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51.
The NMR spectra of nucleic acids suffer from severe peak overlap, which complicates resonance assignments. 4D NMR experiments can overcome much of the degeneracy in 2D and 3D spectra; however, the linear increase in acquisition time with each new dimension makes it impractical to acquire high-resolution 4D spectra using standard Fourier transform (FT) techniques. The filter diagonalization method (FDM) is a numerically efficient algorithm that fits the entire multi-dimensional time-domain data to a set of multi-dimensional oscillators. Selective 4D constant-time HCCH-COSY experiments that correlate the H5-C5-C6-H6 base spin systems of pyrimidines or the H1'-C1'-C2'-H2' spin systems of ribose sugars were acquired on the (13)C-labeled iron responsive element (IRE) RNA. FDM-processing of these 4D experiments recorded with only 8 complex points in the indirect dimensions showed superior spectral resolution than FT-processed spectra. Practical aspects of obtaining optimal FDM-processed spectra are discussed. The results here demonstrate that FDM-processing can be used to obtain high-resolution 4D spectra on a medium sized RNA in a fraction of the acquisition time normally required for high-resolution, high-dimensional spectra. 相似文献
52.
Gill raker morphology of a benthophagous fish Goniistius zonatus (Cheilodactylidae) (10.9–29.2 cm SL), using a filter-feeding mode, was compared between two locations (Morode and Arakashi)
in southern Japan. Although gill raker number and gill raker length at the two locations did not differ, gill raker spacing
was narrower relative to overall fish size at Morode than at Arakashi, mainly because gill raker width was greater at Morode.
The difference of gill raker spacing is unlikely to have a genetic or physiochemical explanation. Small invertebrates (≤1.0
mm) were dominant on the substrate at Morode but were less common at Arakashi. Such small animals were consumed by many fish
at Morode but were rarely exploited at Arakashi. At Morode, the narrow gill raker spacing would be effective in retaining
small prey, which should be an important energy resource in this population. The difference of interraker spacing at the two
locations seems to be related to available prey size at each location.
Received: November 14, 2000 / Revised: February 13, 2001 / Accepted: February 28, 2001 相似文献
53.
Simplex‐based optimization of numerical and categorical inputs in early bioprocess development: Case studies in HT chromatography 下载免费PDF全文
Bioprocess development studies often involve the investigation of numerical and categorical inputs via the adoption of Design of Experiments (DoE) techniques. An attractive alternative is the deployment of a grid compatible Simplex variant which has been shown to yield optima rapidly and consistently. In this work, the method is combined with dummy variables and it is deployed in three case studies wherein spaces are comprised of both categorical and numerical inputs, a situation intractable by traditional Simplex methods. The first study employs in silico data and lays out the dummy variable methodology. The latter two employ experimental data from chromatography based studies performed with the filter‐plate and miniature column High Throughput (HT) techniques. The solute of interest in the former case study was a monoclonal antibody whereas the latter dealt with the separation of a binary system of model proteins. The implemented approach prevented the stranding of the Simplex method at local optima, due to the arbitrary handling of the categorical inputs, and allowed for the concurrent optimization of numerical and categorical, multilevel and/or dichotomous, inputs. The deployment of the Simplex method, combined with dummy variables, was therefore entirely successful in identifying and characterizing global optima in all three case studies. The Simplex‐based method was further shown to be of equivalent efficiency to a DoE‐based approach, represented here by D‐Optimal designs. Such an approach failed, however, to both capture trends and identify optima, and led to poor operating conditions. It is suggested that the Simplex‐variant is suited to development activities involving numerical and categorical inputs in early bioprocess development. 相似文献
54.
Quantification of ingestion by grazing and by filtration in Crepidula fecunda showed that during the motile phase of the life cycle (<28 mm in shell length), the species depends on both feeding strategies to supply it's energetic requirements. This species improves the energetic quality of the material ingested by exercising preferential selection for organic material from all the materials that are available on the substrate, with an average organic enrichment of 13%. The ontogenetic change in the relative importance of grazing and filter feeding appear to be species-specific within the genus; some species have motile forms in earlier life stages which need to move about the substrate to obtain food and locate aggregations of conspecifics. After growing to about 28 mm in length, C. fecunda become sessile females and depend solely on filter feeding to meet their nutritional requirements. 相似文献
55.
The rates of emergence of wheat and lupin were measured in 13 field experiments on water repellent sands. Conventional sowing
was compared with furrow sowing either with or without the use of a press wheel and several rates of banded wetting agent.
Measurements included, severity of water repellence, plant emergence, rainfall, soil temperature at sowing and, at one site,
the area of wet soil after sowing. All ameliorative techniques improved emergence, with responses being greatest when seeds
were sown into dry soil. Compared with conventional sowing, furrow sowing increased wheat and lupin emergence by an overall
average of 16 and 41%, respectively. The benefits were greater at the drier sites. Increases in emergence due to the use of
a press wheel were sometimes small, although they always occurred (1–19%). It was visually observed that press wheel use gave
more uniform seeding depth, reduced clods and ensured more accurate placement of banded wetting agent. Banded wetting agent
consistently improved wheat and lupin emergence, particularly where early rains were light and press wheels were used. The
wetting agent increased the cross-sectional area of wet topsoil (0–10 cm) which was positively related with increased wheat
emergence (R2 = 0.91). At 0.5 L ha−1 of banded wetting agent, the soil along the furrow was four times wetter than without wetting agent. Wetting agent at 0.5
and 1 L ha−1 (with press wheels) increased wheat emergence by 6 and 11% and lupin emergence by 13 and 11%, respectively. The high rates
of banded wetting agent gave highest plant densities. Grain yield was only measured at three sites. Furrow sowing did not
increase grain yield, however, press wheels use with furrow sowing increased grain yield by 30%. Banded wetting agent increased
grain yield and they were positively correlated. The highest rate increased grain yields by a further 9% above press wheels
and furrow sowing.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
56.
The study compared the centre of pressure measurements (COP) and vertical ground reaction forces (vGRF) from a pressure insole system to that from force plates (FP) during two flywheel quadriceps resistance exercises: leg press and squat. The comparison was performed using a motion capture system and simultaneous measurements of COP and vGRF from FP and insoles. At lower insole-vGRF (<250 N/insole) COP accuracy deteriorated and those data were excluded from further analysis. The insoles systematically displaced the COP slightly posteriorly and medially compared to the FP measurements. Pearson’s coefficient of correlation (r) between insole- and FP-COP showed good agreement in both the anteroposterior (squat: r = 0.96, leg press: r = 0.97) and mediolateral direction (squat: r = 0.84, leg press: r = 0.90), whereas the root-mean-square errors (RMSE) were lower in the mediolateral (squat: 3.9 mm, leg press: 4.5 mm) than the anteroposterior (squat and leg press: 11.8 mm) direction. Vertical GRF was slightly overestimated by the insoles in leg press and RMSE were greater in leg press (8% of peak force) than in squat (6%). Overall, results were within the range of previous studies performed on gait. The strong agreement between insole and FP measurements indicates that insoles may replace FPs in field applications and biomechanical computations during resistance exercise, provided that the applied force is sufficient. 相似文献
57.
Joseph P. Royan 《Hydrobiologia》1976,51(3):209-212
Studies on the food and feeding habits of Leptestheriella maduraiensis Nayar & Nair have shown that the organisms are nonselective algal and detrital filter feeders. They utilise available food in almost similar proportions as in the overlying pond water and it is found from the present studies that the phytoplankton (Bacillariophyceae, Chlorophyceae and Cyanophyceae) form the major part of the gut (48.9%), followed by detritus (38.6%), zooplankton (11.1%) and miscellaneous items (1 .4%).Formed part of a thesis approved for the degree of Ph.D. of the Madurai University, 1973.Formed part of a thesis approved for the degree of Ph.D. of the Madurai University, 1973. 相似文献
58.
Herbaceous riparian buffers (CP 21 grass filter strips) are a widely used agricultural conservation practice in the United States for reducing nutrient, pesticide, and sediment loadings to agricultural streams. The ecological impacts of herbaceous riparian buffers on the channelized agricultural headwater streams that are common throughout the midwestern United States have not been evaluated. We sampled riparian habitat, geomorphology, instream habitat, water chemistry, fishes, and amphibians for 4 years from three channelized agricultural headwater streams without herbaceous riparian buffers and three channelized streams with herbaceous riparian buffers in central Ohio. Only seven of 55 response variables exhibited differences between buffer types. Riparian widths were greater in channelized headwater streams with herbaceous riparian buffers than streams without herbaceous riparian buffers. Percent insectivores and minnows were greater in channelized streams without herbaceous riparian buffers than streams with herbaceous riparian buffers. Percent clay, turbidity, specific conductance, and pH differed between buffer types only during one sampling period. No differences in geomorphology and amphibian communities occurred between buffer types. Our results suggest channelized agricultural headwater streams with and without herbaceous riparian buffers are similar physically, chemically, and biologically. Installation of herbaceous riparian buffers alone adjacent to channelized agricultural headwater streams in central Ohio and other parts of the midwestern United States may only provide limited environmental benefits for these stream ecosystems in the first 4-6 years after establishment. Alternative implementation designs combining the use of herbaceous riparian buffers with other practices capable of altering nutrient and pesticide loads, riparian hydrology, and instream habitat are needed. 相似文献
59.
60.