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   171篇
  免费   21篇
林业   16篇
农学   4篇
  24篇
综合类   35篇
农作物   6篇
水产渔业   24篇
畜牧兽医   73篇
园艺   1篇
植物保护   9篇
  2022年   2篇
  2021年   4篇
  2019年   4篇
  2018年   2篇
  2017年   4篇
  2016年   7篇
  2015年   12篇
  2014年   7篇
  2013年   2篇
  2012年   4篇
  2011年   8篇
  2010年   5篇
  2009年   4篇
  2008年   4篇
  2007年   4篇
  2006年   10篇
  2005年   3篇
  2004年   8篇
  2003年   5篇
  2002年   2篇
  2001年   7篇
  2000年   6篇
  1999年   2篇
  1998年   3篇
  1997年   2篇
  1996年   4篇
  1995年   3篇
  1994年   2篇
  1991年   2篇
  1987年   4篇
  1983年   2篇
  1977年   3篇
  1976年   3篇
  1975年   3篇
  1973年   4篇
  1972年   4篇
  1971年   3篇
  1970年   3篇
  1969年   2篇
  1968年   4篇
  1966年   1篇
  1965年   2篇
  1964年   3篇
  1963年   1篇
  1959年   1篇
  1957年   1篇
  1952年   1篇
  1945年   1篇
  1940年   1篇
  1936年   1篇
排序方式: 共有192条查询结果,搜索用时 93 毫秒
41.
42.
OBJECTIVE: To estimate West Nile virus (WNV) infection rates, assess environmental variables that correlated with seropositivity in dogs and cats, and assess whether pets should be considered as possible sentinels for WNV and therefore of potential human exposure. DESIGN: Cross-sectional serosurvey. ANIMALS: 442 dogs and 138 cats. PROCEDURE: Serum samples were screened for seropositivity against WNV by use of the plaque reduction neutralization test. RESULTS: 116 (26%) dogs and 13 (9%) cats yielded positive results. The odds of seropositivity against WNV for outdoor-only family dogs were almost 19 times as great as those for indoor-only family dogs and almost twice as great for stray dogs as for family dogs. Family dogs not receiving heartworm medication were 2.5 times as likely to yield positive results for antibodies against WNV as family dogs receiving heartworm medication. CONCLUSIONS AND CLINICAL RELEVANCE: Seropositivity was greater for outdoor family dogs than for indoor family dogs. Further investigation of the potential use of stray dogs as sentinel indicators for WNV infection and the potential risk of human exposure is warranted.  相似文献   
43.
Two 112-d studies were conducted to evaluate effects of the deaminase inhibitor, 4,4'-dimethyldiphenyliodonium chloride, on performance of growing cattle. With diets containing low levels of crude protein (i.e., 11%), 25 ppm of chemical in the diet increased (P less than .05) gain and improved (P less than .05) feed efficiency. Feed intake was not affected. Higher levels of chemical (50 and 100 ppm) produced equivalent responses. With a higher level of dietary crude protein (i.e., 14%) gain and feed efficiency were not improved and some decreases in feed intake were observed. Performance responses resulting from adjustments in ruminal nitrogen transactions to provide more alpha-amino-N depend upon whether the animal needs additional amino acids for maintenance and production. Our data demonstrated that the supply of amino acids can be increased either by adjustment of ruminal nitrogen transactions with a chemical agent or by increasing concentration of dietary protein.  相似文献   
44.
A province-wide, cross-sectional seroprevalence and agroecological risk factor study of Mycobacterium avium subspecies paratuberculosis (MAP), Neospora caninum (NC), Bovine leukemia virus (BLV), and Bovine viral diarrhea virus (BVDv) genotypes 1 and 2 (BVDv1 and BVDv2) infection in dairy cattle herds in Alberta was conducted. Among adults, the seroprevalence of MAP, NC, and BLV was 9.1%, 18.5%, and 26.9%, respectively. For MAP, based on a herd test cutpoint of 2 or more seropositive cows, 58.8% of herds were infected. Herd-level seroprevalence for NC and BLV was 98.7% and 86.7%, respectively, based on a herd-test cutpoint of 1 seropositive cow. Among unvaccinated dairy heifers, the seroprevalence for BVDv1 and BVDv2 infection was 28.4% and 8.9%, respectively, while herd-level infection was 53.4% and 19.7%. Seroprevalence for MAP varied moderately by agroecological region, whereas that for NC, BLV, and BVDv1 and BVDv2 did not. For MAP, aridity and soil pH (correlated features of the region) were also important.  相似文献   
45.
An indirect enzyme-linked immunosorbent assay (IELISA) was developed for the detection of equine serum antibodies to lipopolysaccharide of Salmonella enterica subsp. enterica serovar Abortusequi (LPS), a causative organism of Equine Paratyphoid. The data presented demonstrates that horses immunized with S. abortusequi LPS developed antibodies detectable by the IELISA. By comparison, the tube agglutination test (TAT) did not detect antibody to S. abortusequi LPS as consistently as the IELISA. The data suggests that the IELISA may be a more suitable test for the detection of serum antibodies to S. abortusequi than the TAT.  相似文献   
46.
47.
A spinal cord lesion localised caudal to the L6 spinal segment was diagnosed in a 2-year-old female spayed domestic longhair cat with acute onset paraparesis. Magnetic resonance imaging findings were consistent with an acute, non-compressive nucleus pulposus extrusion of the L5-L6 intervertebral disc. The cat was successfully managed with supportive care, including cage confinement.  相似文献   
48.
This study was undertaken to evaluate the lipidemic response of rice bran and the possible enhancement of its healthful properties by using raw or processed white or brown rice in place of corn starch. All diets contained 10% total dietary fiber, 15% fat, and 0.5% cholesterol. Weanling male golden Syrian hamsters were fed cellulose control (CC), processed corn starch (PCS), cellulose with processed brown rice (CPBR), rice bran (RB), RB with white rice (RBWR), RB with processed white rice (RBPWR), RB with brown rice (RBBR), and RB with processed brown rice (RBPBR) diets. After three weeks, the PCS diet significantly lowered total plasma cholesterol (TC) compared with the CC, CPBR, RBWR, and RBPBR diets. RB and RBBR diets significantly lowered TC and LDL‐C compared with CPBR diet. All the RB‐containing and PCS diets significantly lowered liver cholesterol and liver lipid content. Processing white rice increased TDF content 240% and insoluble dietary fiber (IDF) 360%, whereas soluble dietary fiber (SDF) decreased by 25%. Uncooked brown rice contained 7 times as much TDF as uncooked white rice. Processing brown rice decreased its TDF, IDF and SDF contents by 12, 6, and 42%, respectively. The data suggest that a possible mechanism for cholesterol‐lowering by rice bran, with or without added raw or processed rice (white or brown), is by decreasing lipid digestibility and increasing neutral sterol excretion, whereas cholesterol‐lowering by processed corn starch is mediated through other mechanisms.  相似文献   
49.
Brans from rice, oats, corn, and wheat were cooked in a twin-screw extruder at either high or low energy input, and their cholesterol-lowering effects were compared with those of unprocessed brans when fed to four-week-old male golden Syrian hamsters (n = 10 per treatment) for three weeks. Peanut oil was added to oat, corn, and wheat bran during the extrusion process to match the oil content of rice bran. Diets contained 10% total dietary fiber, 10.3% fat, 3% nitrogen, and 0.3% cholesterol. Plasma and liver cholesterol and total liver lipids were significantly lower with low-energy extruded wheat bran compared with unprocessed wheat bran. Extrusion did not alter the hypocholesterolemic effects of rice, oat, or corn brans. Plasma and liver cholesterol levels with corn bran were similar to those with oat bran. Relative cholesterol-lowering effects of the brans, determined with pooled (extruded and unextruded) bran data, were rice bran > oat bran > corn bran > wheat bran. Rice bran diets resulted in significantly lower levels of total plasma cholesterol and very low density lipoprotein cholesterol compared with all other brans. Total liver cholesterol and liver cholesterol concentrations (mg/g) were significantly lower with high-energy extruded rice bran compared with the cellulose control group. Plasma cholesterol and total liver cholesterol values with low-energy extruded wheat bran were similar to those with rice bran (unextruded or extruded) diets. Lowered cholesterol with rice bran diets may result in part from greater lipid and sterol excretion with these diets. Results with low-energy extruded wheat bran suggest that this type of processing may improve the potential for lowering cholesterol with wheat bran products.  相似文献   
50.
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