全文获取类型
收费全文 | 2735篇 |
免费 | 14篇 |
国内免费 | 41篇 |
专业分类
系统科学 | 65篇 |
丛书文集 | 15篇 |
教育与普及 | 4篇 |
理论与方法论 | 53篇 |
现状及发展 | 953篇 |
研究方法 | 310篇 |
综合类 | 1302篇 |
自然研究 | 88篇 |
出版年
2019年 | 15篇 |
2018年 | 31篇 |
2017年 | 31篇 |
2016年 | 27篇 |
2015年 | 26篇 |
2014年 | 31篇 |
2013年 | 48篇 |
2012年 | 161篇 |
2011年 | 232篇 |
2010年 | 59篇 |
2009年 | 18篇 |
2008年 | 129篇 |
2007年 | 128篇 |
2006年 | 122篇 |
2005年 | 112篇 |
2004年 | 106篇 |
2003年 | 130篇 |
2002年 | 171篇 |
2001年 | 144篇 |
2000年 | 99篇 |
1999年 | 67篇 |
1997年 | 11篇 |
1992年 | 25篇 |
1990年 | 18篇 |
1989年 | 16篇 |
1988年 | 22篇 |
1987年 | 27篇 |
1986年 | 26篇 |
1985年 | 22篇 |
1984年 | 21篇 |
1983年 | 18篇 |
1982年 | 15篇 |
1981年 | 15篇 |
1980年 | 26篇 |
1979年 | 41篇 |
1978年 | 37篇 |
1977年 | 35篇 |
1976年 | 30篇 |
1975年 | 37篇 |
1974年 | 32篇 |
1973年 | 34篇 |
1972年 | 45篇 |
1971年 | 43篇 |
1970年 | 36篇 |
1969年 | 32篇 |
1968年 | 24篇 |
1967年 | 31篇 |
1966年 | 34篇 |
1965年 | 21篇 |
1958年 | 9篇 |
排序方式: 共有2790条查询结果,搜索用时 31 毫秒
101.
Inflammasomes: current understanding and open questions 总被引:2,自引:2,他引:0
Bauernfeind F Ablasser A Bartok E Kim S Schmid-Burgk J Cavlar T Hornung V 《Cellular and molecular life sciences : CMLS》2011,68(5):765-783
The innate immune system relies on its capability to detect invading microbes, tissue damage, or stress via evolutionarily
conserved receptors. The nucleotide-binding domain leucine-rich repeat (NLR)-containing family of pattern recognition receptors
includes several proteins that drive inflammation in response to a wide variety of molecular patterns. In particular, the
NLRs that participate in the formation of a molecular scaffold termed the “inflammasome” have been intensively studied in
past years. Inflammasome activation by multiple types of tissue damage or by pathogen-associated signatures results in the
autocatalytic cleavage of caspase-1 and ultimately leads to the processing and thus secretion of pro-inflammatory cytokines,
most importantly interleukin (IL)-1β and IL-18. Here, we review the current knowledge of mechanisms leading to the activation
of inflammasomes. In particular, we focus on the controversial molecular mechanisms that regulate NLRP3 signaling and highlight
recent advancements in DNA sensing by the inflammasome receptor AIM2. 相似文献
102.
Amiot L Ferrone S Grosse-Wilde H Seliger B 《Cellular and molecular life sciences : CMLS》2011,68(3):417-431
Although the expression of the non-classical HLA class I molecule HLA-G was first reported to be restricted to the fetal–maternal
interface on the extravillous cytotrophoblasts, the distribution of HLA-G in normal tissues appears broader than originally
described. HLA-G expression was found in embryonic tissues, in adult immune privileged organs, and in cells of the hematopoietic
lineage. More interestingly, under pathophysiological conditions HLA-G antigens may be expressed on various types of malignant
cells suggesting that HLA-G antigen expression is one strategy used by tumor cells to escape immune surveillance. In this
article, we will focus on HLA-G expression in cancers of distinct histology and its association with the clinical course of
diseases, on the underlying molecular mechanisms of impaired HLA-G expression, on the immune tolerant function of HLA-G in
tumors, and on the use of membrane-bound and soluble HLA-G as a diagnostic or prognostic biomarker to identify tumors and
to monitor disease stage, as well as on the use of HLA-G as a novel therapeutic target in cancer. 相似文献
103.
Banson Kwamina Ewur Asare Daniel Kwasi Dery Fidelis Doodaa Boakye Kwadwo Boniface Akudugu Asamoah Moses Awotwe Lourees Esi 《Systemic Practice and Action Research》2020,33(2):237-264
Systemic Practice and Action Research - Fall armyworm (FAW) infestation in African countries presents significant threats to maize production. Such infestation has major economic implications in... 相似文献
104.
数据挖掘分类问题的贪婪粗糙集约简算法 总被引:7,自引:0,他引:7
基于贪婪算法和粗糙集方法,给出了一种处理数据挖掘分类问题的属性约简算法:贪婪粗糙集约简算法GRSR;在测试中得出的约简集为原始集的1/3,表明了它是一个有效的算法·其想法是:从初始约简集为空集开始,选择使分类质量最大的属性,将它加入约简集;再从余下的属性中选择使分类质量最大的属性并加入约简集,重复直至找到满意的约简集· 相似文献
105.
Modulation of ion channels is of increasing interest as it is an important step in the regulation of cellular functions. We have analysed the effect of 8-bromocyclic AMP on Ca2+ channels in cultured cardiac cells by the patch-clamp method and report here that there was a large increase in the probability of opening of the channels. On the basis of a recently proposed kinetic reaction scheme we suggest that cyclic AMP-dependent phosphorylation of Ca2+ channels primarily promotes the forward rate constants which lead to the open state of a Ca2+ channel during depolarization. 相似文献
106.
合成了一个三齿配体,并对其抗肿瘤活性进行了测试. 相似文献
107.
连续梁桥的减隔震设计 总被引:6,自引:0,他引:6
在对桥梁减隔震原理进行分析的基础上,依据连续梁桥在地震作用时受力的特点,对连续桥梁的固定支座进行了减隔震设计,将原来的固定支座改为相对固定.对该桥在地震荷载作用下的抗震性能分析表明,采取减隔震措施后,固定墩的受力情况得到明显改善,主梁的纵向位移以及梁、墩的相对位移虽有所增大,但即使在8°的地震荷载作用下,位移幅度仍在支座允许的位移范围内. 相似文献
108.
Metagenomic and functional analysis of hindgut microbiota of a wood-feeding higher termite 总被引:6,自引:0,他引:6
Warnecke F Luginbühl P Ivanova N Ghassemian M Richardson TH Stege JT Cayouette M McHardy AC Djordjevic G Aboushadi N Sorek R Tringe SG Podar M Martin HG Kunin V Dalevi D Madejska J Kirton E Platt D Szeto E Salamov A Barry K Mikhailova N Kyrpides NC Matson EG Ottesen EA Zhang X Hernández M Murillo C Acosta LG Rigoutsos I Tamayo G Green BD Chang C Rubin EM Mathur EJ Robertson DE Hugenholtz P Leadbetter JR 《Nature》2007,450(7169):560-565
From the standpoints of both basic research and biotechnology, there is considerable interest in reaching a clearer understanding of the diversity of biological mechanisms employed during lignocellulose degradation. Globally, termites are an extremely successful group of wood-degrading organisms and are therefore important both for their roles in carbon turnover in the environment and as potential sources of biochemical catalysts for efforts aimed at converting wood into biofuels. Only recently have data supported any direct role for the symbiotic bacteria in the gut of the termite in cellulose and xylan hydrolysis. Here we use a metagenomic analysis of the bacterial community resident in the hindgut paunch of a wood-feeding 'higher' Nasutitermes species (which do not contain cellulose-fermenting protozoa) to show the presence of a large, diverse set of bacterial genes for cellulose and xylan hydrolysis. Many of these genes were expressed in vivo or had cellulase activity in vitro, and further analyses implicate spirochete and fibrobacter species in gut lignocellulose degradation. New insights into other important symbiotic functions including H2 metabolism, CO2-reductive acetogenesis and N2 fixation are also provided by this first system-wide gene analysis of a microbial community specialized towards plant lignocellulose degradation. Our results underscore how complex even a 1-microl environment can be. 相似文献
109.
110.
New use of BCG for recombinant vaccines 总被引:147,自引:0,他引:147
C K Stover V F de la Cruz T R Fuerst J E Burlein L A Benson L T Bennett G P Bansal J F Young M H Lee G F Hatfull 《Nature》1991,351(6326):456-460
BCG, a live attenuated tubercle bacillus, is the most widely used vaccine in the world and is also a useful vaccine vehicle for delivering protective antigens of multiple pathogens. Extrachromosomal and integrative expression vectors carrying the regulatory sequences for major BCG heat-shock proteins have been developed to allow expression of foreign antigens in BCG. These recombinant BCG strains can elicit long-lasting humoral and cellular immune responses to foreign antigens in mice. 相似文献