全文获取类型
收费全文 | 498篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
系统科学 | 3篇 |
丛书文集 | 2篇 |
教育与普及 | 3篇 |
理论与方法论 | 2篇 |
现状及发展 | 87篇 |
研究方法 | 42篇 |
综合类 | 358篇 |
自然研究 | 3篇 |
出版年
2018年 | 2篇 |
2017年 | 6篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2012年 | 33篇 |
2011年 | 67篇 |
2010年 | 23篇 |
2009年 | 5篇 |
2008年 | 23篇 |
2007年 | 28篇 |
2006年 | 23篇 |
2005年 | 21篇 |
2004年 | 20篇 |
2003年 | 18篇 |
2002年 | 18篇 |
2001年 | 10篇 |
2000年 | 14篇 |
1999年 | 18篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 2篇 |
1992年 | 3篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1974年 | 11篇 |
1972年 | 4篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 3篇 |
1965年 | 1篇 |
1964年 | 2篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1946年 | 1篇 |
排序方式: 共有500条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
A keratin cytoskeletal protein regulates protein synthesis and epithelial cell growth 总被引:1,自引:0,他引:1
Cell growth, an increase in mass and size, is a highly regulated cellular event. The Akt/mTOR (mammalian target of rapamycin) signalling pathway has a central role in the control of protein synthesis and thus the growth of cells, tissues and organisms. A striking example of a physiological context requiring rapid cell growth is tissue repair in response to injury. Here we show that keratin 17, an intermediate filament protein rapidly induced in wounded stratified epithelia, regulates cell growth through binding to the adaptor protein 14-3-3sigma. Mouse skin keratinocytes lacking keratin 17 (ref. 4) show depressed protein translation and are of smaller size, correlating with decreased Akt/mTOR signalling activity. Other signalling kinases have normal activity, pointing to the specificity of this defect. Two amino acid residues located in the amino-terminal head domain of keratin 17 are required for the serum-dependent relocalization of 14-3-3sigma from the nucleus to the cytoplasm, and for the concomitant stimulation of mTOR activity and cell growth. These findings reveal a new and unexpected role for the intermediate filament cytoskeleton in influencing cell growth and size by regulating protein synthesis. 相似文献
95.
The separation of the effects of environmental variability from the impacts of fishing has been elusive, but is essential for sound fisheries management. We distinguish environmental effects from fishing effects by comparing the temporal variability of exploited versus unexploited fish stocks living in the same environments. Using the unique suite of 50-year-long larval fish surveys from the California Cooperative Oceanic Fisheries Investigations we analyse fishing as a treatment effect in a long-term ecological experiment. Here we present evidence from the marine environment that exploited species exhibit higher temporal variability in abundance than unexploited species. This remains true after accounting for life-history effects, abundance, ecological traits and phylogeny. The increased variability of exploited populations is probably caused by fishery-induced truncation of the age structure, which reduces the capacity of populations to buffer environmental events. Therefore, to avoid collapse, fisheries must be managed not only to sustain the total viable biomass but also to prevent the significant truncation of age structure. The double jeopardy of fishing to potentially deplete stock sizes and, more immediately, to amplify the peaks and valleys of population variability, calls for a precautionary management approach. 相似文献
96.
This paper evaluates the comfort properties of eightkinds of woven fabric commonly used for children'ssummer wear in Hong Kong,China.Due to the expan-sion of children's wear market and the quality require-ment for parents,objective and subjective measurementsare the main methods used to evaluate the chosen fabricsfor garment deslgners and consumers as reference. Objective measurement was carried out through ex-periments by means of the Kawabata Evaluation Systemfor Fabrics(KES-F).Experimental tests on fabrics in-clude compression,surface,bending,air permeability,thermal and tensile.Subjective measurement was con-ducted by a market research on consumers' opinions onfabrics for children's summer wear in the form of ques-tionnaire survey.These two ways of measurement onfabrics were analyzed and compared. It was found that Fabric Sample 6 which is com-posed of polyester and cotton fibre has the best perfor-mance in terms of its comfort properties.Besides,Sam-ple 4 composes of rayon and cotton fibre also ha 相似文献
97.
<正>本设计为二窑一套的干燥工段定型设计。窑主体采用钢筋混疑土内壳,能有效地抗腐蚀、风化和开裂。采用双层单扇金属保温门,开关轻便可靠,并装有膨胀式气密垫圈,可确保门的上沿和两侧完全不漏气,还设有含水率测量装置和观察窗,可在操作间监测干燥过程中的试材含水率变化,并可随时看到材堆端头有、无开裂发生。 该窑可实施常规、高温或过热蒸汽干燥,干燥性能和节能效果较好。 相似文献
98.
This paper studies on fabrics suitable for child patients'garment in the hospital environment in Hong Kong,China.Subjective measurement was carried out by questionnaire survey to consult medical staff on hospital requirement about fabric criteria for child patients' garment. On the other hand, objective measurement was conducted by performing laboratory tests on fabrics,which were sourced from commercial fabric market. Both measurements are evaluated according to the results on those fabric criteria in order to determine the most suitable kind of fabric for the end purpose. As a result of the comparison, it was found that T/C 1 scores the highest index. Therefore, it will be suggested for manufacturing child patients' garment to evaluate the fabric suitability to meet the wearers' requirement through hospital trial. 相似文献
99.
Several prominent voices have called for a democratization of science through deliberative processes that include a diverse range of perspectives and values. We bring these scholars into conversation with extant research on democratic deliberation in political theory and the social sciences. In doing so, we identify systematic barriers to the effectiveness of inclusive deliberation in both scientific and political settings. We are particularly interested in what we call misidentified dissent, where deliberations are starkly framed at the outset in terms of dissenting positions without properly distinguishing the kinds of difference and disagreement motivating dissent. 相似文献
100.