全文获取类型
收费全文 | 6423篇 |
免费 | 747篇 |
国内免费 | 1135篇 |
出版年
2024年 | 30篇 |
2023年 | 120篇 |
2022年 | 282篇 |
2021年 | 405篇 |
2020年 | 314篇 |
2019年 | 384篇 |
2018年 | 359篇 |
2017年 | 286篇 |
2016年 | 314篇 |
2015年 | 540篇 |
2014年 | 584篇 |
2013年 | 617篇 |
2012年 | 746篇 |
2011年 | 637篇 |
2010年 | 415篇 |
2009年 | 329篇 |
2008年 | 368篇 |
2007年 | 278篇 |
2006年 | 245篇 |
2005年 | 205篇 |
2004年 | 178篇 |
2003年 | 133篇 |
2002年 | 121篇 |
2001年 | 71篇 |
2000年 | 66篇 |
1999年 | 59篇 |
1998年 | 37篇 |
1997年 | 28篇 |
1996年 | 13篇 |
1995年 | 16篇 |
1994年 | 27篇 |
1993年 | 20篇 |
1992年 | 18篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1970年 | 1篇 |
1957年 | 1篇 |
1950年 | 1篇 |
排序方式: 共有8305条查询结果,搜索用时 15 毫秒
991.
Pavan Kumar Etzel Garrido Kun Zhao Yi Zheng Saleh Alseekh Erandi Vargas-Ortiz Alisdair R. Fernie Zhangjun Fei Katja Poveda Georg Jander 《植物学报(英文版)》2018,60(11):1083-1096
In response to infestation with larvae of the Guatemalan tuber moth(Tecia solanivora), some Solanum tuberosum(potato) varieties exhibit an overcompensation response, whereby the total dry mass of uninfested tubers is increased. Here, we describe early responses,within the first few days, of T. solanivora feeding, in the Colombian potato variety Pastusa Suprema. Nontargeted metabolite profiling showed significant secondary metabolism changes in T. solanivora-infested tubers,but not in uninfested systemic tubers. In contrast,changes in primary metabolism were greater in uninfested systemic tubers than in the infested tubers, with a notable 80% decline in systemic tuber sucrose levels within 1 d of T. solanivora infestation. This suggested either decreased sucrose transport from the leaves orincreased sink strength, i.e., more rapid sucrose to starch conversion in the tubers. Increased sucrose synthesis was indicated by higher rubisco activase and lower starch synthase gene expression in the leaves of infested plants.Elevated sink strength was demonstrated by 45% more total starch deposition in systemic tubers of T. solanivorainfested plants compared to uninfested control plants.Thus, rather than investing in increased defense of uninfested tubers, Pastusa Suprema promotes deposition of photoassimilates in the form of starch as a response to T. solanivora infestation. 相似文献
992.
993.
Yunyun Wang Wen Gu Yu Shan Fei Liu Xu Xu Yiqin Yang Qiangjian Zhang Yan Zhang Hongbo Kuang Zhonglong Wang Shifa Wang 《Bioorganic & medicinal chemistry letters》2017,27(11):2360-2363
A series of new nopinone-based thiosemicarbazone derivatives were designed and synthesized as potent anticancer agents. All these compounds were identified by 1H NMR, 13C NMR, HR-MS spectra analyses. In the in vitro anticancer activity, most derivatives showed considerable cytotoxic activity against three human cancer cell lines (MDA-MB-231, SMMC-7721 and Hela). Among them, compound 4i exhibited most potent antitumor activity against three cancer cell lines with the IC50 values of 2.79 ± 0.38, 2.64 ± 0.17 and 3.64 ± 0.13 μM, respectively. Furthermore, the cell cycle analysis indicated that compound 4i caused cell cycle arrest of MDA-MB-231 cells at G2/M phase. The Annexin V-FITC/7-AAD dual staining assay also revealed that compound 4i induced the early apoptosis of MDA-MB-231 cells. 相似文献
994.
Alan Xiangdong Wang Jie Chen Qian Zhao Li-Qiang Sun Jacques Friborg Fei Yu Dennis Hernandez Andrew C. Good Herbert E. Klei Ramkumar Rajamani Kathy Mosure Jay O. Knipe Danshi Li Jialong Zhu Paul C. Levesque Fiona McPhee Nicholas A. Meanwell Paul M. Scola 《Bioorganic & medicinal chemistry letters》2017,27(3):590-596
The design and synthesis of a series of tripeptide acylsulfonamides as potent inhibitors of the HCV NS3/4A serine protease is described. These analogues house a C4 aryl, C4 hydroxy-proline at the S2 position of the tripeptide scaffold. Information relating to structure-activity relationships as well as the pharmacokinetic and cardiovascular profiles of these analogues is provided. 相似文献
995.
Yazhou Wang Wei Huang Minhang Xin Pan Chen Li Gui Xinge Zhao Feng Tang Jia Wang Fei Liu 《Bioorganic & medicinal chemistry》2017,25(1):75-83
Janus kinases inhibitor is considered to have therapeutic potential for the treatment of oncology and immune-inflammatory diseases. Two series of 4-(2-benzofuranyl)pyrimidin-2-amine and 4-(4,5,6,7-tetrahydrofuro[3,2-c]pyridin-2-yl)pyrimidin-2-amine derivatives have been designed and synthesized. Primary SAR studies resulted in the discovery of a novel class of 4,5,6,7-tetrahydrofuro[3,2-c]pyridine based JAK2 inhibitors with higher potency (IC50 of 0.7 nM) and selectivity (>30 fold) to JAK3 kinase than tofacitinib. 相似文献
996.
为探究树木径向生长的影响因子,基于对长白山阔叶红松林25 hm2样地中3个常见树种红松、紫椴、蒙古栎连续5年的生长环监测数据,分析各树种的季节生长变化,比较树种间的生长速率差异,并分析初始径级、邻体树木竞争、土壤、地形因素等对不同树种径向生长的作用.结果表明: 3个树种径向生长的季节变化趋势一致,树木于5月末开始生长,7月是生长旺盛期,8月底生长开始减缓,于10月中下旬停止生长.3个树种的径向相对生长率存在显著差异,蒙古栎相对径向生长率显著高于红松和紫椴,该差异在小、中径级个体中表现更为显著.3个树种径向生长的主要影响因子不同,邻体树木的竞争显著抑制了红松和蒙古栎的径向生长,而紫椴的径向生长主要受初始径级、土壤和地形等因子的影响. 相似文献
997.
The WRKY Transcription Factor Family in Model Plants and Crops 总被引:2,自引:0,他引:2
998.
999.
Characterization of candidate odorant‐binding proteins and chemosensory proteins in the tea geometrid Ectropis obliqua Prout (Lepidoptera: Geometridae)
下载免费PDF全文
![点击此处可从《Archives of insect biochemistry and physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
1000.
Ruifen Zhang Dongxiao Su Fangli Hou Lei Liu Fei Huang Lihong Dong 《Bioscience, biotechnology, and biochemistry》2017,81(8):1576-1585
To establish optimal ultra-high-pressure (UHP)-assisted extraction conditions for procyanidins from lychee pericarp, a response surface analysis method with four factors and three levels was adopted. The optimum conditions were as follows: 295 MPa pressure, 13 min pressure holding time, 16.0 mL/g liquid-to-solid ratio, and 70% ethanol concentration. Compared with conventional ethanol extraction and ultrasonic-assisted extraction methods, the yields of the total procyanidins, flavonoids, and phenolics extracted using the UHP process were significantly increased; consequently, the oxygen radical absorbance capacity and cellular antioxidant activity of UHP-assisted lychee pericarp extracts were substantially enhanced. LC-MS/MS and high-performance liquid chromatography quantification results for individual phenolic compounds revealed that the yield of procyanidin compounds, including epicatechin, procyanidin A2, and procyanidin B2, from lychee pericarp could be significantly improved by the UHP-assisted extraction process. This UHP-assisted extraction process is thus a practical method for the extraction of procyanidins from lychee pericarp. 相似文献