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排序方式: 共有155条查询结果,搜索用时 15 毫秒
21.
Temara A. Aboutboul P. Warnau M. Jangoux M. Dubois Ph. 《Water, air, and soil pollution》1998,102(1-2):201-208
Lead uptake kinetics in the body compartments of Asterias rubens individuals exposed through sea water to different concentrations (5, 20, 50 µg Pb l-1) were studied during 30 days. Uptake kinetics were always best described by linear regressions. In every compartment, uptake rate increased significantly with the contaminating concentration. At a given concentration, the uptake rate of the central digestive tract was always significantly higher than that of the other compartments. After short-term exposures (50 µg Pb l-1, 8 days), fate of accumulated Pb was followed in asteroids kept in non-contaminated water during 20 days. The central digestive tract and the pyloric caeca lost Pb according to an inverse exponential trend and concentrations returned to initial values after 4 to 8 days. Pb concentrations in the body wall decreased linearly. Pb concentrations in the skeleton did not vary significantly. In the gonads, Pb concentrations kept on rising while exogenous Pb was no more supplied. Pb loss from the body wall and the digestive compartments could account for such endogenous source to the gonads. It is suggested that Pb accumulated in the gonads is expulsed later through spawning. According to the parameters of uptake and loss kinetics, the central digestive tract and the skeleton are proposed as complementary temporal bioindicators of Pb contamination. 相似文献
22.
By B. ZS. Kova CS M. Gauly G. Stranzinger 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》1999,116(3):235-242
The present study involved three male lamas ( Lama glama ). Mitotic preparations from fibroblast culture and an electron microscopic observation on the synaptonemal complexes (Scs) were reported. Special attention was given to the morphology and behaviour of the chromosomes at the zygotene and pachytene substages of prophase I in primary spermatocytes from lamas. Analysis of mitotic preparations show diploid and triploid cells, with a relatively high frequency of polyploidy. Analyses of synaptonemal complexes in primary spermatocytes were carried out on 89 cells. Pairing abnormalities were only recorded in an average of 63% of the cells of the animal Tabasco. The other two animals were normal. The photographed cells give an upper limit estimate of the existing abnormalities, as there was a deliberate tendency towards selecting abnormal cells for photography. The presence of degenerating primary spermatocytes in SC preparations as well as in testicular sections, and the absence of spermatozoa in ejaculates confirm the chromosomally derived male sterility of one animal. 相似文献
23.
Elena Dubois Gill Santiago Schaerer Brice Dupuis 《European journal of plant pathology / European Foundation for Plant Pathology》2014,140(2):317-327
Stem rot symptoms caused by pectinolytic bacteria of Genus Pectobacterium and Genus Dickeya, which are commonly referred to as blackleg, strongly impact the quality of seed potato production in most European countries. Several biotic and abiotic factors, such as cultivar susceptibility, isolate aggressiveness, mother tuber infection density and a wide range of soil-related and climatic factors have been identified in the literature as having an effect on blackleg development. The aim of this study was to identify which biotic and/or abiotic factors are most critical to the development of blackleg in the field. In Switzerland, the predominant species have belonged to Genus Dickeya as far back as 1992, which is why this study only investigates blackleg symptoms induced by Dickeya isolates. Seven field trials, in which inoculated tubers were planted, were conducted during a 3-year period and the number of blackleg-diseased plants was counted. Multiple regression analysis was used in order to determine the factors that had the greatest impact on two different variables: (i) periods between emergence of the plant and disease outbreak and (ii) overall blackleg incidence throughout the growing season. The results of this analysis have revealed that environmental factors, such as evapotranspiration and soil moisture, explain about half of the variability in the number of days before disease outbreak, and the total number of diseased plants is widely dependent upon cultivar susceptibility and isolate aggressiveness. 相似文献
24.
Objective To determine the prevalence of mastitis pathogens in high‐producing intensive dairy herds in New South Wales. Design Field survey. Procedure Milk samples from the mastitis‐affected quarter were collected from cows on five high‐producing dairy farms in NSW. The 820 samples were cultured using standard microbiological culture techniques. Results Bacteria or fungi were isolated from 83.3% of samples (683/820). More than two colony types were isolated from 16.7% of samples (137/820), two types from 6.6% (54/820), and one type from 52.3% (429/820). No bacteria were isolated from 24.4% (200/820) of the primary cultures, but enrichment cultures of these samples yielded single colony type bacterial isolates from 36.5% (73/200) of samples. Environmental pathogens, including coliforms, environmental Streptococcus and Staphylococcus spp., made up 91% (555/610) of isolates and accounted for 33.6% (205/610), 41.6% (254/610) and 15.7% (96/610), respectively, of isolates. Escherichia coli accounted for 76.1% (156/205) of the coliform isolates, Streptococcus uberis and Streptococcus dysgalactiae accounted for 32.3% (82/254) and 28.0% (71/254), respectively, of the environmental streptococcal isolates. Contagious pathogens were uncommon, comprising only 2.5% (15/610) of the total isolates. Conclusion The incidence and causes of mastitis are largely influenced by farm management. The relatively high prevalence of coliform mastitis in the intensive high‐producing herds in this survey contrasts with the low incidence reported in surveys of pasture‐based herds in Victoria. If the Australian dairy industry continues its current trend of intensification, coliform intra‐mammary infections may emerge as an increasingly important cause of mastitis. 相似文献
25.
Surgical resection of a dysgerminoma in a mare 总被引:1,自引:1,他引:0
A mare was referred for further evaluation of a mass found in the left caudal abdomen during a routine postpartum reproductive palpation. The mare was clinically normal with no history of health problems. Ultrasonographic examination of the mass confirmed its presence, but the origin of the mass could not be accurately determined. Routine haematology and serum biochemistry results were within normal limits. The mare was initially treated conservatively with antibiotics, but the mass continued to increase in size, so it was surgically excised. The mass involved the left ovary. The mare showed transient abdominal pain after surgery, but developed no other complications and was in foal 7 months later. On histology, the mass was diagnosed as a dysgerminoma, a rare ovarian tumour of germ cell origin. 相似文献
26.
Participation of phosphofructokinase,malate dehydrogenase and isocitrate dehydrogenase in capacitation and acrosome reaction of boar spermatozoa 下载免费PDF全文
E Breininger D Dubois VE Pereyra PC Rodriguez MM Satorre PD Cetica 《Reproduction in domestic animals》2017,52(5):731-740
The aim of this work was to determine the enzymatic activity of phosphofructokinase (PFK), malate dehydrogenase (MDH) and isocitrate dehydrogenase (IDH) in boar spermatozoa and study their participation in bicarbonate‐induced capacitation and follicular fluid‐induced acrosome reaction. Enzymatic activity of these enzymes was determined spectrophotometrically in extracts of boar spermatozoa. Sperm suspensions were incubated in the presence of bicarbonate (40 mM), a well‐known capacitation inducer, or follicular fluid (30%), as an acrosome reaction inducer, and different concentrations of oxoglutarate, oxalomalate and hydroxymalonate, inhibitors of PFK, IDH and MDH, respectively. Capacitation percentages were determined by the fluorescence technique of chlortetracycline (CTC), and true acrosome reaction was determined by trypan blue and differential–interferential contrast, optical microscopy. The activity of PFK in boar spermatozoa enzymatic extracts was 1.70 ± 0.19 U/1010 spermatozoa, the activity of NAD‐ and NADP‐dependent IDH was 0.111 ± 0.005 U/1010 and 2.22 ± 0.14 U/1010 spermatozoa, respectively, and the activity of MDH was 4.24 ± 0.38 U/1010 spermatozoa. The addition of the specific inhibitors of these enzymes prevented sperm capacitation and decreased sperm motility during capacitation and inhibited the acrosome reaction (AR), without affecting the sperm motility during this process. Our results demonstrate the participation of PFK, IDH and MDH in bicarbonate‐induced capacitation and follicular fluid‐induced acrosome reaction in boar spermatozoa, contributing to elucidate the mechanisms that produce energy necessary for these processes in porcine spermatozoa. 相似文献
27.
C. Desvignes M. Chaurand M. Dubois A. Sadoudi J. Abecassis V. Lullien-Pellerin 《Journal of Cereal Science》2008
Ozone treatment (10 g/kg) of common wheat grains with a new patented process, Oxygreen®, used before milling was found to significantly reduce (by 10–20%) the required energy at breaking stage whatever the grain hardness and without changes in the flour yield. Detailed study of each of the milling steps undertaken on a hard type cultivar showed that both the breaking and the reduction energy were decreased. Reduction of the coarse bran yield was also observed concomitantly with an increase in the yield of white shorts. Biochemical characterization of the milling fractions pointed out changes in technological flour properties as starch damage reduction, aleurone content enrichment and increase of insoluble glutenin polymers. Measurement of wheat grain tissue mechanical properties showed that ozone treatment leads to reduction of the aleurone layer extensibility and affects the local endosperm resistance to rupture. These data as well as the direct effect of ozone oxidation on biochemical compounds could explain the observed changes in milling energy, bran and shorts yield and flour composition. 相似文献
28.
Growth and yield characteristics of two different clones of banana plants (Musa AAA cv. Grande naine) originating from four months old embryogenic cell suspensions were studied. These characteristics were
compared with those plants produced by the conventional in vitro budding multiplication method. Two types of variants were observed during the acclimatization phase among 500 embryogenic
cell suspension derived plants. The first type related to banana plants with `variegated or deformed leaves' were also observed
in in vitro budding derived plants. The second type concerned `fasciated-leafed' plants. During the field growth, these two variant types
produced plants morphologically similar to the other plants. Thus, none of the cell suspension derived plants exhibited off-type
traits in the field. A Fisher block model was used to compare the field performances of the two clones produced through the
two in vitro propagation techniques. The analysis of variance showed that there were no significant differences between the plants produced
by either micropropagation techniques for the plant height and circumference, the length of the reference leaf, the number
of nodal clusters of the inflorescence and of fruits, the bunch weight, the period of time between planting and flowering,
and between planting and harvesting. This study showed that banana plants with an agronomical behaviour similar to those produced
by the conventional in vitro budding method could be regenerated from embryogenic cell suspension.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
29.
B. Hijazi F. Cointault J. Dubois S. Coudert J. Vangeyte J. Pieters M. Paindavoine 《Precision Agriculture》2010,11(6):684-702
Excessive fertiliser use has been a main contributor to the increasing environmental imbalance observed in the past 20 years.
Better accuracy in spreading would limit excess fertiliser loss into the environment. Increased accuracy begins by understanding
the fertiliser spreading process from the vane to the soil. Our work concentrates on the use of centrifugal spreaders, as
these are most commonly used in Europe. Progress in imaging devices and image processing has resulted in the availability
of new technologies to use when describing the behaviour of fertiliser granules during ejection from centrifugal spreaders.
Fertiliser deposition on the soil can be predicted using a ballistic flight model, but this requires determination of the
velocities and the directions of the granules when they leave the spinning disc. This paper presents improvements to the high
speed imaging system that we had previously developed, i.e. enhancements to the illumination and the image processing. The
illumination of the previous system, which used many separate flashes, did not give consistent illumination. We have improved
it by using a stroboscope with power-LEDs, located at 1 m height around the digital camera and controlled by a Field-programmable
gate array (FPGA) card. The image processing has been improved by development of a multi-phase method based on a cross-correlation
algorithm. We have compared the cross-correlation method to the Markov Random Fields (MRF) method previously implemented.
These tests, based on multi-exposure images, revealed that cross-correlation method gives more accurate results than the MRF
technique, with guaranteed sub-pixel accuracy. Knowing that an error of one pixel can lead to a prediction error between 200
and 500 mm on the ground, the latter method gives an accuracy range between 0.1 and 0.4 pixels, whereas the MRFs technique
is limited to 3 and 9 pixels for the vertical and horizontal components of the velocities, respectively. The sub-pixel accuracy
of the new method was proven by applying it on simulated images with known displacements between the grains. By using a realistic
spreading model, the simulated images are similar to those obtained with a high speed imaging system. This sub-pixel accuracy
now makes it possible to decrease the resolution of the camera to that of a classical high-speed camera. These improvements
have created an affordable and durable system appropriate for installation on a spreader. Farmers could use this system to
both calibrate the spreader and verify the fertiliser distribution on the ground. 相似文献
30.