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   378篇
  免费   33篇
林业   26篇
农学   12篇
基础科学   4篇
  45篇
综合类   31篇
农作物   23篇
水产渔业   17篇
畜牧兽医   221篇
园艺   7篇
植物保护   25篇
  2023年   5篇
  2022年   3篇
  2021年   4篇
  2020年   6篇
  2019年   9篇
  2018年   10篇
  2017年   11篇
  2016年   8篇
  2015年   12篇
  2014年   4篇
  2013年   18篇
  2012年   17篇
  2011年   23篇
  2010年   12篇
  2009年   12篇
  2008年   20篇
  2007年   16篇
  2006年   15篇
  2005年   15篇
  2004年   13篇
  2003年   29篇
  2002年   6篇
  2001年   7篇
  2000年   7篇
  1999年   6篇
  1998年   6篇
  1997年   5篇
  1994年   3篇
  1993年   5篇
  1992年   5篇
  1991年   5篇
  1990年   7篇
  1989年   5篇
  1988年   5篇
  1987年   4篇
  1986年   6篇
  1979年   3篇
  1976年   5篇
  1974年   5篇
  1972年   2篇
  1970年   4篇
  1969年   4篇
  1968年   4篇
  1967年   2篇
  1966年   4篇
  1965年   3篇
  1962年   3篇
  1924年   2篇
  1887年   1篇
  1881年   1篇
排序方式: 共有411条查询结果,搜索用时 15 毫秒
81.
This review assesses the efficacy of whole cell Tritrichomonas foetus vaccine to prevent and treat trichomoniasis in beef cattle. Three databases were searched in June 2012. Eligible studies compared infection risk, open risk, and abortion risk in heifers or infection risk in bulls that received vaccine compared with no vaccine. Study results were extracted, summary effect measures were calculated, and the quality of the evidence was assessed. From 334 citations identified, 10 were relevant to the review . For heifers, there was limited evidence of moderate quality to assess the impact of vaccination on infection risk (RR, 0.89; P = .16; 95% CI, 0.76–1.05; 6 randomized and 4 nonrandomized studies; 251 animals) and open risk (RR, 0.80; P = .06; 95% CI, 0.63–1.01; 6 randomized and 5 nonrandomized studies; 570 animals). The quality of the body of work describing the impact of vaccination on abortion risk was low (summary RR, 0.57; P = .0003; 95% CI, 0.42–0.78; 3 randomized and 2 nonrandomized studies; 176 animals). The quality of evidence was very low for duration of infection (mean difference, ?23.42; P = .003; 95% CI, ?38.36 to ?7.85; 2 randomized and 3 nonrandomized studies; 163 animals). Although the summary effect measures suggest a benefit to vaccination, due to publication bias the effect reported here is likely an over estimate of efficacy. For bull‐associated outcomes, the evidence base was low or very low quality.  相似文献   
82.
83.
84.
Parasitic zoonoses are common and widely distributed in the Southeast Asian region. However, the interactions between parasites, hosts and vectors are influenced by environmental, socio-cultural and livestock production changes that impact on the distribution, prevalence and severity of disease. In this review we provide an update on new knowledge in the context of ongoing changes for the food-borne pig associated zoonoses Taenia solium and Trichinella spp., the food-borne trematodes Opisthorchis viverrini and Clonorchis sinensis, the water-borne trematodes Schistosoma spp., the vector-borne zoonotic protozoa Plasmodium knowlesi and Leishmania spp. and the soil-borne zoonotic hookworm Ancylostoma ceylanicum. These various changes need to be considered when assessing or developing regional control programs or devising new research initiatives in a changing SE Asia.  相似文献   
85.
86.
Bovine interferon-alpha I1 (bIFN-alpha) may be useful for enhancing fertility in sheep and cattle because it has extensive sequence homology with ovine and bovine trophoblast protein-1 and, like those proteins, extends corpus luteum lifespan. To test the effectiveness of bIFN-alpha to enhance fertility, several experiments were performed in which inseminated heifers were given i.m. injections of bIFN-alpha approximately at the time of embryo-mediated signals that result in maintenance of the corpus luteum. In Exp. 1, heifers given 20 mg of bIFN-alpha daily from d 14 to 17 tended (P less than .07) to have lower pregnancy rates at d 110 to 112 of gestation (36/75; 48% vs 43/72; 60%). Similar results were obtained in Exp. 2 when heifers received a single injection of 40 mg of bIFN-alpha or placebo at d 13 after estrus; pregnancy rates at d 42 were 39/104 (38%) for bIFN-alpha and 47/98 (48%) for placebo. In Exp. 3, heifers were given gradually increasing doses of bIFN-alpha or placebo from d 11 to 19, because such a regimen had been shown to reduce the number of heifers experiencing hyperthermia after bIFN-alpha injection. Pregnancy rates were 42/95 (44%) for bIFN-alpha and 62/111 (56%) for placebo. Across all three experiments, pregnancy rates were lower (P less than .01) for heifers treated with bIFN-alpha (117/274; 43%) than for heifers treated with placebo (152/281; 54%). In conclusion, these results demonstrate that, under the administration systems used, bIFN-alpha does not increase pregnancy rate, but rather tends to reduce it.  相似文献   
87.
OBJECTIVE: To conduct serologic surveillance for Leishmania spp in English foxhounds from a kennel, as well as recipients of blood from these dogs, and determine whether L infantum organisms could be transmitted via blood transfusion. DESIGN: Serologic prevalence survey. ANIMALS: 120 English foxhounds and 51 dogs of various breeds receiving blood from these donors. PROCEDURE: Foxhound blood donors, foxhound nondonors, and nonfoxhound blood recipient dogs were evaluated serologically for Leishmania spp by indirect fluorescent antibody testing. Dogs that received packed RBC (PRBC) transfusions from foxhound donors from mid-1996 through mid-2000 were identified. Furthermore, dogs were serologically evaluated if they had received fresh frozen plasma (FFP) transfusions in 1999 and 2000 from seropositive foxhound blood donors. RESULTS: Thirty percent of the English Foxhounds were seropositive for Leishmania spp (titer > or = 1:16), although the degree of seropositivity varied considerably during the period. Furthermore, 57 foxhounds had been used as donors from 1996 to 2000, and 342 units of PRBC had been transfused to at least 227 patients. All 25 dogs screened that received PRBC from seronegative foxhound donors tested negative, whereas 3 of 7 dogs that received PRBC from seropositive donors tested positive. All 9 dogs that received FFP from seropositive foxhound donors remained seronegative. CONCLUSIONS AND CLINICAL RELEVANCE: To our knowledge, this report documents the first transmission of Leishmania spp by blood transfusion. The use of foxhounds as blood donors may not be advisable in North America.  相似文献   
88.

Background

There is lack of data on idiopathic epilepsy (IE) in the Italian Spinone (IS).

Objectives

To estimate the prevalence of IE in the IS in the United Kingdom (UK) and to investigate predictors of survival and seizure remission.

Animals

The target population consisted of 3331 IS born between 2000 and 2011 and registered with the UK Kennel Club (KC). The owners of 1192 dogs returned phase I questionnaire. Sixty‐three IS had IE.

Methods

Population survey. The owners of all UK KC‐registered IS were invited to complete the phase I questionnaire. Information from the phase I questionnaire and veterinary medical records was used to identify IS with IE and obtain data on treatment and survival. Additional information was obtained from owners of epileptic IS who completed the phase II questionnaire.

Results

The prevalence of IE in the IS in the UK was estimated as 5.3% (95% CI, 4.03–6.57%). Survival time was significantly shorter in IS euthanized because of poorly controlled IE compared with epileptic IS that died of unrelated disorders (P = 0.001). Survival was significantly longer in IS with no cluster seizures (CS) (P = 0.040) and in IS in which antiepileptic medication was initiated after the second seizure rather than after ≥3 seizures (P = 0.044). Seizure remission occurred only in 3 IS.

Conclusions and Clinical Importance

The prevalence of IE in IS (5.3%) is higher than in dogs (0.6%) in the UK. Idiopathic epilepsy in IS has a severe phenotype. Antiepileptic medication initiation after the second seizure and aggressive treatment of CS may improve survival.  相似文献   
89.
Objective: To determine the cardiovascular effects of desflurane in dogs following acute hemorrhage. Design: Experimental study. Animals: Eight mix breed dogs. Interventions: Hemorrhage was induced by withdrawal of blood until mean arterial pressure (MAP) dropped to 60 mmHg in conscious dogs. Blood pressure was maintained at 60 mmHg for 1 hour by further removal or replacement of blood. Desflurane was delivered by facemask until endotracheal intubation could be performed and a desflurane expiratory end‐tidal concentration of 10.5 V% was maintained. Measurements and main results: Systolic, diastolic, and mean arterial blood pressure (SAP, DAP and MAP), central venous pressure (CVP), cardiac output (CO), stroke volume (SV), cardiac index (CI), systemic vascular resistance (SVR), heart rate (HR), respiratory rate (RR), partial pressure of carbon dioxide in arterial blood (PaCO2), and arterial pH were recorded before and 60 minutes after hemorrhage, and 5, 15, 30, 45 and 60 minutes after intubation. Sixty minutes after hemorrhage, SAP, DAP, MAP, CVP, CO, CI, SV, PaCO2, and arterial pH decreased, and HR and RR increased when compared with baselines values. Immediately after intubation, MAP and arterial pH decreased, and PaCO2 increased. Fifteen minutes after intubation SAP, DAP, MAP, arterial pH, and SVR decreased. At 30 and 45 minutes, MAP and DAP remained decreased and PaCO2 increased, compared with values measured after hemorrhage. Arterial pH increased after 30 minutes of desflurane administration compared with values measured 5 minutes after intubation. Conclusions: Desflurane induced significant changes in blood pressure and arterial pH when administered to dogs following acute hemorrhage.  相似文献   
90.
Twenty-four barrows (approximately 25 kg initial wt) were used in each of three 2 X 2 factorially arranged trials to study effects of exercise (not exercised vs walking 30 min/d, 6 d/wk on a treadmill) and diet (low energy vs high energy) on performance during the growing-finishing period. Average daily gain (ADG) of barrows not exercised was greater (P less than .07) than that of those exercised. Barrows fed the high-energy diet had greater (P less than .05) ADG, lower (P less than .01) feed intake and lower (P less than .01) feed-to-gain ratio than barrows fed low-energy diets. In trials 1 and 2, pigs were slaughtered when removed from test and selected carcass measurements and internal organ weights were obtained. Exercise did not significantly affect carcass length, backfat thickness, loin muscle area or lean cuts (as a percentage of off-test weight). Pigs fed the high-energy diet had more (P less than .01) backfat than those fed the low-energy diet. Neither the exercise program nor the diet had a significant effect on organ weights. Pigs not exercised had a higher (P less than .05) plasma albumin-to-globulin ratio and lower (P less than .05) plasma creatinine concentration than did pigs that were exercised. Also, pigs not exercised had slightly higher (P less than .08) plasma albumin and glucose, but lower (P less than .06) plasma globulin levels.(ABSTRACT TRUNCATED AT 250 WORDS)  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