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   16976篇
  免费   1100篇
  国内免费   78篇
耳鼻咽喉   127篇
儿科学   389篇
妇产科学   352篇
基础医学   2160篇
口腔科学   365篇
临床医学   1641篇
内科学   3245篇
皮肤病学   214篇
神经病学   1647篇
特种医学   649篇
外科学   2660篇
综合类   191篇
现状与发展   1篇
一般理论   30篇
预防医学   1531篇
眼科学   531篇
药学   1277篇
中国医学   25篇
肿瘤学   1119篇
  2023年   147篇
  2022年   300篇
  2021年   645篇
  2020年   319篇
  2019年   482篇
  2018年   558篇
  2017年   405篇
  2016年   420篇
  2015年   521篇
  2014年   694篇
  2013年   838篇
  2012年   1352篇
  2011年   1308篇
  2010年   720篇
  2009年   666篇
  2008年   1061篇
  2007年   1073篇
  2006年   1010篇
  2005年   1008篇
  2004年   862篇
  2003年   800篇
  2002年   720篇
  2001年   159篇
  2000年   117篇
  1999年   135篇
  1998年   142篇
  1997年   107篇
  1996年   93篇
  1995年   81篇
  1994年   69篇
  1993年   56篇
  1992年   75篇
  1991年   76篇
  1990年   73篇
  1989年   82篇
  1988年   60篇
  1987年   60篇
  1986年   56篇
  1985年   43篇
  1984年   59篇
  1983年   46篇
  1982年   39篇
  1981年   49篇
  1980年   35篇
  1979年   29篇
  1978年   33篇
  1977年   30篇
  1976年   41篇
  1975年   28篇
  1974年   31篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Performance of same-day upper and lower endoscopy has many potential advantages, as it may reduce costs, shorten hospital stay, and expedite patient care, but its feasibility, efficacy, and potential have not been carefully defined. We report here our experience with a group of 87 patients who underwent same-day upper and lower endoscopy (174 procedures) over a 2-yr period at a tertiary care VA Hospital, compared with an alternate-day upper and lower endoscopy group of 50 patients (100 procedures) over the same time period. Most patients were elderly males. Common indications for endoscopy were occult or overt gastrointestinal bleeding, previous or concomitant history of pertinent pathology (i.e., polyps, ulcers), abdominal pain, diarrhea, or other symptoms, abnormal radiological studies, and iron deficiency anemia. Both groups required similar amounts of intravenous sedation. There were no complications in either group. In both groups, common positive findings were inflammation (i.e., colitis, esophagitis), benign neoplasms, diverticulae, peptic ulcer, and cancer. In both groups, only 2-6% had negative upper and lower endoscopy, whereas either one procedure was negative in 25% and 18% of cases, respectively. We conclude that the practice of same-day inpatient upper and lower endoscopy is feasible, has excellent diagnostic yield, even in the elderly, and carries no increased risks. When indicated, the practice of same-day upper and lower endoscopy should be encouraged.  相似文献   
22.
A case of a primary malignant mesenchymoma of the lung with elements of rhabdomyo-, leiomyo-, osteo-, fibro- and lipo-sarcoma is described. The tumor developed in a man of 58 with a long history of smoking, complaints of chest pains and cough with scanty sputum expectoration. The neoplastic process involved the upper lobe of the left lung and microscopically contained smooth muscle, endothelial, fibroblast-like cells, multinuclear giant cells resembling osteoclasts, strips of osteoid-like hyalinized connective tissue. Electron-microscopic examination revealed myoid-type cells with clusters of myofilaments and Z-type material, cells resembling fibroblasts, osteoclasts and lipocytes. It is suggested that there should be a common histogenesis of primary lung sarcomas arising from a stem cell precursor of mesenchymal origin in lung stroma, bronchial and vascular walls, pleura.  相似文献   
23.
24.
The utility of MRI using magnetization transfer (MT) enhanced pulse sequences to diagnose hepatic cirrhosis in a rat model was investigated. Hepatic T1 was measured with and without MT off-resonance RF pulses in 17 treated and six control rats. The livers were evaluated histologically, and the hydroxyproline content quantitatively measured. We did not find a statistically significant linear correlation between the MR relaxation times and the degree of tissue injury. However, the MR measurements performed with MT were superior to those without differentiating the treated and control groups. Specifically, the T1 times were 695 ±76 ms for the treated group, versus 748 ± 61 ms in the controls; P= 0.095. The T1sat times were also lower in the treated group, with statistical significance: 367 ± 51 ms versus 421 ± 38 ms, P = 0.016. Finally, the change in the relaxation rates (the inverse of the relaxation times) with and without saturation were 1.31 ± 0.22 s?1 (treated group) versus 1.05 ± 0.12 s?1 (controls), which differed significantly, P= 0.001.  相似文献   
25.
Our recent report that fructose supported the metabolism of some, but not all axons, in the adult mouse optic nerve prompted us to investigate in detail fructose metabolism in this tissue, a typical central white matter tract, as these data imply efficient fructose metabolism in the central nervous system (CNS). In artificial cerebrospinal fluid containing 10 mmol/L glucose or 20 mmol/L fructose, the stimulus-evoked compound action potential (CAP) recorded from the optic nerve consisted of three stable peaks. Replacing 10 mmol/L glucose with 10 mmol/L fructose, however, caused delayed loss of the 1st CAP peak (the 2nd and 3rd CAP peaks were unaffected). Glycogen-derived metabolic substrate(s) temporarily sustained the 1st CAP peak in 10 mmol/L fructose, as depletion of tissue glycogen by a prior period of aglycaemia or high-frequency CAP discharge rendered fructose incapable of supporting the 1st CAP peak. Enzyme assays showed the presence of both hexokinase and fructokinase (both of which can phosphorylate fructose) in the optic nerve. In contrast, only hexokinase was expressed in cerebral cortex. Hexokinase in optic nerve had low affinity and low capacity with fructose as substrate, whereas fructokinase displayed high affinity and high capacity for fructose. These findings suggest an explanation for the curious fact that the fast conducting axons comprising the 1st peak of the CAP are not supported in 10 mmol/L fructose medium; these axons probably do not express fructokinase, a requirement for efficient fructose metabolism.  相似文献   
26.
The Distally Based Sural Artery Flap for Ankle and Foot Coverage   总被引:1,自引:0,他引:1  
The sural artery flap is a distally based fasciocutaneous flap that has many advantages to offer for coverage in the foot and ankle area. It has the largest arc of rotation of all the regional flaps and does not require sacrifice of any major artery, and moderate-to-large-sized defects can be covered adequately. The dissection technique is simple, and donor site morbidity is minimal. We report our experience with 17 cases. Age range was from 13 to 56 years. Ten (59%) defects were posttraumatic, 3 (17%) were related to reconstructive surgery of the foot or tendon Achilles', 2 (11%) resulted from tumor resection, and 1 each were from infection and gunshot wound. The smallest flap was 6 x 4 cm and the largest was 15 x 12 cm, with the average size being 11 x 7.5 cm. In 5 cases, the donor site was closed primarily, and in other cases, split-thickness skin graft was needed. The short saphenous vein was included in the pedicle in all cases. There was no incidence of complete flap necrosis. Follow-up ranged from 3 to 30 months. Two cases (12%) developed partial superficial necrosis. In 1 case, there was partial wound dehiscence that needed debridement and repair. Another case had postoperative discharge, which subsided after removal of the calcaneal plate. None of the patients complained of any functional problem related to loss of sensation along the lateral border of the foot. The sural island flap is a reliable, safe, and easy method of providing soft tissue coverage in the area of the foot and ankle.  相似文献   
27.
28.
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