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   6924篇
  免费   599篇
  国内免费   112篇
耳鼻咽喉   106篇
儿科学   1106篇
妇产科学   224篇
基础医学   1574篇
口腔科学   435篇
临床医学   329篇
内科学   1021篇
皮肤病学   113篇
神经病学   470篇
特种医学   314篇
外科学   951篇
综合类   369篇
现状与发展   2篇
预防医学   139篇
眼科学   79篇
药学   113篇
  2篇
中国医学   30篇
肿瘤学   258篇
  2024年   9篇
  2023年   129篇
  2022年   210篇
  2021年   284篇
  2020年   270篇
  2019年   322篇
  2018年   260篇
  2017年   256篇
  2016年   267篇
  2015年   231篇
  2014年   451篇
  2013年   408篇
  2012年   254篇
  2011年   355篇
  2010年   292篇
  2009年   301篇
  2008年   279篇
  2007年   280篇
  2006年   236篇
  2005年   225篇
  2004年   185篇
  2003年   163篇
  2002年   149篇
  2001年   144篇
  2000年   138篇
  1999年   122篇
  1998年   152篇
  1997年   122篇
  1996年   128篇
  1995年   95篇
  1994年   74篇
  1993年   101篇
  1992年   93篇
  1991年   77篇
  1990年   43篇
  1989年   47篇
  1988年   45篇
  1987年   44篇
  1986年   41篇
  1985年   55篇
  1984年   45篇
  1983年   36篇
  1982年   34篇
  1981年   42篇
  1980年   41篇
  1979年   26篇
  1978年   24篇
  1977年   20篇
  1976年   10篇
  1973年   6篇
排序方式: 共有7635条查询结果,搜索用时 578 毫秒
21.
Neuroimaging of Focal Cortical Dysplasia   总被引:3,自引:0,他引:3  
Focal cortical dysplasia (FCD) is a common cause of pharmacoresistant epilepsy that is amenable to surgical resective treatment. The identification of structural FCD by magnetic resonance imaging (MRI) can contribute to the detection of the epileptogenic zone and improve the outcome of epilepsy surgery. MR epilepsy protocols that include specific T1 and T2 weighted, and fluid-attenuated inversion recovery (FLAIR) sequences give complementary information about the characteristic imaging features of FCD; focal cortical thickening, blurring of the gray-white junction, high FLAIR signal, and gyral anatomical abnormalities. Novel imaging techniques such as magnetic resonance spectroscopy (MRS), magnetization transfer imaging (MTI), and diffusion tensor imaging (DTI) can improve the sensitivity of MR to localize the anatomical lesion. Functional/metabolic techniques such as positron emission tomography (PET), ictal subtraction single photon emission computed tomography (SPECT), functional MRI (fMRI), and magnetic source imaging (MSI) have the potential to visualize the metabolic, vascular, and epileptogenic properties of the FCD lesion, respectively. Identification of eloquent areas of cortex, to assist in the surgical resection plan, can be obtained non-invasively through the use of fMRI and MSI. Although a significant number of FCD lesions remain unidentified using current neuroimaging techniques, future advances should result in the identification of an increasing number of these cortical malformations.  相似文献   
22.
目的 探讨骨纤维异常增殖症起始部位与生长方式。分析其影像学特异性征象。方法 对13例经手术病理证实的骨纤维异常增殖症之CT/MR影像进行回顾性分析并作献复习。结果 病灶成像以纤维组织为主多局限于皮质内生长;病灶成份以编织骨为主。易穿入髓腔弥漫生长。结论 病变起始骨皮质,按病理组织学不同成份。决定其生长方式。CT/MR影像显示起始部位与发展趋势,具有特殊定性诊断价值。  相似文献   
23.
Twenty-two percutaneous transluminal balloon valvuloplasty procedures were performed on 21 patients with congenital pulmonary valve stenosis. The peak systolic pressure gradient was immediately reduced from 79.1 +/- 7.4 to 22.2 +/- 1.8 mmHg, (P less than 0.0001) and follow-up cardiac catheterization at 5.3 +/- 0.4 months in 19 patients revealed no further significant change in gradient (23.5 +/- 3.2 mmHg). The best results were obtained when balloons larger than the pulmonary annulus were used, i.e. an immediate residual transvalvular gradient of 22.0 +/- 2.2 mmHg with a balloon/annulus ratio greater than 1, as opposed to 44.2 +/- 5.4 with a balloon/annulus ratio = 1 (P less than 0.001). The angiographically determined cusp thickness of the stenotic pulmonary valves was significantly greater than that of the control group of 24 patients without pulmonary valve stenosis (1.21 +/- 0.09 vs 0.59 +/- 0.02 mmHg, P less than 0.00001). The relationship between this parameter and the residual transvalvular gradient at follow-up was found to be significant (r = 0.77, P less than 0.001). It is concluded that balloon size is a determinant factor in achieving good results with percutaneous balloon valvuloplasty although cusp thickness, a factor to which scant regard has hitherto been paid, also plays a significant role in the residual transvalvular gradient measured at follow-up.  相似文献   
24.
The major forms of lung pathology in the perinatal period are reviewed with emphasis on disturbances of growth and maturation. Lung hypoplasia results from impairment in the physiological control of lung growth during the fetal period. It is more common than organogenetic defects which are discussed only briefly. Hyaline membrane disease is now seldom seen in a pure form due to improvements in perinatal care. However, its complications and sequelae such as interstitial emphysema, pneumothorax and bronchopulmonary dysplasia are encountered more frequently. In addition, a wide variety of pathological processes may localize to, or be expressed in, the lung of the newborn, notably asphyxial changes, persistent pulmonary hypertension, haemorrhage and infection.  相似文献   
25.
本文通过对228例各种类型胃粘膜上皮异型增生的病理切片的复查,发现并详细地描述了不同类型异型增生腺管和上皮细胞癌变的初发点(Start point)。其形态有的是从再生腺管的腺颈部或底部以“发芽”形式,向质内浸润并分枝生长;有的是从再生腺管基底膜向侧方的间质浸润。从再生的胃上皮型异型腺管所出现的癌变多为低分化型腺癌;从肠上皮型异型腺管所发生的癌变则为高分化型腺癌。强调了胃粘膜再生性异型增生有些具有癌前性质。  相似文献   
26.
应用自显像技术对内镜活检胃肠化生和异型增生上皮进行~3H-TdR 标志,观察标记率及增殖带的变化。异型增生标记率(18.50~19.21)及大肠化生标记率(18.57)较高,与胃癌(19.32)相似,并且其增殖带向粘膜表面及深部移动。这种细胞动力学的变化可能是胃癌癌前病变的基础。  相似文献   
27.
Moderate increases in ``classical' biochemical markers of bone turnover have been described only in some patients with Camurati–Engelmann disease. However, the determination of the following ``new' markers has not been previously performed: serum osteocalcin (BGP), bone alkaline phosphatase (BAP), carboxyterminal propeptide of type I procollagen (PICP), aminoterminal propeptide of type I procollagen (PINP), tartrate-resistant acid phosphatase (TRAP), telopeptide carboxyterminal of type I collagen (ICTP), urinary pyridinoline (PYR), crosslinked N-telopeptides of type I collagen (NTX), and Crosslaps (CL). Such a determination may improve the evaluation of the disease activity. To evaluate the usefulness of biochemical markers of bone turnover reflecting Camurati–Engelmann disease activity we measured the levels of all these markers in four affected patients. The results were compared with bone scintigraphic indices of disease activity. Except for PICP and TRAP, bone formation and resorption markers were abnormal in all patients and were related to bone scan indices of disease activity. Among the markers of bone formation PINP, BAP, and BGP showed the highest values, whereas NTX and CL were the most sensitive markers of bone resorption. These results suggest that the determination of NTX or CL, and PINP or either BAP and BGP, associated with bone scan evaluation, provides the best assessment of Camurati–Engelmann disease activity. Received: 14 June 1996 / Accepted: 31 December 1996  相似文献   
28.
Histological examination of the deciduous teeth in two cases of segmental odontomaxillary dysplasia (SOMD) showed fibrous enlargement of the pulps, an irregular pulp/dentine interface displaying many pseudoinclusions and pulp stones. There were tubular defects in the coronal dentine from pulp horn to cusp tip, an irregular tubular structure to the circumpulpal dentine of the apical half, a focally deficient odontoblast layer and widespread external resorption. Together with the clinical features of unilateral maxillary enlargement, upper alveolar expansion in the distal segment, increased spacing and delayed eruption of the deciduous molars and absence of premolar teeth, these histological appearances allow distinction of this condition from fibrous dysplasia (FD), segmental hemifacial hypertrophy (SHH) and regional odontodysplasia (ROD).  相似文献   
29.
We describe a 28-year-old white Caucasian man displaying many of the physical signs of ectodermal dysplasia (ED). An unusual finding was his presentation with xerostomia. Salivary gland imaging techniques revealed aplasia of both submandibular salivary glands and relatively small parotids. The case highlights that hypoplasia and aplasia of exocrine glands could be rare features of ED. In the management of ED, early detection of xerostomia is important to limit any potential damage to the already hypodontic dentition.  相似文献   
30.
用嗜银染色技术对34例良性胃溃疡、40例胃粘膜异型增生、46例胃腺癌组织石蜡切片中的核仁组成相关蛋白(AgNOR)进行研究,25例正常胃粘膜组织作对照。发现对照组、良性溃疡组,异型增生组和腺癌组的细胞核AgNOR平均计数差异有显著性(P<0.01)。恶性细胞中AgNOR的体积、形状及在细胞核内的位置也不相同。作者认为此法有助于区别胃的良性和恶性病变。  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