全文获取类型
收费全文 | 1272篇 |
免费 | 79篇 |
国内免费 | 1篇 |
出版年
2022年 | 12篇 |
2021年 | 11篇 |
2019年 | 5篇 |
2017年 | 10篇 |
2016年 | 16篇 |
2015年 | 22篇 |
2014年 | 22篇 |
2013年 | 62篇 |
2012年 | 39篇 |
2011年 | 40篇 |
2010年 | 22篇 |
2009年 | 30篇 |
2008年 | 56篇 |
2007年 | 63篇 |
2006年 | 58篇 |
2005年 | 66篇 |
2004年 | 72篇 |
2003年 | 54篇 |
2002年 | 65篇 |
2001年 | 58篇 |
2000年 | 46篇 |
1999年 | 48篇 |
1998年 | 14篇 |
1997年 | 17篇 |
1996年 | 23篇 |
1995年 | 18篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 29篇 |
1991年 | 28篇 |
1990年 | 36篇 |
1989年 | 23篇 |
1988年 | 36篇 |
1987年 | 20篇 |
1986年 | 19篇 |
1985年 | 24篇 |
1984年 | 13篇 |
1983年 | 23篇 |
1982年 | 21篇 |
1981年 | 16篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 12篇 |
1975年 | 9篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 7篇 |
1967年 | 5篇 |
1966年 | 7篇 |
排序方式: 共有1352条查询结果,搜索用时 15 毫秒
71.
72.
Yoshinobu Katoh Tadao Hasegawa Takao Suzuki Taro Fujii 《Bioscience, biotechnology, and biochemistry》2013,77(8):2185-2190
During differentiation after auxin withdrawal, the change in the ethylene production of Hiproly barley callus paralleled the change in 1-aminocyclopropane-1-carboxylic acid (ACC) content. The levels of ACC and ethylene production decreased rapidly, and then increased in Hiproly barley callus.Aminooxyacetic acid (AOA) prevented the ACC and ethylene production of the callus. Moreover, aminoisobutyric acid (AIB) also inhibited the ethylene production, but did not prevent the ACC synthesis of the callus. On the other hand, methylglyoxal-bis(guanylhydrazone) (MGBG) greatly enhanced the ACC and ethylene production. Formation of adventitious roots in Hiproly barley callus was enhanced by the cultivation in the medium containing AIB or AOA. However, differentiation of the callus was strongly inhibited by MGBG.Thus, prevention of ethylene production may be significant for differentiation of Hiproly barley callus. 相似文献
73.
Thienodolin, a new plant growth-regulating substance, was isolated from the fermentation broth of a streptomycete strain identified as Streptomyces albogriseolus.The active principle was extracted with ethyl acetate and purified by silica gel column chromatography and preparative HPLC. The substance showed growth promoting activity with 1.2 × 10?6–1.2 × 10?5 M treatment to rice seedlings, and inhibitory activity with 4.0 × 10?5 M treatment. 相似文献
74.
Surface substances were isolated by sonication from the germinated spores of various strains of Ceratocystis fimbriata and characterized in relation to host-parasite specificity. The substances from the sweet potato strain, compatible with sweet potato, potently inhibited the spore agglutination of various strains by spore-agglutinating factor from sweet potato roots, while the substances from incompatible strains, that is, coffee, taro, and almond strains, weakly inhibited this agglutination. The substances from the sweet potato strain increased ethylene production from sweet potato roots infected by all strains tested, sweet potato, coffee, taro, and almond strains, which was possibly an index of pathogenicity. On the other hand, the substances from incompatible strains, coffee, taro, and almond strains, suppressed the ethylene production from the tissue infected by all four strains except the substances from almond strains on almond strain. Heat and trypsin treatments inactivated the spore agglutination inhibitory activity of the surface substances. Coincidently, these treatments extinguished the effect of the surface substances on pathogenicity of C. fimbriata on sweet potato roots. 相似文献
75.
Hisashi Ashida Kana Tanigawa Masashi Kiyohara Toshihiko Katoh Takane Katayama 《Bioscience, biotechnology, and biochemistry》2013,77(11):2030-2039
ABSTRACTSialidases catalyze the removal of terminal sialic acid from various complex carbohydrates. In the gastrointestinal tract, sialic acid is commonly found in the sugar chain of mucin, and many enteric commensals use mucin as a nutrient source. We previously identified two different sialidase genes in Bifidobacterium bifidum, and one was cloned and expressed as an extracellular protein designated as exo-α-sialidase SiaBb2. The other exo-α-sialidase gene (siabb1) from the same bifidobacterium encodes an extracellular protein (SiaBb1) consisting of 1795 amino acids with a molecular mass of 189 kDa. SiaBb1 possesses a catalytic domain that classifies this enzyme as a glycoside hydrolase family 33 member. SiaBb1 preferentially hydrolyzes α2,3-linked sialic acid over α2,6-linked sialic acid from sialoglycan, which is the same as SiaBb2. However, SiaBb1 has an SGNH hydrolase domain with sialate-O-acetylesterase activity and an N-terminal signal sequence and C-terminal transmembrane region. SiaBb1 is the first bifunctional sialidase identified with esterase activity.Abbreviations: GalNAc: N-acetyl-D-galactosamine; Fuc: L-fucose; Gal: D-galactose 相似文献
76.
Naoto Hirose Atsushi Shimazu Mineo Watanabe Kotaro Tanimoto Souichi Koyota Toshihiro Sugiyama Takashi Uchida Kazuo Tanne 《PloS one》2013,8(1)
Tooth root formation begins after the completion of crown morphogenesis. At the end edge of the tooth crown, inner and outer enamel epithelia form Hertwig’s epithelial root sheath (HERS). HERS extends along with dental follicular tissue for root formation. Ameloblastin (AMBN) is an enamel matrix protein secreted by ameloblasts and HERS derived cells. A number of enamel proteins are eliminated in root formation, except for AMBN. AMBN may be related to tooth root formation; however, its role in this process remains unclear. In this study, we found AMBN in the basal portion of HERS of lower first molar in mice, but not at the tip. We designed and synthesized small interfering RNA (siRNA) targeting AMBN based on the mouse sequence. When AMBN siRNA was injected into a prospective mandibular first molar of postnatal day 10 mice, the root became shorter 10 days later. Furthermore, HERS in these mice revealed a multilayered appearance and 5-bromo-2′-deoxyuridine (BrdU) positive cells increased in the outer layers. In vitro experiments, when cells were compared with and without transiently expressing AMBN mRNA, expression of growth suppressor genes such as p21Cip1 and p27Kip1 was enhanced without AMBN and BrdU incorporation increased. Thus, AMBN may regulate differentiation state of HERS derived cells. Moreover, our results suggest that the expression of AMBN in HERS functions as a trigger for normal root formation. 相似文献
77.
Naoko Minatani Mina Waraya Keishi Yamashita Mariko Kikuchi Hideki Ushiku Ken Kojo Akira Ema Hiroshi Nishimiya Yoshimasa Kosaka Hiroshi Katoh Norihiko Sengoku Hirokazu Tanino David Sidransky Masahiko Watanabe 《PloS one》2016,11(1)
Using pharmacological unmasking microarray, we identified promoter DNA methylation of cysteine dioxygenase 1 (CDO1) gene in human cancer. In this study, we assessed the clinicopathological significance of CDO1 methylation in primary breast cancer (BC) with no prior chemotherapy. The CDO1 DNA methylation was quantified by TaqMan methylation specific PCR (Q-MSP) in 7 BC cell lines and 172 primary BC patients with no prior chemotherapy. Promoter DNA of the CDO1 gene was hypermethylated in 6 BC cell lines except SK-BR3, and CDO1 gene expression was all silenced at mRNA level in the 7 BC cell lines. Quantification of CDO1 methylation was developed using Q-MSP, and assessed in primary BC. Among the clinicopathologic factors, CDO1 methylation level was not statistically significantly associated with any prognostic factors. The log-rank plot analysis elucidated that the higher methylation the tumors harbored, the poorer prognosis the patients exhibited. Using the median value of 58.0 as a cut-off one, disease specific survival in BC patients with CDO1 hypermethylation showed significantly poorer prognosis than those with hypomethylation (p = 0.004). Multivariate Cox proportional hazards model identified that CDO1 hypermethylation was prognostic factor as well as Ki-67 and hormone receptor status. The most intriguingly, CDO1 hypermethylation was of robust prognostic relevance in triple negative BC (p = 0.007). Promoter DNA methylation of CDO1 gene was robust prognostic indicator in primary BC patients with no prior chemotherapy. Prognostic relevance of the CDO1 promoter DNA methylation is worthy of being paid attention in triple negative BC cancer. 相似文献
78.
Thiago Aparecido da Silva Vania Sammartino Mariano Aline Sardinha-Silva Maria Aparecida de Souza Tiago Wilson Patriarca Mineo Maria Cristina Roque-Barreira 《PloS one》2016,11(2)
ArtinM is a D-mannose-binding lectin extracted from the seeds of Artocarpus heterophyllus that interacts with TLR2 N-glycans and activates antigen-presenting cells (APCs), as manifested by IL-12 production. In vivo ArtinM administration induces Th1 immunity and confers protection against infection with several intracellular pathogens. In the murine model of Candida albicans infection, it was verified that, in addition to Th1, ArtinM induces Th17 immunity manifested by high IL-17 levels in the treated animals. Herein, we investigated the mechanisms accounting for the ArtinM-induced IL-17 production. We found that ArtinM stimulates the IL-17 production by spleen cells in BALB/c or C57BL/6 mice, a response that was significantly reduced in the absence of IL-23, MyD88, or IL-1R. Furthermore, we showed that ArtinM directly induced the IL-23 mRNA expression and the IL-1 production by macrophages. Consistently, in cell suspensions depleted of macrophages, the IL-17 production stimulated by ArtinM was reduced by 53% and the exogenous IL-23 acted synergistically with ArtinM in promoting IL-17 production by spleen cell suspensions. We verified that the absence of IL-23, IL-1R, or MyD88 inhibited, but did not block, the IL-17 production by ArtinM-stimulated spleen cells. Therefore, we investigated whether ArtinM exerts a direct effect on CD4+ T cells in promoting IL-17 production. Indeed, spleen cell suspensions depleted of CD4+ T cells responded to ArtinM with very low levels of IL-17 release. Likewise, isolated CD4+ T cells under ArtinM stimulus augmented the expression of TGF-β mRNA and released high levels of IL-17. Considering the observed synergism between IL-23 and ArtinM, we used cells from IL-23 KO mice to assess the direct effect of lectin on CD4+ T cells. We verified that ArtinM increased the IL-17 production significantly, a response that was inhibited when the CD4+ T cells were pre-incubated with anti-CD3 antibody. In conclusion, ArtinM stimulates the production of IL-17 by CD4+ T cells in two major ways: (I) through the induction of IL-23 and IL-1 by APCs and (II) through the direct interaction with CD3 on the CD4+ T cells. This study contributes to elucidation of mechanisms accounting for the property of ArtinM in inducing Th17 immunity and opens new perspectives in designing strategies for modulating immunity by using carbohydrate recognition agents. 相似文献
79.
Al‐Sayed Al‐Soudy Tsuyoshi Nakanishi Seiya Mizuno Yoshikazu Hasegawa Hossam H. Shawki Megumi C. Katoh Walaa A. Basha Abdelaziz E. Ibrahim Hany A. El‐Shemy Hiroyoshi Iseki Atsushi Yoshiki Youhei Hiromori Hisamitsu Nagase Satoru Takahashi Hisashi Oishi Fumihiro Sugiyama 《Genesis (New York, N.Y. : 2000)》2016,54(7):389-397
Spermatogenesis is a complex and highly regulated process by which spermatogonial stem cells differentiate into spermatozoa. To better understand the molecular mechanisms of the process, the Cre/loxP system has been widely utilized for conditional gene knockout in mice. In this study, we generated a transgenic mouse line that expresses Cre recombinase under the control of the 2.5 kbp of the Prolactin family 3, subfamily b, member 1 (Prl3b1) gene promoter (Prl3b1‐cre). Prl3b1 was initially reported to code for placental lactogen 2 (PL‐2) protein in placenta along with increased expression toward the end of pregnancy. PL‐2 was found to be expressed in germ cells in the testis, especially in spermatocytes. To analyze the specificity and efficiency of Cre recombinase activity in Prl3b1‐cre mice, the mice were mated with reporter R26GRR mice, which express GFP ubiquitously before and tdsRed exclusively after Cre recombination. The systemic examination of Prl3b1‐cre;R26GRR mice revealed that tdsRed‐positive cells were detected only in the testis and epididymis. Fluorescence imaging of Prl3b1‐cre;R26GRR testes suggested that Cre‐mediated recombination took place in the germ cells with approximately 74% efficiency determined by in vitro fertilization. In conclusion, our results suggest that the Prl3b1‐cre mice line provides a unique resource to understand testicular germ‐cell development. genesis 54:389–397, 2016. © 2016 Wiley Periodicals, Inc. 相似文献
80.
Matsui S Satoh H Kawashima H Nagasaka S Niu CF Urushida T Katoh H Watanabe Y Hayashi H 《Canadian journal of physiology and pharmacology》2007,85(2):264-273
Aldosterone has non-genomic effects that express within minutes and modulate intracellular ion milieu and cellular function. However, it is still undefined whether aldosterone actually alters intracellular ion concentrations or cellular contractility. To clarify the non-genomic effects of aldosterone, we measured [Na+]i, Ca2+ transient (CaT), and cell volume in dye-loaded rat ventricular myocytes, and we also evaluated myocardial contractility. We found the following: (i) aldosterone increased [Na+]i at the concentrations of 100 nmol/L to 10 micromol/L; (ii) aldosterone (up to 10 micromol/L) did not alter CaT and cell shortening in isolated myocytes, developed tension in papillary muscles, or left ventricular developed pressure in Langendorff-perfused hearts; (iii) aldosterone (100 nmol/L) increased the cell volume from 47.5 +/- 3.6 pL to 49.8 +/- 3.7 pL (n=8, p<0.05); (iv) both the increases in [Na+]i and cell volume were blocked by a Na+-K+-2Cl- co-transporter (NKCCl) inhibitor, bumetanide, or by a Na+/H+ exchange (NHE) inhibitor, 5-(N-ethyl-N-isopropyl) amiloride; and (v) spironolactone by itself increased in [Na+]i and cell volume. In conclusion, aldosterone rapidly increased [Na+]i and cell volume via NKCC1 and NHE, whereas there were no changes in CaT or myocardial contractility. Hence the non-genomic effects of aldosterone may be related to cell swelling rather than the increase in contractility. 相似文献