全文获取类型
收费全文 | 1912篇 |
免费 | 10篇 |
国内免费 | 3篇 |
出版年
2023年 | 3篇 |
2022年 | 9篇 |
2020年 | 2篇 |
2019年 | 46篇 |
2018年 | 59篇 |
2017年 | 11篇 |
2016年 | 8篇 |
2015年 | 11篇 |
2014年 | 171篇 |
2013年 | 130篇 |
2012年 | 117篇 |
2011年 | 190篇 |
2010年 | 147篇 |
2009年 | 151篇 |
2008年 | 157篇 |
2007年 | 128篇 |
2006年 | 82篇 |
2005年 | 84篇 |
2004年 | 22篇 |
2003年 | 10篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 9篇 |
1998年 | 6篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1985年 | 18篇 |
1984年 | 53篇 |
1983年 | 39篇 |
1982年 | 47篇 |
1981年 | 30篇 |
1980年 | 27篇 |
1979年 | 32篇 |
1978年 | 25篇 |
1977年 | 20篇 |
1976年 | 12篇 |
1975年 | 11篇 |
1974年 | 16篇 |
1973年 | 7篇 |
1972年 | 2篇 |
排序方式: 共有1925条查询结果,搜索用时 500 毫秒
91.
92.
93.
94.
When the eicosapentaenoic acid (EPA)-deficient mutant strain IK-1Delta8 of the marine EPA-producing Shewanella marinintestina IK-1 was treated with various concentrations of hydrogen peroxide (H(2)O(2)), its colony-forming ability decreased more than that of the wild type. Protein carbonylation, induced by treating cells with 0.01 mM H(2)O(2) under bacteriostatic conditions, was enhanced only in cells lacking EPA. The amount of cells recovered from the cultures was decreased more significantly by the presence of H(2)O(2) for cells lacking EPA than for those producing EPA. Treatment of the cells with 0.1 mM H(2)O(2) resulted in much lower intracellular concentrations of H(2)O(2) being consistently detected in cells with EPA than in those without EPA. These results suggest that cellular EPA can directly protect cells against oxidative damage by shielding the entry of exogenously added H(2)O(2) in S. marinintestina IK-1. 相似文献
95.
Limatola C Massa V Lauro C Catalano M Giovanetti A Nuccitelli S Spinedi A 《FEBS letters》2007,581(14):2641-2646
Chemotaxis induction is a major effect evoked by stimulation of the chemokine receptor CXCR4 with its sole ligand CXCL12. We now report that treatment of CHP-100 human neuroepithelioma cells with the glucosylceramide synthase (GCS) inhibitor DL-threo-1-phenyl-2-hexadecanoylamino-3-pyrrolidino-1-propanol inhibits CXCR4-dependent chemotaxis. We provide evidence that the phenomenon is not due to unspecific effects of the inhibitor employed and that inhibition of GCS neither affects total or plasmamembrane CXCR4 expression, nor CXCL12-induced Ca(2+) mobilization. The effects of the GCS inhibitor on impairment of CXCL12-induced cell migration temporally correlated with a pronounced downregulation of neutral glycosphingolipids, particularly glucosylceramide, and with a delayed and more moderate downregulation of gangliosides; moreover, exogenously administered glycosphingolipids allowed resumption of CXCR4-dependent chemotaxis. Altogether our results provide evidence, for the first time, for a role glycosphingolipids in sustaining CXCL12-induced cell migration. 相似文献
96.
97.
Zimei Dong Fangfang Cheng Yibo Yang Fenxi Zhang Guangwen Chen Dezeng Liu 《Experimental cell research》2019,374(1):76-84
FLOTILLIN-1 and FLOTILLIN-2 are membrane rafts associated proteins that have been implicated in insulin and growth factor signaling, endocytosis, cell migration, proliferation, differentiation, cytoskeleton remodeling and membrane trafficking. Furthermore, FLOTILLINs also play important roles in the progression of cancer and neurodegenerative diseases. In this study, the roles of flotillins are investigated in planarian Dugesia japonica. The results show that Djflotillin-1 and Djflotillin-2 play a key role in homeostasis maintenance and regeneration process by regulating the proliferation of the neoblast cells, they are not involved in the maintenance and regeneration of the central nervous system in planarians. 相似文献
98.
!vette Martínez-Vieyra Mario Rodríguez-Varela Diana García-Rubio Beatriz De la Mora-Mojica Juan Méndez-Méndez Carlos Durán-Álvarez Doris Cerecedo 《生物化学与生物物理学报:生物膜》2019,1861(10):182996
Genetic and environmental factors may contribute to high blood pressure, which is termed essential hypertension. Hypertension is a major independent risk factor for cardiovascular disease, stroke and renal failure; thus, elucidation of the etiopathology of hypertension merits further research. We recently reported that the platelets and neutrophils of patients with hypertension exhibit altered biophysical characteristics. In the present study, we assessed whether the major structural elements of erythrocyte plasma membranes are altered in individuals with hypertension. We compared the phospholipid (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, sphingosine) and cholesterol contents of erythrocytes from individuals with hypertension (HTN) and healthy individuals (HI) using LC/MS-MS. HTN erythrocytes contained higher phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine contents and a lower cholesterol content than HI erythrocytes. Furthermore, atomic force microscopy revealed important morphological changes in HTN erythrocytes, which reflected the increased membrane fragility and fluidity and higher levels of oxidative stress observed in HTN erythrocytes using spectrophotofluorometry, flow cytometry and spectrometry. This study reveals that alterations to the lipid contents of erythrocyte plasma membranes occur in hypertension, and these alterations in lipid composition result in morphological and physiological abnormalities that modify the dynamic properties of erythrocytes and contribute to the pathophysiology of hypertension. 相似文献
99.
Egor E. Diakonov Anastasiia V. Selenina Alexey N. Tomilin Anna S. Tsimokha 《Biochemical and biophysical research communications》2019,508(2):368-373
The ubiquitin proteasome system is involved in the regulation of most basic intracellular processes, and deregulation of this system can results in certain kinds of human diseases. Proteolytic core this system, the 20S proteasome, has been found in physiological fluids of both healthy humans and patients suffering from a variety of inflammatory, autoimmune, and neoplastic diseases. The concentration of these extracellular proteasomes has been found to correlate with the diseased state, being of a prognostic significance. The transport mechanisms and functions of these proteasomes, however, are largely unclear. Previous studies revealed that the transport of extracellular proteasomes may occur via microvesicles and exosomes, which led to the hypothesis that extracellular proteasomes are implicated in cell-to-cell communication process. Here we show that microvesicles and exosomes, two major known types of intercellular vehicles, contain no detectable proteasomes. Moreover, neither affinity purified nor naturally released into conditioned medium by donor cells 20S proteasomes could penetrate recipient HeLa cells. Taken together, these results suggest that extracellular proteasomes are unlikely to be involved in the cell-to-cell communication and that their release by cells serve other biological purposes. 相似文献
100.
Sterol structure influences liquid ordered domains in membranes, and the dependence of biological functions on sterol structure can help identify processes dependent on ordered domains. In this study we compared the effect of sterol structure on ordered domain formation in symmetric vesicles composed of mixtures of sphingomyelin, 1, 2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and cholesterol, and in asymmetric vesicles in which sphingomyelin was introduced into the outer leaflet of vesicles composed of DOPC and cholesterol. In most cases, sterol behavior was similar in symmetric and asymmetric vesicles, with ordered domains most strongly stabilized by 7-dehydrocholesterol (7DHC) and cholesterol, stabilized to a moderate degree by lanosterol, epicholesterol and desmosterol, and very little if at all by 4-cholesten-3-one. However, in asymmetric vesicles desmosterol stabilized ordered domain almost as well as cholesterol, and to a much greater degree than epicholesterol, so that the ability to support ordered domains decreased in the order 7-DHC > cholesterol > desmosterol > lanosterol > epicholesterol > 4-cholesten-3-one. This contrasts with values for intermediate stabilizing sterols in symmetric vesicles in which the ranking was cholesterol > lanosterol ~ desmosterol ~ epicholesterol or prior studies in which the ranking was cholesterol ~ epicholesterol > lanosterol ~ desmosterol. The reasons for these differences are discussed. Based on these results, we re-evaluated our prior studies in cells and conclude that endocytosis levels and bacterial uptake are even more closely correlated with the ability of sterols to form ordered domains than previously thought, and do not necessarily require that a sterol have a 3β-OH group. 相似文献