全文获取类型
收费全文 | 307篇 |
免费 | 16篇 |
国内免费 | 9篇 |
学科分类
医药卫生 | 332篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 5篇 |
2015年 | 15篇 |
2014年 | 17篇 |
2013年 | 19篇 |
2012年 | 19篇 |
2011年 | 15篇 |
2010年 | 12篇 |
2009年 | 21篇 |
2008年 | 22篇 |
2007年 | 13篇 |
2006年 | 8篇 |
2005年 | 8篇 |
2004年 | 13篇 |
2003年 | 16篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 11篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有332条查询结果,搜索用时 0 毫秒
1.
Long-term adhesion and survival of dissociated cortical neurons on miniaturised chemical patterns 总被引:1,自引:0,他引:1
The influence of neuron-adhesive pattern geometry on long-term adhesion, survival and pattern compliance of cortical neuronal
tissue was studied over a period of 15 days. The results are relevant for a successful, long-term integration of neuronal
cells with electrodes from micro-electronic devices. Microwells (depth 0.5μm), with diameters of 25, 50, 100 and 150 μm and
spacing distances of 15, 30, 60 and 90 μm, were etched in a neuron-repellent fluorocarbon (FC) layer and coated with neuron-adhesive
polyethylenimine (PEI). Results showed that adhesion, survival and compliance to the underlying patterns were geometry-and
time-dependent. After 1 day, adhesion was inversely proportional to the diameter of the microwells, thus favouring the 25
μm microwells. However, adhesion was best on 50 μm microwells after 15 days. Survival of neurons was limited on 25 μm microwells
(viability function V(D, T) was 0.08), as opposed to the better survival on 150 μm microwells (V(D, T) was 0.25) after 15
days. In summary, the study shows that the chemical patterns with microwells of 150 μm diameter (90 μm spacing gap) are most
suitable for application on neuro-electronic devices owing to the better long-term survival and high pattern compliance of
the neuronal cells. 相似文献
2.
Mitsuo Shimada Katsuhiko Yanaga Keiji Kishikawa Saburo Kakizoe Hidetoshi Itasaka Tetsuo Ikeda Taketoshi Suehiro Keizo Sugimachi 《Transplant international》1993,6(1):4-7
Rapid and reliable assessment of hepatic graft viability is important for successful orthotopic liver transplantation (OLTx). OLTx was performed in 11 pairs of pigs via a venovenous bypass. Six of these grafts were transplanted immediately (group A), while the other five were preserved in University of Wisconsin (UW) solution for 24 h and then transplanted (group B). All grafts were flushed with 300 ml of chilled (4°C) Ringer's lactate solution before reperfusion of the graft, when 20 ml of effluent from the graft was collected and the concentrations of ammonia, lactic acid, GOT, and LDH were measured. Four of the six pigs in group A survived longer than 3 days, while the other two pigs died of causes other than graft dysfunction. All five pigs in group B died either of hemoperitoneum or hemodynamic instability due to liver failure. The histology of postperfusion biopsies in group A showed minimal pathological changes, while the grafts in group B revealed moderate to severe ischemic injuries. Ammonia and lactic acid in the effluent of group B were significantly higher than those of group A (1511±216 vs 417±333 g/dl and 114.1±12.2 vs 91.4±12.2 mg/dl, respectively; P<0.05 in both cases). Before reperfusion, the rate of total adenine nucleotides in all of the substances in the graft, which were measured using high performance liquid chromatography (HPLC), inversely correlated with the ammonia levels in the effluent. We conclude that an analysis of the effluent, (i.e. the levels of ammonia and lactic acid), flushed from a hepatic graft before reperfusion could serve as a predictor of hepatic graft viability. 相似文献
3.
Thierry Humbert Cuong Luu-Duc Michel Comet Pierre Demenge 《European journal of nuclear medicine and molecular imaging》1991,18(11):870-878
Previous studies led us to hypothesize that a fatty acid analogue, 15-p-iodophenyl--methyl pentadecanoic acid (IMPPA or BMIPP), which is taken up but not quickly metabolized by heart cells, would be a more suitable tracer of cellular viability than thallium-201. Biodistribution studies of 1-14C-IMPPA in conscious, freely moving rats showed that the concentration ratio of radioactivity in the heart with respect to the blood was about 8 for at least 60 min after intravenous administration, permitting its use as a putative tracer in these conscious, freely moving rats. Thereafter, the myocardial uptake of14C-IMPPA was studied in isoproterenol-treated rats (daily treatment for 10 days in order to induce cardiac hypertrophy and necrotic foci) with respect to control ones. Comparison of myocardial localizations by quantitative autoradiography of the uptake of201Tl and14C-IMPPA with that of triphenyltetrazolium chloride (TTC) staining enabled comparative evaluation of nutritional blood flow, localization and uptake of14C-IMPPA and necrotic foci size. Distributions of14C-IMPPA and2011 T1 in control rats' hearts were homogeneous, like TTC staining. In infarcted hearts, areas of decreased14C-IMPPA uptake were nearly the same (100%±5%) as those unstained by TTC. These areas were larger than those showing a decrease in thallium uptake (about 70%±5% of the total scar size). Therefore, IMPPA seems to be a more accurate and sensitive indicator of necrosis localization compared with thallium. It may be a useful agent for assessment of myocardial viability by single photon emission tomography (SPET) imaging. 相似文献
4.
《Toxicology mechanisms and methods》2013,23(8):482-486
This study compared the two different commercially available in vitro viability assays: XTT and Alamar blue (AB), to detect anti-proliferative effects of AT-101, a cotton plant extract, on six different human carcinoma cell lines including: prostate (PC-3 and DU-145), breast (MCF-7 and MDA-MB-231), and ovary (OVCAR-3 and MDAH 2774) in a time- and dose-dependent manner. Cells were exposed to AT-101 in the concentration range of 2.5–40 µM for 24, 48, and 72?h. The AB assay was slightly more sensitive than the XTT assay in the evaluation of AT-101 at 24?h, suggesting that the AB assay might be used for detecting early changes in cell viability as compared to the XTT assay. Moreover, the AB assay showed less intra-assay variability as compared to the XTT. The non-toxic, non-radioactive AB metabolism assay allows rapid assessment of large numbers of samples, with simple equipment and at reduced cost for continuous monitoring of cancer cell viability, and, thus, should be accepted as a suitable alternative viability method. 相似文献
5.
We investigated the effects of β-glucan purified from Paenibacillus polymyxa JB115 on the viability and proliferation of splenocytes. Splenocytes play a critical role in host immunity. MTT assays and trypan blue exclusion tests revealed that β-glucan significantly promoted the viability and proliferation of splenocytes over a range of concentrations. However, there was no specific subset change. β-glucan protected splenocytes from cytokine withdrawal-induced spontaneous cell death. For further mechanistic studies, ELISA assay revealed that β-glucan enhanced the expression of anti-apoptotic molecules and interleukin 7 (IL-7), a cytokine critical for lymphocyte survival. We also investigated the IL-2 dependency of β-glucan-treated splenocytes to determine if treated cells could still undergo clonal expansion. In flow cytometric analysis, β-glucan induced increased levels of the activation marker CD25 on the surface of splenocytes and β-glucan-treated splenocytes showed higher proliferation rates in response to IL-2 treatment. This study demonstrates that β-glucan can enhance the survival of splenocytes and provides valuable information to broaden the use of β-glucan in research fields. 相似文献
6.
Thaís Batista de Carvalho Teresa Cristina Goulart Oliveira-Sequeira Semíramis Guimar?es 《Revista do Instituto de Medicina Tropical de S?o Paulo》2014,56(1):43-47
The quest for new antiparasitic alternatives has led researchers to base
their studies on insights into biology, host-parasite interactions and pathogenesis.
In this context, proteases and their inhibitors are focused, respectively, as
druggable targets and new therapy alternatives. Herein, we proposed to evaluate the
in vitro effect of the cysteine protease inhibitor E-64 on
Giardia trophozoites growth, adherence and viability.
Trophozoites (105) were exposed to E-64 at different final concentrations,
for 24, 48 and 72 h at 37 °C. In the growth and adherence assays, the number of
trophozoites was estimated microscopically in a haemocytometer, whereas cell
viability was evaluated by a dye-reduction assay using MTT. The E-64 inhibitor showed
effect on growth, adherence and viability of trophozoites, however, its better
performance was detected in the 100 µM-treated cultures. Although metronidazole was
more effective, the E-64 was shown to be able to inhibit growth, adherence and
viability rates by ≥ 50%. These results reveal that E-64 can interfere in some
crucial processes to the parasite survival and they open perspectives for future
investigations in order to confirm the real antigiardial potential of the protease
inhibitors. 相似文献
7.
Summary Studies of homograft valves in the past two decades have suggested that viable valves, i.e., those maintaining chemical and structural integrity of their leaflet intercellular matrix, have a better long-term function than nonviable valves. The most effective qualitative methods of assessing leaflet viability involve destruction of the valve leaflets; thus, these methods have been limited to random use in selected valves. A study was conducted in swine in an attempt to establish a control tissue which could be tested in place of the homograft leaflets, thereby determining viability levels of every valve clinically implanted and correlating the results with long-term clinical function. Thirty samples each of the aortic and pulmonary artery wall and tricuspid leaflet were compared with aortic and pulmonary leaflets. Utilizing the technique of C14-proline uptake, viability was assessed at procurement, following sterilization, and following cryopreservation and short-term storage. The tricuspid leaflet was found to retain the same level of viability as the aortic and pulmonary leaflets before and after the cryopreservation period. It was concluded that the tricuspid leaflet could be utilized as the control tissue. 相似文献
8.
《Dental materials》2020,36(2):270-283
ObjectiveTo determine the cytotoxic and genotoxic potential of the respirable fraction of composite dust (<4 μm) on human bronchial epithelial cells.MethodsComposite sticks of three commercial dental composites (Filtek Supreme XTE, Grandio, Transbond XT) were ground in an enclosed plexiglass chamber with a rough dental bur (grain-size 100 μm) and the generated airborne respirable dust was collected in a personal cyclone on a teflon filter (pore size 5 μm). Immediately after particle collection, the dust was quantified gravimetrically and the particles were suspended in cell culturing medium. Next, human bronchial epithelial cells (16HBE14o-) were exposed to the suspensions (3 μg/ml–400 μg/ml). After 24 h, cell viability (WST-1 assay) and membrane integrity (LDH assay) were evaluated. Furthermore, the genotoxic effect of a sub-cytotoxic concentration (50 μg/ml) of composite dust was evaluated by the comet assay after 3 h exposure and cell cycle disturbances were analyzed by flow cytometry. Cellular uptake of particles was evaluated by transmission electronic microscope (TEM).ResultsFor all three tested composite materials, a decrease in metabolic activity of 10–35% was observed when the cells were exposed to the highest concentrations (100 μg/ml–400 μg/ml). Toxicity was partially linked to membrane disruption especially after 72 h exposure. All tested composites provoked a mild genotoxic effect after short-term exposure compared to the control groups. TEM revealed that respirable particles of all tested composites were taken up by the cells.SignificanceThe respirable fraction of composite dust only showed cytotoxic effects at the highest concentrations, whereas mild genotoxicity was observed after exposure to a sub-cytotoxic concentration. 相似文献
9.
软骨移植物主要包括自体软骨、同种异体软骨、冷冻同种胚胎软骨、骨膜、软骨膜和生物材料等。但软骨移植存在许多缺陷,如供区继发性病变、进行性供区结构异常、移植物弯曲变形,移植物吸收与存活等问题。本文就提高自体软骨移植物活性的方法,包括软骨碎片或颗粒移植和包裹技术等进行综述。 相似文献
10.
Anne Kaltoft Morten Bøttcher Niels Peter Rønnow Sand Christian Flø Torsten Toftegaard Nielsen Michael Rehling 《Scandinavian cardiovascular journal : SCJ》2013,47(4):245-251
Objective - Assessment of myocardial viability by 99m Tc-Sestamibi Single Photon Emission Computerized Tomography (SPECT) has been suggested as a more readily available and cheaper alternative to Positron Emission Tomography (PET) with 13 N-ammonia (NH 3 ) and 18 F-fluoro-deoxy-glucose (FDG). We hypothesized that a semi-quantitative evaluation by SPECT could delineate myocardial viability with an acceptable concordance to PET. Design - Fifty patients (age 57 - 7 years; ejection fraction 28 - 8%), with ischemic cardiomyopathy, underwent SPECT and PET imaging in random order. Viability by SPECT was defined as a defect size <50% of the segment area, or a defect representing S 50% of the segment but with a mean activity S 50% of peak activity. PET viability was defined as a perfusion score >2 and FDG score h 2 (five-point scale, 0 = normal, 4 = absent activity). Results - By segmental comparison to PET, SPECT yielded a sensitivity and specificity of 87% and 82% for detection of viable myocardium. The positive and negative predictive values were 96% and 58%, respectively. Conclusion - In patients with severe ischemic cardiomyopathy 99m Tc-Sestamibi SPECT can delineate viable myocardium with an acceptable segmental concordance to NH 3 /FDG PET. 相似文献