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   372篇
  免费   11篇
林业   11篇
农学   17篇
基础科学   6篇
  24篇
综合类   79篇
农作物   4篇
水产渔业   3篇
畜牧兽医   194篇
园艺   9篇
植物保护   36篇
  2021年   3篇
  2020年   3篇
  2019年   3篇
  2018年   4篇
  2017年   7篇
  2016年   4篇
  2014年   7篇
  2013年   10篇
  2012年   14篇
  2011年   12篇
  2010年   6篇
  2009年   5篇
  2008年   11篇
  2007年   14篇
  2006年   10篇
  2005年   13篇
  2004年   4篇
  2003年   9篇
  2002年   13篇
  2001年   9篇
  2000年   12篇
  1999年   12篇
  1998年   6篇
  1997年   6篇
  1996年   4篇
  1995年   3篇
  1993年   4篇
  1992年   14篇
  1991年   10篇
  1990年   5篇
  1989年   8篇
  1988年   17篇
  1987年   8篇
  1986年   20篇
  1985年   14篇
  1984年   7篇
  1983年   6篇
  1982年   3篇
  1981年   4篇
  1979年   7篇
  1978年   4篇
  1977年   7篇
  1975年   4篇
  1974年   3篇
  1973年   5篇
  1972年   2篇
  1971年   2篇
  1970年   2篇
  1968年   2篇
  1967年   3篇
排序方式: 共有383条查询结果,搜索用时 0 毫秒
1.
A 13-year-old neutered female Yorkshire terrier presented with a history of progressive episodic weakness and disorientation of 4 months duration. Physical and neurologic examinations were normal at presentation. Abdominal ultrasound revealed a mass involving the right adrenal gland. Standard planar scintigraphy was performed at 4, 18, and 24 hours after intravenous injection 185 MBq (5mCi) of 123I-labeled metaiodobenzylguanidine (123I-MIBG). An area of focal intense uptake was identified in the area of the right adrenal gland. A pheochromocytoma was confirmed histologically after surgical excision.  相似文献   
2.
3.
Mechanical inoculations with contaminating tools and propagation of infected budwood were considered the main causes for the omnipresence of multiple viroid species among citrus and other Middle Eastern and Mediterranean fruit trees and grapevines. However, neither means could explain viroid infections of wild trees — scattered on terrains inaccessible to humans — nor the finding of similar viroids among graft-incompatible plants. Northern hybridization of RNA extracts made of scrapings from the surfaces of goat (Capra hircus) horns that were rubbed against etrog (Citrus medica) stems infected with a citrus viroids complex, revealed accumulation of considerable amounts ofCitrus exocortis viroids (CEVd) andHop stunt viroids (HSVd). Experimental transmission of both CEVd and HSVd was obtained by rubbing healthy citrus plants with goat horns that had been rubbed 24 h earlier on infected etrog stems. These results implicate goats as possible vectors of viroids. Transmissionvia goats could have facilitated the long-range spread of viroids among cultivated and wild plants andvice versa and also among graft-incompatible plants.  相似文献   
4.
5.
As a result of rapid land development in Israel during the past three decades, some 26 species of higher plants, about one percent of the local flora, have become extinct. In addition to listing such species, this paper deals with the ecological implications of this finding. Recommendations for the prevention of further damage to the local flora, and rare plants in particular, are given.  相似文献   
6.
Many dogs with chronic illness have serum biochemical abnormalities consistent with hyperadrenocorticism (HAC). Lymphoma (LSA) is a chronic disease of dogs. The purpose of this study was to evaluate adrenocortical screening test results in dogs with LSA to evaluate their specificity. Criteria for inclusion in the study included a diagnosis of LSA, an expected survival time of 16-56 weeks, no glucocorticoid treatment beyond 4 weeks after the initiation of chemotherapy, no evidence of HAC, and owner consent. Post-ACTH stimulation plasma cortisol concentrations (PACs), urine cortisol : creatinine (UC : Cr) ratios, and maximal left adrenal width measurements were performed at the time of LSA diagnosis before the initiation of chemotherapy and at 16, 24, 32, 40, and 52 weeks or until the loss of remission or the development of another disease. Ten dogs met the criteria for inclusion. Forty-two PACs were performed; 1 abnormal, 2 borderline, and 39 normal values were detected. Thirty-five maximal left adrenal width measurements were obtained; 0 abnormal, 5 borderline, and 30 normal measurements were detected. Thirty-six UC : Cr ratios were obtained, with 26 abnormal, 4 borderline, and 6 normal values detected and 9 of 10 dogs having at least 1 abnormal value. These data suggest that in dogs with LSA, the UC : Cr ratio frequently is abnormal and may not be a specific test for HAC, or it may be the most sensitive test for increases in cortisol secretion due to chronic illness. Maximal left adrenal width measurements and PACs were almost always normal and may be more specific for HAC or less sensitive for demonstrating chronic increases in cortisol secretion.  相似文献   
7.
Medical records of 104 cats with diabetes mellitus were reviewed. Information from 54 cats that had multiple blood glucose concentrations evaluated at least 5 times over a minimum of 3 months, beginning at the time insulin treatment was initiated, was used to evaluate the efficacy of insulin in treating diabetes mellitus. Fourteen of 54 cats were treated with protamine zinc insulin (PZI), 26 with ultralente insulin, and 14 with lente insulin. Six, 29, and 19 cats had good, mediocre, and poor glycemic control, respectively, based on mean blood glucose concentrations, whereas 31, 21, and 2 owners thought clinical response was good, mediocre, and poor, respectively. No significant difference was found in glycemic control among cats treated with PZI, ultralente, or lente insulin. Glycemic control was significantly (P < .05) better in 33 cats without than in 21 cats with concurrent disease. All 104 cats were used to calculate survival data. Fifty-one of 104 cats were alive at the time of the study. Mean (± standard deviation [SD]) and median survival times were 24 (± 16) and 20 months, respectively, in the 51 cats still alive at the end of the evaluation, and 25 (± 4) and 17 months, respectively, in the 53 cats that had died during the period of evaluation. Pancreatic abnormalities identified in 37 cats that underwent necropsy included chronic pancreatitis (n = 17), acute to subacute pancreatitis (n = 2), exocrine pancreatic adenocarcinoma (n = 7) and adenoma (n = 1), islet cell atrophy and vacuolar degeneration (n = 27), and islet amyloidosis (n = 8). No association was found between glycemic control and islet amyloidosis or exocrine pancreatic neoplasia, or between survival time and chronic pancreatitis, islet amyloidosis, or exocrine pancreatic neoplasia. In conclusion, diabetic cats evaluated in this study showed a variable response to exogenously administered insulin, ranging from excellent to poor. By maintaining mean blood glucose concentrations under 300 mg/dL, clinical signs were improved, and owners were satisfied with insulin treatment. Concurrent potentially insulin-antagonistic diseases were common and deleteriously affected glycemic control and survival time.  相似文献   
8.
Plasma fibronectin concentrations of 148 normal canine samples were measured by rocket immunoelectrophoresis. Electrophoresis was accomplished, using 2.0% rabbit anticanine fibronectin by volume in 0.7% agarose in buffer. Films were electrophoresed 18 hours in barbital buffer, 7.5 mA/film. The mean fibronectin concentration for normal citrated dog plasma was 290 micrograms/ml +/- 50 micrograms/ml.  相似文献   
9.
Glucose tolerance and insulin response in normal-weight and obese cats   总被引:2,自引:0,他引:2  
Glucose tolerance and insulin response were evaluated in 9 normal-weight and 6 obese cats after IV administration of 0.5 g of glucose/kg of body weight. Blood samples for glucose and insulin determinations were collected immediately prior to and 2.5, 5, 7.5, 10, 15, 30, 45, 60, 90, and 120 minutes after glucose infusion. Baseline glucose concentrations were not significantly different between normal-weight and obese cats; however, mean +/- SEM glucose tolerance was significantly impaired in obese vs normal-weight cats after glucose infusion (half time for glucose disappearance in serum--77 +/- 7 vs 51 +/- 4 minutes, P less than 0.01; glucose disappearance coefficient--0.95 +/- 0.10 vs 1.44 +/- 0.10%/min, P less than 0.01; insulinogenic index--0.20 +/- 0.02 vs 0.12 +/- 0.01, P less than 0.005, respectively). Baseline serum insulin concentrations were not significantly different between obese and normal-weight cats. Insulin peak response after glucose infusion was significantly (P less than 0.005) greater in obese than in normal-weight cats. Insulin secretion during the first 60 minutes (P less than 0.02), second 60 minutes (P less than 0.001), and total 120 minutes (P less than 0.0003) after glucose infusion was also significantly greater in obese than in normal-weight cats. Most insulin was secreted during the first hour after glucose infusion in normal-weight cats and during the second hour in obese cats. The impaired glucose tolerance and altered insulin response to glucose infusion in the obese cats was believed to be attributable to deleterious effects of obesity on insulin action and beta-cell responsiveness to stimuli (ie, glucose).  相似文献   
10.
Splenectomy was done in 9 dogs having immune-mediated hematologic disorders refractory to medical therapy. These disorders were immune-mediated thrombocytopenia (n = 3), immune hemolytic anemia (n = 3), and Evan's syndrome (n = 3). The diagnoses were based on clinical observations, laboratory test data, and differential of other conditions. In the 12 months after splenectomy was done, the dogs reflected clinical improvement and return of platelet and/or erythrocyte counts to clinically acceptable limits; medical treatment was stopped or reduced in 8 of 9 patients. The exceptional patient had shown clinical improvement without change in the platelet count. At the end of 1 year, survival rate was excellent, and postsplenectomy complications, such as hemobartonellosis, did not appear. It is believed that splenectomy may be useful for treating immune-mediated thrombocytopenia, anemia, and Evan's syndrome that seem refractory to medication.  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