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   3859篇
  免费   282篇
  国内免费   14篇
耳鼻咽喉   20篇
儿科学   172篇
妇产科学   28篇
基础医学   600篇
口腔科学   88篇
临床医学   253篇
内科学   1002篇
皮肤病学   205篇
神经病学   274篇
特种医学   84篇
外科学   677篇
综合类   21篇
预防医学   93篇
眼科学   48篇
药学   212篇
中国医学   16篇
肿瘤学   362篇
  2023年   28篇
  2022年   50篇
  2021年   75篇
  2020年   44篇
  2019年   68篇
  2018年   102篇
  2017年   92篇
  2016年   76篇
  2015年   96篇
  2014年   80篇
  2013年   129篇
  2012年   210篇
  2011年   230篇
  2010年   106篇
  2009年   103篇
  2008年   202篇
  2007年   218篇
  2006年   195篇
  2005年   211篇
  2004年   183篇
  2003年   154篇
  2002年   183篇
  2001年   92篇
  2000年   91篇
  1999年   81篇
  1998年   52篇
  1997年   30篇
  1996年   33篇
  1995年   40篇
  1994年   31篇
  1993年   40篇
  1992年   89篇
  1991年   82篇
  1990年   62篇
  1989年   56篇
  1988年   47篇
  1987年   55篇
  1986年   51篇
  1985年   44篇
  1984年   20篇
  1983年   23篇
  1982年   16篇
  1981年   17篇
  1980年   14篇
  1979年   35篇
  1978年   21篇
  1974年   13篇
  1969年   17篇
  1968年   14篇
  1967年   13篇
排序方式: 共有4155条查询结果,搜索用时 15 毫秒
991.
We examined the transmissibility of amyloidosis by the implantation of amyloid-containing tissue. If the transmissibility similar to prion diseases is applicable, using amyloid-containing tissue for transplantation in humans might be a risk factor. In this study, AA amyloidosis occurred in mice that underwent implantation of AA amyloid-containing grafts to the liver and subsequent inflammatory stimulation. AApoAII amyloidosis occurred after implantation of AApoAII amyloid-containing grafts to the liver or to the subcutaneous space without inflammatory stimulation. Both types of amyloidoses occurred in the recipient mice sooner than expected. Moreover, AA and AApoAII amyloid deposits were found at 12 weeks after implantation in mice given AApoAII amyloid-containing grafts and inflammatory stimulation. These results suggest that implanted amyloid deposits have an AEF effect and that implanted amyloid-containing tissue can promote and accelerate a different type of amyloidosis. In another experiment, mice received amyloid-containing or normal tissue grafts. The degree of amyloid deposition was compared after 6 days and 5 weeks of inflammatory stimulation and when the mice were killed. There was no obvious difference in the degree of amyloid deposition between each group, indicating that the lag-time is shortened by implantation of amyloid-containing tissue, resulting in severe amyloidosis in the short term.  相似文献   
992.
Acceleration of amyloid deposition by administration of amyloid fibrils and transmissibility of disease have been reported for several types of amyloidosis. Reactive amyloidosis (AA) occurs in a wide variety of domestic animal species and is characterized by amyloid deposition mainly in spleen, liver, and kidneys. Because the visceral organs of domestic animals have traditionally been used in Asian cuisines, it is important to examine whether dietary ingestion of the organs themselves (rather than purified amyloid fibrils) accelerates AA amyloid deposition. Herein, we show that murine AA amyloidosis develops rapidly after intraperitoneal or oral administration of purified amyloid fibrils or homogenates of amyloid-laden bovine liver. The amyloidosis development in mice was dependent on the concentration of amyloid fibrils or amyloidotic liver homogenates. We found that experimental murine AA amyloidosis was accelerated by dietary ingestion of both purified amyloid fibrils and tissue homogenates that contain amyloid fibrils. We also investigated livers of beef cattle and food chickens to examine whether they contain amyloid-enhancing factor activity. By microscopic examination of hematoxylin and eosin- and Congo red-stained sections, no amyloid deposition was detected in these livers, and no effective activity for experimental induction of AA amyloidosis in mice was detected in homogenates of these livers.  相似文献   
993.
994.
995.
STUDY DESIGN: Cross-sectional comparison. OBJECTIVE: The mortality rate is higher in individuals with spinal cord injury (SCI), and one major cause is cardiovascular disease (CVD). In the general population, the metabolic syndrome (MetS) is associated with an increased risk of CVD, and abdominal obesity is a major feature. Adipokines, secreted by adipose tissue, contribute to obesity-linked metabolic diseases. The aim of this study is to evaluate the prevalence of MetS, the components of this syndrome, especially body composition, and the relations between adipokines and body composition, in SCI individuals. SETTING: Kanagawa Rehabilitation Hospital, Kanagawa, Japan. METHODS: Forty-four male SCI individuals (57+/-13 years and 28 paraplegia) and age-matched able-bodied controls were studied. Body composition was assessed by dual-energy X-ray absorptiometry (DXA) and anthropometry (waist circumference). The visceral fat area (VFA) was measured by computed tomography (CT). Plasma adipokine levels, including that of leptin, adiponectin and plasminogen activator inhibitor-1 (PAI-1), were measured. RESULTS: Overall, 43% of SCI individuals met the criteria for MetS. Total and regional fat mass (FM), as well as VFA, were higher, whereas total and regional lean mass, except for arm, were lower than able-bodied controls. In the SCI, leptin and PAI-1 levels were positively associated and adiponectin levels were negatively associated with waist circumference, VFA and trunk FM. In multiple regression models, only leptin level was independently associated with waist circumference, VFA and trunk FM. CONCLUSION: SCI individuals were predisposed to excessive abdominal obesity, and higher leptin levels were strongly associated with higher prevalence of abdominal obesity in this population.  相似文献   
996.
OBJECTIVE: We investigated change in platelet activation using flow cytometry in patients before and after splenectomy with total gastrectomy for gastric cancer. METHODS: Six patients who underwent splenectomy for lymphadenectomy with total gastrectomy for gastric cancer were the subjects in this study. In the patients, platelet count and platelet activation were evaluated before the operation, 1 week after the operation, and 1 month after the operation. Expression of CD62P (P-selectin) was analysed as a marker of platelet activation using flow cytometry. RESULTS: Although platelet count significantly increased 1 week after the operation, the platelet count 1 month after the operation did not increase significantly. Expression of CD62P (P-selectin) significantly decreased at 1 week and 1 month after the operation, compared with the level before the operation. No postoperative complications occurred in any patient. CONCLUSION: In the present study, platelet activation did not progress after the operation. The results mean that the risk of thrombosis after splenectomy does not increase.  相似文献   
997.
BACKGROUND: Clinical studies conducted to elucidate the systemic response to cardiopulmonary bypass (CPB) did not differentiate possible effect of different types of cardiac surgical pathologies and operations on outcomes and have typically combined different procedures. We hypothesized that valve surgery induces more prominent systemic reaction compared to isolated on-pump CABG. METHODS: Twenty-seven patients undergoing primary on-pump CABG (Group 1, n = 14) or valve surgery with or without CABG (Group 2, n = 13) were prospectively enrolled. Heparin-bonded circuits were used in all patients. Cardiotomy suction was only used in Group 2. Clinical and laboratory markers were evaluated. RESULTS: Clinical measurements, including chest tube output, blood transfusion requirement, inotropic support requirement, and duration of ICU stay were not significantly different. Thrombin generation (PF-1.2) was significantly higher in Group 2 (p = 0.001). tPA was also significantly higher in Group 2 at 15 and 60 minutes on CPB (p < 0.01). Group 2 had significantly higher inflammatory response shown by elevation of IL6 (p = 0.005). Neuronal injury markers, S100beta and NSE, were significantly higher at the termination of CPB in Group 2 (p < 0.01). At no point of time course for any marker, Group 1 had significantly higher response compared to Group 2. CONCLUSIONS: Valve surgery induced more prominent systemic response than CABG. The possible explanations include the difference in baseline disease pathophysiology, and/or difference associated with the procedures such as open systems and use of cardiotomy suction. Future clinical studies assessing systemic response to CPB and therapies to blunt these need consider and account for these observed differences.  相似文献   
998.
PURPOSE: Chronic orofacial pain is often refractory to conventional pain therapies. We conducted an open-label study to determine whether adenosine 5'-triphosphate (ATP) could alleviate chronic intractable orofacial pain, and if so, which type of pain could respond to ATP. METHODS: In 8 and 16 patients with non-neuropathic and neuropathic intractable orofacial pain, respectively, ATP was intravenously infused at a rate of 100 microgxkg(-1)xmin(-1) over 120 min. The magnitudes of spontaneous pain and brush-evoked allodynia were graded with a visual analog scale (VAS). When a VAS score for spontaneous pain was decreased by 50% or more by ATP, the patient was classified as a responder. RESULTS: The patients could be clearly divided into 10 responders and 14 non-responders. Ten of the 16 patients (62.5%) with neuropathic pain, but none of the 8 patients with non-neuropathic pain, responded to ATP. In particular, all of 8 patients with neuropathic pain following pulpectomy, with or without subsequent tooth extraction, responded to ATP. In the 10 responders, VAS scores for spontaneous pain decreased slowly but progressively during the infusion period, and eventually, ATP reduced the VAS scores for spontaneous pain and allodynia by 82 +/- 15% and 74 +/- 9%, respectively. In these responders, the analgesic and anti-allodynic effects of ATP outlasted the infusion period for medians of 7 and 12 h, respectively. CONCLUSION: Intravenous ATP did not relieve non-neuropathic orofacial pain. However, it exerted slowly expressed but long-lasting analgesic and anti-allodynic effects in patients with neuropathic orofacial pain, especially in those suffering from neuropathic pain following pulpectomy and/or tooth extraction.  相似文献   
999.
OBJECTIVE: The insertion of absent or underexpressed genes into cancer cells to alter their malignant phenotype is an important potential application of available gene therapy technology. One of the more common viral vector systems that has been extensively studied for this purpose are the replication-deficient adenoviruses (Ad). Adenoviral infection of cells is mediated through a complex pathway, initiated following viral-cell attachment. Adenoviral-cell attachment occurs following interactions with a 46-kDa transmembrane protein with high affinity for both the Coxsackie and adenovirus, designated the CAR (Coxsackie and adenoviral receptor). Additional important cell-viral interactions that occur involve the alpha(v)-based integrins, specifically alpha(v)beta3 and alpha(v)beta5. The purpose of the present study was to determine the extent of expression and localization of the known Ad receptor proteins (CAR, alpha(v)beta3, and alpha(v)beta5) in normal and cancerous human bladders. MATERIAL AND METHODS: Frozen tissue samples of normal bladder and invasive transitional cell cancers of the bladder were evaluated. Tissue blocks containing muscle-invasive transitional cell carcinoma (TCC) were obtained following radical cystectomy, which were performed at our institution. Thirty-two invasive transitional cell bladder tumors were evaluated, each with a matched sample of histologically normal-appearing bladder used as a control. Four additional samples of normal bladder were obtained from patients with no evidence of disease of the bladder and served as further controls. Three additional cases of invasive bladder cancer with no matching normal tissue were also evaluated. Identification of the CAR receptor was performed using the anti-CAR mouse monoclonal antibody designated RmBC. The integrins alpha(v)beta3 and alpha(v)beta5 were identified using the mouse monoclonal antibodies designated LM609 and P1F6 respectively. All slides were evaluated by two of the authors (M.B., B.B.) without knowledge of the clinical and pathological data. RESULTS: Normal bladder: Normal bladder mucosa demonstrated a marked positivity for CAR in 29/35 (82.8%) cases. In contrast, normal transitional epithelial cells were uniformly negative when tested for the integrins alpha(v)beta3 and alpha(v)beta5. Subepithelial tissues, specifically the connective tissue components of the lamina propria and deep muscle wall of the bladder, were positive for alpha(v)beta3 and for alpha(v)beta5 in 61 and 75% of samples, respectively. Endothelial cells associated with the various layers throughout the bladder uniformly expressed both integrins and served as a consistent internal control for both antibodies. An almost identical staining pattern of the endothelium was observed using LM609 and P1F6 in all samples tested. Bladder transitional cell carcinoma: CAR immunoreactivity against TCC cells was uniformly decreased compared to normal transitional cells. Nine tumors exhibited a weak positivity for CAR while the remaining samples were negative. In some cases, the absence of CAR positivity was associated with histological evidence of carcinoma in situ. In 6 cases, it led to the identification of small regions of carcinoma in situ that were not noted on primary pathological evaluation. Peritumoral connective tissue expressed both integrins in the majority of cases, similar to the pattern described above for normal bladder. Transitional cell cancers demonstrated a similar pattern of expression of alpha(v)beta5, in which all tumor cells exhibited minimal or no staining. CONCLUSIONS: The success of all viral-mediated gene therapy strategies relies on the ability of the vector to efficiently deliver its genetic material to a target cell population. In the current study, we demonstrate that the bladder epithelial layer consistently expresses high levels of CAR. Deeper layers of the epithelium also express CAR, including the basal layer cells. A decrease in the expression of CAR appears as an early event in bladder carcinogenesis. We observed that both alpha(v)beta3 and alpha(v)beta5 are strongly expressed in muscle cells surrounding the neoplastic cells, as well as within the peritumoral connective tissue. In cases of invasive bladder cancer that have lost CAR expression, an adenoviral vector may still be utilized through the less efficient interactions with the integrins. Bladder tumor tissue may be less susceptible to an adenoviral-mediated gene therapy approach in which a significant percentage of tumor cells require transduction. Adenoviral uptake by tumor or peritumoral cells with subsequent gene transfer could be predicted by the level of CAR and alpha(v)-based integrin expression. This would enhance our ability to identify those patients whose tumors would be more susceptible to Ad-mediated gene delivery as part of an antitumor treatment.  相似文献   
1000.
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