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   23359篇
  免费   1617篇
  国内免费   266篇
耳鼻咽喉   367篇
儿科学   356篇
妇产科学   270篇
基础医学   3964篇
口腔科学   308篇
临床医学   2033篇
内科学   4515篇
皮肤病学   921篇
神经病学   1525篇
特种医学   1786篇
外科学   2745篇
综合类   84篇
一般理论   2篇
预防医学   929篇
眼科学   657篇
药学   2360篇
中国医学   337篇
肿瘤学   2083篇
  2024年   15篇
  2023年   175篇
  2022年   612篇
  2021年   866篇
  2020年   455篇
  2019年   626篇
  2018年   733篇
  2017年   639篇
  2016年   969篇
  2015年   1404篇
  2014年   1580篇
  2013年   1742篇
  2012年   2395篇
  2011年   2181篇
  2010年   1470篇
  2009年   1153篇
  2008年   1477篇
  2007年   1354篇
  2006年   1180篇
  2005年   1091篇
  2004年   818篇
  2003年   685篇
  2002年   557篇
  2001年   152篇
  2000年   147篇
  1999年   100篇
  1998年   94篇
  1997年   81篇
  1996年   66篇
  1995年   34篇
  1994年   35篇
  1993年   26篇
  1992年   40篇
  1991年   42篇
  1990年   24篇
  1989年   26篇
  1988年   20篇
  1987年   16篇
  1986年   22篇
  1985年   25篇
  1984年   16篇
  1983年   11篇
  1982年   6篇
  1981年   8篇
  1980年   5篇
  1979年   14篇
  1978年   8篇
  1976年   6篇
  1973年   5篇
  1971年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Koh YY  Kang EK  Kang H  Yoo Y  Park Y  Kim CK 《Chest》2003,124(3):819-825
BACKGROUND: The mechanisms responsible for bronchial hyperresponsiveness (BHR) in symptomatic asthma include genetic predisposition and airway inflammation, but the causes of BHR in adolescents with asthma remission are poorly understood. It has been shown that BHR in adolescents with asthma remission was not reduced by prolonged treatment with inhaled corticosteroids, in contrast to the BHR of symptomatic asthma. OBJECTIVE: The aim of this study was to investigate whether family history of BHR may contribute to the persistence of BHR in asthma remission during adolescence. METHODS: One hundred twenty-six adolescents with long-term asthma remission (neither symptoms nor any medication used during the previous 2 years) and their parents underwent a methacholine inhalation test. The provocative concentration of methacholine causing a 20% fall in FEV(1) (PC(20)) and the bronchial responsiveness (BR) index were calculated for each individual. RESULTS: Sixty-nine adolescents (54.8%) were found to have persisting BHR (PC(20) < 18 mg/mL). The frequency of BHR and the BR index were significantly higher in parents (n = 138) of the BHR-persisting group (28.3% and 1.150 +/- 0.103, respectively [mean +/- 1 SD]) than in parents (n = 114) of BHR-nonpersisting group (16.7% [p = 0.030] and 1.124 +/- 0.088 [p = 0.029], respectively). Furthermore, adolescents (n = 56) with at least one BHR-positive parent were found to have a higher frequency of BHR (66.1% vs 45.7%, p = 0.023) and a higher BR index (1.244 +/- 0.090 vs 1.204 +/- 0.082, p = 0.011) than adolescents (n = 70) with non-BHR parents. CONCLUSION: Our results suggest that adolescents in asthma remission are more likely to have BHR when there is a family history of BHR. Further studies are needed to examine the possible involvement of genetic factors in the BHR of adolescents in asthma remission.  相似文献   
992.
Portal vein thrombosis is a rare complication accompanied with acute pancreatitis or cholangitis/cholecystitis. The main pathogenesis of portal vein thrombosis in pancreatitis or cholangitis/cholecystitis are suggested to be venous compression by pseudocyst and an imbalance between the blood coagulation and fibrinolysis. In this case report, we experienced a 63 year old male who developed portal vein thrombosis later in the course of the treatment of acute gallstone pancreatitis with cholangitis/cholecystitis without any symptom or sign. The diagnosis of portal vein thrombosis was given on follow up CT scan and serum protein S activity was decreased to 27% in laboratory study. Immediate anticoagulation therapy with heparin and thrombolytic therapy with urokinase and balloon dilatation were performed. Despite the aggressive treatment, complete reperfusion could not be obtained. With oral warfarin anticoagulation, the patient showed no disease progression and was discharged. We report a case of portal vein thrombosis as a complication of acute pancreatitis and cholangitis/cholecystitis with a review of literatures.  相似文献   
993.
BACKGROUND: The nonlifting sign is widely used for evaluating the invasion depth of colorectal tumors, and it is commonly accepted that EMR is contraindicated for colorectal tumors with a nonlifting sign because of the probability of massive submucosal invasion. OBJECTIVE: To identify the clinicopathologic factors that affect the nonlifting sign in submucosal invasive colorectal carcinoma (SICC). DESIGN: Details regarding a history of biopsy, postbiopsy days, tumor location, tumor configuration, tumor size, depth of submucosal invasion, histologic type, adenomatous remnants, and angiolymphatic invasion were studied in relation to the nonlifting sign. SETTING: National Cancer Center, Korea. PATIENTS: The study involved 76 patients with SICC treated by endoscopic or surgical resection, in whom the tumor was examined for the nonlifting sign from 2001 to 2006. RESULTS: The nonlifting sign was observed in 15 cases (19.7%). A deep submucosal invasion, a history of biopsy, and the absence of adenomatous remnants were identified as factors affecting the nonlifting sign in univariate and multivariate analyses (P < .05). An increase in the number of postbiopsy days was associated with the nonlifting sign in endoscopically resectable SICC, and all 11 sm1 cancer cases with fewer than 21 postbiopsy days showed lifting. CONCLUSIONS: A history of biopsy and the absence of adenomatous remnants, in addition to deep submucosal invasion, were found to influence the nonlifting sign in SICC. It may be best that mechanical stimulation such as forceps biopsies are minimized before EMR, and EMR should be tried as soon as possible if biopsy was performed.  相似文献   
994.

Background

Sodium meta-arsenite (NaAsO2, KML001) is a potential oral anticancer agent acting on telomerase and telomere length. This prospective study evaluated its safety, tolerability, and effectiveness as salvage chemotherapy in patients with advanced biliary tract cancer (BTC) resistant to gemcitabine-based chemotherapy.

Methods

Forty-four patients (21 women and 23 men) with advanced BTC and failure history of gemcitabine-based chemotherapy, performance status (PS) 0–2, normal cardiac, hepatic, and renal function were enrolled. Daily dose of KML001 (7.5?mg. p.o.) was administered to eligible subjects for 24 weeks divided into six treatment cycles. Response was evaluated bimonthly using CT.

Results

After an average of 1.5 months of treatment (range: 0.5–10.0), 3 patients (6.8%) obtained progression-free status, 23 patients (52.3%) had disease progression, and 18 patients (40.9%) dropped out before evaluation. One patient (2.3%) completed six treatment cycles without progression. During the treatment, morphine dosage kept the same or decreased in 20 patients (47.6%). Nine patients (20.5%) experienced grade-3 adverse events (AEs), while no patient experienced grade-4 AEs. The most common AEs were liver enzyme elevation (11/44, 25%) and anemia (10/44, 22.7%). KML001 was discontinued in six patients (13.6%) due to AEs, including liver toxicity (n?=?3), QTc prolongation (n?=?2), and abdominal pain (n?=?1).

Conclusions

KML001 did not have enough anticancer effect on patients with advanced BTC resistant to gemcitabine. However, KML001 was safe and well-tolerable in terms of AEs and pain control when used as salvage therapy. Further studies are needed to establish arsenic agents as a reliable treatment option in patients with BTC.  相似文献   
995.
BACKGROUND/AIMS: Hedgehog protein is an essential molecule for gastrointestinal tract development, and disruption of hedgehog signaling pathway is linked to some gastrointestinal tumorigenesis. Here, we performed hedgehog immunostaining in periampullary cancer to evaluate the differences according to the location type of cancer and the differentiation of adenocarcinoma. METHODS: We retrieved surgical specimens from 43 periampullary cancer patients (15 ampulla of Vater cancer, 12 distal common bile duct cancer, 13 pancreatic head cancer, and 3 combined ampulla of Vater/bile duct cancer). Immunohistochemical stain was performed in both normal and cancerous tissue portions of each case using Sonic hedgehog (H-160) rabbit polyclonal antibody. Immunohistochemical stain results were grouped into three groups according to the percentage of positive cytoplasmic stain in tumor volume (unstained: <5%, weakly stained: 5-50%, and strongly stained: >50%). RESULTS: All of the normal tissue revealed negative immunohistochemical stain while cancerous tissue revealed positivity in 95.3% (41/43 cases). Strongly stained cases were more frequently seen in ampulla of Vater cancers (13/15) and in combined ampulla of Vater/bile duct cancers (3/3) than in distal common bile duct cancers (4/12) and in pancreatic head cancers (3/13) (p=0.002). In addition, strongly stained cases were more frequently seen in well-differentiated adenocarcinoma than the others (p<0.001). CONCLUSIONS: Most of the periampullary cancers show hedgehog protein expression. In addition, hedgehog protein immunostainings shows stronger expression in ampulla of Vater cancers and in well-differentiated adenocarcinoma.  相似文献   
996.
BACKGROUND/AIMS: Although previous reports suggested that pepsinogen (PG) I/II ratio was the index of gastric atrophy, PG I/II ratio was also related to other factors such as Helicobacter pylori (H. pylori) infection, various gastrointestinal diseases, and aging. The aim of this study was to evaluate the relationship between serum PG I/II ratio and age or upper gastro-intestinal diseases according to H. pylori infection status. METHODS: A total of 529 individuals (307 male; mean age, 57.2 years) were divided into 4 groups (94 gastric ulcers, 35 duodenal ulcers, 105 reflux esophagitis, and 295 atrophic gastritis) according to endoscopic diagnosis. H. pylori infection was determined by H. pylori IgG antibody (ELISA) and PG was measured by latex immunoassay. RESULTS: H. pylori infected patients showed markedly increased serum PG II levels (24.0+/-14.7 ng/mL vs. 13.8+/-16.6 ng/mL, p0.001) and low PG I/II ratio (3.9+/-2.0 vs. 6.0+/-2.5, p0.001) than non-infected subjects. In H. pylori infected patients, mean PG I/II ratios in the gastric ulcer and atrophic gastritis group were significantly lower than those of the duodenal ulcer and reflux esophagitis group (p0.001, ANOVA, Turkey's multiples comparison test). The mean ratio of open type atrophic gastritis was lower than that of close type atrophic gastritis (3.0+/-1.4 vs. 3.8+/-1.7, p0.005). PG I/II ratio gradually decreased with age in H. pylori-infected patients with atrophic gastritis (R(2)=0.9, p=0.005, linear regression analysis). CONCLUSION: Serum PG I/II ratio reflects H. pylori infection and gastric atrophy. In the presence of H. pylori infection, gastric atrophy progresses with age.  相似文献   
997.
Acrylamide (AA) and N-acetyl-S-(2-carbamoylethyl)-cysteine (AAMA) are important urinary biomarkers of acrylamide exposure in human biomonitoring, because AA is classified as a probable carcinogen in humans.  相似文献   
998.
999.
A 70-year-old woman presented with headaches and recurrent stroke symptoms. During five years, the patient has been treated for cerebral infarction associated with severe atherosclerotic stenosis of the internal carotid artery. Three-year follow-up magnetic resonance angiography showed a tiny de novo aneurysm arising from the distal part of atherosclerotic internal carotid artery. And 5-year follow-up three-dimensional CT angiogram demonstrated a definite aneurysm enlargement as large as requiring treatment. During dissection of aneurysm, the oculomotor nerve was found to be penetrated with the growing de novo aneurysm. The authors report a case of a de novo aneurysm, which resulted from atherosclerotic stenosis of the internal carotid artery at the supraclinoid portion, that was found to be penetrating the oculomotor nerve with no ocular palsy.  相似文献   
1000.
The current study examines the perceived differences of stress and stress coping strategies between smoking and nonsmoking South Korean casino workers. Casino employees (N?=?621) were grouped into two groups (i.e., smokers and nonsmokers). Using logistic regression analysis with cigarette smoking as the dependent variable, investigators observed that nonsmokers were more likely to report stress related to work or job issues and identify their leisure activity as a form of personal development compared with smokers. Casino employees have a higher prevalence of tobacco smoking than the general population and smoking behaviors tend to cluster with alcohol use and gambling. These findings suggest that smoking cession programs might benefit from taking into account how to provide personal development as a type of leisure.  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