全文获取类型
收费全文 | 4491篇 |
免费 | 372篇 |
出版年
2023年 | 38篇 |
2022年 | 86篇 |
2021年 | 129篇 |
2020年 | 81篇 |
2019年 | 104篇 |
2018年 | 145篇 |
2017年 | 112篇 |
2016年 | 185篇 |
2015年 | 275篇 |
2014年 | 244篇 |
2013年 | 338篇 |
2012年 | 394篇 |
2011年 | 384篇 |
2010年 | 192篇 |
2009年 | 180篇 |
2008年 | 247篇 |
2007年 | 239篇 |
2006年 | 213篇 |
2005年 | 180篇 |
2004年 | 167篇 |
2003年 | 155篇 |
2002年 | 160篇 |
2001年 | 61篇 |
2000年 | 35篇 |
1999年 | 47篇 |
1998年 | 41篇 |
1997年 | 35篇 |
1996年 | 31篇 |
1995年 | 20篇 |
1994年 | 17篇 |
1993年 | 12篇 |
1992年 | 17篇 |
1991年 | 22篇 |
1990年 | 26篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 17篇 |
1986年 | 11篇 |
1985年 | 19篇 |
1984年 | 18篇 |
1983年 | 17篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 8篇 |
1979年 | 12篇 |
1975年 | 9篇 |
1974年 | 13篇 |
1973年 | 11篇 |
1968年 | 9篇 |
1966年 | 7篇 |
排序方式: 共有4863条查询结果,搜索用时 17 毫秒
51.
Alessandro Viggiano Davide Viggiano Andrea Viggiano Bruno De Luca 《The journal of histochemistry and cytochemistry》2003,51(7):865-871
Superoxide anions are highly reactive radicals overproduced in many pathological situations such as inflammation and ischemia. One of the major factors in the protection from superoxide anions is the enzyme superoxide dismutase (SOD), which catalyzes the dismutation of superoxide to hydrogen peroxide. This study presents a quantitative histochemical method to estimate SOD activity in rat brain tissue sections. This method is based on the cerium capture method and 3,3'-diaminobenzidine amplification of transition cerium compounds. Substrate for SOD was provided by reduction of oxygen during the autoxidation of riboflavin in the presence of UV light. This histochemical method reveals the overall activity of the three different forms of SOD described in mammalian tissues: cytosolic copper-zinc SOD, mitochondrial manganese SOD, and the high molecular weight extracellular SOD. Eventually, this method can be used to quantify SOD activity in tissue sections by image analysis. 相似文献
52.
Giuseppe Comi Corrado Pipan Giuseppe Botta Luca Cocolin Carlo Cantoni Marisa Manzano 《FEMS immunology and medical microbiology》1996,16(1):45-49
Abstract A combined polymerase chain reaction and restriction endonuclease (RE) enzyme assay was developed to discriminate between Campylobacter coli and Campylobacter jejuni . Amplimers of the FlaA gene obtained by PCR were digested with Alu I and Hin fI to distinguish C. coli from C. jejuni . With Alu I digestion C. jejuni -specific bands were observed at 110, 140 and 160 bp and C. coli -specific bands at 293 and 147 bp. C. jejuni -specific bands of 349 and 109 bp were found by Hin fI digestion but Hin fI did not digest the Fla A amplimer of C. coli . This combined technique is fast and easy to perform, and distinguishes the two campylobacters unequivocally. 相似文献
53.
Raymond R. Padua Rajat Sethi Naranjan S. Dhalla Elissavet Kardami 《Molecular and cellular biochemistry》1995,143(2):129-135
To examine whether basic fibroblast growth factor (bFGF) administered to the heart by perfusion can improve cardiac resistance to injury we employed an isolated rat heart model of ischemia-reperfusion injury and determined the extent of functional recovery in bFGF-treated and control hearts. Global ischemia was simulated by interruption of flow for 60 min. Recovery of developed force of contraction (DF), recorded after reestablishment of flow for 30 min, reached 63.8±1.5% and 96.5±3.5% of preischemic levels in control and bFGF-treated hearts (10 g/heart), respectively, indicating that bFGF induced significantly improved recovery of mechanical function. Recoveries of the rates of contraction or relaxation were also significantly improved in bFGF-treated hearts. Extent of myocardial injury, assessed by determination of phosphocreatine kinase in the effluent, was reduced as a result of bFGF treatment. As a first step towards understanding the mechanism and direct cellular target(s) of bFGF-induced cardioprotection, we investigated its fate after perfusion. Perfusion of 10 g bFGF/heart resulted in a 4-fold increase in bFGF associated with the heart compared to control levels, as estimated by biochemical fractionation and immunoblotting. Immunofluorescent staining of the bFGF-perfused hearts revealed intense anti-bFGF staining in association with blood vessels as well as the periphery of cardiomyocytes, suggesting that the latter may be a target for direct bFGF action. In conclusion, our findings of bFGF-induced increases in cardiac resistance to, and improved functional recovery from, ischemia-reperfusion injury indicate that bFGF may have clinical applications in the treatment of ischemic heart disease. 相似文献
54.
High Mobility Group 1 Protein Is Not Stably Associated with the Chromosomes of Somatic Cells 总被引:11,自引:1,他引:10 下载免费PDF全文
Luca Falciola Fabio Spada Sabina Calogero Gernot Lngst Renate Voit Ingrid Grummt Marco E. Bianchi 《The Journal of cell biology》1997,137(1):19-26
High mobility group 1 (HMG1) protein is an abundant and conserved component of vertebrate nuclei and has been proposed to play a structural role in chromatin organization, possibly similar to that of histone H1. However, a high abundance of HMG1 had also been reported in the cytoplasm and on the surface of mammalian cells. We conclusively show that HMG1 is a nuclear protein, since several different anti-HMG1 antibodies stain the nucleoplasm of cultured cells, and epitope-tagged HMG1 is localized in the nucleus only. The protein is excluded from nucleoli and is not associated to specific nuclear structures but rather appears to be uniformly distributed. HMG1 can bind in vitro to reconstituted core nucleosomes but is not stably associated to chromatin in live cells. At metaphase, HMG1 is detached from condensed chromosomes, contrary to histone H1. During interphase, HMG1 readily diffuses out of nuclei after permeabilization of the nuclear membranes with detergents, whereas histone H1 remains associated to chromatin. These properties exclude a shared function for HMG1 and H1 in differentiated cells, in spite of their similar biochemical properties. HMG1 may be stably associated only to a very minor population of nucleosomes or may interact transiently with nucleosomes during dynamic processes of chromatin remodeling. 相似文献
55.
P Zamboni M Persichella G Siro-Brigiani A De Luca 《Bollettino della Società italiana di biologia sperimentale》1984,60(7):1377-1379
A reduction of the thirst was observed one hour after intramuscolar injection of 0.3 mg/kg propranolol in the rat; this effect was not observed with higher doses. According to work hypotheses, small doses could act blocking renal beta-adrenergic receptors: the stopped renin emission reduces angiotensin production that is the basic factor of thirst. The AA hypothesize that the lack of the effect in response to higher doses of propranolol can be explained through a different action of this drug which antagonizes the first one. 相似文献
56.
R De Luca A Renzulli V Di Donna A Sicuranza C Sellitto P Mangano L Iovino 《Bollettino della Società italiana di biologia sperimentale》1984,60(4):739-744
In this research we have determined the behaviour of proteic plasmatic pattern and some enzymes during extracorporeal circulation and we noted a constant increase of albumin and of the ratio Alb/Glob. We observed also variations of some enzymes. Our opinion according other AA. is that this changes are determined principally by the large dose of heparin necessary during the C.E.C. 相似文献
57.
Separation of mannosylretinylphosphate from dolichylmannosylphosphate by chromatography on columns of DEAE-sephacel 总被引:2,自引:0,他引:2
A one-step column chromatographic procedure on DEAE-Sephacel allows the separation of mannosylretinylphosphate from dolichylmannosylphosphate with minimal breakdown of the mannosylretinylphosphate. Using this procedure, subcellular fractions of rat liver were shown to be active in synthesizing both mannolipids from GDP-[14C]mannose in the absence or presence of exogenous retinylphosphate. 相似文献
58.
P V Bhat L M De Luca S Adamo I Akalovsky C S Silverman-Jones G L Peck 《Journal of lipid research》1979,20(3):357-362
Spontaneously transformed mouse fibroblasts (Balb/c 3T12-3 cells) displayed an increased adhesion when cultured in the presence of 10(-6) M all-trans retinol and acquired morphological characteristics of the normal phenotype. Thus it was of interest to investigate the metabolism of [15-(14)C]retinol in this system. Within 24 hours of culture, approximately 4.25% of the [(14)C]retinol was taken up by the cells. The hydrocarbon [(14)C]anhydroretinol was a major metabolic product and was identified by gas-liquid chromatography and by its typical ultraviolet absorption spectrum with maxima at 386, 364, and 346 nm. At 24 and 40 hours anhydroretinol represented 27% and 55%, respectively, of the total nonpolar metabolites or approximately 16% and 30% of the total radioactive products. Formalin-fixed fibroblasts or cultured intestinal mucosal cells did not convert retinol into anhydroretinol. A more polar product with a UV absorption maximum at 310 nm was also found. The time course of the synthesis of this product by 3T12 cells suggested a precursor-product relationship with anhydroretinol. A microsomal preparation from 3T12 cells was also active in synthesizing [(14)C]anhydroretinol and [(14)C]metabolite-310 from [(14)C]retinol. Moreover incubation of metabolite-310 with the 3T12 microsomes yielded anhydroretinol (40% conversion in 30 minutes), suggesting that metabolite-310 is an intermediate in the synthesis of anhydroretinol by these cells. Anhydroretinol appears to be an end product of the metabolism of retinol in 3T12-3 cells, as suggested by the finding that over 90% of [(14)C]anhydroretinol incubated for 30 hours with 3T12-3 cells was recovered unaltered, without the formation of detectable retroretinol, retinol, or retinoic acid.-Bhat, P. V., L. M. De Luca, S. Adamo, I. Akalovsky, C. S. Silverman-Jones, and G. L. Peck. Retinoid metabolism in spontaneously transformed mouse fibroblasts (Balb/c 3T12-3 cells): enzymatic conversion of retinol to anhydroretinol. 相似文献
59.
Henry R. Black Samuel O. Thier Philip F. Felig James F. Jekel Joseph Belsky James L. Bernene Everett Cooper Vincent A. De Luca Jr. Martin H. Floch Marvin Garrell Pasquale E. Perillie Robert L. Piscatelli George F. Thornton 《The Yale journal of biology and medicine》1977,50(6):637-644
In July, 1975, the Departments of Internal Medicine at the Yale University School of Medicine and eight community hospitals in southern and western Connecticut formed the Yale Affiliated Hospital Program (YAHP) in Internal Medicine. The YAHP provides a planned and focused program of continuing education for medical staff and housestaff at the affiliated hospitals. Six formats for the over 1,000 rounds, lectures, and conferences given annually are used. The members of the YAHP also cooperate in housestaff and faculty recruiting, evaluation of quality of care and evaluation of the process of continuing medical education itself. This report summarizes the organization, goals and future plans of the YAHP. 相似文献
60.
M Gemelli R Manganaro F De Luca C Imperatore G Costa C Mamì 《Hormones et métabolisme》1992,24(1):39-41
In order to clarify whether an interaction between endogenous opioids and feeding occurs at birth, we studied Beta-endorphin (beta-EP) and ACTH plasma levels in response to a feed of 10% glucose, or formula, in 120 healthy full-term infants. Neither postprandial beta-EP nor ACTH increases were found at the 24th hour or on the fourth day of life. beta-EP physiology in newborn infants seems to be different from adults. 相似文献