全文获取类型
收费全文 | 40429篇 |
免费 | 4360篇 |
国内免费 | 12篇 |
专业分类
44801篇 |
出版年
2022年 | 301篇 |
2021年 | 523篇 |
2020年 | 346篇 |
2019年 | 426篇 |
2018年 | 548篇 |
2017年 | 514篇 |
2016年 | 901篇 |
2015年 | 1624篇 |
2014年 | 1579篇 |
2013年 | 2088篇 |
2012年 | 2374篇 |
2011年 | 2096篇 |
2010年 | 1452篇 |
2009年 | 1331篇 |
2008年 | 1817篇 |
2007年 | 1791篇 |
2006年 | 1605篇 |
2005年 | 1570篇 |
2004年 | 1481篇 |
2003年 | 1276篇 |
2002年 | 1270篇 |
2001年 | 1229篇 |
2000年 | 1229篇 |
1999年 | 1103篇 |
1998年 | 606篇 |
1997年 | 563篇 |
1996年 | 556篇 |
1995年 | 536篇 |
1994年 | 489篇 |
1993年 | 513篇 |
1992年 | 1004篇 |
1991年 | 748篇 |
1990年 | 770篇 |
1989年 | 752篇 |
1988年 | 652篇 |
1987年 | 595篇 |
1986年 | 609篇 |
1985年 | 708篇 |
1984年 | 531篇 |
1983年 | 412篇 |
1982年 | 340篇 |
1981年 | 312篇 |
1980年 | 253篇 |
1979年 | 378篇 |
1978年 | 344篇 |
1977年 | 241篇 |
1976年 | 225篇 |
1975年 | 197篇 |
1974年 | 289篇 |
1973年 | 250篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
11.
Parathyrin and calcitonin stimulate cyclic AMP accumulation in cultured murine brain cells. 总被引:6,自引:0,他引:6 下载免费PDF全文
Despite the key role Ca2+ plays in the nervous system, biochemical actions on neural tissue of the Ca2+-regulating peptide hormones parathyrin and calcitonin were unknown. Until a few years ago only neurons, but not glial cells, were considered as targets for peptide hormones. Our recent observation that peptide hormones do indeed act on glial cells is extended by the present report that these cells respond to the calcaemic peptide hormones parathyrin and calcitonin. In cultured murine brain cells mainly consisting of glioblasts, parathyrin stimulates the accumulation of cyclic AMP. The half-maximal effect is elicited at 30 nM parathyrin. With rat brain cells the effects are three times those observed with mouse brain cells. Calcitonin, which is less potent than parathyrin, elevates the concentration of cyclic AMP only in rat brain cells. If properly occupied, the inhibitory receptors present on the cells lower the increase in the level of cyclic AMP evoked by parathyrin and, to some extent, that elicited by calcitonin. The results suggest that: (i) these or closely related hormones might exert regulatory functions in brain; and (ii) glial cells must be considered in discussions of the targets of the calcaemic and other peptide hormones. 相似文献
12.
M. van den Boogaard 《Marine Micropaleontology》1985,9(5):468
13.
J R van Der Ploeg R Iwanicka-Nowicka T Bykowski M M Hryniewicz T Leisinger 《The Journal of biological chemistry》1999,274(41):29358-29365
14.
15.
Carotenoids present in lipids extracted from the cyanobacterium Synechococcus 6716 indicate trans-membrane potential in proteoliposomes reconstituted from these lipids and the ATPase complex isolated from the same organism. A carotenoid absorbance band shift to a longer wavelength is obtained with valinomycin-induced potassium ion diffusion potentials, irrespective of the polarity of the potassium gradient. In contrast to this, the (externally added) probe oxonol VI only shows an absorbance band shift when the external potassium ion concentration is higher than the internal one. In liposomes without ATPase complex, no carotenoid absorbance band shifts were observed. 相似文献
16.
17.
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
18.
19.
20.
The Wageningen Delivery of Functionality symposium covered all aspects involved with food structural design to arrive at high-quality
foods which meet demanding customer expectations and regulatory requirements. The symposium integrated aspects from the structural
organization of foods at molecular and supramolecular scales to dedicated techniques required to describe and visualize such
structures, the gastro-intestinal events and how to model these in a laboratory setting, and finally the impact those food
structures and ingredients have on the consumer’s physiology and on the human perception. As an interdisciplinary platform,
bringing together more than 160 researchers from academia and industry, the symposium meanwhile fulfills an important role
in the food science community. 相似文献