全文获取类型
收费全文 | 1012篇 |
免费 | 55篇 |
国内免费 | 1篇 |
出版年
2024年 | 3篇 |
2022年 | 20篇 |
2021年 | 37篇 |
2020年 | 29篇 |
2019年 | 28篇 |
2018年 | 27篇 |
2017年 | 28篇 |
2016年 | 29篇 |
2015年 | 49篇 |
2014年 | 56篇 |
2013年 | 71篇 |
2012年 | 71篇 |
2011年 | 85篇 |
2010年 | 47篇 |
2009年 | 27篇 |
2008年 | 55篇 |
2007年 | 51篇 |
2006年 | 45篇 |
2005年 | 49篇 |
2004年 | 28篇 |
2003年 | 29篇 |
2002年 | 25篇 |
2001年 | 5篇 |
2000年 | 10篇 |
1999年 | 13篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 8篇 |
1973年 | 6篇 |
1972年 | 3篇 |
排序方式: 共有1068条查询结果,搜索用时 171 毫秒
991.
Wastewater that enters wastewater treatment plants contains lots of pathogenic and nonpathogenic microorganisms which can become bioaerosols during treatment processes and pose health hazard to workers and nearby residents. The emission of the bioaerosols from an urban wastewater treatment plant in spring and summer in different locations and downwind of the plant adopting an extended mechanical aeration system was investigated. Samples of bacteria and fungi were collected within 6 months at 10 selected points by an Anderson one-stage impactor. The highest concentration of bacteria (mean 1373 CFU/m3, 741–2817 CFU/m3) and fungi (mean 1384 CFU/m3, 212–1610 CFU/m3) was found in downwind of the aeration basins. Statistical analysis showed a significant relationship between concentration of bacterial bioaerosols at downwind side of the aeration basins and wind speed (p value <0.05) and temperature (p value <0.05). Also, in the spring and summer, between the number of bacteria and fungi inside the plant and outside the plant (downwind) a significant correlation was observed (p value ≤0.05). The concentrations of bacteria at a distance of 500 m downwind were much higher than those at the background (upwind) point in spring and summer. The processes of wastewater treatment especially using mechanical equipment to create turbulence can be considered as a major source of spreading airborne microorganisms to ambient air of wastewater treatment plants, and the bioaerosols can be dispersed to downwind distances affecting the nearby neighboring. Therefore, in order to decrease the bioaerosols emission, doing some course of actions such as covering the surface of aeration basins, changing the aeration methods and aeration equipment (e. g using diffuser aerator) may be effective. 相似文献
992.
Delivery of dsRNA through topical feeding for RNA interference in the citrus sap piercing‐sucking hemipteran,Diaphorina citri
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)
RNA interference (RNAi) is a powerful means to study functional genomics in insects. The delivery of dsRNA is a challenging step in the development of RNAi assay. Here, we describe a new delivery method to increase the effectiveness of RNAi in the Asian citrus psyllid Diaphorina citri. Bromophenol blue droplets were topically applied to fifth instar nymphs and adults on the ventral side of the thorax between the three pairs of legs. In addition to video recordings that showed sucking of the bromophenol blue by the stylets, dissected guts turned blue indicating that the uptake was through feeding. Thus, we called the method topical feeding. We targeted the abnormal wing disc gene (awd), also called nucleoside diphosphate kinase (NDPK), as a reporter gene to prove the uptake of dsRNA via this method of delivery. Our results showed that dsRNA‐awd caused reduction of awd expression and nymph mortality. Survival and lifespan of adults emerged from treated nymphs and treated adults were affected. Silencing awd caused wing malformation in the adults emerged from treated nymphs. Topical feeding as a delivery of dsRNA is highly efficient for both nymphs and adults. The described method could be used to increase the efficiency of RNAi in D. citri and other sap piercing‐sucking hemipterans. 相似文献
993.
Rachid Essalmani Jaspreet Jain Delia Susan-Resiga Ursula Andro Alexandra Evagelidis Rabeb Mouna Derbali David N. Huynh Frdric Dallaire Mlanie Laporte Adrien Delpal Priscila Sutto-Ortiz Bruno Coutard Claudine Mapa Keith Wilcoxen Etienne Decroly Tram N. Q. Pham ric A. Cohen Nabil G. Seidah 《Journal of virology》2022,96(13)
994.
Ana Rubia-Soria Hikmate Abriouel Rosario Lucas Nabil Ben Omar Magdalena Martínez-Cañamero Antonio Gálvez 《World journal of microbiology & biotechnology》2006,22(7):765-768
Summary The production of antimicrobial substances was studied among 195 bacterial isolates from retail table olives. A total 86 isolates
tested positive, and they clustered in 10 groups according to their inhibitory spectra. Many isolates (38.37%) produced strong
inhibition against all bacteria tested (Listeria innocua, Lactococcus lactis, Bacillus cereus, B. megaterium, Staphylococcus aureus, Micrococcus luteus, Enterococcus
faecalis, and Escherichia coli). The selected bacterial isolates were Gram-positive bacteria with rod morphology (62.67%), short rods (26.65%) or cocci
(10.67%). Isolates producing antimicrobial substances may be useful as starters to enhance control of table olive fermentation
and improve the safety of retail table olives. 相似文献
995.
Rousselet E Marcinkiewicz J Kriz J Zhou A Hatten ME Prat A Seidah NG 《Journal of lipid research》2011,52(7):1383-1391
Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a major role in cholesterol homeostasis through enhanced degradation of the LDL receptor (LDLR) in liver. As novel inhibitors/silencers of PCSK9 are now being tested in clinical trials to treat hypercholesterolemia, it is crucial to define the physiological consequences of the lack of PCSK9 in various organs. LDLR regulation by PCSK9 has not been extensively described during mouse brain development and injury. Herein, we show that PCSK9 and LDLR are co-expressed in mouse brain during development and at adulthood. Although the protein levels of LDLR and apolipoprotein E (apoE) in the adult brain of Pcsk9(-/-) mice are similar to those of wild-type (WT) mice, LDLR levels increased and were accompanied by a reduction of apoE levels during development. This suggests that the upregulation of LDLR protein levels in Pcsk9(-/-) mice enhances apoE degradation. Upon ischemic stroke, PCSK9 was expressed in the dentate gyrus between 24 h and 72 h following brain reperfusion. Although mouse behavior and lesion volume were similar, LDLR protein levels dropped ~2-fold less in the Pcsk9(-/-)-lesioned hippocampus, without affecting apoE levels and neurogenesis. Thus, PCSK9 downregulates LDLR levels during brain development and following transient ischemic stroke in adult mice. 相似文献
996.
In Saccharomyces cerevisiae, replication stress induced by hydroxyurea (HU) and methyl methanesulfonate (MMS) activates DNA integrity checkpoints; in checkpoint-defective yeast strains, HU treatment also induces morphological aberrations. We find that the sphingolipid pathway gene ISC1, the product of which catalyzes the generation of bioactive ceramides from complex sphingolipids, plays a novel role in determining cellular morphology following HU/MMS treatment. HU-treated isc1Δ cells display morphological aberrations, cell-wall defects, and defects in actin depolymerization. Swe1, a morphogenesis checkpoint regulator, and the cell cycle regulator Cdk1 play key roles in these morphological defects of isc1Δ cells. A genetic approach reveals that ISC1 interacts with other checkpoint proteins to control cell morphology. That is, yeast carrying deletions of both ISC1 and a replication checkpoint mediator gene including MRC1, TOF1, or CSM3 display basal morphological defects, which increase following HU treatment. Interestingly, strains with deletions of both ISC1 and the DNA damage checkpoint mediator gene RAD9 display reduced morphological aberrations irrespective of HU treatment, suggesting a role for RAD9 in determining the morphology of isc1Δ cells. Mechanistically, the checkpoint regulator Rad53 partially influences isc1Δ cell morphology in a dosage-dependent manner. 相似文献
997.
Cardioprotection by Cu, Zn-superoxide dismutase is lost at high doses in the reoxygenated heart 总被引:1,自引:0,他引:1
Bassam A. Omar Nabil M. Gad Maria C. Jordan Scott P. Striplin William J. Russell James M. Downey Joe M. McCord 《Free radical biology & medicine》1990,9(6):465-471
Limited dose-response curves for superoxide dismutase (SOD) were assessed in isolated and in vivo hearts. SOD at 2.3, 7, 20, or 50 mg/L suppressed CK release in Langendorff rat hearts by 61%, 63%, 72%, and 30%, respectively. SOD at 0.5, 1, 5, and 50 mg/L suppressed LDH release in Langendorff rabbit hearts by 32%, 48%, 54%, and −12%, respectively. In rabbit hearts subjected to coronary artery ligation and reperfusion in vivo, SOD at 2, 5,or 15 mg/kg reduced infarct size by 10%, 30% or 19%, respectively, while 50 mg/kg increased infarct size by 28%. In conclusion, while SOD was protective at low doses in all models, protection was lost at higher doses in the isolated rat and rabbit hearts, and exacerbation of damage was seen in the in vivo rabbit hearts. 相似文献
998.
Upregulation of the expression of the LDL receptor (LDLR) gene does not always lead to an increase in the LDLR protein. While the mRNA expression of the LDLR and the newly studied proprotein convertase PCSK9 are coordinately upregulated in absence of sterols, the latter proteinase apparently enhances the degradation of the LDLR protein. 相似文献
999.
1000.