全文获取类型
收费全文 | 1697篇 |
免费 | 65篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 7篇 |
2019年 | 12篇 |
2018年 | 16篇 |
2017年 | 15篇 |
2016年 | 21篇 |
2015年 | 44篇 |
2014年 | 64篇 |
2013年 | 116篇 |
2012年 | 86篇 |
2011年 | 89篇 |
2010年 | 57篇 |
2009年 | 70篇 |
2008年 | 112篇 |
2007年 | 91篇 |
2006年 | 117篇 |
2005年 | 96篇 |
2004年 | 106篇 |
2003年 | 123篇 |
2002年 | 139篇 |
2001年 | 19篇 |
2000年 | 18篇 |
1999年 | 36篇 |
1998年 | 35篇 |
1997年 | 35篇 |
1996年 | 18篇 |
1995年 | 22篇 |
1994年 | 25篇 |
1993年 | 24篇 |
1992年 | 13篇 |
1991年 | 18篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 13篇 |
1983年 | 3篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1964年 | 2篇 |
排序方式: 共有1762条查询结果,搜索用时 15 毫秒
981.
982.
Toru Kubota Noriyuki Yonekura Yasushi Hariya Emiko Isogai Hiroshi Isogai Ken-ichi Amano Nobuhiro Fujii 《FEMS microbiology letters》1998,158(2):215-221
The cluster of genes encoding the botulinum progenitor toxin and the upstream region including p21 and p47 were divided into three different gene arrangements (class I–III). To determine the gene similarity of the type E neurotoxin (BoNT/E) complex to other types, the gene organization in the upstream region of the nontoxic-nonhemagglutinin gene (ntnh) was investigated in chromosomal DNA from Clostridium botulinum type E strain Iwanai and C. butyricum strain BL6340. The gene cluster of type E progenitor toxin (Iwanai and BL6340) was similar to those of type F and type A (from infant botulism in Japan), but not to those of types A, B, and C. Though genes for the hemagglutinin component and P21 were not discovered, genes encoding P47, NTNH, and BoNT were found in type E strain Iwanai and C. butyricum strain BL6340. However, the genes of ORF-X1 (435 bp) and ORF-X2 (partially sequenced) were present just upstream of that of P47. The orientation of these genes was in inverted direction to that of p47. The gene cluster of type E progenitor toxin (Iwanai and BL6340) is, therefore, a specific arrangement (class IV) among the genes encoding components of the BoNT complex. 相似文献
983.
984.
Ken-ichi Hosoya Michiko Sugawara Hiroshi Asaba Tetsuya Terasaki 《Journal of neurochemistry》1999,73(3):1206-1211
The brain efflux index method has been used to clarify the mechanism of efflux transport of acidic amino acids such as L-aspartic acid (L-Asp), L-glutamic acid (L-Glu), and D-aspartic acid (D-Asp) across the blood-brain barrier (BBB). About 85% of L-[3H]Asp and 40% of L-[3H]Glu was eliminated from the ipsilateral cerebrum within, respectively, 10 and 20 min of microinjection into the brain. The efflux rate constant of L-[3H]Asp and L-[3H]Glu was 0.207 and 0.0346 min(-1), respectively. However, D-[3H]Asp was not eliminated from brain over a 20-min period. The efflux of L-[3H]Asp and L-[3H]Glu was inhibited in the presence of excess unlabeled L-Asp and L-Glu, whereas D-Asp did not inhibit either form of efflux transport. Aspartic acid efflux across the BBB appears to be stereospecific. Using a combination of TLC and the bioimaging analysis, attempts were made to detect the metabolites of L-[3H]Asp and L-[3H]Glu in the ipsilateral cerebrum and jugular vein plasma following a microinjection into parietal cortex, area 2. Significant amounts of intact L-[3H]Asp and L-[3H]Glu were found in all samples examined, including jugular vein plasma, providing direct evidence that at least a part of the L-Asp and L-Glu in the brain interstitial fluid is transported across the BBB in the intact form. To compare the transport of acidic amino acids using brain parenchymal cells, brain slice uptake studies were performed. Although the slice-to-medium ratio of D-[3H]Asp was the highest, followed by L-[3H]Glu and L-[3H]Asp, the initial uptake rate did not differ for both L-[3H]Asp and D-[3H]Asp, suggesting that the uptake of aspartic acid in brain parenchymal cells is not stereospecific. These results provide evidence that the BBB may act as an efflux pump for L-Asp and L-Glu to reduce the brain interstitial fluid concentration and act as a static wall for D-Asp. 相似文献
985.
A Fission Yeast Gene, him1+/dfp1+, Encoding a Regulatory Subunit for Hsk1 Kinase, Plays Essential Roles in S-Phase Initiation as Well as in S-Phase Checkpoint Control and Recovery from DNA Damage 下载免费PDF全文
986.
987.
Takashi Iwasa Terukazu Takano Ken-ichi Hara Tosio Kamei 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1999,734(2):1728
A liquid chromatography–electrospray ionization tandem mass spectrometric method was developed for the simultaneous determination of losartan and its major active metabolite, EXP-3174, in human plasma. The two analytes and the internal standard (DuP-167) were extracted from plasma under acidic conditions by using solid-phase extraction cartridges containing a sorbent of copolymer, poly(divinylbenzene-co-N-vinylpyrrolidone). The analytes were separated by LC equipped with a reversed-phase C18 column, and introduced into the mass spectrometer via the electrospray ion source with pneumatically-assisted nebulization. For LC–MS–MS samples, an isocratic mobile phase consisting of [0.1% triethylamine–0.1% acetic acid (pH 7.1)]–acetonitorile (65:35, v/v) was used, and the assay was monitored for the negative fragment ions of the analytes. The method demonstrated linearity from 1 to 1000 ng/ml for both losartan and EXP-3174. The limit of quantification for both compounds in plasma was 1 ng/ml. This assay method may be useful for the measurement of levels of the two compounds in clinical studies of losartan. 相似文献
988.
989.
Kohei Kawakami Hiroyuki Matsuo Naoyo Kajitani Takaya Yamada Ken-ichi Matsumoto 《Experimental Animals》2022,71(2):150
Housing conditions can affect the well-being of laboratory animals and thereby affect the outcomes of experiments. The appropriate environment is essential for the expression of natural behavior in animals. Here, we compared survival rates in four inbred mouse strains maintained under three different environmental conditions. Three mouse strains (C57BL/6J, C3H/HeN, and DBA/2J) housed under environmental enrichment (EE) conditions showed improved survival; however, EE did not alter the survival rate of the fourth strain, BALB/c. None of the strains showed significant differences in body weights or plasma corticosterone levels in the three environmental conditions. For BALB/c mice, the rates of debility were higher in the EE group. Interestingly, for C57BL/6J and C3H/HeN mice, the incidence of animals with alopecia was significantly lower in the EE groups than in the control group. It is possible that the enriched environment provided greater opportunities for sheltering in a secure location in which to avoid interactions with other mice. The cloth mat flooring used for the EE group was bitten and chewed by the mice. Our findings suggest that depending on the mouse strains different responses to EE are caused with regard to health and survival rates. The results of this study provide basic data for further studies on EE. 相似文献