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   890篇
  免费   6篇
林业   30篇
  62篇
综合类   407篇
农作物   14篇
水产渔业   6篇
畜牧兽医   362篇
园艺   2篇
植物保护   13篇
  2012年   43篇
  2011年   54篇
  2010年   6篇
  2008年   40篇
  2007年   47篇
  2006年   52篇
  2005年   50篇
  2004年   53篇
  2003年   52篇
  2002年   48篇
  2001年   31篇
  2000年   31篇
  1999年   22篇
  1995年   12篇
  1994年   9篇
  1993年   11篇
  1992年   8篇
  1991年   6篇
  1990年   10篇
  1989年   6篇
  1988年   11篇
  1987年   5篇
  1986年   9篇
  1985年   11篇
  1984年   12篇
  1983年   8篇
  1982年   10篇
  1981年   7篇
  1980年   8篇
  1979年   8篇
  1976年   12篇
  1974年   5篇
  1970年   10篇
  1969年   6篇
  1968年   8篇
  1966年   5篇
  1963年   10篇
  1960年   5篇
  1958年   5篇
  1957年   10篇
  1955年   7篇
  1954年   8篇
  1953年   7篇
  1948年   5篇
  1947年   6篇
  1946年   4篇
  1945年   6篇
  1928年   4篇
  1924年   5篇
  1922年   4篇
排序方式: 共有896条查询结果,搜索用时 140 毫秒
41.
42.
43.
Mycobacterium fortuitum was isolated in a sample of bronchial fluid collected by transtracheal aspiration from a 1-year-old Corgi dog with a productive cough of 10 days' duration and with radiographic and cytological features of acute suppurative bronchopneumonia. The dog responded favourably to intravenous gentamicin and cephalexin for three days and a six week course of oral ciprofloxacin. Saprophytic mycobacterial pneumonia should be considered in cases of severe pulmonary consolidation in young dogs.  相似文献   
44.
Paracox anticoccidial vaccine was administered to a 7-day-old flock of commercial broiler breeder stock subsequently reared to point-of-lay in the same house. For comparison, three subgroups of another flock of broiler breeders were also vaccinated with Paracox at 7 days of age, reared to 42 days and then transferred to new litter on another farm until point-of-lay. The first subgroup received no further treatment, but the second and third each received a second vaccination with Paracox, either immediately after transfer to the new litter or 42 days after transfer. Using an Eimeria necatrix model, protective immunity was demonstrated by virulent challenge of samples of birds from all groups by the age of 37–40 days (30–33 days after the first vaccination), and was maintained to at least 122–125 days of age, whether the birds remained on the same litter or were transferred to another farm, and whether they received one or two anticoccidial vaccinations. Therefore, there is no disadvantage in transferring birds onto new litter 35 days after a single Paracox vaccination, nor is there any advantage in giving a second vaccination after such a transfer. Vaccinated birds seeded the new litter with oocysts, despite being clinically immune to coccidiosis. A supplementary laboratory experiment showed that birds vaccinated at 8 days of age passed almost no oocysts after a second vaccination at 43 days of age. This indicated that they were not only protected against clinical coccidiosis, but were almost solidly immune to a homologous infection 5 weeks after a single vaccination. Nevertheless, oocysts appeared in the litter of all four groups of commercial breeders throughout the trial, showing that wild-type heterologous infections occurred whether the birds were transferred to new litter or not, but these did not overwhelm the acquired protective immunity and cause clinical coccidiosis.  相似文献   
45.
46.
47.
华山松裸根双月苗造林技术在荒山造林中的应用   总被引:1,自引:0,他引:1  
1989~1993年昆明市万旺林场,采用华山松裸根双月苗成功地营造了980hm2华山松林。本文系统而详尽地介绍了这一实用技术;从造林成活率、保存率及生长状况方面介绍了采用此技术后的效果;对造林成本也作了剖析  相似文献   
48.
OBJECTIVES: To identify the impact of body mass index (BMI) and Western advertising and media on the stage of the nutrition transition among Jordanian women, and to evaluate their impact on eating styles and body image. DESIGN: A randomised cross-sectional survey that included a variety of culturally measured Likert-type scales and body size images. In addition, BMI was calculated based on measured height and weight. SETTING: In the homes of the participants. The data were collected by female interviewers who worked for the Jordan Department of Statistics. SUBJECTS: The sample was based on a random and representative selection of 800 mostly urban Jordanian women. A pre-test sample of 100 women was also used to validate the instruments. RESULTS: Women tended to agree that they ate based on emotional cues. They had high levels of disordered eating attitudes and behaviours and 42.1% were considered restrained eaters. However, these women also had higher than expected body esteem levels and desired a healthy body size. As expected, being obese was associated with a desire to lose weight, being a restrained and emotional eater, and having more disordered eating attitudes and behaviours. Similarly, Western advertising and media were associated with restrained and emotional eating, desired weight loss, and disordered eating attitudes and behaviours. CONCLUSIONS: There is a need to develop health education materials that explain the influence of obesity on health and the negative psychological and physical consequences of restrained and emotional eating, building on the current cultural preferences of healthy body size. Further implications and suggestions for future research are discussed.  相似文献   
49.
50.
胡先马肃与庐山植物园文/汪玉林朱火金袁斌胡先马肃(1895—1968年),江西省南昌市人,是我国享誉世界的著名植物学家。他对植物分类学、古植物学、经济植物学作出了重要贡献。在世界野生植物中,由他确定命名的植物学名称有200多种。早在20年代,他就与我...  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