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   1983344篇
  免费   141653篇
  国内免费   3990篇
耳鼻咽喉   28588篇
儿科学   65119篇
妇产科学   57802篇
基础医学   286879篇
口腔科学   55684篇
临床医学   168965篇
内科学   389555篇
皮肤病学   41824篇
神经病学   155833篇
特种医学   78070篇
外国民族医学   672篇
外科学   308346篇
综合类   42401篇
现状与发展   1篇
一般理论   533篇
预防医学   146265篇
眼科学   45847篇
药学   147825篇
  1篇
中国医学   3895篇
肿瘤学   104882篇
  2018年   19034篇
  2016年   16170篇
  2015年   18532篇
  2014年   26112篇
  2013年   39957篇
  2012年   54184篇
  2011年   58027篇
  2010年   34749篇
  2009年   32797篇
  2008年   55849篇
  2007年   60071篇
  2006年   60961篇
  2005年   59742篇
  2004年   57371篇
  2003年   55669篇
  2002年   54771篇
  2001年   88321篇
  2000年   90768篇
  1999年   77525篇
  1998年   22001篇
  1997年   19892篇
  1996年   19993篇
  1995年   18783篇
  1994年   17862篇
  1993年   16704篇
  1992年   61981篇
  1991年   60589篇
  1990年   59575篇
  1989年   57675篇
  1988年   53863篇
  1987年   52822篇
  1986年   50554篇
  1985年   48247篇
  1984年   36146篇
  1983年   31166篇
  1982年   18748篇
  1981年   16491篇
  1979年   34156篇
  1978年   24033篇
  1977年   20587篇
  1976年   19489篇
  1975年   21426篇
  1974年   25342篇
  1973年   24371篇
  1972年   23176篇
  1971年   21588篇
  1970年   20302篇
  1969年   19267篇
  1968年   18276篇
  1967年   16327篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
AIM: Peritonectomy procedures with intraperitoneal chemohyperthermia are an effective but costly treatment for peritoneal carcinomatosis (PC). Consequently a proper selection of patients is necessary. We evaluated the benefit of MRI prior to surgery, in the detection of two of the main surgery contraindications: bulky mesenteric tumors and bladder implants. METHODS: Three experts retrospectively reviewed abdominal and pelvic MRI from 19 cases of surgically proved PC (ovary: 7; colorectal: 7; gastric: 2; pseudomyxoma peritonei: 2; appendix: 1). RESULTS: Mesenteric tumors were always identified as hypersignal masses on axial and coronal fat suppression gadolinium-enhanced T1 images (n=3). Three out of five bladder implants were detected. The two cases of bladder implants that were not detected on MRI were missed because the bladder was not filled. The best sequence for the detection of bladder involvement was axial T2-weighted images with bladder filling. CONCLUSIONS: Evaluating the preoperative resectability of PC is crucial for patient management. MRI seems to reliably detect bulky mesenteric tumors and bladder implants on condition the bladder is filled and appropriate sequences are used.  相似文献   
992.
993.
994.
A diagnosis of sarcoidosis should be substantiated by pathological means in order to thoroughly exclude other diseases. The role of real-time endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) in the diagnosis of sarcoidosis has not been reported. The purpose of the present study is to evaluate the diagnostic yield of EBUS-TBNA in demonstrating the pathological features of sarcoidosis. In total, 65 patients with suspected sarcoidosis, with enlarged hilar or mediastinal lymph nodes on computed tomography, were included in the study. Patients with a suspected or known malignancy or previously established diagnosis of sarcoidosis were excluded. Convex probe endobronchial ultrasonography integrated with a separate working channel was used for EBUS-TBNA. Surgical methods were performed in those in whom no granulomas were detected by EBUS-TBNA. Patients were followed up clinically. EBUS-TBNA was performed on a total of 77 lymph node stations in 65 patients. A final diagnosis of sarcoidosis was made for 61 (93.8%) of the patients. The remaining four patients were diagnosed as having Wegener's granulomatosis (n=1) or indefinite (n=3). In patients with a final diagnosis of sarcoidosis, EBUS-TBNA demonstrated noncaseating epithelioid cell granulomas in 56 (91.8%) of the patients. No complications were reported. Endobronchial ultrasound-guided transbronchial needle aspiration proved to be a safe procedure with a high yield for the diagnoses of sarcoidosis.  相似文献   
995.
SETTING: Tuberculosis (TB) is frequent in human immunodeficiency virus (HIV) infected patients, but its treatment is hampered by adverse events and paradoxical reactions. OBJECTIVE: To examine the impact of HIV infection and other factors on the risk and spectrum of adverse events related to anti-tuberculosis treatment in a prospective cohort study conducted between January 2003 and August 2004. RESULTS: Of 105 patients treated for TB, 30 were HIV-infected. The overall incidence of adverse events was 122.5 +/- 18.5 per 100 patient-years (py) and the incidence of severe adverse events was 45.2 +/- 11.3/100 py. Age >50 years (OR 2.2, 95%CI 1.01-4.8, P = 0.046) and HIV infection (OR 3.9, 95%CI 2.1-7.5, P < 0.001) were independently associated with a higher risk of adverse events. Hepatitis (30.5/100 py) and neuropathy (28.6/100 py) were the most frequent adverse events. Hepatitis C virus infection was associated with hepatitis (OR 4.2, 95%CI 1.2-15.0, P = 0.028) and neuropathy with HIV infection (OR 3.8, 95%CI 1.1-13.7, P = 0.040). CONCLUSION: Adverse reactions to anti-tuberculosis drugs are frequent. HIV infection and age >50 years are factors associated with such reactions, while hepatitis C virus infection is a risk factor for hepatitis.  相似文献   
996.
Within the context of early diagnosis of Alzheimer's disease (AD), there is a growing interest in neuropsychological screening tests. Amongst these tests, we focused on the largely used Memory Impairment Screen (MIS). The objective of the present work was to show that adding a 10-min delayed recall to the MIS, improves the test psychometric characteristics in order to detect dementia in the earliest stages. A prospective study was carried out on a cohort of 270 consecutive elderly ambulatory subjects attending the Broca Hospital Memory Clinic: normal controls ( n  = 67), mild cognitive impairment subjects ( n  = 98) and mildly demented patients [ n  = 105, Mini Mental State Examination (MMSE) = 23 ± 4]. This study consisted in testing the advantage of the 10-min delayed recall entitled MIS-D compared with the MIS. At a cut-off score of 6, the MIS-D revealed satisfying psychometric characteristics with a sensitivity of 81% and a specificity of 91%, whilst the MIS alone indicated a sensitivity of 60% and a specificity of 88% in detecting dementia. In demented patients with MMSE score ≥26, MIS-D properties still remained satisfying (sensitivity: 75%, specificity: 92%). MIS-D is a more relevant screening test than MIS alone at very early stages of dementia.  相似文献   
997.
This study compared the predictive value of the theory of planned behavior in university students in South Africa (N = 251) and the United States (N = 160) who completed an anonymous self-administered questionnaire. Multiple regression analyses revealed that condom use and intention were significantly predicted by positive condom attitude, subjective norm, self-efficacy, and attending university in South Africa. Significant interactions between country and predictors indicated that subjective norm predicted condom use and intention more strongly in the American sample than in the South African sample; attitude predicted intention more strongly in the American sample than in the South African sample; but self-efficacy predicted intention more strongly in the South African sample than in the American sample. The theory of planned behavior may provide a useful framework for interventions to reduce South African students' risk of HIV/and sexuality transmitted diseases. Such interventions should especially focus on building self-efficacy to use condoms.  相似文献   
998.
INTRODUCTION: To plan for future acceptance and implementation of computer-related technology, it is necessary to understand orthodontists' current perceptions and attitudes toward emerging technologies. METHODS: An anonymous, self-administered, mail-out survey of Canadian orthodontists was conducted. The response rate was 45.6% (304/667). RESULTS: Most orthodontists indicated that computer technology could improve current practice efficiency and quality of patient care. Only 15% reported that digital models are quite or very useful; 73.6%, 69.1%, 55%, and 37.4% agreed or strongly agreed with using digital and electronic technology to consult with other dental specialists, other orthodontists, general dentists, and the public, respectively. Cost of the technology was reported as a significant or insurmountable obstacle by 54% of the respondents. Interprovincial legislation, unclear consultation remuneration guidelines, and lack of comfort with the technology were not perceived as significant obstacles. Only 36% reported security or privacy issues as a significant or insurmountable obstacle. CONCLUSIONS: Canadian orthodontists seem to view digital and electronic technology as useful and capable of improving their offices' efficiency and production. Although they are sensitive to some potential obstacles, they are willing to overcome these and incorporate the technology into their practices.  相似文献   
999.
D G Wilson  H Rees  M H Roberts 《Pain》1991,44(2):195-200
Four behavioural tests have been used to study the antinociceptive effects of electrical stimulation of the anterior pretectal nucleus (APtN) in the rat. The antinociceptive effects of stimulating this nucleus, which lies dorsally in the posterior diencephalon, have recently been studied extensively but always using briefly applied heat stimuli. It is reported here that APtN stimulation effectively inhibited responses to briefly applied noxious pressure and longer-lasting noxious chemical (formalin) stimuli. Although the tail-flick reflex to noxious heat was very potently depressed by APtN stimulation, responses to noxious heat in the hot-plate test were not. Three doses of morphine were also studied with each test and it was concluded that 15 sec of 35 microA r.m.s. current into the APtN was as effective as 3-5 mg/kg morphine s.c. in the rat.  相似文献   
1000.
Extra-erythrocyte hemoglobin (EEH) level and total peroxidase activity (TPA) have been analysed in the blood serum and plasma of 44 patients following hyperbaric oxygenation (HBO). The levels of the parameters tested decreased after 3 HBO procedures and remained low to the end of the treatment period in the first group of patients. In the second group of patients, on the contrary, EEH and TPA levels increased after 3 HBO procedures and remained high to the end of the treatment period. In both groups of patients EEH changes correlated with TPA alterations. Possible EEH and TPA determination for the estimation and enhancement of HBO treatment efficacy is discussed.  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