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   1366911篇
  免费   86219篇
  国内免费   2829篇
耳鼻咽喉   18581篇
儿科学   43580篇
妇产科学   37170篇
基础医学   208797篇
口腔科学   36405篇
临床医学   118460篇
内科学   265536篇
皮肤病学   29468篇
神经病学   101097篇
特种医学   53401篇
外国民族医学   381篇
外科学   210019篇
综合类   25907篇
现状与发展   2篇
一般理论   349篇
预防医学   99602篇
眼科学   30931篇
药学   100331篇
  1篇
中国医学   2858篇
肿瘤学   73083篇
  2018年   14240篇
  2017年   10799篇
  2016年   12086篇
  2015年   13578篇
  2014年   18842篇
  2013年   28710篇
  2012年   39722篇
  2011年   43100篇
  2010年   25586篇
  2009年   23647篇
  2008年   40190篇
  2007年   43286篇
  2006年   42936篇
  2005年   41805篇
  2004年   40335篇
  2003年   38868篇
  2002年   38020篇
  2001年   60029篇
  2000年   61566篇
  1999年   51856篇
  1998年   14478篇
  1997年   12901篇
  1996年   12809篇
  1995年   11998篇
  1994年   11233篇
  1993年   10700篇
  1992年   40465篇
  1991年   40549篇
  1990年   40162篇
  1989年   38867篇
  1988年   35943篇
  1987年   35542篇
  1986年   33700篇
  1985年   32242篇
  1984年   24043篇
  1983年   20492篇
  1982年   11763篇
  1979年   22493篇
  1978年   15878篇
  1977年   13205篇
  1976年   13067篇
  1975年   14880篇
  1974年   17332篇
  1973年   16589篇
  1972年   15589篇
  1971年   14606篇
  1970年   13947篇
  1969年   13007篇
  1968年   12342篇
  1967年   11237篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
OBJECTIVE: Spinal reflexes from hand to wrist muscles were investigated in writer's cramp. METHODS: Stimulus-triggered rectified EMG averages after ulnar nerve and cutaneous stimulation, in wrist flexors and extensors during tonic contraction, were compared in 18 controls and 19 patients. RESULTS: On the patient dystonic side, ulnar-induced EMG suppression was decreased in wrist extensors, and facilitation in wrist flexors modified dependent on the dystonic wrist posture during writing. No change was found on the patient non-dystonic side. Cutaneous stimulation increased wrist flexor EMG on both sides of the patients with normal wrist posture during writing, but had no effect in controls and patients with abnormal wrist posture. CONCLUSIONS: Comparison between cutaneous and mixed nerve stimuli suggests that spindle afferents from intrinsic hand muscles may mediate patients' ulnar-induced EMG modulations. Abnormal proprioceptive control was only observed on dystonic side, while bilateral unusual cutaneous control was found in patients. Changes in spinal transmission were partly related to the dystonic wrist posture, suggesting that systems involved in sensory processing can be differentially altered in writer's cramp. SIGNIFICANCE: Changes in spinal transmission, probably related to peripheral and/or cortical inputs, might either take part in primary or adaptive mechanisms underlying writer's cramp.  相似文献   
22.
Vitiligo and psoriasis are both common skin disorders. However, psoriasis strictly confined to pre-existing vitiligo areas is rare and suggests a causal relationship. We report here on two patients with a strict anatomical colocalization of vitiligo and psoriasis. The histopathological examinations showed typical changes for both diseases together with a dense infiltrate of CD4+ and CD8+ T cells. By immunohistochemistry, intracytoplasmatic granzyme B and tumour necrosis factor alpha (TNF-alpha) were detected within the T-cell population, suggesting the functional activity of these cells and the creation of a local T helper 1 (Th1)-cytokine milieu. Additionally, in one patient we could identify anti-melanocytic T cells by tetramer staining and enzyme-linked immunospot (ELISPOT) analysis. These skin-infiltrating lymphocytes might trigger, by the local production of Th-1 cytokines such as TNF-alpha and interferon-gamma (IFN-gamma), the eruption of psoriatic plaques in patients with a genetic predisposition for psoriasis.  相似文献   
23.
AIM: Cardiovascular risk factors can be present in children and young adults. We previously found abnormal microvascular function in children who had glucose intolerance and insulin resistance. The aim of the present study was to investigate whether they also have abnormalities in left ventricular mass (LVM) and arterial stiffness. METHODS: We measured heart dimensions and LVM using echocardiography, and arterial stiffness using pulse wave analysis in 23 children with good glucose handling (postfeeding glucose: 3.9 to 5 mmol/L) and 21 with poor glucose handling (7.7 to 11.4 mmol/L). RESULTS: The time to pulse reflection was slightly shorter in the poorer glucose handlers (mean+/-SD: 143+/-10 vs 153+/-20 ms, P=0.04), suggestive of increased arterial stiffness. Also in this group, there were significant relationships between intraventricular septal thickness, blood pressure and body mass index, but not in the normal glucose handlers. CONCLUSIONS: We have found that normal children who are in the lowest quintile of glucose tolerance in comparison with their peers are exhibiting the first signs of arterial stiffening. In addition, we have seen the beginnings of a relationship between blood pressure, body mass index and left ventricular enlargement in this group. While these changes may not yet be clinically significant, their emergence might be further evidence of early predisposition to cardiovascular disease.  相似文献   
24.
25.
Setting goals to maintain hope.   总被引:3,自引:0,他引:3  
  相似文献   
26.
27.
Medullary thyroid carcinoma (MTC) is a rare form of thyroid cancer representing about 10% of all thyroid malignancies. It occurs mostly as a sporadic tumor or in association with autosomal dominant inherited cancer syndromes--multiple endocrine neoplasia (MEN) types 2A and 2B and familial MTC. Germline mutations in exons 8, 10, 11, 13, 14, 15 and 16 of the RET proto-oncogene are found in most of the familial cases. There are only a few published data reporting multiple germline mutations in the RET proto-oncogene. We have detected double germline mutations in 2 different exons on the same RET allele in two MEN 2 families. In the MEN 2A family, double germline mutation in exons 10 (Cys620Phe) and 13 (Tyr791Phe) was detected. In the MEN 2B family, beside the classical germline mutation in exon 16 (Met918Thr) a second germline mutation in exon 13 (Tyr791Phe) was found. This study revealed that MEN 2 syndromes can also be caused by double germline mutations in the RET proto-oncogene and these families can be added to small worldwide cohort of families with multiple germline mutations.  相似文献   
28.
Sniff nasal inspiratory pressure (SNIP) measurement is a volitional noninvasive assessment of inspiratory muscle strength. A maximum of 10 sniffs is generally used. The purpose of the present study was to investigate whether the maximum SNIP improved after the tenth sniff. In total, 20 healthy volunteers and 305 patients with various neuromuscular and lung diseases were encouraged to perform 40 and 20 sniffs, respectively. The best SNIP among the first 10 sniffs was lower than the best SNIP among the next 10 sniffs in the healthy volunteers and patients. The SNIP improvement after the twentieth sniff was marginal. In conclusion, a learning effect persists after the tenth sniff. The current authors suggest using 10 additional sniffs when the best result of the first 10 sniffs is slightly below normal, or when sniff nasal inspiratory pressure is used to monitor a progressive decline in inspiratory muscle strength.  相似文献   
29.
30.
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