全文获取类型
收费全文 | 508篇 |
免费 | 61篇 |
出版年
2021年 | 4篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 17篇 |
2014年 | 21篇 |
2013年 | 9篇 |
2012年 | 30篇 |
2011年 | 27篇 |
2010年 | 17篇 |
2009年 | 14篇 |
2008年 | 19篇 |
2007年 | 22篇 |
2006年 | 22篇 |
2005年 | 17篇 |
2004年 | 33篇 |
2003年 | 25篇 |
2002年 | 18篇 |
2001年 | 17篇 |
2000年 | 14篇 |
1999年 | 7篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 6篇 |
1994年 | 11篇 |
1992年 | 9篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 10篇 |
1988年 | 13篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 11篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1978年 | 5篇 |
1977年 | 11篇 |
1976年 | 5篇 |
1974年 | 6篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1969年 | 4篇 |
1968年 | 3篇 |
1967年 | 4篇 |
1966年 | 3篇 |
排序方式: 共有569条查询结果,搜索用时 46 毫秒
1.
Photoinhibition and Its Recovery in Two Strains of the Cyanobacterium Spirulina platensis 总被引:1,自引:0,他引:1
Vonshak Avigad; Guy Rachel; Poplawsky Ricardo; Ohad Itzhak 《Plant & cell physiology》1988,29(4):721-726
Two strains of Spirulina platensis, marked Sp-G and Sp-RB, werestudied for their response to high photon flux densities (PFD).Sp-RB, a gas vacuolated strain, appeared more sensitive to thehigh PFD treatment as compared with Sp-G, a non-vacuolated strain.The loss of the photosynthetic activity due to the photoinhibitorytreatment was obtained at the level of whole cells as well asthe membrane level. Sp-RB was more sensitive than Sp-G at bothlevels. Experiments using chloramphenicol during the photoinhibitionprocess, and others in which the fate of radio-active labeledthylakoid proteins was followed, indicated that the differencebetween the strains lies in the rate of loss of the Dl polypeptidewith an electrophoretic mobility of 3234 kDa. Both strainsrecovered from the photoinhibition when placed under low PFD.The recovery process started immediately after PFD was reduced,without any observed lag period, and was sensitive to chloramphenicol.Light was required for full recovery of activity. The rate ofrecovery of the two strains studied was very similar.
1Contribution no. 29 of the Micro-Algal Biotechnology Lab. (Received January 11, 1988; Accepted March 31, 1988) 相似文献
2.
Nataly Mancette Rijensky Netta R. Blondheim Shraga Eilon Barnea Nir Peled Eli Rosenbaum Aron Popovtzer Solomon M. Stemmer Alejandro Livoff Mark Shlapobersky Neta Moskovits Dafna Perry Eitan Rubin Itzhak Haviv Arie Admon 《Molecular & cellular proteomics : MCP》2020,19(8):1360-1374
Highlights
- •Sufficient tumor tissues are often unavailable large HLA peptidome discovery.
- •Using patient derived xenograft (PDX) tumors can overcome this limitation.
- •The large PDX HLA peptidomes expand significantly those of the original biopsies.
- •The HLA peptidomes of the PDX tumors included many tumor antigens.
3.
Summary Aluminum extraction from two aluminum-rich fly-ashes by commercial and microbiologically-produced citric acids was tested. Up to 12% Al2O3 of the total was extracted by a 21 hrs1 shaking treatment at 60° C. Extraction efficiency is considerably affected by extracting acid concentration and extraction temperature. The extraction efficiency of microbiologically-produced citric acids was only slightly lower than that of commercial citric acid of equal molarity. 相似文献
4.
Dalia Somjen Itzhak Binderman Esther Berger Arie Harell 《Biochimica et Biophysica Acta (BBA)/General Subjects》1980,627(1):91-100
In vitro cultured bone cells were found to be responsive to hormones and physical forces. A simple device has been developed which enables the direct application of physical forces to tissue culture dishes to which cells are firmly attached. The physical forces created a deformation of the dish. It was found that prostaglandin E2 synthesis underwent a rapid increase, reaching a maximum after 20 min and then declined. Concurrent with the increase in prostaglandin E2 was an increase in cyclic AMP production, having a maximum around 15 min. The increase in cyclic AMP was blocked by indomethacin, the prostaglandin E2 synthesis inhibitor, indicating the dependence of cyclic AMP production on the de novo synthesis of prostaglandin E2. Prostaglandin E2 added to cells mimicked the effect of physical forces on the production of cyclic AMP. The increase in cyclic AMP resulted from an early rise in adenyl cyclase activity (within 5 min) and a later (10 min) increase in phosphodiesterase activity. The same physical forces also stimulatedthe incorporation of thymidine into DNA after 24 h. On addition of prostaglandin E2 the increase in DNA synthesis was also mimicked. Pretreatment of the cells with indomethacin abolished the effect of physical forces on DNA synthesis.The results suggest a stimulus receptor mechanism for physical forces which, like hormonal effectors, are mediated by prostaglandins and stimulate cyclic AMP and DNA synthesis.We believe that physical forces stimulate bone remodelling through such a stimulus receptor system, mediated by prostaglandins. 相似文献
5.
We demonstrate that human electrophysiological recordings of the local field potential (LFP) from intracranial electrodes, acquired from a variety of cerebral regions, show a ubiquitous 1/f2 scaling within the power spectrum. We develop a quantitative model that treats the generation of these fields in an analogous way to that of electronic shot noise, and use this model to specifically address the cause of this 1/f2 Brownian noise. The model gives way to two analytically tractable solutions, both displaying Brownian noise: 1) uncorrelated cells that display sharp initial activity, whose extracellular fields slowly decay in time and 2) rapidly firing, temporally correlated cells that generate UP-DOWN states. 相似文献
6.
7.
Yael Klin Alexander Zlotnik Matthew Boyko Yoram Shapira 《Biochemical and biophysical research communications》2010,399(4):694-698
Excess l-glutamate (glutamate) levels in brain interstitial and cerebrospinal fluids (ISF and CSF, respectively) are the hallmark of several neurodegenerative conditions such as stroke, traumatic brain injury or amyotrophic lateral sclerosis. Its removal could prevent the glutamate excitotoxicity that causes long-lasting neurological deficits. As in previous studies, we have established the role of blood glutamate levels in brain neuroprotection, we have now investigated the contribution of the peripheral organs to the homeostasis of glutamate in blood. We have administered naive rats with intravenous injections of either l-[1-14C] Glutamic acid (l-[1-14C] Glu), l-[G-3H] Glutamic acid (l-[G-3H] Glu) or d-[2,3-3H] Aspartic acid (d-[2,3-3H] Asp), a non-metabolized analog of glutamate, and have followed their distribution into peripheral organs. We have observed that the decay of the radioactivity associated with l-[1-14C] Glu and l-[G-3H] Glu was faster than that associated with glutamate non-metabolized analog, d-[2,3-3H] Asp. l-[1-14C] Glu was subjected in blood to a rapid decarboxylation with the loss of 14CO2. The three major sequestrating organs, serving as depots for the eliminated glutamate and/or its metabolites were skeletal muscle, liver and gut, contributing together 92% or 87% of total l-[U-14C] Glu or d-[2,3-3H] Asp radioactivity capture. l-[U-14C] Glu and d-[2,3-3H] Asp showed a different organ sequestration pattern. We conclude that glutamate is rapidly eliminated from the blood into peripheral tissues, mainly in non-metabolized form. The liver plays a central role in glutamate metabolism and serves as an origin for glutamate metabolites that redistribute into skeletal muscle and gut. The findings of this study suggest now that pharmacological manipulations that reduce the liver glutamate release rate or cause a boosting of the skeletal muscle glutamate pumping rate are likely to cause brain neuroprotection. 相似文献
8.
9.
Background and Aim
Proliferative vitreoretinopathy (PVR) is an active process that develops as a complication upon retinal detachment (RD), accompanied by formation of fibrotic tissue. The main cells involved in the development of fibrotic tissue during PVR are the retinal pigment epithelial (RPE) cells. The RPE cells undergo epithelial-mesenchymal transition (EMT) which leads to complex retinal detachment and loss of vision. Transforming growth factor-β1 (TGF-β1) is considered as the main player in the EMT of RPE cells, even though the mechanism is not fully understood. This study was performed to determine the possible involvement of transforming growth factor β activated kinase 1 (TAK1) in the EMT process of the RPE cells.Methodology
ARPE-19 Cells were treated with 5Z-7 oxozeaenol (TAK1 inhibitor) or SB431542 (TGF-β1 receptor kinase inhibitor) followed by TGF-β1 stimulation. Immunofluorescence, scratch assay Real time PCR and collagen contraction assay assessed the EMT features. The phosphorylation of Smad2/3 and p38 was examined using western blots analysis.Results
This study demonstrates that stimulation of RPE cells with TGF-β1 increases α-SMA expression, cell migration and cell contractility, all of which are EMT features. Remarkably, addition of TAK1 inhibitor abolishes all these processes. Furthermore, we show hereby that TAK1 regulates not only the activation of the non-canonical cascade of TGF-β1 (p38), but also the canonical cascade, the Smad2/3 activation. Thus, the outcome of the TGF-β response in RPE cells is TAK1 dependent.Conclusions/Significance
This work demonstrated TAK1, a component of the non-canonical pathway of TGF-β1, is a key player in the EMT process, thus provides deep insight into the pathogenesis of PVR. The ability to halt the process of EMT in RPE cells may reduce the severity of the fibrotic response that occurs upon PVR, leading to a better prognosis and increase the probability of success in RD treatment. 相似文献10.
Shiran Shapira Oded Ben-Amotz Osnat Sher Dina Kazanov Jacob Mashiah Sarah Kraus Eyal Gur Nadir Arber 《PloS one》2015,10(10)