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   7829篇
  免费   376篇
  国内免费   92篇
耳鼻咽喉   59篇
儿科学   219篇
妇产科学   166篇
基础医学   898篇
口腔科学   143篇
临床医学   589篇
内科学   2069篇
皮肤病学   219篇
神经病学   771篇
特种医学   441篇
外科学   1293篇
综合类   22篇
预防医学   342篇
眼科学   68篇
药学   399篇
中国医学   7篇
肿瘤学   592篇
  2024年   10篇
  2023年   74篇
  2022年   154篇
  2021年   255篇
  2020年   140篇
  2019年   177篇
  2018年   215篇
  2017年   156篇
  2016年   207篇
  2015年   237篇
  2014年   293篇
  2013年   389篇
  2012年   561篇
  2011年   600篇
  2010年   345篇
  2009年   315篇
  2008年   490篇
  2007年   488篇
  2006年   488篇
  2005年   500篇
  2004年   461篇
  2003年   397篇
  2002年   337篇
  2001年   76篇
  2000年   66篇
  1999年   67篇
  1998年   64篇
  1997年   64篇
  1996年   49篇
  1995年   49篇
  1994年   43篇
  1993年   37篇
  1992年   41篇
  1991年   35篇
  1990年   33篇
  1989年   29篇
  1988年   38篇
  1987年   32篇
  1986年   30篇
  1985年   31篇
  1984年   23篇
  1983年   19篇
  1982年   18篇
  1981年   11篇
  1979年   18篇
  1977年   9篇
  1976年   9篇
  1974年   10篇
  1967年   9篇
  1966年   9篇
排序方式: 共有8297条查询结果,搜索用时 8 毫秒
41.
The aim of this study was to investigate the usefulness of contrast-enhanced harmonic power Doppler ultrasound (US) for the detection of residual viable hepatocellular carcinoma (HCC) after treatment with transcatheter arterial chemoembolization (TACE). Forty-seven patients with 68 HCC lesions 1.8–9.5 cm in diameter (mean ± SD 4.3 ± 1.7 cm) underwent contrast-enhanced power Doppler US, in the harmonic mode, before and after treatment with TACE. Unenhanced spiral CT and contrast-enhanced dynamic MR imaging were also performed to help establish the outcome of therapy. Before treatment, intratumoral blood flow signals were detected at contrast-enhanced harmonic power Doppler US in 65 (95 %) of 68 lesions. After TACE, flow signals were no longer detectable in 22 of these 65 lesions, which showed complete response at spiral CT and dynamic MR imaging. In 38 (88 %) of the 43 lesions with partial response, intratumoral flow signals were still identified at contrast-enhanced harmonic power Doppler US. Twenty-eight of these 38 lesions underwent additional treatment with percutaneous ethanol injection (PEI) using contrast-enhanced harmonic power Doppler US guidance. Complete response was seen after PEI in 23 of 28 lesions. Contrast-enhanced harmonic power Doppler US proved useful for assessing the therapeutic effect of TACE on HCC and for guiding additional treatment with PEI in cases of partial response. Received: 25 January 2000; Revised: 21 April 2000; Accepted: 25 April 2000  相似文献   
42.
High-resolution magnetic resonance and volume rendering of the labyrinth   总被引:4,自引:0,他引:4  
Our aim was to verify the feasibility of volume rendering (VR) of high-resolution magnetic resonance (HR-MR) data sets of the labyrinth. We retrospectively reviewed the HR-MR data sets of 16 consecutive patients with no MR evidence of labyrinthine pathology. High-resolution MR data sets were obtained by means of a 3D T2-weighted FSE sequence with the use of a 3-in. circular surface coil for signal reception, and processed with a high-end workstation. Two reviewers performed separately VR of the labyrinth by selecting the signal intensity interval for attribution of opacity and transparency. Concerning the time taken for definition of the volume of interest, the two observers needed, respectively, 28.9 and 33.1 min (SD ± 8.7–9.5 min), whereas the time taken for VR was respectively, 26 and 33.2 min (SD ± 8.8–8.9 min). Concerning the selection of the signal intensity interval, the two observers had, respectively, 86.4 and 88.7 mean lower threshold (SD ± 34.5–33.5), 488.9 and 495.4 mean upper threshold (SD ± 56.3–53.8). In our experience, we have found VR of HR-MR to offer a reliable and reproducible technique for producing 3D representations of the labyrinth. The VR algorithms use all data within the imaging volume and optimize the dynamic range ascribed to the object being visualized. Received: 9 October 1998; Revised: 14 January 1999; Accepted: 30 June 1999  相似文献   
43.
Free-radical formation may play a role in postoperative complications of phacoemulsification (e.g., corneal endothelium damage from mechanical injury). The present experiments were aimed at investigating whether different molecular weight ranges (2000-2600, 2600-3200, or 3200-3800 kDa) of hyaluronan may influence free radical formation, corneal endothelium damage, and inflammation parameters after phacoemulsification in the rabbit eye. The viscoelastic substance was injected in the anterior chamber of rabbits' eyes before phacoemulsification, at a 2.5% concentration. The formation of free radicals was determined by adding luminol to the irrigation media and measuring the chemoluminescence in eyes. The corneal endothelial damage was evaluated by measuring the corneal central thickness by pachimetry. The inflammation parameters were measured by calculation in aqueous humor of peak levels of leukocytes and prostaglandin E(2) (PGE(2)) and evaluation in uveal tissue of myeloperoxidase activity. Hyaluronan decreased by about 58-60% free-radical formation during phacoemulsification, reduced by about 76-80% modifications in mean corneal thickness and by about 54-61% the corneal endothelial cell loss in all molecular weight ranges used. No difference was found among various molecular weight ranges. The highest molecular weight range showed to be more potent than the lowest range for reduced number of inflammation cells and level of PGE(2) in aqueous humor. Thus, hyaluronan reduces free-radical formation, exerts protection on the corneal endothelium and exerts anti-inflammation properties after phacoemulsification in rabbits. The latter effect seems to depend on the molecular weight of the substance.  相似文献   
44.
Sports medicine physicians are not exempt from the ethical challenges of medical practice merely because their patients are robust and healthy. In fact, precisely because the patients with sports injuries are so healthy the moral issues remain subtle. Many ethical issues in sports medicine come about because the traditional relationship between doctor and patient is altered or absent. In the current review, several routine topics in biomedical ethics, including doctor and patient confidentiality, informed consent, the care of minors, medical advertising and use of innovative treatments, will be studied from the sports medicine perspective. Hypothetical case histories will be presented, along with an analysis of the underlying ethical issues. The goal of this analysis is not to offer answers to these moral questions, but to increase awareness and promote contemplation of the correct course of action.  相似文献   
45.
Mucoepidermoid Carcinoma (MEC) it can origin from a mandibular odontogenic cyst. We report the case of a 63‐year‐old man with MEC of the right retromolar trigonum of the mandibula. We performed a wide mandibular excision and immediate reconstruction with a fibula bone free flap.  相似文献   
46.
47.
IntroductionSeveral functional neuroimaging studies on healthy controls and patients with migraine with aura have shown that the activation of functional networks during visual stimulation is not restricted to the striate system, but also includes several extrastriate networks.MethodsBefore and after 4 min of visual stimulation with a checkerboard pattern, we collected functional MRI in 21 migraine with aura (MwA) patients and 18 healthy subjects (HS). For each recording session, we identified independent resting-state networks in each group and correlated network connection strength changes with clinical disease features.ResultsBefore visual stimulation, we found reduced connectivity between the default mode network and the left dorsal attention system (DAS) in MwA patients compared to HS. In HS, visual stimulation increases functional connectivity between the independent components of the bilateral DAS and the executive control network (ECN). In MwA, visual stimulation significantly improved functional connectivity between the independent component pairs salience network and DAS, and between DAS and ECN. The ECN Z-scores after visual stimulation were negatively related to the monthly frequency of aura.ConclusionsIn individuals with MwA, 4 min of visual stimulation had stronger cognitive impact than in healthy people. A higher frequency of aura may lead to a diminished ability to obtain cognitive resources to cope with transitory but important events like aura-related focal neurological symptoms.  相似文献   
48.
49.
BACKGROUND: Endometrial ossification is a rare disease. More than 80% of cases occur after pregnancy, but it has been observed in patients with a history of endometritis, dilation and curettage, and metabolic disorders. CASE: A 42-year-old woman presented with osseous metaplasia of both the endometrium and ovaries. At laparoscopy both adnexa were covered with adhesions and were adherent to the posterior wall of the uterus. Following adhesiolysis, calcified nodules were removed from both ovaries with biopsy forceps. Endometrial bone tissue was removed by hysteroscopic resection. CONCLUSION: To our knowledge, this is the first reported case of osseous metaplasia of both the endometrium and ovaries since all cases described to date in the literature involved only the uterine cavity. Conservative management with endoscopic surgery is effective.  相似文献   
50.
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