全文获取类型
收费全文 | 1103篇 |
免费 | 50篇 |
出版年
2023年 | 15篇 |
2022年 | 16篇 |
2021年 | 35篇 |
2020年 | 21篇 |
2019年 | 27篇 |
2018年 | 34篇 |
2017年 | 26篇 |
2016年 | 35篇 |
2015年 | 54篇 |
2014年 | 51篇 |
2013年 | 88篇 |
2012年 | 88篇 |
2011年 | 79篇 |
2010年 | 46篇 |
2009年 | 37篇 |
2008年 | 56篇 |
2007年 | 47篇 |
2006年 | 44篇 |
2005年 | 42篇 |
2004年 | 36篇 |
2003年 | 28篇 |
2002年 | 19篇 |
2001年 | 19篇 |
2000年 | 15篇 |
1999年 | 17篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 16篇 |
1991年 | 12篇 |
1990年 | 11篇 |
1989年 | 16篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 4篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1979年 | 8篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1975年 | 5篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1966年 | 3篇 |
排序方式: 共有1153条查询结果,搜索用时 31 毫秒
981.
S. Ravi Kiran P. Sita Devi K. Janardhan Reddy 《World journal of microbiology & biotechnology》2008,24(9):1909-1914
The essential oils obtained by hydrodistillation of leaves and stems of Chloroxylon swietenia DC. were analysed by GC and GC-MS. The main components in the leaf oil were limonene, pregeijerene, geijerene and germacrene
D, while stem oil was rich in limonene, methyl eugenol, pregeijerene and geijerene. The essential oils were evaluated for
antimicrobial activity against two gram-positive and two gram-negative bacteria and four pathogenic fungi using agar disc
diffusion technique. Subsequently, the minimum inhibitory concentration (MIC) from oils was determined by broth microdilution.
Both the oils exhibited moderate to strong activities against all the organisms tested. Bacillus subtilis was most susceptible at 100 μg/ml of leaf and stem oils with inhibition zones of 15.9 and 13.1 mm respectively. Among all
the fungi tested, A. niger inhibited effectively with a zone of inhibition of 14.9 and 11.5 mm for leaf and stem oils respectively. The results obtained
suggest that the essential oils of the plant possess antimicrobial properties and serve as a biofriendly source of antimicrobial
ingredients for the food and pharmaceutical industries. 相似文献
982.
The aim of this study was the assessment of reduction of chemical oxygen demand (COD) and biological oxygen demand (BOD) of wastewater from coffee processing plant using activated carbon made up of Avacado Peels. The complete study was done in batch mode to investigate the effect of operating parameters. The results of the COD and BOD concentration reduction with avocado peel carbon (APC) and commercial activated carbon (CAC) were compared and optimum operating conditions were determined for maximum reduction. Adsorption isotherm was also studied besides the calculation of optimum treatment parameters for maximum reduction of COD and BOD concentration from effluent of the coffee processing plant. The maximum percentage reduction of COD and BOD concentration under optimum operating conditions using APC was 98.20% and 99.18% respectively and with CAC this reduction was 99.02% and 99.35% respectively. As the adsorption capacity of APC is comparable with that of CAC for reduction of COD and BOD concentration, it could be a lucrative technique for treatment of domestic wastewater generated in decentralized sectors. 相似文献
983.
In the present study, sludge sample from biological treatment plant of a textile industry was acclimatized for decolourization of azo dye Direct Black 38 (DB38). A continuous culture experiment showed that the acclimatized sludge could decolourize 76% of 100mg/l DB38. Bacterial community in the sludge was analyzed using culture-independent molecular approach to get the complete picture of its diversity. RFLP analysis of its 16S rRNA gene library divided the clones into 14 distinct groups. Phylogenetic analysis of these groups showed that they belonged to five different bacterial lineages: beta- and gamma-Proteobacteria (3 and 4 respectively), Bacteroidetes (2), Firmicutes (4) and Actinobacteria (1). The largest number of clones was found to cluster in the gamma-Proteobacteria (54%), followed by Firmicutes (19%), beta-Proteobacteria (14%), Bacteroidetes (10%) and Actinobacteria (3%). 相似文献
984.
Singh OM Singh SJ Devi MB Devi LN Singh NI Lee SG 《Bioorganic & medicinal chemistry letters》2008,18(24):6462-6467
Copper (II) chloride in the absence of any solvent, efficiently catalyses the synthesis of dihydropyrimidinones (80-96% yields) by the Biginelli reaction. Six compounds were selected and examined their antifungal activities against the radial growth of three fungal species viz., Trichoderma hammatum, Trichoderma koningii and Aspergillus niger. 相似文献
985.
986.
Devi Kamakshi P. Raj Yogeeswaran Ganesa 《World journal of microbiology & biotechnology》1999,15(2):223-229
Bacterial isolates from Tapioca cultivar soil were systematically identified. The effect of culture conditions and medium components on the production of extracellular amylase and pullulanase by Micrococcus halobius OR-1 were investigated. Amylase and pullulanase activity in the cell-free supernatant reached a maximum of 8.6 U/ml and 4.8 U/ml after 48 h, respectively. The enzyme converted the complex polysaccharides starch, dextrin, pullulan, amylose and amylopectin predominantly into maltotriose. Saccharification of 15% cereal, tuber starches and root starches with the whole cultured cells (WCC) or cell-free supernatant (CFS) showed comparable and complete saccharification within 90 min. These saccharifying enzymes had a pH optimum of 8.0 and were stable over a broad pH range of 6–12. Thus the coexpressed physicochemically compatible extracellular amylase and pullulanase produced by the Micrococcus halobius OR-1 strain might have important value in the enzyme-based starch saccharification industry. 相似文献
987.
Stuart-Fox D 《Trends in ecology & evolution》2005,20(10):521-523
Deceptive signals are a challenge to explain because on average, signals should be reliable. When being deceived is costly to the receiver, a coevolutionary struggle between senders and receivers can ensue. Recent work by Macías Garcia and Ramirez raises the intriguing possibility that through such a coevolutionary process, cheats can become honest. 相似文献
988.
Bhatia M Ramnath RD Chevali L Guglielmotti A 《American journal of physiology. Gastrointestinal and liver physiology》2005,288(6):G1259-G1265
Chemokines are believed to play a key role in the pathogenesis of acute pancreatitis. We have earlier shown that pancreatic acinar cells produce the chemokine monocyte chemotactic protein (MCP)-1 in response to caerulein hyperstimulation, demonstrating that acinar-derived MCP-1 is an early mediator of inflammation in acute pancreatitis. Blocking chemokine production or action is a major target for pharmacological intervention in a variety of inflammatory diseases, such as acute pancreatitis. 2-Methyl-2-[[1-(phenylmethyl)-1H-indazol-3yl]methoxy]propanoic acid (bindarit) has been shown to preferentially inhibit MCP-1 production in vitro in monocytes and in vivo without affecting the production of the cytokines IL-1, IL-6, or the chemokines IL-8, protein macrophage inflammatory-1alpha, and RANTES. The present study aimed to define the role of MCP-1 in acute pancreatitis with the use of bindarit. In a model of acute pancreatitis induced by caerulein hyperstimulation, prophylactic as well as therapeutic treatment with bindarit significantly reduced MCP-1 levels in the pancreas. Also, this treatment significantly protected mice against acute pancreatitis as evident by attenuated hyperamylasemia neutrophil sequestration in the pancreas (pancreatic MPO activity), and pancreatic acinar cell injury/necrosis on histological examination of pancreas sections. 相似文献
989.
The DNA sequences encompassing two hypervariable regions, VD II and III of the 56 kDa immunodominant protein gene of 21 Malaysian strains of Orientia tsutsugamushi were determined. Two strains demonstrated a 100% DNA homology with the Gilliam prototype strain, and one with TH1817 strain and TA678 strain respectively. High percentages of DNA similarity (95-99%) were observed with Karp (4 strains), Gilliam (2 strains), TH1817 (4 strains), TC586 (3 strains) and TA763 (1 strain). The remaining strains demonstrated the highest DNA similarity with TA763 (1 strain, 89%), TA678 (1 strain, 86%) and TA686 (1 strain, 87%). Our study provides additional evidence on the existence and the genetic heterogeneity of TA strains of the Southeast Asia and their closely related strains in Malaysia. 相似文献
990.
Reactive oxygen species (ROS) have pathogenic effects on ischemic-reperfusion injury of heart. Hence, it is important to identify natural antioxidative agents to mitigate such effects. Recently, it has been reported that Clerodendron colebrookianum (CC) leaf extract has antioxidant and hypolipidemic effects in experimental animals. The aim of this study was to examine whether acute treatment with CC extract offers protection against ischemic-reperfusion injury (IRI) and IRI-induced changes in endogenous antioxidant enzyme activities of rat heart. Isolated rat hearts were perfused using the Langendorff's technique, and 20 min of global ischemia was followed by 40 min of reperfusion. Lipid peroxidation after the ischemic-reperfusion episode was significantly reduced in the CC extract-treated heart compared to the control group and suppressed the leakage of lactate dehydrogenase (LDH) during reperfusion. Moreover, CC extract diminished the depletion of myocardial antioxidant enzymes (SOD, Catalase, GSH and GPx) after ischemia-reperfusion. Furthermore, IRI-induced cellular damage was significantly less in CC extract treated myocytes. These results indicate that CC leaf extract protects against oxidative stress and cellular injury associated with ischemic-reperfusion injury of rat heart and suggests that the protective effects of CC extract depend on its antioxidant properties. 相似文献