全文获取类型
收费全文 | 4370篇 |
免费 | 398篇 |
国内免费 | 84篇 |
出版年
2023年 | 24篇 |
2022年 | 78篇 |
2021年 | 127篇 |
2020年 | 68篇 |
2019年 | 112篇 |
2018年 | 133篇 |
2017年 | 110篇 |
2016年 | 127篇 |
2015年 | 218篇 |
2014年 | 271篇 |
2013年 | 289篇 |
2012年 | 384篇 |
2011年 | 346篇 |
2010年 | 237篇 |
2009年 | 180篇 |
2008年 | 257篇 |
2007年 | 218篇 |
2006年 | 202篇 |
2005年 | 191篇 |
2004年 | 174篇 |
2003年 | 145篇 |
2002年 | 139篇 |
2001年 | 71篇 |
2000年 | 85篇 |
1999年 | 65篇 |
1998年 | 40篇 |
1997年 | 39篇 |
1996年 | 31篇 |
1995年 | 31篇 |
1994年 | 26篇 |
1993年 | 28篇 |
1992年 | 38篇 |
1991年 | 52篇 |
1990年 | 22篇 |
1989年 | 37篇 |
1988年 | 24篇 |
1987年 | 29篇 |
1986年 | 16篇 |
1985年 | 23篇 |
1984年 | 11篇 |
1983年 | 16篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 13篇 |
1978年 | 15篇 |
1975年 | 7篇 |
1974年 | 9篇 |
1973年 | 11篇 |
1971年 | 8篇 |
排序方式: 共有4852条查询结果,搜索用时 31 毫秒
1.
2.
Plant and Soil - Agricultural practices often have persistent effects on soil physicochemical properties and soil biota, which can feedback to influence plant performance. We investigated... 相似文献
3.
Wei Liu Yaoting Sun Weigang Ge Fangfei Zhang Lin Gan Yi Zhu Tiannan Guo Kexin Liu 《Molecular & cellular proteomics : MCP》2022,21(2):100187
Drug resistance is a critical obstacle to effective treatment in patients with chronic myeloid leukemia. To understand the underlying resistance mechanisms in response to imatinib mesylate (IMA) and adriamycin (ADR), the parental K562 cells were treated with low doses of IMA or ADR for 2 months to generate derivative cells with mild, intermediate, and severe resistance to the drugs as defined by their increasing resistance index. PulseDIA-based (DIA [data-independent acquisition]) quantitative proteomics was then employed to reveal the proteome changes in these resistant cells. In total, 7082 proteins from 98,232 peptides were identified and quantified from the dataset using four DIA software tools including OpenSWATH, Spectronaut, DIA-NN, and EncyclopeDIA. Sirtuin signaling pathway was found to be significantly enriched in both ADR-resistant and IMA-resistant K562 cells. In particular, isocitrate dehydrogenase (NADP(+)) 2 was identified as a potential drug target correlated with the drug resistance phenotype, and its inhibition by the antagonist AGI-6780 reversed the acquired resistance in K562 cells to either ADR or IMA. Together, our study has implicated isocitrate dehydrogenase (NADP(+)) 2 as a potential target that can be therapeutically leveraged to alleviate the drug resistance in K562 cells when treated with IMA and ADR. 相似文献
4.
Sung Ho Son Sung Mee Choi Kum Boo Choi Yun Hee Lee Dea Sook Lee Myung Suk Choi Young Goo Park 《Biotechnology and Bioprocess Engineering》1999,4(2):112-118
Calli were induced from 300,000 embryos isolated from immature to mature stage of seeds collected on late September from 14
elite trees. When the embryos were cultured onto plastic Petri-dish containing 20 mL of modified B5 basal medium supplemented
with 3% (w/v) sucrose, 500 mg/L casein hydrolysate, 250 mg/L myo-inositol, 0.5% (w/v) polyvinyl polypyrrolidon (PVPP), 2×MS
vitamins, 0.5 mg/L gibberellic acid, and 10 mg/L 2,4-D after 2 weeks of culture, yellowish-white calli were immediately formed
on the surfaces of embryos, and subcultured for 4 weeks in same culture medium. Because most of calli maintained for more
than 3 months were revealed differences in their colors, surface texture, and growth rate, visual selection was made for first
round screening. When the size of visually selected calli larger than 19 mm in their diameter were inoculated, persistent
proliferation was observed. Among the plating methods tested for the selection of rapid growing cell lines at single cell
and/or small cell aggregate level, 2-layer spread plating revealed as the best for single cell cloning. To enhance cell growth
and maintain high rate of viability for long-term culture of yew cells in bioreactor, final cell volume less than 50% in SCV
seemed to be the best. Time course study revealed that 30% of inoculum density was suitable for fed batch culture. Among the
tested conditional media, the rate of 1∶2 (old medium: fresh medium) was recorded at the best for cell growth. 相似文献
5.
Aurin tricarboxylic acid, the anti-AIDS compound, prevents the binding of interferon-alpha to its receptor 总被引:2,自引:0,他引:2
Y X Gan J L Weaver P S Pine K C Zoon A Aszalos 《Biochemical and biophysical research communications》1990,172(3):1298-1303
Binding of HIV to its receptor, the CD4 molecule of lymphocytes, can be prevented by chemical agents. These agents could be considered as potential anti-AIDS drugs. We have shown that aurin tricarboxylic acid (ATA, 3 microM) specifically blocks the binding of gp120, the HIV coat protein, to the CD4 molecule. We have also found that ATA prevents the binding of interferon-alpha to its receptor in a dose-dependent manner (12-50 microM range). Membrane potential shift, associated with binding of interferon-alpha to its receptor, was also blocked by ATA in a dose-dependent fashion. Our results indicate that potential anti-AIDS drugs should be screened for such undesired side effects. 相似文献
6.
Abdulrazak Osama Han Ming Gan Cindy Shuan Ju Teh Kien-Pong Yap Kwai-Lin Thong 《Journal of bacteriology》2012,194(24):6933
The genome sequence analysis of a clinical Vibrio cholerae VC35 strain from an outbreak case in Malaysia indicates multiple genes involved in host adaptation and a novel Na+-driven multidrug efflux pump-coding gene in the genome of Vibrio cholerae with the highest similarity to VMA_001754 of Vibrio mimicus VMA223. 相似文献
7.
Experiments have shown that the block of proventriculus develops in 1.1 to 1.5% of individuals of the flea Neopsylla abagaitui infected with plague microbe. These insects transmit the agent during bloodsucking to different plague carriers (Citellus dauricus, C. undulatus, Meriones unguiculatus, Microtus gregalis). The plague microbe is preserved in fleas for 65 days (the observation period). 相似文献
8.
Effects of tissue position (viz. outer vs inner mesocarp) and heat treatment (48°C, 20 min) on variations in polygalacturonase (EC 3.2.1.15 and EC 3.2.1.67) activity and ripening of fruits of Carica papaya L. cv. Backcross Solo were investigated. Polygalacturonase activity increased during ripening concomitantly with an increase in tissue softness and soluble polyuronide level. Throughout ripening, inner mesocarp tissue was softer and contained higher polygalacturonase activity than outer mesocarp tissue. Titratable acidity as well as ß-galactosidase (EC 3.2.1.23) activity also increased during ripening; however, unlike polygalacturonase, their level or activity was lower in inner than in outer mesocarp. Ascorbic acid could partially account for the increase in titratable acidity during ripening but contributed very little to the differences in titratable acid levels between outer and inner mesocarp. Heat treatment had no effect on either fruit softness or titratable acidity, but it markedly reduced the increase in ascorbic acid and polygalacturonase activity during ripening. Ripening, as reflected by changes in tissue softness and polygalacturonase activity, progressed outwardly from the interior towards the exterior of the fruit. The effect of heat treatment in suppressing polygalacturonase activity was relatively greater in inner than in outer mesocarp, suggesting that sensitivity of the enzyme to heat treatment may vary with stage of ripeness of the tissue. 相似文献
9.
The cell cycle of the photosynthetic unicellular alga Euglena gracilis growing in phototrophic medium is regulated by light. To investigate the relationship of this cell cycle response to light stimulated photosynthesis, we have tested the effect of the photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) on Euglena cell cycle transit. While DCMU does not block light stimulated cells from entering the S phase of the cell cycle, it does inhibit the transit through G2/M. The specificity of this response and its relationship to photosynthesis was studied by looking at the effect of DCMU on dark grown wild-type cells, and on two bleached variants of Euglena (W3BUL and W10BSmL) that lack chloroplasts. The drug does block G2/M in these cells, but not entrance into the cell cycle. Our studies show that entrance of cells into the cell cycle from a quiescent state does not require active photosynthesis, and that DCMU has effects on G2/M transit that are independent of the photosynthetic capacity of the cells. 相似文献
10.
Use of a glucocorticoid-inducible promoter for expression of herpes simplex virus type 1 glycoprotein gC1, a cytotoxic protein in mammalian cells. 总被引:3,自引:0,他引:3 下载免费PDF全文