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   1456407篇
  免费   95343篇
  国内免费   2951篇
耳鼻咽喉   23618篇
儿科学   44414篇
妇产科学   43961篇
基础医学   210264篇
口腔科学   42736篇
临床医学   118097篇
内科学   286283篇
皮肤病学   35954篇
神经病学   114927篇
特种医学   59084篇
外国民族医学   435篇
外科学   225556篇
综合类   31471篇
现状与发展   6篇
一般理论   440篇
预防医学   96112篇
眼科学   36400篇
药学   104266篇
  4篇
中国医学   3038篇
肿瘤学   77635篇
  2018年   12008篇
  2015年   14703篇
  2014年   19975篇
  2013年   29619篇
  2012年   36209篇
  2011年   37793篇
  2010年   23976篇
  2009年   23490篇
  2008年   36682篇
  2007年   39640篇
  2006年   40597篇
  2005年   38896篇
  2004年   37640篇
  2003年   35449篇
  2002年   34055篇
  2001年   64370篇
  2000年   66044篇
  1999年   56231篇
  1998年   15734篇
  1997年   14471篇
  1996年   14298篇
  1995年   13731篇
  1994年   12954篇
  1993年   12023篇
  1992年   44228篇
  1991年   42516篇
  1990年   41698篇
  1989年   40556篇
  1988年   37919篇
  1987年   37408篇
  1986年   35818篇
  1985年   33883篇
  1984年   25706篇
  1983年   21761篇
  1982年   13513篇
  1981年   12335篇
  1979年   24705篇
  1978年   17956篇
  1977年   15536篇
  1976年   13962篇
  1975年   15969篇
  1974年   18802篇
  1973年   18308篇
  1972年   17424篇
  1971年   16217篇
  1970年   15391篇
  1969年   14950篇
  1968年   13927篇
  1967年   12501篇
  1966年   11677篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
To examine the prevalence of Internet sex networking among men who have sex with men (MSM) in Hong Kong and risk behaviors associated with the behavior, a telephone survey of 15,230 Hong Kong Chinese men aged 18-60 was conducted. Of the 283 active MSM (having engaged in some MSM behaviors in the last 6 months) identified, 17.7% had networked for MSM partners via the Internet in the last 6 months. Younger age (odds ratio [OR] for age < or = 25 vs. age >25 = 4.67, 95% confidence interval [CI] = 2.35-9.28) and being an anal-sex MSM (OR = 4.72, 95% CI=2.36-9.44) were independent predictors of Internet sex networking. Being an Internet sex networker was associated with some risk behaviors such as having contracted a sexually transmitted disease (adjusted OR = 4.79, 95% CI = 1.34-17.11), having had > or = 3 MSM partners (adjusted OR = 4.74, 95% CI = 2.20-10.23), and having engaged in anal sex (adjusted OR = 3.95, 95% CI = 1.89-8.23). HIV prevention programs for MSM should thereby include Internet-based interventions.  相似文献   
92.
The incidence of asthma has been reported to be associated with obesity. An alternative analysis, of net change in prevalence, does not require exclusion of those with asthma at baseline. Follow-up data were obtained from 9,552 participants in the European Community Respiratory Health Survey and the Swiss cohort Study on Air Pollution and Lung Disease in Adults. Incidence of asthma was analysed by proportional hazards regression, and net changes in symptoms and asthma status by generalised estimating equations, by obesity group. Incidence and net change in ever having had asthma were greater in females than in males, and in participants who remained obese compared with those who were never obese (hazard ratio 2.00, 95% confidence interval 1.25-3.20; excess net change 2.8%, 0.4-5.3% per 10 yrs). The effect of being obese on net change in diagnosed asthma was greater in females than in males, but for net change in wheeze without a cold it was greater in males. The present results are consistent with asthma being more frequently diagnosed in females, especially obese females. These findings may help to explain the reports of a stronger association between asthma and obesity in females than in males.  相似文献   
93.
94.
The finer branches of the biliary tree (FBBT) contain a regenerative compartment. We hypothesized that preservation of the FBBT together with its microvasculature will lead to recovery of biliary damage and prolonged preservation of bile ductules during the development of chronic liver allograft rejection. The interlobular bile ducts, portal bile ductules and extraportal biliary cells with and without microvessels were studied in sequential biopsies in five patients who fulfilled the Banff criteria of early chronic rejection (CR) (imminence group). Biopsies of CR patients (n = 12) served as controls. Biopsies were double immunostained with CD34 (microvessels) and cytokeratin 7 (biliary structures). Proliferation and proangiogenic activity were assessed with Ki67 and VEGF-A immunostaining. Severe damage of bile ducts in the imminence group did not progress to significant bile duct loss. This was associated with a high proliferative activity in all biliary structures and preservation of the microvascular compartment. VEGF-A expression was increased in all but the reperfusion biopsies. In conclusion, both regenerative activity of the FBBT and an intact microvascular compartment are associated with less damage of the biliary tree and could therefore be prerequisites for biliary regeneration.  相似文献   
95.
96.
Atherosclerotic renal artery stenosis (ARAS) may cause hypertension, progressive renal failure, and recurrent pulmonary edema. It typically occurs in high risk patients with coexistent vascular disease elsewhere. Most patients with ARAS are likely to die from coronary heart disease or stroke before end-stage renal failure occurs. Recent controlled trials have shown that most patients undergoing angioplasty to treat renovascular hypertension still need antihypertensive agents 6 or 12 months after the procedure. Nevertheless, the number of antihypertensive agents required to control blood pressure adequately is lower following angioplasty than for medication alone. Trials assessing the value of revascularization for preserving renal function or preventing clinical events are only in the early recruitment phase. Revascularization should be undertaken in patients with ARAS and resistant hypertension or heart failure, and probably in those with rapidly deteriorating renal function or with an increase in plasma creatinine levels during angiotensin-converting enzyme inhibition. With or without revascularization, medical therapy using antihypertensive, hypolipidemic and antiplatelet agents is necessary in almost all cases.  相似文献   
97.
98.
A fall onto the hand can be followed by ligament ruptures, bone fractures or dislocated fractures of the carpus. The diagnosis is based on history, clinical evaluation, and X-ray examination in two perpendicular planes, followed if necessary by CT scan or MRI scan. Lesions of the scapholunate ligaments cannot be definitely excluded except by arthroscopy. As well as fractures of the carpometacarpal joints, fractures involving the ring structure of the carpus or ligament ruptures between carpal bones are frequently observed, and these lead to significantly impaired biomechanics. The prognosis is poor. The discontinuity of the ring must be repaired by means of osteosynthesis and/or suturing ligaments, with the carpal bones held in place by temporary arthrodesis using K-wires. Dislocation in this region requires rapid realignment, as untreated perilunate dislocation or dislocation of the lunate bone will lead to serious secondary damage, which can only be treated by salvage operations involving loss of function. Inappropriate treatment of an injury to the heel of the hand can lead to carpal collapse.  相似文献   
99.
100.
Thoraxtrauma     
Chest injuries can be sustained in isolation or in association with multiple injuries. Life-threatening complications may ensue because organs that are vital to survival of the organism are situated within the thoracic cavity. These complications include airway obstruction, tension pneumothorax, wide open pneumothorax, flail chest, cardiac tamponade and massive hemothorax. The mortality of patients hospitalized with chest injury can be as high as 10%. Clinical examination and awareness of the possibility of other injuries (high level of suspicion) are essential, and standard chest X-ray, ultrasound and thoracic computed tomography may also be needed for the diagnosis. The first part of this serial paper on the management of chest injuries focuses on anatomical aspects, pathophysiology and symptoms, but mainly on the indications for the standard diagnostic procedures and further high-tech examinations.  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