全文获取类型
收费全文 | 10650篇 |
免费 | 834篇 |
出版年
2023年 | 97篇 |
2022年 | 138篇 |
2021年 | 312篇 |
2020年 | 191篇 |
2019年 | 240篇 |
2018年 | 281篇 |
2017年 | 267篇 |
2016年 | 393篇 |
2015年 | 580篇 |
2014年 | 642篇 |
2013年 | 820篇 |
2012年 | 901篇 |
2011年 | 822篇 |
2010年 | 485篇 |
2009年 | 512篇 |
2008年 | 617篇 |
2007年 | 531篇 |
2006年 | 507篇 |
2005年 | 469篇 |
2004年 | 445篇 |
2003年 | 385篇 |
2002年 | 367篇 |
2001年 | 146篇 |
2000年 | 97篇 |
1999年 | 115篇 |
1998年 | 104篇 |
1997年 | 93篇 |
1996年 | 75篇 |
1995年 | 59篇 |
1994年 | 59篇 |
1993年 | 56篇 |
1992年 | 59篇 |
1991年 | 43篇 |
1990年 | 43篇 |
1989年 | 41篇 |
1988年 | 32篇 |
1987年 | 46篇 |
1986年 | 23篇 |
1985年 | 37篇 |
1984年 | 42篇 |
1983年 | 31篇 |
1982年 | 31篇 |
1981年 | 32篇 |
1980年 | 19篇 |
1978年 | 19篇 |
1977年 | 27篇 |
1975年 | 14篇 |
1974年 | 21篇 |
1973年 | 18篇 |
1972年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 321 毫秒
981.
982.
Diana?Negr?o?Cavalcanti Meire-Anne?Rezende?de?Oliveira Joel?Campos?De-Paula Leandro?Silva?Barbosa Tamara?Fogel Marcelo?Alves?Pinto Izabel?Christina?Nunes?de?Palmer Paix?o Valéria?Laneuville?TeixeiraEmail author 《Journal of applied phycology》2011,23(5):873-876
This study evaluated the variability in the production of an HIV-1 antiviral diterpene in individuals of Dictyota menstrualis throughout reproductive stages. The brown alga Dictyota has an isomorphic biphasic life cycle. The quantification of the active principle by GC–FID indicated a greater production
of the diterpene in the female gametophytic phase (42.11 ppm). However, these individuals had the highest variation between
individuals (standard deviation of 68.20 ppm in the range from 0.39 to 227 ppm). Sporophytic individuals showed less variability.
This variability in the production of the antiviral diterpene is important to the development of future antiviral drugs. 相似文献
983.
Sielaff F Than ME Bevec D Lindberg I Steinmetzer T 《Bioorganic & medicinal chemistry letters》2011,21(2):836-840
A novel series of amidinohydrazone-derived furin inhibitors was prepared; the most potent compounds 17 and 21 inhibit furin with Ki values of 0.46 and 0.59 μM, respectively. In contrast to inhibitor 17, which still contains a guanidino residue, compound 21 possesses only weakly basic amidinohydrazone groups. 相似文献
984.
Navarrete-Vazquez G Chávez-Silva F Argotte-Ramos R Rodríguez-Gutiérrez Mdel C Chan-Bacab MJ Cedillo-Rivera R Moo-Puc R Hernández-Nuñez E 《Bioorganic & medicinal chemistry letters》2011,21(10):3168-3171
We have synthesized two new benzologues of Nitazoxanide (NIT) and Tizoxanide (TIZ), using a short synthetic route. Both compounds were tested in vitro against six protozoa (Giardia intestinalis, Trichomonas vaginalis, Entamoeba histolytica, Plasmodium berghei, Leishmania mexicana and Trypanosoma cruzi). Compound 1 (benzologue of NIT) showed broad antiprotozoal effect against all parasites tested, showing IC50’s <5μM. This compound was five-times more active than NIT, and 18-times more potent than metronidazole against G. intestinalis. It was 10-times more active than pentamidine against L. mexicana, and it was sevenfold more potent than benznidazole versus T. cruzi. This compound could be considered as a new broad spectrum antiprotozoal agent. 相似文献
985.
986.
Biofiltration of reduced sulphur compounds and community analysis of sulphur-oxidizing bacteria 总被引:2,自引:0,他引:2
Ramírez M Fernández M Granada C Le Borgne S Gómez JM Cantero D 《Bioresource technology》2011,102(5):4047-4053
The present work aims to use a two-stage biotrickling filters for simultaneous treatment of hydrogen sulphide (H2S), methyl mercaptan (MM), dimethyl sulphide (DMS) and dimethyl disulphide (DMDS). The first biofilter was inoculated with Acidithiobacillus thiooxidans (BAT) and the second one with Thiobacillus thioparus (BTT). For separate feeds of reduced sulphur compounds (RSC), the elimination capacity (EC) order was DMDS > DMS > MM. The EC values were 9.8 gMM-S/m3/h (BTT; 78% removal efficiency (RE); empty bed residence time (EBRT) 58 s), 36 gDMDS-S/m3/h (BTT; 94.4% RE; EBRT 76 s) and 57.5 gH2S-S/m3/h (BAT; 92% RE; EBRT 59 s). For the simultaneous removal of RSC in BTT, an increase in the H2S concentration from 23 to 293 ppmv (EBRT of 59 s) inhibited the RE of DMS (97-84% RE), DMDS (86-76% RE) and MM (83-67% RE). In the two-stage biofiltration, the RE did not decrease on increasing the H2S concentration from 75 to 432 ppmv. 相似文献
987.
988.
989.