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   1886篇
  免费   57篇
  国内免费   3篇
耳鼻咽喉   7篇
儿科学   18篇
妇产科学   38篇
基础医学   204篇
口腔科学   24篇
临床医学   104篇
内科学   567篇
皮肤病学   7篇
神经病学   214篇
特种医学   64篇
外科学   264篇
综合类   7篇
预防医学   41篇
眼科学   16篇
药学   137篇
中国医学   5篇
肿瘤学   229篇
  2022年   18篇
  2021年   16篇
  2018年   15篇
  2017年   15篇
  2016年   21篇
  2015年   17篇
  2014年   23篇
  2013年   36篇
  2012年   60篇
  2011年   53篇
  2010年   43篇
  2009年   42篇
  2008年   72篇
  2007年   60篇
  2006年   89篇
  2005年   71篇
  2004年   67篇
  2003年   68篇
  2002年   81篇
  2001年   88篇
  2000年   86篇
  1999年   71篇
  1998年   22篇
  1997年   23篇
  1996年   25篇
  1995年   15篇
  1994年   20篇
  1993年   19篇
  1992年   54篇
  1991年   51篇
  1990年   49篇
  1989年   43篇
  1988年   56篇
  1987年   48篇
  1986年   50篇
  1985年   37篇
  1984年   34篇
  1983年   35篇
  1982年   13篇
  1981年   14篇
  1979年   31篇
  1978年   16篇
  1977年   17篇
  1976年   14篇
  1974年   11篇
  1972年   15篇
  1969年   13篇
  1968年   14篇
  1967年   11篇
  1966年   11篇
排序方式: 共有1946条查询结果,搜索用时 0 毫秒
81.
Increasing recipient age is a well-known risk factor for graft-versus-host disease (GVHD) and treatment-related mortality (TRM) and has a negative impact on allogeneic hematopoietic stem cell transplantation. Since the incidence of severe GVHD after cord blood transplantation (CBT) is lower than that after transplants using bone marrow or mobilized peripheral blood grafts from adult cells, we should expect better outcomes from CBT in older patients. To evaluate the feasibility and efficacy of myeloablative unrelated CBT in patients aged between 50 and 55 years, we performed a retrospective comparison of 100 patients with acute leukemia who received cord blood grafts at our institution. Nineteen older patients (median age, 52; range, 50–55) and 81 younger patients (median, 36; range, 16–49) received a myeloablative conditioning regimen including 12 Gy of total body irradiation and chemotherapy. GVHD prophylaxis included cyclosporine with (n = 96) or without (n = 4) methotrexate. There were no significant differences in the incidences of grades II to IV acute GVHD, extensive-type chronic GVHD, TRM, and the probability of overall and disease-free survival between these groups. These results suggest that, in patients with acute leukemia, myeloablative CBT might be as safe and effective in patients aged between 50 and 55 years as in younger patients.  相似文献   
82.
Renal cell carcinoma (RCC) producing α-fetoprotein (AFP) is a rare entity and merely 7 cases have been reported so far. The present case, a 71-year-old woman, showed a high serum AFP level of 204 ng/ml. The RCC of the autopsied right kidney consisted mainly of spindle-shaped or bizarre sarco-matous tumor cells. AFP was immunolocalized only in the concomitant clear cell component. Concanavalin A (Con A)-nonadsorption rate of serum AFP was 42%, which was an intermediate value between those of yolk sac tumors and metastatic liver carcinomas. Lens culinalis agglutinin (LCA)-affinity study of the patient's AFP showed an unknown peak X, which was eluted between the known peaks 2 and 3. These results suggest a certain structural alteration in carbohydrate moieties of the AFP derived from this RCC. A review of the clincopathologic features of 8 patients with AFP-producing RCC was made to understand the pathophysiology of AFP-producing neoplasms. © Wiley-Liss, Inc.  相似文献   
83.
84.
Anastomotic insufficiency is considered to be one of the most serious complications associated with esophageal reconstruction. The purposes of this study were to identify (1) the relationship between anastomotic insufficiency and tissue blood flow (TBF) in the gastric tube in the perioperative period, and (2) the effects of intravenous prostaglandin E1 (PGE1) on TBF in the gastric tube. The study group consisted of 44 patients who were to undergo esophagectomy for esophageal cancer. Intraoperative and postoperative TBF on the serosal side of the gastric tube were measured by laser-Doppler tissue blood flowmetry. The TBF of the Leakage(+) group (n = 5) was poorer than that of the Leakage(?) group (n = 39) during the intraoperative and postoperative periods. There was a significant difference in TBF between the two groups at postoperative day (POD) 3. There was a tendency in the PGE1(+) group (n = 18) to exhibit richer blood flow through the anastomosis than the PGE1(?) group (n = 26), intraoperatively, but the difference was not significant. Two of five Leakage(+) cases were also in the PGE1(+) group. There was no relationship between intraoperative medication with PGE1 and incidence of leakage. The TBF of three-field lymph node dissection and reconstruction of the retrosternal route group (n = 21) was poorer than that of the two-field lymph-node dissection and reconstruction of the posterior mediastinal route group (n = 23). The TBF in the gastric tube after esophagectomy may be a predictor of anastomotic insufficiency. However, PGE1 treatment in the intraoperative period alone is not effective in preventing anastomotic insufficiency.  相似文献   
85.
OBJECTIVE: The authors examined dopamine transporter density in the orbitofrontal cortex, dorsolateral prefrontal cortex, and amygdala in methamphetamine users and assessed the relationship of these measures to the subjects' clinical characteristics. METHOD: Positron emission tomography with [(11)C]WIN 35,428 was used to examine the regions of interest in 11 methamphetamine users and nine healthy comparison subjects. Psychiatric symptoms were evaluated with the Brief Psychiatric Rating Scale. RESULTS: Dopamine transporter density in the three regions studied was significantly lower in the methamphetamine users than in the comparison subjects. The lower dopamine transporter density in the orbitofrontal and dorsolateral prefrontal cortex was significantly correlated with the duration of methamphetamine use and the severity of psychiatric symptoms. CONCLUSIONS: Chronic methamphetamine use may cause dopamine transporter reduction in the orbitofrontal cortex, dorsolateral prefrontal cortex, and amygdala in the brain. Psychiatric symptoms in methamphetamine users may be attributable to the decrease in dopamine transporter density in the orbitofrontal cortex and the dorsolateral prefrontal cortex.  相似文献   
86.
The present study demonstrated the age-related changes in the striatal dopamine D1 receptor binding and its related cAMP second-messenger system in the living brains of conscious young (6.4 +/- 1.8 years old) and aged (19.5 +/- 3.3 years old) monkeys (Macaca mulatta) using positron emission tomography (PET). For quantitative analysis of D1 receptors, [11C]SCH23390 was used and phosphodiesterase type-IV (PDE-IV) activity, as an index of cAMP system, was estimated by two scans with R- and S-[11C]rolipram. Significant age-related decreases in D1 receptor binding were observed in the striatum and frontal cortex. Analysis of uptake of R- and S-[11C]rolipram indicated age-related decreases in PDE-IV activity showing 22.0 and 25.2% decreases in the striatum and frontal cortex, respectively, while no significant changes were observed in the cerebellum. With systemic preadministration of the dopamine D1 receptor antagonist SCH23390 (0.2, 0.6, and 2 mg/kg), the PDE-IV activities in the striatum and frontal cortex were dose-dependently suppressed in both age groups. However, the degree of suppression by SCH23390 was more marked in young than in aged monkeys. These results demonstrate that the striatal cAMP second-messenger system activity as well as its functional response to dopamine D1 antagonist showed age-related impairment in the brain.  相似文献   
87.
BACKGROUND: Glucose transporter (Glut) proteins, which are membrane proteins responsible for the transport of glucose across cellular membranes, have six forms. To further elucidate the role of Glut-1 expression in esophageal squamous cell carcinoma, we examined the expression of Glut-1 protein immunohistochemically. MATERIALS AND METHODS: Immunohistochemical expression of Glut-1 was examined in surgically resected tissues from 95 patients with esophageal squamous cell carcinoma. RESULTS: Of the 95 esophageal carcinomas, 91 (95.8%) had some Glut-1 immunostaining in the membranes of the cancer cells. Positive staining (> 30% of cancer cells showing Glut-1 expression) was observed in 49 (51.6%) of the cases. Comparison of Glut-1 expression and clinicopathological characteristics in the 95 patients with esophageal cancer revealed significant associations between Glut-1 expression and tumor status (p < 0.001), lymph node status (p < 0.05), metastatic status (p < 0.01), and pathological stage (p < 0.001). The survival rates of patients with Glut-1-positive tumors were significantly lower than those of patients with Glut-1-negative tumors (log-rank p < 0.05). CONCLUSION: In conclusion, the level of Glut-1 expression may be a useful marker that can provide information on tumor aggressiveness and prognosis in patients with esophageal squamous cell carcinoma.  相似文献   
88.
A long-lasting dizzy sensation is a common complaint in elderly subjects. The pathogenesis and effective treatment of such chronic dizziness (CD), however, have not yet been fully elucidated because of lack of methods for evaluating this sensation. On the basis of assumption that CD may be attributable partly to cortical functional abnormality, we attempted to estimate the function of auditory cortex by measurements of auditory-evoked magnetic fields (AEFs). Magnetic field signals in the parieto-temporal cortex were evoked by 1000-Hz tone-burst with 90-dB normal hearing level sounds, and the highest-amplitude magnetic waveforms at approximately 100-ms (N100m) were analyzed as electrical current arrows in normal subjects (n=11), patients with CD (n=27) and patients with cerebral infarction but no dizzy sensation (n=9). In the normal subjects, the current arrows pointed to a nearly straight line with small directional distortion as indicated by a rotation-degree parameter, dI(rot) of 1.59+/-0.46. In 17 of 27 CD patients, the directions of current arrows were markedly distorted showing abnormally high dI(rot) values greater than 2.50 (the mean plus two standard deviations of normal values) and disclosed a clockwise or counter-clockwise rotation in either side or both sides of parieto-temporal cortex. In all the patients with cerebral infarction, the current arrows exhibited the similar pattern as the normal subjects. None of them exhibited abnormally high dI(rot) values. We hypothesized that the rotational abnormality may be caused by abnormal neuronal excitation, since non-evoked magnetic fields in temporal lobe epilepsy demonstrated the similar current rotational abnormality as reported previously. Seven CD patients were treated with anticonvulsants, and four showed remarkable amelioration of dizzy sensation. In all the four patients with symptomatic amelioration, the disappearance of rotational abnormality in AEFs or the tendency towards disappearance was observed following symptomatic amelioration. The results of the present study suggest that the auditory center may contribute to the maintenance of equilibrium, and its dysfunction may lead to the development of CD. AEFs measurements may make it possible to evaluate the functional abnormality of auditory center and may be useful for studying the pathophysiology and treatment of CD.  相似文献   
89.
90.
We experienced a rare case of endotracheal metastasis derived from squamous cell lung cancer. The patient was 56 year-old male whose primary lung cancer of the left upper lobe was completely resected. Pathological diagnosis indicated stage IIB and he underwent two cycles of chemotherapy with CDDP + VDS. He had been asymptomatic thereafter, however, two years postoperative chest CT revealed a nodular lesion of the anterior carinal wall. Bronchofiberoptic examination showed same as CT finding and its brushing cytology confirmed squamous cell carcinoma. WE successfully resected his endotracheal metastatic lesion and reconstructed by direct sutures assisted by PCPS (Percutaneous Cardiopulmonary Support System). His postoperative course was uneventful. Majority of the reported cases of endotracheal metastases were treated conservatively as radiation, laser and/or chemotherapy. We conclude that PCPS is useful device for surgical management for selected cases.  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