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141.
142.
Preliminary gut analysis of a recent Great Lakes invader, the round goby, Neogobius melanostomus (7.0–8.4 cm), collected from
the Detroit River, showed that they ate zebra mussels (58%), snails (6%), and other invertebrates (36%), including aquatic
insects (Hexagenia), softshelled crayfish, and zooplankton. Because zebra mussels, Dreissena polymorpha, predominated as prey,
we investigated the ability of round gobies to consume different size classes of zebra mussels. In laboratory experiments,
we examined feeding preferences of three size classes of round gobies (5.5–6.9 cm; 7.0–8.4 cm; 8.5–10.3 cm standard length)
on four different size classes of zebra mussels (6.0–9.9 mm, 10.0–12.9 mm, 13.0–15.9 mm, 16.0–18.9 mm). All sizes of round
gobies ate zebra mussels < 10.0 mm. Only the largest size class of round gobies ate larger zebra mussels (10.0–12.9 mm) when
all prey sizes were presented. The association between the total mass of zebra mussels available and the amount consumed by
round gobies increased positively up to about 6.5 g of available mussels and then levelled off. Round gobies consumed an average
of 1.0 g of mussels in 24 h. There was a significant positive relationship between gape size and standard length of round
gobies. Although larger round gobies (over the size range of fish in our study) are able to consume larger zebra mussels,
small mussels were preferred. Our findings suggest that the preference of small zebra mussels by round gobies has the potential
to alter the size structure of zebra mussel populations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
143.
We examined whether or not sizes of eggs and offspring were related to emergence date or maternal size in a semelparous aquatic
insect (the burrowing mayfly, Hexagenia) in which parental care is lacking and oviposited eggs are passively dispersed. We quantified the size of males and female
imagos over the emergence span at a site on the Detroit River, Canada, and investigated relationships between emergence date
and female size and (1) egg size and (2) size of first-instar nymphs. Although size of female imagos (H. limbata and H. rigida combined) declined significantly (P<0.025) over the emergence season, there was no significant relationship between body length and emergence date for males
of either species. Males were significantly (P<0.001) smaller than females. H. limbata eggs, subsampled from three individuals from each of three size classes of female imagos collected on seven sampling dates,
were measured using video image analysis. Eggs (n=100) oviposited by each of 63 H. limbata imagos were inspected daily for hatching. Newly hatched nymphs were removed, counted and measured. Egg size (P<0.001) and size of first-instar nymphs (P<0.001) varied significantly with emergence date, but not maternal size. The largest eggs and newly hatched nymphs occurred
at peak emergence of adults. The synchronous release of larger (faster-sinking) eggs may result in reduced predation. Plasticity
in egg development time and egg and nymph size may account for the ability of this taxon to recover from episodes of massive
population reduction.
Received: 12 March 1996 / Accepted: 24 February 1997 相似文献
144.
Lynda J. Burditt Anthony Ratcliffe Patricia R. Fryer Tim E. Hardingham 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1985,844(2):247-255
Pig laryngeal chondrocytes incubated in the presence of monensin showed inhibition of [35S]sulphate incorporation and decreased secretion of proteoglycan into the culture medium, but no large decrease in protein synthesis. This lead to the intracellular accumulation of proteoglycan protein core, which was detected in immunoprecipitates of cell extracts. Using the same antiserum protein core was localised by electron microscopy with protein A-coated gold. In control chondrocytes, it was detected only in elements of the Golgi and in secretory vesicles, but following monensin treatment labelling was more intense in the Golgi and extended into the distended cisternae of the rough endoplasmic reticulum. The results suggest that monensin blocks proteoglycan protein core translocation between different elements of the Golgi and that this occurs prior to the major site of chondroitin sulphate synthesis on proteoglycan. 相似文献
145.
146.
The western Mediterranean region provided the founder population of domesticated narrow-leafed lupin
Mahsa Mousavi-Derazmahalleh Bruno Nevado Philipp E. Bayer Dmitry A. Filatov James K. Hane David Edwards William Erskine Matthew N. Nelson 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2018,131(12):2543-2554
Key message
This study revealed that the western Mediterranean provided the founder population for domesticated narrow-leafed lupin and that genetic diversity decreased significantly during narrow-leafed lupin domestication.Abstract
The evolutionary history of plants during domestication profoundly shaped the genome structure and genetic diversity of today’s crops. Advances in next-generation sequencing technologies allow unprecedented opportunities to understand genome evolution in minor crops, which constitute the majority of plant domestications. A diverse set of 231 wild and domesticated narrow-leafed lupin (Lupinus angustifolius L.) accessions were subjected to genotyping-by-sequencing using diversity arrays technology. Phylogenetic, genome-wide divergence and linkage disequilibrium analyses were applied to identify the founder population of domesticated narrow-leafed lupin and the genome-wide effect of domestication on its genome. We found wild western Mediterranean population as the founder of domesticated narrow-leafed lupin. Domestication was associated with an almost threefold reduction in genome diversity in domesticated accessions compared to their wild relatives. Selective sweep analysis identified no significant footprints of selection around domestication loci. A genome-wide association study identified single nucleotide polymorphism markers associated with pod dehiscence. This new understanding of the genomic consequences of narrow-leafed lupin domestication along with molecular marker tools developed here will assist plant breeders more effectively access wild genetic diversity for crop improvement.147.
Effects of retinoic acid on the development of liver fibrosis produced by carbon tetrachloride in mice 总被引:4,自引:0,他引:4
Wang L Potter JJ Rennie-Tankersley L Novitskiy G Sipes J Mezey E 《Biochimica et biophysica acta》2007,1772(1):66-71
The role of retinoic acid (RA) in liver fibrogenesis was previously studied in cultured hepatic stellate cells (HSCs). RA suppresses the expression of alpha2(I) collagen by means of the activities of specific nuclear receptors RARalpha, RXRbeta and their coregulators. In this study, the effects of RA in fibrogenesis were examined in carbon tetrachloride (CCl4) induced liver fibrosis in mice. Mice were treated with CCl4 or RA and CCl4, along side control groups, for 12weeks. RA reduced the amount of histologically detectable fibrosis produced by CCl4. This was accompanied by a attenuation of the CCl4 induced increase in alpha2(I) collagen mRNA and a lower (2-fold versus 3-fold) increase in liver hydroxyproline. Furthermore, RA reduced the levels of 3-nitrotyrosine (3-NT) protein adducts and thiobarbituric acid (TBA) reactive substance (TBARS) in the liver, which are formed as results of oxidative stress induced by CCl4 treatment. These in vivo findings support our previous in vitro studies in cultured HSC of the inhibitory effect of RA on type I collagen expression. The data also provide evidence that RA reduces CCl4 induced oxidative stress in liver, suggesting that the anti-fibrotic role of RA is not limited to the inhibition of type I collagen expression. 相似文献
148.
149.
150.
Fatima Amanat Shirin Strohmeier Philip S. Meade Nicholas Dambrauskas Barbara Mühlemann Derek J. Smith Vladimir Vigdorovich D. Noah Sather Lynda Coughlan Florian Krammer 《PLoS biology》2021,19(12)
Vaccines against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) have been highly efficient in protecting against Coronavirus Disease 2019 (COVID-19). However, the emergence of viral variants that are more transmissible and, in some cases, escape from neutralizing antibody responses has raised concerns. Here, we evaluated recombinant protein spike antigens derived from wild-type SARS-CoV-2 and from variants B.1.1.7, B.1.351, and P.1 for their immunogenicity and protective effect in vivo against challenge with wild-type SARS-CoV-2 in the mouse model. All proteins induced high neutralizing antibodies against the respective viruses but also induced high cross-neutralizing antibody responses. The decline in neutralizing titers between variants was moderate, with B.1.1.7-vaccinated animals having a maximum fold reduction of 4.8 against B.1.351 virus. P.1 induced the most cross-reactive antibody responses but was also the least immunogenic in terms of homologous neutralization titers. However, all antigens protected from challenge with wild-type SARS-CoV-2 in a mouse model.This study explores the immune response induced by wild type and variant SARS-CoV-2 spike proteins, and the protection that these immune responses provide against challenge with wild type virus in the mouse model. 相似文献