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   646篇
  免费   25篇
  国内免费   1篇
林业   37篇
农学   17篇
基础科学   4篇
  64篇
综合类   139篇
农作物   7篇
水产渔业   13篇
畜牧兽医   361篇
园艺   11篇
植物保护   19篇
  2020年   10篇
  2019年   4篇
  2018年   11篇
  2017年   12篇
  2016年   8篇
  2015年   8篇
  2014年   7篇
  2013年   33篇
  2012年   19篇
  2011年   18篇
  2010年   9篇
  2009年   17篇
  2008年   21篇
  2007年   24篇
  2006年   23篇
  2005年   22篇
  2004年   28篇
  2003年   28篇
  2002年   34篇
  2001年   24篇
  2000年   11篇
  1999年   9篇
  1996年   8篇
  1995年   5篇
  1994年   5篇
  1993年   7篇
  1992年   10篇
  1991年   13篇
  1990年   9篇
  1989年   18篇
  1988年   9篇
  1987年   16篇
  1986年   12篇
  1985年   6篇
  1984年   7篇
  1983年   7篇
  1982年   6篇
  1981年   4篇
  1979年   5篇
  1978年   6篇
  1977年   5篇
  1976年   7篇
  1974年   6篇
  1973年   8篇
  1972年   5篇
  1971年   7篇
  1970年   6篇
  1969年   4篇
  1895年   6篇
  1886年   5篇
排序方式: 共有672条查询结果,搜索用时 15 毫秒
21.
22.
This article is designed to aid the practitioner by maximizing the effectiveness of field postmortem diagnostic investigations. Contents include an outline of the procedure for field necropsy of ruminants, recommended tools and supplies, and guidelines for sample collection and submission.  相似文献   
23.
A Combination Chemotherapy Protocol (VELCAP-L) for Dogs with Lymphoma   总被引:3,自引:1,他引:2  
Ninety-eight dogs with lymphoma treated with a 5-drug combination chemotherapy regimen (vincristine, L-asparaginase. cyclophosphamide, doxorubicin, prednisone [VELCAP-L]) were evaluated for pretreatment characteristics predictive for response and remission duration. The complete remission rate was 69%, with a median remission duration of 55 weeks. Dogs with advanced stage of disease, constitutional signs, dogs that were older, and dogs that were dyspneic were less likely to achieve remission. Once in remission, small dogs and dogs without pretreatment thrombocytopenia were likely to have longer remission duration. Toxicoses were frequent, but rarely fatal, and no predictitive factors were found for a dog developing toxicoses. VELCAP-L is an effective treatment for dogs in stage I-III lymphoma, particularly in young, small animals.  相似文献   
24.
25.
26.
Are irregular stands more windfirm?   总被引:3,自引:0,他引:3  
Mason  W.L. 《Forestry》2002,75(4):347-355
  相似文献   
27.
Physical and biological variables affecting juvenile Pacific herring (Clupea pallasi) in Prince William Sound (PWS) from 1995 to 1998 were investigated as part of a multifaceted study of recruitment, the Sound Ecosystem Assessment (SEA) program. Though more herring larvae were retained in eastern PWS bays, ages‐0 and ‐1 herring used bays throughout PWS as nursery areas. Water transported into PWS from the Gulf of Alaska (GOA) contributed oceanic prey species to neritic habitats. Consequently, variations in local food availability resulted in different diets and growth rates of herring among bays. Summer food availability and possible interspecific competition for food in nursery areas affected the autumn nutritional status and juvenile whole body energy content (WBEC), which differed among bays. The WBEC of age‐0 herring in autumn was related to over‐winter survival. The limited amount of food consumption in winter was not sufficient to meet metabolic needs. The smallest age‐0 fish were most at risk of starvation in winter. Autumn WBEC of herring and winter water temperature were used to model over‐winter mortality of age‐0 herring. Differences in feeding and energetics among nursery areas indicated that habitat quality and age‐0 survival were varied among areas and years. These conditions were measured by temperature, zooplankton abundance, size of juvenile herring, diet energy, energy source (GOA vs. neritic zooplankton), WBEC, and within‐bay competition.  相似文献   
28.
29.
  1. Tracking of juvenile sea turtles is a research priority to inform the protection of relevant habitats and ensure sustainable rates of recruitment into adult populations. Based on satellite tracking, mixed stock analysis, and mark–recapture studies, Drini Bay in the South Adriatic Sea, Central Mediterranean, has been confirmed as an important foraging site used by loggerhead turtles from all major rookeries in the Mediterranean subpopulation.
  2. Three juvenile loggerhead turtles (Caretta caretta) from Drini Bay were tracked for 763, 364, and 211 days respectively. All turtles exhibited different movement patterns.
  3. The two smaller turtles ranged widely beyond the bay. One of these (69.5 cm curved‐carapace length; CCL) used the coldest region of the Mediterranean during the first winter of tracking where mean weekly temperatures dipped below 12°C but moved southwards to warmer waters during the second winter. In comparison, the other (66 cm CCL) individual moved south to winter in warmer waters from the outset. Both individuals returned to Drini Bay during summer, demonstrating fidelity to the study site. The third turtle, which was larger (76 cm CCL), remained in Drini Bay for the duration of tracking. These results support the findings of other mark–recapture studies at Drini Bay, which have suggested that the foraging site is being used in a transient way by immature turtles.
  4. All three turtles preferentially used the shallow waters (<30 m) in the south of Drini Bay. The study demonstrates a high degree of overlap between the habitat use of the three tracked turtles and that of adult turtles tracked from nesting sites, and although based on a small sample size, contributes to a growing knowledge base regarding the wider habitat use of the Mediterranean loggerhead population.
  相似文献   
30.
Canine pyoderma     
Bacterial skin disease (or pyoderma) is a common canine disorder. It is usually associated with coagulase-positive staphylococci which multiply on skin and induce disease as a result of a number of poorly understood mechanisms. Pyoderma usually occurs as a result of another underlying disorder. Primary causes include hypersensitivity, ectoparasites and metabolic and immunological disorders. A detailed and systematic investigation is mandatory so that the underlying cause is discovered if possible. A number of cases are idiopathic. Pyodermas may be classified according to depth of infection as this affects the type and duration of therapy required and the prognosis. Deeper forms require more aggressive and prolonged therapy. Management of pyodermas depends on the identification and correction of the underlying cause along with adjunct therapy using systemic and topical antimicrobial agents. Idiopathic cases may require protracted or even lifelong therapy with such medicaments. Glucocorticoids are generally contraindicated in the management of pyoderma.  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