全文获取类型
收费全文 | 293篇 |
免费 | 26篇 |
出版年
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 12篇 |
2014年 | 13篇 |
2013年 | 18篇 |
2012年 | 22篇 |
2011年 | 14篇 |
2010年 | 13篇 |
2009年 | 11篇 |
2008年 | 8篇 |
2007年 | 10篇 |
2006年 | 12篇 |
2005年 | 9篇 |
2004年 | 20篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 6篇 |
2000年 | 12篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有319条查询结果,搜索用时 15 毫秒
311.
Changes in ethanol, lactate and malate content in Acer pseudoplatanus cells: effects of fusicoccin and O2 availability 总被引:1,自引:0,他引:1
Changes in the contents of ethanol, lactate and malate were determined at different activities of the plasma membrane H+ pump [in the presence and absence of fusicoccin (FC)] and at different O2 availability in cultured cells of Acer pseudoplatanus L. FC induced acidification of the medium under all tested conditions of O2 availability. At low O2 concentrations both ethanolic and lactic fermentations occurred, and FC markedly stimulated lactate production but had no effect on ethanol production. There was also a small, stimulating effect of FC on malate production. At high O2 concentrations no ethanol production was observed and lactate production was reduced. Under these conditions the stimulating effect of FC on lactate production decreased, while that on malate production increased. FC-induced synthesis of lactate and malate is interpreted as depending on the activation of lactate dehydrogenase (EC 1.1.1.27) and phosphoenolpyruvate carboxylase (EC 4.1.1.31) (alkaline pH optima), respectively, due to the alkalinization of the cytoplasmic pH resulting from the stimulation of the H+ pump by FC. These results suggest that the balance between the two pH stat systems depends on the availability of O2 . 相似文献
312.
313.
Two non mitochondrial systems involved in ATP-dependent Ca2+ accumulation have been described and characterized in two membrane fractions from pea internodes purified on a metrizamide-sucrose discontinuous gradient. In the lighter membrane fraction an ATP-dependent Ca2+ accumulation system, which shows the characteristics of an ATP-dependent H+/Ca2+ antiport, predominates. This system is inhibited by FCCP and nigericin and stimulated by 50 mM KCl. It is saturated by 0.8–1.0 mM MgSO4-ATP, strictly requires ATP and is severely inhibited by an excess of free Mg2+ or Mn2+. A second system of ATP-dependent Ca2+ accumulation, recovered mainly in the heavier membrane fraction, is insensitive to FCCP, is saturated by 8–10 mM MgSO4-ATP, can utilize also ITP or other nucleoside triphosphates although at lower rate than ATP and is only scarcely affected by an excess of free Mg2+ or Mn2+. This system is interpreted as corresponding to the (Ca2+ + Mg2+)-ATPase described by Dieter, P. and Marmé, D. ((1980) Planta 150, 1–8). 相似文献
314.
Tody C. Rodman Fred H. Pruslin Nicholas Chiorazzi Mary Ann Michelis Ronald Winston 《Molecular reproduction and development》1983,8(2):129-147
A basic protein of apparent molecular weight 15,000 d (p15) has been identified as a tissue-specific species-unique component of spermatogenic cells of human semen. Cytoimmunochemical study with a monoclonal antibody indicates that p15 resides in a perinuclear space in morphologically normal spermatozoa and differs in distribution and stat in abnormal seminal cell and nonnucleated bodeis. Biochemical analysis indicateds that p15 occurs as four variiants, differentially migratory on acetic acid/urea gel and differnetially extractable by NaCl in reducing solution. By correlation of the cytologic and biochemical data, we propose that variant 1 is the unmodified form of p15; in the normal progression of spermiogenesis p15 is modified to variants 2 and 3 and in the absence of the normal progression is unmodified or aberrantly modified to variant 4. The association of molecular abnormality in p15 with morphologically abnormal sperm suggests that p15 may play a role in sperm-head shaping. 相似文献
315.
Ivana Cacciatore Antonio Di Stefano Grazia Luisi Francesco Pinnen Piera Sozio 《Journal of peptide science》2004,10(2):109-114
The fully deprotected glutathione analogue containing the aminomethylene unit as transition state isostere of the gamma-Glu-Cys peptide bond was synthesized for the first time and characterized in both the reduced and oxidized forms. 相似文献
316.
Increased plasma volume in two models of portal hypertension in the rat: cirrhosis of the liver and partial portal vein ligation 总被引:1,自引:0,他引:1
D Kravetz M T Arderiu J Bosch C Piera J Setoain J Rodés 《Revista Espanola de Fisiología》1987,43(2):179-183
Portal hypertension has been studied in the rat to see if it is associated to altered blood volume composition, as it has been shown in other species. Plasma volume was measured by isotope dilution using 99mTc labelled albumin in three groups of male Sprague-Dawley rats: normal rats (controls), partially ligated portal vein rats and rats with Cl4C induced cirrhosis. Plasma volume was significantly higher in rats with portal hypertension due to partially ligated portal vein and cirrhosis than in control animals. Similarly, the calculated blood volume was also significantly higher in the portal hypertensive animals than in control group. Portal hypertension in the rat, therefore, has been demonstrated to be associated to a marked hypervolemia and this finding should be taken into consideration in haemodynamic and pharmacokinetic studies in portal hypertensive rat models. 相似文献
317.
Rosalba Paesano Francesca Berlutti Miriam Pietropaoli Fabrizio Pantanella Enrica Pacifici William Goolsbee Piera Valenti 《Biometals》2010,23(3):411-417
Iron deficiency (ID) and iron deficiency anemia (IDA) are the most common iron disorders throughout the world. ID and IDA,
particularly caused by increased iron requirements during pregnancy, represent a high risk for preterm delivery, fetal growth
retardation, low birth weight, and inferior neonatal health. Oral administration of ferrous sulfate to cure ID and IDA in
pregnancy often fails to increase hematological parameters, causes adverse effects and increases inflammation. Recently, we
have demonstrated safety and efficacy of oral administration of 30% iron saturated bovine lactoferrin (bLf) in pregnant women
suffering from ID and IDA. Oral administration of bLf significantly increases the number of red blood cells, hemoglobin, total
serum iron and serum ferritin already after 30 days of the treatment. The increasing of hematological values by bLf is related
to the decrease of serum IL-6 and the increase of serum hepcidin, detected as prohepcidin, whereas ferrous sulfate increases
IL-6 and fails to increase hematological parameters and prohepcidin. bLf is a more effective and safer alternative than ferrous
sulfate for treating ID and IDA in pregnant women. 相似文献
318.
Luigi Rosa Antimo Cutone Maria Stefania Lepanto Mellani Jinnett Scotti Maria Pia Conte Rosalba Paesano Piera Valenti 《Biometals》2018,31(3):301-312
Human and bovine lactoferrin (hLf and bLf) are multifunctional iron-binding glycoprotein constitutively synthesized and secreted by glandular epithelial cells and by neutrophils following induction. HLf and bLf possess very high similarity of sequence. Therefore, most of the in vitro and in vivo studies are carried out with commercial bLf (cbLf), available in large quantities and recognized by Food and Drug Administration (FDA, USA) as a safe substance. Physico-chemical heterogeneity of different cbLf preparations influences their effectiveness. CbLf iron-saturation affects thermal stability and resistance to proteolysis. Moreover, other metal ions such as Al(III), Cu(II), Mg(II), Mn(II), Zn(II) are chelated by cbLf, even if at lower affinity than Fe(III). Ca(II) is also sequestered by the carboxylate groups of sialic acid present on glycan chains of cbLf thus provoking the release of LPS, contributing to bactericidal activity. Similarly to more than 50% of eukaryotic proteins, cbLf possesses five N-glycosylation sites, also contributing to the resistance to proteolysis and, putatively, to the protection of intestinal mucosa from pathogens. CbLfs possess several functions as anti-microbial, anti-biofilm, anti-adhesive, anti-invasive and anti-inflammatory activities. They are also relevant modulators of iron and inflammatory homeostasis. However, the efficacy of cbLfs in exerting several functions can be erratic mainly depending from integrity, degree of iron and other metal ions saturation, N-glycosylation sites and chains, desialylated forms, Ca(II) sequestration, presence of contaminants and finally the ability to enter inside nucleus. 相似文献
319.
Magda Marchetti Silvia Pisani Giovanni Antonini Piera Valenti Lucilla Seganti Nicola Orsi 《Biometals》1998,11(2):89-94
The inhibitory effect of bovine lactoferrin (BLf) saturated with ferric, manganese or zinc ions, on the infection of Vero cells by human herpes simplex virus type 1 (HSV1) and 2 (HSV2) was investigated. Viral infectivity determined by intracellular antigen synthesis and plaque formation was efficiently inhibited by metal saturated lactoferrins in a dose-dependent manner. Effective BLf concentrations which reduced the infection by 50% ranged from 5.2 to 31 mug ml and were far below the cytotoxicity threshold. Fe BLf and Mn BLf exhibited selectivity indexes higher than Zn BLf and apoBLf for both viruses and the effect was mainly directed towards the early steps of infection. The slight viral inhibition shown by the citrate complexes of the different metals could indicate that the antiviral effect was not significantly influenced by Fe , Mn or Zn ions delivered by BLf into the cells. © Rapid Science 1998 相似文献