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121.
Once thought to be impossible or a waste of resources, the initial high-volume stages of sequencing the human genome have been completed. 相似文献
122.
Halling BP Yuhas DA Eldridge RR Gilbey SN Deutsch VA Herron JD 《Protein expression and purification》1999,17(3):373-386
Escherichia coli vectors were constructed for the production of a protein complex that mimics the native ecdysone receptor (EcR) isolated from Drosophila. The two steroid receptors, ultraspiracle (USP) and EcR, were expressed as truncations, retaining primarily the hormone binding domains. The recombinant receptor complex was able to mimic the pharmacology of the native receptor with respect to both synthetic and natural agonists. USP and EcR fusion proteins could be expressed in separate cell lines and then recombined following isolation to yield a ligand binding preparation with a dissociation constant (K(D)) for Ponasterone A of 1.5 nM and a total yield of 1.9 pmol ligand binding sites/mg protein. Alternatively, the simultaneous coexpression of both receptors increased yields by several orders of magnitude to 6 nmol ligand binding sites/mg protein with a K(D) of 0.6 nM. Chromatographic analysis under native conditions showed that EcR, when expressed alone, migrated as a variety of complexes, mostly coming out in the void volume as denatured, insoluble, aggregate. In contrast, purified extracts of coexpressed EcR and USP eluted as a single peak with a mobility indicating a heterodimer. The majority of the coexpressed fusion receptors, following purification, formed functional steroid binding sites. A detailed scheme is provided for the expression and isolation of milligram quantities of highly purified receptor dimer. 相似文献
123.
Fear of humans is a source of stress for Holstein dairy cattle and can result when animals are handled aversively. We used aversion learning techniques to determine which handling practices cattle find most aversive. In an aversion race, the cows are repeatedly walked down a race and treatments applied when they reached the end; the time and force required for cows to walk down the race are measured. The animal learns to associate walking down the race with the treatment received; if the treatment is aversive, the animal will take more time and require more force to reach the end of the race than if the treatment is positive. In experiment 1, 54 cows were assigned to four treatments (hit/shout, brushing, control, and food). Treatments of 2-min duration were applied three times a day for 4 days. Cows on the hit/shout treatment took more time and required more force to walk through the race than cows on other treatments, while brushed cows took longer to move through the race than cows given food. In experiment 2, 60 cows were assigned to five treatments (electric prod, shouting, hitting, tail twist, and control). Treatments of 1-min duration were applied three times a day for 3 days. Cows on the shout and electric prod treatments took more time and required more force to walk down the race than cows on the control treatment. In experiment 3, thirty-six 1-1.5-year-old heifers were assigned to three treatments (hand feeding, gentling, or control) applied as in experiment 2. Treatments did not affect the time or force required to walk down the race. The aversion race successfully discriminated between handling treatments that differ greatly in aversiveness but lacked sensitivity to distinguish between treatments that were similar. Although many procedural factors must be considered, aversion learning techniques are an effective method to determine which handling practices cattle find aversive or rewarding. 相似文献
124.
Sunjin Moon Tae-Hun Kim Kyung-Tai Lee Woori Kwak Taeheon Lee Si-Woo Lee Myung-Jick Kim Kyuho Cho Namshin Kim Won-Hyong Chung Samsun Sung Taesung Park Seoae Cho Martien AM Groenen Rasmus Nielsen Yuseob Kim Heebal Kim 《BMC genomics》2015,16(1)
Background
Animal domestication involved drastic phenotypic changes driven by strong artificial selection and also resulted in new populations of breeds, established by humans. This study aims to identify genes that show evidence of recent artificial selection during pig domestication.Results
Whole-genome resequencing of 30 individual pigs from domesticated breeds, Landrace and Yorkshire, and 10 Asian wild boars at ~16-fold coverage was performed resulting in over 4.3 million SNPs for 19,990 genes. We constructed a comprehensive genome map of directional selection by detecting selective sweeps using an FST-based approach that detects directional selection in lineages leading to the domesticated breeds and using a haplotype-based test that detects ongoing selective sweeps within the breeds. We show that candidate genes under selection are significantly enriched for loci implicated in quantitative traits important to pig reproduction and production. The candidate gene with the strongest signals of directional selection belongs to group III of the metabolomics glutamate receptors, known to affect brain functions associated with eating behavior, suggesting that loci under strong selection include loci involved in behaviorial traits in domesticated pigs including tameness.Conclusions
We show that a significant proportion of selection signatures coincide with loci that were previously inferred to affect phenotypic variation in pigs. We further identify functional enrichment related to behavior, such as signal transduction and neuronal activities, for those targets of selection during domestication in pigs.Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1330-x) contains supplementary material, which is available to authorized users. 相似文献125.
LUÍSA C. CARVALHO JOÃO L. COITO SILVANA COLAÇO MAURÍCIO SANGIOGO SARA AMÂNCIO 《Plant, cell & environment》2015,38(4):777-789
Heat stress is a major limiting factor of grapevine production and quality. Acclimation and recovery are essential to ensure plant survival, and the recovery mechanisms can be independent of the heat response mechanisms. An experimental set up with and without acclimation to heat followed by recovery [stepwise acclimation and recovery (SAR) and stepwise recovery (SR), respectively] was applied to two grapevine varieties, Touriga Nacional (TN), and Trincadeira (TR), with different tolerance to abiotic stress. Major differences were found between leaves of SAR and SR, especially after recovery; in SAR, almost all parameters returned to basal levels while in SR they remained altered. Acclimation led to a swifter and short‐term antioxidative response, affecting the plant to a lesser extent than SR. Significant differences were found among varieties: upon stress, TN significantly increased ascorbate and glutathione reduction levels, boosting the cell's redox‐buffering capacity, while TR needed to synthesize both metabolites, its response being insufficient to keep the redox state at working levels. TR was affected by stress for a longer period and the up‐regulation pattern of antioxidative stress genes was more obvious. In TN, heat shock proteins were significantly induced, but the canonical heat‐stress gene signature was not evident probably because no shutdown of the housekeeping metabolism was needed. 相似文献
126.
127.
Many people in the United Arab Emirates store rice in large quantities for long periods of time before use. Five hundred samples
of rice were collected from households in Al-Ain city during the summers of 1992-1994. Aflatoxin B1 was detected in 160 samples (64%) of long grain rice and 81 Samples (32%) of short grain rice at levels ranging from 1.2
to 16.5 μg/kg. The moisture content of samples varied between 5.7% and 15.3%. Species ofAspergillus andPenicillium (includingA. flavus andA. parasiticus) were isolated from discoloured, broken and insect damaged grain and it was confirmed that at least two of the isolates ofA. flavus were aflatoxigenic. These findings demonstrate that rice may contribute to dietary exposure to aflatoxins which are known
to be carcinogenic and immunosuppressive. 相似文献
128.
Glutamine synthetase in the phloem plays a major role in controlling proline production 总被引:16,自引:1,他引:15 下载免费PDF全文
N Brugiere F Dubois AM Limami M Lelandais Y Roux RS Sangwan B Hirel 《The Plant cell》1999,11(10):1995-2012
To inhibit expression specifically in the phloem, a 274-bp fragment of a cDNA (Gln1-5) encoding cytosolic glutamine synthetase (GS1) from tobacco was placed in the antisense orientation downstream of the cytosolic Cu/Zn superoxide dismutase promoter of Nicotiana plumbaginifolia. After Agrobacterium-mediated transformation, two transgenic N. tabacum lines exhibiting reduced levels of GS1 mRNA and GS activity in midribs, stems, and roots were obtained. Immunogold labeling experiments allowed us to verify that the GS protein content was markedly decreased in the phloem companion cells of transformed plants. Moreover, a general decrease in proline content in the transgenic plants in comparison with wild-type tobacco was observed when plants were forced to assimilate large amounts of ammonium. In contrast, no major changes in the concentration of amino acids used for nitrogen transport were apparent. A (15)NH(4)(+)-labeling kinetic over a 48-hr period confirmed that in leaves of transgenic plants, the decrease in proline production was directly related to glutamine availability. After 2 weeks of salt treatment, the transgenic plants had a pronounced stress phenotype, consisting of wilting and bleaching in the older leaves. We conclude that GS in the phloem plays a major role in regulating proline production consistent with the function of proline as a nitrogen source and as a key metabolite synthesized in response to water stress. 相似文献
129.
Abstact Milk and dairy products purchased at Egyptian markets and breast milk from lactating mothers in Cairo and Giza governorates
were analyzed for some mycotoxins. Three of 15 cows’ milk samples were found positive for Afl. M1 with mean value 6.3 ppb. Only one sample of dried milk was positive (5 ppb). Two of 10 hard cheese samples contained detectable
levels of Afl. M1 (3and 6 ppb), whereas one sample containing Afl. B1 and G1 (10 and 4 ppb resp.). For soft cheese one sample of 10 was positive for Afl. M1 (0.5 ppb). Blue veined cheeses were free of Afl. M1 and PR-toxins.
For breast milk two of 10 samples were positive for Afl. M1 (20%) with mean value 2.75 ppb, while 3 of 10 samples were positive for Ochratoxin A (30 %). 相似文献
130.
E N Amuzu-Aweh P Bijma B P Kinghorn A Vereijken J Visscher J AM van Arendonk H Bovenhuis 《Heredity》2013,111(6):530-538
Prediction of heterosis has a long history with mixed success, partly due to low numbers
of genetic markers and/or small data sets. We investigated the prediction of heterosis
for egg number, egg weight and survival days in domestic white Leghorns, using
∼400 000 individuals from 47 crosses and allele frequencies on
∼53 000 genome-wide single nucleotide polymorphisms (SNPs). When heterosis is
due to dominance, and dominance effects are independent of allele frequencies, heterosis
is proportional to the squared difference in allele frequency (SDAF) between parental pure
lines (not necessarily homozygous). Under these assumptions, a linear model including
regression on SDAF partitions crossbred phenotypes into pure-line values and heterosis,
even without pure-line phenotypes. We therefore used models where phenotypes of crossbreds
were regressed on the SDAF between parental lines. Accuracy of prediction was determined
using leave-one-out cross-validation. SDAF predicted heterosis for egg number and weight
with an accuracy of ∼0.5, but did not predict heterosis for survival days. Heterosis
predictions allowed preselection of pure lines before field-testing, saving
∼50% of field-testing cost with only 4% loss in heterosis. Accuracies
from cross-validation were lower than from the model-fit, suggesting that accuracies
previously reported in literature are overestimated. Cross-validation also indicated that
dominance cannot fully explain heterosis. Nevertheless, the dominance model had
considerable accuracy, clearly greater than that of a general/specific combining
ability model. This work also showed that heterosis can be modelled even when pure-line
phenotypes are unavailable. We concluded that SDAF is a useful predictor of heterosis in
commercial layer breeding. 相似文献