全文获取类型
收费全文 | 1631篇 |
免费 | 69篇 |
国内免费 | 1篇 |
专业分类
1701篇 |
出版年
2023年 | 24篇 |
2022年 | 34篇 |
2021年 | 63篇 |
2020年 | 42篇 |
2019年 | 31篇 |
2018年 | 52篇 |
2017年 | 47篇 |
2016年 | 59篇 |
2015年 | 62篇 |
2014年 | 87篇 |
2013年 | 143篇 |
2012年 | 130篇 |
2011年 | 113篇 |
2010年 | 67篇 |
2009年 | 54篇 |
2008年 | 84篇 |
2007年 | 78篇 |
2006年 | 72篇 |
2005年 | 60篇 |
2004年 | 53篇 |
2003年 | 54篇 |
2002年 | 46篇 |
2001年 | 15篇 |
2000年 | 14篇 |
1999年 | 18篇 |
1998年 | 9篇 |
1997年 | 10篇 |
1996年 | 12篇 |
1995年 | 5篇 |
1994年 | 14篇 |
1993年 | 11篇 |
1992年 | 9篇 |
1991年 | 5篇 |
1990年 | 9篇 |
1988年 | 8篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1979年 | 7篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1971年 | 5篇 |
1970年 | 4篇 |
1969年 | 5篇 |
1966年 | 3篇 |
排序方式: 共有1701条查询结果,搜索用时 15 毫秒
21.
Endom Ismail Omimah Khaled Jaber Nofal Rajalingham Sakthiswary Syahrul Sazliyana Shaharir Radhika Sridharan 《PloS one》2016,11(4)
ObjectiveInterleukin-1 receptor antagonist (IL-1Ra) acts as an inhibitor of IL-1; which is one of the culprit cytokines in rheumatoid arthritis (RA). Although +2018 polymorphism of IL-1Ra has been implicated in the pathogenesis of RA, its importance remains poorly understood. Hence, the purpose of this study was to determine the clinical significance of interleukin-1 receptor antagonist (IL-1Ra) +2018 polymorphism in RA.MethodsPolymerase chain reaction (PCR) and sequencing were used to determine the genotypes of the IL-1Ra +2018 for 77 RA patients and 18 healthy controls. All RA patients were assessed for the disease activity score that includes 28 joints (DAS28) and radiographic disease damage based on Modified Sharp Score (MSS).ResultsThe frequency of the T/T and C/T genotypes did not differ significantly (p = 0.893) between the RA patients and the controls. The C/T genotype had significantly higher mean disease activity (DAS 28) and disease damage (MSS) scores with p values of 0.017 and 0.004, respectively. Additionally, the ESR (erythrocyte sedimentation rate), CRP (C-reactive protein), the number of swollen and tender joints were higher for the C/T individuals. On multivariate analysis the CRP, swollen joint count and MSS remained significant with the following p values i.e. 0.045, 0.046 and less than 0.05.ConclusionsC/T genotype of IL-1Ra +2018 prognosticates more aggressive disease in RA. 相似文献
22.
23.
Khir Nurul Ajilah Mohamed Noh Ain’ Sabreena Mohd Shafin Nazlahshaniza Ismail Che Aishah Nazariah 《Purinergic signalling》2021,17(2):201-213
Purinergic Signalling - Pain is the most common symptom reported by patients with rheumatoid arthritis (RA) even after the resolution of chronic joint inflammation. It is believed that... 相似文献
24.
Ismail Eş Maycon Carvalho Ribeiro Samuel Rodrigues dos Santos Júnior Amin Mousavi Khaneghah Armando Garcia Rodriguez André Corrêa Amaral 《Bioprocess and biosystems engineering》2016,39(10):1487-1500
The whole-cell immobilization on chitosan matrix was evaluated. Bacillus sp., as producer of CGTase, was grown in solid-state and batch cultivation using three types of starches (cassava, potato and cornstarch). Biomass growth and substrate consumption were assessed by flow cytometry and modified phenol–sulfuric acid assays, respectively. Qualitative analysis of CGTase production was determined by colorless area formation on solid culture containing phenolphthalein. Scanning electron microscopy (SEM) analysis demonstrated that bacterial cells were immobilized on chitosan matrix efficiently. Free cells reached very high numbers during batch culture while immobilized cells maintained initial inoculum concentration. The maximum enzyme activity achieved by free cells was 58.15 U ml?1 (36 h), 47.50 U ml?1 (36 h) and 68.36 U ml?1 (36 h) on cassava, potato and cornstarch, respectively. CGTase activities for immobilized cells were 82.15 U ml?1 (18 h) on cassava, 79.17 U ml?1 (12 h) on potato and 55.37 U ml?1 (in 6 h and max 77.75 U ml?1 in 36 h) on cornstarch. Application of immobilization technique increased CGTase activity significantly. The immobilized cells produced CGTase with higher activity in a shorter fermentation time comparing to free cells. 相似文献
25.
Miroslav Bobek Pittaya Tuntiwachwuttikul M. Mohsen Ismail Thomas J. Bardos 《Nucleosides, nucleotides & nucleic acids》2013,32(8):1657-1665
Abstract N-Aminopyrazine analogues of cytidine and 2′-deoxycytidine were prepared from 1-(β-D-ribofuranosyl)-1,2-dihydro-2-oxopyrazine and 1-(2-deoxy-β-D-ribofuranosyl)-1,2-dihydro-2-oxopyrazine, respectively, by amination with O-mesitylenesulfonylhydroxylamine. 相似文献
26.
The luncheon meat samples analyzed, which were produced locally by the two main luncheon meat producing companies in Egypt
were relatively highly contaminated either by moulds and yeasts in general, aflatoxigenic species and aflatoxin residues in
particular. The most frequently encountered fungi from the samples were yeasts, Aspergillus niger, A. flavus, Penicillium chrysogenum, Rhizopus stolonifer, Mucor circinelloides. Less common were Cladosporium sphaerospermum, Alternaria alternata, Mycosphaerella tassiana, P. aurantiogriseum and P. oxalicum. The most important aflatoxigenic species, A. flavus, was isolated frequently. It was 10% of the total fungal isolates from both samples of the two companies. Seven luncheon
meat samples out of 50 analyzed were positive for aflatoxin B1 or B1 and G1, while all samples were negative for aflatoxins B2, G2, M1 and M2. Aflatoxin B1 was detected only in 4 and 3 samples out of 25 analyzed from each of company A and B, respectively. The highest detectable
level, 11.1 ppb, was recorded in a sample from company B and the least, 0.5 ppb, in a sample from company A. Aflatoxin G1, at concentration of 3.2 ppb, was detected in only one sample of the aflatoxin B1 – contaminated 3 samples of company B: this sample also had the highest level of aflatoxin B1. Some luncheon meat samples had higher numbers of aflatoxigenic A. flavus than others, however these samples were negative for aflatoxins. The hazardous potential of such contamination will be discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
27.
Ismail AB Yoshinobu T Iwasaki H Sugihara H Yukimasa T Hirata I Iwata H 《Biosensors & bioelectronics》2003,18(12):1509-1514
This article reports an investigation on light-addressable potentiometric sensor (LAPS) to be used as a possible biological cell-semiconductor hybrid that will enable us to make an interface between the physical and biological system. To increase the surface potential sensitivity, we used a LAPS structure with single insulator (SiO2) coated with poly-L-ornithine and laminin (PLOL) on Si. Efficient culturing of PC-12 and nerve cells of Lymnaea stagnalis on PLOL-coated Si3N4 and SiO2 was achieved. The thickness of the PLOL layer was found to be about 4 nm by the atomic force microscope (AFM) measurement. Using the advantage of this thin layer of PLOL, we compared the performance of a novel structure to the previously reported "PLOL-coated Si3N4/SiO2/Si" structure. Due to high insulating capacitance, the photocurrent response of the novel LAPS was found to be very steep. As a result, higher sensitivity was achieved. This steepness did not degrade during 10 days when the sensor surface was kept in contact with the cell culture medium and environment. The thickness of PLOL layer, its ability to improve the biological cell adhesion, enhanced sensitivity, and experiment with simulated neural action potential (AP) applied to the novel LAPS show a good promise for LAPS to be a biological cell-semiconductor hybrid. 相似文献
28.
The genotoxic effects of fungicide Conan 5FL (containing 50 g/L hexaconazole) in mouse bone-marrow cells and human lymphocytes have been evaluated. Three different concentrations of Conan 5FL (17.50, 35.00 and 70.00 microg/mL for human lymphocytes and 17.50, 35.00 and 70.00 mg/kg for mouse bone marrow cells) were studied. Conan 5FL induced significant increases (except 17.50 mg/kg for mouse bone marrow) in the frequency of chromosomal aberrations (CAs) in both test systems. This fungicide caused structural and numerical abnormalities in both mammalian cells. These are sister chromatid union, chromatid and chromosome breaks, fragments, dicentric and ring chromosomes, and polyploidy. Significant increase was found in induction and in minimum-maximum numbers of sister chromatid exchanges (SCEs) at all treatments compared with the negative control. Conan 5FL did not affect the replication index (RI) in human lymphocyte cultures, however, it significantly decreased the mitotic index (MI) in all treatment concentrations in both test systems. Using of Conan 5FL should be reconsidered due to its possible cytotoxic, clastogenic and mutagenic effects. 相似文献
29.
Hassan Ammouneh Halah Ismail Alia Al-beda Nisreen Abou Baker Muhanad Harba 《Biocontrol Science and Technology》2013,23(6):607-623
Abstract As a part of an ongoing nationwide programme focused on finding novel strains of Bacillus thuringiensis (Bt) that are toxic to some of the major pests that impact economically important crops, we initiated a search for Bt isolates native to Syria. We succeeded in assembling a collection of 40 Bt isolates recovered from infected larvae of Galleria mellonella, Helicoverpa armigera and Ephestia kuehniella. Light microscopy showed that all isolates produce bipyramidal and cuboidal crystal proteins. The 50% lethal concentration of the spore-crystal mixture of the 40 isolates against E. kuehniella larvae varied from 3 to more than 200 µg g?1. A comparison of the LC50 values of the tested isolates with the reference strain Bt kurstaki HD-1 (20.55 µg g?1), showed that some of these isolates have a similar or up to six times higher toxicity potential. PCR screening revealed that all obtained isolates contain cry1 and cry2 genes, whereas only four contain cry9. Moreover, the proteins of 130 and 65/70 Kda encoded by these genes were detected in the SDS-PAGE of the purified parasporal bodies. Flagellar serotyping classified 30 as serovar kurstaki, six isolates serovar aizawai, one isolate cross-reacted with more than one H3 antisera and three were not typeable. Assays of toxicity of the aizawai isolates against third instar of G. mellonella showed that four, which contain cry9, have almost similar toxicity to the commercial strain Bt aizawai B401. Therefore, these isolates could be adopted for future applications to control G. mellonella. Moreover, this study contributes to our knowledge of Bt diversity in Syria where to date very few collections have been described. 相似文献
30.
Kinetic studies on cis-[Pt(NH3)2(OH2)2]2+ and various nucleobases show that this ion reacts more quickly with guanosine than with adenosine, cytidine, and thymidine, and that a monophosphoric acid unit considerably enhances the rate of reaction of guanosine; the kinetic preference of 5'-GMP over 5'-AMP may point to a greater thermodynamic selectivity. 相似文献