全文获取类型
收费全文 | 2043篇 |
免费 | 154篇 |
国内免费 | 1篇 |
出版年
2023年 | 7篇 |
2022年 | 6篇 |
2021年 | 18篇 |
2020年 | 12篇 |
2019年 | 21篇 |
2018年 | 28篇 |
2017年 | 38篇 |
2016年 | 55篇 |
2015年 | 54篇 |
2014年 | 82篇 |
2013年 | 117篇 |
2012年 | 122篇 |
2011年 | 124篇 |
2010年 | 87篇 |
2009年 | 85篇 |
2008年 | 109篇 |
2007年 | 126篇 |
2006年 | 145篇 |
2005年 | 125篇 |
2004年 | 144篇 |
2003年 | 152篇 |
2002年 | 166篇 |
2001年 | 24篇 |
2000年 | 28篇 |
1999年 | 33篇 |
1998年 | 30篇 |
1997年 | 27篇 |
1996年 | 19篇 |
1995年 | 18篇 |
1994年 | 24篇 |
1993年 | 10篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 15篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 17篇 |
1983年 | 11篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有2198条查询结果,搜索用时 15 毫秒
1.
Julie A. Harris Akihiko Koyama Sumihiro Maeda Kaitlyn Ho Nino Devidze Dena B. Dubal Gui-Qiu Yu Eliezer Masliah Lennart Mucke 《PloS one》2012,7(9)
Accumulation of hyperphosphorylated tau in the entorhinal cortex (EC) is one of the earliest pathological hallmarks in patients with Alzheimer’s disease (AD). It can occur before significant Aβ deposition and appears to “spread” into anatomically connected brain regions. To determine whether this early-stage pathology is sufficient to cause disease progression and cognitive decline in experimental models, we overexpressed mutant human tau (hTauP301L) predominantly in layer II/III neurons of the mouse EC. Cognitive functions remained normal in mice at 4, 8, 12 and 16 months of age, despite early and extensive tau accumulation in the EC. Perforant path (PP) axon terminals within the dentate gyrus (DG) contained abnormal conformations of tau even in young EC-hTau mice, and phosphorylated tau increased with age in both the EC and PP. In old mice, ultrastructural alterations in presynaptic terminals were observed at PP-to-granule cell synapses. Phosphorylated tau was more abundant in presynaptic than postsynaptic elements. Human and pathological tau was also detected within hippocampal neurons of this mouse model. Thus, hTauP301L accumulation predominantly in the EC and related presynaptic pathology in hippocampal circuits was not sufficient to cause robust cognitive deficits within the age range analyzed here. 相似文献
2.
James M. Mason Nita N. Scobie Akihiko H. Yamamoto 《Molecular & general genetics : MGG》1989,215(2):190-199
Summary The mutagen-sensitive mutant mus(1)104
D1
of Drosophila melanogaster maps to a position on the X chromosome very close to the meiotic mutant mei-41
D5
. Both mutants have been characterized as mutagen-sensitive and defective in post-replication repair. In the present report we show by complementation studies that mus(1)104 and mus(1)103 are allelic with mei-41. In addition, two reported alleles of mus(1)104 lie between the mei-41 alleles A10 and D5. The size of the mei-41 locus is estimated to be about 0.1 centimorgans (cM). Because several alleles of mei-41 have been shown to reduce recombination and increase meiotic chromosome loss and nondisjunction, mus(1)104
D1
females were examined for defects in meiosis. Although there was no evidence for reduced recombination on the second chromosome in homozygous mus(1)104
D1
females, heterozygous mus(1)104
D1
/mei-41
>D5
and mus(1)104
D1
/deficiency females showed reduced levels of recombination. However, there was no evidence of an increase in nondijunction in these females.We dedicate this article to the memory of Larry Sandler, who passed away suddenly on February 7, 1987 相似文献
3.
Summary Biosynthesis and processing of the protective protein for -galactosidase in normal and galactosialidosis fibroblasts were investigated using specific antiserum preparations. A 45-kd precursor was processed to a mature 30-kd protein in normal fibroblasts. The mature protective protein was not detected in any of the twelve galactosialidosis fibroblast strains examined in this study. The precursor was not detected in two cases and in the others was of heterogeneous molecular weight, i.e., normal, abnormally low, or abnormally high. These molecular abnormalities were not correlated with clinical manifestations of the patients. 相似文献
4.
J Nakagawa D von der Ahe D Pearson B A Hemmings S Shibahara Y Nagamine 《The Journal of biological chemistry》1988,263(5):2460-2468
5.
6.
Cloning and sequence analysis of cDNA for rat corticotropin-releasing factor precursor 总被引:12,自引:0,他引:12
H Jingami N Mizuno H Takahashi S Shibahara Y Furutani H Imura S Numa 《FEBS letters》1985,191(1):63-66
DNA complementary to the rat hypothalamic mRNA coding for the corticotropin-releasing factor precursor (prepro-CRF) has been cloned by screening a cDNA library with a human genomic DNA probe. Nucleotide sequence analysis of the cloned cDNA has revealed that rat prepro-CRF consists of 187 amino acid residues including a putative signal peptide. The CRF and putative signal peptide regions are more highly conserved among rat, human and ovine prepro-CRF than is the cryptic portion. 相似文献
7.
Cloning and sequence analysis of human genomic DNA encoding gamma subunit precursor of muscle acetylcholine receptor 总被引:14,自引:0,他引:14
S Shibahara T Kubo H J Perski H Takahashi M Noda S Numa 《European journal of biochemistry》1985,146(1):15-22
The limited proteolysis of human low-molecular-mass kininogen by kallikrein from tissue sources has been studied. Porcine pancreatic kallikrein applied in catalytic amounts split the kininogen molecule (apparent mass 68 kDa) with the release of lysyl-bradykinin (1 kDa). This generated a nicked kininogen molecule with a heavy chain and light chain interconnected via disulfide bridging. Following reductive cleavage of the disulfide bonds, the heavy chain of apparent mass 62 kDa was isolated by preparative sodium dodecyl sulfate electrophoresis, and the light chain of 5 kDa by reversed-phase high-performance liquid chromatography. The light chain was found to be composed of 38 amino acids with a single half-cystine residue. Amino-terminal sequence analysis revealed that the light chain is derived from the carboxy terminus of the kininogen molecule [Lottspeich et al. (1984) Eur. J. Biochem. 142, 227-232]. Immunological characterization of the isolated L chain indicated that it harbours antigenic site(s) unique for low-Mr kininogen as well as sites common to high-Mr and low-Mr kininogen. 相似文献
8.
“Bulk density” and “dry-matter content” are useful indices of dry-matter accumulation in plant organs. A theoretical equation
describing the relationship between these two indices was put forward. To examine the reliability of this equation, the seasonal
changes of these two indices were investigated in the leaves and stems of different ages ofAucuba japonica. In each organ both indices varied seasonally almost parallel to each other, but the seasonal changes of dry-matter content
were less obvious than those of bulk density. The observed bulk density was always larger than that calculated from the observed
dry-matter content by the theoretical equation. A drying experiment showed that this discrepancy was caused by the decrement
of the volume of the plant material by water loss during the period from the weight measurement to the volume measurement.
When the water loss was negligible, the equation described well the relationships between the two indices of the experimental
materials. It was also shown that this equation was useful for the estimation of the amount of air space in plant materials. 相似文献
9.
Satoshi Yoshida Masazumi Takeshita Akihiko Kawaguchi 《Biochemical and biophysical research communications》1984,124(2):322-328
The elongation of arachidoyl-CoA by swine cerebral microsomes resulted in the production of behenic acid (22:0) and lignoceric acid (24:0) concomitantly. When 4S-[4-2H1]NADPH was used for the elongation of arachidoyl-CoA, the incorporation of two deuterium atoms into 22:0 was observed by the technique of mass fragmentography. Furthermore, the incorporation of four deuterium atoms into 24:0 was also detected. On the other hand, when 4R-[4-2H1]NADPH was used, no deuterium was incorporated into the elongated products. 相似文献
10.