全文获取类型
收费全文 | 200篇 |
免费 | 3篇 |
专业分类
化学 | 140篇 |
力学 | 1篇 |
数学 | 24篇 |
物理学 | 38篇 |
出版年
2023年 | 2篇 |
2021年 | 8篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 11篇 |
2012年 | 14篇 |
2011年 | 16篇 |
2010年 | 12篇 |
2009年 | 10篇 |
2008年 | 17篇 |
2007年 | 7篇 |
2006年 | 12篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 3篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1978年 | 1篇 |
1975年 | 2篇 |
1968年 | 1篇 |
1962年 | 1篇 |
1959年 | 1篇 |
1958年 | 3篇 |
1956年 | 2篇 |
1955年 | 1篇 |
排序方式: 共有203条查询结果,搜索用时 0 毫秒
91.
A series of lipophilic 2-substituted 5,7-di-tert-butylbenzoxazoles was prepared in average yields by the reaction of 3,5-di-tert-butyl-1,2-benzoquinone with amino acids and dipeptides bearing N-terminal glycine. Dipeptides having other N-terminal amino acids undergo oxidative deamination. 5,7-Di-tert-butylbenzoxazoles have shown activity against Mycobacterium tuberculosis and some nontuberculous strains where isoniazid has been inactive. Antifungal activity was mediocre. 相似文献
92.
Guilherme Figueira Alves Thalles Pedrosa Lisboa Lucas Vinícius de Faria Davi Marques de Farias Maria Auxiliadora Costa Matos Renato Camargo Matos 《Electroanalysis》2021,33(2):543-549
In this work, a new electrochemical sensor based on pencil graphite with interesting features, such as low cost (US$ 0.01 per electrode), ease manufacture, and portability was developed. The sensor showed an adequate manufacturing reproducibility with RSD <5.3 %. Under this electrochemical platform, ciprofloxacin underwent an irreversible oxidation process at 1.03 V, characterized by the diffusion of electroactive species. A simple method by square wave voltammetry (SWV) has been optimized for the determination of ciprofloxacin in pharmaceutical formulations using a pencil graphite electrode (PGE). The method showed satisfactory analytical performance, with a wide linear range (12 to 55 μmol L−1), low detection limit (5.6 μmol L−1), adequate precision (RSD <3.2 %), and accuracy with an average recovery of (102±15)%. Samples of pharmaceutical formulations were evaluated, obtaining levels of ciprofloxacin close to those established by the manufacturers. In addition, the samples were analyzed by liquid chromatography and there was no significant difference between the methods at the 95 % confidence level. In this sense, the method developed proved to be reliable and promising for the quality control of pharmaceutical formulations. 相似文献
93.
Zdeněk Kejík Tomáš Bříza Jarmila Králová Pavel Martásek Vladimír Král 《Analytical and bioanalytical chemistry》2010,398(5):1865-1870
It is well known that saccharides and their glycoconjugates can have an important influence on various serious pathologic
stages such as cancer. They can regulate tumor proliferation, invasion, hematogenous metastasis, and angiogenesis. These facts
clearly show the importance of cancer saccharide recognition. In medicine, sensor analysis is one of the best methods for
recognition and determination of biologically important analytes. The development and study of sensors for saccharide tumor
markers can open a new way for their detection. Therefore, this review is focused on recognition of saccharide-based cancer
markers by natural or synthetic selective ligands working as bio- and chemosensors. The design and application of these ligands
for cancer diagnosis is a useful direction of research. Moreover, it also opens the possibility of using these agents for
the targeted drug transport required for advanced anticancer therapy. 相似文献
94.
Copolymerizations of styrene with divinylbenzene (DVB) are carried out at low monomer concentrations in order to evaluate the incidence of cyclization reactions. The pendant double bond concentration in the synthesized polymers is measured using Fourier transform infrared spectroscopy. Reactions are carried out at monomer concentrations of 6% and 2% (v/v), DVB concentration in the range 15–80 wt% and temperatures in the range 60–90 °C. A previously developed model is used to interpret the results and analyze the cyclization effects. The predictions of the model accounting for cyclization reactions present a better agreement to the experimental data in comparison to predictions without cyclizations. Autoacceleration effects are observed for cases with higher DVB concentrations, in which the formation of highly entangled structures may have occurred. The model provides an estimate of 0.05 for the crosslink parameter (C P) and 130 s?1 for the rate constant of cyclization for the smallest sequence (three units) at 90 °C.
95.
Petra Snevajsova Lukas Tison Iveta Brozkova Jarmila Vytrasova Radovan Metelka Karel Vytras 《Electrochemistry communications》2010,12(1):106-109
An electrochemical biosensor for specific detection of DNA sequences from Aspergillus, a potentially aflatoxigenic fungus is reported. The detection technique was optimized using short DNA sequences, then applied for a 92-mer from the Aspergillus gene aflR that codes a biochemical pathway of aflatoxin B1 production.Voltammetric detection of the specific Aspergillus DNA sequence is based on hybridization of adsorbed target DNA with a biotinylated probe and subsequent binding with streptavidin alkaline phosphatase conjugate. Such modified electrode surface of carbon paste electrode (CPE) is incubated in a buffer with an electrochemically inactive substrate (1-naphthyl phosphate). Alkaline phosphatase converts 1-naphthyl phosphate into 1-naphthol, which is determined by the selected voltammetric technique. The optimized procedure provided good differentiation between complementary and noncomplementary probes and also between potentially aflatoxigenic and non-aflatoxigenic fungi of the genus Aspergillus. 相似文献
96.
97.
98.
Henrieta Stankovi
ov Anton Gplovský Margita Lcov Jarmila Chovancov Agnieszka Puchala 《Journal of heterocyclic chemistry》2006,43(4):843-848
Reaction of 6‐methyl‐4‐oxo‐4H‐[1]‐benzopyran‐3‐carboxaldehyde 1 with 5‐amino‐3‐methyl‐1‐phenylpyrazole 2 in alcoholic reaction media in the presence of 4‐toluenesulfonic acid as catalyst afforded 5‐(2‐hydroxy‐5‐methylbenzoyl)‐3‐methyl‐1‐phenyl‐1H‐pyrazolo[3,4‐b]pyridine 3 and 2‐methoxy‐6‐methyl‐3‐(3‐methyl‐1‐phenylpyrazol‐5‐ylaminomethylene)chroman‐4‐one 7 . We explain the mechanism of formation of both products on the basis of kinetic study of individual reaction steps. 相似文献
99.
Vinsova J Imramovsky A Buchta V Ceckova M Dolezal M Staud F Jampilek J Kaustova J 《Molecules (Basel, Switzerland)》2007,12(1):1-12
A new series of salicylanilide acetates was synthesized and evaluated for their in vitro antifungal and antituberculotic activity. Some of the evaluated compounds possessed comparable or better antifungal activity than a fluconazole standard. All these compounds exhibited very good potential and their in vitro activity against drug resistant and sensitive clinical isolates of Mycobacteria were found to be equivalent or better than a standard of isoniazide, a well-known first-line drug for tuberculosis treatment. 相似文献