首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1151篇
  免费   49篇
  国内免费   1篇
  2023年   6篇
  2022年   20篇
  2021年   38篇
  2020年   25篇
  2019年   21篇
  2018年   48篇
  2017年   21篇
  2016年   44篇
  2015年   34篇
  2014年   67篇
  2013年   114篇
  2012年   108篇
  2011年   84篇
  2010年   71篇
  2009年   47篇
  2008年   48篇
  2007年   44篇
  2006年   49篇
  2005年   44篇
  2004年   45篇
  2003年   33篇
  2002年   36篇
  2001年   12篇
  2000年   15篇
  1999年   15篇
  1998年   12篇
  1997年   8篇
  1996年   7篇
  1995年   9篇
  1994年   8篇
  1993年   3篇
  1992年   5篇
  1991年   2篇
  1989年   4篇
  1988年   3篇
  1987年   5篇
  1986年   3篇
  1985年   8篇
  1984年   3篇
  1983年   3篇
  1981年   3篇
  1980年   3篇
  1979年   4篇
  1978年   3篇
  1977年   3篇
  1972年   2篇
  1964年   1篇
  1963年   1篇
  1961年   1篇
  1960年   1篇
排序方式: 共有1201条查询结果,搜索用时 15 毫秒
91.

Background

Coronary Artery Disease (CAD) is clearly a multifactorial disease that develops from childhood and ultimately leads to death. Several reports revealed having a First Degree Relatives (FDRS) with premature CAD is a significant autonomous risk factor for CAD development. C - reactive protein (CRP) is a member of the pentraxin family and is the most widely studied proinflammatory biomarker. IL-18 is a pleiotrophic and proinflammatory cytokine which is produced mainly by macrophages and plays an important role in the inflammatory cascade.

Methods and Results

Hs-CRP levels were estimated by ELISA and Genotyping of IL-18 gene variant located on promoter -137 (G/C) by Allele specific PCR in blood samples of 300 CAD patients and 300 controls and 100 FDRS. Promoter Binding sites and Protein interacting partners were identified by Alibaba 2.1 and Genemania online tools respectively. Hs-CRP levels were significantly high in CAD patients followed by FDRS when compared to controls. In IL-18 -137 (G/C) polymorphism homozygous GG is significantly associated with occurrence of CAD and Hs-CRP levels were significantly higher in GG genotype subjects when compared to GC and CC. IL-18 was found to be interacting with 100 protein interactants.

Conclusion

Our results indicate that Hs-CRP levels and IL-18-137(G/C) polymorphism may help to identify risk of future events of CAD in asymptomatic healthy FDRS.  相似文献   
92.
Regrowth of plants after cryopreservation varies, and resulting regrowth ranges from poor to excellent. Oxidative stress is a potential cause of damage in plant tissues. Antioxidants and anti-stress compounds may improve regrowth by preventing or repairing the damage. Lipoic acid (LA), glutathione (GSH), glycine betaine (GB), and polyvinylpyrrolidone (PVP) were tested during cryopreservation of shoot tips using the plant vitrification solution 2 (PVS2) protocol. Two in vitro-grown blackberry cultivars were cold acclimated and then cryopreserved in liquid nitrogen (LN). The antioxidant and anti-stress compounds were added at four critical steps of the protocol: pretreatment, loading, rinsing, and regrowth. Three out of the four compounds significantly improved regrowth of cryopreserved shoot tips. Regrowth ranged from 40% to 50% for controls to >80% for treated shoot tips. LA (4-8 mM) produced high regrowth at pretreatment, loading, and rinsing for ‘Chehalem’ and at all steps for ‘Hull Thornless’. Recovery improved at all steps with GSH (0.16 mM) and GB (10 mM). PVP had a neutral or negative impact on regrowth. Overall addition of LA, GSH, and GB improved regrowth by ∼25% over the shoot tips cryopreserved using the regular PVS2 protocol (control). This study shows that adding non-vitamin antioxidants and anti-stress compounds during the PVS2-vitrification protocol improves regrowth of shoot cultures following cryopreservation. We recommend inclusion of antioxidants as part of standard cryopreservation protocols.  相似文献   
93.
8,8-Diphenyl-2,3,4,8-tetrahydroimidazo[1,5-a]pyrimidin-6-amine (1) was identified through HTS, as a weak (micromolar) inhibitor of BACE1. X-Ray crystallographic studies indicate the 2-aminoimidazole ring forms key H-bonding interactions with Asp32 and Asp228 in the catalytic site of BACE1. Lead optimization using structure-based focused libraries led to the identification of low nanomolar BACE1 inhibitors such as 20b with substituents which extend from the S1 to the S3 pocket.  相似文献   
94.
Biomass feedstock having less competition with food crops are desirable for bio-ethanol production and such resources may not be localized geographically. A distributed production strategy is therefore more suitable for feedstock like water hyacinth with a decentralized availability. In this study, we have demonstrated the suitability of this feedstock for production of fermentable sugars using cellulases produced on site. Testing of acid and alkali pretreatment methods indicated that alkali pretreatment was more efficient in making the sample susceptible to enzyme hydrolysis. Cellulase and β-glucosidase loading and the effect of surfactants were studied and optimized to improve saccharification. Redesigning of enzyme blends resulted in an improvement of saccharification from 57% to 71%. A crude trial on fermentation of the enzymatic hydrolysate using the common baker’s yeast Saccharomyces cerevisiae yielded an ethanol concentration of 4.4 g/L.  相似文献   
95.
A bioassay-guided fractionation and chemical examination of chloroform extract of Plumbago capensis roots resulted in isolation and characterization of two new napthaquinone derivatives (4, 8) along with six known compounds (13, 57). Their structures were determined on the basis of extensive spectroscopic (IR, MS, 1D and 2D NMR) data analysis and by comparison with the literature data. All the compounds were tested for their mosquito larvicidal activity against fourth instar larvae of Aedes aegypti, and compared with that of rotenone. Among the tested compounds, isoshinanolone (3) and plumbagin (1) showed excellent toxicity with LC50 values of 1.26 and 5.43 μg/mL. New compound (8) displayed moderate toxicity against the tested mosquito species.  相似文献   
96.
Mutations in PTPN11 gene was responsible for ~50% of the Noonan syndrome (NS), however, we did not find any mutation in PTPN11 in any of seven NS patients analysed. Whereas, the complete mtDNA sequencing revealed 146 mutations, of which five, including one heteroplasmic (A11144R; Thr  Ala) non-synonymous mutation, were novel and exclusively observed in NS patients. Interestingly all the seven probands and their maternal relatives were clustered under a major haplogroup R and its novel sub-haplogroups (R7b1b, R30a1, R30c, T2b7, U9a1) exclusive in NS, therefore we strongly suggest that these haplogroups may influence NS in South Indian populations.  相似文献   
97.
Peste des Petits Ruminants (PPR) is a highly contagious animal disease caused by the Peste des Petits Ruminants virus (PPRV) belonging to the genus morbillivirus and family Paramyxoviridae. The disease results in high morbidity and mortality in goats, sheep and in some small wild ruminants. The presence of large number of small ruminants reared in endemic areas makes PPR a notorious disease threatening the livelihood of poor farmers. Conventional vaccination using a live, attenuated vaccine gives adequate protection but cannot be used in case of eradication of the disease due to difficulty in differentiation of infected animals from the vaccinated ones.  相似文献   
98.
99.
100.
The present study was directed to the production of N-acetyl-D-glucosamine using endochitinase and chitobiase from fungal cultures in solid culturing. Fifteen fungal strains were evaluated for endochitinase and chitobiase production under solid-state fermentation using agro-industrial residues, of which Penicillium aculeatum NRRL 2129 showed maximum endochitinase activity whereas Trichoderma harzianum TUBF 927 showed maximum chitobiase activity. Eleven substrates, alone and in combination with chitin, were evaluated for the enzyme production. Optimization of physico-chemical parameters such as incubation period and initial moisture content, and nutritional parameters such as chitin source, inorganic and organic nitrogen sources, were carried out. Optimization resulted in more than 3-fold increase in endochitinase production (from 3.5 to 12.53 U/g dry weight of substrate) and about 1.5-fold increase in chitobiase production (from 1.6 to 2.25 U/g dry weight of substrate). Studies on the degradation of colloidal chitin to N-acetyl-D-glucosamine showed improved efficiency when endochitinase and chitobiase were used in combination.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号