全文获取类型
收费全文 | 2807篇 |
免费 | 120篇 |
国内免费 | 2篇 |
专业分类
2929篇 |
出版年
2022年 | 13篇 |
2021年 | 19篇 |
2020年 | 8篇 |
2019年 | 11篇 |
2018年 | 28篇 |
2017年 | 16篇 |
2016年 | 40篇 |
2015年 | 57篇 |
2014年 | 57篇 |
2013年 | 257篇 |
2012年 | 153篇 |
2011年 | 138篇 |
2010年 | 79篇 |
2009年 | 90篇 |
2008年 | 138篇 |
2007年 | 141篇 |
2006年 | 174篇 |
2005年 | 158篇 |
2004年 | 162篇 |
2003年 | 176篇 |
2002年 | 162篇 |
2001年 | 52篇 |
2000年 | 48篇 |
1999年 | 41篇 |
1998年 | 46篇 |
1997年 | 40篇 |
1996年 | 22篇 |
1995年 | 32篇 |
1994年 | 28篇 |
1993年 | 33篇 |
1992年 | 40篇 |
1991年 | 37篇 |
1990年 | 35篇 |
1989年 | 33篇 |
1988年 | 21篇 |
1987年 | 23篇 |
1986年 | 28篇 |
1985年 | 25篇 |
1984年 | 25篇 |
1983年 | 25篇 |
1982年 | 26篇 |
1981年 | 29篇 |
1980年 | 26篇 |
1979年 | 19篇 |
1978年 | 16篇 |
1977年 | 18篇 |
1976年 | 9篇 |
1975年 | 10篇 |
1973年 | 9篇 |
1969年 | 9篇 |
排序方式: 共有2929条查询结果,搜索用时 15 毫秒
201.
202.
Ryutaro Kakinuma Noriyuki Moriyama Yukio Muramatsu Shiho Gomi Masahiro Suzuki Hirobumi Nagasawa Masahiko Kusumoto Tomohiko Aso Yoshihisa Muramatsu Takaaki Tsuchida Koji Tsuta Akiko Miyagi Maeshima Naobumi Tochigi Shun-ichi Watanabe Naoki Sugihara Shinsuke Tsukagoshi Yasuo Saito Masahiro Kazama Kazuto Ashizawa Kazuo Awai Osamu Honda Hiroyuki Ishikawa Naoya Koizumi Daisuke Komoto Hiroshi Moriya Seitaro Oda Yasuji Oshiro Masahiro Yanagawa Noriyuki Tomiyama Hisao Asamura 《PloS one》2015,10(12)
203.
Tatsuya Unuma Akifumi Nakamura Keisuke Yamano Yukio Yokota 《Molecular reproduction and development》2010,77(1):59-68
Major yolk protein (MYP), the predominant component of yolk granules in sea urchin eggs, is also contained in the coelomic fluid and nutritive phagocytes of the gonad in both sexes. MYP is stored in ovarian and testicular nutritive phagocytes prior to gametogenesis and is used during gametogenesis as material for synthesizing proteins and other components necessary for eggs and sperm. To reveal the expression profile and the main production site of MYP, we analyzed MYP mRNA expression in immature and maturing Pseudocentrotus depressus. Real‐time reverse‐transcribed polymerase chain reaction analysis showed that MYP mRNA was expressed predominantly in the digestive tract (stomach, intestine and rectum) and the gonad of both sexes. The total amounts of MYP mRNA in the whole digestive tract and in the whole gonad were at similar levels in both immature and maturing sea urchins. MYP mRNA was also detected in white morula cells and vibratile cells separated from the coelomic fluid by density gradient centrifugation, but the expression levels in these cells were very low compared with those in the digestive tract and the gonad. Using in situ hybridization analysis, MYP mRNA was detected in the inner epithelium of the digestive tract and in nutritive phagocytes of the ovary and testis, but was not detected in the germ cells. We conclude that the adult sea urchin has two predominant production sites for MYP regardless of sex and reproductive stage: the inner epithelium of the digestive tract and the nutritive phagocytes of the gonad. Mol. Reprod. Dev. 77: 59–68, 2010. © 2009 Wiley‐Liss, Inc. 相似文献
204.
Kumi Nagaoka Yoshiaki Kitamura Yoshihito Ueno Yukio Kitade 《Bioorganic & medicinal chemistry letters》2010,20(3):1186-1188
Human ribonuclease L (RNase L), an interferon-induced endoribonuclease, becomes enzymatically active after binding to 2-5A. The 5′-phosphoryl group of 2-5A is reportedly necessary for the conformational change leading to RNase L activation. However, we found that 5′-O-dephosphorylated 2-5A tetramer analogs with 8-methyladenosine at the 2′-terminus were more effective as an activator of RNase L than the parent 2-5A tetramer. Introduction of 8-methyladenosine is thought to induce a dramatic shift of 2-5A in the binding site of RNase L. 相似文献
205.
Kenjiro Asagoshi Yuan Liu Aya Masaoka Li Lan Rajendra Prasad Julie K. Horton Ashley R. Brown Xiao-hong Wang Hussam M. Bdour Robert W. Sobol John-Stephen Taylor Akira Yasui Samuel H. Wilson 《DNA Repair》2010,9(2):109-119
We examined a role for DNA polymerase β (Pol β) in mammalian long patch base excision repair (LP BER). Although a role for Pol β is well known in single-nucleotide BER, information on this enzyme in the context of LP BER has been limited. To examine the question of Pol β involvement in LP BER, we made use of nucleotide excision repair-deficient human XPA cells expressing UVDE (XPA-UVDE), which introduces a nick directly 5′ to the cyclobutane pyrimidine dimer or 6-4 photoproduct, leaving ends with 3′-OH and 5′-phosphorylated UV lesion. We observed recruitment of GFP-fused Pol β to focal sites of nuclear UV irradiation, consistent with a role of Pol β in repair of UV-induced photoproducts adjacent to a strand break. This was the first evidence of Pol β recruitment in LP BER in vivo. In cell extract, a 5′-blocked oligodeoxynucleotide substrate containing a nicked 5′-cyclobutane pyrimidine dimer was repaired by Pol β-dependent LP BER. We also demonstrated Pol β involvement in LP BER by making use of mouse cells that are double null for XPA and Pol β. These results were extended by experiments with oligodeoxynucleotide substrates and purified human Pol β. 相似文献
206.
Shigetaka Kitajima Yukio Yasukochi Shigeki Minakami 《Archives of biochemistry and biophysics》1981,210(1):330-339
An NADH:(acceptor) oxidoreductase (EC 1.6.99.3) of human erythrocyte membrane was purified by DEAE-cellulose anion exchange, hydroxyapatite adsorption, and 5′-ADP-hexane-agarose affinity chromatographies after solubilization with Triton X-100. The purified reductase preparation was homogeneous and estimated to have an apparent molecular weight of 36,000 on SDS-polyacrylamide slab gel electrophoresis and of 144,000 on Sephadex G-200 gel filtration in the presence of 0.2% Triton X-100, whereas a soluble NADH-cytochrome b5 reductase of human erythrocyte had a molecular weight of 32,000 by both methods, indicating the existence of a distinct membrane reductase. Digestion of the membrane reductase with cathepsin D yielded a new polypeptide chain which gave the same relative mobility as the soluble reductase on SDS-polyacrylamide slab gel electrophoresis. The membrane enzyme, the cathepsin-digested enzyme, and the soluble enzyme all cross-reacted with the antibody to rat liver microsomal NADH-cytochrome b5 reductase. The enzyme had one mole FAD per 36,000 as a prosthetic group and could reduce K3Fe(CN)6, 2,6-dichlorophenolindophenol, cytochrome c, methemoglobin-ferrocyanide complex, cytochrome b5 and methemoglobin via cytochrome b5 when NADH was used as an electron donor. NADPH was less effective as an electron donor than NADH. The specific activity of the purified enzyme was 790 μmol ferricyanide reduced min?1 mg?1 and the turnover number was 40,600 mol ferricyanide reduced min?1 mol?1 FAD at 25 °C. The apparent Km values for NADH and cytochrome b5 were 0.6 and 20 μm, respectively, and the apparent V value was 270 μmol cytochrome b5 reduced min?1 mg?1. These kinetic properties were similar to those of the soluble NADH-cytochrome b5 reductase. The results indicate that the NADH:(acceptor) oxidoreductase of human erythrocyte membrane could be characterized as a membrane NADH-cytochrome b5 reductase. 相似文献
207.
208.
Suppressive effect of a hot water extract of adzuki beans (Vigna angularis) on hyperglycemia after sucrose loading in mice and diabetic rats 总被引:3,自引:0,他引:3
Itoh T Kita N Kurokawa Y Kobayashi M Horio F Furuichi Y 《Bioscience, biotechnology, and biochemistry》2004,68(12):2421-2426
A hot water extract obtained by boiling adzuki beans (Vigna angularis) to produce bean paste for Japanese cake showed inhibitory activity against alpha-glucosidase, alpha-amylase, maltase, sucrase, and isomaltase after HP-20 column chromatography. The IC(50) values for each hydrolylase were 0.78 mg/ml (alpha-amylase), 2.45 mg/ml (maltase), 5.37 mg/ml (sucrase), and 1.75 mg/ml (isomaltase). The active fraction showed potential hypoglycemic activity in both normal mice and streptozotocin (STZ)-induced diabetic rats after an oral administration of sucrose, but did not show any effect on the blood glucose concentration after glucose administration, suggesting that the active fraction suppressed the postprandial blood glucose level by inhibiting alpha-glucosidase and alpha-amylase, irrespective of the endogenous blood insulin level. 相似文献
209.
Susumu Oi Ichiro Konishi Yukio Satomura 《Bioscience, biotechnology, and biochemistry》2013,77(3):266-273
“Isosclerotan”, a polysaccharide constituent extracted with a sodium hydroxide solution from sclerotia of Sclerotinia libertiana, could be purified by the successive precipitation with the followings; a mixture of copper sulfate and sodium hydroxide, ammonium sulfate, and ethyl alcohol. The preparation proved homogeneous by ultracentrifugal analysis. From sedimentation and viscosity measurements, the molecular weight of isosclerotan was calculated as 6.13 × 106, andas 1.60 × 105 after treatment with a dilute oxalic acid solution. Isosclerotan was scarecely soluble in cold water but soluble in hot water, yielding a highly viscous solution. It exhibited a low positive optical rotation, + 23.0° (in water), and infrared spectrum had a sharp absorption at 890~898 cm?1, which indicated the prevalence of the β-glycosidic linkage in isosclerotan. Through degradation by acids and enzymes of isosclerotan, there were obtained various oligosaccharides containing β-1.3, β-1.4, and β-1.6 linkages. From results obtained by periodate oxidation and methylation, it is assumed that the polysaccharide involves the 1.3, 1.4, and 1.6 linkages in 47.7%, 16.6% and 35.7%, respectively, and a branching structure about 12.5%. 相似文献
210.
A new genus, Versicolorisporium, is established for the coelomycetous fungus collected in Japan on dead culms of the bamboos Pleioblastus chino and Sasamorpha borealis. The type species of the genus, V. triseptatum, is characterized by the production of holoblastic, 3-septate, obovoid, versicolored conidia. Versicolorisporium is similar to Toxosporiella, Neohendersonia, Toxosporiopsis, and Scolicosporium in having versicolored conidia, but differs from these genera by the uniloculate pycnidial conidiomata with a periphysate
ostiole, lacking paraphyses, and the conidia without black-banded septa. A BLAST search using LSU nrDNA sequence indicates
that the new genus is a member of Pleosporales, Dothideomycetes. 相似文献