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   1184221篇
  免费   77039篇
  国内免费   1800篇
耳鼻咽喉   17212篇
儿科学   34421篇
妇产科学   30683篇
基础医学   168840篇
口腔科学   34817篇
临床医学   99432篇
内科学   229701篇
皮肤病学   26270篇
神经病学   93769篇
特种医学   48904篇
外国民族医学   148篇
外科学   192311篇
综合类   20470篇
现状与发展   1篇
一般理论   292篇
预防医学   74474篇
眼科学   28336篇
药学   90252篇
  3篇
中国医学   2784篇
肿瘤学   69940篇
  2018年   12363篇
  2017年   9779篇
  2016年   11540篇
  2015年   13135篇
  2014年   16779篇
  2013年   24544篇
  2012年   34312篇
  2011年   34938篇
  2010年   20809篇
  2009年   19422篇
  2008年   34286篇
  2007年   36404篇
  2006年   37229篇
  2005年   36626篇
  2004年   35421篇
  2003年   34159篇
  2002年   33612篇
  2001年   64846篇
  2000年   66722篇
  1999年   55838篇
  1998年   13395篇
  1997年   11857篇
  1996年   11551篇
  1995年   10669篇
  1994年   9859篇
  1993年   9136篇
  1992年   40652篇
  1991年   38921篇
  1990年   37805篇
  1989年   36598篇
  1988年   33239篇
  1987年   32397篇
  1986年   30343篇
  1985年   28969篇
  1984年   20719篇
  1983年   17493篇
  1982年   9277篇
  1981年   8181篇
  1979年   18690篇
  1978年   12731篇
  1977年   10827篇
  1976年   9413篇
  1975年   10720篇
  1974年   12624篇
  1973年   11872篇
  1972年   11250篇
  1971年   10706篇
  1970年   10072篇
  1969年   9450篇
  1968年   8659篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
The frequency and pathophysiology of freezing of gait (FoG) in atypical parkinsonism is unknown. We analysed the frequency of FoG in postmortem-confirmed atypical parkinsonian disorders (APD) comprising corticobasal degeneration (CBD), dementia with Lewy bodies (DLB), multiple system atrophy (MSA), and progressive supranuclear palsy (PSP). Sixty-six patients with pathologically confirmed APD (CBD, n = 13; DLB, n = 14; MSA, n = 15; PSP, n = 24) formed the basis for a multicenter clinicopathological study. Clinical features at first and last clinical visit were abstracted from patient records on standardized forms following strict instructions. At the first visit (median 36 months after symptom onset), 24% of APD had FoG (CBD, 8%; DLB, 21%; PSP, 25%; MSA, 40%). Logistic regression analysis showed a significant association of FoG and urinary incontinence (P = 0.04) at first visit. At last visit, 47% of APD had FoG (CBD, 25%; PSP, 53%; DLB, 54%; MSA, 54%). Clinicopathological correlation based on routine postmortem examination failed to identify a consistent neuropathological substrate of FoG. This study demonstrates that (1) FoG is common in APD, and (2) urinary incontinence is significantly associated with FoG in these disorders. Whether FoG and urinary incontinence share similar neuropathological substrates remains to be determined by future studies.  相似文献   
63.
64.
65.
Computed tomography (CT) is currently the imaging modality of choice for assessing the morphology of the adrenal glands in adult patients. Much useful information can be gained using CT in disease processes which primarily involve one or both of the adrenal glands, such as adenomas, as well as in entities which secondarily affect the adrenals, such as pituitary or metastatic disease. The size and configuration of the glands can be readily determined, and masses may be detected. We discuss CT of normal and abnormal adrenal glands with sonographic (US) and pathological correlation, when available. Entities which may mimic adrenal abnormalities are emphasized. Relative advantages of US over CT in the pediatric patient are discussed.  相似文献   
66.
The Dundee Memory Clinic was established in 1991. This paper reviews the diagnosis of the first 150 attenders and compares the findings with those of other memory clinics.  相似文献   
67.
Fibroblasts incorporated within collagen gels induce a cell-mediated contraction of the gel to form a three-dimensional, tissue-like structure by a mechanism thought to mimic wound contraction in vivo . In this study a gel contraction model was used to investigate the ability of fibroblasts derived from adult gingiva, adult skin and fetal skin to organise a collagen matrix. In addition the effects of interleukin-1β (IL-1β) on the contraction process was also investigated. Over the concentration range 5-50 U/ml, IL-1β induced a statistically significant inhibition of gel contraction in all fibroblast cell types ( P <0.05), although fetal fibroblasts appeared least responsive and gingival fibroblasts most responsive to the inhibitory effects of this cytokine. Comparison of gel contraction by the different fibroblast strains indicated that fetal and gingival fibroblasts shared similar contraction kinetics. For the adult skin fibroblasts, three of five strains studied showed significantly diminished levels of gel contraction compared to fetal and gingival cells. This apparent difference in fibroblast phenotype may, at least in part, explain the fetal-like wound healing pattern seen in the oral mucosa.  相似文献   
68.
The diagnosis of acute disseminated encephalomyelitis (ADEM) is frequently missed or delayed with consequent delay in instituting therapy in the crucial phase of the illness. The role of MRI in the diagnosis of ADEM is well established, however, the value of its early utilization of treatment on the outcome of patients has not been adequately stressed. Three patients with ADEM are described. Delay in the diagnosis of the first was associated with severe sequelae, while in the other two early diagnosis and institution of corticosteroid therapy which was facilitated by MRI, was associated with a better outcome. MRI should be carried out early once the diagosis of ADEM is entertained.  相似文献   
69.
The value of ultrasound in the diagnosis of a large rapidly growing thyroid mass was assessed in a study of 42 patients with a large (> 3 cm) rapidly growing (< two months) solitary mass. Haemorrhage into a thyroid nodule was present in 31 patients and thyroid malignancy in 11. Ultrasound of haemorrhage into a thyroid nodule revealed a large cystic mass in all 31 patients containing internal debris (22), septations (three), or a combination of both (six). The malignant causes of a large rapidly growing mass were lymphoma (two), anaplastic carcinoma (four) and metastasis (five). Ultrasound of these thyroid malignancies revealed a mass with a smooth, well-defined margin and strikingly low homogeneous echogenicity in all cases. Patients with thyroid metastases had evidence of widespread metastatic disease elsewhere. Lymphoma was differentiated from anaplastic carcinoma on fine-needle aspiration cytology or surgical biopsy. Ultrasound was of value in differentiating between a benign haemorrhagic nodule and a malignant tumour. The various malignant tumours had similar appearances, however, and could not be distinguished on ultrasound.  相似文献   
70.
PURPOSETo study the relationship of lumbar facet joint tropism to degeneration of the cartilage and subcortical bone in the facet joints and the effect of tropism in intervertebral disk degeneration.METHODSThe orientation of 104 cadaveric lumbar facet joints with respect to sagittal plane was measured on CT scans, and the joints were classified as having no tropism, mild tropism, or severe tropism. On MR images, the severity of cartilage degeneration and bony sclerosis was measured. The correlation between tropism and degeneration was calculated, as was the relationship among age, spinal level, and degeneration.RESULTSWe identified four spinal levels with severe tropism, six with moderate tropism, and 94 without tropism. Cartilage degeneration was not significantly more severe in the joints with tropism than in the joints without. Sclerosis was slightly greater in the joints with tropism than in the joints without it. Sclerosis and cartilage degeneration were significantly related to age and spinal level.CONCLUSIONAge, spinal level, and overall facet joint angle are more important factors in facet joint degeneration than is tropism.  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