全文获取类型
收费全文 | 92700篇 |
免费 | 8111篇 |
国内免费 | 54篇 |
出版年
2023年 | 447篇 |
2022年 | 437篇 |
2021年 | 2041篇 |
2020年 | 1361篇 |
2019年 | 1605篇 |
2018年 | 2110篇 |
2017年 | 1774篇 |
2016年 | 2824篇 |
2015年 | 4313篇 |
2014年 | 4499篇 |
2013年 | 5209篇 |
2012年 | 6694篇 |
2011年 | 6143篇 |
2010年 | 3844篇 |
2009年 | 3524篇 |
2008年 | 4680篇 |
2007年 | 4601篇 |
2006年 | 4183篇 |
2005年 | 4353篇 |
2004年 | 4189篇 |
2003年 | 3695篇 |
2002年 | 3190篇 |
2001年 | 1821篇 |
2000年 | 1640篇 |
1999年 | 1594篇 |
1998年 | 985篇 |
1997年 | 818篇 |
1996年 | 785篇 |
1995年 | 668篇 |
1994年 | 688篇 |
1993年 | 655篇 |
1992年 | 1156篇 |
1991年 | 1044篇 |
1990年 | 964篇 |
1989年 | 935篇 |
1988年 | 935篇 |
1987年 | 850篇 |
1986年 | 779篇 |
1985年 | 756篇 |
1984年 | 745篇 |
1983年 | 567篇 |
1982年 | 495篇 |
1981年 | 483篇 |
1980年 | 449篇 |
1979年 | 544篇 |
1978年 | 471篇 |
1977年 | 397篇 |
1975年 | 370篇 |
1974年 | 372篇 |
1973年 | 385篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
21.
Morphological taxonomy of simple Hyphomycetes is complicated by the frequent occurrence of pleoanamorphism. In some groups
of yeast-like fungi, uncommon synanamorphs are diagnostic. Differences in conidiogenesis do not always delimit natural groups.
Some nomenclatural problems are mentioned, with an emphasis on the need of neotypification. Prospects are sketched for future
taxonomic research. 相似文献
22.
C Chong-Cerrillo M E Selsted E M Peterson L M de la Maza 《The journal of peptide research》2003,61(5):237-242
Four antimicrobial peptides, protegrin-1, RTD-1, cryptdin-4, and indolicidin, were tested for their ability to inhibit the in vitro growth of Chlamydia trachomatis serovars E, L2, and mouse pneumonitis (MoPn). In general, protegrin-1 was found to have the strongest anti-chlamydial activity. Overall, of the three serovars tested, L2 was the most susceptible while MoPn was the most resistant to these peptides. 相似文献
23.
24.
25.
M. de Kwaadsteniet C. A. van Reenen L. M. T. Dicks 《Probiotics and antimicrobial proteins》2010,2(2):61-65
The potential of nisin F as an antimicrobial agent in treating subcutaneous skin infections was tested in vivo by infecting C57BL/6 mice with a bioluminescent strain of Staphylococcus aureus (Xen 36). Strain Xen 36 has the luxABCDE operon located on a native plasmid. Mice were grouped into four groups: Infected with strain Xen 36 and treated with nisin F, infected with strain Xen 36 and treated with saline (placebo), not infected and treated with nisin (control) and not infected and not treated (control). The immune systems of the mice were suppressed with deksamethasone. Mice were treated with either nisin F or sterile physiological saline 24 and 48 h after infection with subcutaneously injected S. aureus Xen 36 (4 × 106 CFU). Histology and bioluminescent flux measurements revealed no significant difference between infected mice treated with nisin and saline, respectively. However, infected mice treated with nisin F had an increased number of polymorphonuclear cells when compared with infected mice treated with saline. Also, not infected mice treated with nisin F had an influx of polymorphonuclear cells. Nisin F is thus ineffective in combating deep dermal staphylococcal infections. The apparent immune modulation of nisin when subcutaneously injected has to be investigated. 相似文献
26.
Elizabeth Storer Scholl Antonella Pirone Daniel H Cox R Keith Duncan Michele H Jacob 《Channels (Austin, Tex.)》2014,8(1):62-75
Small conductance Ca2+-sensitive potassium (SK2) channels are voltage-independent, Ca2+-activated ion channels that conduct potassium cations and thereby modulate the intrinsic excitability and synaptic transmission of neurons and sensory hair cells. In the cochlea, SK2 channels are functionally coupled to the highly Ca2+ permeant α9/10-nicotinic acetylcholine receptors (nAChRs) at olivocochlear postsynaptic sites. SK2 activation leads to outer hair cell hyperpolarization and frequency-selective suppression of afferent sound transmission. These inhibitory responses are essential for normal regulation of sound sensitivity, frequency selectivity, and suppression of background noise. However, little is known about the molecular interactions of these key functional channels. Here we show that SK2 channels co-precipitate with α9/10-nAChRs and with the actin-binding protein α-actinin-1. SK2 alternative splicing, resulting in a 3 amino acid insertion in the intracellular 3′ terminus, modulates these interactions. Further, relative abundance of the SK2 splice variants changes during developmental stages of synapse maturation in both the avian cochlea and the mammalian forebrain. Using heterologous cell expression to separately study the 2 distinct isoforms, we show that the variants differ in protein interactions and surface expression levels, and that Ca2+ and Ca2+-bound calmodulin differentially regulate their protein interactions. Our findings suggest that the SK2 isoforms may be distinctly modulated by activity-induced Ca2+ influx. Alternative splicing of SK2 may serve as a novel mechanism to differentially regulate the maturation and function of olivocochlear and neuronal synapses. 相似文献
27.
Transcriptional regulatory network triggered by oxidative signals configures the early response mechanisms of japonica rice to chilling stress 总被引:3,自引:0,他引:3
28.
A review of in vitro mutagenesis assessment of metal compounds in mammalian and nonmammalian test systems has been compiled.
Prokaryotic assays are ineffective or inconsistent in their detection of most metals as mutagens, with the notable exception
of hexavalent chromium. Mammalian assay systems appear to be similarly inappropriate for the screening of metal compounds
based upon the limited number of studies that have employed those compounds having known carcinogenic activity. Although of
limited value as screening tests for the detection of potentially carcinogenic metal compounds, the well-characterized in
vitro mutagenesis systems may prove to be of significant value as a means to elucidate mechanisms of metal genotoxicity. 相似文献
29.
L V Melendez M D Daniel H H Barahona C E Fraser R D Hunt F G Garcia 《Laboratory animal science》1971,21(6):1050-1054
30.