全文获取类型
收费全文 | 240篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 197篇 |
晶体学 | 8篇 |
力学 | 5篇 |
数学 | 8篇 |
物理学 | 25篇 |
出版年
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 6篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2014年 | 8篇 |
2013年 | 14篇 |
2012年 | 3篇 |
2011年 | 10篇 |
2010年 | 8篇 |
2009年 | 3篇 |
2008年 | 17篇 |
2007年 | 6篇 |
2006年 | 11篇 |
2005年 | 17篇 |
2004年 | 13篇 |
2003年 | 9篇 |
2002年 | 5篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 11篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1958年 | 1篇 |
1956年 | 1篇 |
1955年 | 2篇 |
1954年 | 1篇 |
1953年 | 1篇 |
1937年 | 2篇 |
1934年 | 2篇 |
1898年 | 1篇 |
排序方式: 共有243条查询结果,搜索用时 31 毫秒
41.
Giorgio Peyronel Anna Pignedoli Wanda Malavasi 《Journal of chemical crystallography》1982,12(6):481-488
The crystal and molecular structure of 3,5-diamino-1,2,4-dithiazolium bromide has been refined from three-dimensional counter data (856 reflections) by least-squares methods, anisotropically for the nonhydrogen and isotropically for the hydrogen atoms, to a finalR=0.036:a=9.948(1),b=12.731(1),c=5.098(1) Å, B=98.70(1)° at 18°C,Z=4,P21/n. The S-S (2.075 Å) distance is intermediate between those of the thiouret hydrochloride and hydroiodide. The C-N(terminal) and C-N(bridging) distances are close to their average value (1.322 Å) within their standard deviations. Thev(NH2) and (NH2) frequencies of the thiouret hydrohalides are close to those of dithiobiuret while thev(NH) and (NH) bands are, as expected, absent. Thev(CN) andv(CS) bands are shifted to higher and lower frequencies, respectively, while a newv(SS) broad band is observed in the 430–410 cm–1 region. 相似文献
42.
Andreas Knnecke Eberhard Lippmann Jacek Mlochowski Wanda Sliwa 《Magnetic resonance in chemistry : MRC》1979,12(12):696-701
The 13C chemical shifts of eleven isomeric diazaphenathrenes (1.5-? 1.10-, 2.7-, 4.5-? 4.7-, and 5.6-DAP) have been determined and iteratively assigned by means of comparison with suitable model compounds. The data obtained (132 points) were used to test the relationship between 13C chemical shifts and HMO charge densities. The best correlation with a standard deviation S(E) = 4.8 ppm was found for the chemical shifts, relative to phenanthrene, of tertiary carbons. The different slopes for correlations of tertiary and quarternary carbons (275–300 vs 540–550 ppm/electron) are most probably due to different ΔE values for both types of carbons. 相似文献
43.
Precision determination of deuterium (deuterium oxide) in aqueous mixtures were made by a pyenometer method over the range of 1 to 99 atom-% deuterium. The average deviation was ± 0.02 atom-%, deuterium.Absolute values of high-deuterium content samples are obtained by reference to a sample of high deuterium oxide content (> 99 atom-% deuterium) which has been measured by a mass spectrometer, instead of to distilled water. Matched-standards are also provided for intermediate-content (25–75 atom-%) deuterium oxide samples. 相似文献
44.
Walczak W Pipalia NH Soni M Faruqi AF Ralph H Maxfield FR Webb BL 《Combinatorial chemistry & high throughput screening》2006,9(9):711-718
The conversion of the genomic information produced by the recent sequencing projects into a comprehensive understanding of the human proteome has yet to occur. A new technology that represents a potential bridge between genomics and proteomics is reverse transfection. Reverse transfection cell microarrays are produced by overlaying cDNA arrays with mammalian cells, generating localized clusters of transfected cells with each cluster overexpressing a unique protein. This miniaturized cell-based microarray format affords parallel functional analysis of thousands of cDNA constructs in a high throughput format. In this report we document the development of a co-transfection methodology for reverse transfection applications. The demonstrated high co-transfection efficiency with a "marker" plasmid encoding for GFP enables the identification of transfected cells and eliminates the need for epitope-tagged constructs in cell-based high throughput screening applications using reverse transfection. This co-transfection method was used to study in parallel the structure/function of multiple versions of the v-Src protein using automated fluorescence microscopy. The wild-type v-Src protein and four mutants having insertions or deletions in the SH2 or SH3 domains displayed high levels of tyrosine kinase activity in HEK293T cells. Three other mutated v-Src proteins, including a kinase-dead version, were shown to be defective for tyrosine kinase activity. This reverse co-transfection approach is applicable for high throughput screening of both cDNA libraries and positional scanning recombinant protein libraries. 相似文献
45.
Adamson P Andreopoulos C Arms KE Armstrong R Auty DJ Ayres DS Baller B Barr G Barrett WL Becker BR Belias A Bernstein RH Bhattacharya D Bishai M Blake A Bock GJ Boehm J Boehnlein DJ Bogert D Bower C Buckley-Geer E Cavanaugh S Chapman JD Cherdack D Childress S Choudhary BC Coleman SJ Culling AJ de Jong JK Diwan MV Dorman M Dytman SA Escobar CO Evans JJ Falk Harris E Feldman GJ Frohne MV Gallagher HR Goodman MC Gouffon P Gran R Grashorn EW Grossman N Grzelak K Habig A Harris D Harris PG 《Physical review letters》2008,101(15):151601
A search for a sidereal modulation in the MINOS near detector neutrino data was performed. If present, this signature could be a consequence of Lorentz and CPT violation as predicted by the effective field theory called the standard-model extension. No evidence for a sidereal signal in the data set was found, implying that there is no significant change in neutrino propagation that depends on the direction of the neutrino beam in a sun-centered inertial frame. Upper limits on the magnitudes of the Lorentz and CPT violating terms in the standard-model extension lie between 10(-4) and 10(-2) of the maximum expected, assuming a suppression of these signatures by a factor of 10(-17). 相似文献
46.
Joanna Brzeska Magda Morawska Aleksandra Heimowska Wanda Sikorska Wojciech Wałach Anna Hercog Marek Kowalczuk Maria Rutkowska 《Chemical Papers》2018,72(5):1249-1256
The surface morphology and thermal properties of polyurethanes can be correlated to their chemical composition. The hydrophilicity, surface morphology, and thermal properties of polyurethanes (differed in soft segments and in linear/cross-linked structure) were investigated. The influence of poly([R,S]-3-hydroxybutyrate) presence in soft segments and blending of polyurethane with polylactide on surface topography were also estimated. The linear polyurethanes (partially crystalline) had the granular surface, whereas the surface of cross-linked polyurethanes (almost amorphous) was smooth. Round aggregates of polylactide un-uniformly distributed in matrix of polyurethane were clearly visible. It was concluded that some modification of soft segment (by mixing of poly([R,S]-3-hydroxybutyrate) with different polydiols and polytriol) and blending of polyurethanes with small amount of polylactide influence on crystallinity and surface topography of obtained polyurethanes. 相似文献
47.
Tomer Rosen Wanda Navarra Prof. Vincenzo Venditto Prof. Moshe Kol 《Angewandte Chemie (International ed. in English)》2018,57(24):7191-7195
A magnesium complex of the type {ONNN}Mg‐HMDS wherein {ONNN} is a sequential tetradentate monoanionic ligand is introduced. In the presence of an alcohol initiator this complex catalyzes the living and immortal homopolymerization of the lactide enantiomers and ?‐caprolactone at room‐temperature with exceptionally high activities, as well as the precise block copolymerization of these monomers in a one‐pot synthesis by sequential monomer addition. Copolymers of unprecedented microstructures such as the PCL‐b‐PLLA‐b‐PDLA and PDLA‐b‐PLLA‐b‐PCL‐b‐PLLA‐b‐PDLA block–stereoblock microstructures that feature unique thermal properties are readily accessed. 相似文献
48.
Herman O. Desseyn Antonio C. Fabretti Wanda Malavasi 《Journal of chemical crystallography》1990,20(4):355-362
The title compound (C6H10CdN12S2) was prepared and characterized by means of X-ray, Raman, and IR measurements. The crystals are orthorhombic:Pbcn, (No. 60),a=9.558(2),b=9.491(2),c=15.898(2) Å,Z=4. The structure was solved by the heavy-atom method, and least-squares refinement of structural parameters led toR=0.021 (R
w
=0.020) for 863 independent reflections. The compound exhibits two-dimensional Cd(II) networks, with the 1,2,4-triazole molecule acting as a bidentate bridging ligand. The structure consists of centrosymmetric units, in which the cadmium atoms are coordinated in distorted octahedral geometries by six nitrogen atoms. Each cadmium atom is linked by four 1,2,4-triazole molecules, and two thiocyanate ions complete the octahedral coordination around the metal. Each 1,2,4-triazole molecule bridges two cadmium atoms. The NH and NH2 groups of the guanazole unit are involved in intermolecular hydrogen bonds. Infrared and Raman bands are diagnostic of the coordination environments around the metal atoms. 相似文献
49.
Wanda Mczka Anna Duda-Madej Aleksandra Grny Magorzata Grabarczyk Katarzyna Wiska 《Molecules (Basel, Switzerland)》2021,26(16)
One of the primary reasons for the search for new antimicrobial agents is the increasing and spreading resistance of microorganisms to previously used drugs. This is particularly important in the case of rapidly progressing infections that require the rapid administration of an appropriately selected antibiotic. However, along with the administration of antibiotics, complications in the disease-weakened body may arise in the form of systemic mycoses, viral infections, and protozoan infections. Therefore, there is an increasing interest among researchers focusing on the use of naturally occurring terpenic compounds in stand-alone or combined therapies with antibiotics. In this publication, the aim of our work is to present the results of a literature review on the antimicrobial activity of eucalyptol. 相似文献
50.
Wanda Sikorska Piotr Dacko Michał Sobota Joanna Rydz Marta Musioł Marek Kowalczuk 《Macromolecular Symposia》2008,272(1):132-135
Summary: Polyesters produced from renewable resources and susceptible to hydrolysis under the industrial composting conditions offer ecological advantages as compared to thermoplastics polymers and elastomers produced from fossil carbon sources. In this paper the degradation behaviour of polymer compositions of BTA, PLA and a-PHB in natural environment of industrial composting pile, consisting of leaves - 40%, branches - 30% and grass - 30%, have been presented. The extend of degradation was monitored by macroscopic observations of sample surfaces, changes of molecular weight, polydispersity and composition of the tested materials and their weight loss. 相似文献