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921.
Survase SA Jurgens G van Heiningen A Granström T 《Applied microbiology and biotechnology》2011,91(5):1305-1313
Clostridium beijerinckii DSM 6423 was studied using different continuous production methods to give maximum and stable production of isopropanol and
n-butanol. In a single-stage continuous culture, when wood pulp was added as a cell holding material, we could increase the
solvent productivity from 0.47 to 5.52 g L−1 h−1 with the yield of 54% from glucose. The overall solvent concentration of 7.51 g L−1 (39.4% isopropanol and 60.6% n-butanol) with the maximum solvent productivity of 0.84 g L−1 h−1 was obtained with two-stage continuous culture. We were able to run the process for more than 48 overall retention times
without losing the ability to produce solvents. 相似文献
922.
Zorrilla-Fontanesi Y Cabeza A Domínguez P Medina JJ Valpuesta V Denoyes-Rothan B Sánchez-Sevilla JF Amaya I 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2011,123(5):755-778
Breeding for fruit quality traits in strawberry (Fragaria × ananassa, 2n = 8x = 56) is complex due to the polygenic nature of these traits and the octoploid constitution of this species. In order to
improve the efficiency of genotype selection, the identification of quantitative trait loci (QTL) and associated molecular
markers will constitute a valuable tool for breeding programs. However, the implementation of these markers in breeding programs
depends upon the complexity and stability of QTLs across different environments. In this work, the genetic control of 17 agronomical
and fruit quality traits was investigated in strawberry using a F1 population derived from an intraspecific cross between two contrasting selection lines, ‘232’ and ‘1392’. QTL analyses were
performed over three successive years based on the separate parental linkage maps and a pseudo-testcross strategy. The integrated
strawberry genetic map consists of 338 molecular markers covering 37 linkage groups, thus exceeding the 28 chromosomes. 33
QTLs were identified for 14 of the 17 studied traits and approximately 37% of them were stable over time. For each trait,
1–5 QTLs were identified with individual effects ranging between 9.2 and 30.5% of the phenotypic variation, indicating that
all analysed traits are complex and quantitatively inherited. Many QTLs controlling correlated traits were co-located in homoeology
group V, indicating linkage or pleiotropic effects of loci. Candidate genes for several QTLs controlling yield, anthocyanins,
firmness and l-ascorbic acid are proposed based on both their co-localization and predicted function. We also report conserved QTLs among
strawberry and other Rosaceae based on their syntenic location. 相似文献
923.
Variation in the shell colour and banding polymorphism in the land snail Cepaea nemoralis was studied in 260 populations in the region of Gdańsk, northern Poland. Unlike in other regions of Poland, many populations
contain brown shells. Populations from shaded habitats have higher frequencies of brown than those from open and intermediate
habitats, largely at the expense of yellow shells. Nearly all brown shells are also unbanded. Apart from this disequilibrium,
banding morphs among yellow and pink shells show no relationship to habitat. There are no broad geographical trends in morph-frequencies,
but there are very strong correlations among populations very close together, revealed both by pairwise analysis and Moran’s
I. Principal Component Analyses show that these correlations relate to overall genetic similarity at the loci involved. The
populations are at the north-eastern limits of the species’ range; habitats are mostly anthropogenic, and comparisons with
studies in two urban areas (Wrocław, SW Poland, and Sheffield, central England) suggest that the patterns of variation seen
are a product of human transport of propagules followed by local dispersal. The effect of habitat here is much less marked
than in regions much further west, but it indicates that natural selection has occurred. 相似文献
924.
925.
Paul Bangirana Peter Allebeck Michael J Boivin Chandy C John Connie Page Anna Ehnvall Seggane Musisi 《BMC neurology》2011,11(1):96
Background
Infection with severe malaria in African children is associated with not only a high mortality but also a high risk of cognitive deficits. There is evidence that interventions done a few years after the illness are effective but nothing is known about those done immediately after the illness. We designed a study in which children who had suffered from severe malaria three months earlier were enrolled into a cognitive intervention program and assessed for the immediate benefit in cognitive, academic and behavioral outcomes. 相似文献926.
Masson pine (Pinus massoniana L.) trees in the Pearl River Delta have shown growth decline since late 1980s, particularly those around industrially polluted
regions. As nitrogen is an important nutritional element composing functional proteins, structural proteins and photosynthetic
machinery, investigation on nitrogen allocation is helpful to understand nutrient alteration and its regulation mechanism
in response to pollution stress. Current year (C) and 1-year old needles (C + 1) of five mature trees were sampled in industrially
polluted site and unpolluted natural reserve for bioassay. Needles of declining trees had significantly higher leaf nitrogen
per unit area (NL) but lower photosynthetic capacity (P
max), which resulted in lower photosynthetic nitrogen use efficiency (PNUE) than those of healthy trees. Nitrogen fraction to
the photosynthetic apparatus in the C and C + 1 needles at polluted site was 27 and 22%, significantly lower than the corresponding
healthy needles (48 and 32%). The content of structural proteins was positively correlated with NL in C and C + 1 needles. Moreover, the C and C + 1 needles of declining trees had about 1.8 times structural protein as those
of healthy trees, suggesting that more nitrogen allocation to structural protein are needed for stronger structural defenses
under polluted stress. Decreases in PNUE of declining pine trees could be partially explained by increases in structural protein
nitrogen. 相似文献
927.
928.
Leonardo Mata Helena Gaspar Fátima Justino Rui Santos 《Journal of applied phycology》2011,23(5):827-832
The genus Asparagopsis is a prolific source of halogenated metabolites. Due to its commercial applications, it has been intensively cultivated in southern Portugal. In the present study, we assess if the internal levels of the major halogenated metabolites (bromoform and dibromoacetic acid) in Asparagopsis taxiformis can be increased with hydrogen peroxide (H2O2) addition. Previous studies with red algae showed that the production/release of bromoform can be enhanced by exogenously supplying H2O2. However, no study has assessed if H2O2 supply enhances the content of secondary metabolites within the biomass. This detail is important as the objective of the proposed research is to enhance the content of these valuable metabolites in the produced biomass. Both the activity of the haloperoxidase enzyme and the metabolite content were assessed on short-term and long-term incubation periods to H2O2. To determine the susceptibility of A. taxiformis photosynthetic performance to the imposed oxidative stress, the in vivo fluorescence of photosystem II was monitored. A. taxiformis was shown to be physiologically vulnerable to H2O2, given the observed decrease of the maximum quantum yield of photosynthesis (F v/F m). Contrary to what was expected, the presence of H2O2 inhibited the activity of the iodoperoxidase enzyme. Nevertheless, the extracted halogenated metabolites were higher over the first hours of exposure to H2O2, decreasing after 48 h. These results are probably related to the prosthetic group of the halogenated enzyme in A. taxiformis and the long-term oxidative stress damage of H2O2 exposure. Considering the objective of the proposed research, addition of H2O2 to the cultures, prior (3 h) to biomass harvesting, increases the metabolite content. 相似文献
929.
Leal E Fernández-Durán B Guillot R Ríos D Cerdá-Reverter JM 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2011,181(8):1035-1044
Repetitive aquaculture-related protocols may act as cyclic stressors that induce chronic stress in cultured fish. The sea
bass is particularly sensitive to stressful conditions and the mere presence of humans will disturb feeding behavior. In this
paper, we study whether chronic stress induced by repetition of acute stress protocols affects long-term feeding behavior
and growth performance in sea bass and whether exogenous cortisol may induce stress-like changes in these parameters. We demonstrate
that both chronic stress and dietary cortisol decrease food intake and have a negative effect on feed conversion efficiency,
severely impairing sea bass performance. Both experimental approaches induced changes in the daily feeding activity by lengthening
the active feeding periods. Fish subjected to a cyclic stressor modify their daily feeding pattern in an attempt to avoid
interference with the time of the stressor. The delay in feeding when fish are acutely and repeatedly stressed could be of
substantial adaptive importance. 相似文献
930.
David C. Queller 《Biology & philosophy》2011,26(6):905-913
Biologists and philosophers differ on whether selection should be analyzed at the level of the gene or of the individual. In Peter Godfrey-Smith’s book, Darwinian Populations and Natural Selection, he argues that individuals can be good members of Darwinian populations, whereas genes rarely can. I take issue with parts of this view, and suggest that Godfrey-Smith’s scheme for thinking about Darwinian populations is also applicable to populations of genes. 相似文献