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151.
Studies of fluctuations in total organic carbon (TOC) were performedin both the reference basin and the acidified basin of experimental LakeSkjervatjern, in order to separate effects of various catchment and in-lakeprocesses. Nearly five years of catchment acidification did not inducesignificant changes in TOC. TOC concentrations was not related clearly toprecipitation or runoff. In both basins, there was a regular, seasonal patternwith a gradual increase in TOC concentrations from spring to late autumn.Minima in concentrations occurred during periods with frozen ground inwinter, irrespective of discharge patterns. The decrease from 10 mg C l-1 in autumn to 1--2 mg C l-1 in latewinter, was only seen in surface layers. Runoff was the major loss routefor surface TOC in the lake. Photo-oxidation, bacterial oxidation, andsedimentation combined yielded maximum loss rates of 3%of surface TOC d-1. Below a depth of 1 m 0.5%d-1 was lost to these same processes. The surface microlayerhad 5--10 times more TOC than the bulk water on average, and could haveeffects on gas exchange and sub-surface light. Despite the oxidation ofTOC, the short residence time of the lake and rapid replacement of TOCfrom the catchment was the major determinant of lake water TOC. 相似文献
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Two adjacent inversions maintain genomic differentiation between migratory and stationary ecotypes of Atlantic cod
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Tina Graceline Kirubakaran Harald Grove Matthew P. Kent Simen R. Sandve Matthew Baranski Torfinn Nome Maria Cristina De Rosa Benedetta Righino Torild Johansen Håkon Otterå Anna Sonesson Sigbjørn Lien Øivind Andersen 《Molecular ecology》2016,25(10):2130-2143
Atlantic cod is composed of multiple migratory and stationary populations widely distributed in the North Atlantic Ocean. The Northeast Arctic cod (NEAC) population in the Barents Sea undertakes annual spawning migrations to the northern Norwegian coast. Although spawning occurs sympatrically with the stationary Norwegian coastal cod (NCC), phenotypic and genetic differences between NEAC and NCC are maintained. In this study, we resolve the enigma by revealing the mechanisms underlying these differences. Extended linkage disequilibrium (LD) and population divergence were demonstrated in a 17.4‐Mb region on linkage group 1 (LG1) based on genotypes of 494 SNPs from 192 parents of farmed families of NEAC, NCC or NEACxNCC crosses. Linkage analyses revealed two adjacent inversions within this region that repress meiotic recombination in NEACxNCC crosses. We identified a NEAC‐specific haplotype consisting of 186 SNPs that was fixed in NEAC sampled from the Barents Sea, but segregating under Hardy–Weinberg equilibrium in eight NCC stocks. Comparative genomic analyses determine the NEAC configuration of the inversions to be the derived state and date it to ~1.6–2.0 Mya. The haplotype block harbours 763 genes, including candidates regulating swim bladder pressure, haem synthesis and skeletal muscle organization conferring adaptation to long‐distance migrations and vertical movements down to large depths. Our results suggest that the migratory ecotype experiences strong directional selection for the two adjacent inversions on LG1. Despite interbreeding between NEAC and NCC, the inversions are maintaining genetic differentiation, and we hypothesize the co‐occurrence of multiple adaptive alleles forming a ‘supergene’ in the NEAC population. 相似文献
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Background
Ingestion of AndoSan™, based on the mushroom Agaricus blazei Murill, has previously been shown to exhibit anti-inflammatory effects because of reduction of pro-inflammatory cytokines in healthy individuals and patients with ulcerative colitis. In this randomized single-blinded placebo controlled study we examined whether intake of AndoSan™ also resulted in clinical effects.Methods and Findings
50 patients with symptomatic ulcerative colitis were block-randomized and blinded for oral daily intake of AndoSan™ or placebo for the 21 days’ experimental period. The patients reported scores for symptoms, fatigue and health related quality of life (HRQoL) at days 0, 14 and 21. Fecal calprotectin and general blood parameters were also analyzed. In the AndoSan™ group (n = 24) symptoms improved from baseline (day 0) to days 14 and 21, with respective mean scores (95% CI) of 5.88 (4.92–6.83), 4.71 (3.90–5.52) (p = 0.002) and 4.50 (3.70–5.30) (p = 0.001). Corresponding improved mean scores (±SD) for total fatigue were 16.6 (5.59), 14.1 (4.50) (p = 0.001) and 15.1 (4.09) (p = 0.023). These scores in the placebo group (n = 26) were not improved. When comparing the two study groups using mixed model statistics, we found significant better scores for the AndoSan™-patients. HRQoL for dimensions bodily pain, vitality, social functioning and mental health improved in the AndoSan™ group. There were no alterations in general blood samples and fecal calprotectin.Conclusions
Beneficiary effects on symptoms, fatigue and HRQoL from AndoSan™ consumption were demonstrated in this per-protocol study, supporting its use as a supplement to conventional medication for patients with mild to moderate symptoms from ulcerative colitis. The patients did not report any harms or unintended effects of AndoSan™ in this study.Trial Registration
ClinicalTrials.gov NCT01496053相似文献157.
Else Nøst Hegseth Egil Sakshaug 《Journal of experimental marine biology and ecology》1983,67(3):199-220
Three species of diatoms, Skeletonema costatum (Grev.) Cleve, Thalassiosira gravida Cleve, and T. pseudonana (Hustedt) Hasle et Heimdal, were grown in in situ dialysis culture in the Trondheimsfjord at depths of 0.5 and 4 m. The rates of growth and the chemical composition of exponentially growing cells were monitored and related to seasonal changes in illumination and temperature. Functions correlating growth rate with temperature were deduced. Growth took place from February to November. During this period temperature ranged from ?1 to 16°C, the average photon flux density (ifI) (per 24 h) from 9 to 570 μE · m?2 · s?1 (0.5 m depth), and the length of the days (I > 1 μE · m?2 · s?1) from 6 to 24 h. Light-limited growth was evident when the product of the average daily light and the chlorophyll/N ratio was < 10; this occurred mostly in early spring and late autumn. Peak densities (> 800 for the Thalassiosira spp. and > 1300–1400 μE · m?2 · s?1 for Skeletonema) seem to inhibit growth. The highest rates recorded were ≈1.6 doubl. · day?1 (July, 15–16°C).The three species exhibit different ecological behaviour. Skeletonema is eurythermal (Q10 = 1.8), whereas Thalassiosira pseudonana favours high temperatures, and T. gravida temperatures < 10°C. Moreover, Skeletonema has generally less chlorophyll and more phosphorus and ATP (≈ 1.4 ×) than the other two species. In Skeletonema, the ATP level seems related to the light-governed growth rate, and independent of temperature. In Thalassiosira no such correlation was found. 相似文献
158.
George W. Francis Linda P. Strand Torleiv Lien Gjert Knutsen 《Archives of microbiology》1975,104(1):249-254
Synchronous cultures of Chlamydomonas reinhardii have been examined for the total amounts of carotenoid and chlorophyll present throughout a 12 hrs light–4 hrs dark life cycle. Variations in the carotenoid distribution at different points within the cell cycle have been found. During the greater part of the light period all major carotenoids increased at a proportionally similar rate. However, the increases in lutein and violaxanthin preceded those in β-carotene and neoxanthin by some 2 hrs and that in loroxanthin, an algal xanthophyll, by about 3 hrs. A marked drop in total carotenoid accumulation, corresponding to similar temporary falling away in the accumulation of β-carotene, lutein and violaxanthin occurred at 9 hrs. The correspondence of this with the established drop in RNA accumulation and the break-up of the nucleolus was pointed out. Considerable redistribution among the carotenoids occurred during the dark period, notably the amount of β-carotene increased relative to the total xanthophylls. The full significance of these results can not be estimated in the absence of comparative data on related organisms. 相似文献
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Last December marked the 20th anniversary of the Nobel Prize in Chemistry to Sidney Altman and Thomas Cech for their discovery of RNA catalysts in bacterial ribonuclease P (an enzyme catalyzing 5′ maturation of tRNAs) and a self-splicing rRNA of Tetrahymena, respectively. Coinciding with the publication of a treatise on RNase P,1 this review provides a historical narrative, a brief report on our current knowledge, and a discussion of some research prospects on RNase P.
“…the great thing about science is that you can actually solve a problem. You can take something which is confused, a mess, and not only find a solution, but prove it's the right one.”2
-Sydney Brenner
“In research the front line is almost always in a fog.”3
-Francis Crick相似文献