全文获取类型
收费全文 | 58738篇 |
免费 | 3298篇 |
国内免费 | 37篇 |
专业分类
林业 | 3051篇 |
农学 | 2213篇 |
基础科学 | 351篇 |
7430篇 | |
综合类 | 6825篇 |
农作物 | 2100篇 |
水产渔业 | 3186篇 |
畜牧兽医 | 32897篇 |
园艺 | 725篇 |
植物保护 | 3295篇 |
出版年
2019年 | 496篇 |
2018年 | 955篇 |
2017年 | 1036篇 |
2016年 | 1007篇 |
2015年 | 866篇 |
2014年 | 1011篇 |
2013年 | 2320篇 |
2012年 | 1806篇 |
2011年 | 2197篇 |
2010年 | 1436篇 |
2009年 | 1369篇 |
2008年 | 2031篇 |
2007年 | 2043篇 |
2006年 | 1932篇 |
2005年 | 1789篇 |
2004年 | 1684篇 |
2003年 | 1667篇 |
2002年 | 1537篇 |
2001年 | 2332篇 |
2000年 | 2186篇 |
1999年 | 1722篇 |
1998年 | 684篇 |
1997年 | 623篇 |
1996年 | 601篇 |
1995年 | 671篇 |
1994年 | 572篇 |
1993年 | 558篇 |
1992年 | 1262篇 |
1991年 | 1397篇 |
1990年 | 1450篇 |
1989年 | 1331篇 |
1988年 | 1244篇 |
1987年 | 1231篇 |
1986年 | 1167篇 |
1985年 | 1104篇 |
1984年 | 917篇 |
1983年 | 723篇 |
1982年 | 524篇 |
1979年 | 792篇 |
1978年 | 616篇 |
1977年 | 469篇 |
1976年 | 524篇 |
1975年 | 502篇 |
1974年 | 625篇 |
1973年 | 605篇 |
1972年 | 633篇 |
1971年 | 603篇 |
1970年 | 588篇 |
1969年 | 537篇 |
1967年 | 497篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
73.
74.
75.
76.
P J Ihrke R M Schwartzman K McGinley L N Horwitz R R Marples 《American journal of veterinary research》1978,39(9):1487-1489
Quantitative and qualitative bacterial assays were performed on the skin of 15 normal and 32 seborrheic dogs. Nonionic detergent scrubs were made on areas demarcated by glass sidearm cylinders. Quantitative analysis was accomplished by the serial dilution technique, and the bacteria were identified by individual and colonial morphology and by enzyme production. Areas measured on control dogs had a markedly lower total bacterial count than similar areas measured on seborrheic animals. Control dogs had a flora consisting primarily of coagulase-negative cocci, whereas seborrheic dogs usually had a cutaneous flora composed primarily of Stahylococcus aureus, coagulase-positive. 相似文献
77.
P. VIDHYASEKARAN R. RABINDRAN M. MUTHAMILAN K. NAYAR K. RAJAPPAN N. SUBRAMANIAN & K. VASUMATHI 《Plant pathology》1997,46(3):291-297
Pseudomonas fluorescens strain Pf1, inhibitory to the growth of the rice blast pathogen Pyricularia oryzae in vitro , was developed as a talc-based powder formulation. When rice seeds were treated with this formulation, the bacteria spread to roots, stems and leaves of the plants and protected against leaf infection by P. oryzae . When applied as a foliar spray, the bacteria survived on the leaves. The powder formulation controlled leaf blast under greenhouse conditions. In tests as a seed treatment and foliar spray in four field trials it effectively controlled the disease and increased grain yield. 相似文献
78.
The activity of the ovary-inhibiting hormone in the eyestalks of female prawns, Parapenaeopsis hardwickii, was determined during its ovarian developmental cycle. In the inactive (stage I) and post-spawned phases of ovarian development, the ovary-inhibiting hormone activity was found to be very high. During the phase of full vitellogenesis (stage IV), the inhibiting activity is almost negligible. After spawning (stage V) it is present, but at a lower level than during inactive and post-spawned phases. Hence it is inferred that ovary-inhibiting hormone appears to be responsible for the phase of ovarian quiescence and to control the rate of vitellogenesis. 相似文献
79.
Evolution of C2H4 from soils under anaerobic conditions was stimulated by amendment with cereal straw, but hay had little effect. Temporary restoration of aerobic conditions resulted in large increases in C3 and C4 hydrocarbons, with both straw and hay amendments. Several known products of the fermentative degradation of carbohydrate increased the evolution of hydrocarbons under anaerobic, and to a greater extent, under aerobic conditions. In particular, ethanol and butyric acid promoted the formation of C2H4 and propylene, respectively. The association between degradation products and C2H4 suggests that both may be implicated when root growth is adversely affected by the anaerobic decomposition of plant residues. 相似文献
80.