全文获取类型
收费全文 | 5674篇 |
免费 | 430篇 |
国内免费 | 196篇 |
专业分类
耳鼻咽喉 | 178篇 |
儿科学 | 57篇 |
妇产科学 | 48篇 |
基础医学 | 992篇 |
口腔科学 | 206篇 |
临床医学 | 432篇 |
内科学 | 1131篇 |
皮肤病学 | 36篇 |
神经病学 | 483篇 |
特种医学 | 242篇 |
外国民族医学 | 5篇 |
外科学 | 837篇 |
综合类 | 683篇 |
现状与发展 | 1篇 |
预防医学 | 64篇 |
眼科学 | 75篇 |
药学 | 168篇 |
中国医学 | 29篇 |
肿瘤学 | 633篇 |
出版年
2024年 | 9篇 |
2023年 | 109篇 |
2022年 | 166篇 |
2021年 | 217篇 |
2020年 | 209篇 |
2019年 | 194篇 |
2018年 | 161篇 |
2017年 | 194篇 |
2016年 | 174篇 |
2015年 | 224篇 |
2014年 | 317篇 |
2013年 | 314篇 |
2012年 | 254篇 |
2011年 | 269篇 |
2010年 | 256篇 |
2009年 | 279篇 |
2008年 | 282篇 |
2007年 | 286篇 |
2006年 | 273篇 |
2005年 | 264篇 |
2004年 | 221篇 |
2003年 | 177篇 |
2002年 | 158篇 |
2001年 | 164篇 |
2000年 | 117篇 |
1999年 | 130篇 |
1998年 | 92篇 |
1997年 | 97篇 |
1996年 | 93篇 |
1995年 | 69篇 |
1994年 | 61篇 |
1993年 | 59篇 |
1992年 | 37篇 |
1991年 | 43篇 |
1990年 | 49篇 |
1989年 | 26篇 |
1988年 | 46篇 |
1987年 | 25篇 |
1986年 | 27篇 |
1985年 | 32篇 |
1984年 | 21篇 |
1983年 | 18篇 |
1982年 | 19篇 |
1981年 | 26篇 |
1980年 | 11篇 |
1979年 | 6篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1973年 | 3篇 |
排序方式: 共有6300条查询结果,搜索用时 15 毫秒
1.
Hiroshi Kashida 《Digestive endoscopy》2019,31(1):16-23
The aim of the present review was to clarify how we should detect and diagnose sessile serrated polyps (SSP) endoscopically. A systematic search was conducted of MEDLINE from January 2004 through March 2018. Nine findings: (i) proximal location; (ii) size >10 mm; (iii) irregular shape; (iv) indistinctive border; (v) cloud‐like surface; (vi) mucus cap; (vii) rim of debris in white‐light endoscopy; (viii) dilated vessels; and (ix) dilated crypts (pits) in image‐enhanced endoscopy were considered to be candidate discriminators of SSP from hyperplastic polyps. Prospective studies in a general setting are warranted to validate the above‐mentioned endoscopic features of SSP during real‐time colonoscopy and to determine whether these features are useful for the differential diagnosis of SSP. 相似文献
2.
3.
The serrated pathway (SP) can be viewed as two parallel, but partially overlapping, arrays of colorectal precursor lesions, and their respective endpoint carcinomas, that are distinct from those of the conventional adenoma–carcinoma sequence (APC‐pathway). In this review we focus at the outset on the clinical impact, pathological features, molecular genetics and biological behaviours of the various SP cancers. Then we summarize the clinicopathological features, classification and molecular profiles of the two main precursor lesions that anchor the respective pathways: (i) sessile serrated adenoma/polyp (SSA/P), also called sessile serrated lesion (SSL), and (ii) traditional serrated adenoma (TSA). Activating mutations of the RAS–RAF–MAPK pathway initiate and sustain the lesions of the SP, and CpG island methylation of the promoter regions of tumour suppressor and DNA repair genes play the major role in their neoplastic progression. The SP includes microsatellite stable (MSS) carcinomas that are among the most biologically aggressive colorectal carcinomas (CRC), and also accounts for the great preponderance of sporadic hypermutated, mismatch repair (MMR)‐deficient or microsatellite instable (MSI) CRC. The identification, removal and appropriate classification of at‐risk SP precursors and surveillance of individuals who harbour these lesions present a challenge and opportunity for CRC prevention and mortality reduction. 相似文献
4.
《Neurocirugía (Asturias, Spain)》2019,30(5):215-221
IntroductionTranssphenoidal surgical removal is the preferred treatment of most pituitary adenomas. Postoperative cerebrospinal fluid (CSF) leakage is the leading cause of morbidity after this procedure, with an incidence rate that varies from 0,5-15% in the main published series.ObjectivesThe primary objective of this study was to establish the incidence of postoperative CSF leakage in a sample of surgeries performed at the University Hospital of La Ribera by the same surgical team. The secondary objectives were to: ascertain the distinctive features between patients with and without postoperative CSF leakage, identify risk factors for their development, evaluate the relationship between the surgical technique for closing the sella turcica and the onset of postoperative CSF leakage and evaluate different treatment regimens for this complication.MethodsThe data of 302 consecutive transsphenoidal surgical procedures for pituitary adenoma removal which were performed between 1999 and 2017 were retrospectively reviewed.Results and conclusionsThe incidence of postoperative CSF leakage in our series was 2,3% (in accordance with similar published studies). It was possible to correlate intraoperative CSF leakage with two variables: pituitary macroadenoma and tumors with suprasellar extension (P < .005). This correlation did not exist for postoperative CSF leakage. We found a statistically significant correlation between intraoperative and postoperative CSF leakage (P < .005). Due to the low incidence of postoperative CSF leakage in our series, it was not possible to identify risk factors for its development. 相似文献
5.
Takashi Murakami Naoto Sakamoto Akihito Nagahara 《Journal of gastroenterology and hepatology》2019,34(10):1685-1695
Sessile serrated adenoma/polyps (SSA/Ps) are early precursor lesions in the serrated neoplasia pathway, which results in BRAF‐mutated colorectal carcinomas with not only high levels of microsatellite instability but also microsatellite stable. SSA/Ps with advanced histology, including cytological dysplasia or minimally invasive carcinomas, are important lesions because SSA/Ps are considered major contributors to “interval cancers” and these lesions can rapidly become dysplastic or invasive carcinomas. Clinicopathologically, SSA/Ps with dysplasia or invasive carcinoma were associated with advanced age, female sex, and proximal colon. Although SSA/Ps with submucosal invasive carcinoma were smaller and invaded less deeply into the submucosal layer than conventional tubular adenomas with submucosal invasive carcinoma, SSA/Ps with submucosal invasive carcinoma frequently had a mucinous component and exhibited a higher potential for lymphatic invasion and lymph node metastasis. In an SSA/P series, endoscopic characteristics, including (semi)pedunculated morphology, double elevation, central depression, and reddishness, may help accurately diagnose SSA/Ps with advanced histology. Removal of SSA/Ps with dysplasia or invasive carcinoma was recommended. Endoscopic treatment such as endoscopic mucosal resection or endoscopic submucosal dissection is useful for those lesions. However, surgical resection with lymph node dissection might be indicated when SSA/Ps with invasive carcinoma are endoscopically suspected, because these have the high risk of lymph node metastasis. Greater awareness may promote further research into improving the detection, recognition, and complete resection rates of SSA/Ps with dysplasia or invasive carcinoma and reduce the interval cancer rates. 相似文献
6.
目的探讨CT动态增强对鉴别肾上腺乏脂肪腺瘤与肾上腺结节样增生的价值。方法回顾性分析经手术病理证实的12例肾上腺乏脂肪腺瘤和27例肾上腺结节样增生患者的病例资料,统计两组病例各期增强CT值,利用公式灌注值P=CT静脉期-CT平扫期、廓清值C=CT静脉期-CT延迟期、绝对廓清灌注指数APC=(C/P)×100%及相对廓清灌注指数RAPC=(C/CT静脉期)×100%得到相关参数,并通过绘制受试者工作特征曲线,鉴别两者的最佳价值。结果肾上腺乏脂肪腺瘤直径较结节样增生更大;肾上腺乏脂肪腺瘤病灶各期CT值均明显高于结节样增生,且两者灌注值P、廓清值C、APC及RAPC有明显的统计学差异。年龄、性别、高血压、病灶位置、对侧肾上腺萎缩及动脉期CT值对鉴别两者无显著意义。结论CT动态增强扫描有助于鉴别肾上腺乏脂肪腺瘤和肾上腺结节样增生。 相似文献
7.
8.
神经导航辅助下经单鼻腔蝶窦入路切除垂体腺瘤 总被引:1,自引:1,他引:0
目的评价神经导航系统在经单鼻腔蝶窦人路垂体腺瘤切除手术中的应用。方法24例病人术前行MRI或CT连续薄层扫描,将影像学资料输入Brain LAB Vector Vision神经导航系统进行三维重建,标记出肿瘤及重要结构后,设计最佳手术入路,术中在导航的引导下定位蝶窦前壁、鞍底、海绵窦、颈内动脉和斜坡等结构,切除肿瘤。结果24例患者均在神经导航引导下经鼻蝶入路顺利到达肿瘤部位;注册误差0.3~2.0mm,平均(1.21±0.39)mm;肿瘤全切除19例,次全切除3例,大部分切除2例;术后19例病人症状有不同程度的改善,5例无变化,术后无严重并发症出现。结论神经导航辅助下经鼻蝶垂体腺瘤切除术具有定位准确、创伤小等优点.效果良好。 相似文献
9.
MR评价垂体腺瘤质地及与其胶原含量的关系 总被引:4,自引:1,他引:3
目的利用MR测量垂体腺瘤不同质地的信号强度,并分析其与肿瘤胶原含量间的关系。方法57例经手术证实的垂体腺瘤标本,术前均行MR检查,根据术中肿瘤硬度分为质地韧组(8例)与质地软组(49例),标本行天狼猩红染色检测其胶原含量。结果纤维化与非纤维化组T1WI瘤体/灰质信号强度比分别为1.31±0.31、1.16±0.26;T1WI瘤体/白质信号强度比分别为1.01±0.25、0.91±0.18,两组间差异无统计学意义(P(0.05);T1+WI瘤体/灰质信号强度比分别为1.83±0.28、1.84±0.51;T1+WI瘤体/白质信号强度比分别为1.56±0.24、1.46±0.37,两组间差异无统计学意义(P(0.05);T2WI瘤体/灰质信号强度比分别为1.15±0.26、1.57±0.46(P(0.05);T2WI瘤体/白质信号强度比分别为1.48±0.39、2.10±0.61,两组间有统计学意义(P(0.01);胶原含量分别为20.03%±7.99%、7.87%±4.82%,两组间有统计学意义(P<0.01);且T2WI瘤体/灰质、T2WI瘤体/白质与胶原含量呈显著负相关(r=-0.531、r=-0.726,P均(0.01)。结论术前MR可以预测垂体腺瘤的质地;其中以T2WI瘤体/白质为预测指标为最佳。胶原含量影响垂体腺瘤质地,MRI上T2WI可以反映其胶原含量的多少。 相似文献
10.
OBJECTIVE: Transanal endoscopic microsurgery (TEM) is a minimally invasive technique for excision of selected benign and malignant rectal neoplasms. It is considered a safe and effective treatment but recurrence rates of 1-13% are reported for benign lesions. The aim of this study was to assess risk factors for local recurrence of benign rectal lesions and to evaluate mortality and morbidity following TEM. METHOD: Data were prospectively collected from all patients undergoing TEM for benign adenomas from January 1998 to March 2005. The procedure was performed by a single surgeon and patients were regularly followed up. RESULTS: One hundred and forty-six procedures were included, with a median patient age of 74 years (range 22-92 years). The mean lesion area was 16 cm(2) (range 0.3-150 cm(2)) and the median distance from the dentate line was 9 cm (range 0-17 cm). Immediate complications included bleeding (six) and acute urinary retention (six). There has been one (0.68%) procedure-related death. After a median follow up of 39 months (range 4-89 months) there have been seven recurrences (4.8%), recurring at a mean time of 23.3 months (range 5-48 months). Only microscopic involvement of the circumferential resection margin was found to be significantly associated with recurrence (P = 0.0059). Recurrence was not associated with age, size of lesion, previous treatment, severity of dysplasia or use of the harmonic scalpel. CONCLUSION: TEM is a safe and effective treatment for benign rectal adenomas. Circumferential resection margin involvement is associated with recurrence, which tends to occur late. Therefore extended follow up is recommended. 相似文献