全文获取类型
收费全文 | 9418篇 |
免费 | 529篇 |
国内免费 | 911篇 |
专业分类
林业 | 1020篇 |
农学 | 1118篇 |
基础科学 | 498篇 |
1143篇 | |
综合类 | 3639篇 |
农作物 | 579篇 |
水产渔业 | 460篇 |
畜牧兽医 | 1301篇 |
园艺 | 522篇 |
植物保护 | 578篇 |
出版年
2024年 | 51篇 |
2023年 | 140篇 |
2022年 | 382篇 |
2021年 | 402篇 |
2020年 | 413篇 |
2019年 | 375篇 |
2018年 | 243篇 |
2017年 | 368篇 |
2016年 | 286篇 |
2015年 | 454篇 |
2014年 | 443篇 |
2013年 | 559篇 |
2012年 | 681篇 |
2011年 | 732篇 |
2010年 | 657篇 |
2009年 | 574篇 |
2008年 | 578篇 |
2007年 | 558篇 |
2006年 | 545篇 |
2005年 | 472篇 |
2004年 | 240篇 |
2003年 | 154篇 |
2002年 | 181篇 |
2001年 | 223篇 |
2000年 | 184篇 |
1999年 | 161篇 |
1998年 | 127篇 |
1997年 | 105篇 |
1996年 | 84篇 |
1995年 | 97篇 |
1994年 | 73篇 |
1993年 | 64篇 |
1992年 | 48篇 |
1991年 | 47篇 |
1990年 | 44篇 |
1989年 | 37篇 |
1988年 | 29篇 |
1987年 | 17篇 |
1986年 | 9篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1956年 | 3篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
3.
Zong-Qing Huo Feng Zhu Xing-Wang Zhang Xiao Zhang Hong-Bao Liang Jing-Chun Yao Zhong Liu Gui-Min Zhang Qing-Qiang Yao Guo-Fei Qin 《Marine drugs》2022,20(5)
Flexible marine natural products (MNPs), such as eribulin and bryostatin, play an important role in the development of modern marine drugs. However, due to the multiple chiral centers and geometrical uncertainty of flexible systems, configuration determinations of flexible MNPs face great challenges, which, in turn, have led to obstacles in druggability research. To resolve this issue, the comprehensive use of multiple methods is necessary. Additionally, configuration assignment methods, such as X-ray single-crystal diffraction (crystalline derivatives, crystallization chaperones, and crystalline sponges), NMR-based methods (JBCA and Mosher’s method), circular dichroism-based methods (ECCD and ICD), quantum computational chemistry-based methods (NMR calculations, ECD calculations, and VCD calculations), and chemical transformation-based methods should be summarized. This paper reviews the basic principles, characteristics, and applicability of the methods mentioned above as well as application examples to broaden the research and applications of these methods and to provide a reference for the configuration determinations of flexible MNPs. 相似文献
4.
5.
6.
7.
Ting Zhang Faming Yang Xiaoming Qin Xianmei Yang Chaohua Zhang Zhaoyi Wan Haisheng Lin 《Marine drugs》2022,20(7)
Previous studies found that both oral and topical administration of enzymatic digestion products < 3 K Da ultrafiltration fractions of Pinctada martensii mantle (PMPs) had pro-healing effects. Thus, we further purified them by Sephadex-G25 and screened them by cellular assays to obtain Pinctada martensii purified peptides (PMPPs). In this study, we explored the mechanism of PMPPs on wound healing by in vivo, in vitro, and in silico experiments. LC-MS/MS results showed that PMPPs consisted of 33 peptides with molecular weights ranging from 758.43 to 2014.04 Da, and the characteristic peptide was Leu-Asp. The results of cellular assays showed that PMPPs promoted the proliferation of human skin fibroblasts (HSF) (135%) and human immortalized keratinocyte (HaCaT) cells (125%) very significantly at 12.5 μg/mL. The in vivo results showed that PMPPs could achieve scarless healing by inhibiting the inflammatory response, accelerating the epithelialization process, and regulating collagen I/III ratio. The optimal peptide sequence FAFQAEIAQLMS of PMPPs was screened for key protein receptors in wound healing (EGFR1, FGFR1, and MMP-1) with the help of molecular docking technique, which also showed to be the key pro-healing active peptide sequence. Therefore, it may provide a therapeutic strategy with great potential for wound healing. 相似文献
8.
9.
马铃薯Y病毒云南昭通烟草分离物的检测及年度间差异比较 总被引:1,自引:0,他引:1
利用DAS-ELISA检测试剂盒检测昭通烟草脉斑病样品,结果表明存在马铃薯Y病毒O株系和马铃薯Y病毒N株系两个不同株系病毒。利用Sprimer和M4引物扩增、克隆、测序,得到长度为1 771 bp目的片段,该片段包含病毒的外壳蛋白基因序列、3′ UTR序列以及部分Nib基因序列;序列分析表明与湖南HN 2分离物(GenBank No. GQ200836)和美国NE 11分离物(GenBank No. DQ157180)核苷酸序列相似性均为98%,系统进化分析表明其具有较近的亲缘关系。 相似文献
10.