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   239篇
  免费   20篇
林业   1篇
  5篇
综合类   32篇
农作物   5篇
水产渔业   5篇
畜牧兽医   204篇
植物保护   7篇
  2023年   1篇
  2021年   1篇
  2020年   3篇
  2019年   3篇
  2018年   9篇
  2017年   6篇
  2016年   7篇
  2015年   4篇
  2014年   6篇
  2013年   13篇
  2012年   7篇
  2011年   7篇
  2010年   18篇
  2009年   20篇
  2008年   15篇
  2007年   11篇
  2006年   6篇
  2005年   1篇
  2004年   6篇
  2003年   7篇
  2002年   2篇
  2001年   8篇
  2000年   4篇
  1999年   11篇
  1998年   14篇
  1997年   9篇
  1996年   13篇
  1995年   7篇
  1994年   2篇
  1993年   4篇
  1992年   6篇
  1991年   7篇
  1990年   7篇
  1989年   5篇
  1988年   2篇
  1986年   1篇
  1985年   3篇
  1983年   1篇
  1982年   1篇
  1960年   1篇
排序方式: 共有259条查询结果,搜索用时 31 毫秒
11.
A 5-year-old Holstein cow, pregnant with a valuable calf, was presented with signs of heart failure (tachycardia, peripheral edema, and distended jugular veins) related to pericardial lymphoma and associated cardiac tamponade. In addition, pleural effusion was present in both hemithoraces. Medical treatment, which consisted of repeated pericardiocenteses, placement of indwelling pleural catheters, administration of intravenous fluid therapy, antibiotics and anti-inflammatory drugs, was ineffective in controlling recurrence of clinical signs despite a temporary improvement. A standing thoracoscopic pericardiotomy was performed in an attempt to reduce clinical signs of heart failure and to prolong life. Clinical signs of heart failure abated and no recurrence was seen. Standing thoracoscopic pericardiotomy along with possible corticosteroids can be recommended as palliative treatment in an effort to extend life for reproductive performance in genetically valuable animals.  相似文献   
12.
13.
Objective To examine whether sub-optimal temperature induced stress and immunosuppression in farmed saltwater crocodile (Crocodylus porosus) hatchlings. Design A clinico-pathological study. Animals A total of 140 hatchlings were used. Procedure Body weight and length, plasma corticosterone and immunoglobulin concentrations and total and differential white blood cell counts were measured in 140 hatchlings from five clutches divided between five water temperature treatment groups. Initially all groups were housed at 32°C for 10 weeks, then two groups (L, LC) were changed to low temperature (28°C) and two groups (H, HC) to high temperature (36°C), while one group (C) remained at 32°C. The LC and HC groups were maintained at these temperatures for 10 days, after which the water temperature of both groups was returned to 32°C. Blood samples were collected twice (at 6 and 9 weeks of age) before the initial temperature change, and at 10 days and 4 weeks after the initial temperature change (at 11.5 and 14 weeks of age). Results Except for an increase in plasma corticosterone in the HC group and a decrease in the L group when the temperature change was first introduced, changes in plasma corticosterone were not significant. There were no significant changes in immunoglobulin concentrations. There were, however, significant decreases in the total white cell and lymphocyte counts in the LC group after the temperature was decreased to 28°C, and an increase in these counts after water temperature was returned to 32°C. Clutch of origin had significant effects on body weight and length gains, and there were negative relationships between body weight and corticosterone concentrations and between body weight and immunoglobulin concentrations. Conclusions As haematological changes indicative of stress were not associated with significant changes in serum corticosterone, immunosuppression in young crocodiles may be independent of the hypothalamic-pituitary-adrenal cortical axis.  相似文献   
14.
Proteins in sporulated and unsporulated oocysts of Eimeria maxima were characterized, using monoclonal antibodies (MAB), ELISA, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and protein (western) immunoblotting techniques. Three MAB (EM1, EM2, and EM4) were produced against proteins of sporulated oocysts. The ELISA results indicated that EM1 was reactive with sporulated oocyst proteins, EM2 was reactive with sporulated and unsporulated oocyst proteins, and EM4 was reactive with unsporulated oocysts and proteins. Separation of proteins in E maxima sporulated and unsporulated oocysts by SDS-PAGE indicated that sporulated oocysts had proteins of approximately 200 kilodaltons (kD) and distinct protein bands at 21.5 and 45 kD. Using SDS-PAGE, unsporulated oocysts had less-distinct high molecular weight protein bands (greater than 200 kD), compared with sporulated oocysts, and a distinct protein band at 31 kD. Use of all 3 MAB yielded negative results in western blot analysis of fractions obtained by SDS-PAGE.  相似文献   
15.
The relationship between the serological classification system for serogroup B and for serogroup H of Bacteroides nodosus and cross-protection between subgroups within these serogroups was examined. Protection against ovine footrot following vaccination was achieved against other subgroup strains provided sufficient cross-reactive antibody was induced by shared pilus antigens. Within serogroup B, better cross-protection against one subgroup was obtained with a pili vaccine than a whole cell vaccine which correlated with higher pilus antibody titres induced by the former. For serogroup H, a lack of cross-protection and serological reactivity between subgroups was demonstrated, which indicates that the prototype strain of subgroup H2 should be designated a new serogroup.  相似文献   
16.
17.
18.
Three monoclonal antibodies produced against Leptospira interrogans serovar pomona have been studied for their diagnostic usefulness. All three monoclonals reacted strongly in the enzyme-linked immunosorbent assay and indirect fluorescent antibody test with serovar pomona and did not react with serovars grippotyphosa, canicola, icterohaemorrhagiae and hardjo.  相似文献   
19.
Experimental additions of ammonium sulphate to a nitrogen-poor dry heathland have been carried out since 1989. There are four nitrogen treatments: a control (receiving artificial rain only), a low treatment which receives an additional 7.7 kg N ha?1 yr?1, a high treatment receiving 15.4 kg N ha?1 yr?1 and an alternating treatment which receives either the control or the high nitrogen additions, in alternate years. The estimated background deposition at the study site is 13–18 kg N ha?1 yr?1, a value similar to the critical load that has been suggested for the conversion of lowland heath to grassland. Over the past 5 years there have been significant stimulations in shoot growth, flowering, canopy density and litter production. Flowering, in particular, strongly reflects nitrogen additions in the alternating treatment. Current models of the response of dry Calluna heathlaud to enhanced nitrogen deposition suggest that higher tissue nitrogen levels will occur and will be accompanied by heightened sensitivity to secondary stresses. This may in turn lead to canopy breakdown and replacement by grassland. The application of nitrogen at deposition rates only slightly in excess of the critical load over five years has produced small, non-significant increases in shoot nitrogen content. However, there is clear evidence of a large positive effect on shoot growth, flowering, litter production and canopy density of Calluna. The observation of these responses at the application rates used in this study supports the current proposals for critical loads of nitrogen for lowland heaths.  相似文献   
20.
The formyl cation, HCO+, has long been believed to be an important intermediate in the chemistry of carbon monoxide (CO) in acidic environments, but its spectroscopic observation in solution has been elusive. This species was generated by the reaction of CO with the liquid superacid hydrofluoric acid-antimony pentafluoride (HF-SbF5) under pressure and was observed by nuclear magnetic resonance and infrared spectroscopy. Equilibria between CO in the gas phase, CO dissolved in HF-SbF5, the SbF5 adduct of formyl fluoride, and HCO+ associated with several equilibrating anions of the type [SbxF5x+1]- are proposed to describe the system.  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