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   3207篇
  免费   233篇
  国内免费   8篇
耳鼻咽喉   76篇
儿科学   70篇
妇产科学   78篇
基础医学   437篇
口腔科学   47篇
临床医学   350篇
内科学   594篇
皮肤病学   60篇
神经病学   274篇
特种医学   157篇
外科学   612篇
综合类   21篇
预防医学   179篇
眼科学   67篇
药学   196篇
中国医学   1篇
肿瘤学   229篇
  2022年   28篇
  2021年   60篇
  2020年   31篇
  2019年   41篇
  2018年   73篇
  2017年   45篇
  2016年   71篇
  2015年   90篇
  2014年   110篇
  2013年   140篇
  2012年   174篇
  2011年   207篇
  2010年   127篇
  2009年   117篇
  2008年   145篇
  2007年   136篇
  2006年   174篇
  2005年   148篇
  2004年   116篇
  2003年   128篇
  2002年   105篇
  2001年   73篇
  2000年   105篇
  1999年   92篇
  1998年   48篇
  1997年   23篇
  1996年   32篇
  1995年   19篇
  1994年   22篇
  1993年   24篇
  1992年   46篇
  1991年   46篇
  1990年   46篇
  1989年   31篇
  1988年   50篇
  1987年   38篇
  1986年   41篇
  1985年   29篇
  1984年   24篇
  1983年   21篇
  1982年   28篇
  1980年   20篇
  1979年   22篇
  1978年   20篇
  1977年   20篇
  1975年   17篇
  1973年   22篇
  1972年   16篇
  1970年   16篇
  1968年   18篇
排序方式: 共有3448条查询结果,搜索用时 15 毫秒
41.
Ectomesenchymal chondromyxoid tumor is a rare neoplasm of uncertain histogenesis that typically occurs in the anterior dorsal tongue. Recent reports in the literature have described rare examples of gingival, palatal and tonsillar lesions. Histologically, ectomesenchymal chondromyxoid tumors are typically well-circumscribed, lacking overtly aggressive features. Herein we report a tumor arising in the right mandible that is morphologically and molecularly consistent with ectomesenchymal chondromyxoid tumor. This case furthers awareness of the extra-glossal distribution of this neoplasm; moreover, it suggests that a subset of these tumors have the potential for locally aggressive behaviour.Electronic supplementary materialThe online version of this article (10.1007/s12105-020-01169-5) contains supplementary material, which is available to authorized users.  相似文献   
42.
The complexity of homelessness suggests that the development of policy and service strategies requires careful analysis of the unique features of identifiable groups within the homeless population. To begin this process, the characteristics and needs of homeless women are specified and their routes to homelessness delineated. Responses to homeless women, with the exception of battered women, have focused primarily on the provision of emergency services. Future policy and services must focus on the adequacy and accessibility of these emergency services as well as the need for transitional and long term housing and social services. The multidimensional nature of homelessness and the heterogeneity of homeless women require a wide range of alternatives that can be tailored to each woman's unique needs for service.  相似文献   
43.
Amphiphilic chains of 4-benzoylbenzoic acid moieties and polymer were photochemically immobilized onto silicone rubber to ask whether the covalently coupled polymers would passivate the silicone rubber by inhibiting protein adsorption and subsequent cell adhesion and activation. Three groups of polymers were utilized: the hydrophilic synthetic polymers of polyacrylamide, polyethylene glycol, and polyvinylpyrrolidone; the glycosaminoglycan, hyaluronic acid; and poly(glycine-valine-glycine-valine-proline), a polypeptide derived from the sequence of elastin. Each coating variant decreased the adsorption of fibrinogen and immunoglobulin G compared to uncoated silicone rubber. All except the methoxy-polyethylene glycol coating nearly abolished fibroblast growth, but none of the coating variants inhibited monocyte or polymorphonuclear leukocyte adhesion. Interleukin-1beta, interleukin-1 receptor antagonist, and tumor necrosis factor-alpha secretion by leukocytes were not statistically different between any of the coating variants and uncoated silicone rubber. However, the methoxy-polyethylene glycol and elastin-based polypeptide coatings, which supported the highest numbers of adherent monocytes, also elicited the lowest levels of proinflammatory cytokine secretion. When these in vitro data were collectively evaluated, the coating that most effectively passivated silicone rubber was the polypeptide derived from elastin.  相似文献   
44.
OBJECTIVE: The purpose of this study was to assess whether the extent of intestinal metaplasia is related to the severity of the gastroesophageal reflux disease. METHODS: A total of 556 consecutive patients with symptoms suggestive of foregut disease had upper gastrointestinal endoscopy with extensive biopsies from the gastroesophageal junction and the esophagus. All patients had esophageal motility and 24-hour pH monitoring. In 411 patients, cardiac-type mucosa was identified; in 147 patients, the cardiac-type mucosa showed intestinal metaplasia. They were divided into 3 groups based on the extent of intestinal metaplasia commonly seen clinically: long segments (>3 cm), short segments (<3 cm), and limited to the gastroesophageal junction. The duration of symptoms, the status of the lower esophageal sphincter, the degree of esophageal acid exposure, and the time to clear a reflux episode were assessed in each group. RESULTS: The presence of intestinal metaplasia in cardiac-type mucosa was associated with the hallmarks of gastroesophageal reflux disease. The extent of intestinal metaplasia correlated strongly with the degree of esophageal acid exposure (r = 0.711; P <.001) and inversely with the lower esophageal sphincter pressure (r = 0.351; P <.001) and length (r = 0. 259; P =.002). Patients with a long segment of intestinal metaplasia (>3 cm) had longer duration of symptoms (16 years) than those patients with a segment of intestinal metaplasia less than 3 cm (10 years; P =.048) or those patients with intestinal metaplasia limited to the gastroesophageal junction (10 years; P =.01). CONCLUSION: The extent of intestinal metaplasia, that is, Barrett's esophagus, is related to the status of the lower esophageal sphincter and the degree of esophageal acid exposure.  相似文献   
45.
We have compared three different methods of epidural analgesia in labour, bupivacaine 2.5 mg/ml (group B), bupivacaine 0.625 mg/ml + sufentanil 1 microg/ml (group BS) and bupivacaine 0.625 mg/ml + sufentanil 1 microg/ml + epinephrine 1 microg/ml (group BSE). One hundred and forty parturients with a singleton fetus with cephalic presentation were randomly allocated to one of the three groups. Group BSE had significantly less pain than groups B and BS. Group B had a significantly higher degree of motor blockade assessed on the Bromage scale. Significantly, more women in group B required urinary bladder catheterization than in the two other groups and they also had significantly less urge to push during active delivery. The incidence of mild pruritus was 18% in group BS and 36% in group BSE. The frequency of instrumental delivery and caesarean section was low (12% and 6.4%, respectively) with no significant differences between the groups. All women were highly satisfied with the method of analgesia and 97% would prefer the same kind of pain alleviation at the next delivery. We conclude that epidural analgesia with low-dose bupivacaine and sufentanil is as good an analgesic method as high-dose bupivacaine. Addition of low-dose epinephrine improves the analgesia.  相似文献   
46.
Patients with an acute "brain damage" where an intracranial pressure rise can be suspected due to the pathophysiological context are an indication for intracranial pressure measurement. For registrating the reduction of the intracranial reserve space before the rise of the medium pressure, volume-loads from the side-ventricles were undertaken with 54 neurosurgical patients. A better bedside monitoring is possible though the mathematical registration of those factors which indicate the size of the functional intracranial reserve space. With the calculated parameters of the reserve space (pressure-volume-index) a theoretical pressure-volume-curve was demonstrated.  相似文献   
47.
Hagen EM  Eriksen HR  Ursin H 《Spine》2000,25(15):1973-1976
STUDY DESIGN: A controlled randomized clinical trial was performed. OBJECTIVE: To investigate the effect of a light mobilization program on the duration of sick leave for patients with subacute low back pain. SUMMARY OF BACKGROUND DATA: Early intervention with information, diagnostics, and light mobilization may be a cost-effective method for returning patients quickly to normal activity. In this experiment, patients were referred to a low back pain clinic and given this simple and systematic program as an outpatient treatment. METHODS: In this study, 457 patients sick-listed 8 to 12 weeks for low back pain, as recorded by the National Insurance Offices, were randomized into two groups: an intervention group (n = 237) and a control group (n = 220). The intervention group was examined at a spine clinic and given information and advice to stay active. The control group was not examined at the clinic, but was treated with conventional primary health care. RESULTS: At 12-month follow-up assessment, 68.4% in the intervention group had returned to full-duty work, as compared with 56.4% in the control group. CONCLUSIONS: Early intervention with examination, information, and recommendations to stay active showed significant effects in reducing sick leave for patients with low back pain.  相似文献   
48.
BACKGROUND: Wegener's granulomatosis (WG) is characterized by systemic vasculitis with crescentic glomerulonephritis (CGN) and circulating autoantibodies directed against neutrophil cytoplasmic antigens (ANCA). Proteinase 3 (PR-3), a neutral serine proteinase in neutrophils implicated in the growth control of myeloid cells, has been identified as the target antigen for ANCA in WG. Since the kidneys are frequently involved in WG, we studied the in situ expression of PR-3 by renal parenchymal cells. METHODS: We assessed the expression of PR-3 in kidney biopsies of 15 patients with WG by immunohistochemistry (IHC) and in situ hybridization (ISH). Normal kidney tissue served as the control. RESULTS: We detected PR-3 mRNA and PR-3 protein in distal tubular epithelial cells (TECs) and glomerular epithelial cells (GECs) in normal kidney tissue and in CGN. Furthermore, a strong glomerular PR-3mRNA expression restricted to the site of cellular crescents was detected in patients with WG. The analysis of 144 glomeruli with cellular or sclerotic crescents revealed a positive correlation of glomerular PR-3mRNA expression with the percentage of cellular crescents per glomerulus. The capability of human TECs and GECs to synthesize PR-3 was confirmed by Northern blot and ISH on cultured cells. CONCLUSION: These data provide evidence that nonhematopoetic renal parenchymal cells express PR-3 and that glomerular expression of PR-3 is associated with crescent formation in WG. Our findings suggest that renal parenchymal cells may directly be involved in the pathogenesis of CGN in WG.  相似文献   
49.
AIMS: To review the development and current status of balloon catheter mediated hypoxic perfusion of abdomen, pelvis and liver for treatment of locally advanced malignancies. Within this context we focus on the addition of tumour necrosis factor-alpha (TNF) to these minimal invasive perfusion procedures. METHODS: A literature search on these topics was carried out in PubMed for indexed articles and in all issues of Regional Cancer Treatment. The findings were related to our own experiences. RESULTS: Hypoxic abdominal (HAP) and hypoxic pelvic perfusion (HPP) using balloon catheters, are currently applied modalities for treatment of a wide variety of abdominal and pelvic tumours, yet scientific validation of these procedures is poor. Following the results of several Phase I-II trials, both treatments are associated with severe systemic toxicity, significant morbidity and even mortality. The degree of systemic leakage associated with these procedures prohibits addition of TNF. For leakage free liver perfusion surgery is still required, as with current balloon catheter techniques it is not possible to perform leakage free isolated hypoxic hepatic perfusion (IHHP), using either orthograde or retrograde hepatic flow. Experimental and clinical observations suggest that within any perfusion setting, the utilization of TNF is only indicated for treatment of highly vascularised tumours and not for treatment of colorectal tumours. CONCLUSION: Balloon catheter technology in its present form does not provide adequate leakage control in any of these settings and is therefore associated with considerable toxicity. It is associated with poor response rates and cannot be considered in any setting as a standard of care.  相似文献   
50.
Objectives: Systemic mastocytosis (SM) is a myeloproliferative disease characterized by the accumulation of aberrant mast cells. Since advanced subtypes of SM can lead to organ dysfunction and shortened survival, timely recognition of progressive disease is important for the adequate treatment of SM patients.

Methods: Here, we report the results of our cohort study on the value of routine abdominal ultrasonography for the detection of progression of indolent systemic mastocytosis (ISM).

Results: We included 88 patients with ISM, of whom 9 developed new hepatosplenomegaly during follow-up. In this group, the median serum tryptase level increased by 11.60?μg/l, compared with a decrease of ?0.20?μg/l in the 79 patients with unchanged ultrasonography results (p?=?0.016). A change in liver and/or spleen size never led to a change in clinical classification, nor management.

Discussion: Based on the finding that a change in ultrasonography findings did not correlate to disease progression in general, it appears that isolated hepatosplenomegaly does not have prognostic implications in patients with ISM.

Conclusions: Routine abdominal ultrasonography is redundant in the follow-up of patients with ISM. A combination of physical examination with serum tryptase levels can be used to screen for hepatosplenomegaly.  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