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   868168篇
  免费   71212篇
  国内免费   1843篇
耳鼻咽喉   12821篇
儿科学   24849篇
妇产科学   25243篇
基础医学   125119篇
口腔科学   25552篇
临床医学   76158篇
内科学   165747篇
皮肤病学   17058篇
神经病学   70590篇
特种医学   35492篇
外国民族医学   171篇
外科学   136887篇
综合类   24728篇
现状与发展   2篇
一般理论   273篇
预防医学   67561篇
眼科学   20661篇
药学   65117篇
中国医学   1596篇
肿瘤学   45598篇
  2018年   7432篇
  2015年   7819篇
  2014年   11240篇
  2013年   16968篇
  2012年   23013篇
  2011年   24121篇
  2010年   14041篇
  2009年   13203篇
  2008年   22872篇
  2007年   24937篇
  2006年   24804篇
  2005年   24417篇
  2004年   23964篇
  2003年   23069篇
  2002年   22140篇
  2001年   36008篇
  2000年   36665篇
  1999年   31074篇
  1998年   9309篇
  1997年   8611篇
  1996年   8542篇
  1995年   8051篇
  1994年   7782篇
  1992年   26796篇
  1991年   26235篇
  1990年   25759篇
  1989年   24816篇
  1988年   23330篇
  1987年   23008篇
  1986年   21849篇
  1985年   21213篇
  1984年   16433篇
  1983年   14075篇
  1982年   8895篇
  1981年   8245篇
  1980年   7724篇
  1979年   16804篇
  1978年   12154篇
  1977年   10228篇
  1976年   9379篇
  1975年   10204篇
  1974年   12692篇
  1973年   12197篇
  1972年   11584篇
  1971年   10723篇
  1970年   10249篇
  1969年   9935篇
  1968年   8932篇
  1967年   8265篇
  1966年   7683篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
We report a case of malakoplakia in association with colonic adenocarcinoma. Tumour-associated malakoplakia in the gastrointestinal tract is a rare finding, generally confined to the colon. It may be locally aggressive, with invasion of pericolic tissues, but is always located adjacent to the tumour. This contrasts with the often more diffuse, multifocal distribution of colonic malakoplakia in association with other pathologies.  相似文献   
972.
973.
A multicentre, randomised, placebo-controlled, dose-ranging study was conducted to investigate the therapeutic activity and sustained efficacy of tiludronate (200 mg, 400 mg and 600 mg once daily) taken orally for 12 weeks in patients with Paget''s disease. Serum alkaline phosphatase concentrations were compared with baseline at weeks 12 and 24; treatment success was defined as a 50% reduction compared with baseline. Changes in the hydroxyproline: creatinine ratio were also measured. Pain was assessed using the Huskisson Visual Analogue Scale and by questionnaire. Patients completing at least 11 weeks of treatment were followed-up 18 months later by postal questionnaire. Significantly greater numbers of patients in the tiludronate groups successfully responded to treatment compared with the placebo group. A dose-response was observed; the percentage of patients responding to treatment being 31% (200 mg), 52% (400 mg) and 82% (600 mg) at week 12 and 45% (200 mg), 70% (400 mg) and 82% (600 mg) at week 24. Tiludronate treatment also significantly reduced hydroxyproline: creatinine ratios compared with placebo, again showing a dose response. Dose-related gastrointestinal symptoms were the commonest adverse events, occurring in 2.4%, 11.0%, 5.5% and 18.9% of patients receiving placebo and tiludronate 200, 400 and 600 mg daily, respectively. The response to oral tiludronate was sustained for more than 18 months in some patients and there was evidence of a reduction in the longer term complications of the disease. These results show that oral tiludronate is an effective, well-tolerated treatment for Paget''s disease; the 400 mg once daily dose appears to offer the optimum balance of efficacy and tolerance.  相似文献   
974.
975.
976.
One hundred insulin-dependent diabetic patients (age < 45 years, 53 smokers) were followed for six years. The age, duration of diabetes and mean glycated haemoglobin levels, were comparable between the smokers and non-smokers. Microvascular complications (retinopathy and increased urine albumin excretion) were commoner and more severe in the smoking group at six years, particularly in heavy smokers. Of the 45 original smokers reviewed at six years, 12 (27%) had stopped, six of whom had developed microvascular complications. Only two of the ''heavy'' initial smokers, likely to be at most risk, had stopped smoking, and three original non-smokers had started smoking.  相似文献   
977.
The application of Doppler-tipped guide wires to measure blood flow velocity in coronary and peripheral arteries has been described previously as a valuable means of functional assessment in interventional cardiological procedures. In animal studies intravascular Doppler has been used in the cerebrovascular system, and this appears to be an important field of application for this new technique. We used intravascular haemodynamic monitoring by the Doppler guide wire during neuroendovascular procedures in patients with different cerebrovascular diseases and evaluated the clinical feasibility of the method. We found it a safe technique which complements morphological angiographic information with valuable functional data. Further studies may be expected to demonstrate the relation of flow parameters to clinical outcome. Received: 16 January 1996 Accepted: 30 January 1996  相似文献   
978.
Measurements of the volume magnetic susceptibility of solids using the classical Gouy balance approach are hampered by variations in apparent density of the packed powder. In this paper a quantitative NMR measurement of the volume magnetic susceptibility of powdered solids is described and the volume susceptibility of bone is reported. The technique is based on the measurement of changes in incremental linewidth (1/πT2′) induced in a marker fluid whose susceptibility can be predictably modified by changing the composition, such as by addition of a soluble diamagnetic compound. The spectroscopic linewidth of the marker fluid is determined by the susceptibility difference between the fluid and the suspended solid. Changes in the linewidth are accompanied by bulk magnetic susceptibility induced frequency shifts in the fluid resonance. Correlating the two dependencies allows measurement of the absolute volume susceptibility of the solid. The susceptibility of bovine rib bone was found to be ?0.90 ± 0.02 × ? 10?6 (CGS) confirming previous estimates which suggested bone to be more diamagnetic than the marrow constituents. Knowledge of the susceptibility of bone is relevant in view of the growing interest in MRI osteodensitometric techniques.  相似文献   
979.
The talar beak is a well-described secondary sign of talocalcaneal coalition but is not pathognomonic of the condition and may be seen in other causes of restricted or abnormal subtalar motion. We present an unusual complication of talar beaks in two patients who sustained fractures through their beaks. One of the patients described did not have a talocalcaneal coalition but had developed a beak following a compound fracture dislocation of the ankle joint complicated by infection, a previously undescribed predisposing cause.  相似文献   
980.
A review of factors contributing to early mortality after cardiac transplantation revealed that up to 25 % of deaths were due to primary graft dysfunction unrelated to rejection or infection. In light of this finding, evaluation of a donor heart with regard to its suitability for transplantation takes on added importance. In an effort to screen the suitability of donor hearts in the region covered by the Northwest Organ Procurement Agency (USA), all donors are evaluated by two-dimensional transthoracic echocardiography as part of the initial evaluation. A total of 110 donor echocardiograms were reviewed and an attempt was made to correlate the 30-day outcome with the parameters measured. An unexpected finding was that the presence of left ventricular hypertrophy in the donor heart was associated with an increase in the incidence of donor heart dysfunction compared with donors with normal echocardiographic profiles (33 % vs 3 %, P = 0.007). Received: 12 February 1996 Received after resision: 27 June 1997 Accepted: 14 July 1997  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