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   312篇
  免费   18篇
林业   8篇
农学   4篇
  27篇
综合类   41篇
农作物   9篇
水产渔业   25篇
畜牧兽医   179篇
园艺   5篇
植物保护   32篇
  2023年   2篇
  2021年   4篇
  2020年   3篇
  2019年   3篇
  2018年   6篇
  2017年   6篇
  2016年   5篇
  2015年   2篇
  2014年   3篇
  2013年   6篇
  2012年   7篇
  2011年   10篇
  2010年   12篇
  2009年   11篇
  2008年   9篇
  2007年   7篇
  2006年   7篇
  2005年   7篇
  2004年   10篇
  2003年   11篇
  2002年   6篇
  2001年   6篇
  2000年   9篇
  1999年   8篇
  1998年   17篇
  1997年   15篇
  1996年   13篇
  1995年   7篇
  1994年   13篇
  1993年   12篇
  1992年   9篇
  1991年   7篇
  1990年   7篇
  1989年   11篇
  1988年   3篇
  1987年   4篇
  1986年   5篇
  1984年   2篇
  1983年   5篇
  1981年   3篇
  1980年   4篇
  1978年   2篇
  1977年   2篇
  1975年   3篇
  1973年   5篇
  1972年   6篇
  1971年   3篇
  1945年   2篇
  1943年   1篇
  1942年   1篇
排序方式: 共有330条查询结果,搜索用时 15 毫秒
161.
162.
163.
Summary: In this retrospective study, postoperative ileus was studied in horses having resection of the small intestine followed by a jejunojejunal (n=35) or a jejunocaecal (n=35) anastomosis. Twenty-six horses received no metoclopramide, 27 received metoclopramide as an intermittent intravenous infusion and 17 horses received metoclopramide as a continuous intravenous infusion (0.04 mg/kg/hour). Horses receiving a continuous infusion of metoclopramide had a reduced total volume (P< 0.001), shorter duration (P< 0.001), and a slower rate (P< 0.001) of postoperative gastric reflux, and a shorter postoperative hospital stay (P< 0.01) when compared to horses receiving no metoclopramide and horses receiving metoclopramide as an intermittent infusion. Horses having jejunocaecostomy performed had a larger volume (P< 0.05), longer duration (P< 0.05), and a greater rate (P< 0.05) of postoperative gastric reflux, and a longer postoperative hospital stay (P< 0.001) than horses undergoing jejunojejunostomy. Horses that had an abdominal drain placed during surgery had a longer length of intestine resected (P< 0.05) and a longer postoperative hospital stay (P< 0.05) than horses without an abdominal drain. Horses that died or were euthanased during the postoperative period had a greater total volume (P< 0.05), longer duration (P< 0.05), and greater rate of postoperative gastric reflux (P< 0.01), a longer length of small intestine resected (P< 0.01), and a shorter postoperative hospital stay (P< 0.05) than horses that survived until discharge from the hospital. In a multivariate regression analysis the continuous infusion of metoclopramide was the only variable that contributed significantly to predicting the total volume (P< 0.001; r2= 0.24), duration (P< 0.001; r2= 0.24) and rate (P< 0.001; r2= 0.25) of postoperative gastric reflux. We concluded that metoclopramide given as a continuous intravenous infusion decreased the incidence and severity of ileus following small intestinal resection and anastomosis in horses.  相似文献   
164.
An examination was made of the effects of three polyamine biosynthesis inhibitors on germination and appressorium formation by uredospores of the bean rust fungusUromyces viciae-fabea on artificial membranes. The ornithine decarboxylase inhibitor -difluoromethylornithine had no effect on uredospore germination, even when used at 2mM, whereas appressorium formation was reduced by 63% at 0.5 mM and by 99% at 2mM. Methylglyoxal bis(guanylhydrazone), an inhibitor of S-andenosylmethionine decarboxylase, reduced germination when used at 0.025 mM, and at this concentration, appressorium formation was completed prevented. Uredospore germination was unaffected by as much as 3 mM cyclohexylamine, an inhibitor of spermidine esynthase, while appressorium formation was reduced at 1 mM and completely prevented at 3.3 mM. These results support previous suggestions that inhibitors of polyamine biosynthesis exert their main effect on the early stages of fungal development on the leaf surface.Abbreviantions CHA cyclohyxylamine - DFMO -difluoromethylornithine - MGBG methylglyoxal bis(guanylhydrazone)  相似文献   
165.
Diagnostic imaging techniques (conventional radiography, computed tomography and magnetic resonance imaging) are an essential tool in the diagnostic work-up of ear diseases. Conventional radiography is commonly used, but often lacks sensitivity. Computed tomography (CT) and magnetic resonance (MR) are complementary imaging studies of the middle ear, labyrinth, internal auditory canal and their contents. CT provides excellent images of bony structures and is indicated where osseous changes are of greatest diagnostic importance. MR is superior in imaging soft tissue components including intralabyrinthine fluid. Therefore, more than one of these imaging techniques may be required in order to make a diagnosis.  相似文献   
166.
A study was undertaken to determine the toxic effects of cisplatin, an antineoplastic agent, when administered immediately after a 1-hour saline diuresis. Four treatments with cisplatin (70 mg/m2 of body surface, q 3 wk) were administered IV to 6 healthy dogs over a 20-minute period after 0.9% NaCl (saline) solution was administered IV for 1 hour at a volume of 132 ml (kg)0.75. Each dog vomited at least once within 8 hours after each treatment was administered. Clinical status, body weight, and food consumption were normal throughout the 12-week study for 5 of the 6 dogs. The sixth dog developed acute renal failure and became acutely blind and deaf within 3 days after the fourth treatment with cisplatin. Serum electrolyte, creatinine, and urea nitrogen values remained within established normal limits in all dogs immediately prior to each treatment, and in 5 of 6 dogs evaluated 3 weeks after the final treatment. The serum creatinine value (3.3 mg/dl) obtained from the Beagle euthanatized 2 weeks after the fourth treatment was above established normal values. Despite normalcy for all but 1 of the creatinine values, serum creatinine concentration obtained 3 weeks after the final treatment with cisplatin was significantly (P = 0.0001) higher than pretreatment values. When compared with data from all other evaluation periods, significant decreases in glomerular filtration rate, as determined by exogenous (P less than or equal to 0.0001) and endogenous (P less than or equal to 0.0001) creatinine clearance testing, were identified 3 weeks after the fourth treatment with cisplatin.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
167.
Calculations indicate that chlorofluoromethanes produced by man can greatly affect the concentrations of stratospheric ozone in future decades. This effect follows the release of chlorine from these compounds in the stratosphere. Present usage levels of chlorofluoromethanes can lead to chlorine-catalyzed ozone destruction rates that will exceed natural sinks of ozone by 1985 or 1990.  相似文献   
168.
169.
170.
Studies were conducted to assess whether basal ganglia output neurons originating in the substantia nigra pars reticulata might be affected by dopamine released from dendrites of neighboring substantia nigra pars compacta neurons. Dopamine applied by iontophoresis increased the baseline firing rates of approximately half of the substantia nigra pars reticulata cells tested. The more significant finding, unrelated to the increase in firing, was the ability of dopamine to attenuate the inhibitory responses of these cells to iontophoretically applied gamma-aminobutyric acid. These findings suggest a role for dopamine as a neuromodulator and further suggest that it can act at sites beyond the striatum to modify transmission from the basal ganglia to motor nuclei.  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