全文获取类型
收费全文 | 3571篇 |
免费 | 48篇 |
国内免费 | 364篇 |
出版年
2023年 | 7篇 |
2022年 | 5篇 |
2021年 | 15篇 |
2020年 | 3篇 |
2019年 | 14篇 |
2018年 | 19篇 |
2017年 | 13篇 |
2016年 | 23篇 |
2015年 | 37篇 |
2014年 | 188篇 |
2013年 | 246篇 |
2012年 | 178篇 |
2011年 | 115篇 |
2010年 | 103篇 |
2009年 | 142篇 |
2008年 | 184篇 |
2007年 | 195篇 |
2006年 | 219篇 |
2005年 | 222篇 |
2004年 | 209篇 |
2003年 | 206篇 |
2002年 | 200篇 |
2001年 | 135篇 |
2000年 | 117篇 |
1999年 | 122篇 |
1998年 | 81篇 |
1997年 | 108篇 |
1996年 | 87篇 |
1995年 | 96篇 |
1994年 | 126篇 |
1993年 | 89篇 |
1992年 | 83篇 |
1991年 | 67篇 |
1990年 | 57篇 |
1989年 | 52篇 |
1988年 | 37篇 |
1987年 | 35篇 |
1986年 | 22篇 |
1985年 | 28篇 |
1984年 | 33篇 |
1983年 | 11篇 |
1982年 | 20篇 |
1981年 | 15篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1977年 | 4篇 |
1975年 | 1篇 |
1974年 | 2篇 |
排序方式: 共有3983条查询结果,搜索用时 31 毫秒
1.
《Peptides》2015
A new peptide with 61 amino acids cross-linked by 4 disulfide bridges, with molecular weight of 6938.12 Da, and an amidated C-terminal amino acid residue was purified and characterized. The primary structure was obtained by direct Edman degradation and sequencing its gene. The peptide is lethal to mammals and was shown to be similar (95% identity) to toxin Ts1 (gamma toxin) from the Brazilian scorpion Tityus serrulatus; it was named Tt1g (from T. trivittatus toxin 1 gamma-like). Tt1g was assayed on several sub-types of Na+-channels showing displacement of the currents to more negative voltages, being the hNav1.3 the most affected channel. This toxin displays characteristics typical to the β-type sodium scorpion toxins. Lethality tests and physiological assays indicate that this peptide is probably the most important toxic component of this species of scorpion, known for causing human fatalities in the South American continent. 相似文献
2.
3.
R Liang 《Biochemical and biophysical research communications》1984,120(3):741-746
Primary cell cultures were prepared from breast muscles of 11 day 4 hour-embryonic chicks. Cytoplasmic RNAs were isolated from the cultured cells at various time intervals from day 3 to day 8. A [P32] DNA probe complementary to messenger RNA of myosin heavy chain was used to hybridize with the RNAs after gel electrophoresis. A transient species of polyadenylated RNA with a decreased mobility in electrophoresis was detected during a period of time when contractions of syncytial fibers were first observed. 相似文献
4.
5.
6.
In order to investigate gene expression changes associated with cytotoxicity, we used cDNA arrays to monitor the expression
of over 5,000 genes in response to toxic stress in the HepG2 liver cell line. Cells were treated with cytotoxic doses of acetaminophen,
caffeine or thioacetamide for nine time points ranging from 1 to 24 h. Samples of mRNA from each time point were used to prepare
radiolabeled cDNA, which was hybridized to nylon-membrane-based cDNA arrays. High-stringency washes were applied to reduce
cross-hybridization. Analysis of spot intensities revealed that each compound led to approximately 150-250 gene expression
changes that were sustained over at least three adjacent time points. The affected genes could be classified into clusters
based on their temporal patterns of differential expression. A common set of 44 genes showed similar expression changes in
response to all three compounds. Of these changes, 90% could be confirmed by quantitative RT-PCR analysis. The results indicate
that detailed array-based time-course studies, coupled with a sensitive and highly specific confirmation assay, provide a
powerful means of identifying cytotoxicity-associated gene expression changes.
Electronic Publication 相似文献
7.
We isolated a Zea mays cDNA encoding the 40S subunit cytoplasmic ribosomal protein S11. The nucleotide sequence was determined and the derived amino acid sequence compared to the corresponding Arabidopsis thaliana protein showing an homology of 90%. This ribosomal protein is encoded by a small multigene family of at least two members. The mRNA steady-state level is about one order of magnitude higher in rapidly growing parts of the plant such as the roots and shoots of seedlings compared to fully expanded leaf tissue. 相似文献
8.
9.
Sang-Im Yun Byung-Hak Song Jin-Kyoung Kim Young-Min Lee 《Journal of visualized experiments : JoVE》2015,(106)
Reverse genetics, an approach to rescue infectious virus entirely from a cloned cDNA, has revolutionized the field of positive-strand RNA viruses, whose genomes have the same polarity as cellular mRNA. The cDNA-based reverse genetics system is a seminal method that enables direct manipulation of the viral genomic RNA, thereby generating recombinant viruses for molecular and genetic studies of both viral RNA elements and gene products in viral replication and pathogenesis. It also provides a valuable platform that allows the development of genetically defined vaccines and viral vectors for the delivery of foreign genes. For many positive-strand RNA viruses such as Japanese encephalitis virus (JEV), however, the cloned cDNAs are unstable, posing a major obstacle to the construction and propagation of the functional cDNA. Here, the present report describes the strategic considerations in creating and amplifying a genetically stable full-length infectious JEV cDNA as a bacterial artificial chromosome (BAC) using the following general experimental procedures: viral RNA isolation, cDNA synthesis, cDNA subcloning and modification, assembly of a full-length cDNA, cDNA linearization, in vitro RNA synthesis, and virus recovery. This protocol provides a general methodology applicable to cloning full-length cDNA for a range of positive-strand RNA viruses, particularly those with a genome of >10 kb in length, into a BAC vector, from which infectious RNAs can be transcribed in vitro with a bacteriophage RNA polymerase. 相似文献
10.