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   53474篇
  免费   3776篇
  国内免费   260篇
耳鼻咽喉   521篇
儿科学   1919篇
妇产科学   1369篇
基础医学   8022篇
口腔科学   791篇
临床医学   5159篇
内科学   12129篇
皮肤病学   1174篇
神经病学   5901篇
特种医学   1124篇
外科学   4364篇
综合类   297篇
现状与发展   1篇
一般理论   43篇
预防医学   5028篇
眼科学   869篇
药学   4056篇
中国医学   136篇
肿瘤学   4607篇
  2024年   91篇
  2023年   682篇
  2022年   1438篇
  2021年   2427篇
  2020年   1397篇
  2019年   1789篇
  2018年   1968篇
  2017年   1594篇
  2016年   1752篇
  2015年   1902篇
  2014年   2472篇
  2013年   3101篇
  2012年   4562篇
  2011年   4562篇
  2010年   2421篇
  2009年   2067篇
  2008年   3447篇
  2007年   3438篇
  2006年   3103篇
  2005年   2825篇
  2004年   2617篇
  2003年   2333篇
  2002年   2105篇
  2001年   239篇
  2000年   183篇
  1999年   252篇
  1998年   335篇
  1997年   285篇
  1996年   193篇
  1995年   183篇
  1994年   182篇
  1993年   142篇
  1992年   99篇
  1991年   84篇
  1990年   65篇
  1989年   77篇
  1988年   72篇
  1987年   65篇
  1986年   59篇
  1985年   59篇
  1984年   83篇
  1983年   68篇
  1982年   78篇
  1981年   66篇
  1980年   61篇
  1979年   29篇
  1978年   33篇
  1977年   34篇
  1976年   25篇
  1975年   20篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
121.
A 15-week old male infant presented with bilateral lower motor neuron facial palsy of unknown cause. Subsequently his growth deteriorated and he developed progressively worsening cough and wheeze. A diagnosis of cystic fibrosis was confirmed and hypovitaminosis A detected. Improvement of the facial palsy was noted following standard management of cystic fibrosis including vitamin A supplementation.  相似文献   
122.
We report the collaboration between the First Postgraduate School of Obstetrics and Gynecology at the University of Milan, Italy, and the nongovernmental organization “Emergency” that operates through its own hospitals in countries devastated by armed conflicts. The collaboration was centered on the maternity clinic that Emergency opened in 2003 in northern Afghanistan. After a woman resident spent 5 months on-site, the collaboration is now extended to all residents with a group with four areas of intervention: guidelines, clinical records and data collection, drugs and medical devices, and teaching material. In addition, it offers consultation by e-mail for any clinical issue that might arise.  相似文献   
123.
Deficits in visual-spatial ability can be associated with Parkinson's disease (PD), and there are several possible reasons for these deficits. Dysfunction in frontal-striatal and/or frontal-parietal systems, associated with dopamine deficiency, might disrupt cognitive processes either supporting (e.g., working memory) or subserving visual-spatial computations. The goal of this study was to assess visual-spatial orientation ability in individuals with PD using the Mental Rotations Test (MRT), along with other measures of cognitive function. Non-demented men with PD were significantly less accurate on this test than matched control men. In contrast, women with PD performed similarly to matched control women, but both groups of women did not perform much better than chance. Further, mental rotation accuracy in men correlated with their executive skills involving mental processing and psychomotor speed. In women with PD, however, mental rotation accuracy correlated negatively with verbal memory, indicating that higher mental rotation performance was associated with lower ability in verbal memory. These results indicate that PD is associated with visual-spatial orientation deficits in men. Women with PD and control women both performed poorly on the MRT, possibly reflecting a floor effect. Although men and women with PD appear to engage different cognitive processes in this task, the reason for the sex difference remains to be elucidated.  相似文献   
124.
Summary We propose that the secreted protein pleiotrophin (PTN) is a major factor in the malignant progression of breast cancer. This hypothesis is based on the growth-stimulatory effects of PTN on cellsin vitro andin vivo and on its high levels of expression in 60% of tumor samples from breast cancer patients. The stimulation of proliferation and tube formation of endothelial cells by PTN suggests that it can serve as an angiogenesis factor during tumor growth. We hypothesize that PTN has the potential to support growth of breast cancer at its primary site and to enhance the ability of tumor cells to metastasize. Furthermore, we suggest that specific endocrine signals interact to regulate the expression of PTNin vitro andin vivo. Finally, we propose that understanding the functions of PTN and its hormonal regulation can lead to the development of novel therapeutic strategies for breast cancer.  相似文献   
125.
126.
Many current generativist theorists suggest that young children possess the grammatical principles of inversion required for question formation but make errors because they find it difficult to learn language-specific rules about how inversion applies. The present study analyzed longitudinal spontaneous sampled data from twelve 2-3-year-old English speaking children and the intensive diary data of 1 child (age 2;7 [years;months] to 2;11) in order to test some of these theories. The results indicated significantly different rates of error use across different auxiliaries. In particular, error rates differed across 2 forms of the same auxiliary subtype (e.g., auxiliary is vs. are), and auxiliary DO and modal auxiliaries attracted significantly higher rates of errors of inversion than other auxiliaries. The authors concluded that current generativist theories might have problems explaining the patterning of errors seen in children's questions, which might be more consistent with a constructivist account of development. However, constructivists need to devise more precise predictions in order to fully explain the acquisition of questions.  相似文献   
127.
BACKGROUND: Congenital absence of the inferior rectus muscle is a rare cause of apparent inferior rectus palsy especially in the absence of associated cranial facial anomalies. METHODS: We report three cases of isolated congenital absence of the inferior rectus muscle and its successful surgical management. RESULTS: Failure of the normal embryologic development of the mesodermal complex around the eye can lead to agenesis of the extraocular muscles. In apparent palsies of the inferior rectus muscle and no definite cause, a high index of suspicion and orbital imaging can confirm the diagnosis of congenitally absent inferior rectus preoperatively. Surgical correction may involve inferior transposition of the horizontal rectus muscles. CONCLUSIONS: Although rare, congenital absence of the inferior rectus muscle is a possible cause of apparent inferior rectus muscle palsy particularly in the absence of another identifiable cause. Strabismus surgery in conjunction with intramuscular botulinum toxin injection can offer significant improvement in function and cosmesis of these patients.  相似文献   
128.
In the present study, morphological examination of patients from two unrelated Polish families with CADASIL was performed. Using light microscopy, there were evident changes characteristic to the disease. On electron microscopy, deposits of granular osmiophillic material (GOM) were found not only in cerebral arteries and veins but also in cerebral capillaries and vessels of the internal organs. These findings indicate that pathological process in CADASIL is generalized and involves also small vessels devoid of smooth muscle cells. Therefore, we propose to consider a replacement for the name CADASIL that better reflects the morphological picture of the disease like, for example, cerebral autosomal dominant vasculopathy with subcortical infarcts and leukoencephalopathy (CADVaSIL) or, to preserve the commonly known acronym, cerebral autosomal dominant angiopathy with subcortical infarcts and leukoencephalopathy.  相似文献   
129.
PURPOSE: Although the angle of deviation in patients with congenital esotropia has been shown to increase during the early preoperative period, few data exist regarding this change in other forms of childhood esotropia. The primary objective of this study was to investigate whether the angle of deviation increases with time in patients with acquired nonaccommodative esotropia (ANAET). METHODS: The medical records of all children whose ANAET was diagnosed at East Tennessee State University College of Medicine from August 1, 1995, through October 1, 2001, were retrospectively reviewed. All patients were assessed for any change in the amount of their strabismic angle and associated risk factors. RESULTS: Eighty-two patients with ANAET were identified, and all except 3 underwent more than one examination. Of the 79 children who underwent more than one examination, 26 (32.9%) displayed an angle increase of > or =10 prism diopters (PD) during a median follow-up period of 2.9 months. The ANAET of those patients whose angle increased by > or =10 PD was diagnosed (28.4 months of age vs 45.5 months of age, P =.003), and they underwent surgery (35.9 months of age vs 53.3 months of age, P =.003) at a significantly younger median age than those whose angle increased <10 PD. CONCLUSIONS: The angle of deviation of approximately one third of patients with ANAET in this study increased at least 10 PD in the early preoperative period. This increase occurs more often in younger patients and underscores the importance of performing serial measurements of the deviating angle before surgical intervention is undertaken.  相似文献   
130.
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