全文获取类型
收费全文 | 3028篇 |
免费 | 305篇 |
国内免费 | 462篇 |
专业分类
3795篇 |
出版年
2024年 | 10篇 |
2023年 | 50篇 |
2022年 | 122篇 |
2021年 | 171篇 |
2020年 | 134篇 |
2019年 | 168篇 |
2018年 | 142篇 |
2017年 | 130篇 |
2016年 | 163篇 |
2015年 | 229篇 |
2014年 | 259篇 |
2013年 | 270篇 |
2012年 | 289篇 |
2011年 | 271篇 |
2010年 | 188篇 |
2009年 | 153篇 |
2008年 | 172篇 |
2007年 | 141篇 |
2006年 | 141篇 |
2005年 | 98篇 |
2004年 | 89篇 |
2003年 | 84篇 |
2002年 | 66篇 |
2001年 | 38篇 |
2000年 | 27篇 |
1999年 | 40篇 |
1998年 | 18篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1981年 | 3篇 |
1978年 | 1篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1950年 | 1篇 |
排序方式: 共有3795条查询结果,搜索用时 0 毫秒
1.
A G Chuchalin V A Babushkina V Ia Arion R D Aspetov T B Sha?khinova 《Biulleten' eksperimental'no? biologii i meditsiny》1984,98(7):76-78
A study was made of the effect of T-activin on the biosynthesis of immune gamma-interferon. It was shown that in 27% of patients with chronic nonspecific pulmonary diseases, production of gamma-interferon by lymphocytes was substantially reduced during exacerbation of inflammatory process in the lungs. It was discovered that T-activin was not an interferon inductor but enhanced its synthesis in patients with a low capacity of producing immune interferon even at small doses of interferon inductor. The preparation does not produce any effect on this process in normal subjects and in patients showing the normal level of gamma-interferon. Thus T-activin can be used for stimulation of interferonogenesis. 相似文献
2.
利用甲基磺酸乙酯(EMS,ethyl methyl sulfonate)诱变剂处理野生型Yugu1(豫谷1号),在后代中发现了一个可以稳定遗传的颖花明显变窄的突变体,将其命名为sins1。与Yugu1相比,突变体sins1的株高显著降低了3.89%,穗长和穗粗分别显著降低了17.42%和21.62%,旗叶叶长和叶宽分别显著降低了15.09%和25.78%,千粒重显著降低了40.96%,谷码数显著降低了25%,均达到显著水平(P0.05)。利用突变体sins1为母本、SSR41为父本构建F_2定位群体,F_2正常颖花与窄颖花植株数目的分离比例为3∶1,表明该突变性状由隐性单基因控制。利用F_2群体隐性单株,最终将突变基因定位在3号染色体上SSR标记3-2658与CAAS3031间约7.709 Mb的距离内,为下一步精细定位提供了基础,同时也为促进禾本科作物颖花的研究提供了方向。 相似文献
3.
4.
5.
Sunitinib, a small-molecule multi-targeted tyrosine kinase inhibitor, has been applied in phase II clinical trial as second-line treatment for advanced gastric cancer. In this study, we determined the effect of Sunitinib on the multidrug resistance in gastric cancer cells selected by vincristine. Our results showed that Sunitinib significantly enhanced the cytotoxicity of adriamycin, vincristine, etoposide, 5-Fluorouracil, and cisplatin in multidrug-resistant gastric cancer cells (SGC7901/VCR). Sunitinib significantly increased the intracellular accumulation and retention of rhodamine 123 in the SGC7901/VCR cells. However, Sunitinib, at a concentration that reverses MDR, had no significant effect on P-gp protein or mRNA expression levels. In addition, the present study revealed that Sunitinib inhibited Stat3 and down-regulated Bcl-2 in SGC7901/VCR cells, which might also contribute to the reversal of MDR. In conclusion, Sunitinib reverses multidrug resistance in gastric cancer cells by inhibiting P-gp transporter function and modulating Stat3 and Bcl-2. Further study with Sunitinib may be helpful for developing combination therapeutic strategy or circumventing gastric cancer MDR to other conventional anti-cancer drugs. 相似文献
6.
7.
8.
盐胁迫下大豆根组织定量PCR分析中内参基因的选择 总被引:1,自引:0,他引:1
实时荧光定量PCR已广泛用于基因表达的分析, 适当的内参基因选择是获得准确分析结果的关键。在大豆(Glycine max)分子生物学研究中, 逆境响应基因和microRNA (miRNA)表达的内参辅助检测基因均有哪些目前尚不清楚。该研究选用不同盐梯度和时间点组合处理的大豆根组织为材料, 对已报道的其它条件下表达相对稳定的内参基因(ACT、ACT2/7、CYP2、ELF1A、ELF1B、F-Box、TUA和UBC2)以及miRNA内参基因(U6、miR1515a、miR1520c、miR1520d、miR171a和miR171b)的表达情况进行了全面检测; 并采用Δ-Ct、Bestkeeper、NormFinder和Genorm四种方法对检测结果进行了综合分析, 发现ELF1B和CYP2适合作为大豆根系盐胁迫响应基因研究的内参基因, miR1515a和U6适合作为盐胁迫下大豆根组织miRNA研究的内参。上述研究结果为大豆盐胁迫响应基因和miRNA表达及其进一步的功能研究奠定了基础。 相似文献
9.
YiFan Liu Chao Luan Xi Xia Sha An YiZhen Wang 《International journal of peptide research and therapeutics》2011,17(3):175-184
In the last few decades, long-term and high-dose usage of antibiotics in livestock diets has led to the emergence of antibiotic resistant bacteria, antibiotic residues in animal products and environmental pollution, adversely affecting animal health. Because of these concerns, a study screening cathelicidin peptides from different animal origins (i.e. protegrin-1 [PG-1], PMAP-23, LL-37, indolicidin and cathelicidin-BF [C-BF]) as antibiotic replacements with higher antimicrobial activity and lower cytotoxicity was designed to study their mechanisms towards enteric pathogens in weaning piglets. PG-1 and C-BF proved to be the most effective bacteriocids with the widest spectra of activity, with the MIC values equal to or lower than commonly used antibiotics towards several Escherichia and Salmonella strains, and showed a synergistic effect with aureomycin. Mechanism studies suggested the C-BF killing mechanism is based on membrane permeability, while multiple targets maybe exist for PG-1, including membrane and intracellular biomacromolecules. Cytotoxicity tests showed PMAP-23 and C-BF exhibited the lowest cytotoxic effects, while PG-1, LL-37 and indolicidin displayed cytotoxicity by dose. This study demonstrated that among the peptides tested, C-BF has the capacity to inactivate enteric pathogens with lower cytotoxicity and is potentially a novel anti-bacterial agent. The activity of PG-1 is highly efficient, with the potential to reduce cytotoxicity using molecular design. 相似文献
10.
竹叶柴胡地上部分的化学成分 总被引:2,自引:0,他引:2
竹叶柴胡(Bupleurum marginatumWall.ex DC.)为伞形科(Apiaceae)柴胡属(BupleurumL.)植物,主要分布于四川北部、陕西南部、湖北西部及云南、贵州等省区,全株均可入药,为目前市场上药材柴胡的三大主要来源之一。柴胡具解表和里、疏肝解郁、提升中气之功效,在中药学中具有重要地位,在中国也已有2000多年的应用历史。目前,有关北柴胡(B.chinenseDC.)及南柴胡(B.scorzonerifoliumWilld.)的相关研究较多,而对在西南地区广泛使用的竹叶柴胡的研究却甚少。另外,对柴胡的相关研究多集中于根及根茎,有关柴胡茎叶化学成分和药理作用的研究较少。… 相似文献