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   3651篇
  免费   129篇
  国内免费   44篇
耳鼻咽喉   5篇
儿科学   35篇
妇产科学   109篇
基础医学   865篇
口腔科学   47篇
临床医学   209篇
内科学   483篇
皮肤病学   32篇
神经病学   180篇
特种医学   131篇
外科学   188篇
综合类   114篇
预防医学   649篇
眼科学   18篇
药学   567篇
中国医学   83篇
肿瘤学   109篇
  2024年   3篇
  2023年   104篇
  2022年   138篇
  2021年   133篇
  2020年   189篇
  2019年   152篇
  2018年   130篇
  2017年   270篇
  2016年   257篇
  2015年   273篇
  2014年   332篇
  2013年   253篇
  2012年   165篇
  2011年   142篇
  2010年   177篇
  2009年   181篇
  2008年   72篇
  2007年   114篇
  2006年   94篇
  2005年   41篇
  2004年   40篇
  2003年   30篇
  2002年   38篇
  2001年   35篇
  2000年   30篇
  1999年   57篇
  1998年   58篇
  1997年   53篇
  1996年   67篇
  1995年   53篇
  1994年   47篇
  1993年   30篇
  1992年   14篇
  1991年   14篇
  1990年   13篇
  1989年   16篇
  1988年   4篇
  1984年   1篇
  1982年   1篇
  1980年   1篇
  1977年   1篇
  1969年   1篇
排序方式: 共有3824条查询结果,搜索用时 406 毫秒
71.
《Ticks and Tick》2022,13(5):102005
A Coxiella-like endosymbiont (Coxiella-LE hereinafter) stably infects and influences Haemaphysalis longicornis development, indicating a mutualistic relationship of Coxiella-LE and ticks. To further elucidate the patterns of growth dynamics and tissue localization of Coxiella-LE in H. longicornis, 16S rRNA high-throughput sequencing, quantitative PCR (qPCR), and fluorescence in situ hybridization (FISH) were used in this study. The density of Coxiella-LE varied among different tick life stages, and fed female ticks had the highest density, followed by unfed female and unfed larval ticks. In the four organs that were dissected from fed female ticks, the ovary carried the highest density of Coxiella-LE, which was significantly different from salivary glands, midgut and Malpighian tubules. The high abundance of Coxiella-LE in fed female ticks and in the ovaries of fed female ticks in the bacterial microbiota analyses further confirmed that Coxiella-LE rapidly proliferates in the ovary after blood feeding. The ovaries continued to develop after engorgement and oviposition began on day 5, with a significant decrease in the density of Coxiella-LE in the ovaries occurring on day 7. FISH results indicated that Coxiella-LE is mainly colonized in the cytoplasm of the oocyte and proliferates with oogenesis. Coxiella-LE was expelled from the body with the mature oocyte, ensuring its vertical transmission. In the Malpighian tubules at different days after engorgement, the white flocculent materials were increasing, and the density of Coxiella-LE raised significantly on day 7. Unlike the localization pattern in the ovary, Coxiella-LE was initially distributed in a mass and continually increased during the development of Malpighian tubules until it filled the Malpighian tubules. These findings provide new insights on the growth dynamics and tissue localization of Coxiella-LE in ticks and are useful for further investigation on the interactions of symbiont and ticks .  相似文献   
72.
Mammary epithelial cells (MECs) play an important role against Streptococcus uberis infection which is one of the main causes of bovine mastitis and a potential threat to human health. Toll-like receptors (TLRs) and their mediated signaling pathways are critical in both innate and infection responses, yet their roles in anti-S. uberis infection in MECs remains poorly defined. In this work we investigated the regulatory mechanisms of TLR2 in inflammatory responses, where WT and TLR2−/− mice were euthanized at 15–18 days gestation, and mammary gland tissues were collected aseptically. The mouse MECs (MMECs) were isolated by combined digestion with type I collagenase, hyaluronidase and trypsin. We challenged MMECs with S. uberis and quantified antioxidant capacity as well as reactive oxygen species (ROS), proinflammatory cytokines and cell damage at different times. The loss of TLR2 function in MMECs results in more serious cell damage, increased cell adhesion, and significantly decreased ROS and mitochondrial ROS (mROS) with bactericidal function in response to S. uberis infection. Moreover, it was observed that the antioxidant capacity declined, and the production of TLR2-mediated cytokines (except CXC ligand 15) also were reduced. We demonstrated that TLR2 can mediate cellular anti-infective processes in MMECs by regulating the production of ROS and mROS and the secretion of cytokines. The results suggest an unpredicted role of TLR2 in MMECs in response to S. uberis infection.  相似文献   
73.
74.
Wild-growing mushrooms could be a potential source of mineral elements The aim of this study was to analyze the mineral composition of 18 species of wild-growing mushrooms collected in a natural park from the Spanish southeast (province of Granada). Ca, Mg, K, Na, Fe, Cu and Zn, were determined by flame atomic absorption spectroscopy and P was analyzed colorimetrically by the vanadomolybdate procedure; the accuracy of methods was assessed by the use of certified reference materials. The contribution of mushrooms consumption to the mineral daily recommended intakes was calculated. Although large variations were observed between species, the most abundant mineral elements in the analyzed mushrooms were K and P, with average contents of 29.3 ± 8.1 and 8.60 ± 4.8 g/kg dry matter (dm), respectively. Low Na concentrations were observed (26.5–579 mg/kg dm), with the only exception of Amanita ovoidea, and high Fe values, exceeding in some cases 1000 mg/kg dm (such as in Lactarius deliciosus and Morchella conica). Mushrooms may be significant contributors of K and P in the human diet and also good sources of trace elements, especially Cu and Fe, providing negligible quantities of Na. Strong correlations were observed for Ca/Mg and Cu/Zn contents in the mushrooms analyzed.  相似文献   
75.
76.
Natural environments may be important for subjective wellbeing, yet evidence is sparse and measures of nature are unspecific. We used linear regression models to investigate the relationship between greenness, biodiversity and blue space and subjective wellbeing in 4,912 adults living in metropolitan Melbourne, Australia. Greenness (overall, private and public) and biodiversity associated with subjective wellbeing. In particular, we highlight the importance of the private greenness-subjective wellbeing association. Our work has implications for urban policy and planning in the context of increased urban densification.  相似文献   
77.
The role of oxytocin (OT) as a neuropeptide that modulates social behavior has been extensively studied and reviewed, but beyond these functions, OT’s adaptive functions at birth are quite numerous, as OT coordinates many physiological processes in the mother and fetus to ensure a successful delivery. In this review we explore in detail the potential adaptive roles of oxytocin as an anti-inflammatory, protective molecule at birth for the developing fetal brain and gastrointestinal system based on evidence that birth is a potent inflammatory/immune event. We discuss data with relevance for a number of neurodevelopmental disorders, as well as the emerging role of the gut-brain axis for health and disease. Finally, we discuss the potential relevance of sex differences in OT signaling present at birth in the increased male vulnerability to neurodevelopmental disabilities.  相似文献   
78.
79.
80.
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