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   71600篇
  免费   4073篇
  国内免费   1848篇
耳鼻咽喉   765篇
儿科学   1651篇
妇产科学   1031篇
基础医学   7534篇
口腔科学   894篇
临床医学   8507篇
内科学   10217篇
皮肤病学   1998篇
神经病学   3740篇
特种医学   1900篇
外国民族医学   1篇
外科学   4693篇
综合类   11309篇
现状与发展   3篇
预防医学   7807篇
眼科学   605篇
药学   9352篇
  81篇
中国医学   3987篇
肿瘤学   1446篇
  2024年   117篇
  2023年   802篇
  2022年   1729篇
  2021年   2505篇
  2020年   2215篇
  2019年   1799篇
  2018年   1887篇
  2017年   1954篇
  2016年   2050篇
  2015年   2162篇
  2014年   4436篇
  2013年   4843篇
  2012年   4375篇
  2011年   4640篇
  2010年   3691篇
  2009年   3482篇
  2008年   3447篇
  2007年   3481篇
  2006年   3084篇
  2005年   2734篇
  2004年   2283篇
  2003年   2010篇
  2002年   1667篇
  2001年   1529篇
  2000年   1411篇
  1999年   1246篇
  1998年   1008篇
  1997年   1015篇
  1996年   877篇
  1995年   873篇
  1994年   791篇
  1993年   677篇
  1992年   675篇
  1991年   604篇
  1990年   519篇
  1989年   494篇
  1988年   505篇
  1987年   467篇
  1986年   372篇
  1985年   417篇
  1984年   394篇
  1983年   277篇
  1982年   329篇
  1981年   269篇
  1980年   246篇
  1979年   192篇
  1978年   177篇
  1977年   153篇
  1976年   113篇
  1973年   101篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.

Background

The optimal noninvasive test (NIT) for patients with diabetes and stable symptoms of coronary artery disease (CAD) is unknown.

Objectives

The purpose of this study was to assess whether a diagnostic strategy based on coronary computed tomographic angiography (CTA) is superior to functional stress testing in reducing adverse cardiovascular (CV) outcomes (CV death or myocardial infarction [MI]) among symptomatic patients with diabetes.

Methods

PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) was a randomized trial evaluating an initial strategy of CTA versus functional testing in stable outpatients with symptoms suggestive of CAD. The study compared CV outcomes in patients with diabetes (n = 1,908 [21%]) and without diabetes (n = 7,058 [79%]) based on their randomization to CTA or functional testing.

Results

Patients with diabetes (vs. without) were similar in age (median 61 years vs. 60 years) and sex (female 54% vs. 52%) but had a greater burden of CV comorbidities. Patients with diabetes who underwent CTA had a lower risk of CV death/MI compared with functional stress testing (CTA: 1.1% [10 of 936] vs. stress testing: 2.6% [25 of 972]; adjusted hazard ratio: 0.38; 95% confidence interval: 0.18 to 0.79; p = 0.01). There was no significant difference in nondiabetic patients (CTA: 1.4% [50 of 3,564] vs. stress testing: 1.3% [45 of 3,494]; adjusted hazard ratio: 1.03; 95% confidence interval: 0.69 to 1.54; p = 0.887; interaction term for diabetes p value = 0.02).

Conclusions

In diabetic patients presenting with stable chest pain, a CTA strategy resulted in fewer adverse CV outcomes than a functional testing strategy. CTA may be considered as the initial diagnostic strategy in this subgroup. (PROspective Multicenter Imaging Study for Evaluation of Chest Pain [PROMISE]; NCT01174550)  相似文献   
2.
In this review we summarize the impact of the various modalities of breast cancer therapy coupled with intrinsic patient factors on incidence of subsequent treatment-induced myelodysplasia and acute myelogenous leukemia (t-MDS/AML). It is clear that risk is increased for patients treated with radiation and chemotherapy at younger ages. Radiation is associated with modest risk, whereas chemotherapy, particularly the combination of an alkylating agent and an anthracycline, carries higher risk and radiation and chemotherapy combined increase the risk markedly. Recently, treatment with granulocyte colony-stimulating factor (G-CSF), but not pegylated G-CSF, has been identified as a factor associated with increased t-MDS/AML risk. Two newly identified associations may link homologous DNA repair gene deficiency and poly (ADP-ribose) polymerase inhibitor treatment to increased t-MDS/AML risk. When predisposing factors, such as young age, are combined with an increasing number of potentially leukemogenic treatments that may not confer large risk singly, the risk of t-MDS/AML appears to increase. Patient and treatment factors combine to form a biological cascade that can trigger a myelodysplastic event. Patients with breast cancer are often exposed to many of these risk factors in the course of their treatment, and triple-negative patients, who are often younger and/or BRCA positive, are often exposed to all of them. It is important going forward to identify effective therapies without these adverse associated effects and choose existing therapies that minimize the risk of t-MDS/AML without sacrificing therapeutic gain.

Implications for Practice

Breast cancer is far more curable than in the past but requires multimodality treatment. Great care must be taken to use the least leukemogenic treatment programs that do not sacrifice efficacy. Elimination of radiation and anthracycline/alkylating agent regimens will be helpful where possible, particularly in younger patients and possibly those with homologous repair deficiency (HRD). Use of colony-stimulating factors should be limited to those who truly require them for safe chemotherapy administration. Further study of a possible leukemogenic association with HRD and the various forms of colony-stimulating factors is badly needed.
  相似文献   
3.
4.
ABSTRACT

Purpose

New instrument-based techniques for anterior chamber (AC) cell counting can offer automation and objectivity above clinician assessment. This review aims to identify such instruments and its correlation with clinician estimates.  相似文献   
5.
猕猴桃汁抗环磷酰胺致突变作用的机理   总被引:12,自引:1,他引:11  
目的用大鼠外周血双核淋巴细胞微核测试法(CBMNT),在哺乳动物整体水平,研究猕猴桃汁抗环磷酰胺(CP)的致突变作用以及生物转化Ⅱ相酶的作用。方法测定大鼠外周血双核淋巴细胞微核细胞率及肝组织中总谷胱甘肽硫转移酶(GST)、尿苷二磷酸葡萄糖醛酸转移酶(UDPGT)、谷氨酰胺转肽酶(γGT)活性。结果猕猴桃汁对CP诱发的大鼠外周血双核淋巴细胞微核细胞率有显著抑制作用,能明显诱导大鼠肝脏总GST、UDGTP活性,但对γGT活性无显著影响。大鼠外周血双核淋巴细胞微核细胞率与总GST、UDGTP活性呈明显负相关。结论猕猴桃汁抗CP致微核形成作用的机理可能是通过诱导机体外来化合物代谢解毒酶系,加速CP的代谢灭活  相似文献   
6.
Dantrolene seems to be the causal therapy in malignant hyperthermia (MH) crisis but the complex mechanisms of MH and dantrolene therapy are still not fully understood. The influence of dantrolene on ryanodine-induced contractures has been reported in animal studies only. In the present study 20 patients from] 7 families were tested for MH using the protocol of the European Malignant Hyperthermia Group. In addition ryanodine-induced contractures were evaluated following bolus application of 10.0 μmol · 1-1 ryanodine. After pretreatment with 1 μimol · 1-1 dantrolene ryanodine-provoked contractures developed significantly later in MHS (15.8±1.8 min) and MHN (46.0±4.2 min) muscle specimens than after ryanodine alone (MHS 4.8±0.7 min), (MHN 13.7±0.9 min). They were no longer observed in either group after pretreatment with 5 μimol · 1-1 dantrolene. We conclude that dantrolene is able to attenuate ryanodine-induced contractures dose-dependendy, and therefore it is speculated that dantrolene could specifically act at the ryanodine receptor binding site.  相似文献   
7.
8.
9.
汤先镗  王文铨 《农垦医学》1989,11(3):141-146
在新疆石河子市远郊缺碘地甲病区7~17岁儿童中取样,检测智力、精神运动功能、身高、体重和骨龄,发现精神运动发育障碍和骨龄落后的程度及发生频度明显高于非病区;而智力落后和体格发育落后两区无显著差异。根据这一发现认为在“亚地克病”诊断中,“精神运动发育测验”较“比内测验”更具有特异性和敏感性;建议在“出生、居住于缺碘地甲病区”前提下,将精神运动发育障碍和智力落后并列为主要条件。另根据地克病的分型原则,提出“亚地克病”的分型标准。  相似文献   
10.
BACKGROUND: In allergic conditions, the degree of skin test reactivity does not always correlate with the severity of clinical symptoms. Additional factors may contribute to the reported symptom severity. OBJECTIVES: To investigate the association between the magnitude of the skin prick test (SPT) response and the reported symptom severity in patients with allergic rhinitis and the possible modifying role of psychological factors. METHODS: One hundred four patients with allergic rhinitis and 23 with non-allergic rhinitis, classified according to their SPT response to 19 aeroallergens, were asked to rate the severity of five symptoms and to indicate whether their symptoms intensified on exposure to five common aeroallergens. They also completed a psychological questionnaire. Results Reported symptom severity of allergic rhinitis did not correlate with weal size for any of the aeroallergens tested or with the number of positive responses on SPT. It was not related to patient age, sex, or education. The reported symptoms severity correlated positively (0.29, P < 0.01) with reported symptom intensification on exposure to allergens. Moreover, both outcomes were positively associated with the psychological factors of hypochondriasis (0.20, P < 0.05 and 0.18, P < 0.05, respectively), and somatic awareness (0.24, P < 0.05 and 0.33, P < 0.01, respectively), but not with neuroticism. CONCLUSIONS: The severity of symptoms experienced by patients with allergic rhinitis is apparently not related to the magnitude of SPT response, but rather to psychological factors of hypochondriasis and somatic awareness. Physicians should be aware of the contribution of psychological factors to patient perceptions of the intensity of symptoms and of the intensification of symptoms on their exposure to allergens.  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