首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   188篇
  免费   10篇
林业   6篇
农学   4篇
基础科学   1篇
  26篇
综合类   9篇
农作物   9篇
水产渔业   9篇
畜牧兽医   122篇
园艺   6篇
植物保护   6篇
  2023年   1篇
  2022年   1篇
  2021年   2篇
  2019年   4篇
  2018年   6篇
  2017年   4篇
  2016年   5篇
  2015年   7篇
  2014年   14篇
  2013年   14篇
  2012年   17篇
  2011年   16篇
  2010年   6篇
  2009年   5篇
  2008年   14篇
  2007年   14篇
  2006年   8篇
  2005年   5篇
  2004年   9篇
  2003年   9篇
  2002年   5篇
  2001年   1篇
  2000年   2篇
  1998年   1篇
  1996年   1篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   3篇
  1980年   2篇
  1979年   2篇
  1974年   2篇
  1973年   4篇
  1972年   1篇
  1971年   1篇
  1970年   3篇
排序方式: 共有198条查询结果,搜索用时 31 毫秒
111.
112.
113.
A 30-year-old Standardbred stallion was examined for unilateral scrotal swelling. Physical and ultrasound examinations revealed a painless enlarged left testis with a non-homogeneous echogenicity, when compared with the controlateral testis. The stallion underwent left unilateral orchiectomy. Grossly, the excised testis was irregularly enlarged (12 x 9 x 9 cm; weight: 530 g) and firm. The sections showed that testicular parenchyma was replaced by a lobulated, greyish-white mass, which involved the epididymal head. At microscopy, a dual Leydig and Sertoli cell tumour component could be seen. Neoplastic Sertoli cells were prevalent and presented pleomorphic cells, mitotic figures and occasional vascular invasion. Tumour patterns showed tubular and solid areas, cord-like or diffuse in appearance, among which newly formed Leydig cell nests and low-density fibrillar bundles were interposed. Immunohistochemically, a weak to moderate immunostaining for vimentin, AE(1)/AE(3) cytokeratin, alpha-1-antitrypsin and CD99 antigens was found in the growing Sertoli cells, whose nuclear MIB-1 labelling index scored 13 +/- 2%. The Leydig tumour cells, on the other hand, displayed a moderate to strong positivity for alpha-inhibin, vimentin, AE(1)/AE(3) cytokeratin, neurone-specific enolase and CD99. On the basis of these findings, a diagnosis of malignant mixed sex cord-stromal tumour was made.  相似文献   
114.
Two adult horses with progressive neurologic signs were examined clinically and at necropsy. Both horses had signs of progressive ataxia and weakness, clinically diagnosed as spinal cord in origin. Differential diagnoses for cervical spinal ataxia in horses included cervical vertebral malformation, equine degenerative myeloencephalopathy, equine herpes-virus-I myeloencephalopathy, and equine protozoal myeloencephalopathy. Necropsy findings in both horses were similar and consisted of a large hematoma in the fourth ventricle, with upward compression of the cerebellum and downward compression of the pons and rostral portion of the medulla.  相似文献   
115.
Immunostimulants represent a modern and promising tool in aquaculture, enhancing the resistance of cultured fish to disease and stress. This study investigated the effect of a combination of dietary glucans, alpha-tocopherol and ascorbic acid on the innate immune response of cultured sea bass (Dicentrarchus labrax). After 5 weeks of adaptation on a commercial diet containing 100 p.p.m. ascorbic acid and 200 p.p.m. alpha-tocopherol, sea bass were switched to a diet supplemented with 2% beta-1.3/beta-1.6 glucans and ascorbic acid and alpha-tocopherol at 500 p.p.m. The supplemented diet was given at 2% of body weight per day over a 2-week period, every 3 months. Plasma lysozyme concentration, content and distribution of major plasma proteins and complement activity were measured prior to feeding the supplemented diet and after 40 weeks. Alternative pathways of complement activation and lysozyme activity were both significantly enhanced in fish fed on glucans and elevated doses of vitamins. No significant differences were observed in protein content or in albumin/globulin ratio. Compared to lysozyme activity, which showed marked individual variation, complement-mediated haemolytic activity has been shown to be a more reliable indicator of sea bass immunocompetence. Further studies are in progress to clarify the effect of each dietary component on the innate immune response and disease resistance.  相似文献   
116.
Veterinary Research Communications - The limping syndrome is occasionally reported during acute feline calicivirus (FCV) infections or as consequence of vaccination. In this retrospective study,...  相似文献   
117.
118.
A study of nutrient distribution in the flowering stem of proteas was carried out in commercial protea plantations of each of the cultivars ‘Scarlett Ribbon’, ‘High Gold’, ‘Veldfire’, and ‘Sunrise’ of Leucospermum cordifolium, and of the species L. patersonii located in a subtropical zone (La Palma Island, Canarian Archipelago). Flowering stems were cut into different parts: flower bud, leaves from half proximal stem to the flower bud, leaves from half distal stem to the flower bud, half proximal stem to the flower bud, and half distal stem to the flower bud. Nutrient content of the different parts of the flowering stems of the cultivar and the species gave significant differences in some cases, depending on the nutrient and the cultivar. Occasional dissimilarities among the levels of nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), sodium (Na), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) were determined in comparisons among half proximal stems and half distal stems, independent of the cultivar. The same trend was observed when nutrient contents of the leaves from the half distal and the half proximal stems were compared. Phosphorus exhibited the lowest concentrations of all macronutrients in the different organs. Flower buds presented the smallest levels of macro-and micronutrients, while the leaves of the half distal and half proximal stems showed the highest values. The influence of nutrients of leaves from the half proximal stems on the stems length varied among cultivars.  相似文献   
119.
This research aimed to investigate erythrodiol, uvaol, oleanolic acid, and maslinic acid scavenging capacities and their effects on cytotoxicity, cell proliferation, cell cycle, apoptosis, reactive oxygen species (ROS) level, and oxidative DNA damage on human MCF-7 breast cancer cell line. The results showed that erythrodiol, uvaol, and oleanolic acid have a significant cytotoxic effect and inhibit proliferation in a dose- and time-dependent manner. At 100 μM, erythrodiol growth inhibition occurred through apoptosis, with the observation of important ROS production and DNA damage, whereas uvaol and oleanolic acid growth inhibition involved cell cycle arrest. Moreover, although all tested triterpenes did not show free radical scavenging activity using ABTS and DPPH assays, they protected against oxidative DNA damage at the concentration 10 μM. Uvaol and oleanolic and maslinic acids, tested at 10 and 100 μM, also reduced intracellular ROS level and prevented H(2)O(2)-induced oxidative injury. Overall, the results suggest that tested triterpenes may have the potential to provide significant natural defense against human breast cancer.  相似文献   
120.
Deslorelin acetate is a GnRH agonist used for contraception in dogs. This study aimed to evaluate the treatment of pre‐pubertal female dogs with deslorelin acetate implants, to better investigate the primary stimulatory effect of the drug and the long‐term effects on the genital tract, throughout repeated treatments. Sicilian hound female dogs (24) were randomly assigned to treated group, control group 1 and control group 2. First group bitches were implanted at 4.5, 9.0 and 13.5 months and monitored clinically, ultrasonographically and endocrinologically, throughout the study period (13.5 months). Control group 1 bitches were not implanted and clinically monitored for the same period. At 18 months, the animals underwent ovariohysterectomy, thus allowing evaluation of the internal genitalia. Control group 2 bitches were ovariohysterectomized at the age of 4.5 months. The suppression of oestrus was obtained in the treated group despite the fact that the first implant caused a modest increase in plasmatic levels of 17‐beta estradiol and an evident cornification of the vaginal mucosa cells (50–80%). Estradiol and progesterone were at baseline levels for the remaining study period, in which no other oestrous manifestations were observed. The external genitalia maintained a juvenile appearance. The ovaries, ultrasonographically, showed no follicular structures and stayed the same size. At 18 months, the genital tract was still juvenile with inactive small ovaries and a thin filiform uterus. Deslorelin suppressed ovarian activity in pre‐pubertal bitches, and oestrous induction was not observed despite the presence of the primary stimulatory effect of the drug. Juvenile genitalia were an expected side effect of the treatment.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号