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   8281篇
  免费   589篇
  国内免费   90篇
耳鼻咽喉   64篇
儿科学   206篇
妇产科学   395篇
基础医学   926篇
口腔科学   187篇
临床医学   1014篇
内科学   1658篇
皮肤病学   75篇
神经病学   710篇
特种医学   270篇
外科学   1085篇
综合类   226篇
一般理论   4篇
预防医学   461篇
眼科学   179篇
药学   701篇
中国医学   83篇
肿瘤学   716篇
  2023年   35篇
  2022年   69篇
  2021年   178篇
  2020年   104篇
  2019年   176篇
  2018年   209篇
  2017年   175篇
  2016年   174篇
  2015年   239篇
  2014年   281篇
  2013年   374篇
  2012年   544篇
  2011年   616篇
  2010年   405篇
  2009年   341篇
  2008年   500篇
  2007年   498篇
  2006年   516篇
  2005年   454篇
  2004年   398篇
  2003年   330篇
  2002年   292篇
  2001年   270篇
  2000年   226篇
  1999年   192篇
  1998年   72篇
  1997年   69篇
  1996年   66篇
  1995年   49篇
  1994年   37篇
  1993年   39篇
  1992年   112篇
  1991年   117篇
  1990年   96篇
  1989年   72篇
  1988年   71篇
  1987年   73篇
  1986年   47篇
  1985年   41篇
  1984年   33篇
  1983年   35篇
  1981年   24篇
  1980年   18篇
  1979年   27篇
  1978年   33篇
  1977年   18篇
  1975年   18篇
  1974年   26篇
  1973年   17篇
  1968年   18篇
排序方式: 共有8960条查询结果,搜索用时 515 毫秒
31.
We present two patients with angulated, proximal left circumflex lesions, one a chronic total occlusion and one an acute subtotal occlusion. In both cases, use of the deflectable tip Venture Catheter (Velocimed, Minneapolis, MN) facilitated guide wire passage and successful percutaneous coronary intervention (PCI) after prior attempts at guide wire passage with standard wires were unsuccessful.  相似文献   
32.
33.
PURPOSE: This study was an analysis of the soft and hard tissue changes of the facial profile after bilateral sagittal splitting osteotomy for mandibular setback of Taiwanese patients. PATIENTS AND METHODS: We collected pre- and postsurgical lateral cephalographs of 64 patients (28 males, 36 females) with skeletal Class III malocclusion who received combined orthodontic-surgical treatment with bilateral sagittal splitting osteotomy mandibular setback at Taipei Veterans General Hospital between 1994 and 2000. Nineteen cephalometric parameters of (14 linear, 4 angular, and the BS index) soft and hard tissues were measured at 1 week before treatment, and 2 months and 1 year after surgery, and analyzed by paired t test. RESULTS: Mean patient age was 20.0 +/- 1.6 years. The patients underwent an average of 7 mm mandibular setback at the osseous pogonion (Pog). Average setbacks at Pog and soft tissue pogonion (pog) were 5.54 mm and 4.85 mm, respectively, at 1 year after surgery. The setback ratio of Pog/pog was 1:0.88. The hard tissue relapse at Pog was 21% at 1 year after surgery. Improvement in prognathic profile was demonstrated by significant changes in the positions of Pog and pog, ANB angle, the distance from lower lip to esthetic line (E-L lip), and the BS index after surgery. However, compared with parameters obtained from a normal Taiwanese population, the cephalometric data of Pog, pog, and BS index still indicated mild prognathism. CONCLUSION: Although mandibular prognathism could be grossly improved by bilateral sagittal splitting osteotomy mandibular setback, a significant amount of relapse occurred within 1 year after surgery. The extent of the postoperatively preserved features showing mandibular prognathism should be a concern for both patients and physicians.  相似文献   
34.
S Y Wang  K L Mak  L Y Chen  M P Chou    C K Ho 《Immunology》1992,77(2):298-303
Human blood mononuclear cells from normal adults were collected after density-cut centrifugation and monocytes were then isolated by removal of lymphocytes using the techniques of E-rosetting and cell adhesion. The purified monocytes were further analysed by velocity sedimentation, and two distinct subpopulations with different cell sizes were obtained. The larger monocytes were 17.0 +/- 1.8 microns in diameter with a mean sedimentation rate (SR) of 7.0 +/- 0.6 mm/hr, while the smaller monocytes were 9.5 +/- 0.8 microns in size and 4.1 +/- 0.2 mm/hr in SR. The population ratio of larger:smaller cells was approximately 2:1 (66 +/- 2.8%:34 +/- 1.6%). Both cell populations exhibited a high positive rate (> 98%) in both the non-specific esterase and the peroxidase stain. However, the larger cells had much higher phagocytic activity than the smaller ones. Furthermore, the expression of monocyte-associated antigens was also different between these two subpopulations. Thus, while most of the larger monocytes (98%) could be recognized by monoclonal antibodies MY7 and OKM1, only some (35 and 61%, respectively) of the smaller monocytes could react with those antibodies. In addition, the larger monocytes secreted a significant amount of monokines including interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha) and prostaglandin E2 (PGE2) and their production increased in proportion to the level of stimulation by bacterial lipopolysaccharide (LPS), whereas the production of monokines by the smaller monocytes remained at low levels and did not respond to LPS stimulation. These results reveal the existence of phenotypic and functional heterogeneity in human blood monocytes.  相似文献   
35.
The ability to cluster different perfusion compartments in the brain is critical for analyzing brain perfusion. This study presents a method based on a mixture of multivariate Gaussians (MoMG) and the expectation-maximization (EM) algorithm to dissect various perfusion compartments from dynamic susceptibility contrast (DSC) MR images so that each compartment comprises pixels of similar signal-time curves. This EM-based method provides an objective way to 1) delineate an area to serve as the in-plane arterial input function (AIF) of the feeding artery for adjacent tissues to better quantify the relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), and mean transit time (MTT); 2) demarcate regions with abnormal perfusion derangement to facilitate diagnosis; and 3) obtain parametric maps with supplementary information, such as temporal scenarios and recirculation of contrast agent. Results from normal subjects show that perfusion cascade manifests (in order of appearance) the arteries, gray matter (GM), white matter (WM), veins and sinuses, and choroid plexus mixed with cerebrospinal fluid (CSF). The averaged rCBV, rCBF, and MTT ratios between GM and WM are in good agreement with those in the literature. Results from a patient with cerebral arteriovenous malformation (CAVM) showed distinct spatiotemporal characteristics between perfusion patterns, which allowed differentiation between pathological and nonpathological areas.  相似文献   
36.
We report the case of a 31-year-old woman with an androgen-producing sclerosing stromal tumor found during the eighth week of gestation in association with ascites and elevated serum androgen and cancer antigen (CA)-125 levels. The combined features of ascites, elevated serum androgen and elevated CA-125 in association with this rare type of ovarian tumor is unusual. Surgical removal of the tumor resulted in relief of symptoms, resolution of ascites, and decreases in serum androgen and CA-125 levels. The pregnancy was uneventful.  相似文献   
37.
Intestinal schistosomiasis japonica: CT-pathologic correlation   总被引:1,自引:0,他引:1  
  相似文献   
38.
We examined the relationship between testosterone levels, violent dreams, and REM sleep behavior disorder (RBD) in 31 men with Parkinson's disease (PD): 12 with clinical RBD and 19 without. All PD patients with clinical RBD experienced violent dreams, but none of the 19 non-RBD patients reported violent dreams. While dream content appears to be more aggressive in PD patients with clinical RBD, the presence of violent dreams or clinical RBD is not associated with testosterone levels in men with PD.  相似文献   
39.
BACKGROUND AND PURPOSE: Etanercept (Enbrel), a recombinant tumor necrosis factor receptor fusion protein, has been shown to be effective in the treatment of patients with rheumatoid arthritis (RA). The purpose of this study was to compare the efficacy and safety of etanercept in combination with methotrexate (MTX) and MTX alone in Taiwanese patients with active RA. METHODS: In this double-blind study, 58 patients with active RA who were maintained on MTX therapy at a stable dose of 12.5 to 20 mg per week for 4 weeks were randomized to receive either etanercept 25 mg (n = 29) or placebo (n = 29) by subcutaneous injection twice weekly over a period of 12 weeks. The primary endpoint was the reduction of tender and swollen joint counts by 20% (ACR 20), 50% (ACR 50), and 70% (ACR 70) as determined by the American College of Rheumatology criteria at the 12th week. RESULTS: The addition of etanercept to MTX resulted in a greater reduction in the number of tender (7.00 vs 2.45, p = 0.012) and swollen joints (8.55 vs 3.86, p = 0.017), and in serum levels of C-reactive protein (1.26 mg/dL vs 0.45 mg/dL, p = 0.014) compared to MTX alone after 12 weeks of therapy. In addition, the global assessment of disease activity by both physicians and patients, duration of morning stiffness, pain visual analog scale score, and Health Assessment Questionnaire were all improved by etanercept plus MTX therapy. Results for the overall improvement in disease activity assessed by ACR 20 (90% vs 34%), ACR 50 (66% vs 10%) and ACR 70 (24% vs 0%) all favored the etanercept plus MTX group. However, the adverse events were comparable between the 2 treatment groups. CONCLUSION: Etanercept in combination with MTX was well tolerated and provided significantly more clinical benefit than MTX alone in Taiwanese patients with active RA.  相似文献   
40.
Occult congenital temporal lobe encephalocele has rarely been reported in association with medically intractable complex partial seizures. The four previously reported cases were unsuspected preoperatively. We present the case of an 18-year-old woman with intractable complex partial seizures since age 13. Seizure onset was electrically localized to the right temporal lobe. Preoperative neuroimaging studies revealed a middle fossa defect and inferior herniation of the right temporal lobe. Pathologic examination of the resected encephalocele revealed prominent features of meningoangiomatosis. We believe this to be the first case of temporal lobe encephalocele and epilepsy to be diagnosed preoperatively, and the first case also to be associated with meningoangiomatosis. The relevant literature on meningoangiomatosis and on temporal lobe encephalocele as a cause of epilepsy is reviewed.  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