全文获取类型
收费全文 | 129586篇 |
免费 | 7236篇 |
国内免费 | 87篇 |
专业分类
林业 | 4902篇 |
农学 | 3779篇 |
基础科学 | 803篇 |
14480篇 | |
综合类 | 23011篇 |
农作物 | 4670篇 |
水产渔业 | 6118篇 |
畜牧兽医 | 69646篇 |
园艺 | 1490篇 |
植物保护 | 8010篇 |
出版年
2018年 | 1697篇 |
2017年 | 1873篇 |
2016年 | 1686篇 |
2015年 | 1518篇 |
2014年 | 1808篇 |
2013年 | 4966篇 |
2012年 | 3406篇 |
2011年 | 4213篇 |
2010年 | 2617篇 |
2009年 | 2709篇 |
2008年 | 4004篇 |
2007年 | 3823篇 |
2006年 | 3700篇 |
2005年 | 3321篇 |
2004年 | 3203篇 |
2003年 | 3274篇 |
2002年 | 3099篇 |
2001年 | 3989篇 |
2000年 | 4025篇 |
1999年 | 3185篇 |
1998年 | 1306篇 |
1997年 | 1304篇 |
1996年 | 1232篇 |
1995年 | 1501篇 |
1994年 | 1356篇 |
1993年 | 1296篇 |
1992年 | 2800篇 |
1991年 | 3071篇 |
1990年 | 2879篇 |
1989年 | 2893篇 |
1988年 | 2712篇 |
1987年 | 2772篇 |
1986年 | 2826篇 |
1985年 | 2772篇 |
1984年 | 2196篇 |
1983年 | 1974篇 |
1982年 | 1316篇 |
1979年 | 2081篇 |
1978年 | 1690篇 |
1977年 | 1515篇 |
1976年 | 1461篇 |
1975年 | 1511篇 |
1974年 | 1896篇 |
1973年 | 1912篇 |
1972年 | 1850篇 |
1971年 | 1671篇 |
1970年 | 1682篇 |
1969年 | 1521篇 |
1968年 | 1344篇 |
1967年 | 1389篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A. A. Roess A. M. McCollum K. Gruszynski H. Zhao W. Davidson N. Lafon T. Engelmeyer B. Moyer C. Godfrey H. Kilpatrick A. Labonte J. Murphy D. S. Carroll Y. Li I. K. Damon 《Zoonoses and public health》2013,60(8):543-548
In 2008, two deer hunters in Virginia and Connecticut were infected with a unique strain of pseudocowpox virus, a parapoxvirus. To estimate the prevalence of this virus, and in an attempt to define the reservoir, Parapoxvirus surveillance was undertaken between November 2009 and January 2010. 125 samples from four ruminant species (cows, goat, sheep and white‐tailed deer) were collected in Virginia, and nine samples from white‐tailed deer were collected in Connecticut. We found no evidence that the parapoxvirus species that infected the deer hunters is circulating among domesticated ruminants or white‐tailed deer. However, parapoxvirus DNA of a different parapoxvirus species, bovine papular stomatitis virus (BPSV), was detected in 31 samples obtained from asymptomatic cattle in Virginia. Parapoxvirus DNA–positive cattle originated from the same counties indicating probable transmission among animals. Molecular analysis identified BPSV as the parapoxvirus affecting animals. Asymptomatic parapoxvirus infections in livestock, particularly young animals, may be common, and further investigation will inform our knowledge of virus transmission. 相似文献
992.
C. Drake B.Sc. A.B. Grant B.Sc. Ph.D. W.J. Hartley M.R.C.V.S. 《New Zealand veterinary journal》2013,61(1):4-5
Extract At the Annual General Meeting of the New Zealand Veterinary Association in 1951 a motion was carried “that this meeting recommend that a journal be started, and ask Council to investigate the matter from all aspects, and to report to the next Annual General Meeting.” To implement the wishes of the meeting, Council appointed a subcommittee which reported to the Annual General Meeting of 1952. The report, after dealing with costs and publishable material, recommended as follows:— 相似文献
993.
994.
995.
996.
R.M.P. Rocha L.F. Lima A.M.C.V. Alves J.J.H. Celestino M.H.T. Matos I.B. Lima-Verde M.P. Bernuci C.A.P. Lopes S.N. Báo C.C. Campello A.P.R. Rodrigues J.R. Figueiredo 《Domestic animal endocrinology》2013
The aim of this study was to investigate the effects of melatonin and follicle-stimulating hormone (FSH) on the in vitro culture of goat preantral follicles. Ovarian fragments were cultured for 7 d in α-minimum essential medium (α-MEM+) containing melatonin (100, 250, 500, or 1,000 pM), FSH (50 ng/mL), or a combination of the 2 hormones and further analyzed by histology and transmission electron and fluorescent microscopy. The results showed that after 7 d of culture, tissues cultured in α-MEM+ alone or supplemented with FSH alone, melatonin (500 and 1,000 pM), or the combination of FSH and melatonin (1,000 pM) maintained percentages of normal preantral follicles similar to the fresh control. In contrast to the noncultured tissues, the percentage of developing follicles was increased under all culture conditions after 7 d (P < 0.05). The addition of 1,000 pM melatonin associated with FSH to the culture medium increased follicular and oocyte diameters compared with α-MEM+ alone after 7 d of culture (P < 0.05). Ultrastructural and fluorescent analyses confirmed the integrity of follicles cultured with 1,000 pM of melatonin plus FSH for 7 d. In conclusion, this study demonstrated that the interaction between melatonin and FSH maintains ultrastructural integrity and stimulates further growth of cultured caprine preantral follicles. 相似文献
997.
F. YANG N. SUN Y. X. SUN Q. SHAN H. Y. ZHAO D. P. ZENG Z. L. ZENG 《Journal of veterinary pharmacology and therapeutics》2013,36(2):192-200
Yang, F., Sun, N., Sun, Y. X., Shan, Q., Zhao, H. Y., Zeng, D. P., Zeng, Z. L. A physiologically based pharmacokinetics model for florfenicol in crucian carp and oral‐to‐intramuscular extrapolation. J. vet. Pharmacol. Therap. 36 , 192–200. In this study, an oral physiologically based pharmacokinetics (PBPK) model was developed for florfenicol in crucian carp (Carassius auratus). Subsequently, oral‐to‐intramuscular extrapolation was performed and the two models were used to predict florfenicol concentrations in the edible tissues of crucian carp. The oral model gave good predictions in most tissues, except for kidney and liver in which the florfenicol concentrations were underestimated at the later time points. In contrast, using the intramuscular model, the concentrations in the kidney were overestimated at the later time points. Both models had the best predictive ability in the main edible tissue, the muscle. The oral model also accurately predicted the florfenicol concentrations in the muscle after multiple doses. The present study demonstrated the feasibility of predicting florfenicol concentrations in the edible tissues of crucian carp using a route‐to‐route extrapolation method. 相似文献
998.
999.
H.S. Cameron D.V.M. Ph.D. 《New Zealand veterinary journal》2013,61(3):41-44
Extract First let me express my appreciation of being the recipient of a Fulbright Fellowship for research in New Zealand and also for the privilege of discussing brucellosis before the New Zealand Veterinary Association. 相似文献
1000.
T.J. McClure B.V.Sc. 《New Zealand veterinary journal》2013,61(5):107-112
Abstract Extract Sir.—I refer to the paper by Day(1) on induction of parturition in a dairy herd. This report was read with a considerable degree of interest as it included results which are significantly different from those which we would have expected from extensive field experience in New Zealand and overseas. 相似文献