全文获取类型
收费全文 | 889篇 |
免费 | 53篇 |
国内免费 | 3篇 |
专业分类
林业 | 120篇 |
农学 | 15篇 |
基础科学 | 3篇 |
106篇 | |
综合类 | 172篇 |
农作物 | 18篇 |
水产渔业 | 68篇 |
畜牧兽医 | 402篇 |
园艺 | 21篇 |
植物保护 | 20篇 |
出版年
2023年 | 10篇 |
2022年 | 9篇 |
2021年 | 19篇 |
2020年 | 20篇 |
2019年 | 24篇 |
2018年 | 26篇 |
2017年 | 23篇 |
2016年 | 11篇 |
2015年 | 25篇 |
2014年 | 16篇 |
2013年 | 43篇 |
2012年 | 57篇 |
2011年 | 63篇 |
2010年 | 31篇 |
2009年 | 25篇 |
2008年 | 39篇 |
2007年 | 32篇 |
2006年 | 40篇 |
2005年 | 32篇 |
2004年 | 27篇 |
2003年 | 35篇 |
2002年 | 24篇 |
2001年 | 18篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1993年 | 6篇 |
1992年 | 18篇 |
1991年 | 15篇 |
1990年 | 14篇 |
1989年 | 11篇 |
1988年 | 15篇 |
1987年 | 12篇 |
1986年 | 14篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1976年 | 5篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1972年 | 6篇 |
1916年 | 4篇 |
1871年 | 4篇 |
1869年 | 6篇 |
1868年 | 7篇 |
1867年 | 9篇 |
1866年 | 5篇 |
1864年 | 4篇 |
1863年 | 8篇 |
1859年 | 4篇 |
排序方式: 共有945条查询结果,搜索用时 65 毫秒
1.
Catherine Bradley Suresh Andrew Sethi Joshua Ashline Jonathon Gerken 《Ecology of Freshwater Fish》2017,26(4):695-706
In this study, we examined summer and fall freshwater rearing habitat use by juvenile coho salmon (Oncorhynchus kisutch) in the quickly urbanising Big Lake drainage in south‐central Alaska. Habitat use was assessed by regressing fish count data against habitat survey information across thirty study sites using generalised linear mixed models. Habitat associations were examined by age‐0 and age‐1+ cohorts separately, providing an opportunity to compare habitat use across different juvenile coho salmon life stages during freshwater rearing. Regression results indicated that the age‐0 cohorts were strongly associated with shallow, wide stream reaches with in‐stream vegetation, whereas age‐1+ cohorts were associated with deeper stream reaches. Furthermore, associations between fork length and habitat characteristics suggest cohort‐specific habitat use patterns are distinct from those attributable to fish size. Habitat use information generated from this study is being used to guide optimal fish passage restoration planning in the Big Lake drainage. Evidence for habitat use partitioning by age cohort during freshwater juvenile rearing indicates that pooling age cohorts into a single “juvenile” stage for the purposes of watershed management may mask important habitat use dynamics. 相似文献
2.
3.
J L?fstedt J A Roth R F Ross W C Wagner 《American journal of veterinary research》1983,44(7):1224-1228
In a study of susceptibilities of sows from 2 herds to experimentally induced Escherichia coli mastitis, a marked difference was seen. The "susceptible" sows were from a conventional herd and "resistant" sows were from a specific-pathogen-free herd. The purpose of the study was to determine whether deficient neutrophil function was associated with increased susceptibility to E coli-induced mastitis. Four in vitro procedures were used to evaluate polymorphonuclear leukocyte (PMN) function: (i) random migration under agarose, (ii) ingestion of 125I-iododeoxyuridine-labeled Staphylococcus aureus, (iii) quantitative nitroblue tetrazolium reduction, and (iv) iodination. After parturition and intramammary inoculation with E coli, sows from the susceptible herd were neutropenic and the neutrophils which were present in the peripheral blood had reduced function. Specifically, there were depressed random migration under agarose, S aureus ingestion, and iodination when compared with PMN function in resistant sows. These data indicate that susceptibility to E coli mastitis was associated with deficiencies in PMN numbers and function. Potential causes of the neutrophil dysfunction are discussed and include possible systemic hormonal aberrations or the presence of an inapparent viral or bacterial infection. 相似文献
4.
5.
J O Joshua 《The Veterinary record》1975,96(14):300-302
An eruptive condition seen on certain mucous membranes of dogs occurs frequently but often asymptomatically. Lesions have been found to be present in over 60 percent of male dogs. The infection is probably due to a canine herpes virus and has been termed conveniently but inaccurately "dog pox". In many cases lesions are present without observable clinical signs but severe irritation, especially related to lesions in the lower bowel, can give rise to marked symptoms which may be confused with abnormality of the para-anal sacs, or to chronic diarrhoea of a type suggestive of colitis. The incidence, sites of infection and possible syndromes which may be ascribed to the condition are briefly discussed on a clinical basis only. 相似文献
6.
The ability to predict species occurrences quickly is often crucial for managers and conservation biologists with limited
time and funds. We used measured associations with landscape patterns to build accurate predictive habitat models that were
quickly and easily applied (i.e., required no additional data collection in the field to make predictions). We used classification
trees (a nonparametric alternative to discriminant function analysis, logistic regression, and other generalized linear models)
to model nesting habitat of red-naped sapsuckers (Sphyrapicus nuchalis), northern flickers (Colaptes auratus),tree swallows (Tachycineta bicolor), and mountain chickadees (Parus gambeli) in the Uinta Mountains of northeastern Utah, USA. We then tested the predictive capability of the models with independent
data collected in the field the following year. The models built for the northern flicker, red-naped sapsucker, and tree swallow
were relatively accurate (84%, 80%, and 75% nests correctly classified,respectively)compared to the models for the mountain
chickadee (50% nests correctly classified). All four models were more selective than a null model that predicted habitat based
solely on a gross association with aspen forests. We conclude that associations with landscape patterns can be used to build
relatively accurate, easy to use, predictive models for some species. Our results stress, however, that both selecting the
proper scale at which to assess landscape associations and empirically testing the models derived from those associations
are crucial for building useful predictive models.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Abdilatif Mohamed Haji Onono Joshua Orungo Mutua Florence Kanini 《Tropical animal health and production》2018,50(7):1701-1710
Tropical Animal Health and Production - Small ruminants’ production contributes to livelihood of pastoral communities, but this faces myriad constraints. This study aimed at identifying... 相似文献
8.
Josephine A. Dornbusch Laura E. Selmic Pin‐Chieh Huang Jonathan P. Samuelson Eric M. McLaughlin Vincent A. Wavreille Jessica A. Ogden Brittany Abrams Alex Kalamaras Eric Green Eric T. Hostnik Lincoln Every Jason A. Fuerst Ryan Jennings Christopher Premanandan Joshua N. Lorbach Sarah C. Linn Aneesh Alex Janet E. Sorrells Lingxiao Yang Stephen A. Boppart 《Veterinary surgery : VS》2021,50(1):111-120
9.