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121.
R. M. Honji A. M. Narcizo M. I. Borella E. Romagosa R. G. Moreira 《Fish physiology and biochemistry》2009,35(1):109-123
Fecundity and oocyte development in Salminus hilarii female brood stock were analyzed with the aim of investigating the impact of migration impediment on oogenesis. Histological
analyses of the ovaries were performed in adult females caught in two different environments—the Tietê River (natural) and
captivity—and the gonadossomatic index, oocyte diameter and fecundity determined. Five germ cell development stages (oogonium,
perinucleolar, cortical alveoli, vitellogenic, ripe) and two other structures (postovulatory follicles and atretic oocytes)
were observed in females caught in the river. Captive animals lacked the ripe oocytes and postovulatory follicles and had
a relatively higher number of atretic oocytes. Females in captivity are known to produce larger oocytes, and they release
fewer eggs in each spawn (absolute fecundity) when compared with animals that are able to migrate. Our results suggest that
the Tietê River is undergoing alterations which are being reflected in the reproductive performance of S. hilarii, mainly due to the presence of atretic oocytes in females caught in the river. The lack of postovulatory follicles and ripe
oocytes in captive animals reveals that migratory impediment negatively impacts final oocyte maturation. However, the stage
of maturation reached is adequate for ovulation induction with hormone manipulation. 相似文献
122.
Ana R. Linde Jorge I. Izquierdo Josino Costa Moreira Eva Garcia‐Vazquez 《水产资源保护:海洋与淡水生态系统》2008,18(6):891-895
- 1. Invasions are a main concern for conservationists. Identification of causes that raise or promote an invader's success is one of the first steps for preventing and/or fighting against invasions.
- 2. In the Brazilian River Paraiba do Sul, juveniles of invasive tilapia Oreochromis niloticus were detected associated with degraded habitats (mainly pollution from various sources). The relative abundance of juveniles of the competitor native species pearl cichlid Geophagus brasiliensis, morphologically and ecologically very similar, was negatively associated with habitat degradation.
- 3. A species‐specific molecular marker was employed to permit unambiguous identification of these small juveniles (2–3 cm long), which represent the most vulnerable life stage of both species.
- 4. It is suggested that adaptation to degraded habitats is one of the characteristics of invasive species, and consequently habitat conservation and restoration may help to prevent fish invasions.
123.
124.
SUMMARY An investigation of sheep flocks with unknown histories of fleece derangement, selected at random from the main sheep raising areas of New South Wales, showed that Psorergates ovis was present in 53 of the 177 flocks surveyed and In 162 of the 3495 sheep examined. Of the single causes of fleece derangement, the most prevalent was grass seed contamination (15.7%) followed by Infestation with sheep body lice, Bovicola ovis, (14.7%) and Infestation with Itch mite (7.8%). The prevalence of fleece derangement was significantly higher on sheep In which lice were the only ectoparasites found than on those In which Itch mites were the only ectoparasites present. The greatest prevalence of P ovis was In flocks In the Young, Yass, Mudgee and Tenterfield districts. In most affected flocks, more than one potential cause of fleece derangement was present. Itch mite Infestation was more prevalent in flocks that received no treatment for ectoparasites than in those that had been treated in the year preceding the survey. Our results did not support a commonly held belief among farmers that arsenical compounds control Infestations of Itch mites more effectively than other types of pesticides. There was no significant difference in prevalence of fleece derangement between flocks treated with different pesticide groups and those that received no treatment, but mean fleece derangement score was significantly lower in sheep treated with organophosphates than in untreated sheep. Infestations of lice were significantly more prevalent in sheep from flocks treated with synthetic pyrethroids than from those treated with organophosphates or those that received no treatment. 相似文献
125.
Modelling the impact of agricultural abandonment and wildfires on vertebrate diversity in Mediterranean Europe 总被引:1,自引:0,他引:1
Agricultural land abandonment, widespread in the Mediterranean, is leading to a recovery of scrubland and forests which are
replacing open habitats and increasing wildfire events. Using published data, we modelled the global and regional impact of
abandonment and wildfires on 554 species of terrestrial vertebrates occurring in Mediterranean Europe. For all groups except
amphibians, open habitats or farmland sustained higher species richness. Open habitats showed regional differences in their
conservation value, western areas being particularly important for birds and amphibians and eastern areas for reptiles. Scrublands
hosted fewer species than open habitats, farmland and forest, but sustained several endemic birds and mammals. The greater
species richness of forests was mostly due to species widespread in Europe. Wildfires promote scrubland expansion in detriment
of forest; because more species are associated to eastern forests, fire is predicted to affect more seriously this region.
Scrubland conservation value was found to be highest in the west, where fire might have a positive impact. Fire regime, however,
plays a crucial role. Although large fires have a negative impact, small-scale fires may favour biodiversity in abandoned
areas. Due to the intrinsic difficulty in managing abandoned land to preserve the original Mediterranean vertebrate diversity,
the best option to achieve this goal is the development of policies designed to make farmers and traditional farmland survive. 相似文献
126.
A Ortega-Pacheco JC Rodríguez-Buenfil JC Segura-Correa ME Bolio-Gonzalez M Jiménez-Coello C Linde Forsberg 《Reproduction in domestic animals》2006,41(5):429-437
The objective of this study was to estimate the prevalence of and risk factors for pathological conditions of the reproductive organs in stray dogs under tropical conditions. Three hundred and eighteen dogs were examined post-mortem in the period from 1 July 2002 to 30 June 2003. Before killing, a blood sample (from the cephalic vein) for testosterone assay was taken. Pathological conditions of the reproductive organs were found in 135 of the dogs (42.5%) and in 175 of the testes (64.8%). The most frequent pathologies found were testicular degeneration, cryptorchidism, testicular hypoplasia and testicular tumours (in 15.1%, 6.6%, 6.6% and 5.4% of the dogs and 15.1, 4.6, 6.0 and 3.5 of the testes, respectively). Transmissible venereal tumour (TVT) was seen in 5.4% of the dogs. Testicular degeneration was more common in old dogs and underweight dogs (p < 0.05). Testicular tumours were 14.3 times more common in cryptorchid dogs. Age was another important factor for the development of testicular tumours (p < 0.05). Lower levels of testosterone concentration (p < 0.05) were observed in dogs with advanced testicular degeneration (0.7 +/- 0.8 nM), dogs with hypoplastic testicles (0.8 +/- 0.9 nM) and dogs with one degenerated and one retained testis or with bilateral cryptorchidism (1.2 +/- 0.9 nM) compared to dogs with one or two normal testes (7.0 +/- 5.5 nM). Testicular volume and weight were significantly lower in degenerated, hypoplastic and retained testes compared with the contralateral normal testis. Some spermatogenic activity was found in three of the retained testes, producing oligozoospermic smears with a high percentage of sperm abnormalities. No comparable epidemiological data about male pathological conditions of the reproductive organs in the dog is available. The prevalence found in this study, yet, appears high. 相似文献
127.
M Abad JC Garcia DJ Sprecher G Cassar RM Friendship MM Buhr RN Kirkwood 《Reproduction in domestic animals》2007,42(4):418-422
In swine, the use of frozen-thawed (FT) sperm for artificial insemination (AI) is limited because of poor sow fertility, possibly associated with a post-thaw capacitation-like status resulting in fewer fully viable sperm. Sow fertility to AI with FT sperm may improve with deeper deposition of sperm within the female tract, insemination very close to ovulation, or reversal of cryocapacitation by seminal plasma (SP). We performed two experiments to examine these suggestions. In experiment 1, 122 multiparous Yorkshire sows received 600 IU equine chorionic gonadotrophin at weaning and 5 mg pLH 80 h later to control time of ovulation. The predicted time of ovulation (PTO) was 38 h after pLH injection. Thereafter, sows were assigned on the basis of parity to a single AI of FT sperm at 2 h before PTO, or at 12 h before PTO, or FT sperm supplemented with 10% SP at 12 h before PTO. Control sows received fresh semen at 12 h before PTO. All semen doses were adjusted to 3 x 10(9) live cells and deposited into the cervix. Experiment 2 employed 99 multiparous crossbred sows and repeated the treatments of experiment 1 except that all FT inseminations were intrauterine. In both experiments, farrowing rates were lower (p < 0.01) following FT inseminations with no effect of time of insemination or of supplemental SP. In experiment 1, litter size was smaller following FT insemination (p < 0.05), but no effect on litter size was evident in experiment 2. Supplemental SP had no effect on litter size in either experiment. The lack of effect of either SP or timing of FT insemination on sow fertility suggests that the non-lethal sperm cryoinjury affecting fertility involves more than just cryocapacitation. 相似文献
128.
Dermal and serological response against Pseudomonas aeruginosa in sheep bred for resistance and susceptibility to fleece-rot 总被引:1,自引:0,他引:1
Genetically select lines of Merino sheep have been bred at Trangie (NSW Agriculture and Fisheries) for resistance (R) or susceptibility (S) to fleece-rot and flystrike. It is believed that fleece characters are primarily responsible for the R or S phenotype. When transferred to the wetter coastal environment of Sydney, R and S sheep with no more than 6 weeks wool cover, continued to show significant differences in the incidence and severity of fleece-rot dermatitis. To test the hypothesis that these sheep might also exhibit differences in their local skin reactions and immune responsiveness, 3 intradermal injections of killed Pseudomonas aeruginosa were administered at monthly intervals. After primary intradermal challenge, R sheep had a higher incidence of skin induration and a stronger inflammatory response (increased induration diameter) than S sheep. Compared to S sheep, R sheep also developed higher levels of circulating antibodies against whole cell antigen and both inner and outer membrane proteins of P. aeruginosa. These responses were maintained in R sheep with each consecutive challenge while S sheep showed a decline in their immune responsiveness. Differences in antibody response against outer membrane proteins were also detected when antigenically naive sheep from each genetic line were sensitised by epicutaneous challenge with P. aeruginosa under experimental wetting conditions. Intradermal challenge of these animals 6 months later with outer membrane proteins, revealed a late maximum (72 h) in the development of induration diameters for R sheep while S animals showed maximal induration diameters by 24 h. However, there was no significant difference in induration response between 24 h and 72 h within each group of sheep.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
129.
130.
Roberto M. Junqueira Fabrício Rocha Maurílio A. Moreira Inar A. Castro 《Cereal Chemistry》2007,84(5):443-449
Soybean lipoxygenase addition in wheat bread doughs is widely used to improve the crumb color and rheology but little is known about the variability of the activity of lipoxygenase under diverse breadmaking conditions. Thus the objective of this study was to evaluate how soybean lipoxygenase can affect bleaching, volume, and sensory characteristics of French breads when proofing time and wheat flour strength varies. A 3-factor Box-Behnken design was used in this study containing one block and three independent variables or factors designated by exogenous lipoxygenase activity (x1 = 0–71 unit/μg of protein), wheat flour deformation energy (x2 = 231–258 × 10–4 J), and proofing time (x3 = 2–6 hr). Breads were randomly prepared and all assays were repeated three times. Specific volume (from 5.8 ± 0.4 to 9.9 ± 0.4 cm3/g), sensory quality (from 5.2 ± 0.8 to 8.3 ± 0.6), and yellow hue (from 12.6 ± 0.5 to 16.2 ± 0.3) significantly changed (P < 0.01) among the treatments. Specific volume of the breads increased with higher values of wheat flour strength and proofing time (ŷvs = 7.5 + 0.9 x2 + 1.2 x3 +0.5 x2x3). Sensory quality improved at higher values of wheat flour strength and shorter proofing time (ŷsq = 7.8 + 0.7 x2 – 0.2 x3 – 0.4 x22 – 0.6x32 + 0.5 x2x3), while lower and more desirable values of yellow hue were achieved at longer proofing time, higher activity of lipoxygenase, and using stronger wheat flours (ŷb = 13.7 – 1.2 x1 – 0.5 x2 – 0.2 x3 + 1.0 x12 – 0.3 x1x2). All regression models showed a good fitness to the experimental data (lack-of-fit P > 0.05) and the difference between predicted and observed values were also not significant (P < 0.05). Our results suggested that proofing time and wheat flour strength have a greater effect on volume and sensory quality of French breads than soybean lipoxygenase. However, the bleaching effect of this enzyme showed positive interaction with proofing time and wheat flour strength, suggesting its application even when strong wheat flours are used for the manufacture of French breads. 相似文献