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   2619篇
  免费   245篇
  国内免费   14篇
耳鼻咽喉   8篇
儿科学   113篇
妇产科学   31篇
基础医学   307篇
口腔科学   52篇
临床医学   318篇
内科学   515篇
皮肤病学   48篇
神经病学   244篇
特种医学   356篇
外科学   307篇
综合类   62篇
预防医学   211篇
眼科学   38篇
药学   119篇
肿瘤学   149篇
  2021年   27篇
  2020年   25篇
  2019年   34篇
  2018年   41篇
  2017年   17篇
  2016年   33篇
  2015年   43篇
  2014年   62篇
  2013年   66篇
  2012年   98篇
  2011年   89篇
  2010年   59篇
  2009年   63篇
  2008年   58篇
  2007年   88篇
  2006年   68篇
  2005年   81篇
  2004年   70篇
  2003年   56篇
  2002年   65篇
  2001年   55篇
  2000年   55篇
  1999年   83篇
  1998年   104篇
  1997年   80篇
  1996年   90篇
  1995年   69篇
  1994年   62篇
  1993年   73篇
  1992年   41篇
  1991年   39篇
  1990年   47篇
  1989年   82篇
  1988年   51篇
  1987年   69篇
  1986年   60篇
  1985年   67篇
  1984年   44篇
  1983年   35篇
  1982年   42篇
  1981年   37篇
  1980年   41篇
  1979年   19篇
  1978年   32篇
  1977年   37篇
  1976年   38篇
  1975年   29篇
  1972年   16篇
  1971年   25篇
  1968年   17篇
排序方式: 共有2878条查询结果,搜索用时 15 毫秒
1.
Eleven children with Pseudomonas aeruginosa infection complicating foot puncture wounds were reviewed. Delay in presentation (mean 2 days) and diagnosis (mean 9 days) due to a paucity of clinical signs of deep infection was characteristic of this condition. Septic arthritis (5 patients) and osteomyelitis (3 patients) were frequent complications. Treatment involved multiple surgical debridements and prolonged intravenous antibiotic therapy. The clinical outcome was good although long-term radiographic changes were common.  相似文献   
2.
Five out of 12 physically healthy patients with depression undergoing a tyramine pressor test developed cardiac arrhythmias. These arrhythmias occurred in drug-free patients in three out of 12 infusions following as little as 0.03 mg/kg of tyramine and after moclobemide, a reversible inhibitor of monoamine oxidase-A, in four out of 14 tyramine infusions with as little as 0.04 mg/kg of tyramine. The arrhythmias seen were independent of patient's age and occurred both before and after 30 mmHg elevations in systolic blood pressure. Electrocardiographic abnormalities and arrhythmias seen were a loss of p waves, sinus tachycardia, frequent atrial ectopic beats, atrial premature beats, Wenckebach phenomenon, junctional rhythm, ventricular ectopics, varying QRS configurations, and ventricular bigeminy. Tyramine, both oral and intravenous, caused similar reproducible changes in dogs, though not in rats, mice or guinea pigs. Practical implications are that tyramine pressor testing in humans should be performed cautiously and only with adequate cardiac monitoring and resuscitation facilities at hand. These findings suggest that a normal dietary component can induce serious cardiac arrhythmias, and that a low-tyramine diet may be of value for patients who are susceptible to cardiac arrhythmias.  相似文献   
3.
A vertically integrated health care system is an arrangement whereby a health care organization offers, either directly or through others, a broad range of patient care and support services. This article discusses the market forces and strategic considerations driving the recent trend toward vertical linkages in health care markets and examines some of the managerial implications and issues associated with this vertical restructuring trend.  相似文献   
4.
The axon terminals of cone horizontal cells in the goldfish retina form typical chemical synaptic contacts in the middle of the inner nuclear layer. Approximately 60% of the identified postsynaptic elements were perikarya, axons and dendrites of bipolar cells. The other identified postsynaptic elements were perikarya and processes of interplexiform cells. We propose that the horizontal cell axon terminal contribute to the antagonistic surround responses of the bipolar cells and that they modulate inputs to the outer plexiform layer conveyed by interplexiform cells. Output synapses from horizontal cell axons to unidentified neuronal processes as well as occasional input synapses to the axons from interplexiform cell processes and unidentified perikarya were also observed in the same region of the inner nuclear layer.  相似文献   
5.
Advances in endoscopic surgical equipment and laser technology have expanded the role of thoracoscopy to include thoracoscopic pulmonary resection. Eighty-five thoracoscopic pulmonary resections were performed on 61 consecutive patients with small lesions (less than 3 cm) in the outer third of the lung. Patients with preoperative histologic evidence of bronchogenic carcinoma were excluded unless there was impairment of cardiopulmonary function, advanced age, or concomitant extrathoracic malignancy. These thoracoscopic pulmonary resections were accomplished with the neodymium:yttrium-aluminum garnet laser (31), endoscopic stapler (29), or both (25). The mean diameter of the lesions was 1.3 cm (range, 0.4 to 2.7 cm). There has been one late death (38th postoperative day) unrelated to the operation. Morbidity consisted of postoperative atelectasis (2), pneumonia (2), bleeding requiring transfusion (1), and bronchopleural fistula of greater than 7 days duration (3). There were no wound problems. The mean period of chest tube drainage was 3.3 +/- 3.0 days. Mean postoperative stay was 5.7 +/- 4.9 days. The pathologic diagnosis was benign disease in 28 patients (interstitial fibrosis/pneumonitis, 15; radiation fibrosis, 1; sclerosing hemangioma, 1; rheumatoid nodules, 1; granuloma, 2; nocardia, 1; infarct, 1; hamartoma, 4; scar, 1; cytomegalovirus pneumonia, 1), metastatic malignancy in 20 patients, and bronchogenic carcinoma in 13 patients. Five patients found at thoracoscopic pulmonary resection to have bronchogenic cancer had adequate pulmonary function and therefore underwent formal segmentectomy (3) or lobectomy (2). Thoracoscopic pulmonary resection was the only operation performed on patients with benign disease, patients with metastatic lesions, and selected patients with limited stage bronchogenic carcinoma at increased risk for thoracotomy.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
6.
7.
Video-assisted thoracic surgery is emerging as a viable approach to a number of intrathoracic disorders. Technical difficulties related to improper instrument selection and suboptimal intercostal operative access can reduce the utility of, and the enthusiasm for, the video-assisted thoracic surgical approach. This report describes the intercostal access strategy and the instrument positioning that we now prescribe for many video-assisted thoracic surgical procedures. These approaches have become refined during the course of our experience with 467 patients undergoing video-assisted thoracic operations over the last 18 months.  相似文献   
8.
9.
10.
Several molecules, such as growth factors and neurotrophic factors, are required both for the differentiation of specific retinal cell types and the long-term cell survival of all retinal neurons. As diffusible factors, these molecules act non-cell-autonomously. Here, we describe the loss of function phenotype for dazed (dzd), a gene that acts cell-autonomously for retinal cell survival and affects the differentiation of rod photoreceptors and the Muller glia. By 3 days after fertilization, dazed mutant embryos have small eyes and slight heart edema. Acridine orange staining indicated a significant degree of retinal cell death occurring by 48 hr after fertilization, and histological analysis revealed that dying cells were found in the inner and outer nuclear layers and near the marginal zones. Although molecular and morphological differentiation of the inner retina and cone photoreceptors occurred, rod photoreceptors failed to differentiate beyond a small patch in the ventral retina and rod precursors failed to respond to exogenously added retinoic acid, which normally potentiated rod differentiation. Mosaic analysis indicated that the dazed gene acts cell-autonomously for rod production and cell survival, as dazed clones failed to produce rods outside the ventral patch and dazed cells were not maintained in wild-type hosts. Raising mutants under constant light resulted in severe retinal degeneration, whereas raising embryos under constant darkness did not provide any additional protection from cell death. Behavioral analysis showed that a subpopulation of adult fish that were heterozygous for the dazed mutation had elevated visual thresholds and were night blind, suggesting that dazed may also be required for long-term dim-light vision. Taken together, our studies suggest a role for the dazed gene in rod and Muller cell development and overall retinal cell survival and maintenance.  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