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   24266篇
  免费   1822篇
  国内免费   78篇
耳鼻咽喉   406篇
儿科学   834篇
妇产科学   392篇
基础医学   2502篇
口腔科学   545篇
临床医学   2208篇
内科学   5318篇
皮肤病学   581篇
神经病学   1290篇
特种医学   1122篇
外国民族医学   1篇
外科学   4577篇
综合类   329篇
一般理论   16篇
预防医学   1192篇
眼科学   852篇
药学   2082篇
中国医学   41篇
肿瘤学   1878篇
  2023年   226篇
  2022年   423篇
  2021年   1014篇
  2020年   491篇
  2019年   851篇
  2018年   981篇
  2017年   619篇
  2016年   674篇
  2015年   703篇
  2014年   1045篇
  2013年   1217篇
  2012年   1818篇
  2011年   1772篇
  2010年   895篇
  2009年   832篇
  2008年   1312篇
  2007年   1233篇
  2006年   1153篇
  2005年   1013篇
  2004年   901篇
  2003年   758篇
  2002年   665篇
  2001年   587篇
  2000年   553篇
  1999年   489篇
  1998年   162篇
  1997年   135篇
  1996年   141篇
  1995年   143篇
  1994年   113篇
  1993年   97篇
  1992年   267篇
  1991年   285篇
  1990年   248篇
  1989年   212篇
  1988年   208篇
  1987年   219篇
  1986年   192篇
  1985年   177篇
  1984年   111篇
  1983年   126篇
  1982年   85篇
  1981年   70篇
  1979年   129篇
  1978年   77篇
  1977年   69篇
  1975年   58篇
  1974年   65篇
  1973年   88篇
  1970年   58篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Fifty cases with chronic idiopathic urticaria of more than 3 months duration were selected and divided into two groups. Group 'A' was given 10 mg loratadine once daily, while group 'B' was given pheniramine maleate 25 mg, twice daily for one month. All patients were followed for one month more. 48% excellent response was observed in group 'A' while 16% excellent response was observed in group 'B'. Good response was observed in 24% of patients in group 'A', while in group 'B' 16% of patients had good response. No side effects were observed in loratadine group, while drowsiness was observed in pheniramine group.  相似文献   
122.
Patel MC  Berman LH  Moss HA  McPherson SJ 《Radiology》1999,211(2):579-583
In 21 consecutive patients, the authors analyzed changes in venous Doppler waveforms of damped or diminished cardiac pulsatility and respiratory phasicity. Each patient was suspected of having upper limb venous thrombosis, but thrombus was not visible at gray-scale ultrasonography (US) in the subclavian and brachiocephalic veins. US findings were compared with phlebographic findings. The results show that US can be used to establish the presence or absence of thrombosis in the distal portion of the brachiocephalic or subclavian veins, which are inaccessible to direct insonation.  相似文献   
123.
Water-suppression MRI: role in the evaluation of osseous lesions   总被引:1,自引:0,他引:1  
The efficacy of chemical shift based water-suppression MRI in the evaluation of bone marrow lesions has not been previously reported. T1-weighted images without and with water suppression were compared in five patients with 16 lesions. There was a significant improvement in the contrast-to-noise ratio (from 4.32 to 5.95, P < 0.01) and contrast ratio (from 1.71 to 5.69, P < 0.004) with water suppression. Water suppression may be useful clinically by increasing the conspicuity of bone marrow lesions.  相似文献   
124.
125.
Since its commercial introduction a decade ago, the technique of dual-energy X-ray absorptiometry (DXA) has been widely recognized as a useful and sensitive method of measuring changes in bone mineral density (BMD) at selected sites in the skeleton such as the spine and proximal femur. Because of their high precision and stable calibration, DXA scanners are frequently used in clinical trials to evaluate new treatments for osteoporosis. Quality assurance procedures based on regular scanning of phantoms are widely adopted in such trials, and continuity of the phantom BMD measurements is generally believed to ensure continuity in the in-vivo calibration. We report a change in calibration of a DXA scanner that occurred during a clinical trial where the calibration shift was different for the spine and femur sites and was not predicted or explained by the standard quality control procedures using phantoms. However, we show that provided patients enrolled in studies are thoroughly randomized and the statistical analysis is confined to the differences between the treated and control groups, then the effects of such calibration shifts on conclusions regarding the efficacy of treatment are considerably smaller than the random statistical errors. Received: 12 February 1998 / Accepted: 20 May 1998  相似文献   
126.
An inhibitory anti-factor IX/IXa antibody (BC2) has been investigated as an anti-thrombotic agent in a rat venous thrombosis model. The treatment of rats post-injury with a single bolus dose of BC2 (3 mg/kg, i.v.) resulted in an approximately 4 fold reduction in venous thrombus mass (P = 0.043). This efficacy was matched by a minimal (<2.5 fold) prolongation of the aPTT and had no effect on the prothrombin time (PT). Heparin by comparison, given as a bolus followed by continuous infusion, at doses comparable in efficacy at reducing thrombus formation, prolonged the aPTT >50 fold. These results demonstrate that the anti-factor IX/IXa antibody (BC2), when compared to heparin, can effectively reduce venous thrombosis with less disruptive consequences on blood clotting.  相似文献   
127.
We present the clinical and histopathological features and the diagnostic difficulties encountered in five children affected by a motor neuron disorder other than spinal muscular atrophy. Investigations performed suggested the diagnosis of ponto-cerebellar hypoplasia type 1 (PCH-1). Severe respiratory difficulty was present at birth in two of these children; hypotonia, arthrogryposis, microcephaly and nystagmus were present in all. Early and progressive bulbar involvement with swallowing difficulties and stridor was also a common feature in these infants. Severe cognitive delay was invariably present. Brain magnetic resonance imaging showed ponto-cerebellar hypoplasia in four children while striking atrophy of the cerebellar vermis and cerebellar hemispheres were present in the fifth child. Electrophysiological and pathological investigations of proximal muscles performed at presentation in all these children were not conclusive, while the post-mortem studies, or the study of distal muscles during life, showed a clear neurogenic picture. Genetic studies excluded involvement of the SMN gene, or of other genes located on chromosome 5q, confirming that ponto-cerebellar hypoplasia type 1 is a different entity from typical proximal spinal muscular atrophy.  相似文献   
128.
We describe a patient with a Mason type-III fracture of the head of the radius associated with traumatic dislocation of the elbow. The radial head was intact throughout its circumference despite being completely detached from the shaft and devoid of any soft-tissue attachments. Severe comminution of the radial neck prevented reconstruction by internal fixation and precluded prosthetic replacement of the head. The head was fixed to the shaft with a tricortical iliac-crest bone graft which replaced the neck. Two years later, the patient had a stable elbow with flexion from 10 degrees to 130 degrees. Radiologically, the head of the radius appeared to be viable and the bone graft had incorporated.  相似文献   
129.
Anaesthesia for LSCS in a morbidly obese patient   总被引:1,自引:0,他引:1  
The management of a morbidly obese parturient with a body mass index of 88 is reported. She developed asthma during the pregnancy. Lumbar epidural anaesthesia was successfully used for an elective caesarean section and tubal ligation.  相似文献   
130.
A novel topical clofazimine (CLO) gel formulation containing liposomally encapsulated CLO, was prepared and investigated in vitro followed by a clinical evaluation. CLO liposomes were prepared by the lipid film hydration technique. Comparative in vitro diffusion studies were conducted with plain and liposomal CLO in HPMC K4M gel base (2% and 5%) using human cadaver skin (HCS). A double blind clinical study was conducted on eight leprosy patients. The results of these studies show that the new liposomal topical gel formulation not only prolongs the drug release but also promotes drug retention by the skin. Studies further support formation of a reservoir of drug on the skin modifying therapeutic efficacy of the formulation. The new liposomal gel formulation of CLO considerably reduces the healing time of external lesions due to a significantly prolonged skin residence time compared to plain CLO gel and hence is expected to reduce the time needed for leprosy treatment.  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