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   148025篇
  免费   8385篇
  国内免费   228篇
林业   6947篇
农学   4549篇
基础科学   947篇
  18672篇
综合类   25339篇
农作物   5822篇
水产渔业   7509篇
畜牧兽医   75525篇
园艺   1808篇
植物保护   9520篇
  2019年   1435篇
  2018年   2322篇
  2017年   2556篇
  2016年   2379篇
  2015年   1974篇
  2014年   2493篇
  2013年   5685篇
  2012年   4520篇
  2011年   5204篇
  2010年   3368篇
  2009年   3381篇
  2008年   5038篇
  2007年   4756篇
  2006年   4394篇
  2005年   4144篇
  2004年   3934篇
  2003年   4079篇
  2002年   3673篇
  2001年   4293篇
  2000年   4306篇
  1999年   3359篇
  1998年   1345篇
  1997年   1370篇
  1995年   1529篇
  1993年   1350篇
  1992年   2769篇
  1991年   3060篇
  1990年   2923篇
  1989年   2960篇
  1988年   2707篇
  1987年   2729篇
  1986年   2822篇
  1985年   2744篇
  1984年   2231篇
  1983年   1971篇
  1982年   1356篇
  1979年   2135篇
  1978年   1647篇
  1977年   1494篇
  1976年   1349篇
  1975年   1463篇
  1974年   1903篇
  1973年   1941篇
  1972年   1924篇
  1971年   1806篇
  1970年   1759篇
  1969年   1637篇
  1968年   1437篇
  1967年   1526篇
  1966年   1323篇
排序方式: 共有10000条查询结果,搜索用时 734 毫秒
61.
62.
63.
64.
The medical records of 38 horses with puncture wounds of the navicular bursa were reviewed. Only 12 horses had a satisfactory outcome (breeding or riding). Of the remaining 26 horses, 19 were euthanized, five were sold due to persistent severe lameness, one died, and one was lost to long-term follow-up. Different combinations of conservative management prior to surgical debridement and drainage of the navicular bursa were unsuccessful in resolving the condition. Horses that were treated surgically within 1 week of the injury and had a hind leg affected had the best chance of a satisfactory outcome. Additional wound debridement was necessary in 15 horses after initial surgical treatment. The most common complications encountered were navicular bone osteomyelitis and sepsis of the deep digital flexor tendon. Thirteen of 14 horses that had rupture of the deep digital flexor tendon and subluxation of the distal interphalangeal joint had an unsatisfactory outcome. One mare subsequently developed ankylosis of the distal interphalangeal joint and was a useful brood mare. Two horses that had biaxial palmar digital neurectomy because of persistent lameness were later euthanized because of navicular bone fracture and rupture of the deep digital flexor tendon. Results from limited numbers of bacterial cultures and antibiotic sensitivities suggest that penicillin and an aminoglycoside antibiotic should be used as initial antibiotic therapy. Immediate surgical debridement and appropriate antibiotic treatment are recommended as the minimum therapy for penetrating wounds of the navicular bursa in horses.  相似文献   
65.
Prevention of renal carriage of leptospirosis in dogs by vaccination   总被引:1,自引:0,他引:1  
Dogs vaccinated with a Leptospira interrogans vaccine containing serogroups Canicola and Icterohaemorrhagiae and prepared from cultures grown in a protein-free medium resisted challenge with heterologous representatives of these serogroups. In contrast, control dogs were pyrexic and leptospires were isolated from the blood for nine days following Canicola challenge and six days after Icterohaemorrhagiae challenge. Leptospires were isolated from the urine of controls throughout the post challenge period and from kidneys at post mortem examination of six out of six and four out of six Canicola and Icterohaemorrhagiae challenged controls, respectively. There have been no reports of hypersensitivity reactions to this vaccine since its introduction in 1980.  相似文献   
66.
Characterization of monoclonal antibodies directed against swine leukocytes   总被引:3,自引:0,他引:3  
Hybridomas were produced from fusions of the SP2/0 mouse myeloma with splenic cells from: 1) an outbred Sprague Dawley rat immunized with swine peripheral blood mononuclear (PBM) cells; 2) a (CBA/NDub X BALB/c Dub) F1 mouse immunized with concanavalin A (Con A) activated swine PBM cells and 3) a (BALB/c Dub X C3H/He Dub) F1 mouse immunized with swine thymocytes. The resulting supernatants were screened by a microcytotoxicity assay for activity against swine PBM cells. Four hybridomas (MSA1, MSA2, MSA3 and MSA4) were selected, cloned and characterized by their cell reactivity and effect on mitogenic assays. MSA1 and MSA2 belong to the rat IgG2b subclass. MSA3 and MSA4 are of the mouse IgG2a subclass. These monoclonal antibodies reacted in the following manner: MSA1 with monocytes, granulocytes, red blood cells and bone marrow cells; MSA2 with subset of T cells; MSA3 with B cells and subsets of T cells and monocytes (class II molecule) and MSA4, a pan-T cell reagent (E-rosette receptor). The involvement of the various cell types reactive to the different monoclonal antibodies in the mitogenic response of swine PBM cells to Con A, phytohemagglutinin (PHA) or pokeweed mitogen (PWM) was investigated by cellular depletion with monoclonal antibody plus complement. Cellular depletion of PBM cells with the following monoclonal antibodies plus complement treatment resulted in: MSA1, almost total reduction in the mitogenic response to low doses of Con A or PWM; MSA2, partial reduction in the proliferative responses to any concentration of Con A, PHA or PWM; MSA3, partial reduction in proliferative responses to low concentrations of Con A or PWM and 4) MSA4, total elimination of any proliferative response to Con A, PHA or PWM.  相似文献   
67.
Softening process and total antioxidant activity were evaluated in kiwifruit differently exposed to light intensity and harvested at two different times (October 10 and November 14). Fruit was stored for 2 months at 0 °C (S1) and then maintained for a week at ambient temperature (S2). The results showed that fruit harvested later presented a faster softening rate during storage than fruit harvested earlier, even if antioxidant activity did not change. Light-exposed fruit showed higher flesh firmness than that of shaded ones. Polygalacturonase activity was higher in kiwifruit maintained for a week at ambient temperature after cool storage and, in particular the highest value was recorded in fruit harvested later. The behaviour of β-galactosidase was different: it did not show changes in fruit harvested later and significantly decreased in light- and shade-exposed fruit harvested earlier.  相似文献   
68.
69.
70.
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