全文获取类型
收费全文 | 81篇 |
免费 | 1篇 |
专业分类
82篇 |
出版年
2023年 | 1篇 |
2021年 | 1篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 3篇 |
2012年 | 4篇 |
2010年 | 8篇 |
2009年 | 3篇 |
2008年 | 4篇 |
2007年 | 4篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2004年 | 2篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有82条查询结果,搜索用时 15 毫秒
31.
The ultrastructure of neonatal rat heart cells in suspension and in tissue culture after freezing at optimal, suboptimal, and supraoptimal cooling rates with 2.5, 5, 7.5, and 10% DMSO was investigated. The effect of DMSO treatment only on the structure of the cells was also studied. A comparison was made with the survival in culture.Without freezing, increasing DMSO concentrations caused an increase of morphological damage, correlating with a decrease of the survival in culture. With 2.5% DMSO there was no difference with untreated cells. At higher DMSO concentrations, the ultrastructural damage increased from spaces between cell membrane and cytoplasm at 5% DMSO to interrupted cell membranes, swollen or destroyed mitochondria, and nuclei with clumped chromatin at 10% DMSO.After freezing at optimal or nonoptimal cooling rates with 5 or 7.5% DMSO, the ultrastructure correlated well with the survival. After freezing with 2.5 or 10% DMSO at optimal or nonoptimal cooling rates, differences in survival were found, which were not reflected in the ultrastructure of the cell. After 8 days of culturing, cells which were frozen at all the different cooling rates and DMSO concentrations appeared to have a normal structure. 相似文献
32.
Retinopathy of prematurity (ROP) is a vasoproliferative disorder that occurs in premature infants and may lead to permanent visual impairment. We investigated both the possible protective role of N-acetyl cysteine (NAC) for preventing ROP and the role of IGF-1 in the disorder. Forty-five newborn rats were divided into three groups. Group 1 was raised in room air as controls. Group 2 was exposed to 60% oxygen for 14 days after birth, then transferred to room air. Group 3 was exposed to the same conditions as group 2, but received intraperitoneal injections of NAC on postnatal days 7–17. After 35 days, both eyes of all rats were processed for histology. Some sections were stained with hematoxylin and eosin to assess structural changes and other sections were immunostained to determine the location of IGF-1. Frozen sections also were prepared and stained for adenosine triphosphatase to detect retinal blood vessels. Compared to the controls, more blood vessels, many of which were abnormal, and increased IGF-1 expression were observed in group 2. In group 3, abnormal blood vessels and IGF-1 expression were less evident. NAC appeared to be an effective vascular-protective agent for ROP by decreasing IGF-1 expression. 相似文献
33.
Niels H Chavannes Juanita HJ Vernooy Tjard RJ Schermer Jan A Jacobs Mieke A Dentener Chris van Weel Onno CP van Schayck Emiel FM Wouters 《BMC pulmonary medicine》2006,6(1):1-7
Background
Although both smoking and respiratory complaints are very common, tools to improve diagnostic accuracy are scarce in primary care. This study aimed to reveal what inflammatory patterns prevail in clinically established diagnosis groups, and what factors are associated with eosinophilia.Method
Induced sputum and blood plasma of 59 primary care patients with COPD (n = 17), asthma (n = 11), chronic bronchitis (CB, n = 14) and smokers with no respiratory complaints ('healthy smokers', n = 17) were collected, as well as lung function, smoking history and clinical work-up. Patterns of inflammatory markers per clinical diagnosis and factors associated with eosinophilia were analyzed by multiple regression analyses, the differences expressed in odds ratios (OR) with 95% confidence intervals.Results
Multivariately, COPD was significantly associated with raised plasma-LBP (OR 1.2 [1.04–1.37]) and sTNF-R55 in sputum (OR 1.01 [1.001–1.01]), while HS expressed significantly lowered plasma-LBP (OR 0.8 [0.72–0.95]). Asthma was characterized by higher sputum eosinophilic counts (OR 1.3 [1.05–1.54]), while CB showed a significantly higher proportion of sputum lymphocytic counts (OR 1.5 [1.12–1.9]). Sputum eosinophilia was significantly associated with reversibility after adjusting for smoking, lung function, age, gender and allergy.Conclusion
Patterns of inflammatory markers in a panel of blood plasma and sputum cells and mediators were discernable in clinical diagnosis groups of respiratory disease. COPD and so-called healthy smokers showed consistent opposite associations with plasma LBP, while chronic bronchitics showed relatively predominant lymphocytic inflammation compared to other diagnosis groups. Only sputum eosinophilia remained significantly associated with reversibility across the spectrum of respiratory disease in smokers with airway complaints. 相似文献34.
Alink GM Quik JT Penders EJ Spenkelink A Rotteveel SG Maas JL Hoogenboezem W 《Mutation research》2007,631(2):93-100
Surface water used for drinking-water preparation requires continuous monitoring for the presence of toxic compounds. For monitoring of genotoxic compounds fish models have been developed, such as the Eastern mudminnow (Umbra pygmaea L.) because of its clearly visible 22 meta-centric chromosomes. It was demonstrated in the late seventies that Rhine water was able to induce chromosome aberrations and sister chromatid exchange in this fish species. Although in vitro mutagenicity studies of the RIWA (Rhine Water Works, The Netherlands) have shown that the genotoxicity of the river Rhine steadily decreased during the last decades, there is still concern about the presence of some residual mutagenicity. In addition, in most studies the water samples have been tested only in in vitro test systems such as the Salmonella-microsome test. For this reason, and in order to be able to make a comparison with the water quality 27 years ago, a study was performed with the same experimental design as before in order to measure the effect of Rhine water on the induction of SCE in the Eastern mudminnow. As a new test system the single cell gel electrophoresis assay (Comet assay) was performed. Fish were exposed to Rhine water or to groundwater for 3 and 11 days in flow-through aquaria. Fish exposed for 11 days to Rhine water had a significantly higher number of SCE and an increased comet tail-length compared with control fish exposed to groundwater. After exposure for three days to Rhine water there was no difference in SCE and a slightly increased comet tail-length compared with the control. It was concluded that genotoxins are still present in the river Rhine, but that the genotoxic potential has markedly decreased compared with 27 years ago. Furthermore, the Comet assay appears to be a sensitive assay to measure the genotoxic potential of surface waters in fish. 相似文献
35.
Arjan D van Zuilen Ingeborgh van der Tweel Peter J Blankestijn Michiel L Bots Marjolijn van Buren Marc AGJ ten Dam Karin AH Kaasjager Peter JG van de Ven Gerald Vervoort Louis-Jean Vleming Gerry Ligtenberg Jack FM Wetzels 《Trials》2006,7(1):1-9
Background
Patients with chronic kidney disease (CKD) are at a greatly increased risk of developing cardiovascular disease. Recently developed guidelines address multiple risk factors and life-style interventions. However, in current practice few patients reach their targets. A multifactorial approach with the aid of nurse practitioners was effective in achieving treatment goals and reducing vascular events in patients with diabetes mellitus and in patients with heart failure. We propose that this also holds for the CKD population.Design
MASTERPLAN is a multicenter randomized controlled clinical trial designed to evaluate whether a multifactorial approach with the aid of nurse-practicioners reduces cardiovascular risk in patients with CKD. Approximately 800 patients with a creatinine clearance (estimated by Cockcroft-Gault) between 20 to 70 ml/min, will be included. To all patients the same set of guidelines will be applied and specific cardioprotective medication will be prescribed. In the intervention group the nurse practitioner will provide lifestyle advice and actively address treatment goals. Follow-up will be five years. Primary endpoint is the composite of myocardial infarction, stroke and cardiovascular mortality. Secondary endpoints are cardiovascular morbidity, overall mortality, decline of renal function, change in markers of vascular damage and change in quality of life. Enrollment has started in April 2004 and the study is on track with 700 patients included on October 15th, 2005. This article describes the design of the MASTERPLAN study. 相似文献36.
Cationic (positively charged) liposomes have been tested in various gene therapy clinical trials for neoplastic and other
diseases. They have demonstrated selectivity for tumour vascular endothelial cells raising hopes for both antiangiogenic and
antivascular therapies. They are also capable of being selectively delivered to the lungs and liver when administered intravenously.
These vesicles are being targeted to the tumour in various parts of the body by using advanced liposomal systems such as ligand-receptor
and antibody-antigen combinations. At present, the transferrin receptor is commonly used for cancer-targeted drug delivery
systems including cationic liposomes. This review looks at the growing utility of these vesicles for delivery of small molecule
anticancer drugs. 相似文献
37.
Adult rat heart cells were isolated by perfusion of the coronary system of the heart with a 0.05% collagenase solution.In one method (A), cells were finally isolated by shaking the heart fragments in a collagenase solution, after which the cells were washed and suspended in a Ca- and Mg-free buffered salt solution. The effect of different DMSO concentrations, 5, 10, 15, 20, 25, and 30% and the effect of the addition and dilution rate of DMSO on the number of trypan blue-excluding, intact, and contracting cells were studied. The highest DMSO concentration which was tolerated by the isolated adult heart cells was 15%. Variation of addition rate and the dilution rate of DMSO had no effect. After freezing at external cooling rates of 1, 5, 10, 30, and 50 °C/min to ?100 °C, and then rapidly to ?196 °C, in the presence of 5, 10, or 15% DMSO, reanimation of these cells was not achieved.In another method (B), heart fragments, after collagenase perfusion of the heart, were first treated with 5, 10, or 15% DMSO, after which the cells were isolated. If these cells were frozen at 1 °C/min with 10% DMSO, 15% of the cells, expressed as a percentage of the control, remained morphologically intact and 38% of the cells were contracting after thawing. Significantly higher survival percentages of 30 and 61%, respectively, were obtained if the heart fragments were left intact during freezing. 相似文献
38.
Kisztelinski D Alink GM Rietjens IM Bielecki S Tramper J Martens DE 《Biotechnology and bioengineering》2006,95(3):370-383
The aim of the present study is to demonstrate the use of controlled bioreactors for toxicological studies. As a model system the effect of linoleic acid on hybridoma cells is studied in two well-controlled continuously operated bioreactors placed in series. In the first reactor the effect on rapid proliferating cells can be studied, while in the second reactor a special steady state is created, which allows studying the effect on apoptotic cells. Experiments are done at 0, 25, and 50 microM linoleic acid. At the end of the experiment with 50 microM linoleic acid, the concentration of linoleic acid is increased stepwise to determine the cytotoxic level. For rapid proliferating cells exposed to 25 and 50 microM stimulation of growth was observed. At 50 microM there was at the same time an increase in cell death through apoptosis. For stressed apoptotic cells linoleic acid caused partial growth inhibition at 25 and 50 microM and arrest of cell proliferation in the G(2)/M phase at 50 microM. For both, rapid proliferating cells and stressed apoptotic cells, complete growth inhibition occurred at 85 microM, with cells being arrested in the G(2)/M phase and dying mainly through necrosis. Cells in the bioreactor system appeared to be more sensitive towards linoleic acid than cells grown in multi-well plates. (IC(50) = 300 microM; IC(100) = 400 microM). Altogether the results of the present study reveal that the biostat experiments allow detailed analysis of the effect of a bioactive ingredient on cell physiology and behavior. 相似文献
39.
van Beelen VA Aarts JM Reus A Mooibroek H Sijtsma L Bosch D Rietjens IM Alink GM 《FEBS letters》2006,580(19):4587-4590
In this study the n-3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid and docosahexaenoic acid appear to be effective inducers of electrophile-responsive element (EpRE) regulated genes, whereas the n-6 PUFA arachidonic acid is not. These n-3 PUFAs need to be oxidized to induce EpRE-regulated gene expression, as the antioxidant vitamin E can partially inhibit the PUFA induced dose-dependent effect. Results were obtained using a reporter gene assay, real-time RT-PCR and enzyme activity assays. The induction of EpRE-regulated phase II genes by n-3 PUFAs may be a major pathway by which n-3 PUFAs, in contrast to n-6 PUFAs, are chemopreventive and anticarcinogenic. 相似文献
40.
Ashraf M Anwar Youssef FM Nosir Siti Khairani Zainal-Abidin Aref Ajam Hassan Chamsi-Pasha 《Cardiovascular ultrasound》2012,10(1):1-13