全文获取类型
收费全文 | 4670篇 |
免费 | 518篇 |
出版年
2022年 | 36篇 |
2021年 | 66篇 |
2020年 | 34篇 |
2019年 | 44篇 |
2018年 | 62篇 |
2017年 | 49篇 |
2016年 | 86篇 |
2015年 | 131篇 |
2014年 | 156篇 |
2013年 | 190篇 |
2012年 | 240篇 |
2011年 | 253篇 |
2010年 | 178篇 |
2009年 | 144篇 |
2008年 | 222篇 |
2007年 | 222篇 |
2006年 | 178篇 |
2005年 | 183篇 |
2004年 | 173篇 |
2003年 | 182篇 |
2002年 | 166篇 |
2001年 | 91篇 |
2000年 | 99篇 |
1999年 | 91篇 |
1998年 | 59篇 |
1997年 | 51篇 |
1996年 | 40篇 |
1995年 | 51篇 |
1994年 | 43篇 |
1993年 | 50篇 |
1992年 | 79篇 |
1991年 | 61篇 |
1990年 | 76篇 |
1989年 | 74篇 |
1988年 | 77篇 |
1987年 | 65篇 |
1986年 | 55篇 |
1985年 | 55篇 |
1984年 | 55篇 |
1983年 | 45篇 |
1982年 | 51篇 |
1981年 | 49篇 |
1979年 | 57篇 |
1978年 | 44篇 |
1977年 | 32篇 |
1976年 | 49篇 |
1975年 | 51篇 |
1974年 | 60篇 |
1973年 | 76篇 |
1972年 | 53篇 |
排序方式: 共有5188条查询结果,搜索用时 46 毫秒
11.
Jood Illse Hoff Justin Wallace Setati Mathabatha Evodia 《World journal of microbiology & biotechnology》2017,33(7):1-11
World Journal of Microbiology and Biotechnology - The current study is the first one to demonstrate the wine fermentation potential of members of several species of the genus Kazachstania including... 相似文献
12.
13.
The complete nucleotide sequence of the mitochondrial (mt) genome was determined for specimens of the coral species Montipora
cactus (Bernard 1897) and Anacropora
matthai (Pillai 1973), representing two morphologically distinct genera of the family Acroporidae. These sequences were compared
with the published mt genome sequence for the confamilial species, Acropora tenuis (Dana 1846). The size of the mt genome was 17,887 bp and 17,888 bp for M. cactus and A. matthai. Gene content and organization was found to be very similar among the three Acroporidae mt genomes with a group I intron
occurring in the NADH dehyrogenase 5 (nad5) gene. The intergenic regions were also similar in length among the three corals. The control region located between the
small ribosomal RNA (ms) and the cytochrome oxidase 3 (cox3) gene was significantly smaller in M. cactus and A. matthai (both 627 bp) than in A. tenuis (1086 bp). Only one set of repeated sequences was identified at the 3′-end of the control regions in M. cactus and A. matthai. A lack of the abundant repetitive elements which have been reported for A. tenuis, accounts for the relatively short control regions in M. cactus and A. matthai. Pairwise distances and relative rate analyses of 13 protein coding genes, the group I intron and the largest intergenic
region, igr3, revealed significant differences in the rate of molecular evolution of the mt genome among the three species, with an extremely
slow rate being seen between Montipora and Anacropora. It is concluded that rapid mt genome evolution is taking place in genus Acropora relative to the confamilial genera Montipora and Anacropora although all are within the relatively slow range thought to be typical of Anthozoa. 相似文献
14.
15.
16.
17.
Serotonergic projections from the raphe nuclei are thought to modulate locomotor activity in the rat, and serotonin injection into the nucleus accumbens attenuates the hypermotility elicited by amphetamine. The purpose of the present study was to characterize the effects of various classes of serotonergic agonists administered into the nucleus accumbens on d-amphetamine-stimulated locomotor activity in order to determine which serotonin receptor subtypes are involved. Administration of the nonselective 5-HT agonist quipazine, the 5-HT-1 agonist mCPP, the 5-HT-1a agonist 8-OH-DPAT, the 5-HT-1b agonist CGS-12066B, and the 5HT-1c/2 agonist DOI did not inhibit d-amphetamine-stimulated locomotor activity. Pronounced lateral head weaving was noted after 8-OH-DPAT administration. The combination of the 5-HT-1a agonist 8-OH-DPAT and the 5-HT-1b agonist CGS-12066B, however, did inhibit d-amphetamine-stimulated locomotor activity. In contrast, the 5-HT-3 agonist 1-phenylbiguanide enhanced the locomotor effect of d-amphetamine. This effect was partially reversed by the 5-HT-3 antagonist MDL-7222. These studies suggest that serotonin has complex and multiple effects on the regulation of locomotor activity within the nucleus accumbens. 相似文献
18.
Glucocorticoid-induced gastric mucosal damage: inhibition of leukotriene, but not prostaglandin biosynthesis 总被引:9,自引:0,他引:9
J L Wallace 《Prostaglandins》1987,34(2):311-323
The effects of daily administration of ulcerogenic doses of the glucocorticoids, dexamethasone and prednisolone, on gastric prostaglandin and leukotriene synthesis were examined in the rat. Significant gastric damage was not observed until the fourth day of treatment with dexamethasone and until the sixth day of treatment with prednisolone. However, the onset of gastric damage was not accompanied by any significant effect of these drugs on gastric 6-keto prostaglandin Fl alpha synthesis. Conversely, both drugs caused a reduction in gastric leukotriene C4 synthesis, with dexamethasone producing a highly significant (p less than 0.001) effect. Furthermore, there was a highly significant (p less than 0.001) correlation between the ability of these drugs to inhibit gastric leukotriene C4 synthesis, and their ability to reduce gastric tissue levels of the neutrophilic enzyme myeloperoxidase. Thus, glucocorticoid-induced gastric damage does not appear to be related to inhibitory effects of these drugs on prostaglandin synthesis. Whether or not effects of these drugs on gastric leukotriene C4 synthesis and myeloperoxidase activity are relevant to the mechanism of ulceration is unclear. 相似文献
19.
L. L. Wallace 《Oecologia》1987,72(3):423-428
Summary A factorial design of clipping and compaction was used to study the responses of Schizachyrium scoparium and its mycorrhizal symbionts to these stresses. All treatment combinations significantly reduced the growth and biomass of plants relative to controls. Compaction significantly reduced tillering and crown expansion while clipping increased tillering early in the growing season and reduced it later. Mycorrhizal colonization of roots was highest in the clipped plots and lowest in compacted plots. Spore number was highest in compacted plots and lowest in clipped plots. It appears that spore number may be negatively correlated with root growth since any treatment that reduced plant growth yielded higher spore numbers. The combination of clipping and compaction reduced plant growth the most, but had intermediate effects on mycorrhizal colonization and spore number. 相似文献
20.
C-terminal bombesin sequence requirements for binding and effects on protein synthesis in Swiss 3T3 cells. 下载免费PDF全文
The active-site serine of the extracellular beta-lactamases of Streptomyces cacaoi and Streptomyces albus G has been labelled with beta-iodopenicillanate. The determination of the sequence of the labelled peptides obtained after trypsin digestion of the denatured proteins indicate both enzymes to be class A beta-lactamases. Surprisingly the two Streptomyces enzymes do not appear to be especially homologous, and none of them exhibited a high degree of homology with the Streptomyces R61 DD-peptidase. Our data confirm that, as a family of homologous enzymes, class A is rather heterogeneous, with only a small number of conserved residues in all members of the class. 相似文献