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   9505篇
  免费   701篇
  国内免费   281篇
耳鼻咽喉   92篇
儿科学   176篇
妇产科学   130篇
基础医学   835篇
口腔科学   554篇
临床医学   907篇
内科学   1505篇
皮肤病学   173篇
神经病学   1265篇
特种医学   699篇
外国民族医学   4篇
外科学   1065篇
综合类   1396篇
现状与发展   1篇
预防医学   333篇
眼科学   123篇
药学   426篇
  4篇
中国医学   215篇
肿瘤学   584篇
  2024年   19篇
  2023年   164篇
  2022年   289篇
  2021年   414篇
  2020年   361篇
  2019年   317篇
  2018年   291篇
  2017年   316篇
  2016年   308篇
  2015年   310篇
  2014年   558篇
  2013年   507篇
  2012年   469篇
  2011年   467篇
  2010年   413篇
  2009年   460篇
  2008年   485篇
  2007年   529篇
  2006年   450篇
  2005年   380篇
  2004年   304篇
  2003年   269篇
  2002年   276篇
  2001年   235篇
  2000年   183篇
  1999年   156篇
  1998年   133篇
  1997年   161篇
  1996年   132篇
  1995年   115篇
  1994年   117篇
  1993年   90篇
  1992年   93篇
  1991年   65篇
  1990年   65篇
  1989年   54篇
  1988年   55篇
  1987年   50篇
  1986年   65篇
  1985年   89篇
  1984年   50篇
  1983年   29篇
  1982年   36篇
  1981年   40篇
  1980年   31篇
  1979年   14篇
  1978年   14篇
  1976年   11篇
  1975年   14篇
  1973年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
We report a case of Noonan syndrome associated with central giant cell granuloma. The patient was a 101/2-year-old boy with the chief complaint of proptosis of the right eye. He also had various malformations such as short stature, webbed neck, pectus excavatum, cubitus valgus, pulmonary valve stenosis and patent foramen ovale, a characteristic face appearance and cryptorchidism and so on. Chromosome analysis showed a 46, XY karyotype. A computed tomographic scan and magnetic resonance imaging showed a mass originated from the lateral wall of the right maxillary sinus. The patient underwent Caldwell-Luc operation. Histological examination of the mass showed the characteristics of central giant cell granuloma. This case report describes a patient with the features of the recently described Noonan-like/multiple giant cell lesion syndrome.  相似文献   
52.
食管癌高低发区人群食管粘膜组织病理学研究   总被引:1,自引:0,他引:1  
目的探讨食管癌高、低发区人群食管粘膜上皮组织学改变,为癌前病变防治提供依据。方法高(林州市)、低发区(范县、清丰县)分别取无症状居民食管活检229人和187人,均分为4组,25岁~34岁、35岁~44岁、45岁~54岁及≥55岁,常规石蜡HE制片,按标准诊断归类。结果高、低发区食管上皮萎缩、棘层肥厚、炎细胞浸润相应年龄组比较无显著差异,基底细胞增生高发区35岁~44岁、45岁~54岁组显著大于低发区相应组(P=0.0312,P=0.0273),非典型增生45岁~54岁、≥55岁组高发区显著大于低发区相应组(P=0.0196,P=0.0263)。高、低发区总体人群比较除棘层肥厚、炎细胞浸润无差异外,余各病变间均有极显著差异(P<0.01)。结论食管上皮萎缩、基底细胞增生应作为较狭义的癌前病变对待,食管上皮棘层肥厚、炎细胞浸润似与食管癌变无关。  相似文献   
53.
Interruption of atrial flutter and fibrillation by RF catheter ablation may be favored by large, elongated lesions. We administered RF current in unipolar and bipolar mode in porcine right atrium. Bipolar ablation was performed between the tip electrodes of two serially coupled catheters. With 4-mm tip electrodes in vitro, lesion length increased from a mean (SD) of 7.9 (1.2) mm at 3 mm-interelectrode distance (IED) to 13.3 (3.3) mm at 9-mm IED, but decreased at 12-mm IED due to nonconfluent lesions (P < 0.0001), With 4 mm distal electrodes and 8 mm IED, bipolar lesions were 65% longer than corresponding unipolar ablations. Switching to bipolar mode increased the lesion length more than increasing electrode tip length to 6 mm in unipolar mode. Power and temperature controlled ablation created equally sized lesions. Twelve anesthetized pigs were randomized to unipolar or two catheter bipolar temperature controlled ablation of the right atrial free wall. Bipolar ablation created confluent lesions with endocardial length × width of 13.5 (5.8) × 7.3 (3.7) mm, unipolar ablation 6.4 (2.8) × 4.6 (1.4) mm (P < 0.001 when comparing length and P = 0.013 for lesion width). The atrial lesions in both groups were transmural and extended into hilar lung lesions with maximal depth of 3.0 (1.1) and 2.6 (1.0) mm, respectively (P = 0.44). Five bipolarly and four unipolarly ablated pigs developed right diaphragmal paresis. We conclude that bipolar ablation may be preferable in situations where large, elongated lesions are favorable. The two catheter technique is feasible in porcine right atrium. Both bipolar and unipolar ablation of the porcine right atrial free wall may frequently be complicated by injury to the phrenic nerve and adjacent lung tissue.  相似文献   
54.
目的通过对32例窒息后心肌受累的新生儿治疗前后心肌酶谱测定,了解心肌酶谱在窒息新生儿心肌损害诊治中的意义。方法32例均自入院后12h及治疗后5~7天各静脉采血1次,作GOT、LDH、CK、CK-MB检查。结果窒息后心肌损害治疗前后心肌酶谱各项指标比较差异均有显著统计学意义(P〈0.01),出院时心肌酶多恢复正常。结论对窒息新生儿做心肌酶谱检查,有利于早期发现心肌损害并及时治疗,并可作为判断疗效及预后的指标。  相似文献   
55.
During the early stages of nerve implantation, we followed the dynamic properties of the lateral gastrocnemius muscle of the rat, reinnervated with an acutely or chronically severed peroneal nerve. The aim of this study was to ascertain whether (1) the better functional recovery of a muscle reinnervated by a chronically severed foreign nerve is present from the onset of reinnervation, and (2) whether such functional improvement is due to the conditioning lesion effect. Our results indicate that better functional recovery is already apparent one week after nerve implantation, and it is due to the conditioning lesion effect, since tenotomy prevents such improvement. The tenotomy effect underlines the fact that some environmental factors concerning the target tissue, and not only the predegenerated nerve, are involved in the conditioning effect. © 1995 Wiley-Liss, Inc.  相似文献   
56.
Although the esophagus is the most frequent site ofCandida infections in the gastrointestinal tract, and many clinical studies about it have been reported, little attention has been directed toward experimental candidiasis of the esophagus, especially with regard to its ultrastructure. Using transmission electron microscopy, this study was performed to clarify the ultrastructure of experimental lesions, obtained from five New Zealand white male rabbits which were given a suspension ofCandida albicans cells (107/ml) for 13 days. The results showed that the lesions consisted of exfoliating, squamous epithelial cells with mycelial elements ofCandida albicans cells penetrating through them, and that a widened intercellular space between individual cells in the area of candidial invasion seems to be a characteristic finding of candidial infection. A part of this study was presented at the 25th Annual Meeting of the Clinical Electron Microscopy Society of Japan, Matsumoto, September 28–30, 1993.  相似文献   
57.
应用显微分光光度计测定15例鼻咽癌19处癌旁病变的上皮细胞核DNA含量并与浸润癌相比较。中、重度异型增生上皮细胞核DI及超过2.5c细胞的百分数处于单纯增生+轻度异型增生与浸润癌之间,3组DI及超过2.5c细胞的百分数差异显著。中、重度异型增生以非整倍体为主,其细胞核DNA含量组方图相似于浸润癌。从细胞核DNA含量角度来看,中、重度异型增生是重要的癌前病变。  相似文献   
58.
Expression of CDX2 and MUC2 in Barrett's mucosa   总被引:3,自引:0,他引:3  
Barrett's mucosa is a risk factor for esophageal adenocarcinoma and should be detected at an early stage. It is defined by the presence of columnar epithelium with goblet cells in the lower esophagus, but histologic diagnosis can be uncertain in the absence of distinct goblet cells. We investigated 55 biopsies from 48 patients with endoscopically plain Barrett's esophagus and performed immunohistochemistry for CDX2 and MUC2. In addition, alcian blue (pH 2,5)/PAS staining was done. In histologically unequivocal Barrett's mucosa, nuclear expression of CDX2 in goblet cells and many columnar cells, as well as cytoplasmic positivity for MUC2 in goblet cells, could be observed. Alcian blue (pH 2,5)/PAS stained acidic mucins in goblet cells and in some non-goblet columnar cells. In six cases, no definite Barrett's mucosa was present, and no expression of MUC2 could be observed. In these biopsies, there was granular cytoplasmic and/or focal nuclear staining for CDX2 in non-goblet columnar epithelial cells, indicating their intestinal differentiation. We suggest that this peculiar mucosa is the precursor of unequivocal Barrett's mucosa and would designate it early Barrett's mucosa. Alcian blue for acidic mucins is inconsistent in this epithelium and does not reliably indicate early intestinal differentiation.  相似文献   
59.
In intact cats, it is generally considered that the lateral posterior-pulvinar complex (LP-pulvinar) does not receive direct retinal terminals, with the exception of the retino-recipient zone known as the geniculate wing. There is, however, some evidence that early lesions of the visual cortex can occasionally induce the formation of novel retinal projections to the LP nucleus. Given the importance of knowing the connectivity pattern of the LP-pulvinar complex in intact and lesioned animals, we used the B fragment of cholera toxin, a sensitive anterograde tracer, to reinvestigate the retinal projections to the LP-pulvinar in normal cats and in cats with early unilateral lesions of the visual cortex (areas 17 and 18). Immunohistochemical localization of the toxin was performed to show the distribution and morphology of retinofugal terminals. A direct bilateral but predominantly contralateral retinal projection reached the caudal portion of LPl and LPm in the form of patches located mainly along its dorsomedial surface and many scattered terminals. The distribution of retinal projections to LP-pulvinar in intact and operated cats did not differ. Contrary to what had been previously reported, we found no evidence for lesion-induced sprouting of retinal axons in these higher-order thalamic nuclei. Retinal input to the LP-pulvinar might modulate visual responses driven by primary visual cortex or superior colliculus.  相似文献   
60.
von Hippel-Lindau (VHL) disease arises from mutations in the VHL gene and predisposes patients to develop a variety of tumors in different organs. In the kidney, single or multiple cysts and renal cell carcinomas (RCC) may occur. Both inter- and intrafamilial heterogeneity in clinical expression are well recognized. To identify VHL-dependent genetic factors, we investigated the renal phenotype in 274 individuals from 126 unrelated VHL families in whom 92 different VHL mutations were characterized. The incidence of renal involvement was increased in families with mutations leading to truncated protein (MLTP) or large rearrangement, as compared to families with missense changes (81 vs. 63%, respectively; P=0.03). In the latter group, we identified two mutation cluster regions (MCRs) associated with a high risk of harboring renal lesions: MCR-1 (codons 74-90) and MCR-2 (codons 130-136). In addition, the incidence of RCC was higher in families with MLTP than in families with missense changes (75 vs. 57%; P=0.04). Furthermore, mutations within MCR-1 but not MCR-2 conferred genetic susceptibility to develop RCC. Overall, our data argued for a substantial contribution of the genetic change in the VHL gene to susceptibility to renal phenotype in VHL patients.  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