全文获取类型
收费全文 | 82272篇 |
免费 | 5112篇 |
国内免费 | 770篇 |
专业分类
林业 | 3153篇 |
农学 | 2497篇 |
基础科学 | 676篇 |
9857篇 | |
综合类 | 16461篇 |
农作物 | 3069篇 |
水产渔业 | 3764篇 |
畜牧兽医 | 42618篇 |
园艺 | 1127篇 |
植物保护 | 4932篇 |
出版年
2021年 | 720篇 |
2020年 | 798篇 |
2019年 | 985篇 |
2018年 | 1352篇 |
2017年 | 1559篇 |
2016年 | 1384篇 |
2015年 | 1327篇 |
2014年 | 1507篇 |
2013年 | 2916篇 |
2012年 | 2878篇 |
2011年 | 3465篇 |
2010年 | 2293篇 |
2009年 | 2174篇 |
2008年 | 3099篇 |
2007年 | 2958篇 |
2006年 | 2675篇 |
2005年 | 2586篇 |
2004年 | 2319篇 |
2003年 | 2362篇 |
2002年 | 2220篇 |
2001年 | 2491篇 |
2000年 | 2535篇 |
1999年 | 1945篇 |
1998年 | 795篇 |
1997年 | 706篇 |
1995年 | 749篇 |
1993年 | 667篇 |
1992年 | 1533篇 |
1991年 | 1720篇 |
1990年 | 1645篇 |
1989年 | 1595篇 |
1988年 | 1478篇 |
1987年 | 1530篇 |
1986年 | 1573篇 |
1985年 | 1399篇 |
1984年 | 1191篇 |
1983年 | 1020篇 |
1982年 | 680篇 |
1979年 | 1057篇 |
1978年 | 831篇 |
1977年 | 673篇 |
1976年 | 713篇 |
1975年 | 746篇 |
1974年 | 1004篇 |
1973年 | 984篇 |
1972年 | 955篇 |
1971年 | 880篇 |
1970年 | 852篇 |
1969年 | 805篇 |
1967年 | 704篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Kellogg VL 《Science (New York, N.Y.)》1913,38(982):601-602
142.
143.
Eidinoff ML 《Science (New York, N.Y.)》1948,108(2811):535-536
144.
145.
146.
147.
J L Marx 《Science (New York, N.Y.)》1989,245(4916):346-347
148.
L C Savon M Alonso J Rodriguez-Diego T Blandino 《Revue d'élevage et de médecine vétérinaire des pays tropicaux》1992,45(1):30-31
The attenuation of a Babesia bovis strain depends on its protease content. The present work evaluates this parameter on a virulent strain, before and after attenuation by quick passages on splenectomized calves. The protease activity at different pH values was determined in protein fractions from the blood of calves. The enzymatic test showed marked differences between the protease content of both substrains. 相似文献
149.
DARIEN LAWRENCE BSc BVSC JAMIE R. BELLAH DVM Dipiomate ACVS D. J. MEYER DVM Dipiomate ACVIM Dipiomate ACVP L. ROTH DVM PhD Dipiomate ACVP 《Veterinary surgery : VS》1992,21(6):446-451
The use of a cholecystostomy catheter for temporary bile diversion was investigated in four cats with experimentally induced extrahepatic bile duct obstruction. Eighteen days after ligation of the common bile duct, a 6.5 F accordion catheter was placed in the gallbladder with a 22 g Hawkins needle-guide system through a paracostal incision. Biochemical parameters and fasting serum bile acids were monitored for 16 days. There were significant decreases in mean total bilirubin, aspartate aminotransferase, and fasting serum bile acids within 72 hours of bile diversion, and in mean alanine aminotransferase within 96 hours. Attitude and appetite improved, and the catheter was tolerated well. Positive bile cultures developed in three cats. Histologic changes in the gallbladder included mucosal ulcerations, a mixed inflammatory cellular infiltration, and fibrosis of the submucosa. 相似文献
150.
One hundred two fecal specimens from psittacine birds submitted to Veterinary Laboratory Services of the California Department of Food and Agriculture at Petaluma were screened for Chlamydia psittaci by a direct immunofluorescence assay using a fluorescein-labeled monoclonal antibody conjugate specific for Chlamydia sp. Results were compared with those obtained by isolation of chlamydia in cultures of McCoy mouse cells. The relative specificity of the direct fluorescent antibody test on fecal smears was 98.9% and the relative sensitivity was 62.5%. The results of this study suggested that the direct fluorescent antibody test was highly specific, and it proved to be a useful same-day antemortem diagnostic test for birds with symptomatic chlamydial infection. The use of centrifugation in the cell culture assay was found to significantly enhance the level of chlamydial infection in cell culture. 相似文献