全文获取类型
收费全文 | 15050篇 |
免费 | 1212篇 |
国内免费 | 1378篇 |
专业分类
林业 | 1456篇 |
农学 | 1913篇 |
基础科学 | 746篇 |
2164篇 | |
综合类 | 4604篇 |
农作物 | 1064篇 |
水产渔业 | 967篇 |
畜牧兽医 | 3154篇 |
园艺 | 505篇 |
植物保护 | 1067篇 |
出版年
2024年 | 42篇 |
2023年 | 233篇 |
2022年 | 400篇 |
2021年 | 485篇 |
2020年 | 550篇 |
2019年 | 580篇 |
2018年 | 480篇 |
2017年 | 612篇 |
2016年 | 562篇 |
2015年 | 682篇 |
2014年 | 765篇 |
2013年 | 814篇 |
2012年 | 944篇 |
2011年 | 1060篇 |
2010年 | 971篇 |
2009年 | 823篇 |
2008年 | 780篇 |
2007年 | 664篇 |
2006年 | 631篇 |
2005年 | 629篇 |
2004年 | 415篇 |
2003年 | 540篇 |
2002年 | 770篇 |
2001年 | 709篇 |
2000年 | 542篇 |
1999年 | 341篇 |
1998年 | 220篇 |
1997年 | 181篇 |
1996年 | 159篇 |
1995年 | 136篇 |
1994年 | 95篇 |
1993年 | 98篇 |
1992年 | 133篇 |
1991年 | 116篇 |
1990年 | 102篇 |
1989年 | 71篇 |
1988年 | 60篇 |
1987年 | 41篇 |
1986年 | 28篇 |
1985年 | 19篇 |
1984年 | 16篇 |
1983年 | 13篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1979年 | 10篇 |
1966年 | 6篇 |
1956年 | 5篇 |
1903年 | 4篇 |
1893年 | 4篇 |
1892年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
143.
144.
Paddy and Water Environment - The combined use of chemical N fertilizer and crop residue could influence greenhouse gas emissions in agriculture. A pot experiment was performed to examine the... 相似文献
145.
全球谷物市场在2011年春节期间的整体走势可谓异常火爆.从节后郑州强麦期货市场首日涨停的“飞天舞”.到国际市场上饲用和优质小麦、期货和现货小麦价格的“比翼双飞”组合.使得国内农户更倾向于挺价待涨。其主要利多题材来自于2010年全球范围内多发的灾害性天气. 相似文献
146.
147.
从‘嘎拉’苹果中克隆了一个MYB转录因子基因(序列号:MDP0000894463)。该基因包含长为729 bp完整的开放阅读框,编码243个氨基酸,预测其蛋白质分子量为26.34 kD,等电点为9.29。系统进化树分析表明,这一MYB转录因子与拟南芥AtMYB73同源序列相似性最高,因此将其命名为MdMYB73。功能域分析表明,MdMYB73蛋白含有保守的R2R3-typeMYB绑定域。荧光定量PCR分析表明,MdMYB73在苹果的各个组织均有表达,在叶片和花中表达相对较高;MdMYB73的表达明显受盐胁迫的诱导。将异位表达MdMYB73的拟南芥幼苗进行抗盐鉴定,结果表明MdMYB73负调控拟南芥盐胁迫抗性;同时,AtSOS1,AtSOS3和AtNHX1抗盐相关基因的表达水平显著降低,表明MdMYB73可能负调控SOS反应,影响拟南芥抵抗高盐胁迫过程。将MdMYB73基因遗传转化苹果愈伤组织,抗盐表型分析表明,MdMYB73过量表达也明显降低了转基因愈伤组织对盐胁迫的抗性。 相似文献
148.
在“共同但有区别的责任”原则下,综合考虑人均累计碳排放相等和差别原则,将中国碳排放划分为历史(1995-2010年)和未来(2011-2050年)两个时期,设计并分析中国各省区的减排框架.结果表明:1)历史时期,中国各省碳排放权呈北亏损,南盈余的基本分布格局;2)未来时期,中国各省碳排放权的分布格局变化不大,但亏损和盈余中心的亏损或盈余比重上升;3)两时期内,东部地区盈余比重显著上升,中部地区亏损比重显著上升;西部地区盈余比重显著下降. 相似文献
149.
150.
张婷袁伟涛郭肖兰王凯英徐超 《动物营养学报》2023,(4):2571-2579
This experiment was conducted to study the effects of dietary lactic acid bacteria (LAB) and fructooligosaccharides (FOS) on growth performance, nutrient digestibility and serum biochemical indices of Arctic foxes (Alopex lagopus) during early growth period. Sixty male post-litter Arctic foxes with the average body weight of (1.16±0.15) kg and at the age of (45±3) days were randomly assigned to 4 groups with 3 replicates per group and 5 foxes per replicate. The foxes were fed the following diets, respectively: basal diet (control group), basal diet+3×109 CFU / kg LAB (LAB group), basal diet+5 g / kg FOS (FOS group) and basal diet+3×109 CFU / kg LAB+5 g / kg FOS (LAB+FOS group). The experiment lasted for 30 days. The results showed as follows: 1) on the days 1 to 15, the diarrhea rate of foxes in the LAB group and LAB+FOS group was significantly lower than that in the control group and FOS group (P<0.05). On the days 16 to 30, the average daily gain of foxes in the LAB+FOS group was significantly higher than that in the control group and FOS group (P<0.05), but had no significant difference with LAB group (P>0.05); the diarrhea rate of foxes in the LAB+FOS group was significantly lower than that in the control group and FOS group (P<0.05), but had no significant difference with LAB group (P>0.05); compared with the FOS group, the feed to gain ratio of foxes in the LAB+FOS group was significantly decreased (P<0.05). 2) The dry matter digestibility of foxes in the LAB + FOS group was significantly higher than that in the control group and FOS group (P < 0.05), but had no significant difference with LAB group (P>0.05). There were no significant differences in nitrogen intake, fecal nitrogen, urine nitrogen, nitrogen deposition, net protein utilization and protein biological value among all groups (P>0.05). 3) Serum total protein (TP) content of foxes in the LAB+FOS group was significantly higher than that in the FOS group (P<0.05), but had no significant difference with control group and LAB group (P>0.05). Serum albumin (ALB) content of foxes in the LAB group was significantly higher than that in the control group and FOS group (P<0.05), but had no significant difference with LAB+ FOS group (P>0.05). Serum urea nitrogen (UN) content of foxes in the LAB+FOS group was significantly decreased compared with the control group (P < 0. 05). In conclusion, the combined supplementation of 3 × 109 CFU / kg LAB and 5 g / kg FOS in the diet is beneficial to reduce diarrhea rate, improve dry matter digestibility, improve body immune level, and promote the growth of Arctic foxes during early growth period. © 2023 Chinese Journal of Urology. All rights reserved. 相似文献