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121.
F. E. Hinkle S. A. Johnson K. T. Selberg M. F. Barrett 《Equine Veterinary Education》2020,32(12):664-672
A normal variant is an atypical finding present in a percentage of the population that generally has no clinical significance and is considered within the spectrum of normal findings. Normal variants are recognised upon gross anatomical dissection and also observed radiographically. Understanding the range of normal variants is essential for proper radiographical interpretation. This ensures that these variants are not mistaken for pathological lesions and helps avoid radiographical misdiagnosis. Common sites of normal anatomical variation in the foot, pastern, carpus, tarsus, elbow, shoulder and axial skeleton are reviewed. 相似文献
122.
Total organism content of L-thyroxine (T4) and triiodo-L-thyronine (T3) were measured in the early developmental stages of a stock of Lake Ontario coho salmon from the egg to the yolk absorption
stage. Whole organism T4 levels were constant between the egg and pre-hatch embryo stages, but fell progressively during yolk absorption. T3 levels were low from egg to eye-pigment appearance, but then increased prior to hatch and fell again during the post-hatch
yolk absorption period.
When expressed as ng/tissue, T4 content of the body compartment rose progressively between days 67 and 87 post-fertilization, whilst T4 content of the yolk compartment fell progressively during the same period; the pattern was not evident for tissue T3 content. When expressed as ng/g dry weight of tissue, the inverse relationship was found for T4, and T3 content of the body and yolk compartments decreased progressively and increased progressively, respectively during the same
period, suggesting that thyroid hormones were selectively retained in the yolk compartment.
Intensely “immunostained” (using anti-human β-TSH antibody) thyrotropic cells were present in small numbers in the pars distalis
of the embryonic pituitary at the eye-pigment appearance stage, and the numbers increased markedly until the pre-hatch period.
Administration of either bovine thyrotropic hormone (bTSH) or ovine growth hormone (oGH) had no effect on thyroid hormone
content of larvae challenged during the yolk absorption period, suggesting that the thyroid tissue was not responsive to exogenous
bTSH challenge at this time, and that oGH-sensitive 5′-monodeiodination was either not present or at levels that were too
low to cause an elevation in total T3 content, or that the substrate levels were insufficient to permit a measureable increase in whole body T3 content. 相似文献
123.
A three-dimensional finite solid element model for Japanese traditional post-and-beam connections was developed using the
wood foundation method, which employed the concept of a beam on a nonlinear foundation. The wood foundation in the model was
a three-dimensionally prescribed zone surrounding a nail shank in order to address the intricate wood crushing behavior induced
by nail slip. Material models for the wood members and the foundation were developed based on the transversely isotropic plasticity
from the software package ANSYS. The Japanese post-and-beam connection modeled was a ten-nail multiple connection with a mortise
and tenon joint and is called the CPT (Corner Plate, T-shaped) connection. Details of the model development are presented.
As a feasibility study, blind predictions of the model were compared with available connection test data and showed good results
for predicting the progress of the load-deformation relations in three dimensions. However, the limitation of the model was
found in simulating fracture failures such as wood splitting or nail tear-out from the wood. Model applications and the need
for model improvement are discussed. 相似文献
124.
Three colorimetric reagents for the determination of formaldehyde, the Nash reagent (ammonia plus acetylacetone), Purpald (4-amino-3-hydrazino-5-mercapto-1,2,4-triazole), and N-methylbenzothiazolinone-2-hydrazone (MBTH), were compared for the determination of methanol when used in conjunction with alcohol oxidase. The combination of alcohol oxidase plus the commonly used Nash reagent was specific for methanol versus ethanol, but had the lowest sensitivity of the three reagents tested. Substituting Purpald for the Nash reagent increased the sensitivity 3-fold while still maintaining a high (59-fold) selectivity for methanol versus ethanol. Using MBTH increased the sensitivity still further, but with a loss of the selectivity toward methanol. Since MBTH reacted with aldehydes under neutral conditions, it could be included along with the alcohol oxidase to act as an aldehyde trap. This prevented further oxidation reactions by alcohol oxidase and allowed for extended incubations. A procedure for assaying low levels of pectin methylesterase activity that relies on this trapping ability is described. In addition, alcohol oxidase plus Purpald is shown to be a simple and sensitive way to measure the methanol released from plant material following the thermal activation of endogenous pectin methylesterase. 相似文献
125.
126.
Suzanne W. Barrett 《Biological conservation》1980,18(3):209-235
Amazonian environments are being disrupted and their animal and plant species endangered as a result of intense development of resources throughout the region. Current conservation measures include several national parks and reserves and legislation for the protection of wildlife. The majority of the parks and reserves are located on the periphery of the Amazon region and most of the diversity of Amazonian communities is not at present protected. Legislation for wildlife protection is poorly enforced and there is inadequate information on the distribution and status of threatened species. Conservation efforts are being stimulated by an Intergovernmental Committee for the Protection and Management of the Amazon Flora and Fauna. In Brazil, an extensive planning programme is underway for the establishment of a network of parks and reserves in the Amazon region. This paper reviews conservation measures and plans in Amazonia and provides some recommendations for future conservation strategies. 相似文献
127.
The amyloid precursor protein has a flexible transmembrane domain and binds cholesterol 总被引:1,自引:0,他引:1
Barrett PJ Song Y Van Horn WD Hustedt EJ Schafer JM Hadziselimovic A Beel AJ Sanders CR 《Science (New York, N.Y.)》2012,336(6085):1168-1171
C99 is the transmembrane carboxyl-terminal domain of the amyloid precursor protein that is cleaved by γ-secretase to release the amyloid-β polypeptides, which are associated with Alzheimer's disease. Nuclear magnetic resonance and electron paramagnetic resonance spectroscopy show that the extracellular amino terminus of C99 includes a surface-embedded "N-helix" followed by a short "N-loop" connecting to the transmembrane domain (TMD). The TMD is a flexibly curved α helix, making it well suited for processive cleavage by γ-secretase. Titration of C99 reveals a binding site for cholesterol, providing mechanistic insight into how cholesterol promotes amyloidogenesis. Membrane-buried GXXXG motifs (G, Gly; X, any amino acid), which have an established role in oligomerization, were also shown to play a key role in cholesterol binding. The structure and cholesterol binding properties of C99 may aid in the design of Alzheimer's therapeutics. 相似文献
128.
James O’Shaughnessy Bernadette Earley John F. Mee Michael L. Doherty Paul Crosson Damien Barrett Theo de Waal 《Irish veterinary journal》2015,68(1)
Background
With concerns over the development of anthelmintic resistance in cattle nematode populations, we must re-examine our approach to nematode control in cattle. Targeted selective treatments (TST), whereby individual animals are treated instead of entire groups, are being investigated as an alternative. The study objective was to determine if anthelmintic usage could be reduced using a TST-based approach to nematode control in spring-born suckler beef cattle over their first and second grazing seasons (SGS) without affecting performance. In the first grazing season (FGS), 99 calves with an initial mean (s.d.) calf age and live weight on day 0 (June 28th 2012) of 107 (23.1) days and 160 (32.5) kg, respectively, were used. The study commenced on day 0 when calves were randomised and allocated to one of two treatments; 1), standard treatment (control) and 2), TST. Control calves were treated subcutaneously with ivermectin on days 0, 41 and 82 in the FGS. All calves were treated with ivermectin on day 124 and housed on day 133. In the SGS, only heifer calves from the FGS were used and control heifers were treated with ivermectin on day 393. Animals were weighed, blood and faecal sampled every three weeks. The TST animals were treated with ivermectin if thresholds based on a combination of plasma pepsinogen concentrations, faecal egg count and/or the presence of Dictyocaulus viviparus larvae in faeces (FGS only) were reached.Results
No TST calves reached the treatment threshold criteria in the FGS. The FGS average daily live weight gain (ADG ± s.e.m.) for control and TST group calves was 0.89 ± 0.02 kg and 0.94 ± 0.02 kg day−1, respectively (P = 0.17). In the SGS, all heifers were treated with ivermectin on day 431 due to clinical signs of respiratory disease. The ADG for control and TST heifers from turnout on day 321 to day 431 was 0.90 ± 0.04 and 0.80 ± 0.04 kg day−1, respectively (P = 0.03).Conclusions
Spring-born FGS suckler beef calves require minimal anthelmintic treatment to maintain performance. In contrast, clinical parasitic disease may develop in the SGS unless appropriate anthelmintic treatment is provided. 相似文献129.
130.
The pathogenicity for sheep and goats of the virus strain that caused acute rinderpest in cattle and domestic buffalo in Sri Lanka after an interval of over 40 years has been examined. The results show that it can cause overt clinical disease in goats, but only mild or unapparent infection in sheep. The disease was transmitted from infected sheep to in-contact susceptible sheep and calves. 相似文献