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301.
Leppänen AS Niittymäki O Parikka K Tenkanen M Eklund P Sjöholm R Willför S 《Carbohydrate research》2010,345(18):2610-2615
The C-6 unit of methyl α-d-galactopyranoside was selectively modified by combining enzymatic oxidation with an indium-mediated allylation reaction. The Barbier-Grignard type reaction, where a carbonyl group reacts with an allyl halide, proceeds in aqueous solution, even with water as the only solvent; thus carbohydrates can be modified without the need for drying or protection-deprotection steps. The corresponding homoallyl alcohols are produced in high yields of >90% in the reactions with allyl bromide and cinnamyl chloride. The main products were isolated and characterized by GC-MS and NMR spectroscopy. 相似文献
302.
Why do plants abort so many developing seeds: bad offspring or bad maternal genotypes? 总被引:1,自引:0,他引:1
It has been suggested that abortion of ovules in perennials is caused partly by early acting genetic load (abortions due to
‘bad offspring’). However, it is still unclear what proportion of abortions of naturally pollinated seeds are due to early
genetic load. Here we suggest that variation between maternal genotypes (abortions due to ‘bad maternal genotypes’) may be
an even more important factor causing genetic abortions than early load, based on results from Scots pine. The early load
is severe in Scots pine: in experimental self-pollinations on average 76% of the seeds were aborted. Comparison of naturally
pollinated and experimentally cross-pollinated seeds showed that the abortion rate of naturally pollinated seeds was only
slightly, and not statistically significantly, higher than that of experimentally cross-pollinated seeds (30% vs. 26.5%, respectively).
Thus, although early load can be high under self-pollination in Scots pine, it does not account for a high share of abortions
of naturally pollinated seeds. Instead, maternal genotype determined the seed abortion rate: in a separate experiment using
an experimental population (clonal stand), 29% of the total variance in seed abortion was due to variation between maternal
genotypes. We studied further whether ‘bad maternal genotypes’ could be explained by trade-offs between seed abortion and
other fitness functions. Only one statistically significant genetic correlation was found, a positive association between
cone production and successful seed development. Thus ‘bad maternal genotypes’ aborted a higher proportion of their seed and
produced less cones than the ‘good maternal genotypes’.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
303.
Outi K Hallikas Johanna M Aaltonen Harriet von Koskull Lars-Axel Lindberg Leena Valmu Nisse Kalkkinen Torsten Wahlstr?m Hiroaki Kataoka Leif Andersson Dan Lindholm Jim Schr?der 《The journal of histochemistry and cytochemistry》2006,54(7):745-752
Syncytiotrophoblast and invasive extravillous trophoblast arise from a common stem cell, namely villous cytotrophoblast, but have very different characteristics. The study of the differentiation process relies on the availability of suitable markers for these different cell types of developing placenta. In this work, we have produced monoclonal antibodies that are specific to human villous cytotrophoblast. Monoclonal antibody (MAb) MG2 was specific to villous cytotrophoblast across gestation, and recognizes hepatocyte growth factor activator inhibitor type 1. MAb MD10 stained villous cytotrophoblast across gestation and also some endothelial cells, particularly in the second or third trimester. MAb MD10 recognizes human integrin alpha6beta4. As a test for specificity, the novel MAbs were also used for staining of frozen tissue from human colon carcinoma. The results show that the two antibodies can be used as tools to study human villous cytotrophoblasts and also human tumors. The MG2 antibody seems most specific and promising for the study of various aspects of human villous cytotrophoblast. 相似文献
304.
305.
Mollie K. Manier John M. Belote Kirstin S. Berben Stefan Lüpold Outi Ala‐Honkola William F. Collins Scott Pitnick 《Evolution; international journal of organic evolution》2013,67(8):2348-2362
Postcopulatory sexual selection is credited with driving rapid evolutionary diversification of reproductive traits and the formation of reproductive isolating barriers between species. This judgment, however, has largely been inferred rather than demonstrated due to general lack of knowledge about processes and traits underlying variation in competitive fertilization success. Here, we resolved processes determining sperm fate in twice‐mated females, using transgenic Drosophila simulans and Drosophila mauritiana populations with fluorescently labeled sperm heads. Comparisons among these two species and Drosophila melanogaster revealed a shared motif in the mechanisms of sperm precedence, with postcopulatory sexual selection potentially occurring during any of the three discrete stages: (1) insemination; (2) sperm storage; and (3) sperm use for fertilization, and involving four distinct phenomena: (1) sperm transfer; (2) sperm displacement; (3) sperm ejection; and (4) sperm selection for fertilizations. Yet, underlying the qualitative similarities were significant quantitative differences in nearly every relevant character and process. We evaluate these species differences in light of concurrent investigations of within‐population variation in competitive fertilization success and postmating/prezygotic reproductive isolation in hybrid matings between species to forge an understanding of the relationship between microevolutionary processes and macroevolutionary patterns as pertains to postcopulatory sexual selection in this group. 相似文献
306.
Janne Atosuo Outi Karhuvaara Eetu Suominen Liisa Viln Jari Nuutila Tuula Putus 《Innate immunity》2021,27(1):15
In this comparative study, serum complement system antimicrobial activity was measured from 159 serum samples, taken from individuals from microbe-damaged (70 samples) and from reference buildings (89 samples). Antimicrobial activity was assessed using a probe-based bacterial Escherichia coli-lux bioluminescence system and comparison was made at a group level between the experimental and reference group. The complement activity was higher in users of microbe-damaged buildings compared with the reference group and the significant (P < 0.001) increase in activity was found in the classical reaction pathway. This study strengthens our notion that exposure to indoor-related microbe damage increases the risk for systemic subclinical inflammation and creates a health risk for building users. 相似文献
307.
308.
309.
Isozyme variability was examined in 13 geographically isolated populations of the endemic arctic hairy lousewort (Pedicularis dasyantha) in the Svalbard Archipelago, 80° N latitude, Norway. Of the 23 enzyme systems screened on five buffer systems 18 were interpretable. Of the 31 reliable loci, only 6-phosphogluconate dehydrogenase (6-Pgd), was polymorphic. However, no heterozygotes were detected. Frequencies for allele 1 among the populations varied from 1.00 in the north to 0.00 in the south and 0.53 in the central “overlap” region. At the species level the mean number of alleles per locus (A) was 1.03. Percentage of polymorphic loci (P) was 3%. Expected heterozygosity (He) was 0.016. At the population level the mean number of alleles per locus was 1.01, and 1.1% of the loci were polymorphic. He was 0.004. These values are low compared to endemic, widespread, selling, and outcrossed species. Flower color morphs were distinct. They varied within and among the 13 populations. The frequency of color morphs coincided with allele frequencies of 6-PGD: allele 1 was found in dark purple morphs, and allele 2 was found in light morphs. This species shows more isozyme genetic variability than the five other species reported in the genus but generally less variation than other species with limited regional distributions. Low-level genetic variation in this diploid species may be a result of colonization events coupled with genetic drift, founder effects, and strong natural selection. Additional factors include the self-compatible reproductive system and the long-lived perennial habit. 相似文献
310.
The case details and outcome after surgical decompression of 46 dogs with thoracolumbar intervertebral disc disease with loss
of deep pain perception prior to surgery were reviewed. Nineteen dogs (41.3%) recovered with a median follow-up period of
12.5 months. Recovery was defined as an ambulatory paraparesis, or better, with urinary and fecal continence. There was a
better outcome in dogs with loss of deep pain for less than 24 hours prior to surgery (19/41; 46.3% recovered) than in dogs
without deep pain perception for more than 24 hours (0/5; 0% recovered). Dogs with deep pain perception present at two weeks
postoperatively had significantly higher success rate (8/12; 66.7% recovered) than dogs without deep pain perception at this
time period (1/10; 10.0% recovered). The return of deep pain perception by two weeks postoperatively can be a useful positive
prognostic indicator. 相似文献