheology. A comparison with other results available in the literature is undertaken. 相似文献
878.
Z.?Machala I.?Jedlovsky L.?Chládeková B.?Pongrác D.?Giertl M.?Janda L.??ikurová P.?Pol?ic 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):195-204
Three types of DC electrical discharges in atmospheric air (streamer corona, transient spark and glow discharge) were tested
for bio-decontamination of bacteria and yeasts in water solution, and spores on surfaces. Static vs. flowing treatment of
contaminated water were compared, in the latter the flowing water either covered the grounded electrode or passed through
the high voltage needle electrode. The bacteria were killed most efficiently in the flowing regime by transient spark. Streamer
corona was efficient when the treated medium flew through the active corona region. The spores on plastic foil and paper surfaces
were successfully inactivated by negative corona. The microbes were handled and their population evaluated by standard microbiology
cultivation procedures. The emission spectroscopy of the discharges and TBARS (thiobarbituric acid reactive substances) absorption
spectrometric detection of the products of lipid peroxidation of bacterial cell membranes indicated a major role of radicals
and reactive oxygen species among the bio-decontamination mechanisms. 相似文献
879.
Tomas Jasenovec Dominika Radosinska Marta Kollarova Peter Balis Kristina Ferenczyova Barbora Kalocayova Monika Bartekova Lubomira Tothova Jana Radosinska 《Molecules (Basel, Switzerland)》2021,26(16)
Diabetes mellitus is characterized by tissue oxidative damage and impaired microcirculation, as well as worsened erythrocyte properties. Measurements of erythrocyte deformability together with determination of nitric oxide (NO) production and osmotic resistance were used for the characterization of erythrocyte functionality in lean (control) and obese Zucker diabetic fatty (ZDF) rats of two age categories. Obese ZDF rats correspond to prediabetic (younger) and diabetic (older) animals. As antioxidants were suggested to protect erythrocytes, we also investigated the potential effect of quercetin (20 mg/kg/day for 6 weeks). Erythrocyte deformability was determined by the filtration method and NO production using DAF-2DA fluorescence. For erythrocyte osmotic resistance, we used hemolytic assay. Erythrocyte deformability and NO production deteriorated during aging—both were lower in older ZDF rats than in younger ones. Three-way ANOVA indicates improved erythrocyte deformability after quercetin treatment in older obese ZDF rats only, as it was not modified or deteriorated in both (lean and obese) younger and older lean animals. NO production by erythrocytes increased post treatment in all experimental groups. Our study indicates the potential benefit of quercetin treatment on erythrocyte properties in condition of diabetes mellitus. In addition, our results suggest potential age-dependency of quercetin effects in diabetes that deserve additional research. 相似文献
880.
M. P. Danilaev E. A. Bogoslov Yu. E. Pol’skii A. R. Nasybullin M. S. Pudovkin A. R. Khadiev 《Technical Physics》2017,62(2):255-260
The influence of growth conditions on the carbon dendrite structure has been investigated. The threshold values of the ratio between electron temperature T e and kinetic temperature T of the gas near a needle electrode and of the discharge current density, which are necessary for dendritic growth, have been determined. It has been shown that the hexagonal structure of submicron carbon particles arises when a number of hydrocarbons are used to synthesize dendrites. It has been found that the degree of order in the carbon structure can be controlled by applying external actions at the stage of graphite particle nucleation. The characteristic frequencies of inertial actions that may be energetically appropriate must exceed 10 kHz. 相似文献