全文获取类型
收费全文 | 7491篇 |
免费 | 524篇 |
国内免费 | 2篇 |
出版年
2023年 | 33篇 |
2022年 | 19篇 |
2021年 | 134篇 |
2020年 | 100篇 |
2019年 | 119篇 |
2018年 | 210篇 |
2017年 | 167篇 |
2016年 | 265篇 |
2015年 | 455篇 |
2014年 | 476篇 |
2013年 | 537篇 |
2012年 | 688篇 |
2011年 | 585篇 |
2010年 | 364篇 |
2009年 | 350篇 |
2008年 | 488篇 |
2007年 | 432篇 |
2006年 | 366篇 |
2005年 | 333篇 |
2004年 | 350篇 |
2003年 | 325篇 |
2002年 | 224篇 |
2001年 | 105篇 |
2000年 | 101篇 |
1999年 | 92篇 |
1998年 | 36篇 |
1997年 | 40篇 |
1996年 | 44篇 |
1995年 | 33篇 |
1994年 | 20篇 |
1993年 | 23篇 |
1992年 | 31篇 |
1991年 | 23篇 |
1990年 | 26篇 |
1989年 | 29篇 |
1988年 | 23篇 |
1987年 | 26篇 |
1986年 | 20篇 |
1985年 | 25篇 |
1984年 | 18篇 |
1983年 | 16篇 |
1982年 | 14篇 |
1981年 | 15篇 |
1980年 | 15篇 |
1975年 | 18篇 |
1974年 | 21篇 |
1973年 | 26篇 |
1972年 | 15篇 |
1971年 | 16篇 |
1970年 | 15篇 |
排序方式: 共有8017条查询结果,搜索用时 31 毫秒
1.
2.
3.
Allopatric isolation in glacial refugia has caused differentiation and speciation in many taxa globally. In this study, we investigated the nuclear and mitochondrial genetic differentiation of the long fingered bat, Myotis capaccinii during the ice ages in south-eastern Europe and Anatolia. The mitochondrial DNA (mtDNA) analyses indicated a suture zone similar to those recorded in other animal species, including bats, suggesting the association of more than one refugium with the region. Contrary to most of the other species where a suture zone was seen in Anatolia, for M. capaccinii the geographical location of the genetic break was in south-eastern Europe. This mitochondrial differentiation was not reflected in the nuclear microsatellites, however, suggesting that the lack of contact during the ice ages did not result in reproductive isolation. Hence taxonomically, the two mitochondrial clades cannot be treated as separate species. 相似文献
4.
Blanco Pablo J. Müller Lucas O. Watanabe Sansuke M. Feijóo Raúl A. 《Biomechanics and modeling in mechanobiology》2020,19(5):1663-1678
Biomechanics and Modeling in Mechanobiology - The goal of this work is to assess the impact of vascular anatomy definition degree in the predictions of blood flow models of the arterial network. To... 相似文献
5.
A N Dedenkov N T Ra?khlin I M Kvetno? E S Kurilets I P Balmasova 《Biulleten' eksperimental'no? biologii i meditsiny》1986,102(10):491-493
The ability of serotonin, melatonin and beta-endorphin synthesis by secreting granules of natural killer cells (NK cells) was established by immunohistochemical method. It was shown that cytotoxic effect of NK cells can be to a certain extent related to the presence of secreting granules. A possible direct contribution of NK cell-synthesized hormones to the natural killer antitumour effect is discussed. 相似文献
6.
Secretion of Recombinant Pediocin PA-1 by Bifidobacterium longum, Using the Signal Sequence for Bifidobacterial α-Amylase 下载免费PDF全文
Gi-Seong Moon Yu-Ryang Pyun Myeong Soo Park Geun Eog Ji Wang June Kim 《Applied microbiology》2005,71(9):5630-5632
A recombinant DNA, encoding the chimeric protein of the signal sequence for bifidobacterial α-amylase mature pediocin PA-1, was introduced into Bifidobacterium longum MG1. Biologically active pediocin PA-1 was successfully secreted from the strain and showed bactericidal activity against Listeria monocytogenes and the same molecular mass as native pediocin PA-1. 相似文献
7.
Francisco Del Pino Claudia Jara Luis Pino María Cristina Medina-Mu?oz Eduardo Alvarez Raúl Godoy-Herrera 《PloS one》2015,10(8)
We investigated the role of Drosophila larva olfactory system in identification of congeners and aliens. We discuss the importance of these activities in larva navigation across substrates, and the implications for allocation of space and food among species of similar ecologies. Wild type larvae of cosmopolitan D. melanogaster and endemic D. pavani, which cohabit the same breeding sites, used species-specific volatiles to identify conspecifics and aliens moving toward larvae of their species. D. gaucha larvae, a sibling species of D. pavani that is ecologically isolated from D. melanogaster, did not respond to melanogaster odor cues. Similar to D. pavani larvae, the navigation of pavani female x gaucha male hybrids was influenced by conspecific and alien odors, whereas gaucha female x pavani male hybrid larvae exhibited behavior similar to the D. gaucha parent. The two sibling species exhibited substantial evolutionary divergence in processing the odor inputs necessary to identify conspecifics. Orco (Or83b) mutant larvae of D. melanogaster, which exhibit a loss of sense of smell, did not distinguish conspecific from alien larvae, instead moving across the substrate. Syn
97CS and rut larvae of D. melanogaster, which are unable to learn but can smell, moved across the substrate as well. The Orco (Or83b), Syn
97CS and rut loci are necessary to orient navigation by D. melanogaster larvae. Individuals of the Trana strain of D. melanogaster did not respond to conspecific and alien larval volatiles and therefore navigated randomly across the substrate. By contrast, larvae of the Til-Til strain used larval volatiles to orient their movement. Natural populations of D. melanogaster may exhibit differences in identification of conspecific and alien larvae. Larval locomotion was not affected by the volatiles. 相似文献
8.
Advanced hepatic fibrosis therapy using drug-delivering nanoparticles is a relatively unexplored area. Angiotensin type 1 (AT1) receptor blockers such as losartan can be delivered to hepatic stellate cells (HSC), blocking their activation and thereby reducing fibrosis progression in the liver. In our study, we analyzed the possibility of utilizing drug-loaded vehicles such as hyaluronic acid (HA) micelles carrying losartan to attenuate HSC activation. Losartan, which exhibits inherent lipophilicity, was loaded into the hydrophobic core of HA micelles with a 19.5% drug loading efficiency. An advanced liver fibrosis model was developed using C3H/HeN mice subjected to 20 weeks of prolonged TAA/ethanol weight-adapted treatment. The cytocompatibility and cell uptake profile of losartan-HA micelles were studied in murine fibroblast cells (NIH3T3), human hepatic stellate cells (hHSC) and FL83B cells (hepatocyte cell line). The ability of these nanoparticles to attenuate HSC activation was studied in activated HSC cells based on alpha smooth muscle actin (α-sma) expression. Mice treated with oral losartan or losartan-HA micelles were analyzed for serum enzyme levels (ALT/AST, CK and LDH) and collagen deposition (hydroxyproline levels) in the liver. The accumulation of HA micelles was observed in fibrotic livers, which suggests increased delivery of losartan compared to normal livers and specific uptake by HSC. Active reduction of α-sma was observed in hHSC and the liver sections of losartan-HA micelle-treated mice. The serum enzyme levels and collagen deposition of losartan-HA micelle-treated mice was reduced significantly compared to the oral losartan group. Losartan-HA micelles demonstrated significant attenuation of hepatic fibrosis via an HSC-targeting mechanism in our in vitro and in vivo studies. These nanoparticles can be considered as an alternative therapy for liver fibrosis. 相似文献
9.
The purpose of this review is to provide an overview of the effects of adenovirus and influenza virus infections on obesity in various experimental models. We reviewed studies that were conducted within the past 10 years and were related to virus infection and obesity prevalence. Here, we discuss a different causal relationship between adenovirus and influenza infections with obesity. Adenovirus infection can cause obesity, whereas obesity can be a risk factor for increasing influenza virus infection and increases the risk of morbidity and mortality. The prevalence of obesity due to adenovirus infections may be due to an increase in glucose uptake and reduction in lipolysis caused by an increase in corticosterone secretion. Adenovirus infections may lead to increases in appetite by decreasing norepinephrine and leptin levels and also cause immune dysfunction. The relationship between obesity and influenza virus infection could be summarized by the following features: decreases in memory T-cell functionality and interferon (IFN)-α, IFN-β, and IFN-γ mRNA expression, increases in viral titer and infiltration, and impaired dendritic cell function in obese individuals. Moreover, leptin resistance may play an important role in increasing influenza virus infections in obese individuals. In conclusion, prevention of adenovirus infections could be a good approach for reducing obesity prevalence, and prevention of obesity could reduce influenza virus infections from the point of view of viral infections and obesity. 相似文献
10.