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   10874篇
  免费   561篇
  国内免费   104篇
耳鼻咽喉   103篇
儿科学   250篇
妇产科学   108篇
基础医学   1071篇
口腔科学   161篇
临床医学   752篇
内科学   3011篇
皮肤病学   150篇
神经病学   655篇
特种医学   380篇
外科学   2172篇
综合类   68篇
预防医学   234篇
眼科学   159篇
药学   712篇
中国医学   17篇
肿瘤学   1536篇
  2023年   87篇
  2022年   170篇
  2021年   302篇
  2020年   187篇
  2019年   232篇
  2018年   269篇
  2017年   244篇
  2016年   283篇
  2015年   309篇
  2014年   361篇
  2013年   436篇
  2012年   731篇
  2011年   760篇
  2010年   440篇
  2009年   361篇
  2008年   594篇
  2007年   637篇
  2006年   664篇
  2005年   680篇
  2004年   649篇
  2003年   645篇
  2002年   635篇
  2001年   163篇
  2000年   156篇
  1999年   169篇
  1998年   117篇
  1997年   97篇
  1996年   91篇
  1995年   78篇
  1994年   84篇
  1993年   74篇
  1992年   83篇
  1991年   104篇
  1990年   66篇
  1989年   83篇
  1988年   82篇
  1987年   52篇
  1986年   45篇
  1985年   34篇
  1984年   32篇
  1983年   35篇
  1982年   16篇
  1980年   13篇
  1979年   31篇
  1978年   13篇
  1976年   11篇
  1973年   12篇
  1971年   16篇
  1969年   14篇
  1966年   17篇
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
41.
Mice homozygous for klotho gene deletion are well established aging models as they mimic certain aspects of human senescence e.g. osteoporosis. Induced senescence may affect cellular functions and alter the histological properties of the extracellular matrices. The present study examined the histological and ultrastructural features of osteocytes and the surrounding bone matrix in klotho-deficient mice. As expected, osteoblasts showed a flattened shape with a weak immunoreactivity for alkaline phosphatase, and the bone matrix contained many empty osteocytic lacunae. The walls of both normal and empty lacunae were intensely immunopositive for osteopontin and dentin matrix protein-1, but featured an inconsistent immunoreactivity for osteocalcin and type I collagen. Not surprisingly, TUNEL-positivity, indicative of apoptosis, was found in many osteoblasts, osteocytes, and bone marrow cells of the klotho-deficient mice. In transmission electron microscopy, an amorphous matrix containing non-collagenous organic materials was recognizable around osteoblasts and in the osteocytic lacunae. Some osteoblasts on the bone surface featured these amorphous materials in vacuoles associated with their trans-Golgi network, indicating that, under klotho-deficient conditions, they synthesize and secrete the non-collagenous structures. Some osteocytes displayed pyknosis or degenerative traits. Thus, our findings provide histological evidence that klotho gene deletion influences the spatial distribution of osteocytes and the synthesis of bone matrix proteins in addition to the accelerated aging of bone cells.  相似文献   
42.
BackgroundMethotrexate (MTX) or mycophenolate mofetil with tacrolimus (TAC) is used for graft-vs-host disease (GVHD) prophylaxis in unrelated cord blood transplantation (CBT). However, there is no consensus regimen for GVHD prophylaxis in CBT. We aimed to assess the efficacy and feasibility of minimum-dose, short-term MTX (MS-MTX) for GVHD prophylaxis in CBT.MethodsWe retrospectively evaluated 35 consecutive adult patients who underwent CBT and received MS-MTX (6 mg/m2 day 1; 3 mg/m2 days 3 and 6, intravenously) with TAC for GVHD prophylaxis in our hospital between 2015 and 2019. Transplantation outcomes with respect to time to hematopoietic recovery, engraftment, incidence and severity of GVHD, adverse events, relapse, nonrelapse mortality (NRM), and overall survival were evaluated.ResultsThe median time to neutrophil, platelet, and reticulocyte recovery was 22, 38, and 32 days, respectively. Cumulative neutrophil engraftment was 91.4%. After a median 3.2-year follow-up, the 2-year overall survival was 64.3%. The 2-year cumulative incidence of relapse and NRM was 20.4% and 14.9%, respectively. The 100-day cumulative incidence of grade II-IV acute GVHD and 2-year cumulative incidence of chronic GVHD were 28.6% and 36.6%, respectively. No grade IV acute GVHD was observed. Sixteen patients experienced oral mucositis and/or pharyngeal pain (46%; grades 1-2, n = 15; grade 3 pharyngeal pain, n = 1). No patients suffered from human herpesvirus 6 encephalitis/myelitis.ConclusionsMS-MTX with TAC is feasible and safe and yields lower rates of severe oropharyngeal mucositis and human herpesvirus 6 encephalitis/myelitis without increasing GVHD, graft failure, relapse, or NRM.  相似文献   
43.
ObjectivesWe aimed to evaluate the effect of frailty on health-related quality-of-life (HRQOL) and lower urinary symptoms (LUTS) following robot-assisted radical prostatectomy (RARP) in patients with prostate cancer (CaP).Materials and MethodsWe longitudinally evaluated geriatric 8 (G8), HRQOL, and LUTS for 12 months in 118 patients with RARP from January 2017 to April 2020. Patients were divided into frail (G8 ≤14) and nonfrail (G8 >14) groups. We compared the effect of frailty on HRQOL and LUTS between the frail and nonfrail groups before and 12 months after RARP.ResultsThe median age of patients was 68 years. The number of patients in the frail and nonfrail groups were 41 and 77, respectively. No significant difference in patients’ background was observed between the groups, except for the presence of cardiovascular disease (22% vs. 7.8%, P = 0.041). There was no significant difference in HRQOLs and LUTS between the groups at baseline. Similarly, HRQOLs, LUTS, and pad-free continence rates were not significantly different between the groups at 12 months after RARP. In the nonfrail group, LUTS at 12 months following RARP significantly improved compared to those at the baseline, but it did not significantly improve in the frail group. Multivariable logistic regression analysis demonstrated that frailty was not significantly associated with LUTS worsening.ConclusionsFrailty was not significantly associated with the worsening of HRQOL, LUTS, and pad-free continence rates in patients treated with RARP.  相似文献   
44.
45.
To elucidate the necessity of pyloroplasty for the gastric tube through the posterior mediastinum in esophageal surgery, gastric emptying and duodenogastric reflux (DGR) were evaluated in 16 cases undergoing an anterior pylorectomy (group P) and in 16 cases treated by the finger bougie method (group F). First, the obstruction and reflux symptoms were examined based on a patient questionnaire using a brief scoring system. The median value of the symptom score showed the patients in P to have more symptoms than those in F; however, the difference was not significant (8.0 vs 6.0). Secondly, the swallowed Tc O4 (85 MBq) was counted using a gamma camera at three sites on the sternal bone in the upright position based on a gastric transit scintigram. Both the descending time of the RI peak and the clearance rates were similar between the two groups. Thirdly, intragastric 24-h pH monitoring was carried out. Antimony pH sensors were anchored 5 and 15 cm below the esophagogastrostomy. We could not find any difference between the two groups in both the % time pH>4 and %time pH>7. These findings thus revealed no big difference between groups P and F. The finger bougie method to drain the vagotomized posterior mediastinal stomach was found to achieve results similar to conventional pyloroplasty, while it was also simpler and safer.  相似文献   
46.
22-Oxacalcitriol ameliorates high-turnover bone and marked osteitis fibrosa in rats with slowly progressive nephritis. BACKGROUND: 22-Oxacalcitriol (OCT) is a unique vitamin D analogue with less calcemic activity than calcitriol, and it effectively suppresses parathyroid hormone (PTH) secretion in uremic rats. This study was performed to examine the long-term effect of intravenously administered OCT on high-turnover bone disease in model rats of slowly progressive renal failure. METHODS: Slowly progressive renal failure rats were made by a single injection of glycopeptide isolated from rat renal cortical tissues. At 250 days, glycopeptide-induced nephritis (GN) rats were divided into three groups with the same levels of serum creatinine and PTH, and they received either OCT (0.03 or 0.15 microg/kg body wt) or vehicle given intravenously three times per week for 15 weeks. RESULTS: Renal function of GN rats deteriorated very slowly but progressively, as assessed by the increase of serum creatinine concentration. At sacrifice, serum PTH levels, bone formation markers, bone resorption markers, and fibrosis volume were significantly elevated in vehicle-treated GN rats compared with those of sham-operated rats, suggesting the development of high-turnover bone disease with osteitis fibrosa. In contrast, in the GN-OCT 0.15 microg/kg group, these high PTH levels and high-turnover bone and fibrosis were significantly decreased. Such amelioration of bone abnormalities by OCT was not accompanied by either hypercalcemia or further deterioration of renal function. CONCLUSIONS: These data indicate that OCT may be a useful and safe agent not only for the suppression of PTH, but also for the amelioration of osteitis fibrosa and high-turnover bone without causing hypercalcemia in chronic dialysis patients.  相似文献   
47.
The process of the development of the intracranial vessels was studied by means of immunohistochemical analysis of factor VIII in normal and exencephalic chick fetuses. The results revealed that the development of blood vessels in exencephalic brain was far advanced beyond the norm, with intense immunoreactivity to factor VIII on postincubation day 16 exceeding that on day 21 in normal controls. Compared with results regarding the direction of the overgrowth in the neuronal maturation process in the previous study using the chick exencephaly model, the findings of overmatured blood vessels were compatible with NSE- and somatostatin-positive elements that appeared especially in the overgrowth foci. The results of the present study suggested the pathogenic development of the area cerebrovasculosa in the neural placode as a phenomenon consequent upon hypervascularization in response to neuronal overgrowth, as seen in human cases of exencephaly or anencephaly. We emphasize the significance of this specific phenomenon in the development of the fetal central nervous system, namely neurovascular developmental interaction.  相似文献   
48.
49.
To improve low-pitched voices in cases with polypoid vocal cords, YAG laser irradiation combined with a mucosal suturing technique was attempted in 9 female cases with severe polypoid changes in their vocal cords. A YAG laser beam (5 to 10 W) was used to irradiate the upper surface of the polypoid vocal cord. The polypoid content of the cord was gradually coagulated, and the free edge of the cord appeared to slide up toward the burned area. The polypoid content was then removed and squeezed through an open wound made in the burned area using a conventional method. Bleeding was successfully controlled using the laser. After the excessive mucosal margin was trimmed and the contour of the vocal cord was adjusted, the wound was closed by 7-0 monofilament absorbable suture. Suturing was relatively easy because the mucosal edge was also coagulated. Postoperative evaluations of voice quality revealed an improvement in the GRBAS scale of voice quality as well as an elevation in voice pitch and an upwards shift in the voice range in all cases.  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