全文获取类型
收费全文 | 185535篇 |
免费 | 10238篇 |
国内免费 | 299篇 |
专业分类
林业 | 8113篇 |
农学 | 6535篇 |
基础科学 | 1254篇 |
23924篇 | |
综合类 | 27945篇 |
农作物 | 7131篇 |
水产渔业 | 9659篇 |
畜牧兽医 | 96543篇 |
园艺 | 2523篇 |
植物保护 | 12445篇 |
出版年
2019年 | 1822篇 |
2018年 | 2848篇 |
2017年 | 3172篇 |
2016年 | 2972篇 |
2015年 | 2543篇 |
2014年 | 3182篇 |
2013年 | 7605篇 |
2012年 | 5666篇 |
2011年 | 6776篇 |
2010年 | 4675篇 |
2009年 | 4743篇 |
2008年 | 6835篇 |
2007年 | 6487篇 |
2006年 | 6149篇 |
2005年 | 5617篇 |
2004年 | 5590篇 |
2003年 | 5667篇 |
2002年 | 5352篇 |
2001年 | 6338篇 |
2000年 | 6124篇 |
1999年 | 5012篇 |
1998年 | 2085篇 |
1997年 | 2042篇 |
1996年 | 1861篇 |
1995年 | 2196篇 |
1994年 | 1917篇 |
1993年 | 1881篇 |
1992年 | 3802篇 |
1991年 | 3972篇 |
1990年 | 4001篇 |
1989年 | 3913篇 |
1988年 | 3589篇 |
1987年 | 3547篇 |
1986年 | 3487篇 |
1985年 | 3342篇 |
1984年 | 2768篇 |
1983年 | 2477篇 |
1982年 | 1634篇 |
1979年 | 2412篇 |
1978年 | 1909篇 |
1977年 | 1687篇 |
1976年 | 1589篇 |
1975年 | 1741篇 |
1974年 | 1979篇 |
1973年 | 2076篇 |
1972年 | 1997篇 |
1971年 | 1797篇 |
1970年 | 1786篇 |
1969年 | 1748篇 |
1967年 | 1513篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
952.
Estrogen and progesterone receptor status of mammary carcinomas and correlation with clinical outcome in dogs. 总被引:3,自引:0,他引:3
E A Sartin S Barnes R P Kwapien L G Wolfe 《American journal of veterinary research》1992,53(11):2196-2200
Estrogen and progesterone receptors (ER, PR) were measured in cytosol fractions from 18 primary canine mammary carcinomas by use of biochemical assays. One or both receptors were detected (> 10 fmol/mg of cytosol protein) in 11 tumors: 5 ER and PR; 2 ER only; 4 PR only. Mean cytoplasmic receptor concentrations (fmol/mg of cytosol protein) were 22.8 +/- 2.9 (SEM) for ER and 51.0 +/- 10.3 for PR in tumors containing ER and PR, 28.8 +/- 12.1 for ER in tumors containing only ER and 13.2 +/- 1.5 for PR in tumors containing only PR. Estrogen or progesterone receptors or both were identified in 6 of 9 tubular adenocarcinomas, 4 of 5 papillary adenocarcinomas, and 1 of 1 squamous cell carcinoma. These receptors were not identified in solid carcinomas (n = 2) or a single spindle cell carcinoma. Although the number of cases was limited, survival times of dogs tended to be longest in those with tumors containing ER alone or in combination with PR, intermediate in those with tumors containing only PR, and shortest in those with tumors without ER or PR. A correlation was not apparent between receptor status and age, presence of ovaries, tumor size, or histologic classification of the tumor. In the analysis of this series, the extent of surgery (mastectomy of the involved gland vs unilateral or bilateral mastectomy) did not appear to influence the outcome of the disease, and metastasis to regional lymph nodes did not appear to be a reliable prognostic indicator. 相似文献
953.
Tablets containing praziquantel, pyrantel embonate, and febantel were tested for efficacy against helminths in dogs. A single treatment with this drug combination gave 100% reductions in Toxocara canis and Taenia hydatigena in experimentally induced infections in dogs. In dogs with naturally acquired infections, treatment gave > 97 to 98% reductions in fecal egg counts attributable to Toxascaris leonina, T canis, and Uncinaria stenocephala. Efficacy against Trichuris vulpis was > 92%. 相似文献
954.
Aerobic bacterial populations were studied on the distal hair coat and at the skin surface of the shoulder, rump and abdomen of 10 healthy dogs. Coagulase negative staphylococci (CNS) were more frequently isolated from the hair than the skin at the shoulder and rump. There was no difference in the isolation rate of coagulase positive staphylococci (CPS) (Staphylococcus intermedius) between the hair and skin. Total skin counts were greatest on the abdomen whereas CNS counts from the hair were least at this site. There were no differences between CPS counts at the three sites on either hair or skin. The populations on the relatively unfavourable microenvironment of the distal hair may represent contamination rather than colonisation. The low populations of CPS at the skin surface also indicate contamination or transient colonisation rather than true resident status. 相似文献
955.
Pestivirus is a common contaminant in maedi-visna and caprine arthritis-encephalitis virus stocks. 下载免费PDF全文
Eight different laboratory stocks of maedi-visna or caprine arthritis-encephalitis virus were examined for the presence of pestiviruses by a fixed-cell immunoperoxidase assay with polyclonal and monoclonal antibodies. All of the viral stocks examined were found to contain noncytopathic pestivirus contaminants. The panel of monoclonal antibodies could not type the isolates as being more related to bovine virus diarrhea virus or border disease virus. However, the results did indicate that all isolates were not the same, except for two from the same laboratory where the source of pestivirus contamination may have been common. 相似文献
956.
J.A Stegeman M.C.M De Jong H.M.J.F Van Der Heijden A.R.W Elbers T.G Kimman 《Research in veterinary science》1996,61(3):263-267
The performance of tests for the detection of antibodies to Aujeszky's disease virus glycoprotein E (ge) in a target population was evaluated by constructing and analysing receiver operating characteristic (roc) curves. These curves assess the discriminating ability of a test over the entire range of test signals. The advantages of applying the analysis to a sample of the target population (all commercial pigs in the Netherlands), as compared to using a panel of test sera, are that the estimates of sensitivity and specificity, the comparisons between tests and the choices of the cut-off values are all relevant for the target population. The results of a gE-elisa in colostrum (test A) and in a single droplet of whole blood (test B) were compared with the results obtained with the same elisa in serum (gold standard). The area under the ROC curve, which is a quantitative measure of test performance, was significantly (P<0·01) smaller with test A than test B or the gold standard, indicating that test B performed better than test A. No significant difference was observed between test B and the gold standard. 相似文献
957.
Silverstein RM 《Science (New York, N.Y.)》1981,213(4514):1326-1332
Pesticides have not been a satisfactory solution to the control of insect pests. Pheromones show promise as a component of integrated pest management. 相似文献
958.
959.
960.