全文获取类型
收费全文 | 813篇 |
免费 | 32篇 |
出版年
2022年 | 8篇 |
2021年 | 13篇 |
2020年 | 8篇 |
2019年 | 10篇 |
2018年 | 13篇 |
2017年 | 5篇 |
2016年 | 14篇 |
2015年 | 15篇 |
2014年 | 27篇 |
2013年 | 40篇 |
2012年 | 69篇 |
2011年 | 51篇 |
2010年 | 24篇 |
2009年 | 30篇 |
2008年 | 43篇 |
2007年 | 38篇 |
2006年 | 16篇 |
2005年 | 25篇 |
2004年 | 38篇 |
2003年 | 28篇 |
2002年 | 25篇 |
2001年 | 17篇 |
2000年 | 22篇 |
1999年 | 15篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 10篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 17篇 |
1991年 | 21篇 |
1990年 | 21篇 |
1989年 | 14篇 |
1988年 | 17篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1979年 | 11篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1975年 | 4篇 |
1974年 | 10篇 |
1973年 | 5篇 |
1971年 | 8篇 |
1968年 | 3篇 |
排序方式: 共有845条查询结果,搜索用时 19 毫秒
1.
Integration into the host genome is an essential step in the HIV-1 life cycle. However, the host genome sequence that is favored by HIV-1 during integration has never been documented. Here, we report that CD27, a T cell activation gene, includes a sequence that is a target for in vitro HIV-1 cDNA integration. This sequence has a high affinity for integrase, and the target nucleotides responsible for this higher affinity were identified using a crystal microbalance assay. In experiments involving a segment of the CD27 gene, integration converged in the target nucleotides and flanking sequence DNA, indicating that integration is probably dependent upon the secondary structure of the substrate DNA. Notably, decoy modified CD27 sequence DNAs in which the target nucleotides were replaced suppressed integration when accompanying the original CD27 sequence DNA. Our identified CD27 sequence DNA is useful for investigating the biochemistry of integrase and for in vitro assessment of integrase-binding inhibitors. 相似文献
2.
A new snake-eel,Apterichtus keramanus, is described on the basis of a single 276-mm TL specimen trawled from the coast of Kerama Islands, Okinawa Prefecture, Japan.
The species is unique in the genus in having the posterior nostril opening entirely inside the mouth and a dark band running
from the anteroventral margin of the eye to the upper lip. 相似文献
3.
4.
5.
Midori Hiramatsu Rei Edamatsu Shigeo Suzuki Masakazu Shimada Akitane Mori 《Neurochemical research》1990,15(8):821-825
Inbred mutant El mice are highly susceptible to convulsive seizures upon tossing stimulation. The levels of excitatory (e.g. glutamate and aspartate) and inhibitory amino acids [e.g. -aminobutyrate (GABA)] were examined in discrete regions of stimulated El mice [El(+)] non-stimulated El mice [El(-)] and ddY mice, which do not have convulsive disposition. In comparison with ddY, a general increased levels of aspartate, glutamate, glutamine, and taurine were detected in brain regions of El(-). The levels of GABA and glycine were almost the same in ddY and El(-). Compared to El(+), the levels of aspartate, glutamate, glutamine, and GABA in El(-) were either the same or higher. In the case of taurine and glycine, the levels in El(-) were either the same or lower than El(+). Alanine is special in that El(-) have a higher level than El(+) in hippocampus but lower in cerebellum. Furthermore, while marked changes were registered in several brain regions, none of the amino acids investigated showed any significant differences in the hypothalamus of three different groups of mice. 相似文献
6.
K Yamakawa S Kamiya S Nishida K Yoshimura H Yu D Y Lu S Nakamura 《Microbiology and immunology》1988,32(6):579-587
Soil specimens obtained from several areas of Japan, which are closely located to or facing the Continental land of China, were examined for the distribution of Clostridium botulinum, especially pertaining to types A and B. A total of 266 specimens of Japan, when cultured, showed no type A or B toxicity, although 30 (11.3%), 4 (1.5%), and 10 (3.8%) of the specimens showed C1, C2, and type E toxicities, respectively. On the contrary, types A and/or B toxicities were shown, by the same method, in 14 of 20 specimens of Shinkiang district, China. The highest number of C. botulinum cells found in one gram of soil specimen was 25 for type A and 10 for type B. 相似文献
7.
T Masaki H Umehashi H Miyazaki M Takano K Yamakawa S Nakamura 《Japanese journal of medical science & biology》1988,41(1):27-30
A Clostridium perfringens-like strain was isolated from a case of gas gangrene. The morphological properties and the lecithinase reaction of the isolate were very similar to those of C. perfringens; however, the lecithinase reaction was only slightly suppressed by C. perfringens alpha-antitoxin serum and the organism was identified as Clostridium absonum from its biochemical properties. 相似文献
8.
N Kashiwazaki J Mizuno H Nagashima A Mizuno H Yamakawa J Yamanoi S Ogawa 《Jikken dobutsu》1988,37(2):127-135
Using the halved morulae of mice obtained with microsurgical technique, the following two experiments were performed. 1) Sexing of half-embryos by chromosomal analysis and transfer of the half-embryos after determining the sex of the other monozygotic half. One half of the bisected embryo was cultured in Colcemid solution (0.04 micrograms/ml) to be ensured for chromosomal preparation. More than 50% (152/270) of the blastulated embryos from the halves could be sexed by direct sex chromosome analysis. Thirty-nine of the half-embryos of which the co-twin halves were sexed, were transplanted in to the uterine horns of 18 pseudopregnant mice, and twelve became pregnant. The autopsies of them on Day 18 to 20 of pregnancy, revealed the presence of 16 fetuses. The morphological sex of these fetuses thus obtained coincided completely with the previous judgement based on the chromosomal sexing. 2) Production of chimeras of defined sex composition by aggregating two half-morulae of defined sex. Out of 147 pairs of half-morulae of two different strains (ICR and C3H/He), which were replaced in pairs into empty zona pellucidae, 107 (72.8%) were aggregated successfully and developed in vitro into full expanding blastocysts of typical form. Among the 107 aggregate blastocysts, 31 were sexed for both component embryos by chromosomal analysis on the co-twin half-embryos. When these 31 blastocysts were transferred, 11 living offspring including 4 chimeras were obtained. Transfer of 12 male-male and 5 female-female aggregate blastocysts resulted in 8 males and 1 female, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
9.
Serum and tissue CoQ9 levels were determined in hypothyroid, euthyroid and hyperthyroid rats. A significant negative correlation was demonstrated between serum FT4 or T3 and CoQ9 in rats with various states of thyroid functions. Liver CoQ9 was significantly increased in rats rendered mildly hyperthyroid. There was a significant positive correlation between serum FT4 or T3 and liver CoQ9. While liver CoQ9 did not significantly change in severely hyperthyroid animals, liver mitochondrial CoQ9 showed a significant positive correlation with serum T3. Kidney and heart CoQ9 levels did not significantly change in hyperthyroid rats, but those in hypothyroid rats showed a tendency to increase. It was suggested that the synthesis of CoQ9 was increased in the liver in hyperthyroidism. 相似文献