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   105665篇
  免费   12778篇
  国内免费   507篇
耳鼻咽喉   556篇
儿科学   1301篇
妇产科学   967篇
基础医学   3966篇
口腔科学   1357篇
临床医学   11969篇
内科学   7749篇
皮肤病学   1126篇
神经病学   3218篇
特种医学   2067篇
外国民族医学   3篇
外科学   5635篇
综合类   25752篇
一般理论   25篇
预防医学   8827篇
眼科学   571篇
药学   14694篇
  388篇
中国医学   25601篇
肿瘤学   3178篇
  2024年   70篇
  2023年   2234篇
  2022年   3804篇
  2021年   5159篇
  2020年   5549篇
  2019年   3685篇
  2018年   3182篇
  2017年   4450篇
  2016年   4559篇
  2015年   4355篇
  2014年   11421篇
  2013年   9600篇
  2012年   9654篇
  2011年   9420篇
  2010年   7338篇
  2009年   5383篇
  2008年   4609篇
  2007年   4559篇
  2006年   3607篇
  2005年   2823篇
  2004年   2182篇
  2003年   1796篇
  2002年   1368篇
  2001年   1228篇
  2000年   1041篇
  1999年   791篇
  1998年   582篇
  1997年   489篇
  1996年   352篇
  1995年   342篇
  1994年   314篇
  1993年   229篇
  1992年   181篇
  1991年   178篇
  1990年   134篇
  1989年   128篇
  1988年   102篇
  1987年   107篇
  1986年   94篇
  1985年   190篇
  1984年   261篇
  1983年   210篇
  1982年   226篇
  1981年   204篇
  1980年   174篇
  1979年   157篇
  1978年   108篇
  1977年   74篇
  1976年   79篇
  1975年   72篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Books received     
The new discipline of Global Security Studies is defined as the consideration of transnational issues with global implications that can only be solved by collaborative endeavour. There is a need for new thinking leading to actions for a sustainable future. An analogy is drawn with the preventive activities of public health medicine, and the opportunities presented to Medical Action for Global Security are examined.  相似文献   
5.
Objective: To examine and compare the prospective effect of the common mental disorders (CMD) anxiety and depression on duration and recurrence of sickness absence (SA), and to investigate whether the effect of CMD on SA is detectable over time. Method: Information from a large epidemiological health study (N = 13 436) was linked with official records of SA episodes lasting ≥16 days up to 6 years after participation. Common mental disorders were assessed with the Hospital Anxiety and Depression Scale (HADS). Associations were analysed with Cox regression and multinomial logistic regression models controlling for potential covariates. Results: Comorbid anxiety and depression, and anxiety only were significant risk factors for SA after adjusting for covariates, whilst depression only was not. Anxiety and depression were stronger predictors for longer duration of SA episodes compared with shorter duration and associated with more frequent recurrence of SA. There was a general trend toward the effect of CMD on SA becoming weaker over time; however, the effect of anxiety only on SA remained stable throughout the follow‐up. Conclusion: Common mental disorders are long‐lasting predictors of onset, duration and recurrence of SA. Anxiety appears to be a more important contributor to long‐term SA than previously described in the literature.  相似文献   
6.
PurposeTo examine the risk of femoral access site complications in patients undergoing carotid stent placement who were treated with a closure device compared with patients who were not treated with a closure device.Materials and MethodsA national, multihospital patient database, the Premier Perspective database, was used to identify patients hospitalized for carotid stent placement from 2006–2011. To reduce potential selection bias, a propensity score was generated for each patient using relevant clinical variables. Propensity score adjustment via 1:1 matching was performed on patients who did and did not receive a closure device. Primary outcomes were minor femoral access site complications and major complications requiring procedural intervention. Secondary outcomes included in-hospital mortality, stroke, and blood transfusion.ResultsAmong 12,287 patients who underwent carotid stent placement at 217 hospitals, 6,398 (52%) received a closure device on the day of the procedure. After propensity score matching, patients who received a closure device had a lower likelihood of minor access site complications (4.2% vs 5.4%; odds ratio = 0.77; 95% confidence interval, 0.55–0.93; P = .0071) compared with patients who did not receive a closure device; however, this difference was small and likely not clinically relevant. Both groups had a similar risk of major access site complications (P = .32), in-hospital mortality (P = .0520), and stroke (P = .31).ConclusionsUse of a closure device was not associated with a substantially reduced risk of major adverse events after carotid stent placement and was associated with only a small improvement in minor access site complications.  相似文献   
7.
BackgroundLiterature suggests that sex steroid hormones may modify the risk for Parkinson's disease (PD). We investigated the potential effect of reproductive factors on the clinical features of idiopathic PD (IPD) patients.MethodsAll IPD female patients admitted to and evaluated at our Institute over a 12-month period were included in the present cross-sectional study. We investigated the effect of the following parameters by multivariate linear regression analysis: age at menarche, age at menopause, length of fertile life, duration of exposure to endogenous estrogens and cumulative length of pregnancies, use of contraceptives and hormonal replacement therapy.ResultsIn total, 579 patients were evaluated and 497 reported menopause before PD onset. In this population, age at PD onset was positively associated with age at menarche and at menopause, length of fertile life and duration of estrogen exposure. Moreover, UPDRS motor score was inversely associated with age at menopause, length of fertile life and duration of estrogen exposure. Increasing age at menarche was also associated with predominant resting tremor at PD onset. In models refitted on patients with early PD (disease duration <5 years; N = 226) all the associations found were confirmed. The relationship between surrogates of estrogen exposure and UPDRS motor score actually became more significant.ConclusionsOur observations support the concept that hormonal exposure of the nigro-striatal network during life may influence its susceptibility to degenerative stimuli in later life, but the association does not seem to be unique? unidirectional. In particular, increased severity of PD signs correlates with shorter duration of estrogen exposure. The underlying mechanisms need to be clarified.  相似文献   
8.
9.

Objective

The problem of identifying, in advance, the most effective treatment agent for various psychiatric conditions remains an elusive goal. To address this challenge, we investigate the performance of the proposed machine learning (ML) methodology (based on the pre-treatment electroencephalogram (EEG)) for prediction of response to treatment with a selective serotonin reuptake inhibitor (SSRI) medication in subjects suffering from major depressive disorder (MDD).

Methods

A relatively small number of most discriminating features are selected from a large group of candidate features extracted from the subject’s pre-treatment EEG, using a machine learning procedure for feature selection. The selected features are fed into a classifier, which was realized as a mixture of factor analysis (MFA) model, whose output is the predicted response in the form of a likelihood value. This likelihood indicates the extent to which the subject belongs to the responder vs. non-responder classes. The overall method was evaluated using a “leave-n-out” randomized permutation cross-validation procedure.

Results

A list of discriminating EEG biomarkers (features) was found. The specificity of the proposed method is 80.9% while sensitivity is 94.9%, for an overall prediction accuracy of 87.9%. There is a 98.76% confidence that the estimated prediction rate is within the interval [75%, 100%].

Conclusions

These results indicate that the proposed ML method holds considerable promise in predicting the efficacy of SSRI antidepressant therapy for MDD, based on a simple and cost-effective pre-treatment EEG.

Significance

The proposed approach offers the potential to improve the treatment of major depression and to reduce health care costs.  相似文献   
10.
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