全文获取类型
收费全文 | 48392篇 |
免费 | 4651篇 |
国内免费 | 27篇 |
出版年
2023年 | 212篇 |
2022年 | 501篇 |
2021年 | 1156篇 |
2020年 | 591篇 |
2019年 | 821篇 |
2018年 | 956篇 |
2017年 | 806篇 |
2016年 | 1353篇 |
2015年 | 2370篇 |
2014年 | 2468篇 |
2013年 | 2877篇 |
2012年 | 3790篇 |
2011年 | 3841篇 |
2010年 | 2345篇 |
2009年 | 2011篇 |
2008年 | 2918篇 |
2007年 | 2848篇 |
2006年 | 2691篇 |
2005年 | 2316篇 |
2004年 | 2355篇 |
2003年 | 2153篇 |
2002年 | 2056篇 |
2001年 | 578篇 |
2000年 | 434篇 |
1999年 | 489篇 |
1998年 | 491篇 |
1997年 | 378篇 |
1996年 | 353篇 |
1995年 | 312篇 |
1994年 | 277篇 |
1993年 | 283篇 |
1992年 | 304篇 |
1991年 | 326篇 |
1990年 | 276篇 |
1989年 | 283篇 |
1988年 | 244篇 |
1987年 | 227篇 |
1986年 | 221篇 |
1985年 | 297篇 |
1984年 | 273篇 |
1983年 | 242篇 |
1982年 | 276篇 |
1981年 | 300篇 |
1980年 | 242篇 |
1979年 | 201篇 |
1978年 | 166篇 |
1977年 | 166篇 |
1976年 | 167篇 |
1975年 | 147篇 |
1974年 | 169篇 |
排序方式: 共有10000条查询结果,搜索用时 672 毫秒
91.
92.
A modification of the trap assay (Woodard et al., 1989) was used to evaluate the response of Drosophila melanogaster (Meigen) to food media containing menthol. Dose-response curves for flies to mentholic foods were produced for flies that had been pre-exposed to menthol, during development and adult life, and flies that had not been exposed to menthol before the assay. Mentholic food media were less attractive to Drosophila than plain food medium. Rearing flies on a medium containing menthol reduced their aversion to some concentrations of menthol. The rearing effect was not simply due to lowered general activity levels resulting from developing in a medium containing menthol. There was a threshold concentration of menthol in the rearing medium below which we found no induced behavioural change. 相似文献
93.
Scaling of metabolic rate with body mass and temperature in teleost fish 总被引:27,自引:0,他引:27
94.
95.
Nicholas Cianciotto Terry Serwold-Davis Neal Groman Giulio Ratti Rino Rappuoli 《FEMS microbiology letters》1990,66(1-3):299-301
Chromosomal restriction fragments of Corynebacterium ulcerans and C. diphtheriae, containing an integration site for corynephages of the beta family, show homology on Southern blots. Homologous DNA in also found in the soil isolate C. glutamicum, although this strain is not susceptible to beta-corynephages. Three of these DNA fragments, one for each bacterial strain, and a fragment of gamma-corynephage DNA previously shown to contain the phage integration site, were cloned and sequenced. Alignment of the 3 bacterial sequences shows a very high degree of homology in a stretch of ca 120 nucleotides, whereas the rest of the sequences is generally non-homologous. Within this common bacterial portion, a segment of ca. 96 nucleotides (core sequence) is also highly homologous to the phage sequence. The first half (ca. 50 bp) of the core sequence is identical in all aligned sequences whereas the second half, which is largely occupied by a stem-and-loop structure, contains point mutations peculiar to each clone. The described sequences are likely to be involved in phage integration/excision processes. 相似文献
96.
97.
98.
99.
Investigation of kinase-related processes often uses pharmacological inhibition to reveal pathways in which kinases are involved. However, one concern about using such kinase inhibitors is their potential lack of specificity. Here, we report that the calcium–calmodulin-dependent kinase II (CaMKII) inhibitor CK59 inhibited multiple voltage-gated calcium channels, including the L-type channel during depolarization in a dose-dependent manner. The use of another CaMKII inhibitor, cell-permeable autocamtide-2 related inhibitory peptide II (Ant-AIP-II), failed to similarly decrease calcium current or entry in hippocampal cultures, as shown by ratiometric calcium imaging and whole-cell patch clamp electrophysiology. Notably, inhibition due to CK59 was reversible; washout of the drug brought calcium levels back to control values upon depolarization. Furthermore, the IC50 for CK59 was approximately 50 μM, which is only fivefold larger than the reported IC50 values for CaMKII inhibition. Similar nonspecific actions of other CaMKII inhibitors KN93 and KN62 have previously been reported. In the case of all three kinase inhibitors, the IC50 for calcium current inhibition falls near that of CaMKII inhibition. Our findings demonstrate that CK59 attenuates activity of voltage-gated calcium channels, and thus provide more evidence for caution when relying on pharmacological inhibition to examine kinase-dependent phenomena. 相似文献
100.
Comparative phylogeography of two co‐distributed but ecologically distinct rainbowfishes of far‐northern Australia 下载免费PDF全文
Andrew T. Mather Jeffrey O. Hanson Lisa C. Pope Cynthia Riginos 《Journal of Biogeography》2018,45(1):127-141