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   301篇
  免费   14篇
林业   111篇
农学   2篇
  16篇
综合类   19篇
农作物   8篇
水产渔业   4篇
畜牧兽医   144篇
园艺   3篇
植物保护   8篇
  2018年   3篇
  2017年   4篇
  2016年   8篇
  2014年   5篇
  2013年   12篇
  2012年   12篇
  2011年   10篇
  2010年   11篇
  2009年   10篇
  2008年   7篇
  2007年   10篇
  2006年   28篇
  2005年   13篇
  2004年   3篇
  2003年   4篇
  2002年   8篇
  2000年   3篇
  1999年   3篇
  1998年   3篇
  1997年   5篇
  1996年   6篇
  1994年   3篇
  1993年   8篇
  1992年   4篇
  1987年   4篇
  1986年   3篇
  1985年   3篇
  1983年   3篇
  1982年   3篇
  1980年   7篇
  1979年   5篇
  1938年   3篇
  1936年   3篇
  1931年   4篇
  1930年   3篇
  1926年   3篇
  1925年   2篇
  1924年   3篇
  1922年   2篇
  1916年   2篇
  1915年   3篇
  1913年   2篇
  1909年   7篇
  1908年   5篇
  1907年   2篇
  1906年   5篇
  1902年   3篇
  1901年   2篇
  1898年   3篇
  1894年   2篇
排序方式: 共有315条查询结果,搜索用时 250 毫秒
81.
The importation of 18 Collembola and 7 Zygentoma species to Hamburg is recorded. The most are found on living plants (Orchidaceae and Cactaceae) and in wood. OnlyLepisma saccharina L. andLepismodes inquilinus Newman are house and stored-product pests. The first is common in houses, but don't live in open air in Germany, the later has infected some bakeries in Hamburg only; others findings in Germany are also mentioned. The distribution and origin countries of the Collembola are mostly still not or unsufficiently known, perhaps some are original cosmopolitan and some others man made cosmopolitan. Therefore the literary references on distribution are often not congruent to the declaration of exporting countries.  相似文献   
82.
Zusammenfassung Es wird über Schäden an Holzhäusern und Bautätigkeit vonAnacanthotermes ochraceus (Burmeister) in Saudi-Arabien berichtet und die Verbreitung aller paläarktischenAnacanthotermes-Arten diskutiert. Es wird eine Liste aller bisher in Arabien festgestellten 15 Temitenarten gegeben, von denenMicrocerotermes gabrielis (Weidner) ersmalig genannt wird.
Anacanthotermes ochraceus (Burmeister) (Isoptera, Hodotermitidae) as a pest on wood-houses in Arabia and a list of all termite species recorded hitherto from Arabia as well as a view of the distribution of palaearactic Anacanthotermes-species
The destructions on wood-houses and the building activities ofAnacanthotermes ochraceus (Burmeister) in Saudi-Arabia are recorded and the distribution of the palaearctic species ofAnacanthotermes is dicussed. A list of the 15 termite, species hitherto known from Arabia is also given.Microcerotermes gabrielis Weidner is new for this region.


Mit 8 Abbildungen  相似文献   
83.
84.
85.
86.
Objective – To discuss 3 potential mechanisms for loss of peripheral vasomotor tone during vasodilatory shock; review vasopressin physiology; review the available animal experimental and human clinical studies of vasopressin in vasodilatory shock and cardiopulmonary arrest; and make recommendations based on review of the data for the use of vasopressin in vasodilatory shock and cardiopulmonary arrest. Data Sources – Human clinical studies, veterinary experimental studies, forum proceedings, book chapters, and American Heart Association guidelines. Human and Veterinary Data Synthesis – Septic shock is the most common form of vasodilatory shock. The exogenous administration of vasopressin in animal models of fluid‐resuscitated septic and hemorrhagic shock significantly increases mean arterial pressure and improves survival. The effect of vasopressin on return to spontaneous circulation, initial cardiac rhythm, and survival compared with epinephrine is mixed. Improved survival in human patients with ventricular fibrillation, pulseless ventricular tachycardia, and nonspecific cardiopulmonary arrest has been observed in 4 small studies of vasopressin versus epinephrine. Three large studies, though, did not find a significant difference between vasopressin and epinephrine in patients with cardiopulmonary arrest regardless of initial cardiac rhythm. No veterinary clinical trials have been performed using vasopressin in cardiopulmonary arrest. Conclusion – Vasopressin (0.01–0.04 U/min, IV) should be considered in small animal veterinary patients with vasodilatory shock that is unresponsive to fluid resuscitation and catecholamine (dobutamine, dopamine, and norepinephrine) administration. Vasopressin (0.2–0.8 U/kg, IV once) administration during cardiopulmonary resuscitation in small animal veterinary patients with pulseless electrical activity or ventricular asystole may be beneficial for myocardial and cerebral blood flow.  相似文献   
87.
88.
Objective – To compare cardiac output (CO) measured by use of lithium dilution (LiDCO) and ultrasound velocity dilution (UDCO) in conditions of high, intermediate, and low CO in anesthetized foals.
Design – Original prospective study.
Setting – University teaching hospital.
Animals – Six foals 1–3 days of age (38–45 kg).
Interventions – Neonatal foals were anesthetized and instrumented to measure direct blood pressure, heart rate, arterial blood gases, and CO. The CO was measured by use of LiDCO and UDCO techniques. Measurements were obtained from each foal at baseline and during low, intermediate, and high CO states. Measurements were converted to cardiac index (cardiac index=CO/body weight) values for statistical analysis. Agreement between the 2 methods was determined using Bland and Altman analysis and concordance correlation coefficients.
Measurements and Main Results – LiDCO determinations of CO ranged between 4.0 and 14.0 L/min resulting in cardiac index ranging between 75.5 and 310 mL/kg/min. There was no significant effect of blood pressure variation on bias or relative bias ( P =0.62 and 0.93, respectively). The mean bias and relative bias of UDCO (±SD) compared with LiDCO were −20.1±39.2 mL/kg/min and −7.7±23.4%, respectively. Concordance correlation coefficient between LiDCO and UDCO was 0.833.
Conclusions – When compared with LiDCO, the UDCO technique has acceptable clinical utility for measuring CO in healthy anesthetized newborn foals.  相似文献   
89.
ObjectiveTo evaluate the effects of detomidine on visceral and somatic nociception, heart and respiratory rates, sedation, and duodenal motility and to correlate these effects with serum detomidine concentrations.Study designNonrandomized, experimental trial.AnimalsFive adult horses, each with a permanent gastric cannula weighing 534 ± 46 kg.MethodsVisceral nociception was evaluated by colorectal (CRD) and duodenal distension (DD). The duodenal balloon was used to assess motility. Somatic nociception was assessed via thermal threshold (TT). Nose–to–ground (NTG) height was used as a measure of sedation. Serum was collected for pharmacokinetic analysis. Detomidine (10 or 20 μg kg?1) was administered intravenously. Data were analyzed by means of a three–factor anova with fixed factors of treatment and time and random factor of horse. When a significant time × treatment interaction was detected, differences were compared with a simple t–test or Bonferroni t–test. Significance was set at p < 0.05.ResultsDetomidine produced a significant, dose–dependent decrease in NTG height, heart rate, and skin temperature and a significant, nondose–dependent decrease in respiratory rate. Colorectal distension threshold was significantly increased with 10 μg kg?1 for 15 minutes and for at least 165 minutes with 20 μg kg?1. Duodenal distension threshold was significantly increased at 15 minutes for the 20 μg kg?1 dose. A significant change in TT was not observed at either dose. A marked, immediate decrease in amplitude of duodenal contractions followed detomidine administration at both doses for 50 minutes.Conclusions and clinical relevanceDetomidine caused a longer period of visceral anti–nociception as determined by CRD but a shorter period of anti–nociception as determined by DD than has been previously reported. The lack of somatic anti–nociception as determined by TT testing may be related to the marked decrease in skin temperature, likely caused by peripheral vasoconstriction and the low temperature cut–off of the testing device.  相似文献   
90.
Objective: To compare the partial CO2 rebreathing method (non‐invasive cardiac output [NICO]) and the lithium dilution method (lithium dilution cardiac output [LiDCO]) for cardiac output (CO) measurement in anesthetized dogs. Design: Prospective study. Setting: College of Veterinary Medicine, University of Florida. Animals: Six adult dogs (weight range 22–25.4 kg). Interventions: All animals were instrumented for CO determinations using the LiDCO and NICO methods. Direct blood pressure, heart rate, arterial blood gases, end‐tidal isoflurane (ETI), and CO2 concentrations were monitored throughout the study. CO was manipulated with dobutamine and isoflurane to allow for intermediate, low, and high CO determinations in that order using LiDCO and NICO. Measurements and main results: A 1.5% ETI produced the intermediate rate of CO, a constant‐rate infusion of dobutamine (1–4 μg/kg/min) and 1.1% ETI, the highest rate, and 2.5–3% ETI, the lowest rate. Measurements were obtained in duplicate or triplicate for the LiDCO and continuously for the NICO method after achieving a stable hemodynamic plane for at least 15 minutes at each level of CO, allowing 5 minutes between measurements. Forty‐seven comparisons were determined. The correlation coefficient (r) between the 2 methods was 0.888 for all determinations. The mean LiDCO and NICO from 47 measurements were 155.9±78.7 mL/kg/min (range, 49.6–303.2) and 146.6±62.9 mL/kg/min (50–290.3), respectively. The bias between LiDCO and NICO estimations was 9.3 (?60.7 to +79.4) mL/kg/min (mean and 95% confidence interval). The mean (mL/kg/min) of the differences of LiDCO–NICO was 1.11 × NICO. The relative error was 2.4±24.7%. As CO increased, the relative difference between the methods also increased. Conclusions: The NICO is a viable non‐invasive method for CO determination in the dog and compares well with the LiDCO.  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