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   2432篇
  免费   191篇
  国内免费   5篇
耳鼻咽喉   69篇
儿科学   62篇
妇产科学   84篇
基础医学   481篇
口腔科学   13篇
临床医学   154篇
内科学   535篇
皮肤病学   28篇
神经病学   258篇
特种医学   68篇
外科学   338篇
综合类   15篇
一般理论   1篇
预防医学   200篇
眼科学   84篇
药学   88篇
中国医学   1篇
肿瘤学   149篇
  2023年   19篇
  2022年   24篇
  2021年   49篇
  2020年   34篇
  2019年   54篇
  2018年   42篇
  2017年   35篇
  2016年   57篇
  2015年   48篇
  2014年   42篇
  2013年   65篇
  2012年   121篇
  2011年   120篇
  2010年   72篇
  2009年   66篇
  2008年   132篇
  2007年   98篇
  2006年   131篇
  2005年   120篇
  2004年   122篇
  2003年   86篇
  2002年   76篇
  2001年   68篇
  2000年   63篇
  1999年   66篇
  1998年   31篇
  1997年   29篇
  1996年   15篇
  1995年   23篇
  1994年   17篇
  1993年   19篇
  1992年   42篇
  1991年   41篇
  1990年   44篇
  1989年   63篇
  1988年   35篇
  1987年   40篇
  1986年   34篇
  1985年   29篇
  1984年   40篇
  1983年   20篇
  1980年   16篇
  1979年   32篇
  1978年   14篇
  1977年   17篇
  1975年   17篇
  1974年   18篇
  1973年   15篇
  1969年   17篇
  1968年   12篇
排序方式: 共有2628条查询结果,搜索用时 15 毫秒
21.
There are conflicting reports about estrogen modulating the activity of nigrostriatal dopaminergic neurons. Furthermore, modulation may be influenced by progesterone levels. Therefore, the clinical effects of sex steroids on parkinsonian symptoms in postmenopausal women with Parkinson's disease (PD) were analyzed in the present study. Patients (n = 12) were under the age of 80, able to perform the motor function tests, and showed no contraindications for estrogen suppletion. Motor function was assessed using the Unified Parkinson's Disease Rating Scale (UPDRS) and a patient interview on subjective changes. In a placebo-controlled, randomized, double-blind trial lasting 8 weeks, no significant dopaminergic effect of estradiol (E2) could be demonstrated, whereas in an open trial phase lasting 2 weeks, progesterone seemed to have an antidopaminergic effect. Several mechanisms are discussed that can account for the fact that we found no effect of E2 on motor functioning in our patients with PD.  相似文献   
22.
Systemic administration of the mitochondrial toxin 3-nitropropionic acid (3-NP) to rats results in selective striatal lesions and serves as an experimental model of Huntington's disease (HD). However, the effects of the 3-NP treatment are unpredictable and result in lesions of variable severity. The present study was aimed at further characterizing the variability of the striatal lesions induced by systemic administration of 3-NP using osmotic pumps. Hematoxylin-eosin (HE) and Nissl stains as well as immunohistochemical labelling of astrocytes and striatal neurones were performed to analyse the neurotoxic effects of 3-NP. In general, chronic systemic administration of 3-NP resulted in obvious bilateral striatal lesions, which ranged from mild to severe, together with a subtle, but detectable behavioural lesion. Severe type lesions showed marked neuronal loss and an increased expression of glial fibrillary acidic protein (GFAP) in astrocytes surrounding the lesion area, whereas in the core of the lesion GFAP-immunoreactivity was absent. The mild type lesion was characterized by a substantial loss of striatal neurones and an increased expression of GFAP-positive astrocytes throughout the lesion. In a number of 3-NP-treated animals, neither type of lesion was observed, although these animals demonstrated behavioural changes in the paw test compared to controls. In the striatum of these tested 3-NP-treated animals, compromised rk' neurones were detected, suggestive of subtle and early 3-NP-induced neuronal injury. Similar dark neurones were also detected in mild and severe lesions and were immunocytochemically characterized as gamma-aminobutyric acid (GABA) and substance P containing spiny neurones, which belong to the neuronal population that is affected in early HD. These results indicate that systemic administration of 3-NP to rats may result in a spectrum of striatal pathology of which the morphology of the mild type lesion resembles the characteristic HD neuropathology most closely.  相似文献   
23.
24.
Quality of Life following Radical Surgical Treatment of Gastric Carcinoma   总被引:7,自引:1,他引:6  
Quality of life (QOL) in patients with gastric cancer who underwent total gastrectomy has so far not been studied using the EORTC QLQ-C30 (Quality of Life Core Questionnaire of the European Organization for Research and Treatment of Cancer) as a standardized European QOL instrument. The aim of this study was to evaluate the effect of radical procedures such as extensive lymph node resection and combined resection of adjacent organs on patients' QOL. From 1992 to 1996, 152 patients underwent total gastrectomy. All patients alive on July 1, 1996 were included in the study (77/152). For assessing QOL, the EORTC QOL questionnaire QLQ-C30 version 2.0 and a validated gastric cancer module were sent home to the patients for self-completion. The response rate was 91%. It was possible to evaluate the questionnaires of 62 patients who had undergone resection with curative intent including 13 extended gastrectomies (21%). Of the 62 resections, 50 were combined with D2 lymphadenectomy (80.6%). The global health status was not negatively influenced by D2 lymphadenectomy and extended gastrectomy. Patients with splenectomy were more affected by treatment than patients without splenectomy. Radical gastrectomy combined with D2 lymphadenectomy is the treatment of choice for gastric cancer patients, concerning not just survival but QOL as well.  相似文献   
25.
Zusammenfassung 60 gastrektomierte Patienten mit 5 Verfahren des Magenersatzes wurden nachuntersucht. Beschwerden durch einen jejuno-oesophagealen Reflux werden nur von der Patienten mit einer Jejunuminterposition geklagt. Bei der Jejunoplicatio und der Interposition findet sich endoskopisch-histologisch die Oesophagitis qualitativ und quantitativ geringer ausgeprägt. Manometrisch kann nur bei 5 von 16 Gastrektomierten ein funktionstüchtiger unterer Oesophagussphincter nachgewiesen werden. Der Sphincterverlust muß als Mitursache des Refluxes angesehen werden.  相似文献   
26.
Physician recertification poses a unique challenge to member boards of the American Board of Medical Specialties (ABMS) charged with the responsibility of credentialing physicians. The key issue that emerges in recertification programs is how to evaluate performance in practice. Although some test of knowledge may be appropriate, an evaluation of clinical performance has become essential in recertification programs. To meet this challenge, ABMS boards have adopted methods to evaluate performance in practice. However, regardless of the methods chosen, criteria are needed to serve as standards. This article considers the application of outcomes assessment in the definition of standards for recertification. When direct outcome assessment may not be possible, outcome-validated process measures may provide a suitable alternative.  相似文献   
27.
28.
PURPOSE: Prognosis of patients with glioblastoma is poor. Therefore, in glioblastoma patients, we analyzed whether antitumor vaccination with a virus-modified autologous tumor cell vaccine is feasible and safe. Also, we determined the influence on progression-free survival and overall survival and on vaccination-induced antitumor reactivity. PATIENTS AND METHODS: In a nonrandomized study, 23 patients were vaccinated and compared with nonvaccinated controls (n = 87). Vaccine was prepared from patient's tumor cell cultures by infection of the cells with Newcastle Disease Virus, followed by gamma-irradiation, and applied up to eight times. Antitumor immune reactivity was determined in skin, blood, and relapsed tumor by delayed-type hypersensitivity skin reaction, ELISPOT assay, and immunohistochemistry, respectively. RESULTS: Establishment of tumor cell cultures was successful in approximately 90% of patients. After vaccination, we observed no severe side effects. The median progression-free survival of vaccinated patients was 40 weeks (v 26 weeks in controls; log-rank test, P = .024), and the median overall survival of vaccinated patients was 100 weeks (v 49 weeks in controls; log-rank test, P < .001). Forty-five percent of the controls survived 1 year, 11% survived 2 years, and there were no long-term survivors (> or = 3 years). Ninety-one percent of vaccinated patients survived 1 year, 39% survived 2 years, and 4% were long-term survivors. In the vaccinated group, immune monitoring revealed significant increases of delayed-type hypersensitivity reactivity, numbers of tumor-reactive memory T cells, and numbers of CD8(+) tumor-infiltrating T-lymphocytes in secondary tumors. CONCLUSION: Postoperative vaccination with virus-modified autologous tumor cells seems to be feasible and safe and to improve the prognosis of patients with glioblastomas. This could be substantiated by the observed antitumor immune response.  相似文献   
29.
30.
BACKGROUND: Highly active antiretroviral treatment (HAART) reduces the risk of wasting in HIV infection and may alter the prognostic weight of wasting. The phase angle from bioelectrical impedance analysis (BIA) can be interpreted as a surrogate marker for the catabolic reaction to chronic HIV infection and opportunistic disease. OBJECTIVE: Our objective was to assess the prognostic ability of the phase angle in HIV-infected patients in the era of HAART. DESIGN: Two cross-sectional observation studies were conducted in 1996 and 1997 at a German university outpatient HIV clinic. In the 1996 and 1997 cohorts, HAART was prescribed to 17 of 212 and 168 of 257 patients at baseline and to 179 of 212 and 234 of 257 patients during observation, respectively. Whole-body BIA was assessed at 50 KHz. Time to clinical progression and survival were calculated by using Cox proportional hazard models with time-dependent covariates. Median observation times were 1000 and 515 d for the 1996 and 1997 cohorts, respectively. RESULTS: Higher phase angle was associated with a lower relative mortality risk, adjusted for viral load and CD4(+) cell count, of 0.49 (95% CI: 0.30, 0.81) per degree in 1996 and of 0.33 (95% CI: 0.18, 0.61) in 1997. The influence of phase angle on time to clinical progression, adjusted for viral load and CD4(+) cell count, was not significant in 1996 but the relative risk was 0.58 (0.36, 0.83) in 1997. CONCLUSION: Despite the favorable effects of HAART on the nutritional status of HIV-infected persons, low phase angle remains an independent adverse prognostic marker of clinical progression and survival.  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