全文获取类型
收费全文 | 1349篇 |
免费 | 92篇 |
国内免费 | 1篇 |
专业分类
1442篇 |
出版年
2015年 | 27篇 |
2014年 | 25篇 |
2013年 | 29篇 |
2012年 | 32篇 |
2011年 | 33篇 |
2010年 | 40篇 |
2009年 | 39篇 |
2008年 | 48篇 |
2007年 | 66篇 |
2006年 | 42篇 |
2005年 | 42篇 |
2004年 | 32篇 |
2003年 | 25篇 |
2002年 | 26篇 |
2001年 | 23篇 |
2000年 | 19篇 |
1999年 | 21篇 |
1998年 | 16篇 |
1997年 | 21篇 |
1996年 | 18篇 |
1995年 | 19篇 |
1994年 | 14篇 |
1993年 | 20篇 |
1992年 | 19篇 |
1991年 | 27篇 |
1990年 | 21篇 |
1989年 | 18篇 |
1988年 | 21篇 |
1987年 | 27篇 |
1986年 | 20篇 |
1985年 | 22篇 |
1984年 | 21篇 |
1982年 | 23篇 |
1980年 | 16篇 |
1979年 | 16篇 |
1977年 | 14篇 |
1976年 | 21篇 |
1974年 | 20篇 |
1973年 | 22篇 |
1972年 | 18篇 |
1971年 | 16篇 |
1968年 | 13篇 |
1965年 | 39篇 |
1964年 | 21篇 |
1963年 | 32篇 |
1962年 | 23篇 |
1961年 | 35篇 |
1960年 | 21篇 |
1959年 | 28篇 |
1958年 | 27篇 |
排序方式: 共有1442条查询结果,搜索用时 0 毫秒
51.
An Ethnographic Filmflam: Giving Gifts, Doing Research, and Videotaping the Native Subject/Object 总被引:1,自引:0,他引:1
JOHN L. JACKSON JR. 《American anthropologist》2004,106(1):32-42
Using the discussion of self-reflexivity as an organizing principle, this article examines how mobilizing digital video technology during fieldwork opens up empirical and theoretical space for reconceptualizing the relationship between anthropologists and informants. Placing the field of visual anthropology into critical conversation with long-standing theoretical arguments about the objectivist limitations of native anthropologists, I argue that the slipperiness of nativity as an anthropological designation helps to provide analytical tools for examining filmmaking as a kind of gift-giving process between native ethnographic filmmakers and the subjects of their films. This article highlights some of the ways in which my own filmic and videographic exploits in Harlem, New York, mark integral connections between seeing and being the proverbial other, probing social exchanges predicated on the usefulness of low-budget digital technology as a means of fostering politically and epistemologically valuable ethnographic collaborations. 相似文献
52.
Regression analysis based on stratified samples 总被引:1,自引:0,他引:1
53.
Onoclea sensibilis gametophytes were grown from spores on ashedsoil and agar to determine if the spontaneous formation of antheridiacan be blocked by light. Under most conditions, dark-grown gametophytesformed antheridia later than or at the same time as gametophytesgrown in the light. Under no circumstances was there a rapidonset of maleness in the dark. These results contradict thehypothesis that, in Onoclea, antheridiogen is required to inducemaleness because light inhibits the formation of antheridia.In the light, antheridia formed on heart-shaped thalli. In darkness,antheridia formed on filamentous gametophytes. The timing ofonset of maleness was affected by temperature and the presenceof sucrose. The effect of sucrose on the comparison betweenlight and dark treatments depended on both substrate and temperature Onoclea sensibilis, L., sensitive fern, fern gametophytes, sexuality, light-induced block 相似文献
54.
Dissociated cells of the R3230AC mammary tumor were found to take up glucose by diffusion and by a passive carrier system. Using labeled 3-O-methylglucose as the probe, the following properties of the passive carrier were identified: (1) specificity for glucose, (2) competition by galactose and mannose but not by mannitol and fructose, (3) inhibition by phloretin but not by phloridzin, (4) temperature sensitivity, and (5) a Km for transport of 3-4 mM. The effects of insulin in vitro on carrier-mediated glucose transport were investigated in tumor cells from diabetic rats. At 10-9 M insulin, a time-related decrease in v for transport was observed resulting in an increased calculated Km (2- to 3-fold increase after 60-90 min incubation with insulin); only slight effects on V were obtained. This unusual response in v to insulin was observed when glucose was present in the medium at 2 mM and 5 mM, but not at 20 mM glucose. The effect of insulin to decrease the v was dose-related, with the major effects seen between 10-10M and 10-8M. The apparent decrease in glucose entry in vitro may in part explain the ability of insulin to inhibit growth of this tumor in vivo. 相似文献
55.
Hanneke Vlaming Tibor van Welsem Erik L de Graaf David Ontoso AF Maarten Altelaar Pedro A San-Segundo Albert JR Heck Fred van Leeuwen 《EMBO reports》2014,15(10):1077-1084
Histone H2B ubiquitination is a dynamic modification that promotes methylation of histone H3K79 and H3K4. This crosstalk is important for the DNA damage response and has been implicated in cancer. Here, we show that in engineered yeast strains, ubiquitins tethered to every nucleosome promote H3K79 and H3K4 methylation from a proximal as well as a more distal site, but only if in a correct orientation. This plasticity indicates that the exact location of the attachment site, the native ubiquitin-lysine linkage and ubiquitination cycles are not critical for trans-histone crosstalk in vivo. The flexibility in crosstalk also indicates that other ubiquitination events may promote H3 methylation. 相似文献
56.
57.
58.
Although the glycogen content of mouse tail skin was decreased during starvation and was restored on re feeding, the proportion of glycogen synthase in the I form remained constant throughout at about 10% of the total. During the phase of net glycogen synthesis 1.5h after access to food was restored, the concentration of UDP glucose was markedly increased and the proportion of phosphorylase in the a form was significantly decreased. 相似文献
59.
60.