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   225篇
  免费   21篇
林业   7篇
农学   7篇
  20篇
综合类   27篇
农作物   8篇
水产渔业   19篇
畜牧兽医   148篇
园艺   1篇
植物保护   9篇
  2022年   4篇
  2021年   3篇
  2020年   9篇
  2019年   13篇
  2018年   7篇
  2017年   6篇
  2016年   7篇
  2015年   8篇
  2014年   8篇
  2013年   6篇
  2012年   9篇
  2011年   20篇
  2010年   8篇
  2009年   3篇
  2008年   10篇
  2007年   6篇
  2006年   7篇
  2005年   8篇
  2004年   3篇
  2003年   13篇
  2002年   4篇
  2001年   6篇
  2000年   11篇
  1999年   7篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1995年   1篇
  1994年   1篇
  1993年   2篇
  1992年   3篇
  1991年   8篇
  1990年   7篇
  1989年   5篇
  1988年   2篇
  1987年   1篇
  1986年   1篇
  1985年   7篇
  1984年   2篇
  1981年   2篇
  1980年   2篇
  1979年   2篇
  1978年   1篇
  1976年   1篇
  1974年   1篇
  1972年   3篇
  1969年   1篇
  1968年   2篇
排序方式: 共有246条查询结果,搜索用时 0 毫秒
91.
In Asia, Monopterus albus (Asian swamp eel) is commonly found in rice fields, muddy ponds and swamp areas. Because of its habitat, it is exposed to toxic pesticides used in rice fields, especially endosulfan, which is one of the most widely used insecticides. This study aims to determine the acute toxicity of endosulfan and its effect on the behaviour and some hematological parameters of the fish. The 96 h-LC50 (with 95% confidence limits) obtained in this study for M. albus was 0.42 (0.35-0.50) μg L−1. After 96 h exposure to endosulfan, the fish exhibited a series of abnormal behavioural responses; these included imbalanced position, restlessness of movement, erratic swimming, tremor, flashing and lethargy. When the swamp eels were exhausted, they were laterally recumbent on the bottom and had no opercula movement. Endosulfan toxicity also caused a significant lower (p < 0.05) value of erythrocyte count, leukocyte count, hemoglobin and hematocrit as compared to the control experiment. Nevertheless, the erythrocyte cell showed an increasing trend in size. The swollen erythrocyte cells may be impaired in their oxygen-carrying capacity. Severe blood loss through the gill capillary and hematemesis of the fish may be the main reasons for the hematological changes in the test organisms. Despite its relatively bigger size (30-40 cm in length) as compared to most of the other test organisms (<5 cm in length) for endosulfan toxicity, it is interesting to find that this fish is one of the most sensitive freshwater fishes to endosulfan.  相似文献   
92.
Uncorrected hypercalcemia can cause clinical signs such as polyuria, polydipsia, vomiting, diarrhea, lethargy, and depression and contributes to the development of primary renal failure and soft tissue mineralization. Treatment of hypercalcemia includes diagnosis and treatment of the underlying disease process and some combination of excracellular fluid volume expansion by administration of fluids intravenously and administration of glococorticosteroids, salmon calcitonin, and furosemide. Bisphosphonates such as pamidronate disodium also may be safe and effective in the treatment of hypercalcemia. The purpose of our study was to characterize the efficacy and safety of pamidronate in the treatment of hypercalcemia attritutable to several different disease processes in the dog and cat. Seven dogs and 2 cats were administered pamidronate at a dose of 1.05-2.0 mg/kg IV for a variety of disease processes, including neoplasia (n = 4), calcipotriene toxicity (n = 3), nocardiosis (n = 1), and idiopathic hypercalcemia with chronic renal failure (n = 1). In all the animals, IV pamidronate administration rapidly decreased serum calcium concentrations without evident toxicosis. Two animals received pamidronate several times without obvious toxicosis. On the basis of the findings in our retrospective study, pamidronate may be a safe and effective drug with which to lower both serum total and ionized calcium concentrations in patients with hypercalcemia arising from a wide variety of underlying disease processes.  相似文献   
93.
94.
Framework species are indigenous tree species planted in a mixed stand to accelerate natural regeneration of forest and encourage biodiversity regeneration. In this study we used the framework species method to make multipurpose tree gardens to provide traditional healers with woody species used for medicine and other needs like food and firewood. We specifically determined the phenology, germination behaviour, survival and growth after planting 19 indigenous and 8 introduced woody species. The species were planted in a mixed stand together at a density of 3125 ha−1. Field performance was assessed by monitoring survival, height and crown width once every month for 13 months after planting. Eleven species (Artocarpus heterophyllus, Calliandra calothyrsus, Callistemon citrinus, Carica papaya, Carissa spinarum, Leucaena leucocephala, Markhamia lutea, Sarcocephalus latifolius, Senna siamea, S. spectabilis and Terminalia schimperiana) proved to be excellent framework species. Eight species qualified as ‘acceptable’ FWS (Albizia coriaria, Ceiba pentranta, Entada abyssinica, Erythrina abyssinica, Eugenia jambos, Ficus sycomorus, Maesopsis eminii and Milicia excelsa), while seven species were ranked as ‘marginally acceptable’ (Acacia macrothyrsa, Calpurnia aurea, Canarium schweinfurthii, Capparis tomentosa, Ficus natalensis, Senna sp. and Warburgia salutaris). Annona squamosa was the only species rejected since both germination and survival was low. Trees with good reforestation traits could be recommended for planting while the species that were marginally acceptable or rejected require extra research since some of them are important medicinal woody species of conservation concern.  相似文献   
95.
OBJECTIVE: To evaluate transurethral cystoscopy and excretory urography for diagnosis of ectopic ureter in female dogs and identify concurrent urogenital abnormalities. DESIGN: Retrospective study. ANIMALS: 25 female dogs. PROCEDURE: Medical records of female dogs that underwent transurethral cystoscopy, excretory urography, and ventral cystotomy were reviewed for signalment, history, physical examination findings, results of bacteriologic culture of urine, and surgical findings. Videotapes of transurethral cystoscopy and radiographic studies were reviewed systematically without knowledge of surgical findings. RESULTS: Ectopic ureters were diagnosed in 24 of 25 (96%) of the dogs, bilaterally in 22 of 24 (91.6%) dogs. Cystoscopic evaluation yielded a correct diagnosis in all dogs when results of ventral cystotomy were used as the diagnostic standard. Cystoscopic evaluation identified a terminal ureteral opening for all ureters. Urethral fenestrations, troughs, striping, and tenting were identified. Abnormalities of the vestibule were identified in all examinations available for review (24/25). The paramesonephric septal remnant and its association with ectopic ureters were identified and characterized by cystoscopy. Radiographic findings were discordant with surgical findings and correctly identified 36 of 46 (78.2%) ectopic ureters and 2 of 4 normal ureters. Hydroureter and renal abnormalities were associated with distal urethral ectopic ureters on radiographic evaluations. CONCLUSIONS AND CLINICAL RELEVANCE: Transurethral cystoscopy was accurate and minimally invasive for identification and classification of ectopic ureters in dogs. Contrast radiography had limitations in diagnosis of ectopic ureters. Cystoscopic findings and associated vaginal and vestibular abnormalities support abnormal embryologic development in the pathogenesis of ectopic ureters.  相似文献   
96.
Dietary lutein stimulates immune response in the canine   总被引:7,自引:0,他引:7  
The possible immuno-modulatory action of dietary lutein in dogs is not known. Female Beagle dogs (17-18-month old; 11.4+/-0.4kg body weight) were supplemented daily with 0, 5, 10 or 20mg lutein for 12 weeks. Delayed-type hypersensitivity (DTH) response to saline, phytohemagglutinin (PHA) and a polyvalent vaccine was assessed on Weeks 0, 6 and 12. Blood was sampled on Weeks 0, 2, 4, 8 and 12 to assess (1) lymphocyte proliferative response to PHA, concanavalin A (Con A), and pokeweed mitogen (PWM), (2) changes in peripheral blood mononuclear cell (PBMC) populations, (3) interleukin-2 (IL-2) production and (4) IgG and IgM production. After the completion of 12-week study, we continued to collect the blood weekly up to 17 weeks to evaluate the changes in immunoglobulin production upon first and second antigenic challenges on Weeks 13 and 15. Plasma lutein+zeaxanthin was undetectable in unsupplemented dogs but concentrations increased (P<0.05) rapidly on Week 2 in lutein-supplemented dogs. Thereafter, concentrations generally continued to increase in dose-dependent manner, albeit at a much slower rate. Dogs fed lutein had heightened DTH response to PHA and vaccine by Week 6. Dietary lutein increased (P<0.05) lymphocyte proliferative response to all three mitogens and increased the percentages of cells expressing CD5, CD4, CD8 and major histocompatibility complex class II (MHC II) molecules. The production of IgG increased (P<0.05) in lutein-fed dogs after the second antigenic challenge. Lutein did not influence the expression of CD21 lymphocyte marker, plasma IgM or IL-2 production. Therefore, dietary lutein stimulated both cell-mediated and humoral immune responses in the domestic canine.  相似文献   
97.

Background

Long‐term treatment of cats with ionized hypercalcemia using alendronate has not been evaluated.

Hypothesis/Objectives

Alendronate is well tolerated in treatment of ionized hypercalcemia in cats.

Animals

A total of 12 cats with ionized hypercalcemia.

Methods

Prospective study of 12 cats with ionized hypercalcemia of idiopathic origin was identified by telephone and email communication with a convenience sample of consulting veterinarians. Cats were treated with alendronate at a dose of 5–20 mg per feline PO q7d. Serum ionized calcium concentration (iCa) was measured before beginning treatment with alendronate, and after 1, 3, and 6 months of treatment. Alendronate dosage was adjusted according to iCa. Evaluation included physical examination, CBC, biochemistry profile, and diagnostic imaging. The owners and referring veterinarians were questioned about any observed adverse effects. The Wilcoxon matched‐pairs signed rank test was used to compare baseline iCa to iCa at different time periods.

Results

Alendronate treatment resulted in a decrease in iCa in all 12 cats. The median percentage change in iCa was −13.2%, −15.9%, and −18.1% (range, −29.6 to +7.6; −30.5 to −1.9; −45.8 to +1.5%) at the 1, 3, and 6 month time points, respectively. Baseline iCa was significantly different from 1 month (P = .0042), 3 months (P = .0005), and 6 months (P = .0015). No adverse effects were reported for any of the cats.

Conclusions and Clinical Importance

Alendronate was well tolerated and decreased iCa in most cats for the 6‐month period of observation.  相似文献   
98.
The oncolytic effects of reovirus in various cancers have been proven in many clinical trials in human medicine. Oncolytic virotherapy using reovirus for canine cancers is being developed in our laboratory. The objective of this study was to examine the synergistic anti-cancer effects of a combination of reovirus and low doses of various chemotherapeutic agents on mammary gland tumors (MGTs) in dogs. The first part of this study demonstrated the efficacy of reovirus in canine MGTs in vitro and in vivo. Reovirus alone exerted significant cell death by means of caspase-dependent apoptosis in canine MGT cell lines. A single injection of reovirus impeded growth of canine MGT tumors in xenografted mice, but was insufficient to induce complete tumor regression. The second part of this study highlighted the anti-tumor effects of reovirus in combination with low doses of paclitaxel, carboplatin, gemcitabine, or toceranib. Enhanced synergistic activity was observed in the MGT cell line treated concomitantly with reovirus and in all the chemotherapeutic agents except toceranib. In addition, combining reovirus with paclitaxel or gemcitabine at half dosage of half maximal inhibitory concentration (IC50) enhanced cytotoxicity by activating caspase 3. Our data suggest that the combination of reovirus and low dose chemotherapeutic agents provides an attractive option in canine cancer therapy.  相似文献   
99.
Lam PY  Yan CW  Chiu PY  Leung HY  Ko KM 《Fitoterapia》2011,82(3):393-400
Schisandrin B (Sch B) and schisandrin C (Sch C), but not schisandrin A and dimethyl diphenyl bicarboxylate, protected rat skin tissue against solar irradiation-induced oxidative injury, as evidenced by a reversal of solar irradiation-induced changes in cellular reduced glutathione and α-tocopherol levels, as well as antioxidant enzyme activities and malondialdehyde production. The cytochrome P-450-mediated metabolism of Sch B or Sch C caused ROS production in rat skin microsomes. Taken together, Sch B or Sch C, by virtue of its pro-oxidant action and the subsequent eliciting of a glutathione antioxidant response, may prevent photo-aging of skin.  相似文献   
100.
Ureteral ectopia is a congenital abnormality of the terminal segment of one or both ureters in which the ureteral orifice is located distal to the trigone of the bladder. Continuous or intermittent urinary incontinence is the most frequently reported clinical symptom associated with ureteral ectopia. A variety of anatomic morphologies of ectopic ureters have been reported. Historically, surgical therapy focused on reestablishing drainage of the ureters into the bladder lumen. However, continued urinary incontinence after surgery is the most frequently reported complication. Specific classification and successful management of the various types of ectopic ureters remain diagnostic and therapeutic challenges to the veterinary clinician. Cystoscopic evaluation of the lower urinary tract and urodynamic evaluation of bladder and urethral function has improved the presurgical assessment of the patient. Surgical procedures, which are aimed at repositioning the ureteral orifice(s) within the bladder lumen and treating primary sphincter incompetence, are necessary to successfully manage small animal patients with ectopic ureters.  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