全文获取类型
收费全文 | 2151篇 |
免费 | 104篇 |
出版年
2023年 | 3篇 |
2022年 | 9篇 |
2021年 | 21篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 32篇 |
2017年 | 20篇 |
2016年 | 44篇 |
2015年 | 79篇 |
2014年 | 76篇 |
2013年 | 124篇 |
2012年 | 146篇 |
2011年 | 152篇 |
2010年 | 93篇 |
2009年 | 95篇 |
2008年 | 159篇 |
2007年 | 149篇 |
2006年 | 132篇 |
2005年 | 149篇 |
2004年 | 136篇 |
2003年 | 142篇 |
2002年 | 125篇 |
2001年 | 22篇 |
2000年 | 16篇 |
1999年 | 27篇 |
1998年 | 29篇 |
1997年 | 28篇 |
1996年 | 24篇 |
1995年 | 32篇 |
1994年 | 11篇 |
1993年 | 19篇 |
1992年 | 22篇 |
1991年 | 12篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1977年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1970年 | 3篇 |
排序方式: 共有2255条查询结果,搜索用时 31 毫秒
51.
Naoto Burioka Miyako Takata Masahiro Endo Masanori Miyata Kenichi Takeda Hiroki Chikumi 《Chronobiology international》2013,30(1):183-189
This study examined whether in vivo exposure to a β2‐adrenoceptor agonist, tulobuterol, induces human Period1 (hPer1) mRNA expression in cells from peripheral whole blood. In one experiment, oral tulobuterol was administered to five healthy volunteers at 22:00 h, while in another, a transdermally tulobuterol patch was applied to the same five subjects at 20:00 h. In each experiment, serum tulobuterol concentrations were measured at four time points, and total RNA was isolated from peripheral blood cells for determinations of hPer1 mRNA expression by real‐time polymerase chain reaction. Both the tulobuterol tablet and the transdermal patch increased hPer1 mRNA expression, suggesting that analyses of human peripheral blood cells could reliably represent peripheral clock gene mRNA expression in vivo. 相似文献
52.
Masanori Honsho Shunsuke Asaoku Keiko Fukumoto Yukio Fujiki 《The Journal of biological chemistry》2013,288(48):34588-34598
Peroxisomal fatty acyl-CoA reductase 1 (Far1) is essential for supplying fatty alcohols required for ether bond formation in ether glycerophospholipid synthesis. The stability of Far1 is regulated by a mechanism that is dependent on cellular plasmalogen levels. However, the membrane topology of Far1 and how Far1 is targeted to membranes remain largely unknown. Here, Far1 is shown to be a peroxisomal tail-anchored protein. The hydrophobic C terminus of Far1 binds to Pex19p, a cytosolic receptor harboring a C-terminal CAAX motif, which is responsible for the targeting of Far1 to peroxisomes. Far1, but not Far2, was preferentially degraded in response to the cellular level of plasmalogens. Experiments in which regions of Far1 or Far2 were replaced with the corresponding region of the other protein showed that the region flanking the transmembrane domain of Far1 is required for plasmalogen-dependent modulation of Far1 stability. Expression of Far1 increased plasmalogen synthesis in wild-type Chinese hamster ovary cells, strongly suggesting that Far1 is a rate-limiting enzyme for plasmalogen synthesis. 相似文献
53.
Masanori Terai Naotaka Izumiyama-Shimomura Junko Aida Naoshi Ishikawa Mie Kuroiwa Steven S.S. Poon Tomio Arai Masashi Toyoda Hidenori Akutsu Akihiro Umezawa Ken-ichi Nakamura Kaiyo Takubo 《Tissue & cell》2013,45(6):407-413
Here we attempted to clarify telomere metabolism in parental cells and their derived clonal human induced pluripotent stem cells (iPSCs) at different passages using quantitative fluorescence in situ hybridization (Q-FISH). Our methodology involved estimation of the individual telomere lengths of chromosomal arms in individual cells within each clone in relation to telomere fluorescence units (TFUs) determined by Q-FISH. TFUs were very variable within the same metaphase spread and within the same cell. TFUs of the established iPSCs derived from human amnion (hAM933 iPSCs), expressed as mean values of the median TFUs of 20 karyotypes, were significantly longer than those of the parental cells, although the telomere extension rates varied quite significantly among the clones. Twenty metaphase spreads from hAM933 iPSCs demonstrated no chromosomal instability. The iPSCs established from fetal lung fibroblasts (MRC-5) did not exhibit telomere shortening and chromosomal instability as the number of passages increased. However, the telomeres of other iPSCs derived from MRC-5 became shorter as the number of passages increased, and one (5%) of 20 metaphase spreads showed chromosomal abnormalities including X trisomy at an early stage and all 20 showed abnormalities including X and 12 trisomies at the late stage. 相似文献
54.
Jun-ichi Kanatani Junko Isobe Keiko Kimata Tomoko Shima Miwako Shimizu Fumiaki Kura Tetsutaro Sata Masanori Watahiki 《Applied and environmental microbiology》2013,79(13):3959-3966
We investigated the prevalence of Legionella species isolated from puddles on asphalt roads. In addition, we carried out sequence-based typing (SBT) analysis on the genetic relationship between L. pneumophila serogroup 1 (SG 1) isolates from puddles and from stock strains previously obtained from sputum specimens and public baths. Sixty-nine water samples were collected from puddles on roads at 6 fixed locations. Legionella species were detected in 33 samples (47.8%) regardless of season. Among the 325 isolates from puddles, strains of L. pneumophila SG 1, a major causative agent of Legionnaires'' disease, were the most frequently isolated (n = 62, 19.1%). Sixty-two isolates of L. pneumophila SG 1 from puddles were classified into 36 sequence types (STs) by SBT. ST120 and ST48 were identified as major STs. Environmental ST120 strains from puddles were found for the first time in this study. Among the 14 STs of the clinical isolates (n = 19), 4 STs (n = 6, 31.6%), including ST120, were also detected in isolates from puddles on roads, and the sources of infection in these cases remained unclear. The lag-1 gene, a tentative marker for clinical isolates, was prevalent in puddle isolates (61.3%). Our findings suggest that puddles on asphalt roads serve as potential reservoirs for L. pneumophila in the environment. 相似文献
55.
Takashi Kitayama Kanako Yasuda Takeharu Kihara Michiho Ito Hiromi Fukumoto Masanori Morimoto 《Applied Entomology and Zoology》2013,48(4):455-459
Piper ribersoides Wall. (Piperaceae), which is called “Khua Sa khan” in the local language, is mainly grown in Laos. This plant is used as a food in Laos, but no report on its metabolites exists. Crushed stems were immersed in methanol. The ethyl acetate fraction showed potential insect antifeedant activity for Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), and some of the active compounds were piperine analogs. Piperine and its geometrical isomer independently showed potent antifeedant activities, and piperine was presumably the main active compound in the methanol extract. Interestingly, we discovered that the antifeedant activity was reduced when they were mixed (50:50). 相似文献
56.
57.
Masanori Asada Kazuhiro Morimoto Kazuhiro Nakanishi Ryuichi Matsuno Atsuo Tanaka Akira Kimura 《Bioscience, biotechnology, and biochemistry》2013,77(8):1773-1774
Arthrobacter simplex was screened as an α-keto-δ-guanidinovalerate (ketoarginine) assimilating organism. A characteristic feature was its growth on ketoarginine as a carbon source; it began to grow after an extremely long lag. Its growth was stimulated by addition of 0.02% yeast extract to the medium.The results indicated the transamination of arginine-α-ketoglutarate (α-KGA) and the hydrolyzing reaction of ketoarginine into α-keto-δ-aminovalerate and urea. Two intermediates, ketoarginine and α-keto-δ-aminovalerate, were isolated and identified by various procedures. Coupling of the two reactions was demonstrated in cell-free extracts of arginine-grown cells; ketoarginine formed from arginine by transamination with α-KGA was hydrolyzed directly to α-keto-δ-aminovalerate and urea. The metabolic routes of arginine in microorganisms were discussed. 相似文献
58.
Tomohisa Nagasaki Masanori Sugita Hideaki Fukawa Hsin-Tung Lin 《Bioscience, biotechnology, and biochemistry》2013,77(2):363-369
Taxonomical investigation was performed on the bacterium, strain NB 320 isolated from soil, and it was identified as Enterobacter cloacae. This bacterium produced the enzyme which catalyzed the transamination reaction between 3,4-dihydroxyphenyl pyruvate and an amino acid to form l-Dopa.The optimum culture conditions for the enzyme production were studied along with the characteristics of the enzyme. The enzyme of the strain was different in some properties from that of Alcaligenes faecalis IAM 1015 which had been already studied. The former utilized glutamate as an amino donor best among the amino acids tested for transamination and was induced by the addition of glutamine and asparagine. Intact cells of the strain did not catalyze the reaction unless they were treated with sonication or with a detergent. 相似文献
59.
Tomohisa Nagasaki Masanori Sugita Hideaki Fukawa 《Bioscience, biotechnology, and biochemistry》2013,77(7):1701-1706
Some enzymatic properties were examined on the transaminase (DOPA transaminase) which catalyzes the reaction between 3,4-dihydroxy phenyl pyruvate (DOPP) and certain amino acids to form 3,4-dihydroxyphenyl-L-alanine (DOPA). The cell-free extract from Alcaligenes faecalis IAM 1015 was used as the DOPA transaminase. L-Aspartate, L-glutamate, and L-phenylalanine were utilized efficiently as amino donor. The occurrence of three kinds of transaminase—aspartate-DOPP transaminase (ADT), glutamate-DOPP transaminase (GDT), and phenylalanine-DOPP transaminase (PDT)—was postulated.The pH optima of these enzymes were observed in the alkaline pH range. The enzymes were unstable in the acidic range and inactivated above 60°C. Ca2+, Mg2+, and Mn2+ protected PDT from heat denaturation. Fe2+, Cu2+, and Al3+ remarkably inhibited the enzyme reaction. 相似文献
60.
Tomohiro Teraminami Atsushi Nakashima Mao Ominami Masanori Yamamoto Zhang Guo Sheng Ken Yoshikawa 《Landscape and Ecological Engineering》2013,9(2):249-257
Salix cheilophila Schneid. is a naturally occurring Salix species in Mu Us Sandy Land, Inner Mongolia, China. We focused on the morphological adaptability of S. cheilophila to sand dune burial. For morphological measurements, 32 S. cheilophila seedlings were removed from a community which was in the process of being buried by a shifting sand dune. Each seedling collected included the entire root system. We measured the number, length, and biomass of the adventitious roots, primary lateral roots, and taproot, and compared the morphological characteristics of the root system, including adventitious roots, for seedlings buried to various levels in the sand. The growth range of adventitious roots increased as the length of the buried portion of the main shoot increased. In addition, the total dry weight of all current-year shoots tended to increase gradually with increasing total dry weight of the adventitious roots. These results suggest that S. cheilophila tends to make use of the sedimentary sand layer that accompanies shifting sand dunes. However, there was no correlation between biomass or number of adventitious roots and the length of the buried part of the main shoot. Thus, S. cheilophila does not grow adventitious roots proportional to the buried part. These morphological characteristics of the root system, including the adventitious roots, may indicate that S. cheilophila has poor morphological adaptability to sand dune burial. 相似文献