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   13906篇
  免费   1084篇
  国内免费   35篇
耳鼻咽喉   105篇
儿科学   331篇
妇产科学   354篇
基础医学   1755篇
口腔科学   324篇
临床医学   1474篇
内科学   3085篇
皮肤病学   234篇
神经病学   1361篇
特种医学   552篇
外科学   2041篇
综合类   291篇
一般理论   11篇
预防医学   1019篇
眼科学   301篇
药学   906篇
中国医学   9篇
肿瘤学   872篇
  2023年   61篇
  2021年   216篇
  2020年   136篇
  2019年   205篇
  2018年   282篇
  2017年   176篇
  2016年   189篇
  2015年   220篇
  2014年   358篇
  2013年   742篇
  2012年   835篇
  2011年   957篇
  2010年   505篇
  2009年   455篇
  2008年   858篇
  2007年   924篇
  2006年   930篇
  2005年   905篇
  2004年   796篇
  2003年   791篇
  2002年   773篇
  2001年   168篇
  2000年   152篇
  1999年   163篇
  1998年   162篇
  1997年   113篇
  1996年   116篇
  1995年   129篇
  1994年   114篇
  1993年   116篇
  1992年   148篇
  1991年   124篇
  1990年   95篇
  1989年   113篇
  1988年   123篇
  1987年   101篇
  1986年   117篇
  1985年   136篇
  1984年   160篇
  1983年   134篇
  1982年   130篇
  1981年   114篇
  1980年   121篇
  1979年   64篇
  1978年   66篇
  1977年   65篇
  1976年   73篇
  1974年   64篇
  1973年   48篇
  1972年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Gestational trophoblastic neoplasia (GTN) patients are treated according to the eight-variable International Federation of Gynaecology and Obstetrics (FIGO) scoring system, that aims to predict first-line single-agent chemotherapy resistance. FIGO is imperfect with one-third of low-risk patients developing disease resistance to first-line single-agent chemotherapy. We aimed to generate simplified models that improve upon FIGO. Logistic regression (LR) and multilayer perceptron (MLP) modelling (n = 4191) generated six models (M1-6). M1, all eight FIGO variables (scored data); M2, all eight FIGO variables (scored and raw data); M3, nonimaging variables (scored data); M4, nonimaging variables (scored and raw data); M5, imaging variables (scored data); and M6, pretreatment hCG (raw data) + imaging variables (scored data). Performance was compared to FIGO using true and false positive rates, positive and negative predictive values, diagnostic odds ratio, receiver operating characteristic (ROC) curves, Bland-Altman calibration plots, decision curve analysis and contingency tables. M1-6 were calibrated and outperformed FIGO on true positive rate and positive predictive value. Using LR and MLP, M1, M2 and M4 generated small improvements to the ROC curve and decision curve analysis. M3, M5 and M6 matched FIGO or performed less well. Compared to FIGO, most (excluding LR M4 and MLP M5) had significant discordance in patient classification (McNemar's test P < .05); 55-112 undertreated, 46-206 overtreated. Statistical modelling yielded only small gains over FIGO performance, arising through recategorisation of treatment-resistant patients, with a significant proportion of under/overtreatment as the available data have been used a priori to allocate primary chemotherapy. Streamlining FIGO should now be the focus.  相似文献   
2.
3.
4.
5.
Iron deficiency anemia is often listed among potential adverse effects of gastric acid-suppressive medications, given that gastric acidity promotes intestinal absorption of nonheme iron. Additionally, the antacid calcium carbonate can inhibit iron absorption. However, there is little direct clinical evidence that proton-pump inhibitors, histamine-2 receptor antagonists, or calcium carbonate cause iron deficiency anemia. Most case reports have had substantial limitations (e.g., minimal follow-up and presence of other causes of iron deficiency), and retrospective cohort studies have lacked sufficient patient-specific detail to make strong causal inferences. We present 2 cases—both with detailed, prospective 10-year follow-up—in which combinations of proton-pump inhibitors, histamine-2 receptor antagonists and calcium carbonate were clearly associated with development of iron deficiency anemia. Overt iron-deficiency anemia is probably uncommon in patients who use acid-modifying medications and who have no other conditions that predispose to iron deficiency. Nevertheless, clinicians should be aware of this potential complication, given widespread use of these agents.  相似文献   
6.
Kawasaki disease (KD) is a systemic vasculitis frequent in children younger than 5 years of age. It involves coronary arteries and other medium-sized vessels. There also exists evidence of inflammatory and proliferative changes affecting the biliary tract and lymphocyte infiltration of the renal interstitial. We describe the case of a 9-year-old girl who developed high-grade fever, bilateral non-purulent conjunctivitis, «strawberry» tongue, desquamation of the fingers and toes, cholestatic syndrome, edema and elevated serum creatinine. KD is a diagnostic challenge for the pediatrician. In every patient with high-grade fever, cholestasis and acute kidney injury, KD should be included in the differential diagnosis, even though more research is necessary to evaluate this atypical association.  相似文献   
7.
8.
The purpose of this work was to develop a quantitative method for evaluating the pulmonary inflammatory process (PIP) through the computational analysis of chest radiography exams in posteroanterior (PA) and lateral views. The quantification procedure was applied to patients with tuberculosis (TB) as the motivating application.A study of high-resolution computed tomography (HRCT) examinations of patients with TB was developed to establish a relation between the inflammatory process and the signal difference-to-noise ratio (SDNR) measured in the PA projection. A phantom essay was used to validate this relation, which was implemented using an algorithm that is able to estimate the volume of the inflammatory region based solely on SDNR values in the chest radiographs of patients.The PIP volumes that were quantified for 30 patients with TB were used for comparisons with direct HRCT analysis for the same patient. The Bland–Altman statistical analyses showed no significant differences between the 2 quantification methods. The linear regression line had a correlation coefficient of R2 = 0.97 and P < 0.001, showing a strong association between the volume that was determined by our evaluation method and the results obtained by direct HRCT scan analysis.Since the diagnosis and follow-up of patients with TB is commonly performed using X-rays exams, the method developed herein can be considered an adequate tool for quantifying the PIP with a lower patient radiation dose and lower institutional cost. Although we used patients with TB for the application of the method, this method may be used for other pulmonary diseases characterized by a PIP.  相似文献   
9.

Background

Physicians treating nonvalvular atrial fibrillation (AF) assess stroke and bleeding risks when deciding on anticoagulation. The agreement between empirical and physician-estimated risks is unclear. Furthermore, the association between patient and physician sex and anticoagulation decision-making is uncertain.

Methods

We pooled data from 2 national primary care physician chart audit databases of patients with AF (Facilitating Review and Education to Optimize Stroke Prevention in Atrial Fibrillation and Coordinated National Network to Engage Physicians in the Care and Treatment of Patients with Atrial Fibrillation Chart Audit) with a combined 1035 physicians (133 female, 902 male) and 10,927 patients (4567 female and 6360 male).

Results

Male physicians underestimated stroke risk in female patients and overestimated risk in male patients. Female physicians estimated stroke risk well in female patients but underestimated the risk in male patients. Risk of bleeding was underestimated in all. Despite differences in risk assessment by physician and patient sex, > 90% of patients received anticoagulation across all subgroups. There was modest agreement between physician estimated and calculated (ie, CHADS2 score) stroke risk: Kappa scores were 0.41 (0.35-0.47) for female physicians and 0.34 (0.32-0.36) for male physicians.

Conclusions

Our study is the first to examine the association between patient and physician sex influences and stroke and bleeding risk estimation in AF. Although there were differences in agreement between physician estimated stroke risk and calculated CHADS2 scores, these differences were small and unlikely to affect clinical practice; further, despite any perceived differences in the accuracy of risk assessment by sex, most patients received anticoagulation.  相似文献   
10.

Background

Anticoagulant and antiplatelet agents (ACAP) have been shown to negatively affect trauma patients.

Methods

Outcomes in adults with rib fractures were reviewed. Pearson chi-square test was used for analysis. Multivariate logistic regression was used to adjust for potential confounders.

Results

Of the 1448 included patients, 149 (10.3%) took preinjury ACAP; these patients were significantly older than non-anticoagulated patients (72 vs. 54 years, P?≤?0.05). There was no difference in pulmonary complications, ICU admissions or ICU LOS. The preinjury ACAP group had a significantly longer LOS (12.03 vs. 9.33 days, P?=?0.004), fewer pulmonary contusions (15.43% vs. 22.94%, P?=?0.037), and fewer thoracic drainage procedures (10.74% vs. 18.17%, P = 0.023). Multivariate adjustment for possible confounders revealed that patients taking warfarin had a significantly longer LOS (+7.38 days). After adjustment there was no difference in mortality.

Conclusion

Preinjury ACAP use does not increase mortality or morbidity in patients with rib fractures.

Summary

We demonstrated that preinjury anticoagulation and antiplatelet agents do not increase mortality or morbidity in patients with rib fractures. However, they lead to a longer hospital length of stay, particularly in patients on warfarin.  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