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91.
Interaction for food and space between populations of Galaxias vulgaris Stokell and juvenile Salmo trutta L. in a New Zealand stream 总被引:1,自引:1,他引:0
The trophic and spatial interrelationships between a native ( Galaxias vulguris Stokell, Galaxiidae) and an exotic ( Salmo trutta L., Salmonidae) fish species were investigated over a 24-h period in a New Zealand stream. Interspecific overlap in feeding was greatest at dusk and dawn, as G. vulgaris fed primarily from dusk to post-dawn and S. trutta fed primarily from pre-dawn to post-dusk. Both species fed mainly on benthic and drifting aquatic invertebrates, with larval Deleatidium (Ephemeroptera). Hydora (Coleoptera) and Chironomidae (Diptera) being their preferred prey, although Trichoptera imagos were also preferred by S. trutta . Both species were found primarily in runs and riffles with G. vulgaris occupying slightly shallower (≤0.3 m) and faster (0.3–0.7 m s1 ) waters than did S. trutta (≤0.5 m deep and 0.2–0.4 m s−1 water velocity). We suggest that these rather subtle interspecifc differences in die1 feeding periodicities, diets and microdistributions play a part in lessening the interaction between co-occurring populations of G. wlguris and S. trutta . 相似文献
92.
Sagar V. Gupta Sashi V.P. Kumar Allan L. Stuart Ruili Shi Keith C. Brown Wajdi M. Zoghaib 《Nucleosides, nucleotides & nucleic acids》2013,32(8):1675-1691
Abstract 3′-Azido-2′,3′-dideoxy-5-hydroxymethyluridine (AZHMddUrd) was synthesized to improve the potency of 5-hydroxymethyl-2′-deoxyuridine (HMdUrd) against human immunodeficiency virus (HIV). AZHMddUrd was a very poor inhibitor of HIV replication (ED50 >200 μM) and was also nontoxic up to 400 μM (highest concentration tested) to HT4-6C (HeLa CD4) cells. AZT was phosphorylated by human cellular thymidine kinase. In contrast, AZHMddUrd and HMdUrd were poor substrates for the kinase. The relationship between molecular conformation and antiretroviral activity for 3′-azidothymidine (AZT), HMdUrd and AZHMddUrd is discussed. 相似文献
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Md. Ashaduzzaman Siddikee Puneet S. Chauhan Tongmin Sa 《Journal of Plant Growth Regulation》2012,31(2):265-272
The present study was carried out to understand the mechanism of salt stress amelioration in red pepper plants by inoculation
of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase-producing halotolerant bacteria. In general, ethylene production,
ACC concentration, ACC synthase (ACS), and ACC oxidase (ACO) enzyme activities increased with increasing levels of salt stress.
Treatment with halotolerant bacteria reduced ethylene production by 47–64%, ACC concentration by 47–55% and ACO activity by
18–19% in salt-stressed (150 mmol NaCl) red pepper seedlings compared to uninoculated controls. ACS activity was lower in
red pepper seedlings treated with Bacillus aryabhattai RS341 but higher in seedlings treated with Brevibacterium epidermidis RS15 (44%) and Micrococcus yunnanensis RS222 (23%) under salt-stressed conditions as compared to uninoculated controls. A significant increase was recorded in red
pepper plant growth under salt stress when treated with ACC deaminase-producing halotolerant bacteria as compared to uninoculated
controls. The results of this study collectively suggest that salt stress enhanced ethylene production by increasing enzyme
activities of the ethylene biosynthetic pathway. Inoculation with ACC deaminase-producing halotolerant bacteria plays an important
role in ethylene metabolism, particularly by reducing the ACC concentration, although a direct effect on reducing ACO activity
was also observed. It is suggested that growth promotion in inoculated red pepper plants under inhibitory levels of salt stress
is due to ACC deaminase activity present in the halotolerant bacteria. 相似文献
97.
Vohra PK Hoeppner LH Sagar G Dutta SK Misra S Hubmayr RD Mukhopadhyay D 《American journal of physiology. Lung cellular and molecular physiology》2012,302(2):L185-L192
The neurotransmitter dopamine and its dopamine receptor D2 (D2DR) agonists are known to inhibit vascular permeability factor/vascular endothelial growth factor (VEGF)-mediated angiogenesis and vascular permeability. Lung injury is a clinical syndrome associated with increased microvascular permeability. However, the effects of dopamine on pulmonary edema, a phenomenon critical to the pathophysiology of both acute and chronic lung injuries, have yet to be established. Therefore, we sought to determine the potential therapeutic effects of dopamine in a murine model of lipopolysaccharide (LPS)-induced acute lung injury (ALI). Compared with sham-treated controls, pretreatment with dopamine (50 mg/kg body wt) ameliorated LPS-mediated edema formation and lowered myeloperoxidase activity, a measure of neutrophil infiltration. Moreover, dopamine significantly increased survival rates of LPS-treated mice, from 0-75%. Mechanistically, we found that dopamine acts through the VEGF-VEGFR2 axis to reduce pulmonary edema, as dopamine pretreatment in LPS-treated mice resulted in decreased serum VEGF, VEGFR2 phosphorylation, and endothelial nitric oxide synthase phosphorylation. We used D2DR knockout mice to confirm that dopamine acts through D2DR to block vascular permeability in our lung injury model. As expected, a D2DR agonist failed to reduce pulmonary edema in D2DR(-/-) mice. Taken together, our results suggest that dopamine acts through D2DR to inhibit pulmonary edema-associated vascular permeability, which is mediated through VEGF-VEGFR2 signaling and conveys protective effects in an ALI model. 相似文献
98.
Comparative genomic evidence for a close relationship between the dimorphic prosthecate bacteria Hyphomonas neptunium and Caulobacter crescentus 下载免费PDF全文
Badger JH Hoover TR Brun YV Weiner RM Laub MT Alexandre G Mrázek J Ren Q Paulsen IT Nelson KE Khouri HM Radune D Sosa J Dodson RJ Sullivan SA Rosovitz MJ Madupu R Brinkac LM Durkin AS Daugherty SC Kothari SP Giglio MG Zhou L Haft DH Selengut JD Davidsen TM Yang Q Zafar N Ward NL 《Journal of bacteriology》2006,188(19):6841-6850
The dimorphic prosthecate bacteria (DPB) are alpha-proteobacteria that reproduce in an asymmetric manner rather than by binary fission and are of interest as simple models of development. Prior to this work, the only member of this group for which genome sequence was available was the model freshwater organism Caulobacter crescentus. Here we describe the genome sequence of Hyphomonas neptunium, a marine member of the DPB that differs from C. crescentus in that H. neptunium uses its stalk as a reproductive structure. Genome analysis indicates that this organism shares more genes with C. crescentus than it does with Silicibacter pomeroyi (a closer relative according to 16S rRNA phylogeny), that it relies upon a heterotrophic strategy utilizing a wide range of substrates, that its cell cycle is likely to be regulated in a similar manner to that of C. crescentus, and that the outer membrane complements of H. neptunium and C. crescentus are remarkably similar. H. neptunium swarmer cells are highly motile via a single polar flagellum. With the exception of cheY and cheR, genes required for chemotaxis were absent in the H. neptunium genome. Consistent with this observation, H. neptunium swarmer cells did not respond to any chemotactic stimuli that were tested, which suggests that H. neptunium motility is a random dispersal mechanism for swarmer cells rather than a stimulus-controlled navigation system for locating specific environments. In addition to providing insights into bacterial development, the H. neptunium genome will provide an important resource for the study of other interesting biological processes including chromosome segregation, polar growth, and cell aging. 相似文献
99.
In Vivo Fitness Cost of the M184V Mutation in Multidrug-Resistant Human Immunodeficiency Virus Type 1 in the Absence of Lamivudine 总被引:1,自引:0,他引:1
100.
Behzad Etemad Angela Fellows Brenda Kwambana Anupa Kamat Yang Feng Sandra Lee Manish Sagar 《Journal of virology》2009,83(19):9694-9708