全文获取类型
收费全文 | 942篇 |
免费 | 67篇 |
专业分类
1009篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 17篇 |
2020年 | 11篇 |
2019年 | 15篇 |
2018年 | 19篇 |
2017年 | 20篇 |
2016年 | 21篇 |
2015年 | 54篇 |
2014年 | 43篇 |
2013年 | 91篇 |
2012年 | 101篇 |
2011年 | 82篇 |
2010年 | 64篇 |
2009年 | 40篇 |
2008年 | 57篇 |
2007年 | 62篇 |
2006年 | 56篇 |
2005年 | 57篇 |
2004年 | 58篇 |
2003年 | 41篇 |
2002年 | 22篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1009条查询结果,搜索用时 15 毫秒
961.
Lucilla Baldassarri Annalisa Pantosti Alfredo Caprioli Paola Mastrantonio Gianfranco Donelli 《FEMS microbiology letters》1989,60(1):1-4
The low heat resistance (D100 = 0.554 min, z = 13.4 degrees C) of dormant lysozyme-sensitized spores of Bacillus sphaericus 9602 was correlated with a low protoplast wet density (1.305 g/ml) equivalent to a high protoplast water content (61.0%, wet weight basis). These values for these unusual spores were consistent with those correlated previously in 28 spore types of seven other species. 相似文献
962.
Saverio Perri Matteo Detto Amilcare Porporato Annalisa Molini 《Global Ecology and Biogeography》2023,32(9):1561-1574
Aim
Mangrove canopy height is a key metric to assess tidal forests' resilience in the face of climate change. In terrestrial forests, tree height is primarily determined by water availability, plant hydraulic design, and disturbance regime. However, the role of water stress remains elusive in tidal environments, where saturated soils are prevalent, and salinity can substantially affect the soil water potential.Location
Global.Time Period
The canopy height dataset provides a global snapshot of the maximum mangrove height geographical distribution for the year 2000. Climate and environmental variables extend over the period 1970–2018.Major Taxa Studied
Mangroves.Methods
We use global observations of maximum canopy height, species richness, air temperature, and seawater salinity—a proxy of soil water salt concentration—to explore the causal link between salinity and mangrove stature.Results
Our findings suggest that salt stress limits mangrove height. High salinity favours more salt-tolerant species, narrowing the spectrum of viable traits. Highly salt-tolerant mangroves have evolved to cope with high salt concentrations in the soil, but this adaptation comes at a cost. They typically have lower rates of photosynthesis and growth, resulting in reduced productivity and smaller stature compared to more salt-sensitive mangrove species. This suggests a causal link between salinity, biodiversity, and tree height, where high salinity selects for more salt-tolerant species that tend to be less productive and shorter.Conclusions
We hypothesize that the salinity-induced limit to mangrove canopy height is the direct result of a reduction of primary productivity, an increment in the risk of xylem cavitation, and an indirect consequence of the decrease in biodiversity. As sea-level rise enhances coastal salinisation, failure to account for these effects can lead to incorrect estimates of future carbon stocks in Tropical coastal ecosystems and endanger preservation efforts. 相似文献963.
964.
965.
Laura Cremonesi Silvia Cainarca Annalisa Rossi Rita Padoan Maurizio Ferrari 《Human genetics》1996,98(1):119-121
Search for mutations in a cystic fibrosis patient, compound heterozygous for 1717–1G→A and another uncharacterized molecular
defect, revealed the presence of a de novo R1066H mutation on the affected chromosome of paternal origin. Three additional
rare mutations (R1066C, R1066S and R1066L), occurring at the CpG dinucleotide at position 3328–3329 of the cystic fibrosis
transmembrane conductance regulator gene, have so far been reported. The identification of a R1066H de novo mutation further
suggests that this dinucleotide may constitute a mutational hotspot.
Received: 10 November 1995 / Revised: 18 January 1996 相似文献
966.
The relationship between the synthesis of acidic nuclear proteins, phosphoproteins, RNA and chromatin ultrastructural pattern was studied in regenerating rat hepatocytes after partial hepatectomy. α-Amanitin induced, as early as 30 min after injection, a reduction of RNA synthesis to about 50% of the control level; the degree of inhibition had remained the same at 2 h after poisoning. No change was detected either in acidic nuclear protein synthesis or in phosphorylation for the whole time examined. The DNA-containing structures, demonstrated by the Gautier staining procedure, were in a dispersed pattern either in untreated regenerating hepatocytes or 30 min after α-amanitin administration to rats; but they did appear in a condensed form 1 h and more especially 2 h after toxin injection. In untreated regenerating hepatocytes, the regressive EDTA staining method for RNP revealed a large quantity of perichromatin fibrils which remained unchanged 30 min after α-amanitin treatment and were diminished at 1 h and strongly reduced 2 h thereafter.Cycloheximide treatment promptly reduced the synthesis of nuclear acidic proteins while leaving unchanged the synthesis of RNA; the quantity of perichromatin fibrils and the loosened appearance of DNA-containing structures were the same as in the control rat nuclei.Our results showed that the ultrastructural pattern of chromatin was not directly related either to the synthesis of RNA or to acidic nuclear proteins or to the phosphorylation of phosphoproteins; on the contrary, a strict relationship with the quantity of perichromatin fibrils was demonstrated. The possible interaction of perichromatin fibrils with other chromatin components was discussed as a possible regulatory mechanism of chromatin pattern. 相似文献
967.
968.
Federica Manca Stefania Puce Annalisa Caragnano Davide Maggioni Daniela Pica Davide Seveso Paolo Galli Simone Montano 《Zoologica scripta》2019,48(3):399-410
Hydrozoans of the genus Zanclea have been acknowledged only recently as a fundamental component of the highly diverse fauna associated with reef‐building scleractinian corals. Although widely distributed in coral reefs and demonstrated to be important in protecting corals from predation and diseases, the biodiversity of these hydrozoans remains enigmatic due to the paucity of available morphological characters, incomplete morphological characterisations and the possible existence of cryptic species. Recently, molecular techniques have revealed the existence of multiple hidden genetic lineages not yet supported by diagnostic morphological characters. In this work, we further explore the morpho‐diversity of three genetic lineages, namely Zanclea associated with the coral genera Goniastrea (clade I), Porites (clade II) and Pavona (clade VI). Aside from providing a complete classical characterisation of the polyp and medusa stage of each clade, we searched for new potential taxonomic indicators either on symbiotic hydroids or on host corals. On the hydroids, statistical analyses on almost 7,000 nematocyst capsules revealed a significant difference in terms of nematocyst size among the three Zanclea clades investigated. On each host coral genus, we identified peculiar skeletal modifications related to the presence of Zanclea symbionts. Lastly, we discussed the potential diagnostic value of these footprints in the characterisation of Zanclea–scleractinian associations. 相似文献
969.
970.