全文获取类型
收费全文 | 2687篇 |
免费 | 288篇 |
专业分类
2975篇 |
出版年
2021年 | 40篇 |
2020年 | 23篇 |
2019年 | 23篇 |
2018年 | 40篇 |
2017年 | 37篇 |
2016年 | 53篇 |
2015年 | 85篇 |
2014年 | 100篇 |
2013年 | 111篇 |
2012年 | 139篇 |
2011年 | 141篇 |
2010年 | 90篇 |
2009年 | 69篇 |
2008年 | 89篇 |
2007年 | 115篇 |
2006年 | 101篇 |
2005年 | 91篇 |
2004年 | 103篇 |
2003年 | 112篇 |
2002年 | 120篇 |
2001年 | 89篇 |
2000年 | 79篇 |
1999年 | 66篇 |
1998年 | 51篇 |
1997年 | 41篇 |
1996年 | 51篇 |
1995年 | 39篇 |
1994年 | 32篇 |
1993年 | 52篇 |
1992年 | 60篇 |
1991年 | 68篇 |
1990年 | 53篇 |
1989年 | 54篇 |
1988年 | 34篇 |
1987年 | 37篇 |
1986年 | 44篇 |
1985年 | 42篇 |
1984年 | 27篇 |
1983年 | 22篇 |
1982年 | 30篇 |
1981年 | 28篇 |
1979年 | 24篇 |
1978年 | 21篇 |
1977年 | 23篇 |
1976年 | 17篇 |
1975年 | 15篇 |
1974年 | 22篇 |
1973年 | 16篇 |
1972年 | 15篇 |
1969年 | 16篇 |
排序方式: 共有2975条查询结果,搜索用时 15 毫秒
11.
TenVibrio anguillarum strains were selected for an immunoelectrophoretic study. Evidence was provided for existence of two new K antigens which displayed cross-reactivity. The importance of an exact characterization of surface antigens inV. anguillarum is considered. 相似文献
12.
Acardiac fetus in a triplet pregnancy 总被引:1,自引:0,他引:1
The acardiac monster represents one of the most severe but rare congenital anomalies. It occurs only in multiple gestations associated with vascular anastomoses between the affected fetus and its co-twin. The prenatal diagnosis of an acardiac fetus must be suspected in any multiple gestation in which cardiac activity cannot be documented sonographically in a growing fetus. We report an acardiac fetus occurring in a spontaneously conceived triplet pregnancy. A review of the literature, including pathogenetic theories and sonographic reports, is discussed. 相似文献
13.
14.
15.
16.
Identity of the two 8S RNA components of the mouse sarcoma virus (Moloney) 总被引:1,自引:0,他引:1 下载免费PDF全文
Larsen CJ Ravicovitch RE Hampe A Mauchauffe M Bazilier M Robert-Robin J 《Nucleic acids research》1974,1(7):849-854
The two 8S A and B RNAs of the Mouse Sarcoma Virus (Moloney) can be converted by heating into a homogeneous population. After digestion with T1 RNAse, they give identical fingerprints. It is concluded that these two molecules represent conformational isomers of the same molecular species. 相似文献
17.
Mucous cysts of the fingers 总被引:1,自引:0,他引:1
E Constant J R Royer R J Pollard R D Larsen J L Posch 《Plastic and reconstructive surgery》1969,43(3):241-246
18.
19.
20.
Production and characterization of recombinant human neutrophil chemotactic factor 总被引:15,自引:0,他引:15
R Furuta J Yamagishi H Kotani F Sakamoto T Fukui Y Matsui Y Sohmura M Yamada T Yoshimura C G Larsen 《Journal of biochemistry》1989,106(3):436-441
A putative mature human neutrophil chemotactic factor (NCF) corresponding to the C-terminal 72 amino acids of its precursor was directly produced in Escherichia coli by recombinant DNA technology. Human NCF was present in both the soluble and insoluble protein fractions of the homogenate of host cells, and it was partially purified as a water-soluble polypeptide from both fractions, separately. The partially purified NCF preparation was highly purified to an endotoxin-free homogeneous polypeptide by means of CM-Sepharose CL-6B column chromatography and gel filtration on Toyopearl HW-55. No difference between the human NCF preparations purified from both starting materials could be found concerning purity, primary structure, solubility, molecular weight, and chemotactic activity for human neutrophils. The amino acid sequence of recombinant human NCF was identical to the sequence deduced from the cDNA sequence. A methionine residue due to the translation initiation codon was removed. Recombinant human NCF was found to be biologically active and to exhibit chemotactic activity for human neutrophils in vitro and cause a neutrophil infiltration in vivo in mice. 相似文献