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   456篇
  免费   43篇
林业   9篇
农学   39篇
基础科学   3篇
  33篇
综合类   87篇
农作物   16篇
水产渔业   17篇
畜牧兽医   267篇
园艺   1篇
植物保护   27篇
  2022年   4篇
  2021年   4篇
  2020年   18篇
  2019年   11篇
  2018年   9篇
  2017年   13篇
  2016年   11篇
  2015年   7篇
  2014年   10篇
  2013年   14篇
  2012年   17篇
  2011年   30篇
  2010年   14篇
  2009年   14篇
  2008年   19篇
  2007年   21篇
  2006年   19篇
  2005年   13篇
  2004年   16篇
  2003年   7篇
  2002年   8篇
  2001年   7篇
  2000年   9篇
  1999年   14篇
  1998年   6篇
  1997年   6篇
  1996年   6篇
  1993年   4篇
  1992年   10篇
  1991年   5篇
  1989年   5篇
  1988年   5篇
  1987年   7篇
  1986年   4篇
  1985年   5篇
  1984年   12篇
  1983年   7篇
  1982年   7篇
  1980年   3篇
  1979年   8篇
  1978年   5篇
  1977年   4篇
  1975年   8篇
  1974年   5篇
  1973年   3篇
  1972年   5篇
  1970年   6篇
  1968年   4篇
  1967年   4篇
  1966年   5篇
排序方式: 共有499条查询结果,搜索用时 296 毫秒
51.
Prognostic factors for feline mammary tumors   总被引:1,自引:0,他引:1  
The case records of 100 cats with malignant mammary tumors were reviewed. All cats were staged clinically according to the staging system of the World Health Organization. The following information was obtained from the medical records: age at time of diagnosis, breed, tumor size, date of surgery, type of surgical procedure performed, histologic type of tumor, disease-free interval, survival time, and cause of death. Factors of no prognostic value were age (less than or equal to 10 years vs greater than 10 years) and breed. Tumor size was the most significant prognostic factor (P less than 0.0001). Cats with small tumors (1 cm3 to 8 cm3) had the best prognosis. The type of surgery, conservative vs radical, was significantly (P less than 0.01) related to disease-free interval, but was of no significance in prolonging survival time.  相似文献   
52.
Significant resistance to a second infection with Fasciola hepatica was obtained in splenectomised and sham operated rats (P less than 0.001, 78 and 76 per cent respectively) when compared with singly infected splenectomised or sham operated control groups. For both the stimulating and challenge infections, there were no significant differences in the number of flukes recovered from rats that had been splenectomised as compared to those receiving the sham operation. Thus, splenectomy did not significantly affect the ability of rats to develop an acquired immunity to F hepatica, nor were fluke recoveries from a particular schedule of infection significantly affected by the presence of absence of a spleen. It is concluded that the presence of a spleen is not necessary for the development of acquired immunity to F hepatica in the rat.  相似文献   
53.
OBJECTIVE: To evaluate the cytopathic effects of Tritrichomonas foetus and a purified cysteine protease (ie, CP30) of T foetus on cultured bovine uterine epithelial cells (BUECs) in vitro. SAMPLE POPULATION: 10 reproductive tracts were obtained from late-term bovine fetuses at a commercial abattoir. PROCEDURE: An in vitro culture system of BUECs was developed to study the cytopathic effects of T foetus and purified CP30 of T foetus on host cells. Cytotoxicity of T foetus or CP30 on exposed BUECs was determined. Fluorescence microscopy and flow cytometry analyses were used to detect apoptosis. A fluorometric assay was used to detect BUEC caspase 3 activation. The CP inhibitor E-64 and a caspase inhibitor were used to inhibit apoptosis. RESULTS: Cytopathic effects were observed in BUECs treated with parasites or CP30 and were concentration and time dependent. The BUECs underwent apoptosis in the presence of parasites or CP30. The specific CP inhibitor E-64 abolished the induction of apoptosis in BUECs by CP30. The caspase inhibitor reduced the amount of apoptosis in BUECs. CONCLUSIONS AND CLINICAL RELEVANCE: T foetus and its CP30 induce apoptosis in cultured BUECs in vitro. Induction of apoptosis by CP30 is correlated with protease activity. Endometrial cell death as a result of a T foetus infection is likely to be more important in mediating infertility than a direct effect on the conceptus. Provoking an apoptotic reaction in the host may mitigate an inflammatory reaction or immune response and therefore favor survival of the parasite in a chronic infection.  相似文献   
54.
Renal lymphoma was diagnosed, staged, and treated in 28 cats. Renal lymphoma staging was done according to clinical findings: 11 cats had stage-2 lymphomas, 5 had stage-3 lymphomas, 6 had stage-4 lymphomas, and 6 had stage-5 lymphomas. All cats were treated with chemotherapy: 17 cats had a complete response, 9 cats had a partial response, and 2 cats had no response. The cats with stage-2 lymphomas that were FeLV-test negative had the best response to treatment.  相似文献   
55.
56.
The responses of 15 cats with histologically (n=14) or cytologically (n=1) confirmed nasal squamous cell carcinoma treated with (90)Strontium plesiotherapy were reviewed retrospectively. Cats were treated such that a total dose of 50Gy was delivered at a depth of 2mm, administered in five fractions over a 10-day period. Of the cats, 11 were stage T(2), three were T(is) and one had only a cytological diagnosis precluding staging. Eleven of the cats achieved complete response (no visible lesion after 6-8 weeks) following the first cycle of therapy, and two cats with partial response achieved complete response with a second cycle of therapy. The remaining two cats achieved partial response following therapy, but further intervention was declined. Euthanasia was performed in these two cats because of progressive disease after 81 and 142 days. Of the 85% of cats that achieved a complete response, there was no recurrence of disease during a follow-up period of 134-2,043 days (median 652 days). In addition to prolonged disease-free survivals, (90)Strontium therapy produced excellent cosmetic results from the owners' perspective. These results demonstrate that superficial squamous cell carcinoma of the feline nasal planum responds excellently to (90)Strontium plesiotherapy, and this form of therapy may offer advantages over other alternatives currently available.  相似文献   
57.
58.
AIMS: To assess the sensitivity and specificity of a bulk tank milk (BTM) antibody enzyme-linked immunosorbent assay (ELISA) to detect likely infection of a dairy herd with bovine vi- ral diarrhoea virus (BVDV). The ELISA was subsequently used to estimate the prevalence of likely infected herds in parts of the North Island of New Zealand.

METHODS: BTM samples from 724 randomly selected dairy herds in the Waikato, Bay of Plenty and Northland regions of New Zealand were tested for BVDV antibodies. From this group, 20 herds were again randomly selected from each of the quartiles of the ELISA percentage inhibition (%INH) result. From each participant herd, serum from 15 randomly selected calves aged 6–18 months and 15 cows was collected and tested using an indirect blocking ELISA for BVDV antibodies.

RESULTS: Among serum results from calves from 50 herds available for analysis, 34 (68%) herds were classified as likely non-infected (0-3 seropositive among 15 calves) and 16 (32%) as likely infected (5–15 seropositive among 15 calves). Receiver- operator characteristic (ROC) analysis identified an optimal cut-off for BTM of 80%INH associated with 81% sensitivity and 91% specificity for likely herd infection. The prevalence of BVDV antibodies in cows within herds and %INH for BVDV in bulk milk were positively correlated (p<0.01). The association between bulk milk %INH and the prevalence of BVDV antibodies in calves was stronger than the same association in cows. Based on the threshold of 80%INH, the 95% confidence interval (CI) for prevalence of likely infection in the 724 herds in the Waikato, Bay of Plenty and Northland regions of New Zealand was 12–17%. Vaccination against BVDV was not significantly associated with the likely infection status of the herd based on prevalence of BVDV antibodies among calves.

CONCLUSION: An ELISA test result for BVDV antibodies in BTM ≥80%INH can be used as a threshold to indicate the presence of likely infection with BVDV in dairy herds in New Zealand, with 81% sensitivity and 91% specificity.  相似文献   
59.
60.
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