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   3554篇
  免费   245篇
  国内免费   12篇
耳鼻咽喉   45篇
儿科学   92篇
妇产科学   83篇
基础医学   500篇
口腔科学   133篇
临床医学   339篇
内科学   670篇
皮肤病学   92篇
神经病学   406篇
特种医学   72篇
外科学   387篇
综合类   20篇
预防医学   451篇
眼科学   73篇
药学   216篇
中国医学   22篇
肿瘤学   210篇
  2024年   11篇
  2023年   86篇
  2022年   140篇
  2021年   250篇
  2020年   152篇
  2019年   158篇
  2018年   200篇
  2017年   121篇
  2016年   135篇
  2015年   121篇
  2014年   161篇
  2013年   189篇
  2012年   287篇
  2011年   315篇
  2010年   172篇
  2009年   138篇
  2008年   183篇
  2007年   180篇
  2006年   167篇
  2005年   143篇
  2004年   134篇
  2003年   92篇
  2002年   80篇
  2001年   22篇
  2000年   24篇
  1999年   16篇
  1998年   13篇
  1997年   13篇
  1996年   12篇
  1995年   14篇
  1994年   5篇
  1993年   10篇
  1992年   3篇
  1991年   9篇
  1990年   10篇
  1989年   8篇
  1988年   5篇
  1987年   8篇
  1985年   3篇
  1984年   3篇
  1983年   2篇
  1982年   4篇
  1981年   3篇
  1980年   2篇
  1976年   1篇
  1975年   2篇
  1974年   1篇
  1973年   1篇
  1937年   1篇
  1928年   1篇
排序方式: 共有3811条查询结果,搜索用时 12 毫秒
91.
92.
93.
94.
95.
The case of a mentally retarded patient with congenital anomalies not typical of any known chromosome unbalance is reported. In his karyotype, 40·6% of the cells were normal, while 59·4% had a missing G and an almost metacentric marker longer than an F chromosome. The abnormal cell line was interpreted as resulting from a chromatid translocation involving the short arm of a No. 22 and a segment from an unidentified chromosome. The translocation probably took place after the first cell division and was followed by segregation of the translocated chromatids. Other obvious hypotheses were excluded by the study of fluorescence patterns. The patient's clinical features may be due to a partial autosomal trisomy.  相似文献   
96.
Transmissible spongiform encephalopathies are fatal neurodegenerative diseases attributed to misfolding of the cellular prion protein, PrP(C), into a β-sheet-rich, aggregated isoform, PrP(Sc). We previously found that expression of mouse PrP with the two amino acid substitutions S170N and N174T, which result in high structural order of the β2-α2 loop in the NMR structure at pH 4.5 and 20°C, caused transmissible de novo prion disease in transgenic mice. Here we report that expression of mouse PrP with the single-residue substitution D167S, which also results in a structurally well ordered β2-α2 loop at 20°C, elicits spontaneous PrP aggregation in vivo. Transgenic mice expressing PrP(D167S) developed a progressive encephalopathy characterized by abundant PrP plaque formation, spongiform change, and gliosis. These results add to the evidence that the β2-α2 loop has an important role in intermolecular interactions, including that it may be a key determinant of prion protein aggregation.  相似文献   
97.
Through chemical screening, we identified a pyrazolone that reversibly blocked the activation of phagocyte oxidase (phox) in human neutrophils in response to tumor necrosis factor (TNF) or formylated peptide. The pyrazolone spared activation of phox by phorbol ester or bacteria, bacterial killing, TNF-induced granule exocytosis and phox assembly, and endothelial transmigration. We traced the pyrazolone's mechanism of action to inhibition of TNF-induced intracellular Ca2+ elevations, and identified a nontransmembrane ("soluble") adenylyl cyclase (sAC) in neutrophils as a Ca2+-sensing source of cAMP. A sAC inhibitor mimicked the pyrazolone's effect on phox. Both compounds blocked TNF-induced activation of Rap1A, a phox-associated guanosine triphosphatase that is regulated by cAMP. Thus, TNF turns on phox through a Ca2+-triggered, sAC-dependent process that may involve activation of Rap1A. This pathway may offer opportunities to suppress oxidative damage during inflammation without blocking antimicrobial function.  相似文献   
98.
The effects of topical copaiba oil extract and topical corticosteroid were assessed on oral wound healing in an in vivo model using 96 male Wistar rats. Traumatic ulcers were caused in the dorsum of the tongue using a 3‐mm punch tool. The animals were divided into: Control; Corticosteroid; Placebo and Copaiba oil Group. The animals received two daily applications of the products. The control group received only daily handling. Six rats in each group were euthanized at days 3, 5, 10 and 14. The animals were monitored daily to determine wound status. The weigh was assessed at day 0 and euthanasia day. The percentage of repair was calculated, and histopathological aspects were analyzed. The Kruskal–Wallis test was used to compare the results between groups and times of evaluation. Closing time was assessed through the log‐rank test. The corticosteroid group lost more weight at days 10 and 14 than the control group (p < 0.05). Moreover, the healing time of corticosteroid group was longer than the control group (p = 0.007). No differences were observed between the copaiba oil group and the control group. We concluded that topical copaiba oil, in spite of being safe, did not accelerate the process of oral wound healing. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   
99.
Mucormycosis is an aggressive, rare and opportunistic infectious disease, with a high mortality rate. Etiologic agents are filamentous fungi, and infection among humans normally occurs through spore inhalation. A 61-year-old male individual, presenting left eye amaurosis, dark epistaxis, hyperalgesia and malodor underwent clinical examination, which detected ulcerative lesion and wide bone exposure in the hard palate and alveolar ridge. Direct microbiological examination, microbiological culture and lesion biopsy were performed. Non-septate smooth fungal hyphae forming right angles with each other were observed through the direct microbiological examination. Microbiological culture revealed fast-growing fungal colonies with cottony texture, identified as Rhizopus sp. Histopathological examination exhibited necrosis areas, intense mononuclear inflammatory infiltrate and bulky hyphae, thus concluding the mucormycosis diagnosis. Amphotericin B antifungal therapy and surgical intervention were adopted as treatment. The patient was then rehabilitated with maxillofacial prosthesis, subsequently to the healing of the surgical wound.  相似文献   
100.
Presence of the cfxA gene in Bacteroides distasonis   总被引:1,自引:0,他引:1  
In this study we investigated the presence of the cfxA gene (encoding a class A beta-lactamase) in 73 strains of the Bacteroides fragilis group belonging to the species B. distasonis (34), B. vulgatus (14), B. thetaiotaomicron (8), B. merdae (6), B. caccae (9) and B. ovatus (2) isolated from human intestinal microflora of healthy children and adults. Employing specific primers to the cfxA gene, a 312-bp amplified fragment was obtained in 2 strains of B. vulgatus and 9 strains, the majority from children, of B. distasonis. The expression of this enzyme was analysed by determining the MICs to cefoxitin and cefotaxime and values varied from 2 to >256 microg/ml of both cefoxitin and cefotaxime. Sequence analysis of the amplicons corresponding to the cfxA gene from B. distasonis and B. vulgatus revealed identical sequences between these isolates and high similarity with other beta-lactamase genes of anaerobes such as cfxA of B. vulgatus (99%) and cfxA2 of Prevotella intermedia (99%), both sequences of which deposited in Genbank under accession numbers U38243 and AF118110, respectively. However, a fragment obtained from a B. distasonis strain (EC17-4) showed a unique RFLP profile and 87% nucleotide similarity with cfxA and cfxA2 genes. These results seem to suggest a dissemination of these resistance determinants among Bacteroides species.  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