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991.
992.
Beneficial bacteria of agricultural importance 总被引:5,自引:0,他引:5
Olubukola Oluranti Babalola 《Biotechnology letters》2010,32(11):1559-1570
The rhizosphere is the soil–plant root interphase and in practice consists of the soil adhering to the root besides the loose
soil surrounding it. Plant growth-promoting rhizobacteria (PGPR) are potential agents for the biological control of plant
pathogens. A biocontrol strain should be able to protect the host plant from pathogens and fulfill the requirement for strong
colonization. Numerous compounds that are toxic to pathogens, such as HCN, phenazines, pyrrolnitrin, and pyoluteorin as well
as, other enzymes, antibiotics, metabolites and phytohormones are the means by which PGPR act, just as quorum sensing and
chemotaxis which are vital for rhizosphere competence and colonization. The presence of root exudates has a pronounced effect
on the rhizosphere where they serve as an energy source, promoting growth and influencing the root system for the rhizobacteria.
In certain instances they have products that inhibit the growth of soil-borne pathogens to the advantage of the plant root.
A major source of concern is reproducibility in the field due to the complex interaction between the plant (plant species),
microbe and the environment (soil fertility and moisture, day length, light intensity, length of growing season, and temperature).
This review listed most of the documented PGPR genera and discussed their exploitation. 相似文献
993.
This study tests the hypothesis that herd accumulation can be a risk reducing strategy aimed at increasing security in an unpredictable environment. Saami reindeer husbandry in Norway is characterized
by environmental unpredictability and occasionally harsh winters can have dramatic negative effects on reindeer population
densities. While herd accumulation has been found to be an adaptive risk reducing strategy in stochastic environments (i.e.,
individually rational), the accumulation of large herds may also result in collectively negative density dependent effects, which may negatively
affect individual herders (i.e., collectively irrational). We found that individual husbandry units’ strategies, such as accumulating reindeer, have a larger effect on individual husbandry units’ herd size
than a negative density-dependent effect. 相似文献
994.
Tsubasa Fukue Motohide Tamura Ryo Kandori Nobuhiko Kusakabe James H. Hough Jeremy Bailey Douglas C. B. Whittet Philip W. Lucas Yasushi Nakajima Jun Hashimoto 《Origins of life and evolution of the biosphere》2010,40(3):335-346
We present a wide-field (∼6′ × 6′) and deep near-infrared (K
s
band: 2.14 μm) circular polarization image in the Orion nebula, where massive stars and many low-mass stars are forming.
Our results reveal that a high circular polarization region is spatially extended (∼0.4 pc) around the massive star-forming
region, the BN/KL nebula. However, other regions, including the linearly polarized Orion bar, show no significant circular
polarization. Most of the low-mass young stars do not show detectable extended structure in either linear or circular polarization,
in contrast to the BN/KL nebula. If our solar system formed in a massive star-forming region and was irradiated by net circularly
polarized radiation, then enantiomeric excesses could have been induced, through asymmetric photochemistry, in the parent
bodies of the meteorites and subsequently delivered to Earth. These could then have played a role in the development of biological
homochirality on Earth. 相似文献
995.
The distribution of different macroinvertebrate groups inhabiting the littoral zone of 82 mountain lakes in the Pyrenees was
investigated in relation to the altitudinal environmental gradient. For each lake, altitude, longitude and latitude, together
with 28 environmental variables, relating to chemical and physical characteristics and to lake general productivity, were
considered. Using Principal Component Analysis (PCA) we showed that the altitudinal environmental gradient (i.e. altitude
and altitude-related variables) represented the largest gradient of environmental variability. We found that incidence was
related to altitude in about 50% of macroinvertebrate groups, most relationships being inverse, and also that the number of
macroinvertebrate groups found per lake was better described by a second-order polynomial function than by simple linear regression.
However, this relationship was linear for a subset of high-altitude lakes above 2,500 m a.s.l., suggesting an ecological threshold
around this altitude. Redundancy Analyses (RDAs) showed the importance of environmental factors varying with altitude for
the distribution of macroinvertebrate groups. Organic matter, salmonid presence, fine substrate dominance, macrophyte coverage,
temperature and altitude by itself were, in this order, the most relevant factors. Partial RDAs showed that different combinations
of these variables contributed to the explanation of the distribution of each group. However, the variable that uniquely explained
most variability differed from group to group. We conclude that the altitudinal gradient is a multi-faceted ecological factor,
which impinges on each group by means of some specific environmental variable(s) that are particularly relevant for the life
history of that group. 相似文献
996.
997.
Diane M Martin Sébastien Aubourg Marina B Schouwey Laurent Daviet Michel Schalk Omid Toub Steven T Lund Jörg Bohlmann 《BMC plant biology》2010,10(1):226
Background
Terpenoids are among the most important constituents of grape flavour and wine bouquet, and serve as useful metabolite markers in viticulture and enology. Based on the initial 8-fold sequencing of a nearly homozygous Pinot noir inbred line, 89 putative terpenoid synthase genes (VvTPS) were predicted by in silico analysis of the grapevine (Vitis vinifera) genome assembly [1]. The finding of this very large VvTPS family, combined with the importance of terpenoid metabolism for the organoleptic properties of grapevine berries and finished wines, prompted a detailed examination of this gene family at the genomic level as well as an investigation into VvTPS biochemical functions. 相似文献998.
The physico-chemical properties of skim milk containing κ-carrageenan (in the concentration range 0–0.06% w/v), flaxseed gum (in the concentration range 0–0.40% w/v), or a mixture of both polysaccharides were studied using dynamic light scattering, under diluted conditions, as well as
in situ, undiluted, using diffusing wave spectroscopy (DWS) and ultrasonic spectroscopy. Flaxseed gum causes phase separation in
milk mixtures, because of thermodynamic incompatibility between the casein micelles and the polysaccharide chains. Confocal
microscopy and ultrasonic spectroscopy showed that while the addition of 0.01% κ-carrageenan was not sufficient to hinder
phase separation, when 0.03% was added, the helix–helix interactions between κ-carrageenan molecules were sufficient to form
a network and stabilize the system. DWS clearly demonstrated that clusters of casein micelles still form even at very low
concentrations of polysaccharides (below the visible phase separation threshold) and that κ-carrageenan hinders visible phase
separation by decreasing the mobility of the casein micelles. 相似文献
999.
Kwon D Shin K Kim S Ha Y Choi JH Yang JS Lee JY Chae C Oh HB Kang C 《Journal of microbiology (Seoul, Korea)》2010,48(5):657-662
This study aimed to characterize the replication and pathogenic properties of a Korean pandemic (H1N1) 2009 influenza virus
isolate in ferrets and mice. Ferrets infected with A/Korea/01/2009 (H1N1) virus showed mild clinical signs. The virus replicated
well in lungs and slightly in brains with no replication in any other organs. Severe bronchopneumonia and thickening of alveolar
walls were detected in the lungs. Viral antigens were detected in the bronchiolar epithelial cells, in peribronchial glands
with severe peribronchitis and in cells present in the alveoli. A/Korea/01/2009 (H1N1) virus-infected mice showed weight loss
and pathological lung lesions including perivascular cuffing, interstitial pneumonia and alveolitis. The virus replicated
highly in the lungs and slightly in the nasal tissues. Viral antigens were detected in bronchiolar epithelial cells, pneumocytes
and interstitial macrophages. However, seasonal H1N1 influenza virus did not replicate in the lungs of ferrets, and viral
antigens were not detected. Thus, this Korean pandemic (H1N1) 2009 isolate infected the lungs of ferrets and mice successfully
and caused more pathological lesions than did the seasonal influenza virus. 相似文献
1000.
Joanna Skommer Tom Brittain Subhadip Raychaudhuri 《Apoptosis : an international journal on programmed cell death》2010,15(10):1223-1233
BH3 mimetics have been proposed as new anticancer therapeutics. They target anti-apoptotic Bcl-2 proteins, up-regulation of
which has been implicated in the resistance of many cancer cells, particularly leukemia and lymphoma cells, to apoptosis.
Using probabilistic computational modeling of the mitochondrial pathway of apoptosis, verified by single-cell experimental
observations, we develop a model of Bcl-2 inhibition of apoptosis. Our results clarify how Bcl-2 imparts its anti-apoptotic
role by increasing the time-to-death and cell-to-cell variability. We also show that although the commitment to death is highly
impacted by differences in protein levels at the time of stimulation, inherent stochastic fluctuations in apoptotic signaling
are sufficient to induce cell-to-cell variability and to allow single cells to escape death. This study suggests that intrinsic
cell-to-cell stochastic variability in apoptotic signaling is sufficient to cause fractional killing of cancer cells after
exposure to BH3 mimetics. This is an unanticipated facet of cancer chemoresistance. 相似文献