全文获取类型
收费全文 | 80018篇 |
免费 | 4293篇 |
国内免费 | 97篇 |
专业分类
林业 | 3299篇 |
农学 | 2071篇 |
基础科学 | 461篇 |
8709篇 | |
综合类 | 15452篇 |
农作物 | 3166篇 |
水产渔业 | 3598篇 |
畜牧兽医 | 42280篇 |
园艺 | 854篇 |
植物保护 | 4518篇 |
出版年
2019年 | 745篇 |
2018年 | 1119篇 |
2017年 | 1236篇 |
2016年 | 1086篇 |
2015年 | 930篇 |
2014年 | 1227篇 |
2013年 | 2688篇 |
2012年 | 2166篇 |
2011年 | 2637篇 |
2010年 | 1649篇 |
2009年 | 1765篇 |
2008年 | 2658篇 |
2007年 | 2465篇 |
2006年 | 2343篇 |
2005年 | 2186篇 |
2004年 | 2129篇 |
2003年 | 2193篇 |
2002年 | 1966篇 |
2001年 | 2446篇 |
2000年 | 2484篇 |
1999年 | 1901篇 |
1998年 | 730篇 |
1997年 | 715篇 |
1996年 | 721篇 |
1995年 | 807篇 |
1993年 | 742篇 |
1992年 | 1574篇 |
1991年 | 1768篇 |
1990年 | 1654篇 |
1989年 | 1664篇 |
1988年 | 1482篇 |
1987年 | 1551篇 |
1986年 | 1607篇 |
1985年 | 1560篇 |
1984年 | 1192篇 |
1983年 | 1061篇 |
1982年 | 706篇 |
1979年 | 1160篇 |
1978年 | 896篇 |
1977年 | 755篇 |
1975年 | 780篇 |
1974年 | 1029篇 |
1973年 | 1029篇 |
1972年 | 1044篇 |
1971年 | 997篇 |
1970年 | 991篇 |
1969年 | 905篇 |
1968年 | 811篇 |
1967年 | 799篇 |
1966年 | 733篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
A Yabuki S Suzuki M Matsumot M Kurohmaru Y Hayashi H Nishinakagawa 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2001,63(12):1339-1342
The proximal straight tubules of the female mouse kidney exhibit heavy periodic acid Schiff (PAS) staining in their brush borders and numerous cytoplasmic granules. In the present study, the female DBA/2Cr mouse kidney was examined, using various fixatives (formalin, PFA, PLP, Zamboni's, Bouin, or Carnoy solution) and various staining methods (HE, PAS, alcian blue, periodic acid methenamine-silver (PAM), toluidine blue, azan, or Congo red). Under azan and PAM, the staining pattern of the brush border was similar to that of PAS, and few effects of the fixative were observed. Cytoplasmic granules were clearly detected with PAM as well as PAS. However, these granules were not detected with Carnoy solution. Furthermore, distribution of granules differed between PAS and PAM. 相似文献
2.
E. Conde A. M. Moreno I. Martin-Lacave A. Fernandez y H. Galera 《Anatomia, histologia, embryologia》1992,21(1):94-100
A systematic immunohistochemical study of the ultimobranchial tubule (UBT) has been carried out in 45 Wistar rats of different ages (0, 5, 10, 15, 20, 25, 30, 60 and 120 days). The existence of calcitonin immunoreactive cells in the UBT wall has been demonstrated in a 5-days old rat. In addition, immunohistochemical studies for thyroglobulin revealed positive staining in follicular cells connected to the UBT and, occasionally, in isolated cells lying within solid clusters from the UBT. These last results together with the continued and repeated existence of numerous mitosis and PAS (+) microfollicles, apparently rising from the UBT, support the hypothesis that the ultimobranchial body (UBB) may contribute partially to the formation of a part of the follicular component. 相似文献
3.
Kevin R. Stuart Arnold G. Eversole David E. Brune 《Journal of the World Aquaculture Society》2001,32(1):105-111
Abstract.— The freshwater mussel Elliptio complanata was provided water containing green algae and cyanobacteria delivered from the Partitioned Aquaculture System (PAS) at eight flow rates to determine algal filtration rates as mg of particulate organic carbon (POC)/kg wet tissue weight per h. The dominant taxon in cyanobacterial waters was Microcystis while the dominant taxa in green algal waters were Scenedesmus and Ankistrodesmus . The cell counts of Scenedesmus and Ankistrodesmus were the only algal taxa that were significantly different between the incoming water and water filtered by mussels. Filtration rates of POC obtained from green algal water were significantly greater than from cyanobacteria-dominated waters at all flow rates. A significant increase in mean filtration rate was observed as flow rates increased. The filtration rate of green algae increased as POC concentration increased, peaking at 28 mg C/L. A maximum filtration rate was not observed with cyanobacterial waters. 相似文献
4.
E Oohashi K Yagi Y Uzuka S Tanabe T Sarashina T Ishida 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2001,63(11):1241-1243
The purpose of this study was to evaluate seasonal influences on thyroid hormone levels of healthy outdoor dogs in Hokkaido. We surveyed serum basal total thyroxine (tT4), free thyroxine (fT4), and canine thyroid-stimulating hormone (cTSH) levels, and tT4 levels after administration of TSH for a year. Basal tT4 levels decreased in January, and increased in August and September. fT4 levels increased in January and November. No significant seasonal variation was found in cTSH. tT4 levels after administration of TSH in August and November increased. These results suggested that the thyroid gland may have been activated in November. We should take seasonal variation into consideration when thyroid function is tested. 相似文献
5.
The isolation of (+)-totarol as active compound against Mycobacterium tuberculosis is reported from Chamaecyparis nootkatensis outerbark. 相似文献
6.
7.
8.
9.
10.
Abstract. In field and laboratory experiments the conditioner‘Agri-SC’has shown improvements in the structure of loamy sand soils in east Shropshire, UK. It resulted in statistically significant decreases in soil bulk density values and increases in soil porosity and aggregate stability. Further experiments are in progress on both loamy sand and silt loam soils. 相似文献