全文获取类型
收费全文 | 1853篇 |
免费 | 191篇 |
出版年
2022年 | 21篇 |
2021年 | 36篇 |
2020年 | 22篇 |
2019年 | 28篇 |
2018年 | 42篇 |
2017年 | 34篇 |
2016年 | 52篇 |
2015年 | 75篇 |
2014年 | 92篇 |
2013年 | 98篇 |
2012年 | 118篇 |
2011年 | 137篇 |
2010年 | 81篇 |
2009年 | 63篇 |
2008年 | 72篇 |
2007年 | 92篇 |
2006年 | 95篇 |
2005年 | 72篇 |
2004年 | 76篇 |
2003年 | 67篇 |
2002年 | 69篇 |
2001年 | 41篇 |
2000年 | 29篇 |
1999年 | 28篇 |
1998年 | 16篇 |
1997年 | 23篇 |
1996年 | 23篇 |
1995年 | 19篇 |
1994年 | 14篇 |
1993年 | 20篇 |
1992年 | 19篇 |
1991年 | 20篇 |
1990年 | 26篇 |
1989年 | 27篇 |
1988年 | 12篇 |
1987年 | 17篇 |
1985年 | 23篇 |
1984年 | 13篇 |
1983年 | 18篇 |
1981年 | 10篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1977年 | 11篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1974年 | 10篇 |
1970年 | 9篇 |
1969年 | 10篇 |
1968年 | 10篇 |
1961年 | 8篇 |
排序方式: 共有2044条查询结果,搜索用时 15 毫秒
51.
52.
Candida lipolytica was grown continuously on n-hexadecane as the main source of carbon. A transient continuous-culture experiment was also conducted to investigate hydrocarbon-limited growth; the hydrocarbon feed flow rate was stopped for several hours and then resumed at a reduced steady-state flow rate. Interfacial tension, Sauter mean diameter, pseudosolubility, fraction of cells in the aqueous phase, oil-phase volume fraction, and cell concentration were measured to characterize the system. The microorganisms appear to utilize both the submicron drops and the microscopic drops. The effects of interfacial tension, pseudosolubility, and unoccupied interfacial area on the kinetics of hydrocarbon fermentation are discussed here. A conceptual model for hydrocarbon uptake is presented and discussed. 相似文献
53.
54.
55.
Uli Ohmayer Michael Gamalinda Martina Sauert Julius Ossowski Gisela P?ll Jan Linnemann Thomas Hierlmeier Jorge Perez-Fernandez Beril Kumcuoglu Isabelle Leger-Silvestre Marlène Faubladier Joachim Griesenbeck John Woolford Herbert Tschochner Philipp Milkereit 《PloS one》2013,8(7)
During the assembly process of ribosomal subunits, their structural components, the ribosomal RNAs (rRNAs) and the ribosomal proteins (r-proteins) have to join together in a highly dynamic and defined manner to enable the efficient formation of functional ribosomes. In this work, the assembly of large ribosomal subunit (LSU) r-proteins from the eukaryote S. cerevisiae was systematically investigated. Groups of LSU r-proteins with specific assembly characteristics were detected by comparing the protein composition of affinity purified early, middle, late or mature LSU (precursor) particles by semi-quantitative mass spectrometry. The impact of yeast LSU r-proteins rpL25, rpL2, rpL43, and rpL21 on the composition of intermediate to late nuclear LSU precursors was analyzed in more detail. Effects of these proteins on the assembly states of other r-proteins and on the transient LSU precursor association of several ribosome biogenesis factors, including Nog2, Rsa4 and Nop53, are discussed. 相似文献
56.
Quero Gastón Bonnecarrère Victoria Simondi Sebastián Santos Jorge Fernández Sebastián Gutierrez Lucía Garaycochea Silvia Borsani Omar 《Photosynthesis research》2021,150(1-3):97-115
Photosynthesis Research - The photosynthesis process is determined by the intensity level and spectral quality of the light; therefore, leaves need to adapt to a changing environment. The incident... 相似文献
57.
Christophe J. Queval Antony Fearns Laure Botella Alicia Smyth Laura Schnettger Morgane Mitermite Esen Wooff Bernardo Villarreal-Ramos Waldo Garcia-Jimenez Tiaan Heunis Matthias Trost Dirk Werling Francisco J. Salguero Stephen V. Gordon Maximiliano G. Gutierrez 《PLoS pathogens》2021,17(3)
The Mycobacterium tuberculosis complex (MTBC) is a group of related pathogens that cause tuberculosis (TB) in mammals. MTBC species are distinguished by their ability to sustain in distinct host populations. While Mycobacterium bovis (Mbv) sustains transmission cycles in cattle and wild animals and causes zoonotic TB, M. tuberculosis (Mtb) affects human populations and seldom causes disease in cattle. The host and pathogen determinants underlying host tropism between MTBC species are still unknown. Macrophages are the main host cell that encounters mycobacteria upon initial infection, and we hypothesised that early interactions between the macrophage and mycobacteria influence species-specific disease outcome. To identify factors that contribute to host tropism, we analysed blood-derived primary human and bovine macrophages (hMϕ or bMϕ, respectively) infected with Mbv and Mtb. We show that Mbv and Mtb reside in different cellular compartments and differentially replicate in hMϕ whereas both Mbv and Mtb efficiently replicate in bMϕ. Specifically, we show that out of the four infection combinations, only the infection of bMϕ with Mbv promoted the formation of multinucleated giant cells (MNGCs), a hallmark of tuberculous granulomas. Mechanistically, we demonstrate that both MPB70 from Mbv and extracellular vesicles released by Mbv-infected bMϕ promote macrophage multinucleation. Importantly, we extended our in vitro studies to show that granulomas from Mbv-infected but not Mtb-infected cattle contained higher numbers of MNGCs. Our findings implicate MNGC formation in the contrasting pathology between Mtb and Mbv for the bovine host and identify MPB70 from Mbv and extracellular vesicles from bMϕ as mediators of this process. 相似文献
58.
The effect of pond pollution with lead- and iron-containing alloys on the morphogenesis of brown frog (Rana temporaria), moor frog (Rana arvalis), and common toad (Bufo bufo) tadpoles was studied in simulation experiments. Observations showed that metal particles were ingested by tadpoles and produced a significant effect on their body dimensions. Tadpoles developing in water polluted with iron had an increased body size, while lead pollution resulted in retarded growth of tadpoles, and they were significantly smaller than in the control group. However, water pollution with metal alloys had no effect on the proportionality of their development. 相似文献
59.
Jazmin M. Pérez-Rojas Cristino Cruz Patricia García-López Dolores J. Sánchez-González Claudia M. Martínez-Martínez Gisela Ceballos 《Free radical research》2013,47(11):1122-1132
Cisplatin (CDDP) is a chemotherapeutic agent that produces nephrotoxicity associated with oxidative/nitrosative stress. α-Mangostin (α-M) is a xanthone extracted from mangosteen with antioxidant and anti-inflammatory properties. The purpose of this study was to evaluate the renoprotective effect of α-M on the CDDP-induced nephrotoxicity. α-M was administered (12.5 mg/kg/day, i.g.) for 10 days (7 days before and 3 days after CDDP injection). On day 7, rats were treated with a single injection of CDDP (7.5 mg/Kg, i.p.); 3 days after the rats were killed. α-M attenuated renal dysfunction, structural damage, oxidative/nitrosative stress, decrease in catalase expression and increase in mRNA levels of tumour necrosis factor alpha and transforming growth factor beta. In conclusion the renoprotective effect of α-M on CDDP-induced nephrotoxicity was associated with the attenuation in oxidative/nitrosative stress and inflammatory and fibrotic markers and preservation of catalase activity. 相似文献
60.
Everton Falcão de Oliveira Carlos Eurico dos Santos Fernandes Elaine Araújo e Silva Reginaldo Peçanha Brazil Alessandra Gutierrez de Oliveira 《Journal of vector ecology》2013,38(2):224-228
The life cycle of vectors and the reservoirs that participate in the chain of infectious diseases have a strong relationship with the environmental dynamics of the ecosystems in which they live. Oscillations in population abundance and seasonality of insects can be explained by factors inherent in each region and time period. Therefore, knowledge of the relationship and influence of environmental factors on the population of Lutzomyia longipalpis is necessary because of the high incidence of visceral leishmaniasis (VL) in Brazil. This study evaluates the influence of abiotic variables on the population density and seasonal behavior of L. longipalpis in an urban endemic area of VL in Brazil. The sand fly captures were performed every two months between November, 2009 and November, 2010 in the peridomicile of 13 randomly selected residences. We captured 1,367 specimens of L. longipalpis, and the ratio of male/female flies was 2.86:1. The comparison of the total male specimens in the two seasons showed a statistical difference in the wet season, but there was no significant difference when considering the total females. With respect to climatic variables, a significant negative association was observed only with wind speed. During periods of high wind speeds, the population density of this vector decreased. The presence of L. longipalpis was found in all months of the study with bimodal behavior and population peaks during the wet season. 相似文献