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   4861篇
  免费   187篇
  国内免费   3篇
林业   245篇
农学   202篇
基础科学   36篇
  745篇
综合类   1268篇
农作物   219篇
水产渔业   309篇
畜牧兽医   1527篇
园艺   110篇
植物保护   390篇
  2023年   22篇
  2022年   21篇
  2021年   61篇
  2020年   73篇
  2019年   94篇
  2018年   91篇
  2017年   83篇
  2016年   91篇
  2015年   65篇
  2014年   85篇
  2013年   183篇
  2012年   259篇
  2011年   339篇
  2010年   188篇
  2009年   145篇
  2008年   331篇
  2007年   337篇
  2006年   376篇
  2005年   321篇
  2004年   331篇
  2003年   304篇
  2002年   302篇
  2001年   58篇
  2000年   35篇
  1999年   48篇
  1998年   50篇
  1997年   28篇
  1996年   36篇
  1995年   36篇
  1994年   30篇
  1993年   36篇
  1992年   31篇
  1991年   31篇
  1990年   29篇
  1989年   36篇
  1988年   27篇
  1987年   32篇
  1986年   21篇
  1985年   27篇
  1984年   32篇
  1983年   25篇
  1982年   23篇
  1981年   26篇
  1980年   23篇
  1979年   15篇
  1978年   17篇
  1977年   18篇
  1976年   19篇
  1975年   16篇
  1974年   24篇
排序方式: 共有5051条查询结果,搜索用时 187 毫秒
151.
The brainstem auditory evoked response (BAER) was recorded from 7 unanesthetized and 27 methoxyflurane anesthetized dogs. A 0.1 msec, 70 dB stimulus delivered at 10 Hz evoked the expected seven wave BAER. Mean peak wave latencies and standard deviations were calculated. Differences were not found between neither right and left ears, nor male and female dogs. The anesthetized dogs had a significantly longer latency for all waves, except wave I, than the unanesthetized dogs. Use of the BAER as a diagnostic technique for brainstem lesions is recommended.Publication No. 1702, School of Veterinary Medicine, Auburn University, AL 36849, USA  相似文献   
152.
A biological simulation model and a linear programming model were interfaced to determine production efficiencies and the optimal carrying capacity of a cow-calf producer in East Texas and to compare net returns to the model farm, given alternative tame forage systems and management practices. Experimental data both on forage systems and on livestock were used to verify and validate the simulated herds. The results showed that (1) of the three tame forage systems analyzed, warm-season perennial forages provided a relatively higher carrying capacity/ha, whereas a mix of both warm- and cool-season forages that allows year-round grazing gave relatively higher net returns/ha to management; (2) nutritional stress during winter months decreased animal performance proportionately more than it decreased feed costs; and (3) although spring-calving herds included more animals than corresponding fall-calving herds on the same land area, fall-calving herds produced more liveweight sales and generally higher net returns.  相似文献   
153.
154.
Blood glycosylated hemoglobin (GHb) concentration was quantified in 84 healthy cats, 9 cats with stress-induced hyperglycemia, 37 cats with newly diagnosed diabetes mellitus, and 122 diabetic cats treated with insulin or glipizide. Diabetic control was classified as good or poor in insulin-treated or glipizide-treated cats based on review of history, physical examination findings, changes in body weight, and measurement of blood glucose concentrations. Blood GHb concentration was determined using an affinity chromatography assay. Mean blood GHb concentration was similar for healthy normoglycemic cats and cats with transient, stress-induced hyperglycemia, but was significantly (P < .001) higher in untreated diabetic cats when compared with healthy normoglycemic cats. Mean blood GHb concentration was significantly (P < .001) higher in 84 cats with poorly controlled diabetes mellitus when compared with 38 cats in which the disease was well controlled. Mean blood GHb concentration decreased significantly (P < .01) in 6 cats with untreated diabetes mellitus after insulin and dietary treatment. A similar significant (P < .01) decrease in mean blood GHb concentration occurred in 7 cats with poorly controlled diabetes mellitus after diabetic control was improved by an increase in insulin dosage from 1.1 ± 0.9 to 1.4 ± 0.6 U/kg/ 24 h and by feeding a diet containing increased fiber content and in 6 cats with transient diabetes mellitus 8.2 ± 0.6 weeks after discontinuing insulin treatment. There was a significant (P< .01) stress-induced increase in mean fasting blood glucose concentration and mean blood glucose concentration for 12 hours after administration of insulin or glipizide but no change in mean blood GHb concentration in 5 docile diabetic cats 12.2 ± 0.4 weeks after the cats became fractious as a result of frequent hospitalizations and blood samplings. Results of this study suggest that evaluation of blood GHb concentration may be a clinically useful tool for monitoring glycemic control of diabetes in cats.  相似文献   
155.
156.
Ohne Zusammenfassung  相似文献   
157.
158.
159.
160.
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