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   206篇
  免费   0篇
林业   2篇
农学   43篇
  1篇
水产渔业   18篇
畜牧兽医   132篇
植物保护   10篇
  2012年   2篇
  2011年   5篇
  2010年   9篇
  2009年   15篇
  2008年   6篇
  2007年   3篇
  2006年   3篇
  2005年   2篇
  2004年   2篇
  2003年   1篇
  2002年   1篇
  1998年   5篇
  1997年   9篇
  1996年   4篇
  1995年   8篇
  1994年   10篇
  1993年   10篇
  1992年   9篇
  1991年   10篇
  1990年   17篇
  1989年   5篇
  1988年   5篇
  1987年   5篇
  1986年   10篇
  1985年   5篇
  1984年   4篇
  1983年   2篇
  1982年   2篇
  1981年   3篇
  1980年   2篇
  1979年   6篇
  1978年   4篇
  1977年   2篇
  1976年   4篇
  1975年   3篇
  1974年   3篇
  1972年   3篇
  1971年   1篇
  1970年   3篇
  1966年   1篇
  1954年   1篇
  1952年   1篇
排序方式: 共有206条查询结果,搜索用时 15 毫秒
31.
The effects of migrating seniors on the provision of local public services in rural communities is growing in importance because of the large number of retiring baby boomers and the increasing rate at which these retirees are locating outside traditional retirement destinations. Some communities are optimistic about attracting and retaining retirees as an economic development strategy, but others are concerned that inmigrating seniors may be reluctant to support local public services, such as education, bringing with them “Gray Peril.” This article attempts to clarify questions regarding the Gray Peril hypothesis and local ability and willingness to fund education in Tennessee, an increasingly popular retirement destination. To this end, county per pupil education expenditure growth is explained by growth trends in local property tax assessment and sales tax revenue, and migration patterns of the retirement‐aged population from 1962 to 2002.  相似文献   
32.
33.
Administration of iodinated contrast medium interferes with iodide uptake in the human thyroid gland and compromises diagnostic thyroid scintigraphy and radioiodine treatment for 4–6 weeks. However, the degree and duration of inhibition of thyroid uptake of pertechnetate (99mTcO4?) by iodinated contrast medium has not been established in any species. The main objective of this study was to better understand the temporal characteristics and magnitude of inhibition of feline thyroid uptake of 99mTcO4? due to iohexol administration. Routine thyroid scintigraphy was performed in eight cats by intravenous (IV) injection of 185 MBq (5 mCi) of 99mTcO4? both 4 days before and 0,1, 3, 7,14, and 28 days after IV administration of 880 mg I/kg iohexol (240 mg I/ml). Thyroid scintigraphy data were used to calculate thyroid:salivary gland ratios (T:S) and the percentage of total injected 99mTcO4? dose uptake within the thyroid (%TU) at 20 min postinjection. After iohexol administration, mean T:S was significantly decreased below baseline only on day 1. At no point during the study did any cat have a T:S that fell below the published normal reference range of 0.71±0.14. There was a significant decrease in %TU on day 1, 3, and 14; however, at no point during the study, did any cat have a %TU that fell below the published normal reference ranges of 0.64±0.57, 0.68±0.9, or 0.75±1.38.  相似文献   
34.
35.
36.
37.
38.
The paper considers briefly the history of the use of timberunderground and the general problem of support and goes on todiscuss the two main uses for timber in mining, i.e. on roadwaysand at the coal face, where the two principal methods of workingare pillar and stall working and longwall working. Species whosetimber is useful for supports are listed and the various kindsof supports given together with the chief factors affectingtheir behaviour. Replacement of timber by steel is discussed,and in considering the outlook for home-grown timber props emphasisis laid on the need to supply only the best types properly preparedand seasoned.  相似文献   
39.
Résumé— Un épithélioma spinocellulaire s'est développé sur des lésions chroniques incontrôlées de lupus erythémateux discoïde chez deux chiens bergers allemands. Les chiens n'avaient reçu ni traitement ni photoprotection pour leurs lésions de lupus discoïde durant les 4 à 6 ans précédant l'apparition clinique d'épithéliomas spinocellulaires. [Scott, D.W., Miller, W.H., Jr. Squamous cell carcinoma arising in chronic discoid lupus erythematosus nasal lesions in two German Shepherd Dogs (Un épithélioma spinocellulaire suivenant sur des lesions de lupus erythémateux discoïde chroniques chez deux bergers allemands).
Resumen— Dos perros de raza Pastor Alemán desarrollaron carcinomas de células escamosas en lesiones crónicas del tipo lupus eritematoso discoide. Estos animales no habian recibido tratamiento ni protección solar del cuadro de lupus eritematoso discoide en los 4 a 6 años previos al desarrollo del carcinoma escamoso. [Scott, D.W., Miller, W.H., Jr. Squamous cell carcinoma arising in chronic discoid lupus erythematosus nasal lesions in two German Shepherd Dogs (Carcinoma de células escamosas a partir de lesiones crónicas nasales del tipo lupus eritematoso discoide en dos perros Pastor Alemán).
Abstract— Squamous cell carcinoma developed in the chronic, uncontrolled nasal lesions of discoid lupus erythematosus in two German Shepherd Dogs. The dogs had received no treatment nor photoprotection for their discoid lupus erythematosus for 4–6 years prior to the clinical onset of squamous cell carcinoma.  相似文献   
40.
First-pass nuclear angiocardiography was performed on 13 normal horses and 5 horses with confirmed left-to-right ventricular septal defects. Two methods of analyzing the ensuing pulmonary time-activity histograms for shunt recirculation through the lungs were evaluated: (1) pulmonary-to-systemic blood flow ratio (QP:QS), based on gamma variate modeling of the lung histogram, and (2) a simple count-ratio method (C2:C1). Normal values were QP:QS=1.17±0.04 and C2:C1=0.40±0.07. Values for the five horses with left-to-right shunts were QP:QS=2.94±0.13 and C2:C1=0.76±0.11. Both parameters showed significant differences (unpaired t -test; p <0.005) between the two groups, although separation was better with QP:QS.  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