全文获取类型
收费全文 | 143篇 |
免费 | 11篇 |
专业分类
化学 | 127篇 |
力学 | 2篇 |
数学 | 4篇 |
物理学 | 21篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 10篇 |
2011年 | 17篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 12篇 |
2007年 | 17篇 |
2006年 | 17篇 |
2005年 | 2篇 |
2004年 | 14篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1981年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有154条查询结果,搜索用时 15 毫秒
61.
62.
Preparation of dry powder inhalation by surface treatment of lactose carrier particles 总被引:4,自引:0,他引:4
Iida K Hayakawa Y Okamoto H Danjo K Leuenberger H 《Chemical & pharmaceutical bulletin》2003,51(1):1-5
An attempt was made to produce carrier particles for dry powder inhalations by the surface treatment of lactose particles with aqueous ethanol solution. Drug/carrier powder mixtures were prepared consisting of lactose carriers with different particle surface properties and micronized salbutamol sulfate. These powder mixtures were aerosolized by Spinhaler, and in vitro deposition properties of salbutamol sulfate were evaluated by twin impinger. The degree of adhesion between drug particles and carrier particles was determined by the ultracentrifuge separation method. In addition, the air jet sieve method was used to evaluate characteristics of the separation of drug particles from carrier particles in airflow. The average adhesion force (F50) between the surface-treated lactose carrier and drug particles was significantly lower than that of powder mixed with the untreated lactose carrier, indicating that the degree of separation (T50) of drug particles from carrier particles was improved when surface-treated lactose carrier was used. This resulted in an improvement of in vitro inhalation properties. 相似文献
63.
Shiotsuka M Yamamoto Y Okuno S Kitou M Nozaki K Onaka S 《Chemical communications (Cambridge, England)》2002,(6):590-591
An Ru(II)-Au(I)-Ru(II) triad has been synthesized from [Ru(bpy)2(3-ethynylphenanthroline)]2+ with Au(tht)Cl and characterized by spectroscopic means such as NMR and ESI-MS; the Ru(II)-Au(I)-Ru(II) triad shows an intense emission at 620 nm upon excitation at 360 nm, which suggests an efficient energy transfer from the Au site to Ru sites via extended pi-conjugation through the ethynyl units. 相似文献
64.
A highly sensitive method for measuring endogenous vitamin K1, menaquinone-4 (which is one of the K2 vitamins) and vitamin K1 2,3-epoxide in human plasma was developed, based on high-performance liquid chromatography with coulometric reduction and fluorimetric detection, following extraction from plasma and purification on a Sep-Pak silica cartridge. The detection limits of vitamin K1, menaquinone-4 and vitamin K1 2,3-epoxide were 5, 5 and 8 pg per injection for the standard substances and 30, 30 and 50 pg/ml in human plasma, respectively. 相似文献
65.
Organic emitting compounds that are based on π‐conjugated skeletons have emerged as promising next‐generation materials for application in optoelectronic devices. In this Minireview, recent advances in the development of organic emitters that irradiate room‐temperature phosphorescence and/or thermally activated delayed fluorescence with extraordinary luminescence properties, such as aggregation‐induced emission, mechanochromic luminescence, and circularly polarized luminescence, are discussed. 相似文献
66.
We consider the estimation of error variance in the analysis of experiments using two level orthogonal arrays. We address
the estimator which is the minimum of all the estimators which we obtain by pooling some sums of squares for factorial effects.
Under squared error loss, we discuss whether or not this estimator uniformly improves upon the best positive multiple of error
sum of squares. We show that when we have two factorial effects, we obtain uniform improvement. However, we show that when
we have more than two factorial effects, we cannot necessarily obtain uniform improvement. Further, the above results are
applied to the problem of estimating the smallest scale parameter of chi-square distributions. 相似文献
67.
Youhei Umino Hiroshi Nozaki Hiroshi Hamana Tadashi Narita 《Journal of polymer science. Part A, Polymer chemistry》2009,47(21):5698-5708
Novel fluorinated polymer synthesis with anionic polyaddition by double Michael addition reaction of 2‐trifluoromethylacrylate derivatives with ethyl cyanoacetate (ECA) was proposed. Diaddition product of ECA with phenyl 2‐trifluoromethylacrylate was yielded in high yield by the catalysis of sodium ethoxide in tetrahydrofuran at 60 °C. Sodium hydroxide catalyzed double Michael addition reaction also produced diaddition product in high yield. Novel anionic polyaddition of 1,4‐phenylene bis(2‐trifluoromethylacrylate) [CH2?C(CF3)COOC6H4OCOC(CF3)?CH2] (PBFA) with ECA afforded the polymer of 1.2 × 104 as the highest molecular weight. The isolated polymer gave the polymer of 2.8 × 104 as a molecular weight by the reaction of the isolated polymer with PBFA in the presence of sodium ethoxide; which proved that the polymer end groups were mainly ECA moieties. The reaction mechanism that the proton abstraction from ECA followed by the addition of 2trifluoromethylacrylate was proposed. The reaction of acetylacetone with PBFA was also examined to give the polymer of 7.6 × 103 as the highest molecular weight catalyzed by sodium hydroxide at room temperature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5698–5708, 2009 相似文献
68.
69.
Takeshi Sakano Dr. Jun‐ya Hasegawa Dr. Kenji Higashiguchi Prof. Kenji Matsuda 《化学:亚洲杂志》2012,7(2):394-399
The self‐assembled structure of alkoxy‐ and N‐alkylcarbamoyl‐substituted zinc–tetraphenylporphyrin at the liquid–highly oriented pyrolytic graphite (HOPG) interface was observed by using scanning tunneling microscopy. The alkoxy porphyrin showed a phase transition from face‐on to edge‐on ordering. The phase transition requires the close‐packed structure of alkoxy porphyrin. The chronological change of the ordering was traced to show the existence of several types of Ostwald ripening including two‐step phase transition from small edge‐on to face‐on and then further to edge‐on orderings. On the other hand, the N‐alkylcarbamoyl porphyrin showed persistent edge‐on ordering, and the ordering was analyzed by the Moiré pattern. Although the edge‐on ordering is observed only in the nonpolar solvent, the orderings have potential applications in the charge and energy transfer. 相似文献
70.
Mayumi Matsushita-Morita Hiroyuki Nakagawa Sawaki Tada Junichiro Marui Ryota Hattori Satoshi Suzuki Youhei Yamagata Hitoshi Amano Hiroki Ishida Michio Takeuchi Ken-Ichi Kusumoto 《Applied biochemistry and biotechnology》2013,171(1):145-164
β-Aminopeptidases exhibit both hydrolytic and aminolytic (peptide bond formation) activities and have only been reported in bacteria. We identified a gene encoding the β-aminopeptidase homolog from a genome database of the filamentous fungus Aspergillus oryzae. The gene was overexpressed in A. oryzae, and the resulting recombinant enzyme was purified. Apart from bacterial homologs [β-Ala-para-nitroanilide (pNA)], the enzyme preferred d-Leu-pNA and d-Phe-pNA as substrates. Therefore, we designated this gene as d-stereoselective aminopeptidase A (damA). The purified recombinant DamA was estimated to be a hexamer and was composed of two subunits with molecular masses of 29.5 and 11.5 kDa, respectively. Optimal hydrolytic activity of DamA toward d-Leu-pNA was observed at 50 °C and pH 8.0. The enzyme was stable up to 60 °C and from pH 4.0–11.0. DamA also exhibited aminolytic activity, producing d-Leu-d-Leu-NH2 from d-Leu-NH2 as a substrate. In the presence of 3.0 M NaCl, the amount of pNA liberated from d-Leu-pNA by DamA was 3.1-fold higher than that in the absence of NaCl. Thus, DamA is a halophilic enzyme. The enzyme was utilized to synthesize several hetero-dipeptides containing a d-amino acid at the N-terminus as well as physiologically active peptides. 相似文献