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   1696篇
  免费   121篇
  国内免费   19篇
耳鼻咽喉   13篇
儿科学   41篇
妇产科学   57篇
基础医学   291篇
口腔科学   29篇
临床医学   120篇
内科学   306篇
皮肤病学   52篇
神经病学   238篇
特种医学   38篇
外科学   153篇
综合类   24篇
一般理论   2篇
预防医学   197篇
眼科学   36篇
药学   100篇
中国医学   21篇
肿瘤学   118篇
  2023年   5篇
  2022年   29篇
  2021年   64篇
  2020年   45篇
  2019年   69篇
  2018年   63篇
  2017年   57篇
  2016年   50篇
  2015年   74篇
  2014年   88篇
  2013年   108篇
  2012年   148篇
  2011年   149篇
  2010年   70篇
  2009年   71篇
  2008年   122篇
  2007年   118篇
  2006年   113篇
  2005年   107篇
  2004年   90篇
  2003年   60篇
  2002年   58篇
  2001年   8篇
  2000年   5篇
  1999年   6篇
  1998年   12篇
  1997年   14篇
  1996年   4篇
  1995年   8篇
  1994年   5篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   3篇
  1988年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1973年   2篇
  1968年   1篇
  1905年   1篇
排序方式: 共有1836条查询结果,搜索用时 250 毫秒
61.
A series of 2-(arylmethylthio)-3-phenylquinazolin-4-one derivatives have been synthesized and their antiplatelet aggregation activities were assessed against ADP and arachidonic acid-induced platelet aggregation in human plasma. Among the tested thioethers, derivative 2, 3, 5 and 16 were the most potent compounds with satisfactory IC50 for inhibition of platelet aggregation induced by ADP. Analysis of global physicochemical parameters shows some correlations between activities and molecular volume and also surface area of the studied derivatives.  相似文献   
62.
63.

Objective

To analyze disease‐free survival in patients with antineutrophil cytoplasmic antibody (ANCA)–associated small‐vessel vasculitis (AAV) treated with cyclophosphamide only or switched to azathioprine after 3 months of full remission while taking cyclophosphamide.

Methods

We analyzed disease‐free survival in all consecutive patients diagnosed with AAV between 1990 and 2000 at our center. Patients were treated with cyclophosphamide only (1990–1996) or switched to azathioprine after 3 months of remission while taking cyclophosphamide (1997–2000). All patients received at least 12 months of followup.

Results

Of the total 128 patients, 53 (41%) relapsed. Forty‐four of the 128 patients (34%) had been switched to azathioprine therapy. Disease‐free survival at 2 and 4 years was 76% and 65% in the cyclophosphamide group compared with 76% and 51% in the azathioprine group. In patients with proteinase 3 (PR3) classic ANCA (C‐ANCA)–associated vasculitis who were switched to azathioprine (n = 33), a positive C‐ANCA titer at the moment of treatment switch (n = 13) was significantly associated with relapse (RR 2.6, 95% confidence interval 1.1–8.0; P = 0.04). In patients with a negative ANCA titer at the time of switch to azathioprine, disease‐free survival at 2 and 4 years was 80% and 62%, which was identical to that for patients treated with cyclophosphamide only. In patients who were ANCA‐positive at the time of treatment switch, disease‐free survival at 2 and 4 years was only 58% and 17%.

Conclusion

Switching cyclophosphamide to azathioprine after induction of remission in patients with PR3‐ANCA‐associated vasculitis who are still ANCA‐positive at the time of treatment switch is associated with a high risk of relapse.
  相似文献   
64.
65.
Vascular abnormalities and glycogen accumulation in vascular smooth muscle fibres have been described in Pompe disease. Using carotid-femoral pulse wave velocity (cfPWV), the gold standard methodology for determining aortic stiffness, we studied whether aortic stiffness is increased in patients with Pompe disease. Eighty-four adult Pompe patients and 179 age- and gender-matched volunteers participated in this cross-sectional case-controlled study. Intima media thickness and the distensibility of the right common carotid artery were measured using a Duplex scanner. Aortic augmentation index, central pulse pressure, aortic reflexion time and cfPWV were assessed using the SphygmoCor® system. CfPWV was higher in patients than in volunteers (8.8 versus 7.4 m/s, p?<?0.001). This difference was still present after adjustment for age, gender, mean arterial blood pressure (MAP), heart rate and diabetes mellitus (p?=?0.001), and was shown by subgroup analysis to apply to the 40-59 years age group (p?=?0.004) and 60+ years age group (p?=?0.01), but not to younger age groups (p?=?0.99). Except for a shorter aortic reflexion time (p?=?0.02), indirect indicators of arterial stiffness did not differ between patients and volunteers. Relative to volunteers (20 %), more Pompe patients had a history of hypertension (36 %, p?=?0.005), and the MAP was higher than in volunteers (100 versus 92 mmHg, p?<?0.001). This study shows that patients with non-classic Pompe disease have increased aortic stiffness and blood pressure. Whether this is due to glycogen accumulation requires further investigation. To reduce the potential risk of cardiovascular diseases, we recommend that blood pressure and other common cardiovascular risk factors are monitored regularly.  相似文献   
66.
Journal of Thrombosis and Thrombolysis - Direct oral anti-coagulants (DOACs) reduce hospital length-of-stay (LOS) in patients with acute pulmonary embolism (PE) in clinical trials. There is a...  相似文献   
67.
Annals of Hematology - The prognostic significance of hypercalcemia in lymphoma has only been studied on small series to date. We conducted a retrospective, monocentric, matched-control study that...  相似文献   
68.
Abstract

Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder characterized by defective biogenesis of lysosome-related organelles. Clinical manifestations include a bleeding diathesis due to a platelet delta storage pool deficiency, oculocutaneous albinism, inflammatory bowel disease, neutropenia, and pulmonary fibrosis. Ten genes associated with HPS are identified to date, and each gene encodes a protein subunit of either Biogenesis of Lysosome-related Organelles Complex (BLOC)-1, BLOC-2, BLOC-3, or the Adaptor Protein-3 complex. Several genetic variants and phenotypic heterogeneities are reported in individuals with HPS, who generally exhibit easy bruisability and increased bleeding. Desmopressin, pro-coagulants, or platelet transfusion may be used as prophylaxis or treatment for excessive bleeding in patients with HPS. However, response to desmopressin can be variable. Platelets are effective in preventing or treating bleeding in individuals with HPS, but platelets should be transfused judiciously to limit alloimmunization in patients with HPS who are at risk of developing pulmonary fibrosis and may be potential candidates for lung transplantation. The discovery of new genes associated with HPS in people with excessive bleeding and hypopigmentation of unknown etiology may be facilitated by the use of next-generation sequencing or panel-based genetic testing.  相似文献   
69.
The basal ganglia (BG) mediate certain types of procedural learning, such as probabilistic classification learning on the ‘weather prediction task’ (WPT). Patients with Parkinson's disease (PD), who have BG dysfunction, are impaired at WPT‐learning, but it remains unclear what component of the WPT is important for learning to occur. We tested the hypothesis that learning through processing of corrective feedback is the essential component and is associated with release of striatal dopamine. We employed two WPT paradigms, either involving learning via processing of corrective feedback (FB) or in a paired associate manner (PA). To test the prediction that learning on the FB but not PA paradigm would be associated with dopamine release in the striatum, we used serial 11C‐raclopride (RAC) positron emission tomography (PET), to investigate striatal dopamine release during FB and PA WPT‐learning in healthy individuals. Two groups, FB, (n = 7) and PA (n = 8), underwent RAC PET twice, once while performing the WPT and once during a control task. Based on a region‐of‐interest approach, striatal RAC‐binding potentials reduced by 13–17% in the right ventral striatum when performing the FB compared to control task, indicating release of synaptic dopamine. In contrast, right ventral striatal RAC binding non‐significantly increased by 9% during the PA task. While differences between the FB and PA versions of the WPT in effort and decision‐making is also relevant, we conclude striatal dopamine is released during FB‐based WPT‐learning, implicating the striatum and its dopamine connections in mediating learning with FB. Hum Brain Mapp 35:5106–5115, 2014. © 2014 The Authors. Human Brain Mapping Published by Wiley Periodicals, Inc.  相似文献   
70.
The present systematic review and metaanalysis of published observational studies was conducted to assess the health effects of exposure to air pollution on diabetes risk. Online databases were searched through January 2013, and the reference lists of pertinent articles reporting observational studies in humans were examined. Pooled relative risks and 95 % confidence intervals were calculated with a random-effects model. Exposure to air pollution was associated with slight increase in risk of diabetes and susceptibility of people with diabetes to air pollution. These results were consistent between time-series, case-crossover and cohort studies and between studies conducted in North America and Europe. The association between exposure to air pollution and diabetes was stronger for gaseous pollutants than for particulate matter. Our metaanalysis suggests that exposure to air pollution may be a risk factor for diabetes and increase susceptibility of people with diabetes to air pollution.  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