全文获取类型
收费全文 | 33660篇 |
免费 | 84篇 |
国内免费 | 95篇 |
专业分类
系统科学 | 287篇 |
丛书文集 | 652篇 |
教育与普及 | 76篇 |
理论与方法论 | 125篇 |
现状及发展 | 14417篇 |
研究方法 | 1338篇 |
综合类 | 16333篇 |
自然研究 | 611篇 |
出版年
2013年 | 208篇 |
2012年 | 461篇 |
2011年 | 1076篇 |
2010年 | 189篇 |
2008年 | 573篇 |
2007年 | 596篇 |
2006年 | 626篇 |
2005年 | 625篇 |
2004年 | 621篇 |
2003年 | 596篇 |
2002年 | 508篇 |
2001年 | 997篇 |
2000年 | 965篇 |
1999年 | 608篇 |
1992年 | 586篇 |
1991年 | 485篇 |
1990年 | 526篇 |
1989年 | 469篇 |
1988年 | 511篇 |
1987年 | 503篇 |
1986年 | 476篇 |
1985年 | 673篇 |
1984年 | 506篇 |
1983年 | 415篇 |
1982年 | 364篇 |
1981年 | 376篇 |
1980年 | 482篇 |
1979年 | 1000篇 |
1978年 | 816篇 |
1977年 | 788篇 |
1976年 | 691篇 |
1975年 | 775篇 |
1974年 | 949篇 |
1973年 | 865篇 |
1972年 | 879篇 |
1971年 | 1049篇 |
1970年 | 1326篇 |
1969年 | 1085篇 |
1968年 | 992篇 |
1967年 | 977篇 |
1966年 | 889篇 |
1965年 | 660篇 |
1964年 | 187篇 |
1959年 | 400篇 |
1958年 | 658篇 |
1957年 | 463篇 |
1956年 | 430篇 |
1955年 | 357篇 |
1954年 | 419篇 |
1948年 | 290篇 |
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
21.
Lindahl E Nyman U Melles E Sigmundsson K Ståhlberg M Wahren J Obrink B Shafqat J Joseph B Jörnvall H 《Cellular and molecular life sciences : CMLS》2007,64(4):479-486
Proinsulin C-peptide is known to bind specifically to cell membranes and to exert intracellular effects, but whether it is
internalized in target cells is unknown. In this study, using confocal microscopy and immunostained or rhodamine-labeled peptide,
we show that C-peptide is internalized and localized to the cytosol of Swiss 3T3 and HEK-293 cells. In addition, transport
into nuclei was found using the labeled peptide. The internalization was followed at 37°C for up to 1 h, and was reduced at
4°C and after preincubation with pertussis toxin. Hence, it is concluded to occur via an energy-dependent, pertussis toxin-sensitive
mechanism and without detectable degradation within the experimental time course. Surface plasmon resonance measurements demonstrated
binding of HEK-293 cell extract components to C-peptide, and subsequent elution of bound material revealed the components
to be intracellular proteins. The identification of C-peptide cellular internalization, intracellular binding proteins, absence
of rapid subsequent C-peptide degradation and apparent nuclear internalization support a maintained activity similar to that
of an intracrine peptide hormone. Hence, the data suggest the possibility of one further C-peptide site of action.
Received 31 October 2006; received after revision 27 December 2006; accepted 30 December 2006 相似文献
22.
1 Results Acid-doped polybenzimidazoles[1] are particularly appealing because of high proton conductivity with no or low humidification and promising fuel cells performances. PBI, in fact, contains basic functional groups which can easily interact with strong oxo-acids, such as H3PO4 and H2SO4. The acid partially protonates the polymer and partially is freely dispersed in the polymer backbone, so allowing proton migration via Grotthuss mechanism along the anionic chains[2]. Anyway, a technological limit... 相似文献
23.
Advances in our understanding of cardiac development have fuelled research into cellular approaches to myocardial repair of
the damaged heart. In this collection of reviews we present recent advances into the basic mechanisms of heart development
and the resident and non-resident progenitor cell populations that are currently being investigated as potential mediators
of cardiac repair. Together these reviews illustrate that despite our current knowledge about how the heart is constructed,
caution and much more research in this exciting field is essential. The current momentum to evaluate the potential for cardiac
repair will in turn accelerate research into fundamental aspects of myocardial biology. 相似文献
24.
Summary Intravenous or subcutaneous administration of pyribenzamine and other antihistaminics is able to decrease, and to delay the appearance of chemosis produced by mustard oils in the eye of the rabbit. Simultaneously occurring vascular reactions, on the other hand, are but slightly affected by antihistaminics. Intravenous or subcutaneous administration of rutin has no clear-cut effect on chemosis; it is however able to inhibit the vascular reaction. 相似文献
25.
26.
27.
28.
29.
30.