全文获取类型
收费全文 | 2595篇 |
免费 | 214篇 |
国内免费 | 1篇 |
专业分类
2810篇 |
出版年
2022年 | 26篇 |
2021年 | 52篇 |
2020年 | 27篇 |
2019年 | 39篇 |
2018年 | 53篇 |
2017年 | 44篇 |
2016年 | 76篇 |
2015年 | 90篇 |
2014年 | 114篇 |
2013年 | 145篇 |
2012年 | 178篇 |
2011年 | 158篇 |
2010年 | 95篇 |
2009年 | 97篇 |
2008年 | 118篇 |
2007年 | 104篇 |
2006年 | 93篇 |
2005年 | 83篇 |
2004年 | 89篇 |
2003年 | 63篇 |
2002年 | 72篇 |
2001年 | 63篇 |
2000年 | 58篇 |
1999年 | 47篇 |
1998年 | 18篇 |
1997年 | 28篇 |
1996年 | 20篇 |
1993年 | 18篇 |
1992年 | 54篇 |
1991年 | 27篇 |
1990年 | 30篇 |
1989年 | 29篇 |
1988年 | 40篇 |
1987年 | 31篇 |
1986年 | 27篇 |
1985年 | 48篇 |
1984年 | 27篇 |
1983年 | 34篇 |
1982年 | 19篇 |
1981年 | 30篇 |
1980年 | 20篇 |
1979年 | 30篇 |
1978年 | 30篇 |
1977年 | 21篇 |
1976年 | 19篇 |
1975年 | 29篇 |
1974年 | 16篇 |
1973年 | 23篇 |
1972年 | 22篇 |
1971年 | 19篇 |
排序方式: 共有2810条查询结果,搜索用时 15 毫秒
71.
Nirupama Banerjee Rakesh Bhatnagar L. Viswanathan 《Applied microbiology and biotechnology》1981,11(4):226-228
Summary Furfural, a Maillard reaction product, was found to inhibit growth and alcohol production by Saccharomyces cerevisiae. Furfural concentrations above 1 mg ml–1 significantly decreased CO2 evolution by resuspended yeast cells. Important glycolytic enzymes such as hexokinase, phosphofructokinase, triosephosphate dehydrogenase, aldolase and alcohol dehydrogenase were assayed in presence of furfural. Dehydrogenases appeared to be the most sensitive enzymes and are probably responsible for the observed inhibition of alcohol production and growth. 相似文献
72.
Ranajit K. Banerjee 《Journal of biosciences》1981,3(3):231-238
The adenosine triphosphatase activity of the avian myeloblastosis virus obtained from the blood of the virus-infected chicken
was compared with that of the host cell myeloblasts. The specific activity of the viral enzyme is unusually higher than that
of the myeloblasts. A significant difference in inhibitor sensitivity was observed with quercetin. When the virus was grown
in chicken embryonic fibroblasts in culture, the resulting virus showed very little adenosine triphosphatase activity, comparable
to that of the fibroblasts and similar sensitivity to inhibitors. Antibody raised against the purified enzyme of avian myeloblastosis
virus inhibits the enzyme activity of the myeloblasts while the activity of the fibroblasts enzyme as well as that of fibroblast-grown
virus remains unaffected. 相似文献
73.
The effects of thyroid status on alpha-adrenergic receptors in the rat myocardium were investigated. The potent antagonist [3H]dihydroergokryptine was used to identify alpha-adrenergic receptors in rat heart particulate and sarcolemmal fractions. Administration of triiodothyronine to thyroidectomized rats decreased specific binding to alpha-adrenergic receptors in heart particulate and sarcolemmal fractions by 41% and 45%, respectively. Scatchard analysis revealed that the cardiac sarcolemmal fraction from thyroidectomized rats contained 29.3 fmol/mg of protein, as compared with 17.0 fmol/mg of protein found in the heart preparation of thyroidectomized rats treated with triiodothyronine. The equilibrium dissociation constants for the interaction of receptors with dihydroergokryptine were similar (about 1.5 nM) in the heart sarcolemmal fractions derived from these two groups of rats. The results of this study demonstrate that thyroid hormone can regulate the number of cardiac alpha-adrenergic receptors. In addition, there appears to be a reciprocal relationship between alpha-adrenergic and beta-adrenergic receptors in the rat myocardium. 相似文献
74.
The complete nucleotide sequence of the leader RNA synthesized in vitro by the Indiana serotype of vesicular stomatitis virus is presented. The sequence was determined by the technique described by Donis-Keller, Maxam and Gilbert (1977) in combination with the standard two-dimensional fingerprint techniques described by Barrell (1971). The leader RNA contains 48 nucleotides variably terminating at the 3′ terminus with cytosine (68%) and adenosine at position 47 (32%). Since the leader RNA is complementary to the 3′ terminal portion of the viral genome RNA, the first 48 nucleotides from the 3′ end of the genome RNA can be deduced. The leader RNA contains repetitive and palindromic sequences with a polypurine sequence at its 3′ terminus. The possible role of some of the sequences is discussed. 相似文献
75.
Hemagglutinating activity in extracts of mycelia from submerged mushroom cultures. 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Extracts from mycelia of seven different mushrooms agglutinated erythrocytes of several species. More than one agglutinating factor was identified in the extracts of three different mycelia. Agglutination was partially inhibited nonspecifically by high concentrations of glucose, galactose, mannose, fucose, and rhamnose. 相似文献
76.
Cultural conditions optimum for beta-galactosidase production by Saccharomyces anamensis are pH 4.5, temperature 26 +/- 2 degrees C, and 30 h of incubation period. Addition of lactose at 24 h fermentation greatly increase the level of enzyme. Optimum pHl, temperature, pH stability, and thermostability of yeast beta-galactosidase are negligibly affected by immobilization. The K(m) values of enzyme in the native and immobilized cells are 102mM and 148mM, respectively. Glucose noncompetitively inhibits the enzyme activity. Addition of substances such as dithioerythritol, glutathione, and bovine serum albumin to the native cell during assay procedure and immobilized cell prior to immobilization have stimulatory effects on enzyme activity. Metal ions like Ca(2+), Mg(2+) enhance the beta-galactosidase activity for both intact and bound cells. Immobilized cells retain 68.6% of the beta-galactosidase activity of intact cells and there is no significant loss of activity on storage at 4 degrees C for 28 days. 相似文献
77.
R Banerjee V Dhanaraj S K Mahanta A Surolia M Vijayan 《Journal of molecular biology》1991,221(3):773-776
Four new crystal forms of the anti-T lectin from jackfruit (Artocarpus integrifolia) have been prepared and characterized. Three of them, two monoclinic (P21, a = 59.4 A, b = 83.3 A, c = 63.5 A, beta = 107.7 degrees; C2, a = 106.1 A, b = 53.9 A, c = 128.0 A, beta = 95.0 A) and one orthorhombic (C222(1), a = 98.1 A, b = 67.3 A, c = 95.1 A) were grown with 2-methylpentan-2,4-diol (MPD) as the precipitant while the fourth, an hexagonal form (P6(1)22, a = b = 129.6 A, c = 157.9 A), was obtained in the presence of methyl-alpha-D-galactopyranoside with polyethylene glycol 4000 as the precipitant. The reported relative molecular mass (Mr) of the lectin was found to be inconsistent with the solvent content of the crystals estimated using measured densities. The Mr was redetermined using size-exclusion chromatography in the presence of methyl-alpha-D-galactopyranoside and Ferguson-plot analysis of mobilities in polyacrylamide gel electrophoresis. The redetermined Mr (66,000) is consistent with the measured crystal densities. The orthorhombic and the hexagonal forms, which have one half molecule and one molecule, respectively, in the asymmetric unit, are suitable for high-resolution X-ray analysis. 相似文献
78.
79.
There is a great deal of current interest in the role and importance of chirality in the development of new drugs, but little attention is being paid to the stereochemistry of older drugs. Indeed, many older chiral drugs were introduced without adequate information on their stereochemical identity or composition. We have examined one such drug, the antihypertensive diuretic agent cyclothiazide. Standard sources of drug information and the research literature do not provide data on the stereochemical composition of clinically used cyclothiazide, although scattered reports indicate that the drug may consist of "several stereoisomers." Inspection of the chemical structure of the drug, 6-chloro-3,4-dihydro-3-(5-norbornen-2-yl)-2H-1,2,4-benzothiadiazin e-7- sulfonamide 1,1-dioxide, shows that it can exist as eight stereoisomers that may form four racemates. Using synthesis, fast-atom-bombardment mass spectrometry, gas-liquid chromatography, chiral and nonchiral high-performance liquid chromatography, and nuclear magnetic resonance spectroscopy, we determined that pharmaceutical cyclothiazide is in fact a mixture of the eight stereoisomers in the form of the four racemates. The two racemates with endo configuration at the norbornene moiety predominate over the exo racemates, and small but significant differences in isomer distribution between different batches of the drug were observed. We urge that in studies of older drugs the stereochemical details be considered. 相似文献
80.
Dr. R. Banerjee Professor Dr. B. C. Bhattacharyya 《Bioprocess and biosystems engineering》1992,7(8):369-374
A newly isolated Rhizopus oryzae was found to exhibit some unusual phenomenon of secreting alkaline protease which was purified and characterized. The molecular weight was determined to be 28,600 dalton in gel electrophoresis. The enzyme is stable in the pH range from 3 to 11 and most active at pH 8. The temperature optimum of this thermostable biocatalyst is at 60 °C. The enzyme is sensitive to metal chelators, most of the metal ions (excepting a few monovalent cations) and inhibitor like PMSF. This indicates that the protease of isolated Rhizopus oryzae falls under alkaline serine group. 相似文献