全文获取类型
收费全文 | 1358篇 |
免费 | 70篇 |
国内免费 | 2篇 |
专业分类
林业 | 96篇 |
农学 | 35篇 |
基础科学 | 16篇 |
236篇 | |
综合类 | 185篇 |
农作物 | 34篇 |
水产渔业 | 148篇 |
畜牧兽医 | 480篇 |
园艺 | 32篇 |
植物保护 | 168篇 |
出版年
2024年 | 4篇 |
2023年 | 6篇 |
2022年 | 10篇 |
2021年 | 25篇 |
2020年 | 22篇 |
2019年 | 33篇 |
2018年 | 30篇 |
2017年 | 30篇 |
2016年 | 40篇 |
2015年 | 27篇 |
2014年 | 38篇 |
2013年 | 45篇 |
2012年 | 91篇 |
2011年 | 82篇 |
2010年 | 56篇 |
2009年 | 45篇 |
2008年 | 100篇 |
2007年 | 97篇 |
2006年 | 90篇 |
2005年 | 72篇 |
2004年 | 80篇 |
2003年 | 62篇 |
2002年 | 64篇 |
2001年 | 30篇 |
2000年 | 15篇 |
1999年 | 17篇 |
1998年 | 18篇 |
1997年 | 16篇 |
1996年 | 14篇 |
1995年 | 12篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 12篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 13篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1978年 | 4篇 |
1976年 | 5篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1942年 | 3篇 |
排序方式: 共有1430条查询结果,搜索用时 15 毫秒
101.
Service-oriented science 总被引:1,自引:0,他引:1
Foster I 《Science (New York, N.Y.)》2005,308(5723):814-817
New information architectures enable new approaches to publishing and accessing valuable data and programs. So-called service-oriented architectures define standard interfaces and protocols that allow developers to encapsulate information tools as services that clients can access without knowledge of, or control over, their internal workings. Thus, tools formerly accessible only to the specialist can be made available to all; previously manual data-processing and analysis tasks can be automated by having services access services. Such service-oriented approaches to science are already being applied successfully, in some cases at substantial scales, but much more effort is required before these approaches are applied routinely across many disciplines. Grid technologies can accelerate the development and adoption of service-oriented science by enabling a separation of concerns between discipline-specific content and domain-independent software and hardware infrastructure. 相似文献
102.
The lead-lead isochron age of chondrules in the CR chondrite Acfer 059 is 4564.7 +/- 0.6 million years ago (Ma), whereas the lead isotopic age of calcium-aluminum-rich inclusions (CAIs) in the CV chondrite Efremovka is 4567.2 +/- 0.6 Ma. This gives an interval of 2.5 +/- 1.2 million years (My) between formation of the CV CAIs and the CR chondrules and indicates that CAI- and chondrule-forming events lasted for at least 1.3 My. This time interval is consistent with a 2- to 3-My age difference between CR CAIs and chondrules inferred from the differences in their initial 26Al/27Al ratios and supports the chronological significance of the 26Al-26Mg systematics. 相似文献
103.
Moreau JW Weber PK Martin MC Gilbert B Hutcheon ID Banfield JF 《Science (New York, N.Y.)》2007,316(5831):1600-1603
High-spatial-resolution secondary ion microprobe spectrometry, synchrotron radiation-based Fourier-transform infrared spectroscopy, and polyacrylamide gel analysis demonstrated the intimate association of proteins with spheroidal aggregates of biogenic zinc sulfide nanocrystals, an example of extracellular biomineralization. Experiments involving synthetic zinc sulfide nanoparticles and representative amino acids indicated a driving role for cysteine in rapid nanoparticle aggregation. These findings suggest that microbially derived extracellular proteins can limit the dispersal of nanoparticulate metal-bearing phases, such as the mineral products of bioremediation, that may otherwise be transported away from their source by subsurface fluid flow. 相似文献
104.
105.
Owens IP 《Science (New York, N.Y.)》2002,297(5589):2008-2009
106.
农杆菌介导转化为目的的水稻组培体系的建立 总被引:2,自引:2,他引:2
高效可靠的组培再生体系是水稻农杆菌遗传转化的基础。该试验通过对培养基类型、光照条件和水稻基因型的研究,发现富含脯氨酸的N6D培养基能明显促进愈伤组织的生长,光照条件也可显著改善其生长。Calrose76和合系41号被证实为易于组培高效再生的粳稻品种,该高效组培体系的为云南栽培良种合系41号的进一步农杆菌转化体系的建立铺平了道路。 相似文献
107.
108.
Recently developed, high-efficiency, light-emitting diodes use two-dimensional photonic crystals to enhance the extraction of otherwise internally trapped light and multilayer reflectors to control the direction of light emission. This work describes the characterization of a naturally evolved light-extraction system on the wing scales of a small group of Papilio butterflies. The efficient extraction of fluorescence from these scales is facilitated by a two-dimensional photonic crystal slab that uses a multilayer to help control emission direction. Its light-extraction function is analogous to that of the light-emitting diode. 相似文献
109.
110.