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   2618篇
  免费   134篇
  国内免费   26篇
耳鼻咽喉   50篇
儿科学   64篇
妇产科学   27篇
基础医学   309篇
口腔科学   59篇
临床医学   225篇
内科学   561篇
皮肤病学   48篇
神经病学   256篇
特种医学   188篇
外科学   428篇
综合类   14篇
一般理论   1篇
预防医学   109篇
眼科学   23篇
药学   149篇
中国医学   1篇
肿瘤学   266篇
  2023年   6篇
  2022年   26篇
  2021年   41篇
  2020年   26篇
  2019年   39篇
  2018年   39篇
  2017年   36篇
  2016年   56篇
  2015年   61篇
  2014年   78篇
  2013年   96篇
  2012年   193篇
  2011年   197篇
  2010年   140篇
  2009年   125篇
  2008年   209篇
  2007年   251篇
  2006年   242篇
  2005年   189篇
  2004年   191篇
  2003年   158篇
  2002年   145篇
  2001年   22篇
  2000年   26篇
  1999年   26篇
  1998年   19篇
  1997年   20篇
  1996年   10篇
  1995年   12篇
  1994年   3篇
  1993年   7篇
  1992年   10篇
  1991年   11篇
  1990年   11篇
  1989年   7篇
  1988年   5篇
  1987年   5篇
  1986年   6篇
  1985年   2篇
  1984年   2篇
  1982年   3篇
  1976年   2篇
  1973年   2篇
  1972年   4篇
  1970年   1篇
  1969年   4篇
  1968年   1篇
  1967年   2篇
  1966年   1篇
  1936年   2篇
排序方式: 共有2778条查询结果,搜索用时 0 毫秒
61.
We investigated morphometric brain changes in patients with Parkinson's disease (PD) that are associated with balance training. A total of 20 patients and 16 healthy matched controls learned a balance task over a period of 6 weeks. Balance testing and structural magnetic resonance imaging were performed before and after 2, 4, and 6 training weeks. Balance performance was re-evaluated after ∼20 months. Balance training resulted in performance improvements in both groups. Voxel-based morphometry revealed learning-dependent gray matter changes in the left hippocampus in healthy controls. In PD patients, performance improvements were correlated with gray matter changes in the right anterior precuneus, left inferior parietal cortex, left ventral premotor cortex, bilateral anterior cingulate cortex, and left middle temporal gyrus. Furthermore, a TIME × GROUP interaction analysis revealed time-dependent gray matter changes in the right cerebellum. Our results highlight training-induced balance improvements in PD patients that may be associated with specific patterns of structural brain plasticity. In summary, we provide novel evidence for the capacity of the human brain to undergo learning-related structural plasticity even in a pathophysiological disease state such as in PD.  相似文献   
62.
63.
Reports on pediatric low-grade diffuse glioma WHO-grade II (DG2) suggest an impaired survival rate, but lack conclusive results for genetically defined DG2-entities. We analyzed the natural history, treatment and prognosis of DG2 and investigated which genetically defined sub-entities proved unfavorable for survival. Within the prospectively registered, population-based German/Swiss SIOP-LGG 2004 cohort 100 patients (age 0.8-17.8 years, 4% neurofibromatosis [NF1]) were diagnosed with a DG2. Following biopsy (41%) or variable extent of resection (59%), 65 patients received no adjuvant treatment. Radiologic progression or severe neurologic symptoms prompted chemotherapy (n = 18) or radiotherapy (n = 17). Multiple lines of salvage treatment were necessary for 19/35 patients. Five years event-free survival dropped to 0.44, while 5 years overall survival was 0.90 (median observation time 8.3 years). Extensive genetic profiling of 65/100 DG2 identified Histone3-K27M-mutation in 4, IDH1-mutation in 11, BRAF-V600-mutation in 12, KIAA1549-BRAF-fusions in 6 patients, while the remaining 32 tumor tissues did not show alterations of these genes. Progression to malignant glioma occurred in 12 cases of all genetically defined subgroups within a range of 0.5 to 10.8 years, except for tumors carrying KIAA1549-BRAF-fusions. Histone3-K27M-mutant tumors proved uniformly fatal within 0.6 to 2.4 years. The current LGG treatment strategy seems appropriate for all DG2-entities, with the exemption of Histone3-K27M-mutant tumors that require a HGG-related treatment strategy. Our data confirm the importance to genetically define pediatric low-grade diffuse gliomas for proper treatment decisions and risk assessment.  相似文献   
64.
Subanesthetic administration of ketamine is a pharmacological model to elicit positive and negative symptoms of psychosis in healthy volunteers. We used resting‐state pharmacological functional MRI (rsPhfMRI) to identify cerebral networks affected by ketamine and compared them to the functional connectivity (FC) in schizophrenia. Ketamine can produce sedation and we contrasted its effects with the effects of the anxiolytic drug midazolam. Thirty healthy male volunteers (age = 19–37 years) underwent a randomized, three‐way, cross‐over study consisting of three imaging sessions, with 48 hr between sessions. A session consisted of a control period followed by infusion of placebo or ketamine or midazolam. The ENIGMA rsfMRI pipeline was used to derive two long‐distance (seed‐based and dual‐regression) and one local (regional homogeneity, ReHo) FC measures. Ketamine induced significant reductions in the connectivity of the salience network (Cohen's d: 1.13 ± 0.28, p = 4.0 × 10?3), auditory network (d: 0.67 ± 0.26, p = .04) and default mode network (DMN, d: 0.63 ± 0.26, p = .05). Midazolam significantly reduced connectivity in the DMN (d: 0.77 ± 0.27, p = .03). The effect sizes for ketamine for resting networks showed a positive correlation (r = .59, p = .07) with the effect sizes for schizophrenia‐related deficits derived from ENIGMA's study of 261 patients and 327 controls. Effect sizes for midazolam were not correlated with the schizophrenia pattern (r = ?.17, p = .65). The subtraction of ketamine and midazolam patterns showed a significant positive correlation with the pattern of schizophrenia deficits (r = .68, p = .03). RsPhfMRI reliably detected the shared and divergent pharmacological actions of ketamine and midazolam on cerebral networks. The pattern of disconnectivity produced by ketamine was positively correlated with the pattern of connectivity deficits observed in schizophrenia, suggesting a brain functional basis for previously poorly understood effects of the drug.  相似文献   
65.
66.
劈离式肝移植中供肝分离的手术经验   总被引:3,自引:0,他引:3  
目的探讨劈离式肝移植中供肝分离的手术经验。方法自2004年3月1日至9月1日,共计施行了10例体外供肝的劈离,将其分为左肝外侧叶(Ⅱ、Ⅲ段)和扩大右半肝(Ⅰ、Ⅳ~Ⅷ段)两部分,并为19位病人施行了劈离式肝移植。供体的平均年龄为32.7岁(15~51岁),平均体重64.5kg(45-75kg),ICU平均救治时间为2.4d(1~8d)。结果劈离前整体供肝和劈离后左肝外侧叶的平均重量分别为1322.6g(956~1665g)和281.8g(198~373g),后者与前者的平均比值为0.215(0.178~0.274)。左肝外侧叶部分的移植物与受体重量比(GRWR)的平均值为2.44%(1.22%~5.41%),而扩大右半肝部分GRWR的平均值为1.73%(1.31%~2.30%)。供肝劈离平均花费的时间为105min(85-135min)。共出现5例解剖变异,包括左肝静脉变异2例、肝动脉变异2例、胆管变异1例。结论劈离式肝移植已经成为扩大供肝来源的一种成熟的外科技术,且效果满意。在供肝劈离中需要正确应对各种可能的解剖变异,尤其是左肝静脉、左肝动脉和胆管的变异。  相似文献   
67.
Rossaint  J.  Margraf  A.  Zarbock  A. 《Der Anaesthesist》2019,68(7):421-427
Die Anaesthesiologie - Chirurgische Eingriffe und invasive Verfahren können beim Patienten eine inflammatorische Reaktion auslösen. Diese entzündliche Reaktion ist eine...  相似文献   
68.
Wiener Medizinische Wochenschrift - Nearly all paediatric patients require deep sedation when undergoing bone marrow aspiration (BMA). We analyzed the data from our protocols documented in...  相似文献   
69.
A new anti-macrophage monoclonal antibody (PG-M1) was produced by immunizing BALB/c mice with fresh spleen cells from a patient with Gaucher's disease. PG-M1 reacts strongly with a fixative-resistant epitope of an intracytoplasmic molecule, selectively expressed by virtually all macrophages of the human body. Although attempts to immunoprecipitate the molecule recognized by PG-M1 have failed so far, the reactivity of the antibody with COS-1 and WOP cells transfected with a human complementary DNA clone encoding for the CD68 antigen suggests that PG-M1 is a new member of the CD68 cluster. However, unlike other CD68 antibodies (KP1, EBM11, etc.), which react with both macrophages and myeloid cells, PG-M1 detects a fixative-resistant epitope on the macrophage-restricted form of the CD68 antigen. In 957 routinely fixed, paraffin-embedded samples, PG-M1 showed a more restricted reactivity with elements of the monocyte/macrophage lineage than the previously described monoclonal antibodies MAC-387 (anti-calgranulins), KP1 (CD68) and Ki-M1P. Among hematological malignancies, PG-M1 only labels acute leukemias of M4 and M5 type and rare examples of malignant histiocytosis/true histiocytic sarcoma. In contrast, acute leukemias of the M1, M2, M3, M6, M7, and L1-L3 types, non-Hodgkin's lymphomas, and Hodgkin and Reed-Sternberg cells of Hodgkin's disease are consistently PG-M1-negative. In the daily diagnostic practice, PG-M1 seems to be particularly valuable for the diagnosis of myelomonocytic or monocytic leukemia and neoplasms of true histiocytic origin in routine paraffin sections.  相似文献   
70.
Arterio-venous fistulas may develop spontaneously, following trauma or infection, or be iatrogenic in nature. We present a rare case of a jejunal arterio- venous fistula in a 35-year-old man with a history of pancreatic head resection that had been performed two years previously because of chronic pancreatitis. The patient was admitted with acute upper abdominal pain, vomiting and an abdominal machinery-type bruit. The diagnosis of a jejunal arterio-venous fistula was established by MR imaging. Transfemoral angiography was performed to assess the possibility of catheter embolization. The angiographic study revealed a small aneurysm of the third jejunal artery, abnormal early filling of dilated jejunal veins and marked filling of the slightly dilated portal vein (13–14 mm). We considered the presence of segmental portal hypertension. The patient was treated with coil embolization in the same angiographic session. This case report demonstrates the importance of auscultation of the abdomen in the initial clinical examination. MR imaging and color Doppler ultrasound are excellent noninvasive tools in establishing the diagnosis. The role of interventional radiological techniques in the treatment of early portal hypertension secondary to jejunal arterio-venous fistula is discussed at a time when this condition is still asymptomatic. A review of the current literature is included.Fax 0041 31 6324874  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