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   66篇
  免费   45篇
林业   5篇
综合类   6篇
农作物   1篇
畜牧兽医   97篇
园艺   1篇
植物保护   1篇
  2021年   1篇
  2020年   2篇
  2019年   2篇
  2018年   1篇
  2017年   1篇
  2016年   3篇
  2015年   1篇
  2014年   1篇
  2013年   2篇
  2012年   3篇
  2011年   3篇
  2010年   2篇
  2004年   1篇
  2003年   2篇
  2002年   1篇
  2001年   7篇
  2000年   7篇
  1999年   6篇
  1998年   4篇
  1997年   1篇
  1996年   1篇
  1994年   1篇
  1993年   2篇
  1992年   6篇
  1991年   5篇
  1990年   1篇
  1989年   1篇
  1988年   8篇
  1987年   11篇
  1986年   3篇
  1985年   4篇
  1984年   2篇
  1983年   1篇
  1980年   1篇
  1979年   1篇
  1976年   1篇
  1975年   2篇
  1972年   2篇
  1971年   2篇
  1970年   1篇
  1969年   2篇
  1968年   1篇
  1959年   1篇
排序方式: 共有111条查询结果,搜索用时 15 毫秒
51.
A healthy adult, intact female keeled box turtle (Cuora mouhotii) was found to have a marked heterophilic leukocytosis using normal hematologic parameters established for the eastern box turtle (Terrapene carolina carolina), a related chelonian species. This animal was monitored with serial complete blood counts (CBCs) over the next 15 years despite remaining asymptomatic for an infectious condition. Retrospective CBC data were compiled from 38 presumably healthy keeled box turtles to establish hematologic values for comparison in this species. Using this species-specific data, over the 15-year period, the female keeled box turtle had two times where the white blood cell (WBC) count was greater than 2 standard deviations (SD) above the mean, six times where the WBC count was greater than 1 SD above the mean, six times where the PCV was greater than 2 SD above the mean, and eight times where the PCV was greater than 1 SD above the mean. Infection and inflammation are the most common causes of leukocytosis in reptiles; however, given the clinical presentation of this patient, it was postulated that these clinicopathologic changes could be secondary to a stress response. Establishing reference intervals and understanding how stress impacts CBC parameters are important for evaluating the health status of keeled box turtles kept in captivity and for assessing the effects of environmental changes on the health status of wild populations of this endangered chelonian species.  相似文献   
52.
Radiative climate forcing by the mount pinatubo eruption   总被引:2,自引:0,他引:2  
Radiative flux anomalies derived from the National Aeronautics and Space Administration (NASA) spaceborne Earth Radiation Budget Experiment were used to determine the volcanic radiative forcing that followed the eruption of Mount Pinatubo in June 1991. They are the first unambiguous, direct measurements of large-scale volcanic forcing. The volcanic aerosols caused a strong cooling effect immediately; the amount of cooling increased through September 1991 as shortwave forcing increased relative to the longwave forcing. The primary effects of the aerosols were a direct increase in albedo over mostly clear areas and both direct and indirect increases in the albedo of cloudy areas.  相似文献   
53.
54.
Increasing irrigation efficiency and reducing groundwater contamination from agricultural and nursery runoff are important components in environmentally compatible plant production practices. The objectives of this study were to quantify mineral leaching from containerized (2+0) white spruce seedlings grown under three different irrigation regimes (30, 40 and 55% V/V) and to determine the effect of irrigation regime on growth, nutritional status, and gas exchange. To negate the effect of environmental variables, a completely randomized block experiment was installed in a normal production run of air-slit containerized white spruce seedlings grown under an unheated polyethylene tunnel. Whereas substrate water content was monitored daily, biweekly measurements of tissue and substrate fertility and seedling morphophysiological variables were made over the course of the growing season. Leaching of mineral nutrients was continuously monitored throughout the experimental period. Reducing volumetric substrate water content from 55 to 30% did not have a significant effect on seedling growth, carbon allocation, tissue nitrogen content, or end-of-season morphology. This irrigation strategy also resulted in a 20% reduction in water usage and, more importantly, reduced the total leachate volume by 65% and the quantity of N leached by 52%. Maintaining rhizosphere water content of (2+0) white spruce seedlings at 40% V/V compromises neither plant growth nor physiological processes. This strategy limits leaching of water and mineral nutrients, and reduces the risk of groundwater contamination, thus enabling growers to meet both quality and environmental standards for seedlings grown in northern forest nurseries.  相似文献   
55.
56.
The ameliorating effects of Cu++ and SO4--ions on concurrent selenite toxicity were compared in two factorial experiments using 60 weanling rats each. In the first experiment, 0, 500 and 1,000 mg Cu (as CuCl2)/kg diet were fed in conjunction with 0, 5, 10 and 20 mg Se (as Na2SeO3)/kg diet. In the second experiment, the treatments were 0, 500 and 1,000 mg SO4 (as Na2SO4)/kg fed in conjunction with 0, 5, 10 and 20 mg Se/kg diet. A paired-feeding experiment using 10, 15 and 20 mg Se/kg diet was also conducted with 28 rats to compare the influence of inanition in control and selenite-fed rats. Cupric++ ion, but not SO4--ion, prevented mortality among selenite-intoxicated rats. There were significant Cu X Se interaction effects on feed intake, daily gain, packed cell volume (PCV), serum Cu and Fe, sperm counts, and weights of liver, kidney and testis. There were main effects of Cu and Se on serum Se and liver Cu. In Exp. 2 there were significant SO4 X Se interaction effects on feed intake, daily gain, serum Cu and testis weight. There were main effects of Se on PCV, sperm count, serum testosterone, liver Se, liver Cu and the absolute weights of liver and kidney. The only main effect of SO4 was that of increased liver Cu concentrations. Among the pair-fed rats, the selenite-fed rats, with one exception, died before their paired rats.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
57.
Inductively coupled argon plasma spectroscopy was used to generate multielement profiles of bovine serum (n = 607), liver (n = 229), and kidney (n = 90) samples submitted to the Animal Health Diagnostic Laboratory at Michigan State University, East Lansing. The presented frequency distribution histograms of element concentrations in the different samples provided a data base for diagnostic interpretations and illustrated some of the advantages, as well as limitations, of inductively coupled argon plasma for this purpose.  相似文献   
58.
59.
60.
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