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   7565篇
  免费   457篇
  国内免费   20篇
  2023年   95篇
  2022年   237篇
  2021年   385篇
  2020年   343篇
  2019年   486篇
  2018年   393篇
  2017年   272篇
  2016年   356篇
  2015年   399篇
  2014年   492篇
  2013年   642篇
  2012年   595篇
  2011年   588篇
  2010年   318篇
  2009年   276篇
  2008年   292篇
  2007年   318篇
  2006年   264篇
  2005年   229篇
  2004年   189篇
  2003年   134篇
  2002年   124篇
  2001年   41篇
  2000年   47篇
  1999年   42篇
  1998年   22篇
  1997年   27篇
  1996年   18篇
  1995年   16篇
  1994年   14篇
  1993年   19篇
  1992年   28篇
  1991年   21篇
  1990年   17篇
  1989年   27篇
  1988年   12篇
  1987年   24篇
  1986年   19篇
  1985年   22篇
  1984年   18篇
  1983年   15篇
  1982年   12篇
  1981年   11篇
  1980年   13篇
  1979年   19篇
  1975年   12篇
  1974年   10篇
  1973年   11篇
  1971年   13篇
  1970年   9篇
排序方式: 共有8042条查询结果,搜索用时 15 毫秒
91.
International Journal of Peptide Research and Therapeutics - Acinetobacter baumannii is an important pathogen responsible for nosocomial infections worldwide. Trimeric autotransporters, the...  相似文献   
92.
The relationship between the severity of dengue infection and allergy is still obscure. We conducted an electronic search across 12 databases for relevant articles reporting allergic symptoms, dengue infection, and dengue classification. These studies were categorized according to dengue severity and allergy symptoms, and a meta-analysis was performed by pooling the studies in each category. Among the included 57 articles, pruritus was the most common allergic sign followed by non-specified allergy and asthma(28.6%, 13%, and 6.5%, respectively). Despite the reported significant association of dengue with pruritus and total Ig E level(P \ 0.05), in comparison with non-dengue cases and healthy controls, there was no association between the different severe dengue group with pruritus, skin allergy, food allergy or asthma. However,removing the largest study revealed a significant association between asthma with dengue hemorrhagic fever(DHF) rather than dengue fever(DF). In comparison with DF, DHF was associated with Ig E positivity. Furthermore, specific-Ig E level was higher in secondary DF rather than primary DF. There was a possible association between allergy symptoms and dengue severity progression. Further studies are needed to clarify this association.  相似文献   
93.
Consumers’ demand is increasing for safe foods without impairing the phytochemical and sensory quality. In turn, it has increased research interest in the exploration of innovative food processing technologies. Cold plasma technology is getting popularity now days owing to its high efficacy in decontamination of microbes in fruit and fruit-based products. As a on-thermal approach, plasma processing maintains the quality of fruits and minimizes the thermal effects on nutritional properties. Cold plasma is also exploited for inactivating enzymes and degrading pesticides as both are directly related with quality loss and presently are most important concerns in fresh produce industry. The present review covers the influence of cold plasma technology on reducing microbial risks and enhancing the quality attributes in fruits.  相似文献   
94.
95.
96.
97.
Failed oocyte activation has been observed in unexplained infertile (UI) and asthenoteratozoospermic (AT) men. The deficiency of phospholipase C‐zeta (PLCζ) could be a possible reason for such failures and has not been studied yet. We investigated the expression and localization of PLCζ protein in the sperms of patients with UI and AT conditions. The relationships between PLCζ‐related parameters with male age, sperm characteristics, DNA integrity, and cellular maturity were assessed. Semen samples were collected from fertile (n = 40), UI (n = 40), and AT (n = 40) men. Subsequently, semen analysis, DNA fragmentation, hyaluronic acid‐binding ability, and PLCζ level along with its distribution were evaluated using computer‐assisted sperm analyzer, sperm chromatin structure assay (SCSA), hyaluronic acid‐binding assay (HBA), western blot analysis and immunofluorescence microscopy, respectively. Unlike SCSA, the values of HBA, and PLCζ expression were significantly reduced in UI and AT patients compared to fertile men, whereas no significant differences were observed among the experimental groups in terms of PLCζ localization patterns. The regression analysis also showed that HBA is the only variable associated with PLCζ levels. Furthermore, the correlation of male age with PLCζ localization in postacrosomal, equatorial, and acrosomal+postacrosomal+equatorial (A+PA+E) patterns, as well as the relation of normal morphology, with the (A+PA+E) pattern, remained in the regression model. Our findings indicated that reduced PLCζ level along with the increased DNA fragmentation and impaired maturation may be possible etiologies of decreased fertilization in the studied subjects.  相似文献   
98.
Russian Journal of Bioorganic Chemistry - Pyridazines hold considerable interest relative to pharmacologically active molecules. The pyridazine compounds are exhibited different types of...  相似文献   
99.
In the present work, a novel biocompatible scaffold was fabricated for the DNA aptamer immobilization. For the first time, amino‐functionalized dendritic fibrous nanosilica (KCC‐1‐nPr‐NH2) and gold nanoparticle supported by chitosan (AuNPs‐CS) were synthesized and electrodeposited successfully on the surface of the glassy carbon electrode by chronoamperometry technique. Unique oligonucleotide of aflatoxin M1 (5′‐ATC CGT CAC ACC TGC TCT GAC GCT GGG GTC GAC CCG GAG AAA TGC ATT CCC CTG TGG TGT TGG CTC CCG TAT) labeled by toluidine blue was immobilization on the prepared interface. Hence, a novel aptamer‐based bioassay was formed for highly sensitive quantitation of AFM1 using cyclic voltammetry and differential plus voltammetry. The structure and morphology of GQDs‐CS/KCC‐1‐nPr‐NH2 were investigated by Fourier‐transform infrared spectroscopy, X‐ray diffraction, atomic force, scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy. The achieved low limit of quantification of apta‐assay for detection of AFM1 was 10fM. Also, calibration curve was linear from 0.1μM to 10fM in real samples. The proposed apta‐assay has acceptable long‐term stability. Designed aptasensor has a lot of remarkable advantages including excellent selectivity, sensitivity, and stability that could be used as facile bio‐device for the determination of AFM1 in milk samples.  相似文献   
100.
In this study, a novel electroconductive interface was prepared based on Fe3O4 magnetic nanoparticle and cysteamine functionalized gold nanoparticle. The engineered interface was used as signal amplification substrate in the electrochemical analysis of antibody‐antigen binding. For this purpose, biotinilated‐anti‐prostate‐specific antigen (PSA) antibody was bioconjugated with iron oxide magnetic nanoparticles (Fe3O4) and drop‐casted on the surface of glassy carbon electrode (GCE). Also, secondary antibody (HRP‐Ab2) encapsulated on gold nanoparticles caped by cysteamine was immobilized on the surface of GCE modified electrode. A transmission electron microscopy images shows that a sandwich immunoreaction was done and binding of Ab1 and Ab2 performed successfully. Various parameters of immunoassay, including the loading of magnetic nanoparticles, the amount of gold nanoparticle conjugate, and the immunoreaction time, were optimized. The detection limit of 0.001 μg. L?1 of PSA was obtained under optimum experimental conditions. It is found that such magneto‐bioassay could be readily used for simultaneous parallel detection of multiple proteins by using multiple inorganic metal nanoparticle tracers and are expected to open new opportunities for early stage diagnosis of cancer in near future.  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