全文获取类型
收费全文 | 2868篇 |
免费 | 168篇 |
专业分类
3036篇 |
出版年
2023年 | 25篇 |
2022年 | 58篇 |
2021年 | 111篇 |
2020年 | 60篇 |
2019年 | 77篇 |
2018年 | 90篇 |
2017年 | 90篇 |
2016年 | 126篇 |
2015年 | 178篇 |
2014年 | 201篇 |
2013年 | 237篇 |
2012年 | 222篇 |
2011年 | 215篇 |
2010年 | 148篇 |
2009年 | 108篇 |
2008年 | 141篇 |
2007年 | 117篇 |
2006年 | 112篇 |
2005年 | 90篇 |
2004年 | 104篇 |
2003年 | 80篇 |
2002年 | 80篇 |
2001年 | 61篇 |
2000年 | 39篇 |
1999年 | 37篇 |
1998年 | 20篇 |
1997年 | 15篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 18篇 |
1991年 | 13篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1975年 | 3篇 |
1971年 | 3篇 |
1970年 | 4篇 |
1969年 | 9篇 |
1968年 | 5篇 |
1965年 | 4篇 |
排序方式: 共有3036条查询结果,搜索用时 0 毫秒
61.
62.
Partial sequencing and mapping of clones from two maize cDNA libraries 总被引:11,自引:0,他引:11
63.
Gupta Achla Gullapalli Srinivas Pan Hui Ramos-Ortolaza Dinah L. Hayward Michael D. Low Malcom J. Pintar John E. Devi Lakshmi A. Gomes Ivone 《Cellular and molecular neurobiology》2021,41(5):1103-1118
Cellular and Molecular Neurobiology - Activation of μ, δ, and κ opioid receptors by endogenous opioid peptides leads to the regulation of many emotional and physiological responses.... 相似文献
64.
Daniel Ruivo Marques Paula Castilho Ana Allen Gomes Anabela Pereira 《Chronobiology international》2019,36(4):541-547
It is well established in the literature that morning-type individuals present better health indicators than evening-types. Mindfulness is considered an adaptive self-regulation skill associated with well-being and physical and mental health. However, there is scarce studies that relate chronotype and mindfulness. Thus, in this research, our aim was to study the relationship between chronotype and mindfulness-related variables. For this purpose, a sample composed of 483 participants from the community was recruited through an online survey and invited to fill out the Five Facet Mindfulness Questionnaire, the Self-Compassion Scale, and the Composite Morningness Scale. Regarding mindfulness measure, the results indicated that morning-types presented higher levels of “acting with awareness” than intermediate and evening-types. Additionally, as to self-compassion measure, morning-types presented higher levels of “mindfulness” and “overall self-compassion” than intermediate and evening-types. The remaining associations examined were not statistically significant. In sum, the morning-types showed higher scores in some of the mindfulness and self-compassion scales which seem to suggest that this morningness tendency may function as protective factor concerning eventual disorders´ development. Nonetheless, more systematic studies are needed to better understand this association and subsequently foster changes for psychological intervention. 相似文献
65.
Disturbances, elevation, topography and spatial proximity drive vegetation patterns along an altitudinal gradient of a top biodiversity hotspot 总被引:1,自引:0,他引:1
Pedro V. Eisenlohr Luciana F. Alves Luís Carlos Bernacci Maíra C. G. Padgurschi Roseli B. Torres Eduardo M. B. Prata Flavio Antonio M. dos Santos Marco Antônio Assis Eliana Ramos André Luís C. Rochelle Fernando R. Martins Mariana C. R. Campos Fernando Pedroni Maryland Sanchez Larissa S. Pereira Simone A. Vieira José Ataliba M. A. Gomes Jorge Y. Tamashiro Marcos A. S. Scaranello Cora J. Caron Carlos Alfredo Joly 《Biodiversity and Conservation》2013,22(12):2767-2783
The correlation between vegetation patterns (species distribution and richness) and altitudinal variation has been widely reported for tropical forests, thereby providing theoretical basis for biodiversity conservation. However, this relationship may have been oversimplified, as many other factors may influence vegetation patterns, such as disturbances, topography and geographic distance. Considering these other factors, our primary question was: is there a vegetation pattern associated with substantial altitudinal variation (10–1,093 m a.s.l.) in the Atlantic Rainforest—a top hotspot for biodiversity conservation—and, if so, what are the main factors driving this pattern? We addressed this question by sampling 11 1-ha plots, applying multivariate methods, correlations and variance partitioning. The Restinga (forest on sandbanks along the coastal plains of Brazil) and a lowland area that was selectively logged 40 years ago were floristically isolated from the other plots. The maximum species richness (>200 spp. per hectare) occurred at approximately 350 m a.s.l. (submontane forest). Gaps, multiple stemmed trees, average elevation and the standard deviation of the slope significantly affected the vegetation pattern. Spatial proximity also influenced the vegetation pattern as a structuring environmental variable or via dispersal constraints. Our results clarify, for the first time, the key variables that drive species distribution and richness across a large altitudinal range within the Atlantic Rainforest. 相似文献
66.
Rachel Montesinos Hélio Ricardo da Silva André Luiz Gomes de Carvalho 《Biotropica》2012,44(4):506-511
Darwin and Wallace, in the mid‐nineteenth century, were the first to document examples of natural selection acting on island dwellers. A century later a pattern of morphological differences among organisms on islands was coined the ‘island rule’, which states that on islands species with small individuals tend toward gigantism and large individuals tend toward dwarfism. Selective pressures such as limited resources and increased intraspecific competition modulate the size of organisms in these environments. Of the several works that have tested vertebrates for adherence to the island rule only two have addressed amphibians. This work is the third record of body size variation of island amphibian populations, and the first for the Southern Hemisphere. The islands investigated were once continuous with mainland, and now are isolated as a result of sea level fluctuations that took place in the Pleistocene and Holocene. This study compared morphometric variation in populations of Rhinella ornata (Bufonidae) occurring on three islands of the Costa Verde to populations on five continental areas in Rio de Janeiro, Brazil. We measured 18 morphometric variables of 177 individuals. There was a shift toward smaller body size (dwarfism) in two of the three island populations studied. We attribute this general pattern to geographic factors, verifying the expression of the island rule in tropical frogs populations (insular dwarfism) operating inversely in relation to those of temperate environments (island gigantism). 相似文献
67.
68.
Regulation of AMPA Receptor Activity, Synaptic Targeting and Recycling: Role in Synaptic Plasticity 总被引:7,自引:0,他引:7
The alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors for the neurotransmitter glutamate are oligomeric structures responsible for most fast excitatory responses in the central nervous system. The activity of AMPA receptors can be directly regulated by protein phosphorylation, which may also affect the interaction with intracellular proteins and, consequently, their recycling and localization to defined postsynaptic sites. This review focuses on recent advances in understanding the dynamic regulation of AMPA receptors, on a short- and long-term basis, and its implications in synaptic plasticity. 相似文献
69.
70.
Three hundred and thirty nine lactic bacteria strains isolated from food samples were screened for antimicrobial activity.
Only one strain isolated from meat pie and identified as Enterococcus faecium produced a bacteriocin-like inhibitory substance (BLIS) showing activity against Enterococcus, Leuconostoc, Lactobacillus, Listeria, Corynebacterium and Staphylococcus aureus. The BLIS produced was resistant to acid and alkali treatment and 121oC for 15 min. The addition of BLIS in BHI contaminated
with Listeria monocytogenes decreased the contamination in 4.8 log cycles in 24 h. The inhibition of listeria was also obtained in milk. Forty multiresistant
enterococci strains were inhibited in the well-diffusion test. Two vancomycin resistant strains tested in liquid with BLIS
were also inhibited. The BLIS producer showed no pathogenicity marker. 相似文献