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   7348篇
  免费   703篇
  国内免费   22篇
耳鼻咽喉   109篇
儿科学   247篇
妇产科学   179篇
基础医学   983篇
口腔科学   138篇
临床医学   732篇
内科学   1458篇
皮肤病学   90篇
神经病学   774篇
特种医学   497篇
外科学   966篇
综合类   140篇
一般理论   5篇
预防医学   704篇
眼科学   42篇
药学   426篇
中国医学   1篇
肿瘤学   582篇
  2021年   108篇
  2019年   94篇
  2018年   100篇
  2017年   84篇
  2016年   101篇
  2015年   102篇
  2014年   165篇
  2013年   211篇
  2012年   298篇
  2011年   312篇
  2010年   198篇
  2009年   188篇
  2008年   307篇
  2007年   345篇
  2006年   290篇
  2005年   313篇
  2004年   291篇
  2003年   279篇
  2002年   256篇
  2001年   252篇
  2000年   248篇
  1999年   244篇
  1998年   88篇
  1997年   95篇
  1996年   93篇
  1995年   75篇
  1994年   61篇
  1992年   144篇
  1991年   176篇
  1990年   193篇
  1989年   191篇
  1988年   153篇
  1987年   158篇
  1986年   136篇
  1985年   157篇
  1984年   113篇
  1983年   101篇
  1982年   71篇
  1981年   67篇
  1980年   59篇
  1979年   89篇
  1978年   70篇
  1977年   69篇
  1976年   67篇
  1975年   66篇
  1974年   78篇
  1973年   74篇
  1972年   67篇
  1971年   61篇
  1969年   65篇
排序方式: 共有8073条查询结果,搜索用时 15 毫秒
991.
Chondromalacia patellae: assessment with MR imaging   总被引:10,自引:0,他引:10  
Magnetic resonance (MR) images of the posterior patellar hyaline articular cartilage were obtained in 23 subjects to determine if MR imaging could accurately demonstrate the patellar cartilage. Arthroscopy was used as the standard of reference. Three subjects were asymptomatic volunteers. In the remaining 20 who had patellofemoral pain, arthroscopy was performed before MR imaging in seven and afterward in 12; one did not undergo arthroscopy. MR imaging showed focal areas of swelling of the patellar cartilage, focal hypointensity, surface irregularity, areas of thinning, and areas of cartilage loss with exposure of subchondral bone. The surgical findings agreed with those from MR images in all seven patients who underwent arthroscopy before MR imaging and in ten of the 12 who underwent surgery afterward. MR imaging is an accurate means of examining the posterior patellar cartilage and should be considered as an alternative to diagnostic arthroscopy when chondromalacia patellae is suspected.  相似文献   
992.
1. Injuries of the abdominal aorta in dogs may be corrected with subsequent perfect restoration of the continuity of the vessel. 2. The complete occlusion of the aorta for a period of 30 minutes is not necessarily followed by serious consequences. 3. In cases in which a portion of the aorta must be resected, an arterial segment taken from another animal can be safely utilized as a transplant. 4. While the reestablishment of the continuity of the severed aorta by the circular suture is possible, the approximation of the severed ends during the suture entails such injury that thrombosis frequently occurs. Therefore, when the aorta is completely severed, the introduction of a transplanted segment is indicated. 5. An arterial tube of increased caliber made of smaller vessels such as the carotid lends itself readily as a transplant to the severed aorta, with a reasonable assurance of reestablishing the continuity of this vessel. 6. Defects in the aorta can be readily corrected by the use of fascial transplants with a minimum danger of thrombosis.  相似文献   
993.
We report four previously undescribed primary giant cell tumors of the extrahepatic biliary tree and morphologically compare them with 10 anaplastic spindle and giant cell carcinomas with osteoclast-like giant cells of the gallbladder. Two giant cell tumors were located in the distal common bile duct; one in the cystic duct and one in the gallbladder. The 3 patients with bile duct tumors were male, and the only patient with a gallbladder tumor was a female. The age of the patients ranged from 45 to 60 years with an average of 55 years. The patients with bile duct tumors presented with biliary obstruction, and the patient with a gallbladder tumor presented with symptoms of cholelithiasis and a gallbladder mass. Histologically, the tumors were similar to giant cell tumors of bone. They consisted of a mixture of mononuclear and multinucleated osteoclast-like giant cells. The mononuclear cells showed no atypical features, and their nuclei were similar to those of the multinucleated giant cells. CD163 immunoreactivity was restricted to the mononuclear cells, whereas CD68 and HAM 56 labeled only the multinucleated osteoclast-like giant cells. The mononuclear cells were EMA-positive but did not express cytokeratins. Follow-up showed that 3 patients were alive and disease-free 3.7 to 7 years after surgery. The anaplastic spindle and giant cell carcinomas contained a fewer number of osteoclast-like giant cells, and their mononuclear cells showed considerable variation in size and shape, marked cytologic atypia, and numerous mitotic figures. They were focally cytokeratin positive (AE1/AE3; CAM 5.2) and did not label with CD163, CD68, and HAM 56. The benign osteoclast-like giant cells showed immunoreactivity for CD68 and HAM 56 but were negative for CD163 and cytokeratins. Giant cell tumors of the extrahepatic biliary tree are benign true histiocytic neoplasms that should be distinguished from the highly lethal anaplastic spindle and giant cell carcinomas with osteoclast-like giant cells by detailed cytologic analysis and immunohistochemical stains for CD163, CD68, HAM 56, and cytokeratins.  相似文献   
994.
Potential or actual supraglottic airway obstruction becomes critical when general anesthesia is begun. Four cases illustrated such obstruction, and the anesthetic and surgical management of each condition was critical. In carcinoma of the supraglottic larynx and in pharyngeal abscess, the unobstructed airway in the conscious patient became impossible to secure once general anesthesia was begun. Unappreciated pathological deformity prohibited endotracheal intubation, and anesthesia precipitated obstruction. In epiglottitis and peritonsillar abscess, the nature of the impending airway obstruction was appreciated, and the selection of a safe technique to secure the airway was made. Anesthetic and surgical management of potential supraglottic obstruction includes five options: (1) oral tracheal intubation by laryngoscopy while the patient is awake; (2) awake nasotracheal intubation; (3) inhalation induction by general anesthesia with intubation; (4) rapid induction with barbiturates and muscle relaxants with intubation; and (5) tracheostomy with local anesthesia.  相似文献   
995.
The Film Digital Radiography System (FilmDRS) is a device with a laser optical film digitizer, 2,000 X 2,000 X 12-bit memory, and a 1,000-line video display. To evaluate the adequacy of this device for general radiography of the chest, four readers independently analyzed both radiographs and the corresponding video display of the digitized chest images of 150 patients, consisting of 100 images of abnormalities and 50 normal images. The overall results indicate equal sensitivity for the two systems. The FilmDRS, with interactive windowing, proved superior in the detection of hilar and mediastinal disease. X-ray film was superior in allowing detection of hyperlucent states. There was equivalent sensitivity for other disease categories. Superior specificity was achieved with conventional radiographs.  相似文献   
996.
997.
Ten patients with advanced squamous cell carcinoma of the uterine cervix received induction chemotherapy with cis-platinum, mitomycin-C, vincristine, and bleomycin (BOMP) over a 5 week period, followed by radiotherapy with concomitant weekly cisplatinum. Two patients were FIGO stage I-B barrel-shaped, five were stage II-B, and three were III-B. All patients responded to induction chemotherapy with five complete and five partial responses. At the completion of radiation therapy, nine patients had negative biopsies. One patient never reached a complete response and died of distant metastasis. Another underwent total exenteration for a central recurrence and was found to have microscopic paraaortic lymph node involvement. A third recurred in the parametrium. Two patients with barrel-shaped tumors underwent extrafascial hysterectomies; both had negative specimens and tolerated surgery well. Although follow-up is short, this new approach for advanced carcinoma of the cervix yielded excellent results and was well tolerated.  相似文献   
998.
Summary Twelve surface replacement arthroplasties were performed on the hips of ten mongrel dogs using scaled-down replicas of the Wagner prosthesis. The contralateral hips and two further animals served as nonoperated controls. Animals were killed 5 months postoperatively. Clinical, radiological, histological and fluorochrome-labelling studies were employed to assess the bony and soft tissue reaction to resurfacing arthroplasty. There was no clinical or radiographic evidence of prosthetic loosening. Histological examination disclosed a thick foreign body and chronic inflammatory membrane containing acrylic cement and polyethylene wear particles at the bone-cement interface of both components. Generally, the bone marrow and trabecula were viable. There was evidence of increased bony remodelling and new bone formation in the subchondral area. The similarity between the above findings and those of aseptic component loosening in man suggests a mechanism whereby wear debris initiate a biological foreign body reaction culminating in component loosening.  相似文献   
999.
Having previously confirmed a lower developmental quotient (DQ) in very-low-birth-weight infants identified by physiotherapists as being at risk, a retrospective analysis was undertaken to ascertain which of the neurodevelopmental tests were of value in predicting subsequent poor outcome. At 3 months corrected age, 9 tests differentiated normal from at-risk infants, and infants with abnormal test results were assessed as having a 56% (mean) risk of subsequent DQ less than 100. At the 6-month assessment, 7 neurodevelopmental tests differentiated normal from at-risk infants; infants with abnormal test results had a 73% (mean) risk of subsequent DQ less than 100. At 12 months, 3 tests differentiated normal from at-risk infants; infants with abnormal test results had a 79% (mean) risk of DQ less than 100. We believe the identification of predictive tests may assist doctors and developmental therapists in assessing need for intervention and response to treatment in high-risk infants. However, it must be noted that the tests studied relate to DQ at 1 year; we are not yet in a position to comment on the relationship between 1 year DQ and subsequent neurodevelopmental outcome.  相似文献   
1000.
Seven cases of lipomatous masses within the liver parenchyma were demonstrated with computed tomography (CT). Five of these cases were obtained from a retrospective review of 50 cases of renal angiomyolipoma in which the liver was adequately demonstrated. The other two cases were from the files of the Armed Forces Institute of Pathology and had no associated renal lesions. Three of the five cases were associated with tuberous sclerosis. In all seven cases, the fatty tumors appeared on CT scans as a well-defined, 0.8-13-cm mass, with attenuation coefficients of less than -30 HU. On ultrasound studies, the lesions were well circumscribed, highly echogenic, and similar to hemangiomas. While distinctly rare lesions, these lipomatous masses are not as unusual as the literature would indicate. One may anticipate such masses in patients with renal angiomyolipomas and in a relatively high percentage of those with tuberous sclerosis.  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