全文获取类型
收费全文 | 6672篇 |
免费 | 276篇 |
国内免费 | 8篇 |
专业分类
林业 | 231篇 |
农学 | 345篇 |
基础科学 | 82篇 |
833篇 | |
综合类 | 360篇 |
农作物 | 247篇 |
水产渔业 | 197篇 |
畜牧兽医 | 3690篇 |
园艺 | 107篇 |
植物保护 | 864篇 |
出版年
2023年 | 30篇 |
2022年 | 41篇 |
2021年 | 56篇 |
2020年 | 80篇 |
2019年 | 86篇 |
2018年 | 101篇 |
2017年 | 101篇 |
2016年 | 112篇 |
2015年 | 93篇 |
2014年 | 129篇 |
2013年 | 489篇 |
2012年 | 296篇 |
2011年 | 348篇 |
2010年 | 171篇 |
2009年 | 172篇 |
2008年 | 332篇 |
2007年 | 320篇 |
2006年 | 272篇 |
2005年 | 272篇 |
2004年 | 284篇 |
2003年 | 253篇 |
2002年 | 247篇 |
2001年 | 234篇 |
2000年 | 215篇 |
1999年 | 196篇 |
1998年 | 53篇 |
1997年 | 53篇 |
1996年 | 55篇 |
1995年 | 62篇 |
1994年 | 39篇 |
1993年 | 45篇 |
1992年 | 105篇 |
1991年 | 117篇 |
1990年 | 133篇 |
1989年 | 112篇 |
1988年 | 100篇 |
1987年 | 84篇 |
1986年 | 67篇 |
1985年 | 73篇 |
1984年 | 66篇 |
1983年 | 46篇 |
1982年 | 31篇 |
1981年 | 41篇 |
1980年 | 45篇 |
1979年 | 47篇 |
1978年 | 26篇 |
1975年 | 26篇 |
1973年 | 26篇 |
1972年 | 35篇 |
1971年 | 33篇 |
排序方式: 共有6956条查询结果,搜索用时 13 毫秒
51.
A two-month-old female Tibetan terrier was re-presented with an incomplete closure of the patent ductus arteriosus. Following a second attempt to close the shunt by coil embolisation, arterial embolisation occurred. The successful removal of the embolised coil is described. 相似文献
52.
53.
54.
Kovalik M Thoday KL Evans H van den Broek AH Mellanby RJ 《Veterinary journal (London, England : 1997)》2012,192(2):212-216
The aim of this study was to assess the effects of a standard therapeutic protocol of prednisolone (Pred) on glucose homeostasis in atopic dogs and compare it with previously published data for ciclosporin A (CsA). The central aim of the study was to assess and compare the effects of standard therapeutic protocols of prednisolone (Pred) and ciclosporin A (CsA) on glucose homeostasis in dogs with atopic dermatitis (CAD). Both treatments significantly reduced the physical signs of CAD, as determined by the canine atopic dermatitis extent and severity index version 3 (CADESI-03) and the Edinburgh Pruritus Scale (EPS). Post-treatment plasma glucose concentrations were not significantly different in the two groups, but serum insulin concentrations were significantly higher following Pred therapy (P<0.05). Serum fructosamine concentrations were not significantly different pre- and post-treatment with Pred, although previous studies had shown that CsA treatment increased fructosamine concentrations (P<0.005). The two treatment groups were recruited in a similar timeframe, were numerically matched and there were no differences in CADESI-03 and EPS scores between the CsA and Pred groups either before or after treatment. Thus, both CsA and Pred treatment were associated with mild disturbances in glucose metabolism, but only CsA therapy resulted in a significant increase in fructosamine concentrations. This information may be relevant to clinicians when considering therapeutic options for dogs with atopic dermatitis which already have impaired glucose homeostasis. 相似文献
55.
Hormonal responses to acute exercise, training and overtraining. A review with emphasis on the horse 总被引:1,自引:0,他引:1
de Graaf-Roelfsema E Keizer HA van Breda E Wijnberg ID van der Kolk JH 《The Veterinary quarterly》2007,29(3):82-101
Overtraining is an imbalance between training and recovery leading to symptoms associated with a neuroendocrine dysbalance called the overtraining syndrome, a disease characterized by behavioral, emotional and physical symptoms similar with depression. Although the prevalence of overtraining is high in human and equine athletes, at present no sensitive and specific test is available to prevent or diagnose overtraining. Nowadays, it is believed that combination of different (hormonal) parameters appear to be the best indicators of overtraining. Therefore, this review provides a summary of previous literature examining the response of the hypothalamic-pituitary-adrenal (HPA) axis and the growth hormone-insulin-like growth factor-I (GH-IGF-I) axis to acute and chronic exercise as well as overtraining in humans and horses. The exercise induced hormonal responses seem to be equal for the equine as well as the human athlete, which makes comparisons possible. Repeated bouts of exercise are suggested to provide a way to detect subtle changes in hormonal responses in the individual athlete, which may make them an important tool in detecting early overtraining. This should be combined with corticotropin releasing hormone (CRH) stimulation tests and basal ACTH and GH pulsatility determination. Further research is needed to establish the correct training intensity and rest period for the exercise test in equines. 相似文献
56.
van der Harst MR DeGroot J Kiers GH Brama PA van de Lest CH van Weeren PR 《American journal of veterinary research》2005,66(7):1238-1246
OBJECTIVE: To assess whether site-related changes in biochemical composition are present in the cartilage and subchondral and trabecular bone of the metacarpophalangeal joint of horses with early osteoarthritis. SAMPLE POPULATION: Right metacarpophalangeal joints from 59 mature warmblood horses. PROCEDURE: Biochemical data (cross-link, amino acid, DNA, and ash contents; denatured collagen and glycosaminoglycan [GAG] concentrations; bone mineral density; and mineral composition) were obtained from 2 differently loaded sites of phalanx I cartilage and subchondral and trabecular bone samples; data were compared with previously published values from nonosteoarthritic equine joints. RESULTS: Compared with findings in nonosteoarthritic joints, GAG concentration was lower in cartilage from osteoarthritic joints and there was a loss of site differences in cellularity and lysylpyridinoline (LP) cross-link content. In subchondral bone, LP cross-link content was decreased overall and there was a loss of site differences in osteoarthritic joints; ash content was higher in the osteoarthritic joints. Hydroxyproline content in trabecular bone from osteoarthritic joints was greater than that in nonosteoarthritic trabecular bone. In all 3 layers and at both sites, the linear increase of the pentosidine cross-link content with age had diminished or was not apparent in the horses with osteoarthritic joints. CONCLUSIONS AND CLINICAL RELEVANCE: In equine metacarpophalangeal joints with early osteoarthritis, distinct biochemical changes were detected in the cartilage and subchondral and trabecular bone. The dissimilarity in response of the different tissues and differences between the sites that are affected may be related to differences in biomechanical loading and transmission and dissipation of force. 相似文献
57.
The effect of clenbuterol on the incidence of abomasal lesions in veal calves was studied in two fattening units. Some of the calves in each unit were treated with 1.6 micrograms clenbuterol/kg bodyweight/day from the seventh until the 23rd week of the fattening period. In one unit the calves were fed milk replacer only and 176 of the 236 calves were treated with clenbuterol. In the other unit the calves were fed roughage pellets in addition to milk replacer and 92 of the 194 calves were treated with clenbuterol. Only in the second unit did the calves treated with clenbuterol have significantly fewer abomasal lesions. 相似文献
58.
Brommer H Sloet van Oldruitenborgh-Oosterbaan MM Kessels B 《The Veterinary quarterly》2001,23(2):92-95
Reference values for haematological and blood biochemical variables may vary per breed and are influenced by age and, to a certain extent, by rearing conditions. To investigate the influence of age and rearing conditions, these variables were measured in Dutch Warmblood foals from birth to 5 months of age. The foals were divided into three groups with different exercise regimens: 14 foals got boxrest with no exercise; 14 foals were kept in comparable boxes, but received daily exercise; and 15 foals were maintained on pasture with free exercise. Blood samples were collected each month and 36 haematological and biochemical variables were measured. The influence of age and rearing conditions was statistically evaluated. Significant age effects were found for all variables with the exception of band-shaped leucocytes, eosinophilic leucocytes, basophilic leucocytes, monocytes, platelets, pCO2, and sodium, potassium, calcium, magnesium, creatinine and creatine phosphokinase levels. Rearing conditions appeared to influence the haemoglobin, packed cell volume, pH, base excess, bicarbonate, chloride, urea, and alkaline phosphatase values. Most age-related differences can be explained by growth and differentiation-related processes that are specific for young animals. Differences due to the different rearing conditions can partly be explained by the higher metabolism and greater maturation of tissues in foals maintained on pasture with free exercise. Some other differences were minor and were probably of no clinical relevance. The conclusion is that haematological and blood biochemical variables in the Dutch Warmblood foal mainly depend on age, thus warranting the use of specific age-related reference values for foals of this breed. 相似文献
59.
60.
J. Kirpensteijn R.J. Maarschalkerweerd I. van der Gaag H.S. Kooistra F.J. van Sluijs 《The Veterinary quarterly》2013,33(2):67-70
Summary The macroscopic and histological appearance of jejunal antimesenteric incisions approximated with two different absorbable suture materials (monofilament versus multifilament) and three closure techniques (appositional single layer, crushing single layer, and double layer) were compared in healthy dogs at 14 or 28 days, postoperatively. No significant differences between the two suture materials were observed for most of the macroscopic or histological variables. However, the monofilament suture material caused significantly more fibrous tissue reaction in the muscular layer of the jejunum than did the multifilament suture material. Of the three enterotomy closure techniques used in this study, the appositional single‐layer method proved to be the best. The double‐layer closure method caused a significant decrease in the incisional circumference, the relative circumference, and volume of the jejunum, and a significant increase in jejunal wall thickness. Our findings suggest that canine jejunal enterotomy incisions can be closed using an appositional suture pattern with relatively rapidly absorbable monofilament suture material. The use of double‐layer suture patterns for closure of jejunal enterotomy incisions should be avoided because the size of the intestinal lumen may be reduced. 相似文献