全文获取类型
收费全文 | 669818篇 |
免费 | 76322篇 |
国内免费 | 298篇 |
专业分类
746438篇 |
出版年
2018年 | 5796篇 |
2016年 | 7803篇 |
2015年 | 10532篇 |
2014年 | 12314篇 |
2013年 | 18175篇 |
2012年 | 20199篇 |
2011年 | 20389篇 |
2010年 | 13826篇 |
2009年 | 12604篇 |
2008年 | 18224篇 |
2007年 | 18812篇 |
2006年 | 17863篇 |
2005年 | 17061篇 |
2004年 | 17015篇 |
2003年 | 16522篇 |
2002年 | 16124篇 |
2001年 | 29632篇 |
2000年 | 29810篇 |
1999年 | 24141篇 |
1998年 | 8636篇 |
1997年 | 8970篇 |
1996年 | 8635篇 |
1995年 | 8006篇 |
1994年 | 8164篇 |
1993年 | 7964篇 |
1992年 | 20503篇 |
1991年 | 19721篇 |
1990年 | 19614篇 |
1989年 | 19268篇 |
1988年 | 17763篇 |
1987年 | 16947篇 |
1986年 | 15648篇 |
1985年 | 15753篇 |
1984年 | 12947篇 |
1983年 | 11299篇 |
1982年 | 8793篇 |
1981年 | 7794篇 |
1980年 | 7484篇 |
1979年 | 12726篇 |
1978年 | 9759篇 |
1977年 | 8943篇 |
1976年 | 8476篇 |
1975年 | 9203篇 |
1974年 | 9784篇 |
1973年 | 9769篇 |
1972年 | 8922篇 |
1971年 | 8115篇 |
1970年 | 7073篇 |
1969年 | 6707篇 |
1968年 | 6010篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
A D Ado R M Zolotareva B M Zolotarev 《Biulleten' eksperimental'no? biologii i meditsiny》1986,102(9):377-379
Method has been modified and used for quantitative gas chromatographic determination of microtraces in a large volume of test mixture under study. The method can be applied for the differentiated determination of genuine and false blood cholinesterase by final products of specific substrate hydrolysis. 相似文献
993.
994.
P.Mick Richardson 《Biochemical Systematics and Ecology》1982,10(2):197-199
Published results of the distribution of anthocyanins in the Sterculiaceae have been re-interpreted on the basis of the phylogenetic status of the compounds present. A flavonoid score system was less useful than a cladistic interpretation based on Hennigian arguments. 相似文献
995.
996.
Sequences related to the major subunit gene fedA of F107 fimbriae in porcine Escherichia coli strains that express adhesive fimbriae 总被引:1,自引:0,他引:1
Abstract Porcine Escherichia coli strains isolated from cases fo postweaning diarrhea or edema disease were analysed for the presence of fedA , the major subunit gene of F107 fimbriae. The E. coli isolates were known to contain colonisation factor '8813', or to express F107, 2134P or other fimbriae, different from F4, F5, F6, and F41. PCR with fedA -specific primers, restriction enzyme digestion of the PCR product, and nucleotide sequence analysis demonstrated that 2134P pili, colonisation factor '8813' and fimbriae identified on Australian strains of the O141 serotype belong to one family of F107 fimbrial antigens. 相似文献
997.
Noni (Morinda citrifolia) is increasing in worldwide popularity as a food or dietary supplement with versatile health benefits. The aim of this study was to investigate the effects of Noni fruit on anxiety symptoms in vitro. To this end, a competitive GABAa receptor-binding assay was developed. Our preliminary study indicates that the methanol crude extract of Noni fruit showed significant affinity to the gamma-aminobutyric acid A (GABAa) inhibitory neurotransmitter receptors, and displayed 75% binding inhibition of the agonist radioligand [3H] muscimol at a concentration of 100 microg/ml. Further experiments demonstrated that the MeOH extract, and its BuOH and H2O partitions, exhibited IC50 values of 22.8, 27.2, and 17.1 microg/ml, respectively, in the GABAa-binding assay. Experimental results with Noni fruit indicate the presence of competitive ligand(s), which may bind to the GABAa receptor as an agonist, and thus induce its anxiolytic and sedative effects. The study provides an in vitro rationale for one of Noni's versatile and traditional uses. In addition, an HPLC fingerprint profile of the methanolic extract of Noni fruit has been established for quality control purpose. 相似文献
998.
999.
1000.