全文获取类型
收费全文 | 3641篇 |
免费 | 242篇 |
专业分类
3883篇 |
出版年
2024年 | 1篇 |
2023年 | 19篇 |
2022年 | 47篇 |
2021年 | 85篇 |
2020年 | 55篇 |
2019年 | 68篇 |
2018年 | 100篇 |
2017年 | 66篇 |
2016年 | 125篇 |
2015年 | 186篇 |
2014年 | 203篇 |
2013年 | 288篇 |
2012年 | 325篇 |
2011年 | 288篇 |
2010年 | 187篇 |
2009年 | 166篇 |
2008年 | 270篇 |
2007年 | 230篇 |
2006年 | 230篇 |
2005年 | 216篇 |
2004年 | 169篇 |
2003年 | 176篇 |
2002年 | 138篇 |
2001年 | 32篇 |
2000年 | 18篇 |
1999年 | 22篇 |
1998年 | 30篇 |
1997年 | 23篇 |
1996年 | 23篇 |
1995年 | 17篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1973年 | 3篇 |
1972年 | 2篇 |
排序方式: 共有3883条查询结果,搜索用时 15 毫秒
91.
92.
Wang-Sattler R Blandin S Ning Y Blass C Dolo G Touré YT delle Torre A Lanzaro GC Steinmetz LM Kafatos FC Zheng L 《PloS one》2007,2(11):e1249
Background
Attempts over the last three decades to reconstruct the phylogenetic history of the Anopheles gambiae species complex have been important for developing better strategies to control malaria transmission.Methodology
We used fingerprint genotyping data from 414 field-collected female mosquitoes at 42 microsatellite loci to infer the evolutionary relationships of four species in the A. gambiae complex, the two major malaria vectors A. gambiae sensu stricto (A. gambiae s.s.) and A. arabiensis, as well as two minor vectors, A. merus and A. melas.Principal Findings
We identify six taxonomic units, including a clear separation of West and East Africa A. gambiae s.s. S molecular forms. We show that the phylogenetic relationships vary widely between different genomic regions, thus demonstrating the mosaic nature of the genome of these species. The two major malaria vectors are closely related and closer to A. merus than to A. melas at the genome-wide level, which is also true if only autosomes are considered. However, within the Xag inversion region of the X chromosome, the M and two S molecular forms are most similar to A. merus. Near the X centromere, outside the Xag region, the two S forms are highly dissimilar to the other taxa. Furthermore, our data suggest that the centromeric region of chromosome 3 is a strong discriminator between the major and minor malaria vectors.Conclusions
Although further studies are needed to elucidate the basis of the phylogenetic variation among the different regions of the genome, the preponderance of sympatric admixtures among taxa strongly favor introgression of different genomic regions between species, rather than lineage sorting of ancestral polymorphism, as a possible mechanism. 相似文献93.
Slate Mandy L. Matallana-Mejia Nicolas Aromin Alessandra Callaway Ragan M. 《Biological invasions》2022,24(10):3109-3118
Biological Invasions - Temporally dynamic resource supplies may alter or lead to fluctuations in competitive outcomes. Resource pulses have been theorized to promote incursion by exotic species... 相似文献
94.
Castagneri Daniele Vacchiano Giorgio Hacket-Pain Andrew DeRose R. Justin Klein Tamir Bottero Alessandra 《Ecosystems》2022,25(1):30-43
Ecosystems - Drought will increasingly threaten forest ecosystems worldwide. Understanding how competition influences tree growth response to drought is essential for forest management aiming at... 相似文献
95.
Giorgio Perin Alessandra Bellan Andrea Bernardi Fabrizio Bezzo Tomas Morosinotto 《Physiologia plantarum》2019,166(1):380-391
The massive increase in carbon dioxide concentration in the atmosphere driven by human activities is causing huge negative consequences and new sustainable sources of energy, food and materials are highly needed. Algae are unicellular photosynthetic microorganisms that can provide a highly strategic contribution to this challenge as alternative source of biomass to complement crops cultivation. Algae industrial cultures are commonly limited by light availability, and biomass accumulation is strongly dependent on their photon‐to‐biomass conversion efficiency. Investigation of algae photosynthetic metabolism is thus strategic for the generation of more efficient strains with higher productivity. Algae are cultivated at industrial scale in conditions highly different from the natural niches they adapted to and strains development efforts must fully consider the seminal influence on productivity of regulatory mechanism of photosynthesis as well as of cultivation parameters like cells concentration, light distribution in the culture, mixing, nutrients and carbon dioxide availability. In this review we will focus in particular on how mathematical models can account for the complex influence of all environmental parameters and can be exploited for development of improved algae strains. 相似文献
96.
Scribano Vittorio Simakov Sergei K. Finocchiaro Claudio Correale Alessandra Scirè Salvatore 《Origins of life and evolution of the biosphere》2019,49(1-2):19-47
Origins of Life and Evolution of Biospheres - Pyrite and organic matter closely coexist in some hydrothermally-altered gabbroic xenoliths from the Hyblean Plateau, Sicily. The representative sample... 相似文献
97.
98.
Alessandra Santillo Sara Falvo Maria M. Di Fiore Federica Di Giacomo Russo Paolo Chieffi Alessandro Usiello Claudia Pinelli Gabriella Chieffi Baccari 《Journal of cellular biochemistry》2019,120(7):11044-11055
Excitatory amino acids (EAAs) are found present in the nervous and reproductive systems of animals. Numerous studies have demonstrated a regulatory role for Glutamate (Glu), d -aspartate ( d -Asp) and N-methyl- d -aspartate (NMDA) in the control of spermatogenesis. EAAs are able to stimulate the Glutamate receptors, including the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR). Here in, we assess expression of the main AMPAR subunits, GluA1 and GluA2/3, in the mouse testis and in spermatogonial GC-1 cells. The results showed that both GluA1 and GluA2/3 were localized in mouse testis prevalently in spermatogonia. The subunit GluA2/3 was more highly expressed compared with GluA1 in both the testis and the GC-1 cells. Subsequently, GC-1 cells were incubated with medium containing l -Glu, d -Glu, d -Asp or NMDA to determine GluA1 and GluA2/3 expressions. At 30 minutes and 2 hours of incubation, EAA-treated GC-1 cells showed significantly higher expression levels of both GluA1 and GluA2/3. Furthermore, p-extracellular signal-regulated kinase (ERK), p-Akt, proliferating cell nuclear antigen (PCNA), and Aurora B expressions were assayed in l -Glu-, d -Glu-, and NMDA-treated GC-1 cells. At 30 minutes and 2 hours of incubation, treated GC-1 cells showed significantly higher expression levels of p-ERK and p-Akt. A consequent increase of PCNA and Aurora B expressions was induced by l -Glu and NMDA, but not by d -Glu. Our study demonstrates a direct effect of the EAAs on spermatogonial activity. In addition, the increased protein expression levels of GluA1 and GluA2/3 in EAA-treated GC-1 cells suggest that EAAs could activate ERK and Akt pathways through the AMPAR. Finally, the increased PCNA and Aurora B levels may imply an enhanced proliferative activity. 相似文献
99.
100.