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   50221篇
  免费   2346篇
  国内免费   242篇
耳鼻咽喉   773篇
儿科学   884篇
妇产科学   802篇
基础医学   6589篇
口腔科学   1437篇
临床医学   3441篇
内科学   12085篇
皮肤病学   667篇
神经病学   3948篇
特种医学   1709篇
外科学   8821篇
综合类   234篇
一般理论   2篇
预防医学   1732篇
眼科学   808篇
药学   3903篇
中国医学   119篇
肿瘤学   4855篇
  2023年   276篇
  2022年   561篇
  2021年   940篇
  2020年   472篇
  2019年   649篇
  2018年   819篇
  2017年   612篇
  2016年   790篇
  2015年   794篇
  2014年   1071篇
  2013年   1390篇
  2012年   2301篇
  2011年   2417篇
  2010年   1436篇
  2009年   1195篇
  2008年   2334篇
  2007年   2518篇
  2006年   2433篇
  2005年   2451篇
  2004年   2358篇
  2003年   2345篇
  2002年   2319篇
  2001年   1711篇
  2000年   1847篇
  1999年   1600篇
  1998年   639篇
  1997年   517篇
  1996年   462篇
  1995年   401篇
  1994年   362篇
  1993年   331篇
  1992年   1154篇
  1991年   980篇
  1990年   939篇
  1989年   984篇
  1988年   882篇
  1987年   873篇
  1986年   802篇
  1985年   786篇
  1984年   551篇
  1983年   440篇
  1982年   237篇
  1979年   488篇
  1978年   287篇
  1977年   263篇
  1975年   212篇
  1974年   228篇
  1971年   234篇
  1969年   234篇
  1968年   216篇
排序方式: 共有10000条查询结果,搜索用时 796 毫秒
51.
OBJECTIVE: To assess the functional results, health-related quality of life (QOL) outcomes, and complications in patients with an ileal neobladder in comparison to those with cutaneous diversion (ileal conduit and cutaneostomy). METHODS: Between September 1992 and February 2003, we consecutively performed an ileal neobladder (the Studer method) in 30 patients and cutaneous diversion in 38 patients. In August 2004, questionnaires were mailed to 54 patients. The questionnaire included the validated health-related quality of life (QOL) questionnaire, SF-36 General Health Survey, and a urinary incontinence questionnaire. We also evaluated the functional results in patients with an ileal neobladder and the postoperative complications in patients with both urinary diversions. RESULTS: The data from 41 patients (21 ileal neobladder procedures and 20 cutaneous diversions) were available for the analysis. No differences in the overall QOL were observed between the two groups. Complete daytime and night-time urinary continence was achieved in the 21 patients (100%) and 13 patients (61.9%), respectively. The mean value of the maximum flow rate was 15 +/- 12 mL/min in the 21 neobladder patients. There were 19 early complications in 18 patients (60.0%) and seven late complications in six patients (20.0%) with an ileal neobladder. However, there were 15 early complications in 14 patients (36.8%) and eight late complications in six patients (15.8%) with cutaneous diversions. CONCLUSION: The findings regarding the health-related QOL and the frequency of complications in the neobladder group and those in the cutaneous diversion group were similar. However, the functional results and the status of urinary continence in the neobladder patients were satisfactory.  相似文献   
52.
The presence of blood in the ejaculate is called hematospermia or hemospermia. While often perceived as a symptom of little significance, hematospermia can cause great concern to men who experience it. We report an unusual case of hematospermia associated with pelvic arteriovenous malformation (AVM). A 60-year-old man who visited our hospital complaining of hematospermia and pollakisuria was found to have AVM and aneurysmal changes in the left side of the pelvis using computed tomography (CT). The patient was treated with steel coil embolization of the left inferior gluteal artery, and after the procedure the hematospermia and pollakisuria remained absent without flare-ups.  相似文献   
53.
BACKGROUND: Oral submucous fibrosis (OSF) is a chewing habit-related pre-cancerous condition of the oral mucosa affecting predominantly south Asians. It is histopathologically characterized by epithelial atrophy and fibrosis of the subepithelial connective tissue. Fibrosis extends all the way into the muscle layer, leading to difficulty in mouth opening. However, the dynamics of extracellular matrix (ECM) remodeling with OSF progression is largely unknown. METHODS: Forty biopsy specimens of OSF and 10 of normal buccal mucosa were examined for expression/deposition modes of eight ECM molecules by histochemistry, immunohistochemistry, and in situ hybridization. RESULTS: In the early stage of OSF, tenascin, perlecan, fibronectin, collagen type III were characteristically enhanced in the lamina propria and the submucosal layer. In the intermediate stage, the ECM molecules mentioned above and elastin were extensively and irregularly deposited around muscle fibers. In the advanced stage, such ECM depositions decreased and were entirely replaced with collagen type I only. Their gene expression levels varied with progression of fibrosis, but the mRNA signals were confirmed in fibroblasts in the submucosal fibrotic areas. CONCLUSIONS: The results indicate that the ECM remodeling steps in OSF are similar to each phase of usual granulation tissue formation. Restricted mouth opening may be a result of loss of variety of ECM molecules including elastin into the homogeneity of collagen type I replacing muscle fibers.  相似文献   
54.
The immunohistochemical localization of manganese (Mn)-superoxide dismutase (Mn-SOD) was studied in the rat basal forebrain using polyclonal antibodies to Mn-SOD. Neurons of the basal forebrain exhibit a high density of Mn-SOD immunoreactivity. Double immunostaining with a monoclonal antibody to choline acetyltransferase demonstrated that both cholinergic and non-cholinergic neurons in the basal forebrain are intensely immunoreactive for Mn-SOD.  相似文献   
55.
Y Yoshiike  S Suzuki  Y Watanuki    T Okubo 《Thorax》1995,50(2):139-142
BACKGROUND--The effects of beta 2 adrenergic agonists on chemoreceptors remain controversial. This study was designed to examine whether fenoterol, a beta 2 adrenergic agonist, increases the ventilatory responses to hypercapnia (HCVR) and hypoxia (HVR) in normal subjects. METHODS--HCVR was tested with a rebreathing method and HVR was examined with a progressive isocapnic hypoxic method in 11 normal subjects. Both HCVR and HVR were assessed by the slope of occlusion pressure (P0.1) or ventilation (VE) plotted against end tidal carbon dioxide pressure and arterial oxygen saturation, respectively. Respiratory muscle strength, spirometric values and lung volume were measured. After a single oral administration of 5 mg fenoterol or placebo HCVR and HVR were evaluated. RESULTS--Fenoterol treatment did not change the specific airway conductance or forced expiratory volume in one second. Respiratory muscle strength did not change. Fenoterol increased the slope of the HCVR of both P0.1 (from 0.251 (0.116) to 0.386 (0.206) kPa/kPa, average increase 71%) and VE (from 10.7 (3.4) to 15.1 (4.2) l/min/kPa, average increase 52%), and shifted the response curves to higher values. For the HVR fenoterol increased the slopes of both P0.1 and VE (from -4.06 (2.00) x 10(-3) to -7.99 (4.29) x 10(-3) kPa/%, an average increase of 83%, and from -0.221 (0.070) to -0.313 (0.112) l/min/%, a 44.5% increase, respectively), and shifted the response curves to higher values. CONCLUSION--Acute administration of fenoterol increases the ventilatory responses to both hypercapnia and hypoxia in normal subjects.  相似文献   
56.
The centrifugal pump (bio-pump) as a temporary shunt during the operation of the descending thoracic aortic aneurysms was used as effective means of providing adequate circulation to the lower body. But in the acute excessive bleeding, estimates of the flow to the abdominal viscera as well as spinal cord are variable. We employed bio-pump with an interposed soft reservoir under low dose systemic heparinization in 2 cases of the descending thoracic aortic aneurysms. Both cases had been maintained adequate flow and perfusion pressure in the time of acute excessive hemorrhage, and there were no evidence of the organ failures due to microembolism. Furthermore, postoperative hemorrhage by using low dose heparin seemed to be unrisky. Compared with the previous method, bio-pump with an interposed soft reservoir provides adequate circulation to the lower body even if acute excessive bleeding occurred.  相似文献   
57.
58.
59.
Arterial blood ketone body ratio (AKBR; acetoacetate/beta-hydroxybutyrate) is known as a parameter to indicate the function of the liver cells. We evaluated the effects of induced hypotension with prostaglandin E1 (PGE1) or trimetaphan (TMP) on AKBR in patients without liver disease undergoing mastectomy. Almost no change was observed in AKBR before, during and after hypotension with PGE1, but slight diminution was observed during hypotension with TMP. No hepatic dysfunction, however, developed in these patients postoperatively. These findings suggest that usual hypotension with TMP may provoke no postoperative hepatic dysfunction in patients without liver disease. For the patient who required either hypotension of long duration or hypotension with other factors affecting function of liver (surgical procedures, drugs and others), we prefer PGE1 to TMP as a hypotensive drug. We should also adopt PGE1 when cardiovascular control with hypotensive drug is necessary in patients with liver disease.  相似文献   
60.
Hepatocyte regeneration has been widely investigated, with the mitotic index and the incorporation of [3H]thymidine being used as regeneration markers. We focused on the induction of DNA replication enzymes, particularly DNA polymerases (pol) α, δ, and ε. Using rat models, we have shown that the activity of pol α in crude liver extract well represents the regenerating capacity of hepatocytes. Using pol α as an indicator, we analyzed liver regeneration in rat models under various conditions: obstructive jaundice, external or internal biliary drainage, and the obstruction of portal vein branches. It has been revealed that the ligation of the common bile duct alone induces a certain amount of hepatocyte proliferation. It was striking that external biliary drainage suppressed regeneration capacity in cholestatic rat liver after partial hepatectomy. The strong regeneration in nonligated lobes induced by portal branch ligation was similar to the liver regeneration seen after partial hepatectomy with respect to the induction of DNA polymerases. Taken together, the aspects of DNA replication, particularly the induction of DNA polymerases, may contribute to shedding new light on the regeneration of human liver. This work was supported in part by a Grant-in-Aid for General Scientific Research and for Cancer Research from the Ministry of Education, Science and Culture, Japan, and by grants from the Uehara Memorial Foundation  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