全文获取类型
收费全文 | 2802篇 |
免费 | 276篇 |
出版年
2023年 | 15篇 |
2022年 | 21篇 |
2021年 | 69篇 |
2020年 | 47篇 |
2019年 | 52篇 |
2018年 | 47篇 |
2017年 | 62篇 |
2016年 | 74篇 |
2015年 | 122篇 |
2014年 | 160篇 |
2013年 | 194篇 |
2012年 | 229篇 |
2011年 | 219篇 |
2010年 | 126篇 |
2009年 | 105篇 |
2008年 | 150篇 |
2007年 | 167篇 |
2006年 | 164篇 |
2005年 | 139篇 |
2004年 | 127篇 |
2003年 | 105篇 |
2002年 | 98篇 |
2001年 | 39篇 |
2000年 | 43篇 |
1999年 | 38篇 |
1998年 | 45篇 |
1997年 | 23篇 |
1996年 | 18篇 |
1995年 | 20篇 |
1994年 | 15篇 |
1993年 | 22篇 |
1992年 | 29篇 |
1991年 | 22篇 |
1990年 | 22篇 |
1989年 | 16篇 |
1988年 | 14篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 7篇 |
1984年 | 13篇 |
1983年 | 9篇 |
1981年 | 15篇 |
1979年 | 14篇 |
1978年 | 11篇 |
1977年 | 8篇 |
1976年 | 12篇 |
1975年 | 7篇 |
1972年 | 11篇 |
1970年 | 8篇 |
1882年 | 6篇 |
排序方式: 共有3078条查询结果,搜索用时 31 毫秒
1.
C. Sanderson 《BMJ (Clinical research ed.)》1974,1(5901):245-246
2.
3.
4.
Exposure of human lymphocytes to ionizing radiation reduces mutagenesis by subsequent ionizing radiation 总被引:3,自引:0,他引:3
The effect of prior incubation with [3H]thymidine on survival and mutagenesis after X-irradiation of human lymphocytes was studied by incubating lymphocytes with 0.001-1.0 mu Ci/ml [3H]thymidine for 6 h at 37 degrees C and then irradiating with 150 or 300 rad. Survival was measured using lymphocyte cloning and mutagenesis was measured using 6-thioguanine selection to detect clones mutated at the hypoxanthine phosphoribosyltransferase locus. [3H]Thymidine alone had no effect on survival or mutagenesis and X-radiation alone produced the expected decrease in survival and increase in mutations. [3H]Thymidine prior to X-radiation had no effect on lethality of X-radiation but at concentrations of 0.1 and 1.0 mu Ci/ml produced a significant decrease in the number of mutations induced after both 150 and 300 rad. The results suggest that ionizing radiation, produced by disintegration of 3H, reduces the mutagenic effect of a subsequent exposure to ionizing radiation by induction of a system which prevents or repairs a restricted class of radiation damage. 相似文献
5.
Karlheinz Grillitsch Pablo Tarazona Lisa Klug Tamara Wriessnegger Günther Zellnig Erich Leitner Ivo Feussner Günther Daum 《生物化学与生物物理学报:生物膜》2014
Despite similarities of cellular membranes in all eukaryotes, every compartment displays characteristic and often unique features which are important for the functions of the specific organelles. In the present study, we biochemically characterized the plasma membrane of the methylotrophic yeast Pichia pastoris with emphasis on the lipids which form the matrix of this compartment. Prerequisite for this effort was the design of a standardized and reliable isolation protocol of the plasma membrane at high purity. Analysis of isolated plasma membrane samples from P. pastoris revealed an increase of phosphatidylserine and a decrease of phosphatidylcholine compared to bulk membranes. The amount of saturated fatty acids in the plasma membrane was higher than in total cell extracts. Ergosterol, the final product of the yeast sterol biosynthetic pathway, was found to be enriched in plasma membrane fractions, although markedly lower than in Saccharomyces cerevisiae. A further characteristic feature of the plasma membrane from P. pastoris was the enrichment of inositol phosphorylceramides over neutral sphingolipids, which accumulated in internal membranes. The detailed analysis of the P. pastoris plasma membrane is discussed in the light of cell biological features of this microorganism especially as a microbial cell factory for heterologous protein production. 相似文献
6.
7.
8.
Anton Pauw Sunshine A. Van Bael Halton A. Peters Steven D. Allison José L. C. Camargo Miguel Cifuentes-Jara Aurlstela Conserva Teresa Garcia Restom Tamara Heartsill-Scalley Scott A. Mangan Gabriela Nunez-lturri Elsie Rivera-Ocasio Mark Rountree Susanne Vetter Carolina Volkmer de Castllho 《Biotropica》2004,36(3):410-413
9.
Crystal and solution structures of the oligonucleotide d(ATGCGCAT)2: a combined X-ray and NMR study. 总被引:4,自引:1,他引:3
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
G R Clark D G Brown M R Sanderson T Chwalinski S Neidle J M Veal R L Jones W D Wilson G Zon E Garman 《Nucleic acids research》1990,18(18):5521-5528
A combined crystal-structure determination and NMR analysis of the octanucleotide d(ATGCGCAT)2 is reported. The X-ray analysis shows that the structure is A-form duplex in crystal state. The NMR study shows that in solution this sequence is B-type. The conformational results from each technique are presented in detail. The implications of these findings in terms of conformational flexibility and ligand binding are discussed. 相似文献
10.