全文获取类型
收费全文 | 810篇 |
免费 | 21篇 |
国内免费 | 3篇 |
专业分类
化学 | 520篇 |
晶体学 | 7篇 |
力学 | 13篇 |
数学 | 111篇 |
物理学 | 183篇 |
出版年
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 11篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 21篇 |
2015年 | 24篇 |
2014年 | 18篇 |
2013年 | 49篇 |
2012年 | 47篇 |
2011年 | 50篇 |
2010年 | 25篇 |
2009年 | 28篇 |
2008年 | 35篇 |
2007年 | 47篇 |
2006年 | 43篇 |
2005年 | 25篇 |
2004年 | 23篇 |
2003年 | 30篇 |
2002年 | 28篇 |
2001年 | 14篇 |
2000年 | 23篇 |
1999年 | 17篇 |
1998年 | 9篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 11篇 |
1990年 | 8篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1975年 | 15篇 |
1974年 | 7篇 |
1973年 | 10篇 |
1972年 | 5篇 |
1969年 | 5篇 |
1968年 | 5篇 |
排序方式: 共有834条查询结果,搜索用时 78 毫秒
41.
42.
The environmental pollution is a central issue in the present industrial societies. Within that the air pollution and the removal of hazardous components of flue and exhaust gases are very much important.In this paper the target is to decrease of the NOx emission by means of a technology similar to that is used in the electrostatic precipitators. In most of the papers dealing with this technique cylindrical precipitator is used as a discharge chemical reactor, and fast rising electric discharges are applied for energizing the reactor. In the industry the over helming majority of the electrostatic precipitators are plate type one.In the cylindrical precipitator the discharge electrode is parallel with the gas flow, and the corona discharge filament is perpendicular to both of them. In the case of plate type industrial electrostatic precipitator the discharge electrodes are positioned vertically, and the flow of the flue gas is horizontal. Consequently, the discharge filaments are mainly perpendicular to both the flow and the discharge electrode.In cylindrical precipitator the decomposition of NOx is done in one filament very soon, but there is no chance to modify the byproducts with a new pulse, because the energization is the same for the whole length of the discharge electrode.In the present paper a cylindrical precipitator, a plate type precipitator with horizontal electrode, and a plate type precipitator with vertical electrode were tested. The total length of the discharge electrodes of all of the precipitators was the same.The results of the NOx decomposition were experimentally determined, and the differences between the precipitators were investigated. The cylindrical and the plate type precipitators with vertical electrodes had shown basically similar decomposition rate, while the plate type one with horizontal discharge electrode had proven inferior to the others. 相似文献
43.
In Korchmáros et al. (2018)one-factorizations of the complete graph are constructed for with any odd prime power such that either or . The arithmetic restriction is due to the fact that the vertices of in the construction are the points of a conic in the finite plane of order . Here we work on the Euclidean plane and describe an analogous construction where the role of is taken by a regular -gon. This allows us to remove the above constraints and construct one-factorizations of for every even . 相似文献
44.
A. Matsekh M. Inoue T. Kiss A. Ibi S. Miyata Y. Yamada T. Izumi 《Physica C: Superconductivity and its Applications》2010,470(20):1288-1291
Recent process optimization allows improving homogeneity and a significant increase of Jc in GdBa2Cu3O7-δ deposited on ion-beam assisted deposited MgO template (GdBCO/IBAD-MgO). We applied low-temperature laser scanning microscopy and laser scanning thermo-electric microscopy (LSTEM) to investigate local dissipation and defects simultaneously in recent GdBCO/IBAD-MgO coated conductor. By using high-resolution LSTEM, we could detect current blocking obstacles which are responsible for the large scale local dissipation. Data on the present GdBCO/IBAD-MgO coated conductors point out a significant reduction of current blocking obstacles compared to the previous process. We have shown the improvement of spatial homogeneity in the recent GdBCO/IBAD-MgO coated conductors. Current blocking obstacles are much less densely distributed as compared to previous YBCO/IBAD-GZO coated conductor. Obstacles larger than several micrometer significantly increase local dissipation whereas smaller defects do not influence it noticeably. 2D map of the phase delay component of the thermoelectric voltage lock-in signal is effective to analyze current blocking obstacles having action upon local dissipation. 相似文献
45.
Dr. Gert Kiss Dr. Nihan Çelebi‐Ölçüm Dr. Rocco Moretti Prof. Dr. David Baker Prof. Dr. Dr. K. N. Houk 《Angewandte Chemie (International ed. in English)》2013,52(22):5700-5725
Recent developments in computational chemistry and biology have come together in the “inside‐out” approach to enzyme engineering. Proteins have been designed to catalyze reactions not previously accelerated in nature. Some of these proteins fold and act as catalysts, but the success rate is still low. The achievements and limitations of the current technology are highlighted and contrasted to other protein engineering techniques. On its own, computational “inside‐out” design can lead to the production of catalytically active and selective proteins, but their kinetic performances fall short of natural enzymes. When combined with directed evolution, molecular dynamics simulations, and crowd‐sourced structure‐prediction approaches, however, computational designs can be significantly improved in terms of binding, turnover, and thermal stability. 相似文献
46.
András Ács Árpád Ferincz Anikó Kovács Beatrix Jancsek-Turóczi András Gelencsér Gyula Kiss Nora Kováts 《Central European Journal of Chemistry》2013,11(12):1954-1958
Diesel exhaust is one of the major sources of fine and ultrafine particulate matter in urban air. Toxicity of diesel-powered engine emissions has been quite widely assessed, however, much less information is available on their ecotoxicity. In our study the kinetic version of the Vibrio fischeri bioluminescence inhibition bioassay, based on the ISO 21338:2010 standard, was used to characterise the ecotoxicity of diesel-powered cars. The method is sensitive enough to test the ecotoxic effect of the emission of individual vehicles. In general, significant positive correlation was found between ecotoxicity (expressed as Toxic Unit /TU/values) and total carbon (TC) as well as between TU and polycyclic aromatic hydrocarbon (PAH) concentrations. 相似文献
47.
Gabriella Kervefors Kumar Bhaskar Pal Gergely L. Tolnai Mukul Mahanti Hakon Leffler Ulf J. Nilsson Berit Olofsson 《Helvetica chimica acta》2021,104(2):e2000220
β-Galactose derivatives have recently been reported to selectively inhibit galectin-3, and a library of O3-arylated galactosides with varying substitution patterns was designed to study such inhibitions further. The O3-arylated galactosides were synthesized using diaryliodonium salts under mild and transition metal free conditions, providing the target products in moderate to good yields. An O3-trifluoroethylated galactoside was also synthesized using iodonium salt chemistry. Azido-substituted products were subsequently transformed into the corresponding triazoles. After deprotection, a selection of galactoside derivatives were evaluated for inhibitory potencies against galectins-1, 3, 4 N (N-terminal domain), 4 C (C-terminal domain), 7, 8 N, 8 C, 9 N, and 9 C and one compound with promising affinity and selectivity for both the N- and C-terminal domain of galectin-9 was discovered. 相似文献
48.
Photocatalytic Water Oxidation by a Pyrochlore Oxide upon Irradiation with Visible Light: Rhodium Substitution Into Yttrium Titanate 下载免费PDF全文
Borbala Kiss Dr. Christophe Didier Timothy Johnson Dr. Troy D. Manning Dr. Matthew S. Dyer Dr. Alexander J. Cowan Dr. John B. Claridge Prof. James R. Darwent Prof. Matthew J. Rosseinsky 《Angewandte Chemie (International ed. in English)》2014,53(52):14480-14484
A stable visible‐light‐driven photocatalyst (λ≥450 nm) for water oxidation is reported. Rhodium substitution into the pyrochlore Y2Ti2O7 is demonstrated by monitoring Vegard′s law evolution of the unit‐cell parameters with changing rhodium content, to a maximum content of 3 % dopant. Substitution renders the solid solutions visible‐light active. The overall rate of oxygen evolution is comparable to WO3 but with superior light‐harvesting and surface‐area‐normalized turnover rates, making Y2Ti1.94Rh0.06O7 an excellent candidate for use in a Z‐scheme water‐splitting system. 相似文献
49.
50.
The development of a solid phase extraction (SPE) method is presented, which is capable of isolating approx. 60% of the water-soluble organic compounds from aerosol samples. The aqueous extracts of the filter samples were acidified then passed through an SPE column. Four silica-based and two polymeric reversed phase columns were tested and similar recoveries of the organic carbon were found. The isolated organic matter was nearly free from inorganic ions, which are major constituents of atmospheric aerosol. This fraction accounted for a major part of the UV absorption above 250 nm and fluorescence activity of the aerosol extract. The precision of the method was tested by performing three parallel sample preparations with Oasis HLB columns. It was found that the relative standard deviation of the carbon content of the isolated organic matter was better than 7%, which indicated the reliability of the method. In the atmospheric aerosol research the newly developed sample preparation method facilitates the physical and chemical characterisation of water-soluble organic compounds without the interference of inorganic constituents. 相似文献