全文获取类型
收费全文 | 1014篇 |
免费 | 65篇 |
国内免费 | 1篇 |
专业分类
林业 | 46篇 |
农学 | 34篇 |
基础科学 | 4篇 |
114篇 | |
综合类 | 260篇 |
农作物 | 55篇 |
水产渔业 | 48篇 |
畜牧兽医 | 453篇 |
园艺 | 9篇 |
植物保护 | 57篇 |
出版年
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 12篇 |
2020年 | 19篇 |
2019年 | 27篇 |
2018年 | 17篇 |
2017年 | 25篇 |
2016年 | 20篇 |
2015年 | 17篇 |
2014年 | 28篇 |
2013年 | 42篇 |
2012年 | 46篇 |
2011年 | 49篇 |
2010年 | 32篇 |
2009年 | 26篇 |
2008年 | 51篇 |
2007年 | 49篇 |
2006年 | 32篇 |
2005年 | 43篇 |
2004年 | 38篇 |
2003年 | 47篇 |
2002年 | 35篇 |
2001年 | 25篇 |
2000年 | 23篇 |
1999年 | 19篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 14篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 14篇 |
1988年 | 15篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 13篇 |
1984年 | 7篇 |
1983年 | 13篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 14篇 |
1975年 | 11篇 |
1974年 | 7篇 |
1972年 | 5篇 |
1970年 | 7篇 |
1969年 | 7篇 |
1968年 | 7篇 |
排序方式: 共有1080条查询结果,搜索用时 15 毫秒
71.
Implantation of genetically engineered fibroblasts into mice: implications for gene therapy 总被引:7,自引:0,他引:7
R F Selden M J Skoskiewicz K B Howie P S Russell H M Goodman 《Science (New York, N.Y.)》1987,236(4802):714-718
In a variety of human genetic diseases, replacement of the absent or defective protein provides significant therapeutic benefits. As a model for a somatic cell gene therapy system, cultured murine fibroblasts were transfected with a human growth hormone (hGH) fusion gene and cells from one of the resulting clonal lines were subsequently implanted into various locations in mice. Such implants synthesized and secreted hGH, which was detectable in the serum. The function of the implants depended on their location and size, and on the histocompatibility of the donor cells with their recipients. The expression of hGH could be modified by addition of regulatory effectors, and, with appropriate immunosuppression, the implants survived for more than 3 months. This approach to gene therapy, here termed "transkaryotic implantation," is potentially applicable to many genetic diseases in that the transfected cell line can be extensively characterized prior to implantation, several anatomical sites are suitable for implantation, and regulated expression of the gene of therapeutic interest can be obtained. 相似文献
72.
Diphosphonates inhibit formation of calcium phosphate crystals in vitro and pathological calcification in vivo 总被引:14,自引:0,他引:14
Two diphosphonates containing the P-C-P bond, CH(3)C(OH)(PO(3)HNa)(2) and H(2)C(PO(3)HNa)(2), inhibit the crystallization of calcium phosphate in vitro and prevent aortic calcification of rats given large amounts of vitamin D(3). The diphosphonates therefore have effects similar to those described for compounds containing the P-O-P bond but are active when administered orally. 相似文献
73.
74.
Nadeau JH Balling R Barsh G Beier D Brown SD Bucan M Camper S Carlson G Copeland N Eppig J Fletcher C Frankel WN Ganten D Goldowitz D Goodnow C Guenet JL Hicks G Hrabe de Angelis M Jackson I Jacob HJ Jenkins N Johnson D Justice M Kay S Kingsley D Lehrach H Magnuson T Meisler M Poustka A Rinchik EM Rossant J Russell LB Schimenti J Shiroishi T Skarnes WC Soriano P Stanford W Takahashi JS Wurst W Zimmer A;International Mouse Mutagenesis Consortium 《Science (New York, N.Y.)》2001,291(5507):1251-1255
75.
Gamblin SJ Haire LF Russell RJ Stevens DJ Xiao B Ha Y Vasisht N Steinhauer DA Daniels RS Elliot A Wiley DC Skehel JJ 《Science (New York, N.Y.)》2004,303(5665):1838-1842
The 1918 influenza pandemic resulted in about 20 million deaths. This enormous impact, coupled with renewed interest in emerging infections, makes characterization of the virus involved a priority. Receptor binding, the initial event in virus infection, is a major determinant of virus transmissibility that, for influenza viruses, is mediated by the hemagglutinin (HA) membrane glycoprotein. We have determined the crystal structures of the HA from the 1918 virus and two closely related HAs in complex with receptor analogs. They explain how the 1918 HA, while retaining receptor binding site amino acids characteristic of an avian precursor HA, is able to bind human receptors and how, as a consequence, the virus was able to spread in the human population. 相似文献
76.
Overexpression of low density lipoprotein (LDL) receptor eliminates LDL from plasma in transgenic mice 总被引:26,自引:0,他引:26
S L Hofmann D W Russell M S Brown J L Goldstein R E Hammer 《Science (New York, N.Y.)》1988,239(4845):1277-1281
A complementary DNA encoding the human low density lipoprotein (LDL) receptor under control of the mouse metallothionein-I promoter was injected into fertilized mouse eggs, and a strain of mice expressing high levels of LDL receptors was established. After administration of cadmium, these mice cleared intravenously injected 125I-labeled LDL from blood eight to ten times more rapidly than did normal mice. The plasma concentrations of apoproteins B-100 and E, the two ligands for the LDL receptor, declined by more than 90 percent after cadmium treatment, but the concentration of another apoprotein, A-I, was unaffected. Therefore, overexpression of an endocytotic receptor can dramatically lower the ambient concentration of its ligand in vivo. 相似文献
77.
A mutualistic association between a fungal endophyte and a tropical panic grass allows both organisms to grow at high soil temperatures. We characterized a virus from this fungus that is involved in the mutualistic interaction. Fungal isolates cured of the virus are unable to confer heat tolerance, but heat tolerance is restored after the virus is reintroduced. The virus-infected fungus confers heat tolerance not only to its native monocot host but also to a eudicot host, which suggests that the underlying mechanism involves pathways conserved between these two groups of plants. 相似文献
78.
Russell CA Jones TC Barr IG Cox NJ Garten RJ Gregory V Gust ID Hampson AW Hay AJ Hurt AC de Jong JC Kelso A Klimov AI Kageyama T Komadina N Lapedes AS Lin YP Mosterin A Obuchi M Odagiri T Osterhaus AD Rimmelzwaan GF Shaw MW Skepner E Stohr K Tashiro M Fouchier RA Smith DJ 《Science (New York, N.Y.)》2008,320(5874):340-346
Antigenic and genetic analysis of the hemagglutinin of approximately 13,000 human influenza A (H3N2) viruses from six continents during 2002-2007 revealed that there was continuous circulation in east and Southeast Asia (E-SE Asia) via a region-wide network of temporally overlapping epidemics and that epidemics in the temperate regions were seeded from this network each year. Seed strains generally first reached Oceania, North America, and Europe, and later South America. This evidence suggests that once A (H3N2) viruses leave E-SE Asia, they are unlikely to contribute to long-term viral evolution. If the trends observed during this period are an accurate representation of overall patterns of spread, then the antigenic characteristics of A (H3N2) viruses outside E-SE Asia may be forecast each year based on surveillance within E-SE Asia, with consequent improvements to vaccine strain selection. 相似文献
79.
80.