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   1287353篇
  免费   98862篇
  国内免费   2000篇
耳鼻咽喉   18514篇
儿科学   44610篇
妇产科学   35245篇
基础医学   183403篇
口腔科学   33851篇
临床医学   112509篇
内科学   259862篇
皮肤病学   28215篇
神经病学   101170篇
特种医学   51409篇
外国民族医学   661篇
外科学   197856篇
综合类   27282篇
现状与发展   1篇
一般理论   394篇
预防医学   96461篇
眼科学   28055篇
药学   95244篇
  2篇
中国医学   2424篇
肿瘤学   71047篇
  2018年   13301篇
  2017年   10091篇
  2016年   11035篇
  2015年   12518篇
  2014年   17386篇
  2013年   26533篇
  2012年   36530篇
  2011年   38602篇
  2010年   23101篇
  2009年   22064篇
  2008年   37100篇
  2007年   39708篇
  2006年   39945篇
  2005年   38888篇
  2004年   38019篇
  2003年   36830篇
  2002年   36116篇
  2001年   64280篇
  2000年   66807篇
  1999年   56681篇
  1998年   15241篇
  1997年   13858篇
  1996年   14294篇
  1995年   13539篇
  1994年   12838篇
  1993年   11864篇
  1992年   44726篇
  1991年   43606篇
  1990年   42362篇
  1989年   40274篇
  1988年   37023篇
  1987年   36371篇
  1986年   33739篇
  1985年   32388篇
  1984年   24239篇
  1983年   20349篇
  1982年   11778篇
  1981年   10737篇
  1980年   9557篇
  1979年   21408篇
  1978年   14859篇
  1977年   12568篇
  1976年   11738篇
  1975年   12656篇
  1974年   14719篇
  1973年   14150篇
  1972年   12983篇
  1971年   11767篇
  1970年   11085篇
  1969年   10056篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
995.
996.
997.
Medial epicondylitis is a chronic noninflammatory condition resulting from mechanical injury. Despite many treatment options, including rest, medications, physiotherapy and operative interventions, the results are too often poor; thus new treatment options are sought. We treated 4 men with chronic epicondylitis (5 affected joints) with extracorporeal shock wave therapy after failed attempts of other treatments. The patients’ complaints were graded with the Nirschl scoring system prior to and six months after therapy. The treatment consisted of three sessions, at 20-day intervals, of 3000 pulses of ultrasonic shock waves from a Piezolith 3000 unit (energy dosage was gradually increased to reach step 10 equaling 0.9 mJ/mm2). At the 6-month follow-up, no patient was pain free. Three cases had slightly lower Nirschl scores than prior to the procedure but the patients rated this difference as insignificant; two cases were unchanged. No complications were observed but all patients rated the procedure as very unpleasant. The well recognized biologic effects of ultrasonographic waves (heat generation, oscillations, cavitation, etc.) that result in functional and structural changes of cellular membranes with sonochemical reactions (acceleration of normal metabolism, oxygenation and reduction in water solutions, polymer degradation, etc.), even if present in our cases, did not result in a noticeable decrease of symptoms, even though we used high energy and more impulses per session. Significant variations in methodology make inconclusive the results of numerous reports on the use of extracorporeal shock waves in epicondylar degenerative problems, although ineffectiveness of such therapy is the conclusion of a review by Haake and colleagues.  相似文献   
998.
Teeth with white spot lesions (WSL) might be more prone to enamel loss during bracket debonding. This in vitro study compared enamel loss from teeth with (n = 14) and without (n = 14) WSL after polishing with low-speed finishing burs or disks (Sof-Lex, 3M ESPE, St Paul, Minn). Debonded surfaces were analyzed with a contact stylus profilometer, and digitized data were compared with baseline readings by using AnSur NT software (Regents, University of Minnesota, Minneapolis, Minn). Specimen surfaces were also examined with a scanning electron microscope. Two-way analysis of variance was performed to analyze the data. In teeth without WSL, the volume losses were 0.16 mm(3) for the bur group and 0.10 mm(3) for the disk group; the mean maximum depths were 47.7 microm for the bur group and 54.3 microm for the disk group. In teeth with WSL, the volume losses were 0.06 and 0.17 mm(3), and the mean maximum depths were 35.1 and 48.7 microm for the bur and disk groups, respectively. There were no significant differences in enamel loss between the 2 groups of teeth without WSL (P =.12). However, in teeth with WSL, the burs removed less enamel than the disks (P = 0.006). Scanning electron microscope examination showed that any damage on the enamel surface was usually located in the cervical third of the teeth. On most specimens, even though tooth surfaces appeared resin-free to the naked eye, there were remnants of it. The differences between groups were so small that they might be clinically insignificant.  相似文献   
999.
The 6-min walking distance (6MWD) test is used in clinical practice and research into patients with chronic obstructive pulmonary disease (COPD). However, little is known about natural long-term change in this parameter. The 6MWD was measured at baseline and then annually for 5 yrs in 294 patients with COPD and its annual rate of decline was determined. Forced expiratory volume in one second (FEV1) was also measured and the relationship between changes in both markers was explored. At baseline, the median 6MWD was 380 m (range 160-600 m). It declined by 19% (16 m.yr(-1)) over the 5 yrs compared with baseline in patients with American Thoracic Society/European Respiratory Society stage III COPD (FEV1 30-50% predicted) and by 26% (15 m.yr(-1)) in patients with stage IV COPD (FEV1 <30% pred). Over the 5-yr follow-up, the proportion of patients with a minimal clinically significant decline of 54 m increased with the severity of the disease. It was 24% in stage II, 45% in stage III, and 63% in stage IV disease. In contrast, the rate of decline of FEV1 was greater in patients with milder airflow obstruction and lesser in patients with lower absolute FEV1 values. In conclusion, the 6-min walking distance test provides increasingly useful information as the severity of chronic obstructive pulmonary disease increases.  相似文献   
1000.
Obstructive sleep apnoea is associated with increased blood pressure and other features of the metabolic syndrome. The aim of the present study was to determine the relative effectiveness of continuous positive airway pressure (CPAP) in modifying these outcomes. A randomised placebo-controlled blinded crossover trial comparing cardiovascular and metabolic outcomes after 6 weeks of therapeutic and sham CPAP was performed in 34 CPAP-na?ve patients (mean+/-SD body mass and respiratory disturbance indices were 36.1+/-7.6 and 39.7+/-13.8, respectively). Mean waking systolic and diastolic blood pressure fell by 6.7 and 4.9 mmHg, respectively, when compared with sham CPAP. No change was observed in glucose, lipids, insulin resistance or the proportion of patients with metabolic syndrome. In CPAP-compliant patients the fall in blood pressure was greater and the baroreceptor sensitivity improved significantly but no metabolic variable changed. In obese Caucasians with untreated obstructive sleep apnoea, continuous positive airways pressure can improve baroreceptor responsiveness and reduce waking blood pressure within 6 weeks, but this treatment period was insufficient to modify insulin resistance or change the metabolic profile. The mechanisms underlying this difference in the time course of blood pressure and metabolic response to continuous positive airway pressure in obstructive sleep apnoea requires further exploration.  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