全文获取类型
收费全文 | 3531篇 |
免费 | 220篇 |
国内免费 | 2篇 |
出版年
2021年 | 29篇 |
2020年 | 24篇 |
2019年 | 34篇 |
2018年 | 47篇 |
2017年 | 54篇 |
2016年 | 60篇 |
2015年 | 90篇 |
2014年 | 97篇 |
2013年 | 197篇 |
2012年 | 195篇 |
2011年 | 204篇 |
2010年 | 117篇 |
2009年 | 115篇 |
2008年 | 189篇 |
2007年 | 178篇 |
2006年 | 177篇 |
2005年 | 210篇 |
2004年 | 180篇 |
2003年 | 177篇 |
2002年 | 185篇 |
2001年 | 85篇 |
2000年 | 91篇 |
1999年 | 90篇 |
1998年 | 51篇 |
1997年 | 34篇 |
1996年 | 40篇 |
1995年 | 34篇 |
1994年 | 40篇 |
1993年 | 29篇 |
1992年 | 61篇 |
1991年 | 45篇 |
1990年 | 60篇 |
1989年 | 49篇 |
1988年 | 46篇 |
1987年 | 33篇 |
1986年 | 31篇 |
1985年 | 30篇 |
1984年 | 35篇 |
1983年 | 18篇 |
1982年 | 18篇 |
1980年 | 16篇 |
1979年 | 18篇 |
1978年 | 27篇 |
1977年 | 17篇 |
1976年 | 21篇 |
1975年 | 17篇 |
1974年 | 16篇 |
1973年 | 23篇 |
1972年 | 19篇 |
1970年 | 22篇 |
排序方式: 共有3753条查询结果,搜索用时 15 毫秒
151.
152.
Yukiko Tokitomo Yūko Shimono Akio Kobayashi Tei Yamanishi 《Bioscience, biotechnology, and biochemistry》2013,77(7):1873-1877
The attractive and characteristically sweet aroma components of baelfruit—a tropical fruit— were investigated. The aroma concentrates possessing the sweet floral and somewhat terpene-like aroma were obtained from both the pulp and peel of fresh baelfruits by means of lyophilization and ether extraction, being analyzed mainly by GC-MS, A total of 39 components were identified. Among these components, terpene alcohols and β-βonone were considered to contribute to the aroma of baelfruit. At optimum ripeness, the fruit with excellent flavor contained a large quantity of an isomeric compound of 3,7-dimethyl-1,5,7-octatrien-3-ol. This compound couldn’t be found in unripe fruit, and seems to be ?mportant in making the baelfruit flavor attractive. 相似文献
153.
Tei Yamanishi Michiko Kosuge Yukiko Tokitomo Ryoko Maeda 《Bioscience, biotechnology, and biochemistry》2013,77(9):2139-2142
The aroma constituents of the highest quality pouchong tea were characterized by GC–MS. Forty-eight components, including five newly identified compounds were characterized. GC peak area percentages of the main components in pouchong tea were compared with those of jasmine tea to differentiate compounds contributing to the aroma characteristics of pouchong tea with superior floral elegant flavor. Nerolidol, jasmine lactone, methyl jasmonate, indole, benzyl cyanide and linalool oxides were found in much higher concentration in pouchong tea than in jasmine tea. These compounds seemed to contribute to the aroma characteristics of the highest quality pouchong tea. 相似文献
154.
Yukiko Yamamoto Ryogo Toyoshima Keiichiro Muramatsu 《Bioscience, biotechnology, and biochemistry》2013,77(12):2585-2590
The supplementation of additional protein or methionine and threonine to a high tyrosinc-low protein diet has previously been shown to prevent the tyrosine toxicity. To elucidate the mechanism, studies were performed on the effect of these supplements on the capacity to oxidize excessive tyrosine. Male weanling rats were ad libitum fed a 10% casein diet containing 5% tyrosine with and without extra casein or methionine plus threonine for 7 days, then animals were injected intraperitoneally with l-tyrosine-U-14C and the oxidation rate to 14CO2 determined in vivo at an interval of several hours throughout a 24-hour period. The addition of extra casein or methionine and threonine to the high tyrosine diet enhanced the ability of tyrosine oxidation, and decreased the radioactivities of the TCA-soluble fractions in plasma, liver and muscle. A high level of free tyrosine in blood and tissues was also lowered by the addition of these supplements. The diurnal chenges in free tyrosine concentration of various tissues were observed. The data suggest that the beneficial effect of extra casein or methionine and threonine supplementation on tyrosine toxicity is due to an increased rate of tyrosine catabolism which results in lower tyrosine concentrations in body fluids which overcomes tyrosine toxicity. 相似文献
155.
Masaru Iizuka Yukiko Tsuji Takehiko Yamamoto 《Bioscience, biotechnology, and biochemistry》2013,77(1):213-215
This study examined the microbial transformation of carbazole (CZ) by an isolated bacterium that can use CZ as a sole carbon and nitrogen source. The strain identified as Pseudomonas stutzeri produced a large amount of anthranilic acid (AA) from CZ in the medium containing a nonionic surfactant. In dialysis culture using ion-exchange resin, 7.9 g/liter (58mm) of AA was accumulated from 15g/liter (90mm) of CZ and the molar yield of AA reached about 64%. 相似文献
156.
Yukiko Kawanabe Hisakazu Yamane Nobutaka Takahashi Teruko Nakamura 《Bioscience, biotechnology, and biochemistry》2013,77(8):2447-2450
GA3 was identified as a major GA in Neurospora crassa by gas chromatography/selected ion monitoring (GC/SIM) and its content was measured at various stages (0~96 hr after inoculation) of conidial germination and mycelial growth. The GA3 content in the fungus was 190ng/g dry weight at the initial stage and then decreased rapidly; that per liter culture decreased soon after the inoculation, and then increased to 17.6 ng 96 hr after inoculation. The GA3 concentration in the culture medium was around 10?11 m throughout the 96-hr incubation. The physiological role of endogenous GA in Neurospora crassa is also discussed. 相似文献
157.
Yoshimitsu Yamazaki Kuniaki Hosono 《Bioscience, biotechnology, and biochemistry》2013,77(8):2183-2186
1,2-Bis(methylthiomethyl)ferrocene (3) was oxidized by Corynebacterium equi IFO 3730 to give monosulfoxide 4 in two diastereomeric forms with (1S,2R,SS) and (1S,2R,RS) configurations in a ratio of 4:1, while 1,1′-bis(methylthiomethyl)ferrocene (5) was oxidized by Penicillium frequentans IFO 5692 to (R)-monosulfoxide 6 and then preferentially to (R,R)-bissulfoxide 7. Thus, the bacterial monooxygenase generated specific planar chirality in the metallocenic monosulfoxide, and the fungal enzyme formed C2 symmetry in the bissulfoxide. 相似文献
158.
Kunio Yamazaki 《Bioscience, biotechnology, and biochemistry》2013,77(9):1449-1458
Radioresistance of the spores of 46 strains of Bacillus was determined based on their dose-survival curves. The spores were produced on three kinds of sporulating medium.The variations in the radioresistance among species and strains were found, and also the radioresistance of spores depended upon the sporulating medium. The shapes of dose-survival curves are closely associated with the taxonomical groups of the genus Bacillus.Radioresistance of the spores showed no apparent correlation to their contents of dipicolinic acid, calcium and magnesium, but a slight correlation was observed between radioresistance and the molar ratio of Ca to DPA or Mg to Ca. Radioresistance of the spores in some groups correlated to their GC content, but no correlation was found in the other species. There was no correlation between heat resistance and radioresistance. 相似文献
159.
Akira Okubo Sunao Yamazaki Keiichiro Fuwa 《Bioscience, biotechnology, and biochemistry》2013,77(5):1173-1175
13C NMR spectra were measured for 19 pyrethroids and their related compounds including allethrin, tetramethrin, resmethrin, furamethrin, phenothrin and permethrin. Complete assignment of chemical shifts was accomplished by relative spectral pattern, single-frequency off-resonance decoupling, benzene substituent effects, proton selective decoupling and use of shift reagents. The use of shift reagent was found to be especially efficient for assignment of 13C resonances. In the case of allethrin, the splittings of some resonance peaks were observed originating from diastereomerism. 相似文献
160.
Takashi Utagawa Hirokazu Morisawa Shigeru Yamanaka Akihiro Yamazaki Fumihiro Yoshinaga Yoshio Hirose 《Bioscience, biotechnology, and biochemistry》2013,77(11):3239-3246
The properties of uridine Phosphorylase (UPase) and purine nucleoside Phosphorylase (PNPase) at high temperature were investigated. Both enzymes were found to be distributed in a wide range of bacteria and were partially purified from Enterobacter aerogenes AJ 11125 by heat treatment, ammonium sulfate fractionation and column chromatographies onDEAE-cellulose and Sephadex G-150. The UPase was purified 109-fold, and it showed an optimum pH of 8.5 and optimum temperature of 65°C, and activity toward uridine, 2′-deoxyuridine, thymidine and uracil arabinoside but not cytidine. The Km values of UPase for uridine were 0.7 mm at 40°C and 1.8 mm at 60°C. The PNPase was purified 83-fold, and it showed an optimum pH of 6.8 and optimum temperature of 60°C, and significant activity toward purine arabinosides as well as purine ribosides. The Km values of PNPase for inosine were 0.8 mm at 40°C and 2.2 mm at 60°C. 相似文献