全文获取类型
收费全文 | 503篇 |
免费 | 18篇 |
专业分类
521篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 5篇 |
2018年 | 9篇 |
2017年 | 10篇 |
2016年 | 16篇 |
2015年 | 30篇 |
2014年 | 45篇 |
2013年 | 34篇 |
2012年 | 37篇 |
2011年 | 29篇 |
2010年 | 21篇 |
2009年 | 20篇 |
2008年 | 23篇 |
2007年 | 35篇 |
2006年 | 32篇 |
2005年 | 23篇 |
2004年 | 21篇 |
2003年 | 21篇 |
2002年 | 22篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有521条查询结果,搜索用时 15 毫秒
31.
Gabriel Costa Serr?o de Araújo Natália Teixeira Mour?o Igor Natário Pinheiro Analúcia Rampazzo Xavier Vinicius Schott Gameiro 《PloS one》2015,10(10)
Background
Gunshot wounds require surgeons to decide whether to remove or leave bullet fragments in the body. Surgeons also decide how to follow up with patients who have lead fragments retained in their body. Current literature recommends to remove only intra-articular fragments without the need for a follow-up for patients with the metal retained. Therefore, this study investigates chronic lead toxicity for gunshot wounds.Methods
The study was performed in the metropolitan area of Rio de Janeiro/Brazil, between 2013 and 2015. It was a case-control study that included 45 victims of gunshot lesions with metallic fragments retained for more than 6 months. The 45 controls were matched for gender, age, and race. We compared the lead blood levels and frequency of symptoms.Results
The control group had average blood lead levels of 2.17 μg/dL (95% Confidence Interval [CI]; 1.71–2.63) and median 2.1 μg/dL. The case group had average values of 9.01 μg/dL (CI; 6.07–11.96) and median values of 6.5 μg/dL with p-values < = 0.001. The case group reported the following more frequently: irritancy, bad mood, headache, memory losses, daylight drowsiness, myalgia, weakness, abdominal pain, joint pain, trembling, tingling limbs. There was statistical significance for the differences of symptoms frequencies and for odds ratio between groups.Conclusions
Although the mean lead levels found were lower than the current laboratory references, low levels have been associated with both rising morbidity and mortality. The WHO stated: “There is no known level of lead exposure that is considered safe”. In conclusion, this work showed that bullets retained in the body are not innocuous. There are impacts in the blood lead levels and symptoms related to it, even with few fragments, extra-articular located or existing with low blood lead levels. 相似文献32.
Thalita S. Camargos Frank Bosmans Solange C. Rego Caroline B. F. Mour?o Elisabeth F. Schwartz 《PloS one》2015,10(6)
We identified Tf2, the first β-scorpion toxin from the venom of the Brazilian scorpion Tityus fasciolatus. Tf2 is identical to Tb2-II found in Tityus bahiensis. We found that Tf2 selectively activates human (h)Nav1.3, a neuronal voltage-gated sodium (Nav) subtype implicated in epilepsy and nociception. Tf2 shifts hNav1.3 activation voltage to more negative values, thereby opening the channel at resting membrane potentials. Seven other tested mammalian Nav channels (Nav1.1-1.2; Nav1.4-1.8) expressed in Xenopus oocytes are insensitive upon application of 1 μM Tf2. Therefore, the identification of Tf2 represents a unique addition to the repertoire of animal toxins that can be used to investigate Nav channel function. 相似文献
33.
The physicochemical properties of cellular environments with a high macromolecular content have been systematically characterized to explain differences observed in the diffusion coefficients, kinetics parameters, and thermodynamic properties of proteins inside and outside of cells. However, much less attention has been given to the effects of macromolecular crowding on cell physiology. Here, we review recent findings that shed some light on the role of crowding in various cellular processes, such as reduction of biochemical activities, structural reorganization of the cytoplasm, cytoplasm fluidity, and cellular dormancy. We conclude by presenting some unresolved problems that require the attention of biophysicists, biochemists, and cell physiologists. Although it is still underappreciated, macromolecular crowding plays a critical role in life as we know it. 相似文献
34.
Eduardo Vilanova Cristiano Coutinho Guilherme Maia Paulo A. S. Mourão 《Cell and tissue research》2010,340(3):523-531
Marine sponges (Porifera) display an ancestral type of cell-cell adhesion, based on carbohydrate-carbohydrate interaction.
The aim of the present work was to investigate further details of this adhesion by using, as a model, the in vitro aggregation
of dissociated sponge cells. Our results showed the participation of sulfated polysaccharides in this cell-cell interaction,
as based on the following observations: (1) a variety of sponge cells contained similar sulfated polysaccharides as surface-associated
molecules and as intracellular inclusions; (2) 35S-sulfate metabolic labeling of dissociated sponge cells revealed that the majority (two thirds) of the total sulfated polysaccharide
occurred as a cell-surface-associated molecule; (3) the aggregation process of dissociated sponge cells demanded the active
de novo synthesis of sulfated polysaccharides, which ceased as cell aggregation reached a plateau; (4) the typical well-organized
aggregates of sponge cells, known as primmorphs, contained three cell types showing sulfated polysaccharides on their cell
surface; (5) collagen fibrils were also produced by the primmorphs in order to fill the extracellular spaces of their inner
portion and the external layer surrounding their entire surface. Our data have thus clarified the relevance of sulfated polysaccharides
in this system of in vitro sponge cell aggregation. The molecular basis of this system has practical relevance, since the
culture of sponge cells is necessary for the production of molecules with biotechnological applications. 相似文献
35.
Luciane A. Faine Danielle M.H. Cavalcanti Martina Rudnicki Simone Ferderbar Sandra M.D. Macedo Heraldo P. Souza Sandra H.P. Farsky Lisardo Boscá Dulcineia Saes Parra Abdalla 《The Journal of nutritional biochemistry》2010,21(2):125-132
The vascular effects of nitrolinoleate (LNO2), an endogenous product of linoleic acid (LA) nitration by nitric oxide-derived species and a potential nitrosating agent, were investigated on rat endothelial-leukocyte interactions. Confocal microscopy analysis demonstrated that LNO2 was capable to deliver free radical nitric oxide (·NO) into cells, 5 min after its administration to cultured cells, with a peak of liberation at 30 min. THP-1 monocytes incubated with LNO2 for 5 min presented nitrosation of CD40, leading to its inactivation. Other anti-inflammatory actions of LNO2 were observed in vivo by intravital microscopy assays. LNO2 decreased the number of adhered leukocytes in postcapillary venules of the mesentery network. In addition to this, LNO2 reduced mRNA and protein expression of β2-integrin in circulating leukocytes, as well as VCAM-1 in endothelial cells isolated from postcapillary venules, confirming its antiadhesive effects on both cell types. Moreover, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, a nitric oxide scavenger, partially abolished the inhibitory action of LNO2 on leukocyte-endothelium interaction, suggesting that the antiadhesion effects of LNO2 involve a dual role in leukocyte adhesion, acting as a nitric oxide donor as well as through nitric oxide-independent mechanisms. In conclusion, LNO2 inhibited adhesion molecules expression and promoted ·NO inactivation of the CD40–CD40L system, both important processes of the inflammatory response. 相似文献
36.
37.
Camille E. Granada Marcos Strochein Luciano K. Vargas Manuela Bruxel Enilson Luiz Saccol de Sá Luciane M.P. Passaglia 《Genetics and molecular biology》2014,37(2):396-405
This work aimed to evaluate the symbiotic compatibility and nodulation efficiency of rhizobia isolated from Desmodium incanum, Lotus corniculatus, L. subbiflorus, L. uliginosus and L. glaber plants by cross-inoculation. Twelve reference strains and 21 native isolates of rhizobia were genetically analyzed by the BOX-PCR technique, which showed a high genetic diversity among the rhizobia studied. The isolates were also characterized based on their production of indolic compounds and siderophores, as well as on their tolerance to salinity. Fifteen of the 33 rhizobia analyzed were able to produce indolic compounds, whereas 13 produced siderophores. All the tested rhizobia were sensitive to high salinity, although some were able to grow in solutions of up to 2% NaCl. Most of the native rhizobia isolated from L. uliginosus were able to induce nodulation in all plant species studied. In a greenhouse experiment using both D. incanum and L. corniculatus plants, the rhizobia isolate UFRGS Lu2 promoted the greatest plant growth. The results demonstrate that there are native rhizobia in the soils of southern Brazil that have low host specificity and are able to induce nodulation and form active nodules in several plant species. 相似文献
38.
Alessandra Bertassoni Guilherme Mourão Rullian César Ribeiro Clarice Silva Cesário Juliana Paula de Oliveira Rita de Cassia Bianchi 《Studies on Neotropical Fauna and Environment》2017,52(1):68-74
This study analyzes a giant anteater’s (Myrmecophaga tridactyla) movement patterns and space use in São Paulo, Brazil. It is the first study to track a giant anteater with Iridium-GPS. The anteater traveled an average distance of 1326 m day–1 with an average speed of 1.04 m min–1. Home range by Kernel was 2.46 km2 while the core area was 0.75 km2, and estimates by Brownian bridge and minimum convex polygon were also provided. The anteater used shrub savanna, open savanna, and water habitats more than expected. Monitoring ended just after 10 days when the female giant anteater’s GPS was found on an illegal trail. 相似文献
39.
40.