全文获取类型
收费全文 | 893篇 |
免费 | 65篇 |
出版年
2023年 | 7篇 |
2022年 | 15篇 |
2021年 | 41篇 |
2020年 | 24篇 |
2019年 | 21篇 |
2018年 | 32篇 |
2017年 | 30篇 |
2016年 | 40篇 |
2015年 | 68篇 |
2014年 | 65篇 |
2013年 | 62篇 |
2012年 | 72篇 |
2011年 | 51篇 |
2010年 | 44篇 |
2009年 | 24篇 |
2008年 | 48篇 |
2007年 | 47篇 |
2006年 | 34篇 |
2005年 | 31篇 |
2004年 | 33篇 |
2003年 | 25篇 |
2002年 | 32篇 |
2001年 | 13篇 |
2000年 | 20篇 |
1999年 | 17篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1973年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有958条查询结果,搜索用时 15 毫秒
81.
The spatial and temporal variation of macroinvertebrate assemblages was studied in two Portuguese commercial rice agroecosystems
under the effect of field management involving the application of pesticides and fertilizers. A faunal succession of organisms
was observed on both fields. Grazers were the first to colonize the paddies after a dry period when pesticides were applied,
followed by development into nymphs and by an increase in the abundance of the species after the application of fertilizers.
At the end of the season when no pesticides or fertilizers were applied, the communities changed with the presence of adult
predators as a result of an increase in prey. Insecticide application revealed specific taxa increase due to the lack of competition
with the target organism. Macroinvertebrates tended to prefer infested field margins with aquatic, submerged vegetation, revealing
a spatial distribution along the paddies. Two different sampling devices were used and proved necessary in documenting the
macroinvertebrate communities (grab for benthic and hand-net for pelagic organisms). 相似文献
82.
Martins Renato T. Brito Janaina Dias-Silva Karina Leal Ceclia G. Leito Rafael P. Oliveira Vivian C. Oliveira-Jnior Jos M. B. de Paula Felipe R. Roque Fabio O. Hamada Neusa Juen Leandro Nessimian Jorge L. Pompeu Paulo S. Hughes Robert M. 《Hydrobiologia》2022,849(10):2281-2298
Hydrobiologia - Stream degradation in Amazonia is outpacing our ability to effectively monitor it for three key reasons: (1) Many changes are cumulative and occur gradually; (2) Scientists have... 相似文献
83.
Martins Renato Tavares de Freitas Silva Rafael Augusto Pinheiro Pinto Valria Arajo Braule Medeiros Adriana Oliveira Brito Laisa Hamada Neusa 《Hydrobiologia》2022,849(16):3531-3544
Hydrobiologia - We used experimental chambers to evaluate the effect of the temperature increasing and microbial conditioning degree on the survival and leaf consumption of two plant species... 相似文献
84.
Bernardes-Engemann Andréa Reis Almeida Marcos de Abreu Bison Ividy Rabello Vanessa Brito de Souza Ramos Mariana Lucy Mesquita Pereira Sandro Antonio Almeida-Paes Rodrigo de Lima Brasil Arthur Willian Zancopé-Oliveira Rosely Maria 《Mycopathologia》2022,187(4):375-384
Mycopathologia - Feline sporotrichosis has emerged as an important public health issue in some countries, especially Brazil. Currently, zoonotic transmission of Sporothrix brasiliensis by domestic... 相似文献
85.
Francinaldo Soares Silva Jefferson Mesquita Brito Benedita Maria Costa Neta Shelre Emile Pereira Duarte Lobo 《Memórias do Instituto Oswaldo Cruz》2015,110(6):801-803
Hoover Pugedo light traps were modified for use with green and blue-light-emitting
diodes to trap phlebotomine sandflies in northeastern Brazil. A total of 2,267
specimens belonging to eight genera and 15 species were sampled. The predominant
species were Nyssomyia whitmani(34.41%) and Micropygomyia
echinatopharynx(17.25%).The green LED trap prevailed over the blue and
control lights; however, no statistically significant difference could be detected
among the three light sources. Even without statistical significance, we suggest
using LEDs as an attractant for the capture of sandflies because of several
advantages over the conventional method with incandescent lamps. 相似文献
86.
87.
88.
Clare Edwards John Canfield Neil Copes Andres Brito Muhammad Rehan David Lipps Jessica Brunquell Sandy D Westerheide Patrick C Bradshaw 《BMC genetics》2015,16(1)
Background
Little is known about the role of amino acids in cellular signaling pathways, especially as it pertains to pathways that regulate the rate of aging. However, it has been shown that methionine or tryptophan restriction extends lifespan in higher eukaryotes and increased proline or tryptophan levels increase longevity in C. elegans. In addition, leucine strongly activates the TOR signaling pathway, which when inhibited increases lifespan.Results
Therefore each of the 20 proteogenic amino acids was individually supplemented to C. elegans and the effects on lifespan were determined. All amino acids except phenylalanine and aspartate extended lifespan at least to a small extent at one or more of the 3 concentrations tested with serine and proline showing the largest effects. 11 of the amino acids were less potent at higher doses, while 5 even decreased lifespan. Serine, proline, or histidine-mediated lifespan extension was greatly inhibited in eat-2 worms, a model of dietary restriction, in daf-16/FOXO, sir-2.1, rsks-1 (ribosomal S6 kinase), gcn-2, and aak-2 (AMPK) longevity pathway mutants, and in bec-1 autophagy-defective knockdown worms. 8 of 10 longevity-promoting amino acids tested activated a SKN-1/Nrf2 reporter strain, while serine and histidine were the only amino acids from those to activate a hypoxia-inducible factor (HIF-1) reporter strain. Thermotolerance was increased by proline or tryptophan supplementation, while tryptophan-mediated lifespan extension was independent of DAF-16/FOXO and SKN-1/Nrf2 signaling, but tryptophan and several related pyridine-containing compounds induced the mitochondrial unfolded protein response and an ER stress response. High glucose levels or mutations affecting electron transport chain (ETC) function inhibited amino acid-mediated lifespan extension suggesting that metabolism plays an important role. Providing many other cellular metabolites to C. elegans also increased longevity suggesting that anaplerosis of tricarboxylic acid (TCA) cycle substrates likely plays a role in lifespan extension.Conclusions
Supplementation of C. elegans with 18 of the 20 individual amino acids extended lifespan, but lifespan often decreased with increasing concentration suggesting hormesis. Lifespan extension appears to be caused by altered mitochondrial TCA cycle metabolism and respiratory substrate utilization resulting in the activation of the DAF-16/FOXO and SKN-1/Nrf2 stress response pathways.Electronic supplementary material
The online version of this article (doi:10.1186/s12863-015-0167-2) contains supplementary material, which is available to authorized users. 相似文献89.
90.