全文获取类型
收费全文 | 115001篇 |
免费 | 5982篇 |
国内免费 | 76篇 |
专业分类
林业 | 5049篇 |
农学 | 3658篇 |
基础科学 | 588篇 |
12778篇 | |
综合类 | 21708篇 |
农作物 | 4263篇 |
水产渔业 | 5603篇 |
畜牧兽医 | 59120篇 |
园艺 | 1391篇 |
植物保护 | 6901篇 |
出版年
2018年 | 1462篇 |
2017年 | 1567篇 |
2016年 | 1485篇 |
2015年 | 1257篇 |
2014年 | 1539篇 |
2013年 | 4048篇 |
2012年 | 2721篇 |
2011年 | 3426篇 |
2010年 | 2286篇 |
2009年 | 2171篇 |
2008年 | 3363篇 |
2007年 | 3318篇 |
2006年 | 3067篇 |
2005年 | 2925篇 |
2004年 | 2850篇 |
2003年 | 2858篇 |
2002年 | 2649篇 |
2001年 | 3640篇 |
2000年 | 3662篇 |
1999年 | 2954篇 |
1998年 | 1156篇 |
1997年 | 1119篇 |
1995年 | 1316篇 |
1994年 | 1080篇 |
1993年 | 1068篇 |
1992年 | 2380篇 |
1991年 | 2529篇 |
1990年 | 2589篇 |
1989年 | 2492篇 |
1988年 | 2339篇 |
1987年 | 2358篇 |
1986年 | 2366篇 |
1985年 | 2281篇 |
1984年 | 1869篇 |
1983年 | 1672篇 |
1982年 | 1084篇 |
1979年 | 1730篇 |
1978年 | 1372篇 |
1977年 | 1197篇 |
1976年 | 1128篇 |
1975年 | 1270篇 |
1974年 | 1619篇 |
1973年 | 1635篇 |
1972年 | 1678篇 |
1971年 | 1547篇 |
1970年 | 1439篇 |
1969年 | 1379篇 |
1968年 | 1157篇 |
1967年 | 1221篇 |
1966年 | 1097篇 |
排序方式: 共有10000条查询结果,搜索用时 119 毫秒
291.
Duration of maternal immunity to peste des petits ruminants 总被引:1,自引:0,他引:1
292.
Chronic osteomyelitis and septic arthritis involving the 3rd and 4th metatarsophalangeal joints were diagnosed in a Doberman Pinscher. Arthrodesis of the 3rd and 4th metatarsophalangeal joints resulted in a subtle persistent gait abnormality, but limb function was preserved. Arthrodesis of metatarsophalangeal joints is an alternative to amputation, especially when main weight-bearing digits are involved. 相似文献
293.
294.
T R Thedford L W Johnson 《Veterinary Clinics of North America: Food Animal Practice》1989,5(1):145-157
Although there are notable infectious conditions that are capable of producing clinical disease in the NWC, overall, these species are quite healthy. Of the bacterial diseases, enterotoxemia caused by Clostridium perfringens types C and D would be deemed the most significant in North America, while type A also would be regarded as important in South America. Other important bacterial infections of potential concern are tuberculosis, Johne's disease, anthrax, malignant edema, actinomycosis, tetanus, and the South American condition referred to as alpaca fever, which, to date, has not been observed in North America. Fungal infections include classical ringworm, principally caused by Trichophyton spp., and the cases of coccidioidomycosis that are associated with the arid desert lands of the southwestern United States. Most notable of naturally occurring viral infections in the NWC would be rabies, ecthyma, and a recently described blindness neuropathy that has been associated with the equine herpesvirus I. NWC can be infected experimentally with agents causing hoof-and-mouth disease and vesicular stomatitis, but naturally occurring cases do not seem to occur. Serological evidence of exposure to many viral agents, including blue tongue, parainfluenza 3, bovine respiratory syncytial virus, bovine herpesvirus I, bovine viral diarrhea, influenza A, and rotavirus, has been demonstrated; however, no clinical disease associated with these agents, as yet, is apparent. 相似文献
295.
K Fehlhaber G Krüger V Schubert H Rolletschek 《Archiv fuer experimentelle veterinaermedizin》1989,43(6):855-862
Reference is made to work undertaken by Stehle (1983) on rapid semiquantitative determination of urinary protein in pigs for slaughter to identify premortal strain and stress, with additional studies being conducted into the suitability of the method. The investigations performed for this study covered urinary protein samples from 59 living and 762 slaughtered pigs. The Biophan E paper strip test was applied to groups of animals, and, when compared to high-accuracy laboratory determination of urinary protein, it provided sufficiently accurate information on the presence of stress-related proteinuria. Its accuracy, however, proved to be insufficient, when individual animals were examined. The number of clearly stressed slaughter pigs was unexpectedly high, although the same animals had been rated clinically inconspicuous prior to slaughter. Brief rest period resulted in significant rise of stress. The Biophan E paper strip test was found to be suitable for instantaneous determination of stress and strain on pigs for slaughter. 相似文献
296.
Isolation of Haemophilus somnus from bovine milk 总被引:1,自引:0,他引:1
297.
W Ahne J R Winton T Kimura 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1989,36(8):561-567
Infectious diseases remain one of the most important limitations to the successful propagation of aquatic animals. Most of the losses caused by pathogens in aquaculture could be prevented by health inspection, adequate environment and sound management practices. Effective control measures, mainly based upon 1) avoidance of pathogens 2) modification of the environment 3) improvement of host resistance 4) vaccination and 5) chemoprophylaxis are described. 相似文献
298.
Monorchidism in the horse 总被引:1,自引:0,他引:1
Six horses with monorchidism, identified at surgery for cryptorchidectomy, are reported. All six presented with a single scrotal testis. Following surgical removal of one testis, they were either hormonally, anatomically or behaviourally determined to be geldings. Three other horses reported in the literature are reviewed. Of these nine cases of monorchidism, eight were thought to be caused by testicular degeneration and one by testicular agenesis. The vaginal process was present in all of the former and absent in the latter. The left side was involved in five of these eight horses. In seven, the epididymis was absent and, in the remaining two, only the epididymal tail was present. The condition was thought to be congenital in the six horses in this series. A surgical approach to identify accurately monorchid horses is described. 相似文献
299.
The effect of intravenous doses of cortisol and xylazine on the quantity of copper excreted in response to 100 and 200 mg doses of tetrathiomolybdate (TTM) was studied in seven sheep. Cortisol alone produced a non-significant 1.4-fold increase and had no enhancing action on the response to TTM. Xylazine produced a significant 2.25-fold increase, doubled the quantity of copper excreted in response to both doses of TTM and reduced bile flow by approximately 35 per cent. The alpha 2 antagonist, idazoxan, prevented both the latter effects showing that they were due to xylazine's alpha 2-agonistic action. It is suggested that the combination of an alpha 2-agonist with the intravenous injection of TTM in the treatment of acute copper toxicity in sheep could reduced by 50 per cent the amount of molybdenum needed. 相似文献
300.
H Adam G von Lengerken D Olthoff M Schwalbe M Wicke 《Archiv fuer experimentelle veterinaermedizin》1989,43(2):293-299
Membraneous phospholipids of subcellular structures were determined from the musculature of German Landrace pigs of the GDR, following exposure to halothane. Mating variants A (H+ male X H+ female), B (H+ male X H- female), and C (H- male X H+ female) were used for positive responders (MHS), while variants B, C, and D (H- male X H- female) were used for negative responders (MHN). Four phospholipid fractions were recorded from the muscle samples for mitochondria and microsomes (according to SR section). Differences between the MHS and MHN groups for the above fractions and without consideration of mating variants and genotype were not observed, although unambiguous responses were exhibited by all animals, either positive or negative to halothan. Significant differences with regard to the above phospholipid fractions were recordable only for variant A (MHS group) as compared to D (MHN), in other words, for the homozygous genotypes, once the above results had been rearranged within MHS and MHN along with different mating variants and genotypes. However, no unambiguous results were obtainable for the heterozygous genotypes of mating variants B and C. Possible underlying reasons are discussed in some detail. The results obtained from mating variants A and D are likely to confirm earlier findings and seem to suggest that the sarcoplasmic reticulum is the primary site of origin of susceptibility to halothane or malignant hyperthermia. 相似文献