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   2119篇
  免费   113篇
  国内免费   25篇
耳鼻咽喉   9篇
儿科学   86篇
妇产科学   26篇
基础医学   203篇
口腔科学   51篇
临床医学   149篇
内科学   456篇
皮肤病学   51篇
神经病学   306篇
特种医学   192篇
外科学   346篇
综合类   15篇
预防医学   114篇
眼科学   13篇
药学   107篇
肿瘤学   133篇
  2023年   7篇
  2022年   27篇
  2021年   41篇
  2020年   20篇
  2019年   33篇
  2018年   58篇
  2017年   32篇
  2016年   41篇
  2015年   50篇
  2014年   69篇
  2013年   96篇
  2012年   113篇
  2011年   111篇
  2010年   81篇
  2009年   71篇
  2008年   93篇
  2007年   114篇
  2006年   90篇
  2005年   103篇
  2004年   80篇
  2003年   75篇
  2002年   77篇
  2001年   53篇
  2000年   61篇
  1999年   52篇
  1998年   46篇
  1997年   31篇
  1996年   37篇
  1995年   29篇
  1994年   27篇
  1993年   15篇
  1992年   35篇
  1991年   29篇
  1990年   28篇
  1989年   44篇
  1988年   36篇
  1987年   28篇
  1986年   25篇
  1985年   26篇
  1984年   24篇
  1983年   25篇
  1982年   15篇
  1980年   14篇
  1979年   12篇
  1977年   8篇
  1976年   22篇
  1975年   7篇
  1974年   5篇
  1970年   6篇
  1967年   5篇
排序方式: 共有2257条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Microvascular involvement represents one of the first apparent steps in many autoimmune diseases such as rheumatoid arthritis (RA). Early in the disease, peripheral microangiopathy may be easily recognized and studied by videocapillaroscopy. The aim of this study has been to observe the differences in labial microcirculation between healthy patients and patients suffering from RA. A total of 30 healthy patients and 30 patients suffering from RA were examined. The patients with conditions known to compromise microcirculation, such as diabetes, hypertension, or some pharmacological treatments were not included in the study. All the patients were non-smokers. Labial capillaroscopy was used to investigate the characteristics of microcirculation. Visibility, course, tortuosity, as well as the possible presence of microhemorrhages, the average caliber of the capillary loops and the number of visible capillary loops per square millimeter were evaluated for each patient. The investigation was simple, non-invasive, and repeatable for each patient. In patients suffering from RA, it was possible to observe a reduced caliber of capillaries, as well as greater elongated capillaries, in comparison to controls. This study shows that capillary alterations in patients suffering from RA occur in labial mucosa microcirculation; such evidence could be extremely important in the diagnosis of suspected RA.  相似文献   
5.
The Stranger     
J Emerg Nurs 1998;24:622.  相似文献   
6.
Chitambar  CR; Zivkovic  Z 《Blood》1989,74(2):602-608
Information regarding transferrin (Tf) receptor degradation is largely incomplete. HL60 cells were shown to release to their growth medium a Tf-binding protein which could be immunoprecipitated by anti-Tf receptor monoclonal antibodies (MoAbs) B3/25 and OKT9. Soluble Tf receptor was detected in the medium within one hour of replating of cells, and its release was inhibited at 4 degrees C. The affinity of Tf for the soluble receptor released by cells (kd = 2.3 x 10(-10) mol/L) was slightly lower than its affinity for the detergent-solubilized cellular receptor (kd = 1.2 x 10(-10) mol/L). 125I-Tf internalized and released by cells subsequently bound to Tf receptor released by the same cells, and soluble Tf receptor in the conditioned medium (CM) inhibited 125I-Tf binding to intact cells. The soluble Tf receptor isolated from the CM was smaller (78,000 daltons) than the cell surface receptor (94,000 daltons) when analyzed by gel electrophoresis under reducing conditions. Isolated cell membranes readily released soluble receptor; however, this release could be blocked by protease inhibitors. The soluble Tf receptor may represent the extracytoplasmic domain of the cellular Tf receptor released from the surface of HL60 cells through proteolytic cleavage by a membrane-based protease.  相似文献   
7.
8.
Hemorrhagic vascular complications of endoscopic transsphenoidal surgery.   总被引:1,自引:0,他引:1  
Two hundred and fifty consecutive patients operated on by an endoscopic endonasal transsphenoidal approach were retrospectively analyzed in order to evaluate hemorrhagic vascular complications occurring during or after the surgical procedure and their appropriate management. Vascular complications of endoscopic transsphenoidal surgery are identical to those of a microsurgical transsphenoidal approach. Damage to the sphenopalatine artery and to the internal carotid artery (ICA), which are the most frequent vascular troubles, may require technical tricks because of some aspects connected to the approach itself and of the physical properties of the endoscope. Furthermore, the progress in interventional neuroradiology in the last decades offers new solutions in respect to the past, where the use of the surgical microscope was already a tremendous progress. The anatomic substrate of each complication is discussed, along with the peculiar surgical details related to it.  相似文献   
9.
Cancers of the middle umbilical fold are very infrequent, making up 0.1% to 0.7% of all bladder tumors. This type of tumor affects male subjects in 60% to 75% of cases, in the 5th or 6th decade of life. In more than 90% of all cases, the lesion is a mucosecretory adenocarcinoma developing from embryonic remains within the wall of the bladder and respecting the superficial urothelium of the bladder, which is affected only secondarily, contrary to what occurs in the other adenocarcinomas of the bladder. The pathogenesis remains controversial, especially the role of middle umbilical fold patency and of bladder carcinogens. The diagnosis is most often established late, because of a long clinical latency. It is mainly based on ultrasonography and computed tomography. Explorations of the bladder are useful only at an advanced stage. The prognosis is very poor, survival at 5 years ranging from 6.5% to 25% according to the authors. The treatment is mainly surgical. Only extensive exeresis with partial cystectomy extending to the peri- and supravesical environment, including the peritoneum and the umbilicus, and associated with pelvic lymphadenectomy may give some hope. Chemotherapy and radiation therapy, either alone or complementary, are disappointing. The prognosis may be improved only by an early diagnosis.  相似文献   
10.
Prior studies have shown that pneumothorax is one of the more difficult entities to diagnose with digitized radiography. This study was designed to test whether increasing resolution from 1.25 to 2.5 line pairs per millimeter (lp/mm) and image processing (edge enhancement from unsharp masking) would increase accuracy and confidence in the diagnosis of pneumothorax, as well as normal cases and other forms of lung disease. Conventional radiographs were digitized with use of a laser reader and then reformatted as film hard copy. Eleven observers read 35 cases reformatted in three different ways (1.25 lp/mm, 2.5 lp/mm, 1.25 lp/mm unsharp mask). The images with finer resolution (2.5 lp/mm) and unsharp mask images were superior to those with coarser resolution (1.25 lp/mm) for the diagnosis of pneumothorax. There was no difference in diagnostic accuracy for normal patients. For abnormalities other than pneumothorax, the unsharp mask images were significantly worse. Confidence in the diagnosis of pneumothorax and other abnormalities was highest with the finest resolution (2.5 lp/mm).  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