全文获取类型
收费全文 | 2031篇 |
免费 | 127篇 |
国内免费 | 1篇 |
专业分类
林业 | 86篇 |
农学 | 47篇 |
基础科学 | 7篇 |
207篇 | |
综合类 | 476篇 |
农作物 | 84篇 |
水产渔业 | 163篇 |
畜牧兽医 | 944篇 |
园艺 | 42篇 |
植物保护 | 103篇 |
出版年
2023年 | 24篇 |
2022年 | 33篇 |
2021年 | 43篇 |
2020年 | 66篇 |
2019年 | 71篇 |
2018年 | 42篇 |
2017年 | 59篇 |
2016年 | 45篇 |
2015年 | 40篇 |
2014年 | 49篇 |
2013年 | 69篇 |
2012年 | 132篇 |
2011年 | 122篇 |
2010年 | 65篇 |
2009年 | 63篇 |
2008年 | 107篇 |
2007年 | 104篇 |
2006年 | 107篇 |
2005年 | 113篇 |
2004年 | 90篇 |
2003年 | 74篇 |
2002年 | 69篇 |
2001年 | 26篇 |
2000年 | 30篇 |
1999年 | 18篇 |
1998年 | 18篇 |
1997年 | 7篇 |
1996年 | 16篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1993年 | 41篇 |
1992年 | 19篇 |
1991年 | 21篇 |
1990年 | 19篇 |
1989年 | 21篇 |
1988年 | 16篇 |
1987年 | 12篇 |
1986年 | 20篇 |
1985年 | 14篇 |
1984年 | 47篇 |
1983年 | 22篇 |
1981年 | 7篇 |
1979年 | 14篇 |
1973年 | 8篇 |
1972年 | 8篇 |
1971年 | 14篇 |
1970年 | 14篇 |
1968年 | 7篇 |
1967年 | 8篇 |
1966年 | 6篇 |
排序方式: 共有2159条查询结果,搜索用时 15 毫秒
151.
152.
Stebbins JF 《Science (New York, N.Y.)》2002,297(5585):1285-1287
153.
154.
A coalition of environmental groups headed by activist Jeremy Rifkin has filed lawsuits to halt experiments that would release genetically engineered organisms into the environment. One suit, filed against the National Institutes of Health on 14 September 1983, would block tests by researchers at the University of California, Berkeley. A second suit, filed 16 September 1983 against Cetus Madison and BioTechnica, seeks to halt field tests that had been approved by NIH's Recombinant DNA Advisory Committee. At issue are NIH's role in evaluating the risks of genetic experimentation, and the public's right of access to proprietary information. 相似文献
155.
Dilution of a photochemical system containing hydrocarbons and oxides of nitrogen can lead to higher ozone concentrations than are observed in a static system. This effect was observed in an outdoor smog chamber with a hydrocarbon mix simulating urban systems. 相似文献
156.
Endocannabinoid hydrolysis generates brain prostaglandins that promote neuroinflammation 总被引:2,自引:0,他引:2
Nomura DK Morrison BE Blankman JL Long JZ Kinsey SG Marcondes MC Ward AM Hahn YK Lichtman AH Conti B Cravatt BF 《Science (New York, N.Y.)》2011,334(6057):809-813
Phospholipase A(2)(PLA(2)) enzymes are considered the primary source of arachidonic acid for cyclooxygenase (COX)-mediated biosynthesis of prostaglandins. Here, we show that a distinct pathway exists in brain, where monoacylglycerol lipase (MAGL) hydrolyzes the endocannabinoid 2-arachidonoylglycerol to generate a major arachidonate precursor pool for neuroinflammatory prostaglandins. MAGL-disrupted animals show neuroprotection in a parkinsonian mouse model. These animals are spared the hemorrhaging caused by COX inhibitors in the gut, where prostaglandins are instead regulated by cytosolic PLA(2). These findings identify MAGL as a distinct metabolic node that couples endocannabinoid to prostaglandin signaling networks in the nervous system and suggest that inhibition of this enzyme may be a new and potentially safer way to suppress the proinflammatory cascades that underlie neurodegenerative disorders. 相似文献
157.
Climate data are dramatically increasing in volume and complexity, just as the users of these data in the scientific community and the public are rapidly increasing in number. A new paradigm of more open, user-friendly data access is needed to ensure that society can reduce vulnerability to climate variability and change, while at the same time exploiting opportunities that will occur. 相似文献
158.
159.
160.