全文获取类型
收费全文 | 12418篇 |
免费 | 1110篇 |
国内免费 | 2篇 |
出版年
2023年 | 84篇 |
2022年 | 200篇 |
2021年 | 374篇 |
2020年 | 261篇 |
2019年 | 312篇 |
2018年 | 371篇 |
2017年 | 346篇 |
2016年 | 473篇 |
2015年 | 643篇 |
2014年 | 724篇 |
2013年 | 851篇 |
2012年 | 918篇 |
2011年 | 891篇 |
2010年 | 549篇 |
2009年 | 503篇 |
2008年 | 576篇 |
2007年 | 550篇 |
2006年 | 464篇 |
2005年 | 441篇 |
2004年 | 373篇 |
2003年 | 347篇 |
2002年 | 314篇 |
2001年 | 259篇 |
2000年 | 249篇 |
1999年 | 201篇 |
1998年 | 100篇 |
1997年 | 113篇 |
1996年 | 95篇 |
1995年 | 76篇 |
1994年 | 94篇 |
1993年 | 70篇 |
1992年 | 121篇 |
1991年 | 114篇 |
1990年 | 106篇 |
1989年 | 94篇 |
1988年 | 74篇 |
1987年 | 87篇 |
1986年 | 106篇 |
1985年 | 77篇 |
1984年 | 64篇 |
1983年 | 59篇 |
1982年 | 59篇 |
1981年 | 53篇 |
1980年 | 40篇 |
1979年 | 48篇 |
1978年 | 53篇 |
1977年 | 66篇 |
1975年 | 54篇 |
1974年 | 39篇 |
1972年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Maturity Onset Diabetes of the Young (MODY) is a heterogeneous group of genetic diseases characterized by a primary defect in insulin secretion and hyperglycemia, non-ketotic disease, monogenic autosomal dominant mode of inheritance, age at onset less than 25 years, and lack of auto-antibodies. It accounts for 2–5% of all cases of non-type 1 diabetes. MODY subtype 2 is caused by mutations in the glucokinase (GCK) gene. In this study, we sequenced the GCK gene of two volunteers with clinical diagnosis for MODY2 and we were able to identify four mutations including one for a premature stop codon (c.76C>T). Based on these results, we have developed a specific PCR-RFLP assay to detect this mutation and tested 122 related volunteers from the same family. This mutation in the GCK gene was detected in 21 additional subjects who also had the clinical features of this genetic disease. In conclusion, we identified new GCK gene mutations in a Brazilian family of Italian descendance, with one due to a premature stop codon located in the second exon of the gene. We also developed a specific assay that is fast, cheap and reliable to detect this mutation. Finally, we built a molecular ancestry model based on our results for the migration of individuals carrying this genetic mutation from Northern Italy to Brazil. 相似文献
4.
A review of in vitro mutagenesis assessment of metal compounds in mammalian and nonmammalian test systems has been compiled.
Prokaryotic assays are ineffective or inconsistent in their detection of most metals as mutagens, with the notable exception
of hexavalent chromium. Mammalian assay systems appear to be similarly inappropriate for the screening of metal compounds
based upon the limited number of studies that have employed those compounds having known carcinogenic activity. Although of
limited value as screening tests for the detection of potentially carcinogenic metal compounds, the well-characterized in
vitro mutagenesis systems may prove to be of significant value as a means to elucidate mechanisms of metal genotoxicity. 相似文献
5.
Injection of manganese into the rat corpus striatum causes a rapid fall in the biopterin and dopamine (DA) content ipsilateral to the lesion. Two weeks after the lesion both biopterin and DA are partially recovered. Controls, injected with saline or magnesium, do not show alterations in their DA or cofactor levels. It is proposed that the fall in DA levels results from a rapid displacement of the amine from its storage sites by manganese followed by a decrease in the rate of DA synthesis causes by the drop in cofactor levels. 相似文献
6.
Lucas Henriques Viscardi Danilo Oliveira Imparato Maria Ctira Bortolini Rodrigo Juliani Siqueira Dalmolin 《Molecular biology and evolution》2021,38(3):735
The origin of nervous systems is a main theme in biology and its mechanisms are largely underlied by synaptic neurotransmission. One problem to explain synapse establishment is that synaptic orthologs are present in multiple aneural organisms. We questioned how the interactions among these elements evolved and to what extent it relates to our understanding of the nervous systems complexity. We identified the human neurotransmission gene network based on genes present in GABAergic, glutamatergic, serotonergic, dopaminergic, and cholinergic systems. The network comprises 321 human genes, 83 of which act exclusively in the nervous system. We reconstructed the evolutionary scenario of synapse emergence by looking for synaptic orthologs in 476 eukaryotes. The Human–Cnidaria common ancestor displayed a massive emergence of neuroexclusive genes, mainly ionotropic receptors, which might have been crucial to the evolution of synapses. Very few synaptic genes had their origin after the Human–Cnidaria common ancestor. We also identified a higher abundance of synaptic proteins in vertebrates, which suggests an increase in the synaptic network complexity of those organisms. 相似文献
7.
8.
9.
Spencer G. Lucas Bolat U. Bayshashov Lyubov A. Tyutkova Ayzhan K. Zhamangara Bolat Z. Aubekerov 《Pal?ontologische Zeitschrift》1997,71(3-4):305-314
At Aktau Mountain in the Ili depression of eastern Kazakstan, fossil mammals that encompass the Paleogene-Neogene boundary occur at three stratigraphic levels. The lowest level is in the lower Kyzylbulak Formation and produces Brontotheriidae and the hyracodontidArdynia and is tentatively assigned a late Eocene (Ergilian) age. The lower part of the overlying Aktau Formation produces fossils of the giant rhinocerosParaceratherium and is tentatively assigned a late Oligocene (Tabenbulukian) age. The upper part of the Aktau Formation yields a fossil mammal assemblage that includesGomphotherium,Stephanocemas, Brachypotherium andLagomeryx. It is clearly of Miocene age, probably late early Miocene (late Burdigalian), a correlative of European Reference Level MN 5 and the late Shanwangian of China. The Paleogene-Neogene boundary at Aktau Mountain thus is in the Aktau Formation. 相似文献
10.