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   7358篇
  免费   303篇
  国内免费   30篇
耳鼻咽喉   60篇
儿科学   186篇
妇产科学   101篇
基础医学   823篇
口腔科学   113篇
临床医学   360篇
内科学   1692篇
皮肤病学   74篇
神经病学   788篇
特种医学   190篇
外科学   1239篇
综合类   26篇
预防医学   204篇
眼科学   262篇
药学   605篇
中国医学   19篇
肿瘤学   949篇
  2023年   47篇
  2022年   78篇
  2021年   120篇
  2020年   75篇
  2019年   116篇
  2018年   135篇
  2017年   99篇
  2016年   140篇
  2015年   126篇
  2014年   166篇
  2013年   213篇
  2012年   323篇
  2011年   370篇
  2010年   223篇
  2009年   181篇
  2008年   376篇
  2007年   365篇
  2006年   442篇
  2005年   464篇
  2004年   495篇
  2003年   492篇
  2002年   469篇
  2001年   157篇
  2000年   148篇
  1999年   157篇
  1998年   137篇
  1997年   102篇
  1996年   95篇
  1995年   75篇
  1994年   68篇
  1993年   82篇
  1992年   121篇
  1991年   111篇
  1990年   113篇
  1989年   85篇
  1988年   75篇
  1987年   73篇
  1986年   60篇
  1985年   41篇
  1984年   46篇
  1983年   51篇
  1982年   35篇
  1981年   25篇
  1980年   29篇
  1979年   30篇
  1978年   20篇
  1977年   28篇
  1976年   26篇
  1972年   21篇
  1971年   19篇
排序方式: 共有7691条查询结果,搜索用时 15 毫秒
81.
Three THAs with cementless monolithic alumina ceramic sockets and cementless Co-alloy stems were retrieved because of aseptic loosening after 17 and 24 years. At revision heads and cups were marked for orientation. Maps were drawn of wear patterns with the use of light microscopy and surveyed by SEM. In a simulator experiment 28-mm-diameter alumina heads and liners were used. The cups were mounted inverted in a hip simulator and run with calf serum as the lubricant. The hip loads were 2 kN maximum and a 1-Hz frequency for 20 million cycles. Wear severity was classified into five grades. In retrieved implants, SEM analysis showed that the main wear zones (MWZ) had Grade 4 wear. The peripheral wear zones (PWZ) showed grain pull-out regions (Grade 5 wear). These corresponded to neck-socket impingement and head-acetabular cup separation. Gray was due to transferred CoCr particles from the stem. In the simulator study, the MWZ had only localized areas of grain pull out surrounded by polished surface regions (Grade 4 wear) at 20 million cycles; stripe wear was not seen. The alumina ceramic bearings proved excellent up to 22 years in simulator studies and clinical studies. However, microseparation kinematics would be necessary in the simulator to duplicate the more peripheral wear zones.  相似文献   
82.
Iodoacetamide (IAA), an ulcerogenic compound, was continuously given to male Wistar rats for up to 74 weeks. No carcinomas developed but marked glandular hyperplasias were frequently observed accompanied by chronic ulcer or erosion in the fundic region. They showed pseudo-invasive growth into the submucosa, the granulomatous tissue and even into the muscle layer, but no cellular and nuclear atypia was observed in their glands. Characteristically the mucosal damage caused by chronic IAA treatment was restricted to the fundic mucosa along the limiting ridge. Abnormally regenerated mucosa in the damaged area showed pyloric gland type metaplasia, demonstrated histo-chemically by paradoxical concanavalin A-staining and high-iron diamine-Alcian blue staining for mucin. No intestinal metaplasia was observed in these mucosa.  相似文献   
83.
BackgroundExtrahepatic recurrence and early intrahepatic recurrence of hepatocellular carcinoma after hepatic resection are indicative of poor prognoses. We aimed to develop nomograms to predict extrahepatic recurrence and early intrahepatic recurrence after hepatic resection.MethodsThe participants of this study were 1,206 patients who underwent initial and curative hepatic resection for hepatocellular carcinoma. Multivariate logistic regression analyses using the Akaike information criterion were used to construct nomograms to predict extrahepatic recurrence and early intrahepatic recurrence (within 1 year of surgery) at the first recurrence sites after hepatic resection. Performance of each nomogram was evaluated by calibration plots with bootstrapping.ResultsExtrahepatic recurrence was identified in 95 patients (7.9%) and early intrahepatic recurrence in 296 patients (24.5%). Three predictive factors, α-fetoprotein >200 ng/mL, tumor size (3–5 cm or >5 cm vs ≤3 cm), and image-diagnosed venous invasion by computed tomography, were adopted in the final model of the extrahepatic recurrence nomogram with a concordance index of 0.75. Tumor size and 2 additional predictors (ie, multiple tumors and image-diagnosed portal invasion) were adopted in the final model of the early intrahepatic recurrence nomogram with a concordance index of 0.67. The calibration plots showed good agreement between the nomogram predictions of extrahepatic recurrence and early intrahepatic recurrence and the actual observations of extrahepatic recurrence and early intrahepatic recurrence, respectively.ConclusionWe have developed reliable nomograms to predict extrahepatic recurrence and early intrahepatic recurrence of hepatocellular carcinoma after hepatic resection. These are useful for the diagnostic prediction of extrahepatic recurrence and early intrahepatic recurrence and could guide the surgeon’s selection of treatment strategies for hepatocellular carcinoma patients.  相似文献   
84.
85.
86.
Transgenic expression in medaka of the Xiphophorus oncogene xmrk, under a pigment cell specific mitf promoter, induces hyperpigmentation and pigment cell tumors. In this study, we crossed the Hd-rR and HNI inbred strains because complete genome information is readily available for molecular and genetic analysis. We prepared an Hd-rR (p53+/−, p53−/−) and Hd-rR HNI hybrid (p53+/−) fish-based xmrk model system to study the progression of pigment cells from hyperpigmentation to malignant tumors on different genetic backgrounds. In all strains examined, most of the initial hyperpigmentation occurred in the posterior region. On the Hd-rR background, mitf:xmrk-induced tumorigenesis was less frequent in p53+/− fish than in p53−/− fish. The incidence of hyperpigmentation was more frequent in Hd-rR/HNI hybrids than in Hd-rR homozygotes; however, the frequency of malignant tumors was low, which suggested the presence of a tumor suppressor in HNI genetic background fish. The effects on tumorigenesis in xmrk-transgenic immature medaka of a single 1.3 Gy irradiation was assessed by quantifying tumor progression over 4 consecutive months. The results demonstrate that irradiation has a different level of suppressive effect on the frequency of hyperpigmentation in purebred Hd-rR compared with hybrids.  相似文献   
87.
This study aimed to research the post-treatment quality of life (QOL) between radiotherapy (RT)- and operation (OP)-treated early cervical cancer survivors, using separate questionnaires for physicians and patients. We administered an observational questionnaire to patients aged 20–70 years old with Stages IB1–IIB cervical cancer who had undergone RT or OP and without recurrence as outpatients for ≥6 months after treatment. We divided 100 registered patients equally into two treatment groups (n = 50 each). The average age was 53 and 44 years in the RT and OP groups, respectively. The RT group included 34 and 66% Stage I and II patients, respectively, whereas the OP group included 66 and 34% Stage I and II patients, respectively. The OP group included 58% of patients with postoperative RT. Combination chemotherapy was performed in 84 and 48% of patients in the RT and OP groups, respectively. On the physicians’ questionnaire, we observed significant differences in bone marrow suppression (RT) and leg edema (OP). On the patients’ questionnaire, significantly more patients had dysuria and leg edema in the OP group than in the RT group, and severe (Score 4–5) leg edema was significantly higher in the post-operative RT group than in the OP only group. The frequency of sexual intercourse decreased after treatment in both groups. On the patients’ questionnaire, there were no significant differences between the two groups regarding sexual activity. These findings are useful to patients and physicians for shared decision-making in treatment choices. The guidance of everyday life and health information including sexual life after treatment is important.  相似文献   
88.
89.
90.
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