全文获取类型
收费全文 | 2191篇 |
免费 | 15篇 |
国内免费 | 4篇 |
专业分类
化学 | 1459篇 |
晶体学 | 47篇 |
力学 | 85篇 |
数学 | 127篇 |
物理学 | 492篇 |
出版年
2022年 | 33篇 |
2021年 | 33篇 |
2020年 | 39篇 |
2019年 | 58篇 |
2018年 | 74篇 |
2017年 | 65篇 |
2016年 | 58篇 |
2015年 | 30篇 |
2014年 | 59篇 |
2013年 | 92篇 |
2012年 | 72篇 |
2011年 | 102篇 |
2010年 | 65篇 |
2009年 | 101篇 |
2008年 | 98篇 |
2007年 | 100篇 |
2006年 | 75篇 |
2005年 | 72篇 |
2004年 | 66篇 |
2003年 | 78篇 |
2002年 | 80篇 |
2001年 | 51篇 |
2000年 | 39篇 |
1999年 | 20篇 |
1998年 | 24篇 |
1997年 | 16篇 |
1996年 | 22篇 |
1995年 | 21篇 |
1994年 | 19篇 |
1993年 | 17篇 |
1992年 | 21篇 |
1991年 | 22篇 |
1990年 | 24篇 |
1989年 | 16篇 |
1987年 | 23篇 |
1986年 | 22篇 |
1985年 | 21篇 |
1984年 | 25篇 |
1982年 | 14篇 |
1978年 | 26篇 |
1977年 | 25篇 |
1976年 | 16篇 |
1975年 | 22篇 |
1974年 | 20篇 |
1973年 | 21篇 |
1972年 | 17篇 |
1971年 | 20篇 |
1970年 | 17篇 |
1968年 | 22篇 |
1967年 | 20篇 |
排序方式: 共有2210条查询结果,搜索用时 15 毫秒
51.
Bojidarka Ivanova Michael Spiteller 《Journal of inclusion phenomena and macrocyclic chemistry》2013,76(3-4):415-426
The analysis of heptachlorepoxides in gas- and condense phase of embedded in the organic matrixes analyte samples is highlighted. The electrospray ionization, matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS), nuclear magnetic resonance, Raman and CD spectroscopy as well as quantum chemical methods are used. The competitive formation of the variety of epoxides, strongly depending of the reaction conditions. Thus, the products of interaction of matrix-analyte matrixes under the UV–MALDI–MS experiment are comprehensively examinated. Nonetheless, that for heptachlor (HA) is known an epoxide, existing in two isomeric forms, i.e. A and B (exo- and endo-one), the study on the mechanism of the epoxidation of HA, showed formation of new epoxides C–F and an intermediate (I), characterizing with high stability, decreasing in the raw F > A > C > B > I > D > E. The epoxide D appeared enantiomer of the insecticide oxychlodran. The reported results on the pesticides, their metabolites and decomposition reactivity products contributed significantly to the field of analytical chemistry, providing possibility for elaboration of highly selective protocols for assessment of environmental contaminant issues. 相似文献
52.
Ivanova M. S. Vishnetskaya M. V. Tomskii K. O. Zainulin S. M. 《Kinetics and Catalysis》2022,63(4):418-421
Kinetics and Catalysis - It has been established that the reactions of sulfur dioxide oxidation and carbon dioxide conversion take place in aqueous suspensions of calcium fluoride at room... 相似文献
53.
Ivoilova A. V. Mikhal’chenko L. V. Tsmokalyuk A. N. Kozitsina A. N. Ivanova A. V. Rusinov V. L. 《Russian Chemical Bulletin》2021,70(6):1099-1108
Russian Chemical Bulletin - The results of studying electrochemical conversions of 7-R-3-X-1,2,4-triazolo[5,1-c][1,2,4]-triazin-4-ones (Triazavirin® and its derivatives) using cyclic... 相似文献
54.
I. V. Kumpanenko A. V. Roshchin N. A. Ivanova I. D. Epinat’ev A. M. Skryl’nikov M. V. Dyubanov T. N. Korneeva 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(5):740-747
The selective catalytic reduction (SCR) of nitrogen dioxide in an air flow modeling the exhaust gas from an internal combustion engine is studied. Granulated V2O5 (13.5%)–MnO2 (0.7–1.0%)/Al2O3 powder (AVK-10M catalyst) and ammonia injected into a SCR catalytic cell are used as a heterogeneous catalyst of NO2 reduction and a reducing agent, respectively. If the efficiency of NO2 removal is high enough and satisfies the requirements of the State Sanitary Standards for the maximum permissible concentrations of substances emitted into the atmosphere (\(MP{C_{N{O_2}}}\) = 0.085 mg/m3), the reducing agent (ammonia) is not completely consumed during SCR, so a considerable amount of NH3 can be released into the atmosphere. Therefore, a strict control of both NO2 and unreacted ammonia emissions is needed. The dependences of the concentrations of [NH3] and [NO2] on the [NH3]/[NO2] ratio for the model air flow passed through the AVK-10M granular heterogeneous catalyst are measured. It is found that the maximum degree of removal of NO2 from the air takes place at [NH3]/[NO2] = 1.3. In the conventional process, the concentration of [NO2] drop from 530.00 to 0.07 mg/m3, i.e., below the \(MP{C_{N{O_2}}}\). At the same time, the ammonia concentration increases to [NH3] = 3.4 mg/m3, which becomes 85 times the \(MP{C_{N{O_2}}}\), 0.04 mg/m3. To remove unreacted ammonia from air flows, we developed [P–(SO3 -)2 · Me2+] sulfocationites, where Me are the Cu and/or Ca ions, P is a styrene–divinylbenzene copolymer. It is shown that the concentration of ammonia passed through the adsorption cell filled with a freshly sulfocationite drops below \(MP{C_{N{H_3}}}\) = 0.04 mg/m3. The dependences of the dynamic exchange capacity (DEC) before ammonia breakthrough for the [P–(SO3 -)2 · Cu2+] delta-sulfocationite on the air flow rate, [NH3] concentration, and humidity are measured. The maximum value of the DEC, δ = 59.5 mg/cm3, is observed at an air flow velocity of 2.171 m/s, [NH3] = 0.0035 mg/L, and 75% humidity. To illustrate practical applications of the proposed improved SCR method, it is shown that a 3-L replaceable [P–(SO3 -)2 · Cu2+] sorbent cartridge in a SCR exhaust gas purifier for a car internal combustion engine does not need replacement more frequently than every 50000 km. 相似文献
55.
Results of the investigation into the interaction of internal waves and flows and the elaboration of a relevant mathematical model are reported. It is found in the field experiments that internal waves develop against the background of upwelling, which results in formation of jets causing intrusion velocity fluctuations. The mechanism and mathematical model of this process are proposed. A mathematical model of the suspended matter transport by jets with a wave-modulated trajectory is developed and verified. 相似文献
56.
Preparation of Stereoregular Isotactic Poly(mandelic acid) through Organocatalytic Ring‐Opening Polymerization of a Cyclic O‐Carboxyanhydride 下载免费PDF全文
Dr. Antoine Buchard Dr. David R. Carbery Prof. Matthew G. Davidson Dr. Petya K. Ivanova Dr. Ben J. Jeffery Dr. Gabriele I. Kociok‐Köhn Dr. John P. Lowe 《Angewandte Chemie (International ed. in English)》2014,53(50):13858-13861
Poly(mandelic acid) (PMA) is an aryl analogue of poly(lactic acid) (PLA) and a biodegradable analogue of polystyrene. The preparation of stereoregular PMA was realized using a pyridine/mandelic acid adduct (Py?MA) as an organocatalyst for the ring‐opening polymerization (ROP) of the cyclic O‐carboxyanhydride (manOCA). Polymers with a narrow polydispersity index and excellent molecular‐weight control were prepared at ambient temperature. These highly isotactic chiral polymers exhibit an enhancement of the glass‐transition temperature (Tg) of 15 °C compared to the racemic polymer, suggesting potential future application as high‐performance commodity and biomedical materials. 相似文献
57.
Pozdnyakov A. S. Ivanova A. A. Emel’yanov A. I. Prozorova G. F. 《Russian Chemical Bulletin》2020,69(4):715-720
Russian Chemical Bulletin - New polymer nanocomposites containing silver nanoparticles, stabilized by hydrophilic copolymers of 1-vinyl-1,2,4-triazole with vinylsulfonic acid sodium salt of... 相似文献
58.
T. I. Ivanova O. V. Frank-Kamenetskaya V. A. Drits M. Kastowsky H. Bradaczek 《Crystal Research and Technology》1995,30(3):367-374
The diffraction pattern simulation of four YBa2Cu3Ox single crystals with inhomogeneous distribution was successfully carried out on the base of the theory of X-ray diffraction by disordered interstratified structures. The specific feature of their two-component irregular mixed-layered structures is the total segregation of layers with various oxygen content that led to the formation of so-called intergrowth structures. The concentration of admixture layers varied from 10 to 40% while oxygen content difference within the crystal ranged from 0.5 to 0.3. In one of the crystals the fluctutations of layer heights corresponded to oxygen variation from 6.2 to 7.0. 相似文献
59.
60.
V. A. Kravets K. N. Orekhova M. A. Yagovkina E. V. Ivanova M. V. Zamoryanskaya 《Optics and Spectroscopy》2018,125(2):188-194
Spectra of Eu3+ in various dielectric matrices (Gd2O3:Eu3+, Y2O3:Eu3+, Eu2O3, and mSiO2/Gd2O3:Eu3+ mesoporous particles) are studied by local cathodoluminescence. The results allowed identification of the local environment of Er3+ ions in amorphous samples and detection of the monoclinic Eu2O3 phase impurity in samples with yttrium oxide. The cathodoluminescence spectra of chemically pure Y2O3, Eu2O3, and Gd2O3 are recorded. Conclusions about the structural features of the materials are made and confirmed by other methods (XRD and EPMA). 相似文献