全文获取类型
收费全文 | 7459篇 |
免费 | 690篇 |
国内免费 | 9篇 |
出版年
2022年 | 52篇 |
2021年 | 98篇 |
2020年 | 87篇 |
2019年 | 77篇 |
2018年 | 105篇 |
2017年 | 89篇 |
2016年 | 134篇 |
2015年 | 236篇 |
2014年 | 284篇 |
2013年 | 371篇 |
2012年 | 457篇 |
2011年 | 488篇 |
2010年 | 319篇 |
2009年 | 271篇 |
2008年 | 396篇 |
2007年 | 432篇 |
2006年 | 411篇 |
2005年 | 413篇 |
2004年 | 365篇 |
2003年 | 342篇 |
2002年 | 377篇 |
2001年 | 83篇 |
2000年 | 93篇 |
1999年 | 114篇 |
1998年 | 111篇 |
1997年 | 72篇 |
1996年 | 67篇 |
1995年 | 73篇 |
1994年 | 64篇 |
1993年 | 58篇 |
1992年 | 71篇 |
1991年 | 62篇 |
1990年 | 69篇 |
1989年 | 58篇 |
1988年 | 53篇 |
1987年 | 46篇 |
1986年 | 38篇 |
1985年 | 54篇 |
1984年 | 48篇 |
1983年 | 57篇 |
1982年 | 56篇 |
1981年 | 59篇 |
1980年 | 62篇 |
1979年 | 44篇 |
1978年 | 38篇 |
1977年 | 28篇 |
1976年 | 45篇 |
1975年 | 45篇 |
1974年 | 30篇 |
1973年 | 29篇 |
排序方式: 共有8158条查询结果,搜索用时 109 毫秒
101.
Kathleen D. Murray Eleanor Groden Francis A. Drummond A. Randall Alford Richard H. Storch Michael D. Bentley 《Entomologia Experimentalis et Applicata》1996,80(3):503-510
The effects of citrus limonoids, applied topically to potato (Solanum tuberosum L. var. Katahdin) foliage, on Colorado potato beetle (Leptinotarsa decemlineata) (Say) (Chrysomelidae) larval development, growth, and survival were quantified in laboratory assays and a small-plot field test. In laboratory assays, survival, development rate, and body weight decreased with increasing limonoid concentration, however these measures of larval response did not significantly differ among varying periods of limonoid exposure (three, six, or nine days). Significant limonoid application concentration and frequency effects on survival, development rate, and defoliation were observed in the field test. These results indicate the potential utility of lethal and non-lethal effects of citrus limonoids for management of the Colorado potato beetle. 相似文献
102.
Transformation of the extremely thermoacidophilic archaeon Sulfolobus solfataricus via a self-spreading vector 总被引:1,自引:0,他引:1
Abstract The comparative chromosomal locations of polymeric β-fructosidase SUC genes have been determined by Southern blot hybridization with the SUC2 probe in 91 different strains of Saccharomyces cerevisiae . Most of the strains exhibited a single SUC2 gene, but in some strains two or three SUC genes were found. All Suc− strains carried a silent suc20 sequence. The accumulation of SUC genes was observed in populations derived from sources containing sucrose and seems to be absent in strains from sources promoting the MEL gene. 相似文献
103.
The prevalence of gentamicin 2'-N-acetyltransferase in the Proteeae and its role in the O-acetylation of peptidoglycan 总被引:1,自引:0,他引:1
Abstract The prevalence of aac(2')-Ia , a gene coding for gentamicin 2'-JV-acetyltransferase in Providenda stuartii , among species of the Proteeae was investigated to determine if it is a common resistance factor and whether the correlation observed in P. stuartii between its expression and the levels of peptidoglycan O -acetylation represents a general feature of bacteria producing this form of modified peptidoglycan. An evaluation of the MICs of gentamicin for each of the species of the Proteeae did not reveal any apparent relationship between resistance and the degree of O-acetylation of peptidoglycan. The entire aac(2')-Ia gene was used as a probe in Southern hybridization experiments against genomic DNA from each species of the Proteeae. A sequence with strong homology to aac(2')-Ia was present only in Proteus penneri while weak hybridization was also observed to the restriction digested DNA from Providenda rettgeri . Other bacteria that O -acetylate peptidoglycan were also screened with this probe and a homologous DNA sequence was only found in Neisseria subflava . These data suggest that AAC(2')-Ia may contribute to the rO -acetylation of peptidoglycan in P. stuartii , but a more specific enzyme must also be produced for this function. 相似文献
104.
Cell Envelope Changes in Solvent-Tolerant and Solvent-Sensitive Pseudomonas putida Strains following Exposure to o-Xylene 总被引:4,自引:1,他引:3
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)
Solvent-tolerant and -sensitive Pseudomonas putida strains were studied to determine their cell envelope changes following exposure to o-xylene. Both strains produced trans-unsaturated fatty acids. The tolerant strain showed an increase in total fatty acids, an increase in saturated fatty acids, and modified lipopolysaccharide. It is suggested that these envelope modifications aid in survival at high concentrations of organic solvents. 相似文献
105.
106.
107.
Gellerich Frank Norbert Kapischke Matthias Kunz Wolfram Neumann Wolfram Kuznetsov Andrey Brdiczka Dieter Nicolay Klaas 《Molecular and cellular biochemistry》1994,133(1):85-104
Summary Cytosolic proteins as components of the physiological mitochondrial environment were substituted by dextrans added to media normally used for incubation of isolated mitochondria. Under these conditions the volume of the intermembrane space decreases and the contact sites between the both mitochondrial membranes increase drastically. These morphological changes are accompanied by a reduced permeability of the mitochondrial outer compartment for adenine nucleotides as it was shown by extensive kinetic studies of mitochondrial enzymes (oxidative phosphorylation, mi-creatine kinase, mi-adenylate kinase). The decreased permeability of the mitochondrial outer membrane causes increased rate dependent concentration gradients in the micromolar range for adenine nucleotides between the intermembrane space and the extramitochondrial space. Although all metabolites crossing the outer membrane exhibit the same concentration gradients, considerable compartmentations are detectable for ADP only due to its low extramitochondrial concentration. The consequences of ADP-compartmentation in the mitochondrial intermembrane space for ADP-channelling into the mitochondria are discussed. 相似文献
108.
109.
A. M. Theodosiou K. E. Morrison A. M. Nesbit R. J. Daniels L. Campbell M. J. Francis Z. Christodoulou K. E. Davies 《American journal of human genetics》1994,55(6):1209-1217
Childhood-onset proximal spinal muscular atrophy (SMA) is a heritable neurological disorder, which has been mapped by genetic linkage analysis to chromosome 5q13, in the interval between markers D5S435 and D5S557. Here, we present gene sequences that have been isolated from this interval, several of which show sequence homologies to exons of beta-glucuronidase. These gene sequences are repeated several times across the candidate region and are also present on chromosome 5p. The arrangement of these repetitive gene motifs is polymorphic between individuals. The high degree of variability observed may have some influence on the expression of the genes in the region. Since SMA is not inherited as a classical autosomal recessive disease, novel genomic rearrangements arising from aberrant recombination events between the complex repeats may be associated with the phenotype observed. 相似文献
110.