全文获取类型
收费全文 | 700篇 |
免费 | 77篇 |
出版年
2023年 | 7篇 |
2022年 | 12篇 |
2021年 | 14篇 |
2020年 | 8篇 |
2019年 | 7篇 |
2018年 | 20篇 |
2017年 | 16篇 |
2016年 | 20篇 |
2015年 | 34篇 |
2014年 | 47篇 |
2013年 | 56篇 |
2012年 | 49篇 |
2011年 | 59篇 |
2010年 | 38篇 |
2009年 | 34篇 |
2008年 | 33篇 |
2007年 | 52篇 |
2006年 | 34篇 |
2005年 | 38篇 |
2004年 | 29篇 |
2003年 | 32篇 |
2002年 | 21篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 5篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1970年 | 4篇 |
1969年 | 2篇 |
1856年 | 2篇 |
1855年 | 3篇 |
排序方式: 共有777条查询结果,搜索用时 31 毫秒
1.
2.
3.
W Tymiński E Czestochowska A Hellmann A Kreglewski 《Folia haematologica (Leipzig, Germany : 1928)》1980,107(2):269-272
Coagulation and fibrinolysis were measured in the portal and peripheral circulation in 15 rabbits after ligation of the superior mesenteric artery. It was found that the local coagulation syndrome in the mesenteric region can be recognized by tests in blood samples taken from the peripheral circulation area. 相似文献
4.
H J Gabius A Bardosi S Gabius K P Hellmann M Karas H Kratzin 《Biochemical and biophysical research communications》1989,163(1):506-512
A Ca2+-dependent sialic acid-binding protein was purified on fetuin-Sepharose from various types of human tissue. The molecular mass was determined to be 10,315 Da by laser desorption mass spectrometry. Partial sequence analysis after cyanogen bromide cleavage that yielded one N-terminus accessible for Edman degradation revealed an identity to an internal stretch following the only methionine residue within a putative amino acid sequence (Mr 10,048), deduced from the cDNA of a cell cycle-specific gene. The reported biochemical identification is a prerequisite to infer the biological role of the so far undetected gene product. Initial glycohistochemical studies with sialic acid-(BSA-biotin) raised evidence for nuclear localization of sialic acid-binding sites that might reflect, at least in part, detection of this protein. 相似文献
5.
6.
7.
Recombinant human interleukin 1 alpha: purification and biological characterization 总被引:29,自引:0,他引:29
U Gubler A O Chua A S Stern C P Hellmann M P Vitek T M DeChiara W R Benjamin K J Collier M Dukovich P C Familletti 《Journal of immunology (Baltimore, Md. : 1950)》1986,136(7):2492-2497
Interleukin 1 (IL 1) is a polypeptide hormone produced by activated macrophages that affects many different cell types involved in immune and inflammatory responses. The cloning and expression of a murine IL 1 cDNA in Escherichia coli encoding a polypeptide precursor of 270 amino acids has been reported, and expression of the carboxy-terminal 156 amino acids of this precursor in E. coli yields biologically active IL 1. By using the murine IL 1 cDNA as a probe, we have isolated its human homolog from cDNA generated to lipopolysaccharide-stimulated human leukocyte mRNA. Nucleotide sequence analysis of this cDNA predicts a protein of analysis of this cDNA predicts a protein of 271 amino acids (termed IL 1 alpha) which shows congruent to 61% homology to its murine counterpart but only 27% homology to a recently characterized human IL 1 precursor (IL 1 beta). We have expressed the carboxy-terminal 154 amino acids of IL 1 alpha in E. coli, purified this protein to homogeneity, and have compared it with pure recombinant murine IL 1 in several different IL 1 assays based on murine and human cells. Recombinant IL 1 is capable of stimulating T cell and fibroblast proliferation and inducing fibroblast collagenase and prostaglandin production, thus proving that a single molecule has many of the activities previously ascribed to only partially purified IL 1 preparations. Our results indicate that there exists a family of at least two human IL 1 genes (alpha and beta) whose dissimilar protein products have similar biological activities. 相似文献
8.
Protoplasten aus Zellkulturen vonDaucus carota 总被引:1,自引:1,他引:0
Summary Treatment of long-term tissue cultures of carrots and of adventive embryos in these cultures with Cellulase Onozuka P 1500 and with this enzyme + Macerocym resulted in high yields of protoplasts which could be cultivated over prolonged periods (up to 5 months) in a synthetic medium + 0.6 m sorbitol. During cultivation the size of the protoplasts increased considerably ( up to 10 times) and a high percentage of multinucleate (between 2 and 13 nuclei) protoplasts were formed. However no fusion and no regeneration of cell walls were observed. 相似文献
9.
Nadja Zimmer Elisabeth Göttert Joachim Kraus Klaus D. Zang Wolfram Henn 《Human genetics》1993,91(4):317-320
Chromosomal mosaicism in chorionic villus samples (CVS) may arise from different sources, such as clonal diversity within the chorionic tissue or contamination with maternal cells. To determine the origin of karyotyped cells, we compared the immunocytochemical features of mitotic cells in CVS long-term cultures with histological sections of their tissue of origin, i.e. chorionic villi. Immunolabelling of intermediate filaments specific for epithelial cells (cytokeratin) and mesenchymal cells (vimentin) established that mitoses yielded from CVS long-term cultures indeed stem from independently growing clones derived from both the epithelial and mesenchymal parts of the chorionic villi. Thus, mosaicism in CVS cultures may reflect true genetic heterogeneity within the biopsy. However, epithelial chorionic cells undergo in vitro metaplasia leading to co-expression of cytokeratins and vimentin. Fetal-specific immune markers (-HCG and SP1-glycoprotein) are not reliably expressed in CVS cell culture. 相似文献
10.
The Brazilian Federal Senate created a Parliamentary Inquiry Commission (CPI) to investigate the Bolsonaro government's irregularities in the management of the COVID-19 pandemic. One of the cases that drew attention was the research conducted by Prevent Senior, a private health insurance company, on the early treatment of COVID-19. The article analyzes the scientific validity of the research and the ethical problems related to its implementation. It is based on analysis of Prevent Senior's report of the clinical study, the Brazilian and USA clinical trial registries, the Senate's CPI report, and on the information reported by the media. This case of scientific fraud and political-ideological bias exemplifies how Prevent Senior, using a questionable protocol to enhance its reputation and gain government support, was instrumental in building the “early treatment” narrative for COVID-19, and shows how it served as a basis for a government public policy that promoted the use of ineffective drugs. 相似文献