全文获取类型
收费全文 | 633篇 |
免费 | 32篇 |
国内免费 | 4篇 |
专业分类
669篇 |
出版年
2022年 | 8篇 |
2021年 | 11篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 18篇 |
2016年 | 14篇 |
2015年 | 32篇 |
2014年 | 43篇 |
2013年 | 39篇 |
2012年 | 63篇 |
2011年 | 63篇 |
2010年 | 42篇 |
2009年 | 28篇 |
2008年 | 33篇 |
2007年 | 27篇 |
2006年 | 30篇 |
2005年 | 30篇 |
2004年 | 18篇 |
2003年 | 19篇 |
2002年 | 16篇 |
2001年 | 17篇 |
2000年 | 11篇 |
1999年 | 16篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1965年 | 1篇 |
1959年 | 1篇 |
1958年 | 1篇 |
1957年 | 3篇 |
1956年 | 1篇 |
1955年 | 3篇 |
1954年 | 1篇 |
1951年 | 1篇 |
1950年 | 1篇 |
1949年 | 1篇 |
排序方式: 共有669条查询结果,搜索用时 15 毫秒
1.
2.
SHINSAKU TAKAYAMA MASANARU MISAWA KEIDO KO TOMOMASA MISATO 《Physiologia plantarum》1977,41(4):313-320
An extract of cultured Agroxieinma githago L. cells was found to show potent inhibitory activity against plans virus infection. The effects of cultural conditions on the growth of the cell suspension and on the production of the inhibitor were examined. Since the production of substance was dependent on growth. experiments were made to improve growth. The optimum temperature was 26 to 30°C and optimum pH of the medium before autoclaving was between 5 and 7. In a medium of higher osmotic pressure, the water content of the cultured cells was lowered markedly. The growth rate in a small volume of the medium was higher than that in a larger volume at an early stage of the cultivation, but it was not changed by different inoculum sizes. The cells required thiamine and 2,4-D for growth but no other vitamins or growth regulators. The optimum level of 2,4-D was 0.1 mg/l. Higher sucrose concentration in the medium gave higher production of cell mass and of the inhibitor. However, 3% of sucrose was selected as the most economical concentration. For normal cell growth, the presence of both NH4NO3 and KNO3 as nitrogen sources was required. The use of a single nitrogen source caused a long lag period or inhibition of the cell growth. KH2PO4 stimulated the growth when in was used in the level of 2.5 to 5 mM. The cell adhesion on the surface of the fermentor sometimes causes trouble in a large-scale cultivation. It was found that reducing the Ca2+ level in the medium prevented the cell adhesion and foaming remarkably. Based on the results obtained, a modified medium was established which was excellent for shortening the culture period and for efficient production of the anti-plant virus inhibitor. 相似文献
3.
4.
5.
Eui-Baek Byun Woo-Young Park Woo Sik Kim Ha-Yeon Song Nak-Yun Sung 《Bioscience, biotechnology, and biochemistry》2013,77(12):2149-2157
ABSTRACTPhenolic compounds isolated from pepper (Capsicum annum) have been demonstrated to have neuroprotective effects, whereas the physiological properties of Capsicum annuum var. abbreviatum (CAA) have not been studied. Thus, we investigate the chemical composition and neuroprotective activity of CAA extract (CAAE) in HT22 hippocampus cells against H2O2-induced neurotoxicity. CAAE treatment resulted in a significant protection of H2O2-exposed HT22, this protection ultimately occurred through an inhibition of MDA and ROS levels and an induction of SOD activity. Furthermore, CAAE treatment reduced H202-induced apoptosis though decreasing the expression of pro-apoptotic factors (Bax, cytochrome c, and cleaved caspases-3) while increasing the expression of the anti-apoptotic factors (Bcl-2), as well as the accumulation of nucleus-Nrf2-mediated HO-1 signaling. Interestingly, CAAE has a high concentration of unique phenolic compositions (chlrogenic acid, tangeretin, etc.) than other capsicum annum extracts. Altogether, these findings suggest that CAAE can be a useful natural resource for alleviating neurodegenerative diseases. 相似文献
6.
7.
H S Cheong J S Chang J M Park S M Byun 《Biochemical and biophysical research communications》1990,173(3):795-800
For the enhancement of antibody binding affinity, a bispecific antibody against two different epitopes in human chorionic gonadotropin hormone, one is in alpha-subunit and the other is in beta-subunit, was prepared by chemical recombination using 5,5'-dithiobis(2-nitrobenzoic acid). The epitopes recognized by antibodies were investigated by competitive radioimmunoassay, two-site sandwich radioimmunoassay and additivity assay and a proper epitope pair was chosen for preparation of the bispecific antibody. This bispecific antibody has dual specificity and as much as 17.2-fold higher affinity than that of monoclonal antibody with higher affinity by dual antigen binding radioimmunoassay and Scatchard plot analysis. 相似文献
8.
9.
10.
Slit molecules comprise one of the four canonical families of axon guidance cues that steer the growth cone in the developing nervous system. Apart from their role in axon pathfinding, emerging lines of evidence suggest that a wide range of cellular processes are regulated by Slit, ranging from branch formation and fasciculation during neurite outgrowth to tumor progression and to angiogenesis. However, the molecular and cellular mechanisms downstream of Slit remain largely unknown, in part, because of a lack of a readily manipulatable system that produces easily identifiable traits in response to Slit. The present study demonstrates the feasibility of using the cell line CAD as an assay system to dissect the signaling pathways triggered by Slit. Here, we show that CAD cells express receptors for Slit (Robo1 and Robo2) and that CAD cells respond to nanomolar concentrations of Slit2 by markedly decelerating the rate of process extension. Using this system, we reveal that Slit2 inactivates GSK3β and that inhibition of GSK3β is required for Slit2 to inhibit process outgrowth. Furthermore, we show that Slit2 induces GSK3β phosphorylation and inhibits neurite outgrowth in adult dorsal root ganglion neurons, validating Slit2 signaling in primary neurons. Given that CAD cells can be conveniently manipulated using standard molecular biological methods and that the process extension phenotype regulated by Slit2 can be readily traced and quantified, the use of a cell line CAD will facilitate the identification of downstream effectors and elucidation of signaling cascade triggered by Slit. 相似文献