全文获取类型
收费全文 | 495篇 |
免费 | 20篇 |
专业分类
515篇 |
出版年
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 23篇 |
2020年 | 10篇 |
2019年 | 18篇 |
2018年 | 22篇 |
2017年 | 10篇 |
2016年 | 26篇 |
2015年 | 23篇 |
2014年 | 21篇 |
2013年 | 34篇 |
2012年 | 47篇 |
2011年 | 47篇 |
2010年 | 24篇 |
2009年 | 26篇 |
2008年 | 31篇 |
2007年 | 23篇 |
2006年 | 21篇 |
2005年 | 23篇 |
2004年 | 23篇 |
2003年 | 15篇 |
2002年 | 12篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1996年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
排序方式: 共有515条查询结果,搜索用时 0 毫秒
141.
Role of the nitric oxide pathway in ischemia-reperfusion injury in isolated perfused guinea pig lungs 总被引:4,自引:0,他引:4
Altunkaya A Oz E Sivrikoz MC Halit V Yener N Erdoĝan D Ozoĝul C 《Molecular and cellular biochemistry》2006,290(1-2):9-16
We examined the role of the nitric oxide (NO) pathway on ischemia-reperfusion injury via the use of isolated perfused guinea
pig lungs.
We administered both L-Arginine and N-nitro-L-arginine methyl ester (L-NAME) to the lungs in or after 3 h of ischemia.
We observed pulmonary artery pressures as well as tissue and perfusate malondialdehyde (MDA) and glutathione (GSH) levels.
We observed that L-NAME significantly increased both tissue and perfusate GSH levels and pulmonary artery pressures, but it
decreased both tissue and perfusate MDA levels. On the other hand, L-arginine significantly decreased pulmonary artery pressure
and both tissue and perfusate glutathione levels, but it increased both tissue and perfusate MDA levels. Electron microscopic
evaluation supported our findings by indicating the preservation of lamellar bodies of type II pneumocytes.
We concluded that L-NAME administration during reperfusion improves lung recovery from ischemic injury. 相似文献
142.
T. Abdülkadir Coban Şükrü Beydemir İlhami Gücin Deniz Ekinci Alessio Innocenti Daniela Vullo Claudiu T. Supuran 《Bioorganic & medicinal chemistry》2009,17(16):5791-5795
Sildenafil citrate, a phosphodiesterase-5 (PDE5) inhibitor widely used for the treatment of erectile dysfunction was investigated for its interaction with the zinc-enzyme carbonic anhydrase (CA, EC 4.2.1.1), as it has in its molecule a piperazine moiety also found in some CA activators (CAAs). Sildenafil was a potent, low micromolar activator of several CA isozymes, such as CA I, VA and VI (KAs in the range of 1.08–6.54 μM), and activated slightly less the isoforms CA III, IV and VA (KAs of 13.4–16.8 μM). CA isozymes II, IX, XIII and XIV showed activation constants in the range of 27.5–34.0 μM, whereas the least activated isoforms were CA VII and XII (KAs of 72.9–73.0 μM). Sildenafil citrate was also given orally to Sprague-Dawley rats at 1 mg/kg body weight. Red blood cell CA activity was inhibited in the treated animals at 3–5 h post-administration (in the range of 60–85%), probably due to NO/nitrite formed by PDE5 inhibition or by another, unknown mechanism. Whether CA activation by sildenafil has clinical consequences in humans is beyond the scope of the present work and warrants further studies. 相似文献
143.
The ever-evolving understanding of the neuronal systems involved in Parkinson's disease together with the recent advances in recombinant viral vector technology has led to the development of several gene therapy applications that are now entering into clinical testing phase. To date, four fundamentally different approaches have been pursued utilizing recombinant adeno-associated virus and lentiviruses as vectors for delivery. These strategies aim either to restore the lost brain functions by substitution of enzymes critical for synthesis of neurotransmitters or neurotrophic factors as a means to boost the function of remaining neurons in the diseased brain. In this review we discuss the differences in mechanism of action and describe the scientific rationale behind the currently tested gene therapy approaches for Parkinson's disease in some detail and pinpoint their individual unique strengths and weaknesses. 相似文献
144.
Veyis Karakoc Erkut Yılmaz Deniz Türkmen Nevra Öztürk Sinan Akgöl Adil Denizli 《International journal of biological macromolecules》2009,45(2):188-193
Poly(hydroxyethyl methacrylate) (PHEMA) nanoparticles with an average size of 300 nm in diameter and with a polydispersity index of 1.156 were produced by surfactant free emulsion polymerization. Specific surface area of the PHEMA nanoparticles was found to be 996 m2/g. Metal-chelating ligand 3-(2-imidazoline-1-yl)propyl(triethoxysilane) (IMEO) was covalently attached to the PHEMA nanoparticles. IMEO content was 0.97 mmol IEMO/g. The morphology and properties of these nanoparticles were characterized with scanning electron microscopy, Fourier transform infrared spectroscopy and atomic force microscopy. The Cu2+-chelated PHEMA–IMEO nanoparticles were used in the adsorption-elution studies of human serum albumin (HSA) in a batch system. Maximum HSA adsorption amount of the Cu2+ chelated nanoparticles was 680 mg HSA/g. The PHEMA–IMEO–Cu2+ nanoparticles exhibited a quite high adsorption capacity and fast adsorption rate due to their high specific surface area and the absence of internal diffusion resistance. 相似文献
145.
Enhanced Fusion Pore Expansion Mediated by the Trans-Acting Endodomain of the Reovirus FAST Proteins
The reovirus fusion-associated small transmembrane (FAST) proteins are virus-encoded membrane fusion proteins that function as dedicated cell–cell fusogens. The topology of these small, single-pass membrane proteins orients the majority of the protein on the distal side of the membrane (i.e., inside the cell). We now show that ectopic expression of the endodomains of the p10, p14, and p15 FAST proteins enhances syncytiogenesis induced by the full-length FAST proteins, both homotypically and heterotypically. Results further indicate that the 68-residue cytoplasmic endodomain of the p14 FAST protein (1) is endogenously generated from full-length p14 protein expressed in virus-infected or transfected cells; (2) enhances syncytiogenesis subsequent to stable pore formation; (3) increases the syncytiogenic activity of heterologous fusion proteins, including the differentiation-dependent fusion of murine myoblasts; (4) exerts its enhancing activity from the cytosol, independent of direct interactions with either the fusogen or the membranes being fused; and (5) contains several regions with protein–protein interaction motifs that influence enhancing activity. We propose that the unique evolution of the FAST proteins as virus-encoded cellular fusogens has allowed them to generate a trans-acting, soluble endodomain peptide to harness a cellular pathway or process involved in the poorly understood process that facilitates the transition from microfusion pores to macrofusion and syncytiogenesis. 相似文献
146.
147.
Injury of the nervous system, particularly in the spinal cord, impairs the quality of life of the patient by resulting in permanent loss of neurologic function. The main limitation in spinal cord regeneration is the lack of extracellular matrix to guide nerves for functional recovery of the transected nerve tissue. In the present study, a tissue engineered nerve tube was prepared by wrapping neural stem cells (NSCs) on aligned fibers using a micropatterned film with astrocytes aligned along the microgrooves to support the NSCs. Initially the cell behavior on micropatterns and parallel fibers was investigated with cytoskeletal and nuclear staining, immunocytochemistry, and proliferation assay using the fiber and the film system separately. The results showed that both cells, NSCs in undifferentiated and astrocytes in differentiated form, were oriented in the direction of the guiding and support elements, the microgrooves, and the microfibers. They were able to grow and increase in number on these cell carriers. This trend was also maintained after the components were brought together in a nerve tube form and testing in coculture. The cells were able to survive and maintained their orientation in the 3D tissue engineered construct. The guided nerve tissue engineering approach tested in the present study with parallel NSCs and support cells in the tubular construct is expected to provide an appropriate environment for nerve regeneration in vivo. 相似文献
148.
Erezyilmaz DF 《Integrative and comparative biology》2006,46(6):795-807
The problem of insect metamorphosis has inspired naturalistsfor centuries. One question that often arises is why some insects,such as butterflies and bees, undergo a fairly radical metamorphosiswhile others, such as crickets and lice, do not. Even beforethe concept of homology emerged scientists speculated whichstage found in more direct-developing insects would correspondwith the pupal stage of metamorphosing insects. William Harvey(1651) considered the pupal stage to be a continuation of embryonicevents, calling it a "second egg." Since then variations ofthis idea have emerged over the centuries of scientific researchand have been supported by a wide variety of methods and rationales.This review will follow those ideas and the ideas that emergedin opposition to them to the present state of the field. 相似文献
149.
Deniz enol Cihat Uar eyma Toy Ayegül Ksaolu Davut
zba Yüksel Ersoy Sedat Yldz 《Journal of musculoskeletal & neuronal interactions》2021,21(1):85
Objectives:Menstrual cycle (MC) can affect not only the female reproductive system, but also functions such as neuromuscular performance. For this reason, the aim of this study is to investigate the effect of hypothalamic-pituitary-adrenal axis (HPA) activity in MC on proprioception, balance and reaction times.Methods:For cortisol analysis, saliva samples were taken from the same women (n=43) in the four phases of MC. While State Trait Anxiety Inventory-I (STAI-I) was applied in each phase to support cortisol analysis, pain was measured with visual analogue scale (VAS). Proprioception, dynamic balance, visual and auditory reaction times (VRT-ART) measurements were made in the four phases of MC.Results:Cortisol, STAI-I and VAS scores, angular deviations in proprioception measurements, dynamic balance scores, VRT and ART measurements were found to show statistically significant difference between MC phases (p<0.05). As a result of the post hoc test conducted to find out which MC phase the statistical difference resulted from, it was found that statistically significant difference was caused by the mensturation (M) phase (p<0.05).Conclusions:It was found that neuromuscular performance and postural control was negatively affected by HPA axis activity in M phase of MC and by pain, which is a significant menstrual symptom. 相似文献
150.