全文获取类型
收费全文 | 2632篇 |
免费 | 233篇 |
专业分类
2865篇 |
出版年
2023年 | 10篇 |
2022年 | 27篇 |
2021年 | 41篇 |
2020年 | 38篇 |
2019年 | 44篇 |
2018年 | 51篇 |
2017年 | 46篇 |
2016年 | 57篇 |
2015年 | 124篇 |
2014年 | 124篇 |
2013年 | 159篇 |
2012年 | 175篇 |
2011年 | 196篇 |
2010年 | 139篇 |
2009年 | 117篇 |
2008年 | 148篇 |
2007年 | 174篇 |
2006年 | 161篇 |
2005年 | 155篇 |
2004年 | 196篇 |
2003年 | 151篇 |
2002年 | 112篇 |
2001年 | 23篇 |
2000年 | 14篇 |
1999年 | 26篇 |
1998年 | 50篇 |
1997年 | 28篇 |
1996年 | 27篇 |
1995年 | 15篇 |
1994年 | 29篇 |
1993年 | 24篇 |
1992年 | 10篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 12篇 |
1988年 | 10篇 |
1987年 | 17篇 |
1986年 | 12篇 |
1985年 | 13篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 5篇 |
1978年 | 9篇 |
1976年 | 4篇 |
1974年 | 7篇 |
1973年 | 3篇 |
1971年 | 3篇 |
1962年 | 3篇 |
排序方式: 共有2865条查询结果,搜索用时 0 毫秒
31.
Jill E. Maddison Wendy E. J. Watson Peter R. Dodd Graham A. R. Johnston 《Journal of neurochemistry》1991,56(6):1881-1888
Excitatory amino acid receptor binding parameters were investigated in a spontaneous dog model of chronic hepatic encephalopathy. L-[3H]Glutamate, (+)-[3H]-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-im ine maleate ([3H]MK-801), [3H]kainate, and alpha-[3H]-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid ([3H]AMPA) binding experiments were performed using crude cerebrocortical synaptosomal membrane preparations from dogs with congenital portosystemic encephalopathy (PSE) and control dogs. There was no change in the affinity or density of L-[3H]-glutamate or [3H]MK-801 binding sites in dogs with congenital PSE compared with control dogs. However, in the PSE dogs there was a significant reduction in the density of [3H]kainate binding sites compared with control dogs and abolition of the low-affinity [3H]AMPA binding site. The relative binding capacity of PSE synaptosomal membranes for [3H]kainate and [3H]AMPA was expressed as the ratio Bmax/KD. There was a significant inverse correlation between the Bmax/KD ratio for [3H]AMPA binding and the worst grade of encephalopathy experienced by each dog. These results suggest that there is a significant perturbation of cerebrocortical non-N-methyl-D-aspartate receptor binding in dogs with congenital PSE which may have relevance to the pathogenesis of hepatic encephalopathy. 相似文献
32.
33.
William H.R. Langridge Robert R. Granados Jill F. Greenberg 《Journal of invertebrate pathology》1981,38(2):242-250
The structural proteins of Autographa californica (AcMNPV) and Heliothis zea (HzSNPV) nuclear polyhedrosis viruses were detected by indirect enzyme-linked immunosorbent assay (ELISA). The immunoassay detected less than 1 ng of AcMNPV protein. The extent of immunological relatedness between AcMNPV-occluded virus and AcMNPV polyhedral protein, AcMNPV-nonoccluded virus, Estigmene acrea granulosis virus, Amsacta moorei entomopoxvirus Heliothis zea NPV, and Lymantria dispar NPV was determined. No immunological relatedless was detected between HzSNPV, AcMNPV, and a persistent rod-shaped virus isolated from the Heliothis zea cell line (IMC-Hz-1). The polyhedral proteins of HzSNPV and AcMNPV were found to be immunologically identical. 相似文献
34.
Cycloheximide, colchicine, tunicamycin, glucagon, dibutyryl-3′–5′-cyclic AMP, dexamethasone and hydrocortisone had no effect on the lipoprotein lipase activity associated with rat cardiac muscle cells incubated . However, the steroid hormones and inhibitors affected profoundly the appearance of extracellular enzyme during the incubations. The pattern of effects, was consistent with lipoprotein lipase being a normal secretory product of heart muscle cells. 相似文献
35.
36.
37.
38.
The DNA content of spermatids of mice carrying Cattanach's translocation has been measured with high precision by flow cytometry. The observation that the two peaks of DNA content in the haploid region of the DNA histograms represent X-and Y-bearing spermatids was tested and confirmed. Using flow cytometry, the difference in DNA content between the X and Y chromosomes in these mice was measured to be 5.2±0.1% of the total haploid genome as compared to 3.4±0.1% in normal mice. These results demonstrated the precision of flow cytometry for cytogenetic studies. Additional information on spermatogenesis in mice bearing Cattanach's translocation was obtained and showed a gradual loss of cells during spermatogenesis in those bearing the balanced form of the translocation. 相似文献
39.
The permeability of the blood-brain barrier to several classes of compounds was studied in rats between the ages of 15 days and 9 weeks. 14C-labelled test substances were injected simultaneously with two reference isotopes, 3H2O and 113mIn-labelled EDTA, into the common carotid artery followed by decapitation 10 s later.There was evidence that a monocarboxylic acid transport system in 15 to 23 day-old rats had a capacity at least six times greater than that present in adult animals. l-Lactate and acetate showed the highest permeability. At all ages there was a constant ratio between l-lactate and (−)d-3-hydroxybutyrate values. d-Glucose permeability increased with age, while that of several amino acids tested was the same in young and adults rats. 相似文献
40.
Bror Edlund Jill Andersson Vincent Titanji Ulla Dahlqvist Pia Ekman Örjan Zetterqvist Lorentz Engström 《Biochemical and biophysical research communications》1975,67(4):1516-1521
One dominating peptic phosphopeptide, Asx-Thr-Lys-Gly-Pro-Glx-Ile-Glx-Thr-Gly-Val-Leu-Arg-Arg-Ala-(32P)SerP-Val-Ala-Glx-Leu, was obtained from rat liver pyruvate kinase (type L) phosphorylated by cyclic 3′,5′-AMP-stimulated protein kinase from the same tissue. The sequence around the phosphorylated serine residue is similar to that of a corresponding but smaller peptic phosphopeptide previously isolated from pig liver (type L) pyruvate kinase, Leu-Arg-Arg-Ala-(32P)SerP-Leu. 相似文献