全文获取类型
收费全文 | 374篇 |
免费 | 34篇 |
专业分类
408篇 |
出版年
2021年 | 4篇 |
2020年 | 7篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 10篇 |
2014年 | 13篇 |
2013年 | 20篇 |
2012年 | 8篇 |
2011年 | 9篇 |
2010年 | 10篇 |
2009年 | 14篇 |
2008年 | 15篇 |
2007年 | 14篇 |
2006年 | 21篇 |
2005年 | 6篇 |
2004年 | 7篇 |
2003年 | 13篇 |
2002年 | 14篇 |
2001年 | 16篇 |
2000年 | 13篇 |
1999年 | 11篇 |
1998年 | 10篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1986年 | 4篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 8篇 |
1980年 | 2篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 9篇 |
1973年 | 4篇 |
1971年 | 2篇 |
1970年 | 7篇 |
1969年 | 4篇 |
1967年 | 2篇 |
1966年 | 5篇 |
排序方式: 共有408条查询结果,搜索用时 0 毫秒
81.
Transformation of steroids by fungal protoplasts 总被引:4,自引:0,他引:4
Leon Sedlaczek Jerzy Długoński Adam Jaworski 《Applied microbiology and biotechnology》1984,20(3):166-169
Summary Protoplasts of Cunninghamella elegans transformed cortexolone to the same products as did the mycelium. Transformation of the steroid by non-induced mycelium and by protoplasts released from it was almost completely inhibited by cycloheximide. However, hydroxylation of cortexolone was not affected by this antibiotic if mycelium grown in the presence of an enzyme inducer or protoplasts obtained from the induced mycelium were used. The transformation rate of protoplasts, on the basis of dry weight or protein units, was about four times higher than that of the mycelium, indicating that the mycelial cell wall was a serious rate-limiting factor in steroid bioconversion. 相似文献
82.
83.
84.
85.
Acute urinary tract infection may be preceded by and active pyelonephritis may be associated with asymptomatic bacteriuria. Treatment of asymptomatic bacteriuria may prevent or arrest active, chronic pyelonephritis and its sequelae. Consequently, there is a need for a reliable and simple screening procedure to detect asymptomatic bacteriuria in large segments of the population.The reliability and practicability of tests advocated for the detection of bacteriuria, including the new chemical triphenyltetrazolium chloride (T.T.C.) (Uroscreen) test, were evaluated. Reliability was assessed by correlating results of these tests with bacterial counts of tested urines. Significant bacteriuria is defined as the presence of 100,000 or more organisms per ml. of urine.The T.T.C. (Uroscreen) test was positive in 92.5% of cases of bacteriuria; there were 7.5% false-negative and 2.8% false-positive results. Bacteria on Gram-stained smear were found in 95.5% of the cases of bacteriuria and in 14.6% of those with non-infected urine; pyuria (more than three leukocytes per high-power field), in 60% of those with bacteriuria and in 15.9% of those with presumably non-infected urine. Bacteria were conspicuous in the urinary sediment in 91.1% of cases of bacteriuria and in 3.7% of presumably non-infected urines.The T.T.C. (Uroscreen) test fulfilled the criteria for a reliable and simple screening procedure. It should be used concomitantly with other screening tests when the urine is examined routinely. 相似文献
86.
87.
The demonstration that interleukin 2 (IL-2) is a lectin specific for
oligomannosides allows to understand a new function for this cytokine: as a
bifunctional molecule when bound to its receptor ss, IL-2 associates the
latter which the CD3/TCR complex, interacting with oligosaccharides of CD3
through its carbohydrate-recognition domain (Zanetta et al. , 1996,
Biochem. J., 318, 49-53). This induces the tyrosine phosphorylation of the
IL-2R beta by ++p56(lck) , the first step of the IL-2-dependent signaling.
Since this specific association is disrupted in vitro by oligomannosides
with five and six mannose residues, we made the hypothesis that pathogenic
cells or microorganisms could bind IL-2, consequently disturbing the IL-2-
dependent response. This study shows that the pathogenic yeast Candida
albicans (in contrast with nonpathogenic yeasts) binds high amounts of IL-2
as did cancer cells. In contrast with cancer cells, yeasts do not bind the
Man6GlcNAc2-specific lectin CSL, an endogenous "amplifier of activation
signals" (Zanetta et al. , 1995, Biochem. J., 311, 629-636).
相似文献
88.
SUMMARY 1. Unialgal cultures of three species common in the freshwater phytoplankton were used to test limitation of specific growth rate and final yield in defined media of low K+ concentration (range <0.3–6 μmol L−1 or mmol m−3 ).
2. Growth rate of the diatom Asterionella formosa was independent of K+ concentration above 0.7 μmol L−1 . Final yield was dependent on initial concentration when accompanied by K+ depletion below this concentration, but not by lesser depletion with more residual K+ . Analyses of particulate K in the biomass indicated a mean final cell content of 2.8 μmol K 10−8 cells, approximately 1.0% of the organic dry weight.
3. Less detailed work with the diatom Diatoma elongatum showed no dependence of growth rate or final yield upon the initial K+ concentration in the range 0.8–3.2 μmol L−1 . The phytoflagellate Plagioselmis nannoplanctica suffered net mortality in the lowest concentration tested, 0.8 μmol L−1 .
4. Comparison with the range of K+ concentration in natural fresh waters, including a depletion induced by an aquatic macrophyte, suggests that K+ is unlikely to limit growth of phytoplankton. Nevertheless, there can be correlation of K+ with lake trophy. 相似文献
2. Growth rate of the diatom Asterionella formosa was independent of K
3. Less detailed work with the diatom Diatoma elongatum showed no dependence of growth rate or final yield upon the initial K
4. Comparison with the range of K
89.
Agarose and polyacrylamide gel electrophoresis of a total alpaca (Lama pacos) DNA, digested with several restriction enzymes, revealed the presence of two tandemly organized repetitive DNA sequences, named Satellite I and Satellite II. Three Xhol-monomers from Satellite I DNA and two BspRI-monomers from Satellite II DNA were sequenced. As determined by dot hybridization analysis, the total alpaca DNA consists of 3.4% and 1.3% Satellites I and II, respectively. Computer search revealed no homology to any primate, rodent or mammalian sequences published in the Gen Bank Release 48.0 (February 1987) and the EMBL Bank Release 10 (December 1986). 相似文献
90.