全文获取类型
收费全文 | 1706篇 |
免费 | 87篇 |
国内免费 | 5篇 |
专业分类
1798篇 |
出版年
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 22篇 |
2019年 | 13篇 |
2018年 | 14篇 |
2017年 | 15篇 |
2016年 | 33篇 |
2015年 | 38篇 |
2014年 | 47篇 |
2013年 | 166篇 |
2012年 | 108篇 |
2011年 | 118篇 |
2010年 | 69篇 |
2009年 | 72篇 |
2008年 | 112篇 |
2007年 | 107篇 |
2006年 | 109篇 |
2005年 | 119篇 |
2004年 | 103篇 |
2003年 | 92篇 |
2002年 | 88篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 19篇 |
1998年 | 14篇 |
1997年 | 24篇 |
1996年 | 15篇 |
1995年 | 21篇 |
1994年 | 20篇 |
1993年 | 14篇 |
1992年 | 15篇 |
1991年 | 11篇 |
1990年 | 10篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 20篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 5篇 |
1978年 | 9篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 6篇 |
排序方式: 共有1798条查询结果,搜索用时 0 毫秒
61.
Maejima H Kinoshita E Yuki T Yakehiro M Seyama I Yamaoka K 《Biochemical and biophysical research communications》2002,295(2):452-457
We located a novel binding site for grayanotoxin on the cytoplasmic linkers of voltage-dependent cardiac (rH1) or skeletal-muscle (mu 1) Na(+) channel isoforms (segments S4-S5 in domains D1 and D4), using the alanine scanning substitution method. GTX-modification of Na(+) channels, transiently expressed in HEK 293 cells, was evaluated under whole-cell voltage clamp, from the ratio of maximum chord conductance for modified and unmodified Na(+) channels. In mu 1, mutations K237A, L243A, S246A, K248A, K249A, L250A, S251A, or T1463A, caused a moderate, but statistically significant decrease in this ratio. On making corresponding mutations in rH1, only L244A dramatically reduced the ratio. Because in mu 1, the serine at position 251 is the only heterologous residue with respect to rH1 (Ala-252), we made a double mutant L243A&S251A to match the sequence of mu 1 and rH1 in S4-S5 linkers of both domains. This double mutation resulted in a significant decrease in the ratio, to the same extent as L244A substitution in rH1 did, indicating that the site at Leu-244 in rH1 or at Leu-243 in mu 1 is a novel one, exhibiting a synergistic effect of grayanotoxin. 相似文献
62.
We searched for a human chromosome that would restore the cholesterol metabolism in 3T3 cell lines (SPM-3T3) derived from homozygous sphingomyelinosis mice (spm/spm). Mouse A9 cells containing a single copy of pSV2neo-tagged chromosomes 9, 11, or 18 derived from normal human fibroblasts served as donor cells for transfer of human chromosomes. Purified A9 microcells were fused with SPM-3T3 cells, and the microcell hybrids were selected in medium containing G418 antibiotics. The microcell hybrids that contained human chromosomes 9, 11, or 18 in a majority of cells were examined. The accumulation of intracellular cholesterol in the microcell hybrids containing a chromosome 18 decreased markedly, whereas in the microcell hybrids containing either chromosomes 9 or 11 it was similar to that in SPM3T3 cells. The SPM-3T3 cells with an intact chromosome 18 were further passaged and subcloned. Clones which again accumulated intracellular cholesterol had concurrently lost the introduced chromosome 18. The abnormal accumulation was associated with a decrement in the esterification of exogenous cholesterol. These findings suggest that the gene responsible for the abnormal cholesterol metabolism in the spm/spm mice can be restored by a hu man chromosome 18. The gene was tentatively mapped on 18pter18p11.3 or 18q21.3qter that was lost during subcloning, thereby resulting in reaccumulation of the intracellular cholesterol. 相似文献
63.
Asterorhombus annulatus was long synonymized with A. intermedius. Twenty-nine specimens from the Coral Sea revealed that the former is clearly separable from the latter in having a short
first dorsal fin ray, slender gill rakers with spinules, distinctly shorter blind-side pelvic fin base, an absence of conspicuous
black spots on the ocular side of the body, greater eye diameter and greater interorbital width, and somewhat higher ranges
of upper jaw lengths. A. annulatus is redescribed as a valid species.
Received: March 4, 2000 / Revised: September 13, 2000 / Accepted: January 12, 2001 相似文献
64.
Hideki Sezutsu Eiji Nitasaka Tsuneyuki Yamazaki 《Molecular & general genetics : MGG》1995,249(2):168-178
LINE-like retrotransposons, the so-called I elements, control the system of I-R (inducer-reactive) hybrid dysgenesis in Drosophila melanogaster. I elements are present in many Drosophila species. It has been suggested that active, complete I elements, located at different sites on the chromosomes, invaded natural populations of D. melanogaster recently (1920–1970). But old strains lacking active I elements have only defective I elements located in the chromocenter. We have cloned I elements from D. melanogaster and the melanogaster subgroup. In D. melanogaster, the nucleotide sequences of chromocentral I elements differed from those on chromosome arms by as much as 7%. All the I elements of D. mauritiana and D. sechellia are more closely related to the chromosomal I elements of D. melanogaster than to the chromocentral I elements in any species. No sequence difference was observed in the surveyed region between two chromosomal I elements isolated from D. melanogaster and one from D. simulans. These findings strongly support the idea that the defective chromocentral I elements of D. melanogaster originated before the species diverged and the chromosomal I elements were eliminated. The chromosomal I elements reinvaded natural populations of D. melanogaster recently, and were possibly introduced from D. simulans by horizontal transmission. 相似文献
65.
Nakajima Y Ito K Toshima T Egawa T Zheng H Oyama H Wu YF Takahashi E Kyono K Yoshimoto T 《Journal of bacteriology》2008,190(23):7819-7829
The crystal structure of dipeptidyl aminopeptidase IV from Stenotrophomonas maltophilia was determined at 2.8-A resolution by the multiple isomorphous replacement method, using platinum and selenomethionine derivatives. The crystals belong to space group P4(3)2(1)2, with unit cell parameters a = b = 105.9 A and c = 161.9 A. Dipeptidyl aminopeptidase IV is a homodimer, and the subunit structure is composed of two domains, namely, N-terminal beta-propeller and C-terminal catalytic domains. At the active site, a hydrophobic pocket to accommodate a proline residue of the substrate is conserved as well as those of mammalian enzymes. Stenotrophomonas dipeptidyl aminopeptidase IV exhibited activity toward a substrate containing a 4-hydroxyproline residue at the second position from the N terminus. In the Stenotrophomonas enzyme, one of the residues composing the hydrophobic pocket at the active site is changed to Asn611 from the corresponding residue of Tyr631 in the porcine enzyme, which showed very low activity against the substrate containing 4-hydroxyproline. The N611Y mutant enzyme was generated by site-directed mutagenesis. The activity of this mutant enzyme toward a substrate containing 4-hydroxyproline decreased to 30.6% of that of the wild-type enzyme. Accordingly, it was considered that Asn611 would be one of the major factors involved in the recognition of substrates containing 4-hydroxyproline. 相似文献
66.
67.
68.
69.
Yasuhito Hamaguchi Manabu Fujimoto Takashi Matsushita Kenzo Kaji Kazuhiro Komura Minoru Hasegawa Masanari Kodera Eiji Muroi Keita Fujikawa Mariko Seishima Hidehiro Yamada Ryo Yamada Shinichi Sato Kazuhiko Takehara Masataka Kuwana 《PloS one》2013,8(4)
Objective
To identify similarities and differences in the clinical features of adult Japanese patients with individual anti-aminoacyl-tRNA synthetase antibodies (anti-ARS Abs).Methods
This was a retrospective analysis of 166 adult Japanese patients with anti-ARS Abs detected by immunoprecipitation assays. These patients had visited Kanazawa University Hospital or collaborating medical centers from 2003 to 2009.Results
Anti-ARS Ab specificity included anti-Jo-1 (36%), anti-EJ (23%), anti-PL-7 (18%), anti-PL-12 (11%), anti-KS (8%), and anti-OJ (5%). These anti-ARS Abs were mutually exclusive, except for one serum Ab that had both anti-PL-7 and PL-12 reactivity. Myositis was closely associated with anti-Jo-1, anti-EJ, and anti-PL-7, while interstitial lung disease (ILD) was correlated with all 6 anti-ARS Abs. Dermatomyositis (DM)-specific skin manifestations (heliotrope rash and Gottron’s sign) were frequently observed in patients with anti-Jo-1, anti-EJ, anti-PL-7, and anti-PL-12. Therefore, most clinical diagnoses were polymyositis or DM for anti-Jo-1, anti-EJ, and anti-PL-7; clinically amyopathic DM or ILD for anti-PL-12; and ILD for anti-KS and anti-OJ. Patients with anti-Jo-1, anti-EJ, and anti-PL-7 developed myositis later if they had ILD alone at the time of disease onset, and most patients with anti-ARS Abs eventually developed ILD if they did not have ILD at disease onset.Conclusion
Patients with anti-ARS Abs are relatively homogeneous. However, the distribution and timing of myositis, ILD, and rashes differ among patients with individual anti-ARS Abs. Thus, identification of individual anti-ARS Abs is beneficial to define this rather homogeneous subset and to predict clinical outcomes within the “anti-synthetase syndrome.” 相似文献70.
Hiroki Tawaratsumida Takao Setoguchi Yoshiya Arishima Hideo Ohtsubo Masaki Akimoto Yasuhiro Ishidou Satoshi Nagano Eiji Taketomi Nobuhiko Sunahara Setsuro Komiya 《BMC research notes》2017,10(1):765