全文获取类型
收费全文 | 82003篇 |
免费 | 4309篇 |
国内免费 | 52篇 |
专业分类
林业 | 3677篇 |
农学 | 2372篇 |
基础科学 | 392篇 |
8102篇 | |
综合类 | 15622篇 |
农作物 | 3116篇 |
水产渔业 | 3463篇 |
畜牧兽医 | 44059篇 |
园艺 | 934篇 |
植物保护 | 4627篇 |
出版年
2018年 | 995篇 |
2017年 | 1081篇 |
2016年 | 968篇 |
2015年 | 940篇 |
2014年 | 1199篇 |
2013年 | 2889篇 |
2012年 | 1909篇 |
2011年 | 2363篇 |
2010年 | 1557篇 |
2009年 | 1542篇 |
2008年 | 2259篇 |
2007年 | 2238篇 |
2006年 | 2019篇 |
2005年 | 1958篇 |
2004年 | 1944篇 |
2003年 | 1968篇 |
2002年 | 1905篇 |
2001年 | 2369篇 |
2000年 | 2346篇 |
1999年 | 1964篇 |
1998年 | 869篇 |
1997年 | 863篇 |
1995年 | 963篇 |
1994年 | 781篇 |
1993年 | 833篇 |
1992年 | 1646篇 |
1991年 | 1693篇 |
1990年 | 1838篇 |
1989年 | 1761篇 |
1988年 | 1634篇 |
1987年 | 1598篇 |
1986年 | 1579篇 |
1985年 | 1593篇 |
1984年 | 1319篇 |
1983年 | 1218篇 |
1982年 | 804篇 |
1979年 | 1250篇 |
1978年 | 981篇 |
1977年 | 855篇 |
1976年 | 803篇 |
1975年 | 917篇 |
1974年 | 1202篇 |
1973年 | 1242篇 |
1972年 | 1255篇 |
1971年 | 1183篇 |
1970年 | 1103篇 |
1969年 | 1004篇 |
1968年 | 863篇 |
1967年 | 906篇 |
1966年 | 838篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
202.
G H Wentink S van Dijk S A Goedegebuure J Vos T Wensing 《The Veterinary quarterly》1992,14(4):159-160
A syndrome very similar to hepatic lipidosis is described in dairy cows during the dry period. After being sent to pasture the animals did not eat well for undetermined reasons. The disease phenomena were mainly observed in animals carrying twins. At post mortem examination severe falty infiltration was found in the 3 animals made available for post mortem examination. Increase of the energy supply to the dry cows by addition of maize silage to the ration prevented new cases. 相似文献
203.
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
204.
The severity of charcoal root disease of conifer seedlings (Abies concolor, A. magnified, Pinus jeffreyi, P. lambertiana, and Pseudotsuga menziesii) was a power function of the sclerotial density of the fungus (Macrophomina phaseolina) in nursery soil. 相似文献
205.
Ariana M.P. Nap Yvonne W.E.A. Pollak Walter E. van den Brom Ad Rijnberk DVM PhD 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1994,8(4):302-303
Thyroidal 99m TcO4 (pertechnetate) uptake percentages were determined in unanesthetized euthyroid (n = 13) and hyperthyroid (n = 18) cats. Maximal uptakes were observed 60 minutes after IV injection of the radionuclide and ranged from 0.3 to 3.9% of the dose in euthyroid cats (median 2.23%) and from 5.2% to 23.9% of the dose in hyperthyroid cats (median 14.8%) ( P < .05). There were no overlaps in pertechnetate uptake percentages during any of the intervals evaluated. It is concluded that the optimal time for visualization of the thyroid by 99m TcO4 -scanning is 60 minutes after IV injection of the radionuclide. Calculation of the percentage uptake is of additional diagnostic value. 相似文献
206.
207.
M Kachani R A Oliver C G Brown H Ouhelli R L Spooner 《Veterinary immunology and immunopathology》1992,34(3-4):221-234
Western blot analysis of Theileria annulata antigens was carried out using sera collected from cattle which had been immunised and challenged with either T. annulata sporozoites or schizont-infected cells. Three antigens between 71 and 73 kDa proved to be common to the three stages of parasite studied: sporozoites, schizonts and piroplasms. An antigen was found at 32 kDa which was specific to T. annulata piroplasms. Results were reproducible using sera from Morocco and the UK. At least one of the proteins at 71-73 kDa, but not that at 32 kDa were also recognised by sera from animals infected with Babesia species. 相似文献
208.
Destruction of Trichinella spiralis spiralis during the preparation of the "dry cured" pork products proscuitto, proscuittini and Genoa salami 总被引:1,自引:1,他引:0 下载免费PDF全文
Genoa salami, proscuittini and proscuitto were prepared from pork carcasses that were heavily infected experimentally with Trichinella spiralis spiralis. Genoa salami was prepared with salt concentrations of 2.0%, 2.75% and 3.3%. Proscuitto was prepared by two procedures approved by Agriculture Canada. At various times postpreparation, samples of the various cured products were taken and examined by pepsin digestion and rat bioassay for the presence of viable trichinae. Water activity and pH of the cured meat were also determined. Curing of the various products was shown to destroy the Trichinella larvae. Pepsin digestion revealed that larvae progressively became loosely coiled, uncoiled and more subject to digestion (ghost larvae) during the curing process. Rat bioassay revealed the presence of viable trichinae in the proscuitto prepared using a sodium chloride salt mixture at day 34 but not at day 48 postpreparation. All other bioassays carried out on Genoa salami between 13 and 42 days postpreparation, on proscuittini between days 27 and 69 and on proscuitto between days 34 and 69 were negative for viable trichinae. Under the conditions of this study, preparing Genoa salami with salt concentrations as low as 2% did not appear to affect the destruction of Trichinella larvae. 相似文献
209.
M Washizu K Kobayashi K Misaka T Hayashi G Kinoshita M Kondo S Aoki H Orima T Washizu 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1992,54(5):1051-1053
A 2-year-old female Japanese domestic cat weighing 3.6 kg was presented due to marked abdominal distention and was diagnosed as hepatic cyst. The bile acid concentration of the hepatic cyst was as low as the serum bile acid concentration. The membrane of the cysts was excised from the edge of the compressed hepatic tissue and no other surgical manipulation was performed. This surgical procedure is simple and quick compared to hepatic lobectomy, however, it is necessary to evaluate the fluid of the cyst before performing this procedure. 相似文献
210.
Michael R. Metcalf DVM MS Lloyd P. Tate DVM Loouis C. Sellett MS 《Veterinary radiology & ultrasound》1989,30(2):80-87