全文获取类型
收费全文 | 7062篇 |
免费 | 428篇 |
出版年
2023年 | 53篇 |
2022年 | 73篇 |
2021年 | 178篇 |
2020年 | 114篇 |
2019年 | 135篇 |
2018年 | 201篇 |
2017年 | 144篇 |
2016年 | 229篇 |
2015年 | 377篇 |
2014年 | 356篇 |
2013年 | 531篇 |
2012年 | 578篇 |
2011年 | 557篇 |
2010年 | 352篇 |
2009年 | 329篇 |
2008年 | 395篇 |
2007年 | 389篇 |
2006年 | 389篇 |
2005年 | 364篇 |
2004年 | 330篇 |
2003年 | 286篇 |
2002年 | 286篇 |
2001年 | 49篇 |
2000年 | 34篇 |
1999年 | 48篇 |
1998年 | 61篇 |
1997年 | 65篇 |
1996年 | 34篇 |
1995年 | 51篇 |
1994年 | 43篇 |
1993年 | 34篇 |
1992年 | 26篇 |
1991年 | 34篇 |
1990年 | 17篇 |
1989年 | 19篇 |
1988年 | 25篇 |
1987年 | 19篇 |
1986年 | 9篇 |
1985年 | 19篇 |
1984年 | 32篇 |
1983年 | 17篇 |
1982年 | 19篇 |
1981年 | 24篇 |
1980年 | 23篇 |
1979年 | 18篇 |
1978年 | 17篇 |
1977年 | 13篇 |
1976年 | 11篇 |
1974年 | 9篇 |
1965年 | 9篇 |
排序方式: 共有7490条查询结果,搜索用时 15 毫秒
41.
Elizabeth R. Fielding David B. Archer Everly Conway de Macario Alberto J. L. Macario 《Applied microbiology》1988,54(3):835-836
Methanogenic bacteria were isolated from landfill sites in the United Kingdom. Strains of Methanobacterium formicicum, Methanosarcina barkeri, several different immunotypes of Methanobacterium bryantii, and a coccoid methanogen distinct from the reference immunotypes were identified. 相似文献
42.
Summary A simple device is described for con-trolled feeding of pasty materials in laboratory scale fed-batch cultures. The device
was tested with apple pomace as raw material for production of microbial biomass, using the level of dissolved oxygen as controlled
parameter. 相似文献
43.
Dr. Alfonso Ruiz-Bravo María Jimenez-Valera Gerardo Alvarez de Cienfuegos Khalil Kouwatli Alberto Ramos-Cormenzana 《Current microbiology》1986,13(6):313-316
Twelve strains ofYersinia enterocolitica were examined for their ability to bind spontaneously to murine leukocytes. Each of eight HeLa cell invasive strains exhibited nonselective binding to peritoneal leukocytes, lymph node leukocytes, and thymocytes, whereas four noninvasive strains lacked binding properties. Like the HeLa cell invasion, the binding ofY. enterocolitica to leukocytes was much less efficient for bacteria grown at 37°C than for bacteria grown at 22°C. The binding properties were not influenced by the virulence plasmid that codes for Vwa+ phenotype. This leukocyte binding test is proposed as a simple assay for invasive properties ofY. enterocolitica. 相似文献
44.
Jorgina Satrustegui Juan Bautista Alberto Machado 《Molecular and cellular biochemistry》1983,51(2):123-127
Summary The utilization by yeast of two carbon sources is carried out through the operation of the glyoxylic acid cycle. Kinetic data from the isocitrate transforming enzymes suggest that the flow of isocitrate through the glyoxylic acid cycle depends upon the inhibition of the isocitrate decarboxylating enzymes. Both isocitrate dehydrogenases are inhibited by a mixture of glyoxylate + oxaloacetate, but for the reasons described in the text we consider that this inhibition is of no physiological significance. On the other hand, we have found that NADPH is a competitive inhibitor of NADP-isocitrate dehydrogenase with respect to NADP+, with a KI similar to its KM. It also produces an additive effect on the NADH-produced inhibition of NAD-isocitrate dehydrogenase. We propose NADPH as the compound that channels the utilization of isocitrate into the glyoxylic acid cycle. This is supported by the finding of an increased NADPH/NADP+ ratio in acetate grown yeast with respect to glucose grown cells. 相似文献
45.
Ana Rosa Santa Cruza Luis A. Quesada Allue Alberto Baldi 《Molecular and cellular biochemistry》1983,56(1):55-66
Microsomal preparations from malignant human breast tumors catalyzed the transfer of mannose and glucose from GDP-[14C]-Man and UDP-[14C]-Glc into lipid-linked sugars and glycoprotein-like substances. As judged by several criteria the obtained lipid-linked monosaccharides behaved as dolichyl phosphate mannose and dolichyl phosphate glucose whereas lipid-linked oligosaccharides behaved as polyprenyl diphosphate derivatives. The optimum conditions for mannosyl- and glucosyl-transfer reactions and the effect of dolichyl phosphate, detergent and EDTA on incubation mixture were described. 相似文献
46.
47.
48.
49.
A. I. Macdougall G. J. Addis N. Mackay I. W. Dymock A. G. G. Turpie D. L. K. Ballingall W. J. Maclennan B. Whiting J. G. Macarthur 《BMJ (Clinical research ed.)》1970,3(5720):440-442
Clonidine, in a daily dosage of 0·15-4·8 mg., effectively lowered systolic and diastolic pressures in 26 out of 28 impatients with moderate to severe hypertension, including five with primary renal disease. The action of the drug did not depend on posture and was not associated with reduction in renal function. Side-effects were not severe, but mental changes occurred in four patients.Clonidine is a useful alternative to currently available antihypertensive drugs, but further evaluation of its longterm efficacy is required. 相似文献
50.
Capillary GC quantification of cholesterol oxidation products in plasma lipoproteins of fasted humans 总被引:5,自引:0,他引:5
Cholesterol oxidation products have been hypothesized to be important factors in atherosclerosis, a process which can culminate in myocardial infarction. The relative importance of exogenous or in vivo sources of cholesterol oxidation products has not been determined. However, methodology used for cholesterol oxidation products analysis of foods is applicable to the determination of cholesterol oxidation products in human plasma lipoproteins. Such methodology, outlined in this report, permits numerous critical experiments to be conducted on the possible role of cholesterol oxidation products in coronary heart disease. 相似文献