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   1077025篇
  免费   71732篇
  国内免费   1369篇
耳鼻咽喉   15038篇
儿科学   34753篇
妇产科学   28784篇
基础医学   153688篇
口腔科学   29633篇
临床医学   95114篇
内科学   203978篇
皮肤病学   24406篇
神经病学   81556篇
特种医学   43024篇
外国民族医学   201篇
外科学   163328篇
综合类   21768篇
现状与发展   1篇
一般理论   266篇
预防医学   74913篇
眼科学   24543篇
药学   86243篇
  7篇
中国医学   2805篇
肿瘤学   66077篇
  2019年   7778篇
  2018年   11318篇
  2017年   8919篇
  2016年   10117篇
  2015年   11298篇
  2014年   15303篇
  2013年   22258篇
  2012年   30621篇
  2011年   32374篇
  2010年   19002篇
  2009年   17867篇
  2008年   30048篇
  2007年   32150篇
  2006年   32785篇
  2005年   31111篇
  2004年   29823篇
  2003年   28650篇
  2002年   27596篇
  2001年   60094篇
  2000年   61553篇
  1999年   50984篇
  1998年   12461篇
  1997年   11028篇
  1996年   11035篇
  1995年   10341篇
  1994年   9356篇
  1993年   8872篇
  1992年   37822篇
  1991年   36315篇
  1990年   35787篇
  1989年   34324篇
  1988年   30916篇
  1987年   30023篇
  1986年   28255篇
  1985年   26494篇
  1984年   19222篇
  1983年   16137篇
  1982年   8843篇
  1979年   17054篇
  1978年   11427篇
  1977年   10244篇
  1976年   8859篇
  1975年   10084篇
  1974年   11669篇
  1973年   11294篇
  1972年   10777篇
  1971年   10107篇
  1970年   9273篇
  1969年   8964篇
  1968年   7935篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
991.
992.
993.
Anorexia nervosa (AN) can cause both functional and structural cardiac complications, including a variety of different conduction abnormalities. This is the first case report of symptomatic diurnal second‐degree atrioventricular (AV) block (Mobitz Type I) in an adolescent with AN. We present a 12‐year‐old girl with AN, restrictor sub‐type who reported cardiac symptoms during weight gain, at the time of the initial diagnosis of AV block. Second‐degree AV block (Mobitz Type I) is discussed as a possible complication of the AN, as well as being an intrinsic conduction system disease. © 2009 by Wiley Periodicals, Inc. Int J Eat Disord 2009  相似文献   
994.
Serial electrocardiographic examinations were made in fifty cases of typhoid fever. In thirty-five cases, deviations from the normal were observed. The alterations were mainly present in the T waves, which became flat, isoelectric, or diphasic, usually after defervescence. Twenty-three patients with T-wave changes were given niacin which resulted in rapid normalization of the electrocardiogram. In twelve cases with pathologic electrocardiograms, a spontaneous gradual return to normal was observed.The rapid effect of niacin and the development of the electrocardiographic changes concomitant with reduced niacin excretion in the urine is considered as evidence that the described electrocardiographic abnormalities are due to niacin deficiency.  相似文献   
995.
996.
997.
Brain cyclooxygenases (COX), the rate-limiting enzyme in prostaglandin synthesis, is rapidly and transiently induced by convulsions in hippocampal and cortical neurons. Previous studies have explored the protective effect of naproxen (non-selective COX-inhibitor) or rofecoxib (selective COX-2 inhibitor) against chemical kindling in mice. With this background, the present study was designed to explore the possible effect of nimesulide (a preferential COX-2 inhibitor) against pentylenetetrazol (PTZ)-induced kindling epilepsy in mice. To induce kindling, PTZ was injected in a subconvulsive dose (40 mg/kg, i.p.) every other day for 15 days. Nimesulide (2.5 or 5 mg/kg, p.o.) was administered each day 45 min before either PTZ or vehicle challenge. The intensity of kindling was assessed immediately after PTZ administration according to a prevalidated scoring scale. On 16th day i.e. 24 h after the last dose of PTZ, animals were sacrificed and various biochemical parameters were assessed in the whole brain. Compared with normal control group, PTZ-kindled mice had significantly higher levels of malondialdehyde, nitrite, myeloperoxidase but had lower levels of reduced glutathione in the whole brain homogenate. Chronic treatment with nimesulide (2.5 or 5 mg/kg, p.o.) for 15 days showed significant decrease in kindling score and could play a role in controlling the accompanying biochemical alterations due to PTZ. These results suggested that nimesulide, a preferential COX-2 inhibitor offered neuroprotection against PTZ-induced kindling in mice.  相似文献   
998.
OBJECTIVE: To estimate medium-term success after a technique for ultrasound-guided sclerotherapy for superficial chronic venous disease. DESIGN: A prospective study in a single unit with ultrasound surveillance after treatment. MATERIALS: Results after 1189 treatment sessions for 807 venous saphenous veins and related tributaries or non-saphenous tributaries in 489 patients. METHODS: Univariate life table analysis determined primary and secondary success rates. Multivariate Cox regression analysis detected covariates that affected outcome. RESULTS: Primary and secondary success rates at 36 months for all veins were 52.4% (95%CI 46-58%) and 76.8% (95%CI 71-82%). Cox regression analysis for primary success for all veins showed significantly worse results for saphenous veins compared to tributaries (HR 3.72 - 95%CI 1.9 to 7.3). Cox regression for all saphenous veins showed independently worse results for patients less than 40 years age (HR 2.16 - 95%CI 1.27-3.66), small compared to great saphenous veins (HR 1.58 - 95%CI 1.11-2.24), veins greater than 6mm diameter compared to smaller veins (HR 2.22 - 95%CI 1.40-3.50), liquid compared to foam sclerotherapy (HR 2.20 - 95%CI 1.28-3.78), lower volumes of sclerosant compared to volumes greater than 12 ml (HR 0.51 - 95%CI 0.33-0.81) and highly diluted compared to concentrated sclerosant (HR 2.05 - 95%CI 1.21-3.46) with worse results using highly diluted or undiluted 3% sclerosant compared to a 1.5% concentration. There were no significant differences for primary success for saphenous veins for date of procedure, sex, side, primary or recurrent varicose veins, or commercial type of sclerosant. CONCLUSIONS: Ultrasound-guided sclerotherapy gives satisfactory results if it is accepted that treatment may need to be repeated to achieve secondary success. Results provide a basis for further research to explore factors that might affect outcome. Younger patients with larger diameter saphenous veins may warrant alternative forms of treatment, particularly for small saphenous reflux.  相似文献   
999.
OBJECTIVE: A comprehensive study was performed to evaluate the accuracy of a newly developed CT-free, intra-operative planning and navigation system for anterior spine surgery. MATERIALS AND METHODS: Instruments and an image intensifier were tracked using the SurgiGATE navigation system. A laboratory study was performed on 27 plastic vertebrae. Fiducial markers were implanted in the vertebrae for accuracy evaluation purposes, and a dynamic reference base was placed on the vertebrae to establish a patient coordinate system (P-COS). Two fluoroscopic images were used for intra-operative planning. The graft bed plan was recorded in P-COS, followed by surgical formation of the graft bed, which was visualized. To evaluate the accuracy, the vertebrae were scanned with CT, and the markers were used to calculate an accurate paired-point registered transformation between the CT coordinate system and P-COS. RESULTS: Using the new SPO module, accurate planning and navigation of a resection of the vertebral body is possible using two fluoroscopic images. The overall mean error between the planned resection volume and the actual resection was 0.98 mm. In addition, the module can serve as an educational tool for training spine surgeons. CONCLUSIONS: The new fluoroscopy-based system can be used safely for accurate performance of anterior resection during spondylodesis. New methods for safe and accurate registration during anterior spine surgery need to be developed.  相似文献   
1000.
Transabdominal sacrocolpopexy has been shown, in multiple long-term studies of its success and durability, to be the definitive treatment option for post-hysterectomy vaginal vault prolapse. It is, however, associated with greater morbidity than vaginal repair. We describe a minimally invasive technique for vaginal vault prolapse repair and present our experience with a minimum of one-year follow-up. The surgical technique involves five laparoscopic ports—three for the da Vinci robot and two for the assistant. After appropriate dissection a polypropylene mesh is attached to the sacral promontory and to the vaginal apex by use of Gore-Tex sutures. The mesh material is then covered by the peritoneum. Patient analysis focused on complications, urinary continence, patient satisfaction, and morbidity, with a minimum of 12 months follow-up. Forty-two patients with post-hysterectomy vaginal vault prolapse underwent robot-assisted laparoscopic sacrocolpopexy at our institute and 35 have a minimum of 12 months follow-up, with a mean follow-up of 36 months (range 12–48) in the group. Mean age was 67 (47–83) years and mean operating time was 3.1 (2.15–4.75) h for the entire cohort. All but one patient were discharged home on postoperative day one; one patient left on postoperative day two. One developed recurrent grade three rectocele, one had recurrent vault prolapse, and two suffered from vaginal extrusion of mesh. All patients were satisfied with their outcome. The robot-assisted laparoscopic sacrocolpopexy is a minimally invasive technique for vaginal vault prolapse repair, combining the advantages of open sacrocolpopexy with the reduced morbidity of laparoscopy. We observed reduced hospital stay, low occurrence of complications, and high patient satisfaction, with a minimum of 1-year follow-up. Most importantly, the long-term results of the robotic repair are similar to those of open repair, but with significantly less morbidity.  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