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   3256篇
  免费   191篇
  国内免费   173篇
耳鼻咽喉   45篇
儿科学   24篇
妇产科学   1篇
基础医学   232篇
口腔科学   2篇
临床医学   299篇
内科学   1327篇
皮肤病学   7篇
神经病学   108篇
特种医学   66篇
外国民族医学   3篇
外科学   318篇
综合类   554篇
预防医学   69篇
眼科学   1篇
药学   104篇
  1篇
中国医学   41篇
肿瘤学   418篇
  2024年   5篇
  2023年   32篇
  2022年   51篇
  2021年   82篇
  2020年   69篇
  2019年   83篇
  2018年   92篇
  2017年   79篇
  2016年   92篇
  2015年   108篇
  2014年   174篇
  2013年   194篇
  2012年   138篇
  2011年   190篇
  2010年   136篇
  2009年   186篇
  2008年   182篇
  2007年   186篇
  2006年   199篇
  2005年   184篇
  2004年   135篇
  2003年   116篇
  2002年   95篇
  2001年   90篇
  2000年   81篇
  1999年   67篇
  1998年   57篇
  1997年   50篇
  1996年   60篇
  1995年   59篇
  1994年   71篇
  1993年   35篇
  1992年   36篇
  1991年   37篇
  1990年   33篇
  1989年   18篇
  1988年   18篇
  1987年   19篇
  1986年   21篇
  1985年   10篇
  1984年   10篇
  1983年   7篇
  1982年   7篇
  1981年   7篇
  1980年   4篇
  1979年   5篇
  1978年   3篇
  1977年   3篇
  1976年   2篇
  1970年   1篇
排序方式: 共有3620条查询结果,搜索用时 20 毫秒
31.
Summary In a series of 79 cases of primary esophageal carcinoma resected at The Center for Adult Diseases, Osaka, there were six tumors with specific histopathologic features valid for the diagnosis of argyrophil cell carcinoma. Of the 6 tumors, 3 were studied electron microscopically and assay for ACTH content was performed on 4 tumors.Clinically, the ages of the 6 patients ranged from 56 to 71 years; two were women and four men. Four of the 6 patients died with widespread tumor recurrences within 9 months of operation.Microscopically, the 6 tumors were composed largely or almost entirely of small, spindle-shaped cells resembling those of oat cell carcinoma of the lung, and were characterized by the arrangement of tumor cells in solid sheets or anastomosing cords, the presence of argyrophil tumor cells, and the deposits of amyloid. Electron microscopically, the three tumors contained neurosecretory-type granules. Using bioassay or radioimmunoassay ACTH activity in the tumor tissues was detected in 3 out of the 4 tumors determined.From the light and electron microscopic characteristics and the assay evidence, it seems reasonable to conclude that the 6 tumors are endocrine polypeptide producing tumors (apudomas) that arise from argyrophil cells normally found among the basal cells of the esophageal mucosa, and that they represent a distinct histopathologic entity clearly distinguishable from other types of esophageal carcinomas.Supported in part by a Grant-in Aid for Cancer Research from the Ministry of Education, Science and Culture, and the Ministry of Health and Welfare, JapanThe authors are grateful to Prof. H. Imura and Dr. Y. Hirate, Department of Internal Medicine, Kobe University School of Medicine for their interest and performing the assays for ACTH on the tumor tissues.  相似文献   
32.
胎儿消化器官发育中的肥大细胞超微结构特点   总被引:3,自引:0,他引:3  
实验对10例不同胎龄肥儿消化器官的胎大细胞进行了超微结构观察,发现胎儿发育接近成熟时,其肥大细胞根据颗粒的超微结构可分TC肥大细胞和T肥大细胞两型;胎儿发育后期以大细胞有分泌活动呈活化状态;胎儿肥大细胞与成纤维细胞,上皮细胞,血管,神经等密切接触。  相似文献   
33.
Adenocarcinoma of the esophagus, or GEJ, has a poor prognosis. Early lesions [i.e. high grade dysplasia (HGD) or T1-carcinoma] are potentially curable. Local endoscopic therapies are promising treatment options for superficial lesions; however, for deeper lesions, surgical resection is considered to be the treatment of choice. To contribute to therapeutic decision-making, we retrospectively analysed the outcome of transhiatal esophagectomy in 120 patients with pathologically proven HGD (n=13) or T1-adenocarcinoma (n=107) of the distal esophagus or gastro-esophageal junction (GEJ). Tumors were subdivided into six different depths of invasion (T1-mucosal m1-m3, T1-submucosal sm1-sm3), and the frequency of lymphatic dissemination and time to locoregional and/or distant recurrence were analysed. Only one of the 79 T1m1-3/sm1 tumors (1%) showed lymph node metastases as compared with 18 out of 41 T1sm2-3 tumors (44%). There was a significant difference in recurrence-free period between T1m1-m3/sm1 versus T1sm2-sm3 tumor patients (P log rank <0.0001), with 5-year recurrence-free percentages of 97% and 57%, respectively. In multivariate analysis including age, gender, tumor differentiation grade, N-stage and depth of invasion, only N-stage was an independent prognostic factor for recurrence-free period (hazard rate=5.9, 95% CI 1.7–20.7). However, if N-stage was excluded from analysis, only depth of invasion (T1sm2-3 versus T1m1-m3/sm1) was an independent prognostic factor for recurrence-free period (hazard rate=7.5, 95% CI 2.0–27.7). These data indicate that T1m1-m3/sm1 adenocarcinomas of esophagus or GEJ show a very low risk of lymphatic dissemination and are therefore eligible for local endoscopic therapy. After transhiatal surgical resection, almost half of the patients with T1sm2-sm3 lesions develop recurrent disease within 5 years, and therefore need additional therapy to improve survival.  相似文献   
34.
大鼠消化道神经激肽A的发育研究   总被引:3,自引:1,他引:3  
应用免疫细胞化学PAP法系统研究了大鼠胚胎13天至成年食道及胃神经激肽A发生发育过程。结果如下:(1)在食道,直至出生前,即胚胎21天才于环肌层及粘膜肌层出现阳性膨体纤维,出生后,随幼鼠的生长发育相继在上皮内、纵肌层、肌间丛、粘膜下丛出现神经激肽A免疫反应阳性物,其纤维的密度、粗细和着色也逐渐增加,30天时已具备成年的分布特征,其发育主要在生后4周;(2)在胃,于胚胎14天,首先在肌间丛处呈现阳性  相似文献   
35.
The pepsinogen A (PGA) isozymogens in the gastric mucosa and Barrett epithelium of a female patient with Barrett esophagus were studied on different occasions during a 3-year period by electrophoretic analysis of in vivo steady-state pepsinogen in biopsies by activity staining in combination with variant specific monoclonal antibodies and of de novo synthesized pepsinogen by autoradiography. In Barrett epithelium only one (Pg3) or two (Pg3 and Pg5) primary PGA gene products were detected, whereas in gastric mucosal biopsies three (Pg3, Pg4 and Pg5) primary gene products were demonstrated on all occasions. These differences strongly suggest differential expression/activation of individual gene numbers in the PGA gene cluster in Barrett esophagus and are in line with the preneoplastic nature of this condition. The mechanism behind this deregulation is currently under investigation by cell biology and molecular genetic techniques.  相似文献   
36.
李质馨  王彦 《解剖学杂志》1994,17(5):401-404
用引产后死亡的正常胎儿(32 ̄40周,15个)食管,将其分颈部,胸部上、中、下,腹部食管5部分。对各部位食管肌间神经丛内胆碱能神经元,进行光镜(chAT、AChE)和电镜(AchE)酶组织化学定位、定量观察。结果表明,胆碱能神经元的分布及细胞内酶含量,在食管各部位不同,AChE在电镜下定位于粗面内质网。这一研究结果,不仅将使食管胆碱能神经支配及其生理功能等基础理论知识,得到进一步阐明、丰富和发展;  相似文献   
37.
本文测量了58具成年尸体食管胸段的长度,用内外相关和自身比例的方法,着重对食管胸段前邻器官的占位及其在胸骨上的投影作了定位研究,并结合临床应用进行了讨论。  相似文献   
38.
目的 探讨P53 及c -myc蛋白在食管癌及癌前病变中的表达及意义。方法 应用免疫组化SP法检测P53 及c -myc在 6 0例食管癌及 33例非典型增生中的表达。 结果 P53 及c -myc蛋白分别在食管癌与非典型增生I~II级中表达有显著差异 (P <0 .0 5 ) ;在食管癌与非典型增生III级表达中无显著差异 (P >0 .0 5 )。结论 P53 及c -myc蛋白异常表达 ,可为食管癌和癌前病变界限的划分提供参考依据。  相似文献   
39.
目的探讨早期食管癌的组织发生学.方法对109例早期食管癌及癌周病变进行病理观察.结果其中20例的一点癌(黄豆大小),3例双原发癌,1例小细胞癌.癌周伴有不同程度的鳞状上皮异形增生和不典型增生.结论早期食管具有多样性生长的特点.提示临床医生在胃镜检查应注意多点取材,以防漏诊;以及正确确定手术范围,防止手术残留.  相似文献   
40.
BackgroundSleeve gastrectomy (SG) leads to esophageal mucosal damage in an elevated percentage of cases, configuring a clinical condition of Barrett’s esophagus (BE) in a proportion as high as 15–18.8%. BE may rarely evolve into esophageal adenocarcinoma (EAC).ObjectivesTo raise awareness of BE as a precancerous lesion which may progress toward malignancy after this popular bariatric procedure.SettingBariatric referral centers, Italy.MethodsAll patients referred to our bariatric center who developed an EAC after SG between 2012 and 2019 were reviewed and consecutively included in this study. The available scientific literature regarding this complication is additionally reviewed.ResultsThe 3 male patients comprised in this case series underwent laparoscopic SG between 2012 and 2015 in different bariatric referral centers. Age and body mass index at baseline ranged from 21–54 years and 43.1–75.6 kg/m2, respectively. All patients were lost to follow-up early after surgery (3.7 ± 1.4 months), and were diagnosed with EAC at a mean of 27.3 ± 7.6 months after SG. The 4 reported cases in the scientific literature developed an EAC at a mean of 32.5 ± 23 months from SG. Overall, a diagnosis of EAC was made approximately 30.3 ± 17.1 months postoperatively, which seems relatively and worryingly early after surgery.ConclusionAlthough the rate and probability of progression from BE to EAC is still not well defined, assuming that the rising popularity and execution of SG leads to a growth in the BE incidence, then the preoperative identification and stratification of cancer risk factors in this subset of patients is strongly encouraged. Clinical and endoscopic follow-ups are essential to allow for prevention and early diagnosis and for epidemiologic data collection purposes.  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