全文获取类型
收费全文 | 6770篇 |
免费 | 469篇 |
国内免费 | 4篇 |
出版年
2023年 | 58篇 |
2022年 | 118篇 |
2021年 | 211篇 |
2020年 | 126篇 |
2019年 | 146篇 |
2018年 | 212篇 |
2017年 | 165篇 |
2016年 | 307篇 |
2015年 | 434篇 |
2014年 | 443篇 |
2013年 | 577篇 |
2012年 | 666篇 |
2011年 | 554篇 |
2010年 | 317篇 |
2009年 | 260篇 |
2008年 | 390篇 |
2007年 | 404篇 |
2006年 | 321篇 |
2005年 | 286篇 |
2004年 | 252篇 |
2003年 | 210篇 |
2002年 | 194篇 |
2001年 | 50篇 |
2000年 | 36篇 |
1999年 | 42篇 |
1998年 | 37篇 |
1997年 | 30篇 |
1996年 | 29篇 |
1995年 | 29篇 |
1994年 | 25篇 |
1993年 | 28篇 |
1992年 | 25篇 |
1991年 | 16篇 |
1990年 | 12篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 19篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1981年 | 9篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1974年 | 14篇 |
1971年 | 6篇 |
1964年 | 6篇 |
1952年 | 4篇 |
排序方式: 共有7243条查询结果,搜索用时 171 毫秒
991.
992.
Thaís P. Mello Ana Carolina Aor Diego S. Gonçalves Sergio H. Seabra Marta H. Branquinha 《Biofouling》2016,32(7):737-749
Reported herein is the ability of Scedosporium apiospermum, S. aurantiacum, S. minutisporum and Lomentospora prolificans conidia to adhere, differentiate into hyphae and form biofilms on both polystyrene and lung epithelial cells. To different degrees, all of the fungi adhered to polystyrene after 4 h, with a predominance of those with germinated conidia. Prolonged fungi–polystyrene contact resulted in the formation of a monolayer of intertwined mycelia, which was identified as a typical biofilm structure due to the presence of a viable mycelial biomass, extracellular matrix and enhanced antifungal resistance. Ultrastructural details were revealed by SEM and CLSM, showing the dense compaction of the mycelial biomass and the presence of channels within the organized biofilm. A similar biofilm structure was observed following the co-culture of each fungus with A549 cells, revealing a mycelial trap covering all of the lung epithelial monolayer. Collectively, these results highlight the potential for biofilm formation by these clinically relevant fungal pathogens. 相似文献
993.
Nívia Carolina Nogueira-Paiva Paula Melo de Abreu Vieira Larissa Maris Rezende Oliveri Kátia da Silva Fonseca Gwenaelle Pound-Lana Maykon Tavares de Oliveira Marta de Lana Vanja Maria Veloso Alexandre Barbosa Reis Washington Luiz Tafuri Cláudia Martins Carneiro 《PloS one》2015,10(9)
The present study aims at establishing whether the diversity in pathogenesis within a genetically diverse host population infected with a single polyclonal strain of Trypanosoma cruzi is due to selection of specific subpopulations within the strain. For this purpose we infected Swiss mice, a genetically diverse population, with the polyclonal strain of Trypanosoma cruzi Berenice-78 and characterized via LSSP-PCR the kinetoplast DNA of subpopulations isolated from blood samples collected from the animals at various times after inoculation (3, 6 and 12 months after inoculation). We examined the biological behavior of the isolates in acellular medium and in vitro profiles of infectivity in Vero cell medium. We compared the characteristics of the isolates with the inoculating strain and with another strain, Berenice 62, isolated from the same patient 16 years earlier. We found that one of the isolates had intermediate behavior in comparison with Berenice-78 and Berenice-62 and a significantly different genetic profile by LSSP-PCR in comparison with the inoculating strain. We hereby demonstrate that genetically distinct Trypanosoma cruzi isolates may be obtained upon experimental murine infection with a single polyclonal Trypanosoma cruzi strain. 相似文献
994.
995.
996.
Vera Djordjilović Monica Chiogna M. Sofia Massa Chiara Romualdi 《Biometrical journal. Biometrische Zeitschrift》2015,57(5):852-866
Current demand for understanding the behavior of groups of related genes, combined with the greater availability of data, has led to an increased focus on statistical methods in gene set analysis. In this paper, we aim to perform a critical appraisal of the methodology based on graphical models developed in Massa et al. ( 2010 ) that uses pathway signaling networks as a starting point to develop statistically sound procedures for gene set analysis. We pay attention to the potential of the methodology with respect to the organizational aspects of dealing with such complex but highly informative starting structures, that is pathways. We focus on three themes: the translation of a biological pathway into a graph suitable for modeling, the role of shrinkage when more genes than samples are obtained, the evaluation of respondence of the statistical models to the biological expectations. To study the impact of shrinkage, two simulation studies will be run. To evaluate the biological expectation we will use data from a network with known behavior that offer the possibility of carrying out a realistic check of respondence of the model to changes in the experimental conditions. 相似文献
997.
998.
Carolina David Wiener Karen Jansen Gabriele Ghisleni Manuella Pinto Kaster Luciano Dias de Mattos Souza Diogo Rizzato Lara Luiz Valmor Portela Ricardo Azevedo da Silva Jean Pierre Oses 《Neurochemical research》2013,38(7):1394-1398
Several biological factors have been recently related with major depression and bipolar disorder. The aim of our paper was to investigate the peripheral levels of the protein neuronal specific enolase (NSE), a putative marker of neuronal damage, comparing patients with major depressive disorder and bipolar disorder to control subjects. This is a case–control study nested in a cross-sectional population-based survey. Psychopathology screen was performed using the Mini-International Neuropsychiatric Interview 5.0 and blood samples were collected from 108 young adults. Three groups were selected, 36 healthy controls, 36 subjects with major depression disorder and 36 subjects with bipolar disorder. Serum levels of NSE significantly decreased (p = 0.002) in major depression disorder (2.19 ± 1.78 ng/mL) and bipolar disorder subjects (2.53 ± 2.61 ng/mL) compared to the control group (3.55 ± 2.19 ng/mL). In conclusion, peripheral neuronal specific enolase may be a useful marker drug-naïve major depression disorder and bipolar disorder, but its pathophysiological significance and response to treatment should be further investigated. 相似文献
999.
Nicéia Spanholi Calgaroto Gustavo Roberto Thomé Pauline da Costa Jucimara Baldissareli Fátima Abdala Hussein Roberta Schmatz Maribel A. Rubin Cristiane Signor Daniela Aymone Ribeiro Fabiano Barbosa Carvalho Lizielle Souza de Oliveira Luciane Belmonte Pereira Vera Maria Morsch Maria Rosa Chitolina Schetinger 《Cell biochemistry and function》2014,32(6):502-510
Diabetes is associated with long‐term complications in the brain and reduced cognitive ability. Vitamin D3 (VD3) appears to be involved in the amelioration of hyperglycaemia in streptozotocin (STZ)‐induced diabetic rats. Our aim was to analyse the potential of VD3 in avoiding brain damage through evaluation of acetylcholinesterase (AChE), Na+K+‐adenosine triphosphatase (ATPase) and delta aminolevulinate dehydratase (δ‐ALA‐D) activities and thiobarbituric acid reactive substance (TBARS) levels from cerebral cortex, as well as memory in STZ‐induced diabetic rats. Animals were divided into eight groups (n = 5): control/saline, control/metformin (Metf), control/VD3, control/Metf + VD3, diabetic/saline, diabetic/Metf, diabetic/VD3 and diabetic/Metf + VD3. Thirty days after treatment, animals were submitted to contextual fear‐conditioning and open‐field behavioural tests, after which they were sacrificed and the cerebral cortex was dissected. Our results demonstrate a significant memory deficit, an increase in AChE activity and TBARS levels and a decrease in δ‐ALA‐D and Na+K+‐ATPase activities in diabetic rats when compared with the controls. Treatment of diabetic rats with Metf and VD3 prevented the increase in AChE activity when compared with the diabetic/saline group. In treated diabetic rats, the decrease in Na+K+‐ATPase was reverted when compared with non‐treated rats, but the increase in δ‐ALA‐D activity was not. VD3 prevented diabetes‐induced TBARS level and improved memory. Our results show that VD3 can avoid cognitive deficit through prevention of changes in important enzymes such as Na+K+‐ATPase and AChE in cerebral cortex in type 1 diabetic rats. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
1000.