全文获取类型
收费全文 | 543271篇 |
免费 | 48815篇 |
国内免费 | 1048篇 |
专业分类
593134篇 |
出版年
2018年 | 16953篇 |
2017年 | 15822篇 |
2016年 | 13644篇 |
2015年 | 7832篇 |
2014年 | 8769篇 |
2013年 | 11979篇 |
2012年 | 18221篇 |
2011年 | 28338篇 |
2010年 | 22983篇 |
2009年 | 18752篇 |
2008年 | 23976篇 |
2007年 | 26596篇 |
2006年 | 12693篇 |
2005年 | 13167篇 |
2004年 | 13156篇 |
2003年 | 12707篇 |
2002年 | 12223篇 |
2001年 | 17824篇 |
2000年 | 17802篇 |
1999年 | 14088篇 |
1998年 | 5226篇 |
1997年 | 5439篇 |
1996年 | 5066篇 |
1995年 | 4753篇 |
1994年 | 4613篇 |
1993年 | 4707篇 |
1992年 | 11792篇 |
1991年 | 11709篇 |
1990年 | 11435篇 |
1989年 | 11025篇 |
1988年 | 10595篇 |
1987年 | 10181篇 |
1986年 | 9428篇 |
1985年 | 9340篇 |
1984年 | 7858篇 |
1983年 | 6796篇 |
1982年 | 5269篇 |
1981年 | 4695篇 |
1980年 | 4535篇 |
1979年 | 7489篇 |
1978年 | 5918篇 |
1977年 | 5465篇 |
1976年 | 5269篇 |
1975年 | 5648篇 |
1974年 | 6338篇 |
1973年 | 6214篇 |
1972年 | 6387篇 |
1971年 | 5820篇 |
1970年 | 4653篇 |
1969年 | 4597篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
995.
P Salgame A S Varadhachary L L Primiano J E Fincke S Muller M Monestier 《Nucleic acids research》1997,25(3):680-681
We describe a simple and convenient enzyme-linked immunosorbent assay (ELISA) for the detection of apoptosis in tissue culture. An early event in apoptosis is DNA fragmentation followed by release of nucleosomes into the cytoplasm. Our sandwich assay uses a pair of monoclonal antibodies specific for two nucleosomal epitopes to capture and detect cytoplasmic nucleosomes onto the ELISA plate. Our assay is about 500 times more sensitive than the detection of apoptotic DNA ladder by agarose electrophoresis and is especially suited for the testing of large numbers of samples. 相似文献
996.
E. V. Levites 《Russian Journal of Genetics》2012,48(11):1158-1161
Variability was revealed in the isozyme spectra in the seed progeny from crosses of two beet plants homozygous for contrasting alleles of marker enzyme loci. 相似文献
997.
The optimum temperature for multiplication of legionella strains in culture media is around 37°C. The effect of high temperatures on the growth of strains isolated from various environments is poorly known. We studied the growth (cell multiplication, respiration) of clinical and environmental Legionella pneumophila strains in liquid media at intervals of 0.5°C in the temperature range from 41.6 to 51.6°C using a temperature gradient incubator. Cell multiplication and CO2 production decreased markedly with all the strains at temperatures above 44–45°C. CO2 continued to be produced up to 51.6C even if cell multiplication generally stopped at around 48.4–50.0C. Thus, legionella retained its metabolic activity beyond the maximum temperature for cell multiplication. The CO2 production per bacterial cell (metabolic quotient, qCO2 ) increased with increasing temperature up to 45°C, whereafter it decreased, the turning point being almost at the same at which the rate of cell multiplication decreased. The difference in qCO2 between the strains may reflect their different physiological capacities for tolerating high temperatures. 相似文献
998.
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
999.
J. M. SORIANO S. PECCHIOLI C. ROMERO S. VILANOVA G. LLCER E. GIORDANI M. L. BADENES 《Molecular ecology resources》2006,6(2):368-370
The oriental persimmon (Diospyros kaki Lf) is believed to have originated in China with subsequent introduction into Japan and Korea in ancient times. The species was then brought to Europe, Brazil and the USA from Japan in the 19th century. Recent studies highlighted the poor state of identification of cultivars in these countries due to incorrect labelling and presence of synonyms among local varieties. Thus, molecular marker characterization of germplasm resources is of great value for genetic resource preservation and plant breeding of persimmon. Therefore, to identify accessions for further plant breeding and germplasm management, 37 microsatellite loci were developed from a CT/AG‐enriched persimmon genomic library. 相似文献
1000.
Pawan K. Dhar 《Journal of biosciences》2007,32(1):1005-1008
Systems biology is an approach to explain the behaviour of a system in relation to its individual components. Synthetic biology uses key hierarchical and modular concepts of systems biology to engineer novel biological systems. In my opinion the next step in biology is to use molecule-to-phenotype data using these approaches and integrate them in the form a periodic table. A periodic table in biology would provide chassis to classify, systematize and compare diversity of component properties vis-a-vis system behaviour. Using periodic table it could be possible to compute higher-level interactions from component properties. This paper examines the concept of building a bio-periodic table using protein fold as the fundamental unit. 相似文献