全文获取类型
收费全文 | 57571篇 |
免费 | 4887篇 |
国内免费 | 4913篇 |
出版年
2024年 | 96篇 |
2023年 | 646篇 |
2022年 | 1180篇 |
2021年 | 2877篇 |
2020年 | 1961篇 |
2019年 | 2451篇 |
2018年 | 2507篇 |
2017年 | 1801篇 |
2016年 | 2449篇 |
2015年 | 3585篇 |
2014年 | 4227篇 |
2013年 | 4616篇 |
2012年 | 5412篇 |
2011年 | 4774篇 |
2010年 | 3144篇 |
2009年 | 2497篇 |
2008年 | 3097篇 |
2007年 | 2713篇 |
2006年 | 2435篇 |
2005年 | 2071篇 |
2004年 | 1795篇 |
2003年 | 1635篇 |
2002年 | 1446篇 |
2001年 | 1057篇 |
2000年 | 907篇 |
1999年 | 959篇 |
1998年 | 554篇 |
1997年 | 515篇 |
1996年 | 468篇 |
1995年 | 427篇 |
1994年 | 441篇 |
1993年 | 330篇 |
1992年 | 394篇 |
1991年 | 317篇 |
1990年 | 274篇 |
1989年 | 242篇 |
1988年 | 174篇 |
1987年 | 133篇 |
1986年 | 132篇 |
1985年 | 118篇 |
1984年 | 93篇 |
1983年 | 72篇 |
1982年 | 58篇 |
1981年 | 28篇 |
1980年 | 19篇 |
1979年 | 24篇 |
1976年 | 13篇 |
1975年 | 13篇 |
1973年 | 21篇 |
1958年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 674 毫秒
971.
Tomáš Fiala Jaroslav Holuša Jiří Procházka Lukáš Čížek Marek Dzurenko Jiří Foit Juraj Galko Josef Kašák Jan Kulfan Ferenc Lakatos Oto Nakládal Jiří Schlaghamerský Michal Svatoš Jiří Trombik Petr Zábranský Peter Zach Emanuel Kula 《Journal of Applied Entomology》2020,144(6):423-433
Invasive organisms represent great threats to ecosystems and great challenges to forest management. In Europe, the black timber bark beetle (Xylosandrus germanus) is an invasive secondary pest that mostly attacks the logs of felled trees. We showed the invasion history for Europe and using many local surveys, we summarize the current distribution and other available information on X. germanus in the Czech Republic. We report that this species is distributed from the lowlands to the mountains in the Czech Republic; it is widespread in the eastern half of the country, where it is more abundant in the warmer south and southeast areas than in the cooler areas. Most (78%) of the known localities are at elevation below 400 m a.s.l. Although an ice storm greatly increased X. germanus abundance near the border with Austria, its high abundance did not result in damage to standing trees. Presence of X. germanus in the Czech Republic for over 10 years has not led to heavy tree infestation. 相似文献
972.
Ra Mi Woo Min Gu Park Jae Young Choi Dong Hwan Park Jun Young Kim Minghui Wang Hyun Ji Kim Soo Dong Woo Jae Su Kim Yeon Ho Je 《Journal of Applied Entomology》2020,144(7):655-663
Insect growth regulators (IGRs) are effective alternatives to chemical insecticides because of their specificity and low environmental toxicity. Entomopathogenic fungi are an important natural pathogen of insects and have been developed as biological control agents. They produce a wide range of secondary metabolites such as antibiotics, pesticides, growth-promoting or inhibiting compounds and insect attracting agents. In this study, to explore novel IGR substances from entomopathogenic fungi, culture extracts of 189 entomopathogenic fungi isolated from Korean soil samples were investigated for their juvenile hormone (JH)-based IGR activities. Whereas none of the culture extracts exhibited JH agonist (JHA) activity, 14 extracts showed high levels of JH antagonist (JHAN) activity. Among them, culture extract of JEF-145 strain, which was identified as Lecanicillium attenuatum, showed the highest insecticidal against Aedes albopictus and Plutella xylostella. At liquid culture condition, JHAN activity was observed in culture soup rather than mycelial cake, indicating that substances with JHAN activity are released from the JEF-145 strain during culture. Furthermore, while extract from solid cultured JEF-145 strain showed insecticidal activities against both A. albopictus and P. xylostella, that from liquid cultured fungi showed insecticidal activity only against A. albopictus, indicating that L. attenuatum JEF-145 strain produces different kinds of secondary metabolites with JHAN activity depending on culture conditions. These results suggested that JHAN substances derived from entomopathogenic fungi could be usefully exploited to develop novel eco-friendly IGR insecticides. 相似文献
973.
Amino Acids - Kinase-targeted therapy has been widely used as a lifesaving strategy for cancer patients. However, many patients treated with targeted cancer drugs are clinically observed to rapidly... 相似文献
974.
975.
976.
977.
978.
979.
Hongyi Li Yajun Yin Chongqing Yang Min Chen Fang Wang Chao Ma Hua Li Yiya Kong Fusui Ji Jun Hu 《Cell proliferation》2020,53(2)
Fluid in interstitial spaces accounts for ~20% of an adult body weight and flows diffusively for a short range. Does it circulate around the body like vascular circulations? This bold conjecture has been debated for decades. As a conventional physiological concept, interstitial space is a micron‐sized space between cells and vasculature. Fluid in interstitial spaces is thought to be entrapped within interstitial matrix. However, our serial data have further defined a second space in interstitium that is a nanosized interfacial transport zone on a solid surface. Within this fine space, fluid along a solid fibre can be transported under a driving power and identically, interstitial fluid transport can be visualized by tracking the oriented fibres. Since 2006, our data from volunteers and cadavers have revealed a long‐distance extravascular pathway for interstitial fluid flow, comprising at least four types of anatomic distributions. The framework of each extravascular pathway contains the longitudinally assembled and oriented fibres, working as a fibrorail for fluid flow. Interestingly, our data showed that the movement of fluid in a fibrous pathway is in response to a dynamic driving source and named as dynamotaxis. By analysis of previous studies and our experimental results, a hypothesis of interstitial fluid circulatory system is proposed. 相似文献
980.
Nana Yang Qiao Cao Shuyang Hu Chenchen Xu Ke Fan Feifei Chen Cai-Guang Yang Haihua Liang Min Wu Taeok Bae Lefu Lan 《Molecular microbiology》2020,114(3):423-442
Intracellular protein degradation is essential for the survival of all organisms, but its role in interspecies interaction is unknown. Here, we show that the ClpXP protease of Pseudomonas aeruginosa suppresses its antimicrobial activity against Staphylococcus aureus, a common pathogen co-isolated with P. aeruginosa from polymicrobial human infections. Using proteomic, biochemical, and molecular genetic approaches, we found that this effect is due to the inhibitory effects of ClpXP on the quorum sensing (QS) of P. aeruginosa, mainly by degrading proteins (e.g., PhnA, PhnB, PqsR, and RhlI) which are critical for the production of QS signal molecules PQS and C4-HSL. We provide evidence that co-culturing with S. aureus induces a decrease in the activity of ClpXP in P. aeruginosa, an effect which was also achieved by the treatment of P. aeruginosa with N-acetylglucosamine (GlcNAc), a widespread chemical present on the surface of diverse cell types from bacteria to humans. These findings extend the range of biological events governed by proteolytic machinery to microbial community structure, thus also suggesting that a chemical-induced alteration of protein homeostasis is a mechanism for interspecies interactions. 相似文献