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91.
Sommer ME Farrens DL McDowell JH Weber LA Smith WC 《The Journal of biological chemistry》2007,282(35):25560-25568
In this study we investigate conformational changes in Loop V-VI of visual arrestin during binding to light-activated, phosphorylated rhodopsin (Rho*-P) using a combination of site-specific cysteine mutagenesis and intramolecular fluorescence quenching. Introduction of cysteines at positions in the N-domain at residues predicted to be in close proximity to Ile-72 in Loop V-VI of arrestin (i.e. Glu-148 and Lys-298) appear to form an intramolecular disulfide bond with I72C, significantly diminishing the binding of arrestin to Rho*-P. Using a fluorescence approach, we show that the steady-state emission from a monobromobimane fluorophore in Loop V-VI is quenched by tryptophan residues placed at 148 or 298. This quenching is relieved upon binding of arrestin to Rho*-P. These results suggest that arrestin Loop V-VI moves during binding to Rho*-P and that conformational flexibility of this loop is essential for arrestin to adopt a high affinity binding state. 相似文献
92.
Bruno JF Selig ER Casey KS Page CA Willis BL Harvell CD Sweatman H Melendy AM 《PLoS biology》2007,5(6):e124
Very little is known about how environmental changes such as increasing temperature affect disease dynamics in the ocean, especially at large spatial scales. We asked whether the frequency of warm temperature anomalies is positively related to the frequency of coral disease across 1,500 km of Australia's Great Barrier Reef. We used a new high-resolution satellite dataset of ocean temperature and 6 y of coral disease and coral cover data from annual surveys of 48 reefs to answer this question. We found a highly significant relationship between the frequencies of warm temperature anomalies and of white syndrome, an emergent disease, or potentially, a group of diseases, of Pacific reef-building corals. The effect of temperature was highly dependent on coral cover because white syndrome outbreaks followed warm years, but only on high (>50%) cover reefs, suggesting an important role of host density as a threshold for outbreaks. Our results indicate that the frequency of temperature anomalies, which is predicted to increase in most tropical oceans, can increase the susceptibility of corals to disease, leading to outbreaks where corals are abundant. 相似文献
93.
Hugh Dainer John Nelson Kathryn Brass Elizabeth Montcalm-Smith Richard Mahon 《Journal of applied physiology》2007,102(3):1099-1104
Disabled submarine (DISSUB) survivors will achieve inert gas tissue saturation within 24 h. Direct ascent to the surface when saturated carries a high risk of decompression sickness (DCS) and death, yet may be necessary during rescue or escape. O(2) has demonstrated benefits in decreasing morbidity and mortality resulting from DCS by enhancing inert gas elimination. Perfluorocarbons (PFCs) also mitigate the effects of DCS by decreasing bubble formation and increasing O(2) delivery. Our hypothesis is that combining O(2) prebreathing (OPB) and PFC administration will reduce the incidence of DCS and death following saturation in an established 20-kg swine model. Yorkshire swine (20 +/- 6.5 kg) were compressed to 5 atmospheres (ATA) in a dry chamber for 22 h before randomization into one of four groups: 1) air and saline, 2) OPB and saline, 3) OPB with PFC given at depth, 4) OPB with PFC given after surfacing. OPB animals received >90% O(2) for 9 min at depth. All animals were returned to the surface (1 ATA) without decompression stops. The incidence of severe DCS < 2 h after surfacing was 96%, 63%, 82%, and 29% for groups 1, 2, 3, and 4, respectively. The incidence of death was 88%, 41%, 54%, and 5% for groups 1, 2, 3, and 4, respectively. OPB combined with PFC administration after surfacing provided the greatest reduction in DCS morbidity and mortality in a saturation swine model. O(2)-related seizure activity before reaching surface did not negatively affect outcome, but further safety studies are warranted. 相似文献
94.
95.
Leigh‐Ann Woolley Hayley M. Geyle Brett P. Murphy Sarah M. Legge Russell Palmer Christopher R. Dickman John Augusteyn Sarah Comer Tim S. Doherty Charlie Eager Glenn Edwards Dan K.P. Harley Ian Leiper Peter J. McDonald Hugh W. McGregor Katherine E. Moseby Cecilia Myers John L. Read Joanna Riley Danielle Stokeld Jeff M. Turpin John C.Z. Woinarski 《Mammal Review》2019,49(4):354-368
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96.
Abstract A bacterium capable of growth from 59 to 72° C was isolated from geothermal soil collected from Mount Erebus, Ross Island, Antarctica. The isolate was enriched in medium containing thiosulphate and bicarbonate. Subsequently the organism was found also to be capable of heterotrophic growth and autotrophic growth in the presence of hydrogen and carbon dioxide. In a comparison with Bacillus schlegelii and Bacillus tusciae the isolate most closely resembled B. schlegelii . This conclusion was supported by the finding that B. schlegelii is also capable of autotrophic growth using thiosulphate. The new isolate had a characteristic subunit layer on the cell wall which is typical of B. schlegelii . 相似文献
97.
Lijuan Zhang Ramanaiah Mamillapalli Shutaro Habata Molly McAdow Hugh S. Taylor 《Journal of cellular and molecular medicine》2022,26(9):2566
Preterm birth is a major contributor to neonatal mortality and morbidity. Infection results in elevation of inflammation‐related cytokines followed by infiltration of immune cells into gestational tissue. CXCL12 levels are elevated in preterm birth indicating it may have a role in preterm labour (PTL); however, the pathophysiological correlations between CXCL12/CXCR4 signalling and premature labour are poorly understood. In this study, PTL was induced using lipopolysaccharide (LPS) in a murine model. LPS induced CXCL12 RNA and protein levels significantly and specifically in myometrium compared with controls (3‐fold and 3.5‐fold respectively). Highest levels were found just before the start of labour. LPS also enhanced the infiltration of neutrophils, macrophages and T cells, and induced macrophage M1 polarization. In vitro studies showed that condition medium from LPS‐treated primary smooth muscle cells (SMC) induced macrophage migration, M1 polarization and upregulated inflammation‐related cytokines such as interleukin (IL)‐1, IL‐6 and tumor necrosis factor alpha (TNF‐α). AMD3100 treatment in pregnant mice led to a significant decrease in the rate of PTL (70%), prolonged pregnancy duration and suppressed macrophage infiltration into gestation tissue by 2.5‐fold. Further, in‐vitro treatment of SMC by AMD3100 suppressed the macrophage migration, decreased polarization and downregulated IL‐1, IL‐6 and TNF‐α expression. LPS treatment in pregnant mice induced PTL by increasing myometrial CXCL12, which recruits immune cells that in turn produce inflammation‐related cytokines. These effects stimulated by LPS were completely reversed by AMD3100 through blocking of CXCL12/CXCR4 signalling. Thus, the CXCL12/CXCR4 axis presents an excellent target for preventing infection and inflammation‐related PTL. 相似文献
98.
Periphytic biomass in a downriver riffle of the Grand River in Southern Ontario, Canada was measured with concrete-block glass slide samplers from May to December 1971. Average rate of accumulation of periphyton on glass slides was 266.2 mg/m2/day ash-free weight, 120.9 mg/m2/day carbon, 20.4 mg/m2/day nitrogen, or 1.11 mg/m2/day chlorophyll a and on concrete blocks was 590.0 mg/m2/day ash-free weight, 202.9 mg/m2/day carbon, 22.8 mg/m2/day nitrogen, or 2.95 mg/m2/day chlorophyll a. The standing biomass of periphyton on glass slides varied from a maximum of 21.6 g/m2 between May 28 and July 15 to a minimum of 0.7 g/m2 in December with an average of 8.6 g/m2. The biomass on concrete blocks ranged from a high of 132.5 g/m2 in August to a low of 29.9 g/m2 in October with a mean of 66.1 g/m2. The well established periphyton on concrete blocks towards the end of the study period was similar to that from native rocks with respect to biomass, carbon and nitrogen contents, and ratios of biomass to chlorophyll a. This suggests that concrete blocks are a better substrate than glass slides for measuring riverbed periphyton. By comparing biomass of periphyton on slides and on concrete blocks, the average rate of loss of periphyton from concrete blocks was estimated to be 2.9 g/m2/day, representing 63% of the mean total accumulation rate of the periphyton. The magnitude of the estimated total loss and the high standing biomass of the periphyton on concrete blocks manifest the importance of the periphyton as a source of organic matter in the river. 相似文献
99.
100.
Caroline M. Williams Hugh A. L. Henry Brent J. Sinclair 《Biological reviews of the Cambridge Philosophical Society》2015,90(1):214-235
Winter is a key driver of individual performance, community composition, and ecological interactions in terrestrial habitats. Although climate change research tends to focus on performance in the growing season, climate change is also modifying winter conditions rapidly. Changes to winter temperatures, the variability of winter conditions, and winter snow cover can interact to induce cold injury, alter energy and water balance, advance or retard phenology, and modify community interactions. Species vary in their susceptibility to these winter drivers, hampering efforts to predict biological responses to climate change. Existing frameworks for predicting the impacts of climate change do not incorporate the complexity of organismal responses to winter. Here, we synthesise organismal responses to winter climate change, and use this synthesis to build a framework to predict exposure and sensitivity to negative impacts. This framework can be used to estimate the vulnerability of species to winter climate change. We describe the importance of relationships between winter conditions and performance during the growing season in determining fitness, and demonstrate how summer and winter processes are linked. Incorporating winter into current models will require concerted effort from theoreticians and empiricists, and the expansion of current growing‐season studies to incorporate winter. 相似文献