全文获取类型
收费全文 | 7007篇 |
免费 | 321篇 |
国内免费 | 1篇 |
出版年
2023年 | 35篇 |
2022年 | 26篇 |
2021年 | 76篇 |
2020年 | 89篇 |
2019年 | 118篇 |
2018年 | 270篇 |
2017年 | 241篇 |
2016年 | 314篇 |
2015年 | 222篇 |
2014年 | 331篇 |
2013年 | 502篇 |
2012年 | 383篇 |
2011年 | 535篇 |
2010年 | 306篇 |
2009年 | 206篇 |
2008年 | 374篇 |
2007年 | 425篇 |
2006年 | 461篇 |
2005年 | 390篇 |
2004年 | 326篇 |
2003年 | 368篇 |
2002年 | 286篇 |
2001年 | 186篇 |
2000年 | 158篇 |
1999年 | 107篇 |
1998年 | 63篇 |
1997年 | 22篇 |
1996年 | 15篇 |
1995年 | 19篇 |
1994年 | 15篇 |
1993年 | 14篇 |
1991年 | 19篇 |
1990年 | 12篇 |
1989年 | 11篇 |
1988年 | 10篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 25篇 |
1984年 | 23篇 |
1983年 | 15篇 |
1982年 | 16篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1979年 | 19篇 |
1978年 | 18篇 |
1977年 | 15篇 |
1953年 | 18篇 |
1952年 | 40篇 |
1888年 | 14篇 |
1887年 | 14篇 |
排序方式: 共有7329条查询结果,搜索用时 15 毫秒
991.
992.
993.
Effect of Asahi SL on China aster ‘Aleksandra’ seed yield, germination and some metabolic events 总被引:2,自引:0,他引:2
The effects of Asahi SL (sodium ortho and para-nitro phenolate, sodium 5 nitro guaiacolate) sprays on China aster plant height,
seed yield and some metabolic events were investigated. The plants were sprayed with Asahi SL, in concentration of 0, 0.1,
0.2 or 0.4 %, three times before or during flowering, and six times before and during this stage. It was found that Asahi
SL applied three times during flowering brought about an increase in the seed yield, germination and metabolic activity and
did not modify vegetative growth of plants. The chemical used earlier, before flowering, had detrimental effect on seed yield
and quality, although it stimulated vegetative growth. The positive effect of Asahi SL was more prominent in weather conditions
unfavourable for seed production. 相似文献
994.
995.
Br. Błocki 《Plant Systematics and Evolution》1884,34(7):249-251
Ohne Zusammenfassung 相似文献
996.
Mikołaj Świerczyński Agata Szymaszkiewicz Jakub Fichna Marta Zielińska 《生物化学与生物物理学报:癌评论》2021,1875(1):188460
Colorectal cancer (CRC) is one of the most common cause of death among neoplasms around the world. The environmental factors, like diet and obesity, are crucial in CRC pathogenesis by creating cancer-favorable microenvironment and hormonal changes. Adiponectin, the adipose tissue-specific hormone, is generally considered to negatively correlate with CRC development. The interleukin 6 (IL-6) is one of the most important pro-inflammatory cytokine connected with CRC, which is strongly inflammation-associated. The opioids are variable group substantially correlated with cancers - the endogenous opioids affect immune system and cell cycle including proliferation and cell death whereas exogenous opioids are leading clinically used analgesics in terminal cancer patients. In this review we discuss the involvement of adiponectin, IL-6 and opioids in CRC pathogenesis, their link with obesity, possible cross-talk and potential novel therapeutic approach in CRC treatment. 相似文献
997.
998.
Joanna Papierska Bartłomiej S. Witkowski Anastasiya Derkachova Krzysztof P. Korona Johannes Binder Krzysztof Gałkowski Łukasz Wachnicki Marek Godlewski Tomasz Dietl Jan Suffczyński 《Plasmonics (Norwell, Mass.)》2013,8(2):913-919
A simple fabrication method of silver (Ag) nanoislands on ZnO films is presented. Continuous wave and time-resolved photoluminescence and transmission are employed to investigate modifications of visible and UV emissions of ZnO brought about by coupling to localized surface plasmons residing on Ag nanoislands. The size of the nanoislands, determining their absorption and scattering efficiencies, is found to be an important factor governing plasmonic modification of optical response of ZnO films. The presence of the Ag nanoislands of appropriate dimensions causes a strong (threefold) increase in emission intensity and up to 1.5 times faster recombination. The experimental results are successfully described by model calculations within the Mie theory. 相似文献
999.
Katarzyna Szczepańska Tadeusz Karcz Magdalena Kotańska Agata Siwek Kamil J. Kuder Gniewomir Latacz Szczepan Mogilski Stefanie Hagenow Annamaria Lubelska Michał Sobolewski Holger Stark Katarzyna Kieć-Kononowicz 《Bioorganic & medicinal chemistry》2018,26(23-24):6056-6066
As a continuation of our search for novel histamine H3 receptor ligands, a series of new acetyl and propionyl phenoxyalkylamine derivatives (2–25) was synthesized. Compounds with three to four carbon atoms alkyl chain spacer, composed of six various 4N-substituted piperazine moieties were evaluated for their binding properties at human histamine H3 receptors (hH3R). In vitro test results proved the 4-pyridylpiperazine moiety as crucial element for high hH3R affinity (hH3R Ki?=?5.2–115?nM). Moreover introduction of carbonyl group containing residues in the lipophilic part of molecules instead of branched alkyl substituents resulted in increased affinity in correlation to previously described series, whereas propionyl derivatives showed slightly higher affinities than those of acetyl (16 and 22vs.4 and 10; hH3R Ki?=?5.2 and 15.4?nM vs. 10.2 and 115?nM, respectively). These findings were confirmed by molecular modelling studies, demonstrating multiple ligand-receptor interactions. Furthermore, pharmacological in vivo test results of compound 4 clearly indicate that it may affect the amount of calories consumed, thus act as an anorectic compound. Likewise, its protective action against hyperglycemia and the development of overweight has been shown. In order to estimate drug-likeness of compound 4, in silico and experimental evaluation of metabolic stability in human liver microsomes was performed. 相似文献
1000.
TMEFF2 shedding is regulated by oxidative stress and mediated by ADAMs and transmembrane serine proteases implicated in prostate cancer 下载免费PDF全文
Katarzyna Gaweł‐Bęben Nazim Ali Vincent Ellis Gloria Velasco Zaruhi Poghosyan Ann Ager Vera Knäuper 《Cell biology international》2018,42(3):273-280
TMEFF2 is a type I transmembrane protein with two follistatin (FS) and one EGF‐like domain over‐expressed in prostate cancer; however its biological role in prostate cancer development and progression remains unclear, which may, at least in part, be explained by its proteolytic processing. The extracellular part of TMEFF2 (TMEFF2‐ECD) is cleaved by ADAM17 and the membrane‐retained fragment is further processed by the gamma‐secretase complex. TMEFF2 shedding is increased with cell crowding, a condition associated with the tumour microenvironment, which was mediated by oxidative stress signalling, requiring jun‐kinase (JNK) activation. Moreover, we have identified that TMEFF2 is also a novel substrate for other proteases implicated in prostate cancer, including two ADAMs (ADAM9 and ADAM12) and the type II transmembrane serine proteinases (TTSPs) matriptase‐1 and hepsin. Whereas cleavage by ADAM9 and ADAM12 generates previously identified TMEFF2‐ECD, proteolytic processing by matriptase‐1 and hepsin produced TMEFF2 fragments, composed of TMEFF2‐ECD or FS and/or EGF‐like domains as well as novel membrane retained fragments. Differential TMEFF2 processing from a single transmembrane protein may be a general mechanism to modulate transmembrane protein levels and domains, dependent on the repertoire of ADAMs or TTSPs expressed by the target cell. 相似文献