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   1513篇
  免费   48篇
  国内免费   3篇
耳鼻咽喉   17篇
儿科学   82篇
妇产科学   28篇
基础医学   151篇
口腔科学   46篇
临床医学   167篇
内科学   287篇
皮肤病学   36篇
神经病学   89篇
特种医学   292篇
外科学   139篇
综合类   17篇
预防医学   70篇
眼科学   16篇
药学   72篇
中国医学   1篇
肿瘤学   54篇
  2023年   7篇
  2022年   14篇
  2021年   23篇
  2020年   10篇
  2018年   27篇
  2017年   19篇
  2016年   16篇
  2015年   18篇
  2014年   35篇
  2013年   40篇
  2012年   43篇
  2011年   34篇
  2010年   52篇
  2009年   55篇
  2008年   51篇
  2007年   37篇
  2006年   41篇
  2005年   35篇
  2004年   34篇
  2003年   31篇
  2002年   34篇
  2001年   24篇
  2000年   21篇
  1999年   26篇
  1998年   53篇
  1997年   71篇
  1996年   55篇
  1995年   42篇
  1994年   55篇
  1993年   56篇
  1992年   19篇
  1991年   22篇
  1990年   23篇
  1989年   39篇
  1988年   45篇
  1987年   37篇
  1986年   34篇
  1985年   31篇
  1984年   14篇
  1983年   25篇
  1982年   21篇
  1981年   21篇
  1980年   25篇
  1979年   10篇
  1978年   12篇
  1977年   23篇
  1976年   24篇
  1975年   23篇
  1973年   14篇
  1972年   6篇
排序方式: 共有1564条查询结果,搜索用时 739 毫秒
41.
Mandibular pseudocarcinomatous hyperplasia   总被引:5,自引:0,他引:5  
AIMS: Three unusual cases of pseudocarcinomatous (pseudoepitheliomatous) hyperplasia (PH) affecting chronic osteomyelitic mandibular sequestra are reported to highlight the differences with the various squamous neoplasms which occur in that site. METHODS AND RESULTS: In two patients carrying a mandibular graft following the excision of an ameloblastoma, mucosal ulcers resulted in chronic osteomyelitis. In a third patient, an apical dental infection was associated with fistulated osteomyelitis. Histology of the three sequestra showed an intraosseous squamous proliferation. It was characterized by a peripheral involvement of medullary spaces, the more mature epithelial layer covering the bone trabeculae without intervening stroma, and the basal type epithelial layer surrounding a central fibrovascular core. There were no histological or cytological signs of malignancy. CONCLUSION: PH shows an inverted pattern when compared with the centro-medullary tumoural islands seen in the various oral or odontogenic squamous neoplasms which occur in the jaws. The lack of signs of malignancy distinguish PH from common squamous cell carcinomas. A short clinical course is an important feature in the distinction of PH from the well differentiated squamous cell carcinomas which may develop in fistulated chronic osteomyelitis.  相似文献   
42.
PURPOSE: This study was conducted to perform kinematic measures in a group of asymptomatic professional baseball pitchers to determine side-to-side differences in passive glenohumeral range of motion (ROM) and stiffness. We hypothesized that the throwing shoulder in asymptomatic pitchers would display greater passive glenohumeral stiffness than the contralateral nonthrowing shoulder. METHODS: Thirty-four professional baseball pitchers had bilateral assessments for passive glenohumeral ROM and stiffness during a single test session. ROM and stiffness measures were obtained objectively using standard goniometry and instrumented stress arthrometry, respectively. RESULTS: The throwing shoulder had significantly less (-8.5 degrees) internal rotation and significantly more external rotation (5.1 degrees) than the nonthrowing shoulder (P < 0.01). Passive joint stiffness was not significantly different between the throwing and nonthrowing shoulder, and anterior joint stiffness was significantly greater than posterior joint stiffness for both shoulders (P < 0.05). CONCLUSIONS: The repetitive stress of long-term throwing creates altered glenohumeral rotational patterns in the throwing shoulder of the professional baseball pitcher without compromising the joint's passive restraining quality.  相似文献   
43.
COVID-19 has been sweeping the globe, hitting the United States particularly hard with a state of emergency declared on March 13, 2020. Transplant hospitals have taken various precautions to protect patients from potential exposure. OPTN donor, candidate, and transplant data were analyzed from January 5, 2020 to September 5, 2020. The number of new waiting list registrations decreased, with the Northeast seeing over a 50% decrease from the week of 3/8 versus the week of 4/5. The national transplant system saw near cessation of living donor transplantation (−90%) from the week of 3/8 to the week of 4/5. Similarly, deceased donor kidney transplant volume dropped from 367 to 202 (−45%), and other organs saw similar decreases: lung (−70%), heart (−43%), and liver (−37%). Deceased donors recovered dropped from 260 to 163 (−45%) from 3/8 compared to 4/5, including a 67% decrease for lungs recovered. The magnitude of this decrease varied by geographic area, with the largest percent change (−67%) in the Northeast. Despite the pandemic, discard rates across organ has remained stable. Although the COVID-19 pandemic continues to evolve, OPTN data show recent evidence of stabilization, an indication that an early recovery of the number of living and deceased donors and transplants has ensued.  相似文献   
44.
Biochemical and immunological properties of dog brain isorenin   总被引:3,自引:0,他引:3  
A Husain  R R Smeby  D Wilk  V J Dzau  F M Bumpus 《Endocrinology》1984,114(6):2210-2215
A neutral protease with angiotensin I-forming activity which could readily be separated from acid proteases and plasma and renal renin was obtained from extracts of dog brain. This enzyme has an apparent mol wt of 40,000 by Sephadex chromatography. On chromatofocusing, it displays isoelectric points of 7.92, 7.73, and 7.42, and thus, it is a basic protein, in contrast to either renal or plasma renin which are acidic proteins. This brain enzyme does not react with antibodies specific for dog kidney renin. Since the brain enzyme forms angiotensin I from renin substrate at neutral pH, yet can be separated from and has isoelectric points different from renal renin, it is an isoenzyme of the kidney counterpart. The majority of the renin-like activity of dog brain is due to this isoenzyme.  相似文献   
45.
46.
Formation of metastases in the lungs is the major cause of death in patients suffering from osteosarcoma (OS). Metastases at presentation and poor response to preoperative chemotherapy are strong predictors for poor patient outcome. The elucidation of molecular markers that promote metastasis formation and/or chemoresistance is therefore of importance. CD44 is a plasma membrane glycoprotein that binds to the extracellular matrix component hyaluronan (HA) and has been shown to be involved in metastasis formation in a variety of other tumors. Here we investigated the role of CD44 expression on OS tumor formation and metastasis. High CD44 expression, evaluated with a tissue microarray including samples from 53 OS patients and stained with a pan‐CD44 antibody (Hermes3), showed a tendency (p < 0.08) to shortened overall survival. However, nonresponders and patients with lung metastases and high CD44 expression had significantly poorer prognosis than patients with low CD44 expression. Overexpression of the standard CD44 isoform (CD44s) and its HA‐binding defective mutant R41A in osteoblastic SaOS‐2 cells resulted in HA‐independent higher migration rates and increased chemoresistance, partially dependent on HA. In an orthotopic mouse model of OS, overexpression of CD44s in SaOS‐2 cells resulted in an HA‐dependent increased primary tumor formation and increased numbers of micrometastases and macrometastases in the lungs. In conclusion, although CD44 failed to be an independent predictor for patient outcome in this limited cohort of OS patients, increased CD44 expression was associated with even worse survival in patients with chemoresistance and with lung metastases. CD44‐associated chemoresistance was also observed in vitro, and increased formation of lung metastases was found in vivo in SCID mice. © 2013 American Society for Bone and Mineral Research.  相似文献   
47.
48.
A double-blind, placebo-controlled randomized trial of 13-cis retinoic acid was performed to determine if the drug has a therapeutic effect in patients with myelodysplastic syndromes (MDS). Sixty-eight evaluable patients with MDS were randomized to receive a single, daily oral dose of either 13-cis retinoic acid (13-CRA, 100 mg/m2) or matching placebo. Treatment was continued, when possible, for a period of 6 months. Determination of response to treatment was based on clinical course, repeat bone marrow biopsies, and aspirates and blood counts (CBC) with WBC differential, platelet, and reticulocyte numbers at specified intervals. No significant difference was noted between the two treatment groups in response to test drug (P = .66). One patient (3%) in the 13-CRA group and two patients (6%) in the placebo group had a minor response. Approximately 30% of patients in both groups had progression of their disease, and progression-free survival was nearly identical. Greater than 90% of the patients receiving 13-CRA developed mild or moderate skin toxicity that was reversible with decreasing or discontinuing the drug. Our study did not find that 13-CRA exerts a beneficial therapeutic effect in patients with MDS.  相似文献   
49.
50.
OBJECTIVE: The purpose of this study was to assess the effects of patients' awareness of their illness on the clinical presentation, management, and course of nonadherence to antipsychotic medications among patients with schizophrenia. METHODS: A national survey was conducted of psychiatrists who were treating patients with schizophrenia. The survey was sent to 771 psychiatrists, of whom 534 responded, for a response rate of 69 percent. The psychiatrists were asked to report on presentation, management, and course for one adult patient with schizophrenia who had been under their care for at least one year and who had been nonadherent to oral antipsychotics at some point in the past year. Patients who were aware that they had a mental illness were compared with those who were not aware. RESULTS: Of the 534 respondent psychiatrists, 310 reported on an eligible patient, and 300 of these patients were classified by illness awareness. Ninety-seven patients, or 32 percent, were not aware that they had a mental illness. These patients who lacked awareness had significantly longer episodes of antipsychotic nonadherence, were more likely to completely cease taking the antipsychotic medication, were more likely to have severe positive symptoms, and were more likely to be psychiatrically hospitalized after nonadherence than those who were aware of their illness. Psychological interventions and several types of family interventions were significantly less effective among patients who lacked awareness. CONCLUSIONS: A lack of awareness of mental illness is common among patients with schizophrenia who are nonadherent to antipsychotics. Such nonadherence tends to be especially disruptive and unresponsive to simple commonly used psychological interventions.  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