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排序方式: 共有250条查询结果,搜索用时 625 毫秒
41.
Paul M Kulesa Jessica M Teddy Miranda Smith Richard Alexander Cameron HJ Cooper Rusty Lansford Rebecca McLennan 《BMC developmental biology》2010,10(1):101
Background
Tracing cell dynamics in the embryo becomes tremendously difficult when cell trajectories cross in space and time and tissue density obscure individual cell borders. Here, we used the chick neural crest (NC) as a model to test multicolor cell labeling and multispectral confocal imaging strategies to overcome these roadblocks. 相似文献42.
An immunoblot (IB) technique for detecting antibodies to Streptobacillus moniliformis in rat sera was evaluated. Immune sera to three S. moniliformis strains showed a similar reactivity pattern with both autologous and homologous antigens in the 18-87 kDa range. Using a rat S. moniliformis strain as the antigen, a similar reactivity pattern was found with sera from rats infected experimentally with S. moniliformis and sentinels. Two to five proteins were detected in the 32-55 kDa range. Over a period of 2.5 years, 27/133 rat serum panels submitted for routine monitoring yielded one or more S. moniliformis enzyme-linked immunosorbent assay (ELISA)-positive samples. In one of these 27 panels, sera showed an IB reactivity pattern resembling that observed with immune sera and with sera from infected and exposed rats. S. moniliformis was confirmed in the colony by both culture and polymerase chain reaction (PCR). Sera from the remaining 26 ELISA-positive serum panels frequently showed activity to a 57 kDa antigen but not more than one antigen was detected in the 32-55 kDa range. We conclude that the IB can be used as a confirmatory test for the detection of S. moniliformis infection in ELISA-positive rats. 相似文献
43.
Background
The accuracy of genomic prediction depends largely on the number of animals with phenotypes and genotypes. In some industries, such as sheep and beef cattle, data are often available from a mixture of breeds, multiple strains within a breed or from crossbred animals. The objective of this study was to compare the accuracy of genomic prediction for several economically important traits in sheep when using data from purebreds, crossbreds or a combination of those in a reference population.Methods
The reference populations were purebred Merinos, crossbreds of Border Leicester (BL), Poll Dorset (PD) or White Suffolk (WS) with Merinos and combinations of purebred and crossbred animals. Genomic breeding values (GBV) were calculated based on genomic best linear unbiased prediction (GBLUP), using a genomic relationship matrix calculated based on 48 599 Ovine SNP (single nucleotide polymorphisms) genotypes. The accuracy of GBV was assessed in a group of purebred industry sires based on the correlation coefficient between GBV and accurate estimated breeding values based on progeny records.Results
The accuracy of GBV for Merino sires increased with a larger purebred Merino reference population, but decreased when a large purebred Merino reference population was augmented with records from crossbred animals. The GBV accuracy for BL, PD and WS breeds based on crossbred data was the same or tended to decrease when more purebred Merinos were added to the crossbred reference population. The prediction accuracy for a particular breed was close to zero when the reference population did not contain any haplotypes of the target breed, except for some low accuracies that were obtained when predicting PD from WS and vice versa.Conclusions
This study demonstrates that crossbred animals can be used for genomic prediction of purebred animals using 50 k SNP marker density and GBLUP, but crossbred data provided lower accuracy than purebred data. Including data from distant breeds in a reference population had a neutral to slightly negative effect on the accuracy of genomic prediction. Accounting for differences in marker allele frequencies between breeds had only a small effect on the accuracy of genomic prediction from crossbred or combined crossbred and purebred reference populations. 相似文献44.
Jantien van Berkel Cécile R. L. Boot Karin I. Proper Paulien M. Bongers Allard J. van der Beek 《PloS one》2014,9(1)
Objectives
The aim of the present study was to evaluate the effectiveness of a worksite mindfulness-related multi-component health promotion intervention on work engagement, mental health, need for recovery and mindfulness.Methods
In a randomized controlled trial design, 257 workers of two research institutes participated. The intervention group (n = 129) received a targeted mindfulness-related training, followed by e-coaching. The total duration of the intervention was 6 months. Data on work engagement, mental health, need for recovery and mindfulness were collected using questionnaires at baseline and after 6 and 12 months follow-up. Effects were analyzed using linear mixed effect models.Results
There were no significant differences in work engagement, mental health, need for recovery and mindfulness between the intervention and control group after either 6- or 12-months follow-up. Additional analyses in mindfulness-related training compliance subgroups (high and low compliance versus the control group as a reference) and subgroups based on baseline work engagement scores showed no significant differences either.Conclusions
This study did not show an effect of this worksite mindfulness-related multi-component health promotion intervention on work engagement, mental health, need for recovery and mindfulness after 6 and 12 months.Trial registration
Netherlands Trial Register NTR2199 相似文献45.
46.
The small-subunit ribosomal RNA gene sequences from the hypotrichous ciliates Oxytricha nova and Stylonychia pustulata 总被引:17,自引:0,他引:17
We have determined the complete nucleotide sequence of the small- subunit
ribosomal RNA genes for the ciliate protozoans Stylonychia pustulata and
Oxytricha nova. The sequences are homologous and sufficiently similar that
these organisms must be closely related. In a phylogeny inferred from
comparisons of several eukaryotic small-subunit ribosomal RNAs, the
divergence of the ciliates from the eukaryotic line of descent is seen to
coincide with the radiation of the plants, the animals, and the fungi. This
radiation is preceded by the divergence of the slime mold, Dictyostelium
discoideum.
相似文献
47.
DNA damage‐induced replication stress results in PA200‐proteasome‐mediated degradation of acetylated histones 下载免费PDF全文
48.
Growth and carbon economy of a fast-growing and a slow-growing grass species as dependent on nitrate supply 总被引:5,自引:0,他引:5
Hendrik Poorter Claudius A. D. M. van de Vijver René G. A. Boot Hans Lambers 《Plant and Soil》1995,171(2):217-227
In previous experiments systematic differences have been found in the morphology, carbon economy and chemical composition
of seedlings of inherently fast- and slow-growing plant species, grown at a non-limiting nutrient supply. In the present experiment
it was investigated whether these differences persist when plants are grown at suboptimal nutrient supply rates. To this end,
plants of the inherently fast-growing Holcus lanatus L. and the inherently slow-growing Deschampsia flexuosa (L.) Trin. were grown in sand at two levels of nitrate supply. Growth, photosynthesis, respiration and carbon and nitrogen
content were studied over a period of 4 to 7 weeks.
At low N-supply, the potentially fast-growing species still grew faster than the potentially slow-growing one. Similarly,
differences in leaf area ratio (leaf area:total dry weight), specific leaf area (leaf area:leaf dry weight) and leaf weight
ratio (leaf dry weight:total dry weight), as observed at high N-supply persisted at low N-availability. The only growth parameter
for which a substantial Species × N-supply interaction was found was the net assimilation rate (increase in dry weight per
unit leaf area and time). Rates of photosynthesis, shoot respiration and root respiration, expressed per unit leaf, shoot
and root weight, respectively, were lower for the plants at low N-availability and higher for the fast-growing species. Species-specific
variation in the daily carbon budget was mainly due to variation in carbon fixation. Lower values at low N were largely determined
by both a lower C-gain of the leaves and a higher proportion of the daily gain spent in root respiration.
Interspecific variation in C-content and dry weight:fresh weight ratio were similar at low and high N-supply. Total plant
organic N decreased with decreasing N-supply, without differences between species. It is concluded that most of the parameters
related to growth, C-economy and chemical composition differ between species and/or are affected by N-supply, but that differences
between the two species at high N-availability persist at low N-supply. 相似文献
49.
Summary The purpose of this study was characterizing the phototoxic action of protoporphyrin and cellular protection mechanisms, as
studied on the cellular level. In this process, active oxygen is involved. As a biological system, rat hepatocyte shortterm
and primary cultures were used. Phototoxicity of protoporphyrin could be observed, after previous absorption of protoporphyrin
to membrane structures. Damaging of several cell organelles occurred, such as mitochondria and lysosomes. Peroxisomes were
not affected. Coated vesicles located at the periphery of the cells’ interior suggested that protoporphyrin absorption is
mediated by an active uptake (endocytosis), as well as passive diffusion. Lipid peroxidation played a role in protoporphyrin
photoxicity. Cellular protection mechanisms such as superoxide dismutase and the scavenger glutathione (GSH) protected the
cells from active oxygen toxicity.
In conclusion, protoporphyrin entered the cells by diffusion and endocytosis. Previous adsorption to the membrane structures
was necessary for the expression of protoporphyrin phototoxicity. However, active oxygen itself could not be demonstrated.
Lipid peroxidation was involved in cell-damaging processes. Mechanisms of protoporphyrin phototoxicity on the cellular level
were studied. Rat hepatocyte primary and short-term cultures proved to be suitablein vitro systems for studying biochemical and morphological effects on the cellular level.
This article is based on PhD research carried out at the Department of Veterinary Pharmacology, Pharmacy and Toxicology, Utrecht
University, The Netherlands. 相似文献
50.
Paula van Dommelen Jennifer K. Coffeng Hidde P. van der Ploeg Allard J. van der Beek Cécile R. L. Boot Ingrid J. M. Hendriksen 《PloS one》2016,11(3)