全文获取类型
收费全文 | 15202篇 |
免费 | 1441篇 |
国内免费 | 13篇 |
专业分类
16656篇 |
出版年
2023年 | 67篇 |
2022年 | 137篇 |
2021年 | 287篇 |
2020年 | 127篇 |
2019年 | 182篇 |
2018年 | 264篇 |
2017年 | 206篇 |
2016年 | 340篇 |
2015年 | 605篇 |
2014年 | 695篇 |
2013年 | 923篇 |
2012年 | 1069篇 |
2011年 | 1088篇 |
2010年 | 698篇 |
2009年 | 593篇 |
2008年 | 915篇 |
2007年 | 942篇 |
2006年 | 837篇 |
2005年 | 810篇 |
2004年 | 803篇 |
2003年 | 774篇 |
2002年 | 679篇 |
2001年 | 215篇 |
2000年 | 180篇 |
1999年 | 235篇 |
1998年 | 203篇 |
1997年 | 142篇 |
1996年 | 117篇 |
1995年 | 132篇 |
1994年 | 138篇 |
1993年 | 123篇 |
1992年 | 153篇 |
1991年 | 107篇 |
1990年 | 121篇 |
1989年 | 121篇 |
1988年 | 104篇 |
1987年 | 95篇 |
1986年 | 86篇 |
1985年 | 84篇 |
1984年 | 82篇 |
1983年 | 81篇 |
1982年 | 67篇 |
1981年 | 69篇 |
1980年 | 71篇 |
1979年 | 84篇 |
1978年 | 54篇 |
1977年 | 50篇 |
1974年 | 58篇 |
1973年 | 53篇 |
1970年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
991.
Yvonne H. Edwards Sue Povey Kay M. Levan Catherine E. Driscoll Jose Luis Millan Erwin Goldberg 《Genesis (New York, N.Y. : 2000)》1987,8(4):219-232
From the data presented in this report, the human LDHC gene locus is assigned to chromosome 11. Three genes determine lactate dehydrogenase (LDH) in man. LDHA and LDHB are expressed in most somatic tissues, while expression of LDHC is confined to the germinal epithelium of the testes. A human LDHC cDNA clone was used as a probe to analyze genomic DNA from rodent/human somatic cell hybrids. The pattern of bands with LDHC hybridization is easily distinguished from the pattern detected by LDHA hybridization, and the LDHC probe is specific for testis mRNA. The structural gene LDHA has been previously assigned to human chromosome 11, while LDHB maps to chromosome 12. Studies of pigeon LDH have shown tight linkage between LDHB and LDHC leading to the expectation that these genes would be syntenic in man. However, the data presented in this paper show conclusively that LDHC is syntenic with LDHA on human chromosome 11. The terminology for LDH genes LDHA, LDHB, and LDHC is equivalent to Ldhl, Ldh2, and Ldh3, respectively. 相似文献
992.
The genus Afromantispa Snyman & Ohl, 2012 was recently synonymised with Mantispa Illiger, 1798 by Monserrat (2014). Here morphological evidence is presented in support of restoring the genus Afromantispa
stat. rev. to its previous status as a valid and morphologically distinct genus. Twelve new combinations (comb. n.) are proposed as species of Afromantispa including three new synonyms. 相似文献
993.
994.
995.
996.
997.
998.
999.
Catherine Strazielle Rozat Jazi Yann Verdier Sue Qian Robert Lalonde 《Neurochemistry international》2009,55(8):806-814
Mitochondrial dysfunction and brain metabolic alteration are early neurofunctional aspects in Alzheimer's disease (AD). Regional brain metabolism was analyzed by cytochrome c oxidase (COX) histochemistry in PS1-A246E mouse mutants, a model of autosomal dominant AD overexpressing beta-amyloid (Aβ) peptide without amyloidosis or cell degeneration. Immunohistochemical samples were analyzed on adjacent sections for regional Aβ1-42 levels, as well as DNA oxidative damage with 8-hydroxy-2-deoxyguanosine (8-OHdG). COX activity increased in the basal forebrain nuclear complex, specific parts of the amygdala and hippocampus, as well as in striatum and connected regions. On the contrary, a hypometabolism was observed in midline thalamic, interpeduncular, and pedonculopontine nuclei. The integration of these regions in circuitries subserving emotions, arousal, and cognitive functions may explain why neurochemical alterations in specific brain regions were linearly correlated with psychomotor slowing and disinhibition previously reported in the mutant. As the PS1-A246E model appears to mimick prodromal AD, the results support the existence of mitochondrial abnormalities prior to AD-related cognitive deficits. However, since affected PS1-A246E brain regions were not primarily those altered in AD-associated histopathological features and did not systematically display either Aβ overexpression or higher 8-OHdG immunolabelling, the hypermetabolism observed seems to comprise a compensatory reaction to early mitochondrial abnormalities; furthermore, neuronal synaptic function should be considered as particularly relevant in COX activity changes. 相似文献
1000.