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   32180篇
  免费   1195篇
  国内免费   177篇
耳鼻咽喉   387篇
儿科学   607篇
妇产科学   266篇
基础医学   4065篇
口腔科学   769篇
临床医学   2003篇
内科学   8249篇
皮肤病学   792篇
神经病学   2574篇
特种医学   1238篇
外科学   5522篇
综合类   129篇
一般理论   3篇
预防医学   856篇
眼科学   529篇
药学   1980篇
  4篇
中国医学   56篇
肿瘤学   3523篇
  2024年   92篇
  2023年   220篇
  2022年   349篇
  2021年   676篇
  2020年   410篇
  2019年   583篇
  2018年   638篇
  2017年   510篇
  2016年   613篇
  2015年   638篇
  2014年   812篇
  2013年   1015篇
  2012年   1715篇
  2011年   1883篇
  2010年   1026篇
  2009年   899篇
  2008年   1709篇
  2007年   1891篇
  2006年   1778篇
  2005年   1924篇
  2004年   1828篇
  2003年   1850篇
  2002年   1691篇
  2001年   746篇
  2000年   690篇
  1999年   686篇
  1998年   422篇
  1997年   361篇
  1996年   313篇
  1995年   288篇
  1994年   243篇
  1993年   221篇
  1992年   456篇
  1991年   425篇
  1990年   388篇
  1989年   406篇
  1988年   359篇
  1987年   361篇
  1986年   320篇
  1985年   331篇
  1984年   217篇
  1983年   191篇
  1982年   109篇
  1981年   101篇
  1980年   84篇
  1979年   159篇
  1978年   91篇
  1975年   79篇
  1974年   83篇
  1973年   93篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Brodie bite is a comparatively rare type of malocclusion found in primary and mixed dentition. It not only adversely affects chewing and muscle functions, but also impairs normal growth and development of the mandible. This report describes the therapeutic results of a patient with bilateral Brodie bite in early mixed dentition after using a bonded constriction quad-helix appliance. The patient, a boy aged 9 years and 2 months, first visited our hospital after occlusal abnormality in the molar region was detected at a local dental clinic. Case analysis resulted in a diagnosis of bilateral Brodie bite with slight mandibular retrognathism. Treatment objectives were to reduce the arch width of the maxillary dentition and expand the mandibular arch in order to establish and stabilize molar occlusion and to achieve a Class I molar relation and appropriate overbite and overjet. Treatment comprised covering the occlusal surface of the maxillary molars with resin and attaching a bonded constriction quad-helix appliance joined with a 0.040-inch quad-helix wire. A bi-helix appliance was also fixed to the mandibular dentition. Brodie bite visibly improved after 5 months. Cervical headgear was then fitted and the patient observed until eruption of the permanent dentition was complete. Class I molar relation was achieved after 2 years and 6 months, although spacing remained in the maxillary and mandibular dentitions. Treatment of bilateral Brodie bite in mixed dentition by means of a bonded constriction quad-helix appliance attached to the maxillary dentition enabled effective bite opening and reduction in the width of maxillary arch independent of the patient's cooperation, providing good therapeutic outcome in a short time period.  相似文献   
42.
A backward distraction osteogenesis (BDO) of the condylar segment for treatment of mandibular ramus deficiency was developed. This report describes the clinical progress of a patient with mandibular ramus deficiency in whom satisfactory occlusion was achieved and maintained by gradual posterosuperior repositioning of the displaced condyles into the glenoid fossae during intermaxillary fixation. Findings of pre- and postoperative clinical and magnetic resonance imaging indicate that the effect of BDO on the temporomandibular joint was negligible.  相似文献   
43.
44.
45.
46.
47.
Exposure of cultured endothelium to environments with low concentrations of oxygen, in the range of those observed in pathophysiologic hypoxemic states in vivo, compromises cellular barrier and coagulant function. An atmosphere with PO2 approximately 14 mm Hg was not lethally toxic to endothelial cultures, but cells became larger and exhibited small intercellular gaps. At low oxygen concentrations, passage of macromolecular tracers through hypoxic endothelial monolayers was accelerated in a time- and dose-dependent manner, presumably by a paracellular pathway via the gaps. Cell surface coagulant properties of the endothelium were also perturbed. At PO2 approximately 14 mm Hg thrombomodulin antigen and functional activity on the cell surface were diminished by 80-90%, and Northern blots demonstrated suppression of thrombomodulin mRNA. The decrease in thrombomodulin was twice as great compared with the general decline in total protein synthesis in hypoxia. In addition, expression of a direct Factor X activator developed under hypoxic conditions; the activator was membrane-associated and expressed on the surface of intact cultures, Ca-dependent, inhibited by HgCl2 but not PMSF, and had Km approximately 25 micrograms/ml for the substrate at pH 7.4. Synthesis of the activator was blocked by inclusion of cycloheximide, but not warfarin, in the culture medium. These results demonstrate that endothelial function is perturbed in a selective manner in the presence of low concentrations of oxygen, providing insights into mechanisms which may contribute to vascular dysfunction in hypoxemic states.  相似文献   
48.

Purpose

Long-term dialysis often causes physiological and metabolic problems that may affect the outcomes of surgery. The aim of this study was to elucidate whether emergency surgery for acute abdomen yields similar outcomes in dialysis patients versus non-dialysis patients.

Methods

The subjects were 126 patients who underwent emergency surgery for acute abdomen between January, 2007 and November, 2011 in our hospital. They were divided into a dialysis group (HD group; n = 9) and a non-dialysis group (non-HD group; n = 117) and their postoperative morbidity and mortality were compared.

Results

Postoperative morbidity and mortality were significantly worse in the HD group. All 9 of these patients succumbed to postoperative complications versus only 5 of the 117 patients in the non-HD group.

Conclusion

The outcomes of emergency surgery for acute abdomen were significantly worse for dialysis patients than for non-dialysis patients. Prompt diagnosis, initiation of the most suitable surgical procedure, and meticulous postoperative cares are imperative to improving the surgical outcomes of dialysis patients.  相似文献   
49.
Desmoid tumors are benign fibroblastic neoplasms with no metastatic potential, but a propensity for local recurrence even after complete surgical resection. These lesions can develop at any site in the body, and commonly occur in the intra-abdominal area. Intra-abdominal desmoid tumors usually occur at the mesentery or retroperitoneum, and may morphologically mimic gastrointestinal stromal tumors (GISTs). Distinguishing between these tumors is important, because the therapies differ substantially, but is often difficult even with the use of CD117 staining. We herein report the cases of two patients with sporadic intra-abdominal desmoid tumors that were differentiated from GIST by immunohistological examination using beta-catenin and CD34. Desmoid tumors specifically express nuclear beta-catenin, and show no expression of CD34. We recommend staining for beta-catenin and CD34 when an intra-abdominal desmoid tumor is suspected.  相似文献   
50.

Purpose

We assessed the incidence of coronary artery disease (CAD) during hospitalization after emergency surgery for a type A acute aortic dissection.

Methods

A total of 123 patients underwent multi-slice computed tomography (MSCT) scans during an early stage after surgery. The patients were divided into two groups: group I consisted of 14 patients (11.4 %) who had coronary artery stenosis of more than 75 % on MSCT, and group II consisted of 109 patients (88.6 %) who had no coronary lesions.

Results

The prevalence of diabetes, dyslipidemia and a smoking history was significantly higher in group I. Although the serum low-density lipoprotein cholesterol levels were similar, the high-density lipoprotein cholesterol (HDL) level was significantly lower in group I (36.4 ± 7.9 mg/dl) than in group II (49.6 ± 13.5 mg/dl, P = 0.0005). The maximum carotid intima-media thickness (IMT) was significantly thicker in group I (1.17 ± 0.37 mm) compared to group II (0.96 ± 0.33 mm, P = 0.0297). The logistic regression analysis detected that a carotid IMT over 1.1 mm (odds ratio 4.35, P = 0.0371) and HDL less than 40 mg/dl (odds ratio 3.90, P = 0.0482) were predictors for CAD.

Conclusions

CAD screening should be recommended for patients with aortic dissection who have several atherosclerosis risk factors, even after emergency surgery.  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