全文获取类型
收费全文 | 13417篇 |
免费 | 810篇 |
国内免费 | 7篇 |
出版年
2023年 | 116篇 |
2022年 | 126篇 |
2021年 | 225篇 |
2020年 | 206篇 |
2019年 | 217篇 |
2018年 | 325篇 |
2017年 | 331篇 |
2016年 | 474篇 |
2015年 | 554篇 |
2014年 | 630篇 |
2013年 | 874篇 |
2012年 | 984篇 |
2011年 | 933篇 |
2010年 | 578篇 |
2009年 | 515篇 |
2008年 | 696篇 |
2007年 | 650篇 |
2006年 | 650篇 |
2005年 | 561篇 |
2004年 | 550篇 |
2003年 | 484篇 |
2002年 | 460篇 |
2001年 | 237篇 |
2000年 | 184篇 |
1999年 | 164篇 |
1998年 | 95篇 |
1997年 | 88篇 |
1996年 | 66篇 |
1995年 | 71篇 |
1994年 | 63篇 |
1993年 | 62篇 |
1992年 | 109篇 |
1991年 | 85篇 |
1990年 | 103篇 |
1989年 | 114篇 |
1988年 | 96篇 |
1987年 | 65篇 |
1986年 | 88篇 |
1985年 | 103篇 |
1983年 | 63篇 |
1982年 | 61篇 |
1979年 | 92篇 |
1978年 | 64篇 |
1977年 | 59篇 |
1974年 | 83篇 |
1973年 | 78篇 |
1970年 | 69篇 |
1969年 | 65篇 |
1968年 | 61篇 |
1967年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
991.
992.
Gülay Bayramoğlu Meral Karakışla Begum Altıntaş Ayşegül U. Metin Mehmet Saçak M. Yakup Arıca 《Process Biochemistry》2009,44(8):880-885
Polyacylonitrile fibers (PAN) surfaces were modified with chemical polymerization of conductive polyaniline (PANI) in the presence of potassium dichromate as an oxidizing agent. The effect of aniline concentration on the grafting efficiency and on the electrical surface resistance of PAN/PANI composite fibers was investigated. The surface resistance of the conductive composite fibers in this work was found to be between 8.0 and 0.5 kΩ/cm. As the amount of grafted PANI increased on the PAN fibers the electrical resistance of composite fibers decreased. The PAN/PANI composite fibers were characterized by SEM and FTIR studies. Composite PAN/PANI fibers were used for reversible immobilization of invertase. The immobilization efficiency and the activity of the immobilized invertase (from 1.0 mg/mL invertase solution at pH 5.5) were increased with increasing PANI contents of the composite fibers. The maximum amount of immobilized enzyme onto composite fibers containing 2.0% PANI was about 76.6 mg/g. The optimum pH for the free enzyme was observed at 5.0. On the other hand, immobilized invertase yielded a broad optimum pH profile between pH 5.0 and 7.0. Immobilized invertase exhibited 83% of its original activity even after two months storage at 4 °C while the free enzyme showed only 7% of its initial activity. 相似文献
993.
N. André Sasaki Maria Concepcion Garcia-Alvarez Qian Wang Ludmila Ermolenko Gisèle Franck Naïma Nhiri Marie-Thérèse Martin Nicolas Audic Pierre Potier 《Bioorganic & medicinal chemistry》2009,17(6):2310-2320
2,3-Diaminopropionic acid (Dap) and N-terminal Dap peptides have been found to inhibit in vitro protein-modifications by methylglyoxal (MG), one of the highly reactive α-dicarbonyl compounds. MG scavenging potency of the newly synthesized N-terminal Dap peptides is demonstrated by RP-HPLC, SDS–PAGE and non-denaturing PAGE analysis, assays for enzymatic activity and cell viability study and was compared with that of known AGE inhibitors, such as aminoguanidine, pyridoxamine, metformin and carnosine. Two addition products of MG and l-Dap-l-Leu are separated by HPLC and their chemical structures are characterized by 1H and 13C NMR spectroscopy to indicate that both of them are pyrazines derived from 2 molecules of MG and 1 molecule of l-Dap-l-Leu. Mutagenic activities of l-Dap-l-Leu and l-Dap-l-Val and their metabolites according to the Ames assay are found to be negative. 相似文献
994.
Vanessa Moreira José María Gutiérrez Rafaela Bacci Amaral Stella Regina Zamunér Catarina de Fátima Pereira Teixeira 《Prostaglandins, leukotrienes, and essential fatty acids》2009,80(2-3):107-114
In this study, the ability of Bothrops asper snake venom (BaV) to increase the production of prostaglandins PGE2 and PGD2 was assessed in a mouse model in vivo and in inflammatory cells in vitro. In addition, the expressions of COX-1 and COX-2 were assessed. BaV induced an increment in the in vivo synthesis of PGE2 and PGD2, together with an enhanced expression of COX-2, but not of COX-1. However, enzymatic activities of COX-1 and COX-2 were increased. Incubation of isolated macrophages and neutrophils with a sub-cytotoxic concentration of BaV in vitro resulted in increased release of PGE2 and PGD2 by macrophages and PGE2 by neutrophils, concomitantly with an increment in the expression of COX-2, but not of COX-1 by both cell types. Our results demonstrate the ability of BaV to promote the expression of COX-2 and to induce the synthesis of proinflammatory prostaglandins. Macrophages and neutrophils may be important targets for this venom under in vivo situation. 相似文献
995.
Ahmet Yesildağ Ahmet Özden H. Ramazan Yılmaz Efkan Uz Yetkin Ağackıran Mihrican Yesildağ Nigar Yılmaz Rana Sırmalı Hüseyin Vural Mustafa Nazıroğlu 《Cell biochemistry and function》2009,27(3):142-147
It has been suggested that reactive oxygen species (ROS) plays an important role in radio contrast media (RCM)‐induced ischemia reperfusion tissue injury although antioxidants may have protective effects on the injury. We investigated the effects of erdosteine as an antioxidant agent on RCM‐induced liver toxicity in rats by evaluation of lipid peroxidation (as TBARS), catalase (CAT), superoxide dismutase (SOD), reduced glutathione (GSH) and glutathione peroxidase (GSH‐Px) values and histological evaluation. Twenty‐one rats were equally divided into three groups as follows: control, RCM, and RCM plus erdosteine. RCM was intraperitoneally administered for 1 day. Erdosteine was administered orally for 2 days after RCM administration. Liver samples were taken from the rats and they homogenized in a motor‐driven tissue homogenizer. TBARS levels were significantly (p < 0.005) higher in RCM group than in control although SOD activities significantly (p < 0.05) decreased in RCM group. TBARS levels were lower in RCM plus erdosteine group than in control although SOD activity and GSH level increased (p < 0.05) in liver as compared to RCM alone. Erdosteine showed also histopathological protection (p < 0.0001) against RCM induced hepatotoxicity. GSH‐Px and CAT activities were not statistically changed by the erdosteine. According to our results, it can be concluded that radiocontrast media can induce oxidative stress in liver as suggested by previous studies. Erdosteine seems to be protective agent on the radiocontrast media‐induced liver toxicity by inhibiting the production of ROS via the enzymatic antioxidant system. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
996.
Uyar Basar Gürgan Muazzez Özgür Ebru Gündüz Ufuk Yücel Meral Eroglu Inci 《Bioprocess and biosystems engineering》2015,38(10):1935-1942
Bioprocess and Biosystems Engineering - Photofermentative production of hydrogen is a promising and sustainable process; however, it should be coupled to dark fermentation to become cost effective.... 相似文献
997.
Şahin Burcu Öztürk Sibel Çalık Pınar Özdamar Tunçer H. 《Bioprocess and biosystems engineering》2015,38(10):1855-1865
Bioprocess and Biosystems Engineering - Defined and semi-defined medium-based feeding strategies were developed to enhance recombinant human growth hormone (rhGH) production by Bacillus subtilis... 相似文献
998.
Absolute quantification of dengue virus serotype 4 chimera vaccine candidate in Vero cell culture by targeted mass spectrometry
下载免费PDF全文
![点击此处可从《Proteomics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Romain Carrière Jordane Biarc Catherine Fonbonne Arnaud Salvador Céline Huillet Yves Berard Olivier Adam Catherine Manin Jérôme Lemoine 《Proteomics》2015,15(19):3320-3330
Infection by dengue flavivirus is transmitted by mosquitoes and affects tens to hundreds of millions people around the world each year. Four serotypes have been described, all of which cause similar disease. Currently, there no approved vaccines or specific therapeutics for dengue, although several vaccine prototypes are in different stages of clinical development. Among them, a chimeric vaccine, built from the replication machinery of the yellow fever 17D virus, has shown promising results in phase III trials. Accurate quantitation of expressed viral particles in alive attenuated viral antigen vaccine is essential and determination of infectious titer is usually the method of choice. The current paper describes an alternative or orthogonal strategy, namely, a multiplexed and absolute assay of four proteins of the chimera yellow fever/dengue serotype 4 virus using targeted MS in SRM mode. Over 1 month, variability of the assay using a partially purified Vero cell extract was between 8 and 17%, and accuracy was between 80 and 120%. In addition, the assay was linear between 6.25 and 200 nmol/L and could therefore be used in the near future to quantify dengue virus type 4 during production and purification from Vero cells. 相似文献
999.
1000.
Muhamad Hafiz Abd Rahim Hanan Hasan Alejandro Montoya Ali Abbas 《Engineering in Life Science》2015,15(2):220-228
The use of pure substrate represents a significant proportion of the cost of manufacturing a drug such as lovastatin. This study explores the production of lovastatin and (+)‐geodin by Aspergillus terreus ATCC 20542 using biodiesel‐derived crude glycerol (CG) as a feedstock. Shake flask experiments showed reduced lovastatin production and glycerol consumption in the presence of 10–50 g/L CG with respect to pure glycerol controls. At 50 g/L, lovastatin and (+)‐geodin production was significantly reduced by 82 and 73%, respectively. The lowest lovastatin inhibition was detected in 30 g/L of CG (48%), which was accompanied by a significant rise in (+)‐geodin production (338%). Further investigation was performed on three major impurities found in CG, namely methanol (MeOH), sodium chloride (NaCl), and fatty acids (oleic acid and palmitic acid (PA), soap). None was particularly inhibitory for lovastatin, except soap and PAs, which reduced its production by more than 50% at all concentrations tested. In contrast, (+)‐geodin was inhibited in the presence of MeOH and PA by up to 46 and 91%, respectively. These observations indicate that partial purification of CG would be potentially useful in improving production of lovastatin and (+)‐geodin by A. terreus. 相似文献