全文获取类型
收费全文 | 421篇 |
免费 | 28篇 |
专业分类
449篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 6篇 |
2021年 | 17篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 12篇 |
2017年 | 18篇 |
2016年 | 19篇 |
2015年 | 14篇 |
2014年 | 24篇 |
2013年 | 34篇 |
2012年 | 43篇 |
2011年 | 30篇 |
2010年 | 24篇 |
2009年 | 21篇 |
2008年 | 15篇 |
2007年 | 33篇 |
2006年 | 19篇 |
2005年 | 12篇 |
2004年 | 17篇 |
2003年 | 19篇 |
2002年 | 15篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有449条查询结果,搜索用时 0 毫秒
51.
Bupranolol is a promising candidate for transdermal drug delivery system (TDDS) development. The effect of permeation enhancers on the in vivo delivery and beta-blocking effect of reservoir type TDDS was studied in comparison with intravenous BPL in rabbits. The beta-blocking effect was quantified by measuring the inhibition of isoprenaline induced tachycardia in rabbits after BPL administration via transdermal and intravenous routes. The reservoir type TDDS containing a hydroxypropyl cellulose gel and polyethylene membrane was used as a control device. In comparison, the TDDS containing skin penetration enhancers, either 2-pyrrolidone or partially methylated beta cyclodextrin (PMbetaCD) were evaluated. The control device (no enhancer) produced about 52% inhibition of isoprenaline induced tachycardia at 2 h and the effect continued over 24 h application period, however, the devices with 2-pyrolidone or PMbetaCD produced about 85% inhibition of isoprenaline induced tachycardia at 3 h and the same effect continued over 24 h application period. Likewise, the AUC of these devices were significantly higher than that of control device. The intravenous bupranolol showed rapid decline in the pharmacodynamic effect with time indicating its rapid elimination. The in vivo delivery of bupranolol (as estimated by a mass balance study) from the devices made with pyrolidone or PMbetaCD was 3-fold higher than that of control. The results of this study strongly suggest that the penetration enhancers in the TDDS increased the in vivo delivery of BPL, thereby increased the beta-blocking activity of BPL by 50-60% higher than control, enabling the reduction of the TDDS patch size, accordingly. 相似文献
52.
Syed Bilal Jilani Siva Sai Krishna Venigalla Anu Jose Mattam Chandra Dev Syed Shams Yazdani 《Journal of industrial microbiology & biotechnology》2017,44(9):1375-1384
E. coli has the ability to ferment both C5 and C6 sugars and produce mixture of acids along with small amount of ethanol. In our previous study, we reported the construction of an ethanologenic E. coli strain by modulating flux through the endogenous pathways. In the current study, we made further changes in the strain to make the overall process industry friendly; the changes being (1) removal of plasmid, (2) use of low-cost defined medium, and (3) improvement in consumption rate of both C5 and C6 sugars. We first constructed a plasmid-free strain SSY13 and passaged it on AM1–xylose minimal medium plate for 150 days. Further passaging was done for 56 days in liquid AM1 medium containing either glucose or xylose on alternate days. We observed an increase in specific growth rate and carbon utilization rate with increase in passage numbers until 42 days for both glucose and xylose. The 42nd day passaged strain SSK42 fermented 113 g/L xylose in AM1 minimal medium and produced 51.1 g/L ethanol in 72 h at 89% of maximum theoretical yield with ethanol productivity of 1.4 g/L/h during 24–48 h of fermentation. The ethanol titer, yield and productivity were 49, 40 and 36% higher, respectively, for SSK42 as compared to unevolved SSY13 strain. 相似文献
53.
Davis GD Masilamoni JG Arul V Kumar MS Baraneedharan U Paul SF Sakthivelu IV Jesudason EP Jayakumar R 《Cell biology and toxicology》2009,25(4):331-340
During the course of cancer radiation treatment, normal skin invariably suffers from the cytotoxic effects of γ-radiation
and reactive oxygen species (ROS), which are generated from the interaction between radiation and the water molecules in cells.
The present study was designed to investigate the radioprotective role of α-lipoic acid (LA), an antioxidant on murine skin
fibroblasts exposed to a single dose of 2, 4, 6, or 8Gy γ-radiation. Irradiation of fibroblasts significantly increased ROS,
nitric oxide, and lipid peroxidation (P < 0.001); all of these factors substantially decreased with 100 μM LA treatment. Hydroxyl radical (OH⋅) production from 8Gy irradiated fibroblasts was measured directly by electron spin resonance using spin-trapping techniques.
LA was found to inhibit OH⋅ production at 100-μM concentrations. Dose-dependent depletion of antioxidants, such as catalase and glutathione reductase,
was observed in irradiated fibroblasts (P < 0.001), along with increased superoxide dismutase (P < 0.001). LA treatment restored antioxidant levels. Concentration of the pro-inflammatory cytokine IL-1β was significantly
reduced in irradiated fibroblasts when treated with LA. MTT and lactate dehydrogenase assays demonstrated that LA treatment
reduced cell injury and protected cells against irradiation-induced cytotoxicity. Thus, we conclude that results are encouraging
and need further experiments to demonstrate a possible benefit in cancer patients and the reduction of harmful effects of
radiation therapy. 相似文献
54.
55.
Kasthuri Kannayiram Vidhya Rekha Umapathy Y Chamundeswari JH Fathima Ramajayam Govindan Chella Perumal Palanisamy Vishnu Priya Veeraraghavan Selvaraj Jayaraman Ponnulakshmi Rajagopal 《Bioinformation》2022,18(3):80
Diabetes mellitus is a group of metabolic disorders that has risen to become the third most common cause in humans in recent years. The development of new bioactive substances from natural sources is a relatively new area. Flavonoids are believed to have a variety of beneficial properties in nature, including anti-inflammatory, antimicrobial, anticancer, antioxidant, neuroprotective, and anti-HIV properties. 15 naturally occurring flavonoids docked with the selected target aldose reductase. We report the optimal binding of Acumitin, Agathisflavone, Agehoustin B, and alpha-Toxicarol with aldose reductase for further consideration in drug discovery for T2DM. 相似文献
56.
G-protein coupled receptors (GPCRs) are found to be attractive drug targets for the treatment of various neuronal diseases. Allosteric modulators have their role in enhancing or suppressing the effect of glutamate on mGluRs. Structure of mGluR1 was generated with the help of Modeller software by considering human B2-adrenergic GPCR protein as template. Structure of various already known drug molecules were used for similarity search in the ZINC database and a large number of similar molecules were obtained, than filtering of these molecules were done by applying drug features. Molecules were screened by Molegro Virtual Docking program and numbers of novel molecules were generated by using LigBuilder software. Finally 16 novel drug candidates were selected, which were showing better results than the seed molecule and previously known modulators. These results will help in designing and synthesis of better drugs against diseases like Epilepsy and Parkinson's. 相似文献
57.
Nair Radhika V. Dileep Kottilil Gummaluri Venkata Siva Vijayan C. 《Plasmonics (Norwell, Mass.)》2017,12(5):1649-1656
Plasmonics - We present a systematic computational study on the optical properties of a new composite structure based on ZnS–metal core-shell particles, which can find applications in light... 相似文献
58.
59.
A series of quinolone derivatives, containing different heterocyclic amines were prepared. Synthesized compounds were evaluated for their in vitro antimicrobial activities against two Gram-positive bacteria, three Gram-negative bacteria as well as four fungi. All the derivatives showed good activity towards Gram-positive bacteria and less activity towards Gram-negative bacteria. They also showed moderate to comparable activity against Aspergillus niger and Candida albicans and low to moderate antifungal activity against Aspergillus fumigatus and Aspergillus flavus. 相似文献
60.
The effect of a number of compounds structurally related to glutamic acid and other nitrogenous compounds on the composition of three forms of glutamine synthetase (GS) inRhizobium phaseoli has been examined in detail. Amino acids like glutamic acid, glutamine, and a fixed source of nitrogen like ammonium chloride did not alter the relative glutamine synthetase composition.l-Methioninedl-sulfoximine (MSX), a glutamate analogue, significantly repressed the synthesis of GSIII to a greater extent.,N-oxalyl,-diaminopropionic acid (ODAP), another glutamate analogue, selectively stimulated the synthesis of GSII, and the effect of ODAP on GSII synthesis was greatly enhanced in the presence of ethylenediamine or ammonium chloride. Ethylenediamine itself caused a predominant synthesis of GSIII.-Cyanoalanine-grownR. phaseoli did not synthesize GSI. The synthesis of the three different glutamine synthetases can thus be differentially modulated. 相似文献