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   1057篇
  免费   64篇
  国内免费   46篇
耳鼻咽喉   2篇
儿科学   145篇
妇产科学   20篇
基础医学   74篇
口腔科学   69篇
临床医学   102篇
内科学   185篇
皮肤病学   11篇
神经病学   196篇
特种医学   140篇
外国民族医学   1篇
外科学   48篇
综合类   14篇
预防医学   28篇
眼科学   7篇
药学   71篇
  1篇
肿瘤学   53篇
  2023年   7篇
  2022年   8篇
  2021年   7篇
  2020年   12篇
  2019年   6篇
  2018年   17篇
  2017年   15篇
  2016年   16篇
  2015年   19篇
  2014年   30篇
  2013年   39篇
  2012年   37篇
  2011年   46篇
  2010年   32篇
  2009年   30篇
  2008年   37篇
  2007年   62篇
  2006年   42篇
  2005年   29篇
  2004年   30篇
  2003年   28篇
  2002年   25篇
  2001年   24篇
  2000年   31篇
  1999年   27篇
  1998年   54篇
  1997年   54篇
  1996年   62篇
  1995年   50篇
  1994年   32篇
  1993年   32篇
  1992年   9篇
  1991年   17篇
  1990年   11篇
  1989年   20篇
  1988年   27篇
  1987年   19篇
  1986年   14篇
  1985年   17篇
  1984年   11篇
  1983年   13篇
  1982年   10篇
  1981年   12篇
  1980年   11篇
  1979年   5篇
  1978年   5篇
  1977年   8篇
  1975年   5篇
  1972年   2篇
  1967年   4篇
排序方式: 共有1167条查询结果,搜索用时 15 毫秒
71.
Long-term outcome after intravenous thrombolysis of basilar artery occlusion   总被引:13,自引:0,他引:13  
Context  Basilar artery occlusion (BAO) is an infrequent disease with high morbidity and mortality. Intra-arterial thrombolysis is advocated for treatment but is limited to use at specialized centers. Objective  To evaluate outcomes for patients with BAO treated with intravenous thrombolytic therapy. Design, Setting, and Participants  During 1995 to 2003, 50 consecutive patients with angiographically proven BAO were treated according to an institutional therapy protocol based on intravenous thrombolysis with recombinant tissue plasminogen activator (alteplase). Patients were treated at an urban university teaching hospital receiving all patients with ischemic stroke who were considered for thrombolysis in a catchment area of 1.5 million inhabitants in Helsinki, Finland. Intervention  Intravenous administration of alteplase (0.9 mg/kg) during a 1-hour infusion. Main Outcome Measures  Basilar artery recanalization determined by magnetic resonance angiography and clinical outcomes at 3 months and at 1 year or longer determined by modified Rankin Scale and Barthel Index scores. Results  Recanalization was studied in 43 patients and verified in 26 (52%) of all patients. By 3 months, 20 patients (40%) had died while 11 had good outcomes (modified Rankin Scale score, 0-2); 12 (24%) reached independence in activities of daily living (Barthel Index score, 95-100), and 6 (16%) were severely disabled (Barthel Index score, 0-50). In the long term (median follow-up 2.8 years), 15 patients (30%) reached good outcomes (modified Rankin Scale score, 0-2) while 23 (46%) died. Conclusions  Intravenous administration of alteplase for patients with BAO appears to be associated with rates of survival, recanalization, and independent functional outcome comparable with those reported with endovascular approaches. These data suggest that a randomized trial is needed to compare these approaches for treatment of BAO.   相似文献   
72.
BACKGROUND: The CAPRIE study showed the superiority of clopidogrel over acetylsalicylic acid (ASA) for reducing the combined risk of major atherothrombotic events in patients with recent myocardial infarction (MI), recent ischaemic stroke (IS) or established peripheral arterial disease. The benefit of clopidogrel over ASA is amplified in high-risk patients. Proof of concept for the benefit of clopidogrel in addition to ASA in patients with coronary manifestations of atherothrombosis was provided by the CURE trial. METHODS: MATCH is a randomized, double-blind, placebo-controlled trial that compares clopidogrel and ASA versus clopidogrel alone in high-risk patients with recently symptomatic cerebrovascular disease. Eligible patients have experienced a transient ischaemic attack (TIA) or IS within the last 3 months and have evidence of at least 1 additional risk factor within the last 3 years (prior IS, MI, stable or unstable angina pectoris, diabetes or symptomatic peripheral arterial disease). Patients were randomized to receive ASA 75 mg once daily or placebo, with both groups receiving clopidogrel 75 mg once daily as part of standard therapy. The primary end point is the composite of IS, MI, vascular death and rehospitalization for an acute ischaemic event. The duration of treatment and follow-up is 18 months for each patient. RESULTS: Enrollment was completed in April 2002, with 7,599 patients randomized to receive the study medication. The mean age at randomization was 66 years, and the qualifying event was IS in 78.9% of patients and TIA in 21.1%. The baseline features of the study cohort indicate a population that is at a high risk for atherothrombotic recurrence. CONCLUSION: MATCH is a major ongoing trial that will provide important data on the benefit of clopidogrel and ASA compared with clopidogrel alone for reduction of vascular ischaemic events in patients with recent TIA or IS who are at high risk of atherothrombotic event recurrence.  相似文献   
73.
BACKGROUND: The changes in the activity of a number of plasma markers of coagulation and fibrinolysis have previously been studied in patients with ischemic stroke, with conflicting results. We aimed to find out the changes in the activities of a wide array of markers of the coagulation and the fibrinolytic system of mildly or moderately affected first-ever ischemic stroke patients. METHODS: In a prospective, longitudinal, case-control study, we studied plasma plasminogen activator inhibitor type-1 (PAI-1) activity, tissue-type plasminogen activator antigen (t-PA:Ag), d-dimer, prothrombin fragment 1+2 (F 1+2), and thrombin-antithrombin III complex (TAT) levels in 55 consecutive patients on admission, 1 week, 1 month, and 3 months after an ischemic stroke. Sex- and age-matched controls were studied once. All patients underwent blood sampling at each study time point; comprehensive stroke risk factors were recorded, and the etiology of the ischemic stroke was determined. All patients were contacted 3 years later for possible recurrent ischemic events. RESULTS: PAI-1 activity was increased in the acute phase and at 3 months, D-dimer levels were significantly higher at 1 week and 1 month after stroke, whereas t-PA:Ag, TAT and F 1+2 levels remained stable during the whole study period. CONCLUSIONS: The changes of the fibrinolytic and coagulation system activity in the patients with mild or moderate ischemic stroke appeared minor compared with the results of previous studies, which included more severely ill patients.  相似文献   
74.
BACKGROUND: The jaw (an unusual site of primary tumors in children and adolescents) has lesions often found incidentally by dentists on routine panoramic radiographs or during examination of a child who has swelling or tooth pain. OBJECTIVE: This pictorial seeks to familiarize pediatric radiologists with the radiographic appearance of a variety of primary jaw lesions. MATERIALS AND METHODS: We retrospectively searched institutional records for cases of primary jaw lesions in children and adolescents. Jaw lesions were characterized as: I, well-circumscribed radiolucent lesions; II, lesions with mixed or variable appearance; III, poorly circumscribed radiolucent lesions; and IV, radiopaque lesions. RESULTS: Although most oral and maxillofacial lesions in children are benign, a broad spectrum of tumors was identified; lesions may occur in patients with unrelated prior malignancy. CONCLUSION: Because radiologic studies may identify jaw lesions and direct further care, familiarity with the appearance of these entities is prudent.  相似文献   
75.
Generalized anxiety disorders three to four months after ischemic stroke   总被引:1,自引:0,他引:1  
BACKGROUND AND OBJECTIVE: The main objective of our study was to detail the frequency and clinical determinants of poststroke generalized anxiety disorders in a large, well-defined stroke cohort. METHODS: A total of 277 stroke patients aged 55-85 were subjected to a comprehensive psychiatric evaluation between 3 and 4 months after ischemic stroke. Primary generalized anxiety disorder or generalized anxiety disorder due to stroke were diagnosed according to DSM-IV symptom criteria. RESULTS: The frequency of any generalized anxiety disorder was 20.6% (n = 57). According to a logistic model, any generalized anxiety disorder was associated with a history of epilepsy, comorbid depressive disorder, severity of depression, severity of anxiety, and the use of anxiolytic drugs. A discriminant analysis identified four factors that distinguished the two diagnostic subgroups from one another: the level of psychosocial functioning (worse score in patients with generalized anxiety due to stroke), a history of migraine, anterior circulation stroke localization (more frequent in patients with generalized anxiety disorder due to stroke), and a history of insomnia (more frequent in patients with primary generalized anxiety disorder). CONCLUSIONS: Clinically significant anxiety is common in ischemic stroke patients and may hamper their rehabilitation.  相似文献   
76.
Understanding diet and energy balance as risk factors for breast, colon, and other cancers requires information on the contribution of each factor and of interactions among factors to cancer risk. Rodent models for breast cancer provide extensive data on effects of dietary fat and calories, energy balance, body weight gain, and physical activity on tumor development. Analyses of the combined data from many studies have shown clearly that quality and quantity of dietary fat and energy balance contribute independently to increased mammary gland tumorigenesis. These findings were seen in female rats fed diets high in fat (35-40% of calories) compared to rats fed control diets, with approximately 10% of calories as fat (Fay and Freedman, 1997, Breast Cancer Res. Treat. 46, 215-223). The methods used permit comparison of experimental and epidemiological data, and they may be useful in extrapolating between species and developing public health recommendations. In addition to the contributions of lifetime-diet composition, intake, energy balance, and physical activity to cancer risk, there are questions about the timing and duration of alterations in these factors and about the "dose-response" characteristics of cancer risk to the factors. Endocrine mechanisms may be significant in mammary gland tumor risk, but experimental and epidemiological data indicate that cancers at other sites, such as colon and liver, also are influenced by the factors listed. Other diet and lifestyle factors that influence energy, or specifically fat, metabolism may also affect risk for cancers that are promoted by increased intake of fat and calories. Studies of separate and interactive effects of dietary fat, black tea, weight gain, and mammary gland tumorigenesis (Rogers, et al, 1998, Carcinogenesis 19, 1269-1273) have been analyzed. Using adjustment of carcinogenesis endpoints for body weight, tumor burden, and latency, they were found to be related to weight gain within treatment groups in 2 of 3 experiments.   相似文献   
77.
BB-10010 is a genetically engineered variant of human macrophage inflammatory protein-1 alpha with improved solution properties. We show here that it mobilizes stem cells into the peripheral blood. We investigated the mobilizing effects of BB-10010 on the numbers of circulating 8-day spleen colony-forming units (CFU-S8), CFU-S12, and progenitors with marrow repopulating ability (MRA). A single subcutaneous dose of BB-10010 caused a twofold increase in circulating numbers of CFU-S8, CFU-S12, and MRA 30 minutes after dosing. We also investigated the effects of granulocyte colony-stimulating factor (G- CSF) and the combination of G-CSF with BB-10010 on progenitor mobilization. Two days of G-CSF treatment increased circulating CFU-S8, CFU-S12, and MRA progenitors by 25.7-, 19.8-, and 27.7-fold. A single administration of BB-10010 after 2 days of G-CSF treatment increased circulating CFU-S8, CFU-S12, and MRA even further to 38-, 33-, and 100- fold. Splenectomy resulted in increased circulating progenitor numbers but did not change the pattern of mobilization. Two days of treatment with G-CSF then increased circulating CFU-S8, CFU-S12, and MRA by 64-, 69-, and 32-fold. A single BB-10010 administration after G-CSF treatment further increased them to 85-, 117-, and 140-fold, respectively, compared with control. We conclude that BB-10010 causes a rapid increase in the number of circulating hematopoietic progenitors and further enhances the numbers induced by pretreatment with G-CSF. BB- 10010 preferentially mobilized the more primitive progenitors with marrow repopulating activity, releasing four times the number achieved with G-CSF alone. Translated into a clinical setting, this improvement in progenitor cell mobilization may enhance the efficiency of harvest and the quality of grafts for peripheral blood stem cell transplantation.  相似文献   
78.
Tumor cells from eight adult patients with T-cell chronic malignancies were investigated with a series of monoclonal antibodies recognizing T- cell differentiation antigens. This series allowed definition of discrete subpopulations of mature T cells with functional specialization. All six patients with Sezary syndrome and one patient with T-chronic lymphocytic leukemia had cells with the same phenotype as normal helper/inducer T cells, whereas the other patient with T- chronic lymphocytic leukemia had cell with the same phenotype as normal cytotoxic/suppressor T cells. Some clinical manifestations observed in these patients may reflect retention of functional activities by their malignant cells.  相似文献   
79.

Background

Postal questionnaires are an economical and simple method of data collection for research purposes but are subject to non-response bias. Several studies have explored the effect of monetary and non-monetary incentives on response. Recent meta-analyses conclude that financial incentives are an effective way of increasing response rates. However, large surveys rarely have the resources to reward individual participants. Three previous papers report on the effectiveness of lottery incentives with contradictory results. This study aimed to determine the effect of including a lottery-style incentive on response rates to a postal health survey.

Methods

Randomised controlled trial. Setting: North and West Birmingham. 8,645 patients aged 18 or over randomly selected from registers of eight general practices (family physician practices). Intervention: Inclusion of a flyer and letter with a health questionnaire informing patients that returned questionnaires would be entered into a lottery-style draw for £100 of gift vouchers. Control: Health questionnaire accompanied only by standard letter of explanation. Main outcome measures: Response rate and completion rate to questionnaire.

Results

5,209 individuals responded with identical rates in both groups (62.1%). Practice, patient age, sex and Townsend score (a postcode based deprivation measure) were identified as predictive of response, with higher response related to older age, being female and living in an area with a lower Townsend score (less deprived).

Conclusion

This RCT, using a large community based sample, found that the offer of entry into a lottery style draw for £100 of High Street vouchers has no effect on response rates to a postal health questionnaire.  相似文献   
80.
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