全文获取类型
收费全文 | 659篇 |
免费 | 47篇 |
国内免费 | 1篇 |
出版年
2021年 | 6篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2016年 | 14篇 |
2015年 | 19篇 |
2014年 | 20篇 |
2013年 | 49篇 |
2012年 | 32篇 |
2011年 | 32篇 |
2010年 | 36篇 |
2009年 | 34篇 |
2008年 | 23篇 |
2007年 | 22篇 |
2006年 | 21篇 |
2005年 | 26篇 |
2004年 | 19篇 |
2003年 | 8篇 |
2002年 | 16篇 |
2001年 | 12篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1998年 | 14篇 |
1997年 | 16篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 12篇 |
1984年 | 14篇 |
1983年 | 13篇 |
1982年 | 22篇 |
1981年 | 12篇 |
1980年 | 12篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1972年 | 7篇 |
1971年 | 5篇 |
1970年 | 6篇 |
1969年 | 5篇 |
1968年 | 3篇 |
排序方式: 共有707条查询结果,搜索用时 171 毫秒
611.
Summary Construction of translational fusions betwen the repA gene of plasmid R 1 (required for replication) and the lacZ gene has allowed a quantitative analysis of expression of this gene. It is suggested that the replication of R 1 is controlled by two replication control functions acting as inhibitors of repA expression. 相似文献
612.
613.
Mice of the TO Swiss strain received diets containing different amounts of saturated or unsaturated fat throughout life. These diets produced characteristic changes in cardiac phospholipid fatty acid composition, but produced no significant differences in fatty acid composition of phospholipids from a crude membrane fraction of brain. When littermates of these animals were exposed to ethanol vapour in an inhalation chamber it was observed that mice which had received a diet high in saturated fat lost the righting reflex at an estimated concentration of ethanol in blood higher than that required for mice receiving a control diet, or a diet rich in polyunsaturated fat. Analysis of the brain membrane fraction from those animals which had received ethanol revealed that mice receiving the highly saturated fat diet now had a significantly greater proportion of saturated fatty acids in brain membrane phospholipids. These results are discussed in relation to the hypothesis that brain membrane lipid composition may influence the behavioural response to ethanol. 相似文献
614.
A cloned polyoma DNA fragment representing the 5'' half of the early gene region is oncogenic. 总被引:8,自引:7,他引:1
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The two polyoma DNA fragments generated by cleavage with BamHI and EcoRI were cloned in pBR322, and their oncogenic potential was tested in vivo and in vitro. Only recombinant plasmid DNA containing a polyoma DNA fragment which extends clockwise from 58 to 0 map units and include approximately the 5'-proximal half of the early gene region produced tumors in newborn hamsters and transformed rat embryo cells in tissue culture. Southern blotting analysis indicated that the entire 2.2-kilobase polyoma BamHI-EcoRI fragment was intact in both a tumor cell line and a cell line transformed in culture which we examined. The presence of polyoma middle and small T antigen in these lines was demonstrated by immunoprecipitation and tryptic peptide mapping. DNA from a recombinant plasmid containing a polyoma genome deleted between 90 and 4 map units failed to induce tumors or transform cells. 相似文献
615.
A component, termed pyridinoline, has been reported to be derived from 'lysine aldehyde' (2,6-diaminohexanaldehyde) and designated as the stable cross-link of mature collagen. Commerically prepared collagen and freshly obtained mature bovine tendon collagen were both investigated with regard to their pyridinoline content. Both sources of material could be depleted of this component by mild washing procedures. Pepsin-solubilized collagen and peptides derived from CNBr cleavage of intact collagen did not contain the compound. Pure pyridinoline was isolated and shown to be hydrolysed by water, as previously reported, but neither hydroxylysine nor lysine could be ds not a cross-linking component of collagen. 相似文献
616.
D.B. Light M.R. Adler J.K. Ter Beest S.A. Botsford R.T. Gronau 《The Journal of membrane biology》1998,166(2):119-132
This study examined whether protein kinase C (PKC) stimulates K+ efflux during regulatory volume decrease (RVD) in Necturus maculosus (mudpuppy) red blood cells (RBCs). The limit of osmotic fragility increased with the general protein kinase inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine
(H-7, 10 μm), but not with the cyclic nucleotide-dependent kinase antagonists N-(2′-guanidinoethyl)-5-isoquinolinesulfonamide (HA-1004,
10 μm) and N-2-(methylamino)ethyl-5-isoquinoline-sulfonamide (H-8, 5 μm). Consistent with these results, osmotic fragility also increased with the PKC antagonists bisindolylmaleimide I (GF-109203X
or bis I, 100 nm), bisindolylmaleimide II (bis II, 100 nm), and chelerythrine (10 μm). The effect of these three antagonists and H-7 was reversed with gramicidin (5 μm in a choline Ringer), indicating PKC was linked to K+ efflux (gramicidin is a cationophore that was used to ensure a high K+ permeability). We also measured cell volume recovery from hypotonic shock (0.5× Ringer) with a Coulter counter and estimated
cell volume from the hematocrit. The percent RVD compared to control decreased with H-7 (10 μm), sphingosine (100 nm), chelerythrine (10 μm), bis I (100 nm), and bis II (100 nm), but not with HA-1004 (10 μm) nor H-8 (5 μm). Inhibition of RVD by H-7, chelerythrine, bis I, and bis II was reversed with gramicidin (5 μm). Furthermore, using the patch clamp technique, we found H-7 (10 μm) reduced a whole cell conductance that was activated during cell swelling. In addition, a conductance responsible for K+ efflux during cell swelling was inhibited by bis I (100 nm) and bis II (100 nm). These results indicate that a conductive pathway mediating K+ loss during RVD is regulated, at least in part, by protein kinase C.
Received: 20 January 1998/Revised: 2 September 1998 相似文献
617.
Electroantennogram (EAG) studies demonstrated that antennae of both male and female Trichoplusia ni have: (1) receptor-neurones sensitive to female pheromone, (2) a low response threshold, (3) an identical mean-percentage EAG curve over a broad concentration range of pheromone, and (4) a similar absolute recovery interval from adaptation to pheromonal stimulation. These factors suggest that antennae of male and female T. ni have homologous and homogeneous acceptor sites for the female pheromone. Pheromonal stimulation of female antennae elicited EAGs with only 25% of the amplitude of those elicited in males. 相似文献
618.
619.
Effects of context on judgements of odor intensities in humans 总被引:2,自引:2,他引:0
This study evaluated whether the intensity of previously smelled odors
could unintentionally influence the subsequent judgement of odor intensity.
The predicted context effect was based on the adaptation- level theory.
Before and 25 min after either WEAK or STRONG biasing odor concentrations,
51 subjects were required to rate the intensity of 10 different odor
concentrations of California Orange Oil. After the WEAK bias, subjects
judged the odor intensity as being stronger than they did after the STRONG
bias. Thus the intensity of odors smelled 25 min earlier can
unintentionally influence subsequent odor intensity judgement. The findings
are discussed in the light of two alternative explanations, namely, a
central implicit memory process and a stimulus- level-based change at the
peripheral level.
相似文献
620.
Luisa María Sierra Albert Pastink Madeleine JM Nivard Ekkehart W. Vogel 《Molecular & general genetics : MGG》1993,237(3):370-374
Summary The DNA base sequence changes induced by diethyl sulfate (DES) were analyzed in postmeiotic male germ cells of Drosophila melanogaster. 31 transmissible vermilion mutants were recovered in F1 and F2 generations, with a frequency of 2.6 × 10–4 for the F1, and of 1.8–13 × 10–4 for the F2. The results show that DES induces both base pair substitutions (93%) and deletions (7%). In accord with its relatively high ability to alkylate oxygens in DNA, the most frequent type of sequence alteration among the basepair changes are GC-AT transitions, accounting for 73% of mutations, followed by transversions AT-TA (10%). DES also induced AT-GC transitions and AT-CG transversions. Both induced deletions were intralocus deletions, not occurring between basepair repeats. No influence of neighboring bases on the mutation position was found. 相似文献