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   15880篇
  免费   975篇
  国内免费   370篇
耳鼻咽喉   221篇
儿科学   177篇
妇产科学   156篇
基础医学   2530篇
口腔科学   293篇
临床医学   1565篇
内科学   3040篇
皮肤病学   519篇
神经病学   1072篇
特种医学   1570篇
外科学   1809篇
综合类   71篇
一般理论   3篇
预防医学   523篇
眼科学   249篇
药学   1935篇
  1篇
中国医学   268篇
肿瘤学   1223篇
  2024年   8篇
  2023年   128篇
  2022年   471篇
  2021年   661篇
  2020年   313篇
  2019年   470篇
  2018年   562篇
  2017年   467篇
  2016年   651篇
  2015年   871篇
  2014年   1022篇
  2013年   1120篇
  2012年   1473篇
  2011年   1503篇
  2010年   914篇
  2009年   711篇
  2008年   899篇
  2007年   947篇
  2006年   706篇
  2005年   660篇
  2004年   562篇
  2003年   404篇
  2002年   329篇
  2001年   185篇
  2000年   147篇
  1999年   96篇
  1998年   123篇
  1997年   105篇
  1996年   95篇
  1995年   72篇
  1994年   54篇
  1993年   58篇
  1992年   30篇
  1991年   30篇
  1990年   25篇
  1989年   60篇
  1988年   37篇
  1987年   34篇
  1986年   33篇
  1985年   29篇
  1984年   19篇
  1983年   15篇
  1982年   27篇
  1981年   14篇
  1980年   14篇
  1979年   6篇
  1978年   4篇
  1977年   17篇
  1976年   30篇
  1975年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Solanum nigrum L., commonly known as black nightshade, is used worldwide for the treatment of skin and mucosal ulcers, liver cirrhosis and edema. We aimed to determine the anti-inflammatory active fraction of S. nigrum by serial extractions. S. nigrum was first extracted with methanol, then fractionated with chloroform and water. The effects of S. nigrum fractions, diosgenin and α-solanine on LPS/interferon-gamma-induced nitric oxide (NO) and inducible NO synthase (iNOS), or LPS-induced tumor necrosis factor-α (TNF-α) and interleukin (IL)-6, in mouse peritoneal macrophages were determined. Western blotting analysis was used to detect LPS-induced phosphorylation of p38, JNK and ERK1/2. The chloroform fraction of S. nigrum was cytotoxic in a time and concentration dependent manner; however, the methanol and water fractions were not. The chloroform fraction reduced NO through inhibition of iNOS synthesis and inhibited TNF-α and IL-6 at the level of protein secretion; the methanol and water fractions showed a weak or no effect. The chloroform fraction also suppressed p38, JNK and ERK1/2. Diosgenin and α-solanine were cytotoxic at a high concentration. In particular, diosgenin was able to inhibit TNF-α and IL-6, but both compounds did not affect LPS-induced iNOS expression. These results indicate that the anti-inflammatory compounds of S. nigrum exist preferentially in the nonpolar fraction, ruling out the possibility that diosgenin and α-solanine are the likely candidates. The inhibition of iNOS, TNF-α and IL-6 by the chloroform fraction may be partly due to the suppression of p38, JNK and ERK1/2. Further study is required to identify the active compounds of S. nigrum.  相似文献   
92.
Bioassay-guided fractionation of an 80% MeOH extract of leaves and twigs of Juglan sinensis has resulted in the isolation of four new triterpenes (1-4) and 17 known triterpenes (5-21). The new compounds were determined to be 1-oxo-3β,23-dihydroxyolean-12-en-28-oic acid 28-O-β-D-glucopyranoside (1), 1-oxo-3β-hydroxyolean-18-ene (2), 3β,23-dihydroxyurs-12-en-28-oic acid 28-O-β-D-glucopyranoside (3), and 3β,22α-dihydroxyurs-12-en-28-oic acid 28-O-β-D-glucopyranoside (4) by spectroscopic analysis. Compounds 2, 13, 15, and 21 showed antiproliferative activities (14.2, 14.8, 15.6, and 11.0% at 100 μM, respectively) in HSC-T6 cells. Flow cytometry assays revealed that these compounds inhibited HSC-T6 proliferation by inducing apoptosis.  相似文献   
93.
To develop a hyaluronic microsphere with the improved oral bioavailability of poorly water-soluble cyclosporin A (CsA), the microspheres were prepared with varying ratios of sodium hyaluronate (HA)/sodium lauryl sulfate (SLS)/CsA using a spray-drying technique. The effects of HA and SLS on the dissolution and solubility of CsA in microspheres were investigated. The CsA-microsphere prepared with HA/SLS/CsA at the ratio of 4/2/1 gave the highest solubility and dissolution rate of CsA among those formulae tested. As solubility and dissolution rate of CsA were increased about 17- and 2-fold compared to CsA powder, respectively, this CsA-microsphere was selected as an optimal formula for oral delivery in rats. The CsA-microsphere and Sandimmun neoral sol gave significantly higher blood levels compared with CsA powder alone. Moreover, the AUC, T(max) and C(max) values of CsA in CsA-microsphere were not significantly different from those in Sandimmun neoral sol in rats, indicating that CsA-microsphere was bioequivalent to the commercial product in rats. Our results demonstrated that the CsA-microsphere prepared with HA and SLS, with improved bioavailability of CsA, might have been useful to deliver a poorly water-soluble CsA.  相似文献   
94.
Objective:The effectiveness of adjuvant treatments for resected gallbladder carcinoma (GBC) has remained unclear due to lack of randomized controlled trials; thus, the aim of present study was to evaluate the role of adjuvant treatments, including chemoradiotherapy (CRT) and/or chemotherapy (CTx), in patients with resected GBC.Methods:A total of 733 GBC patients who received curative-intent surgical resection were identified in a multi-institutional database. Of 733 patients, 372 (50.8%) did not receive adjuvant treatment, whereas 215 (29.3%) and 146 (19.9%) received adjuvant CTx and CRT, respectively. The locoregional recurrence-free survival (LRFS), recurrence-free survival (RFS), and overall survival (OS) of the adjuvant treatment groups were compared according to tumor stage (stage II vs. stage III–IV).Results:In stage II disease (n = 381), the 5-year LRFS, RFS, and OS were not significantly different among the no-adjuvant therapy, CTx, and CRT groups, and positive resection margin, presence of perineural invasion, and Nx classification were consistently associated with worse LRFS, RFS, and OS in the multivariate analysis (P < 0.05). For stage III–IV (n = 352), the CRT group had significantly higher 5-year LRFS, RFS, and OS than the no-adjuvant therapy and CTx groups (67.8%, 45.2%, and 56.9%; 37.9%, 28.8%, and 35.4%; and 45.0%, 30.0%, and 45.7%, respectively) (P < 0.05).Conclusions:CRT has value as adjuvant treatment for resected GBC with stage III–IV disease. Further study is needed for stage II disease with high-risk features.  相似文献   
95.
Background/AimsWe examined the efficacy and safety of tegoprazan as a part of first-line triple therapy for Helicobacter pylori eradication.MethodsA randomized, double-blind, controlled, multicenter study was performed to evaluate whether tegoprazan (50 mg)-based triple therapy (TPZ) was noninferior to lansoprazole (30 mg)-based triple therapy (LPZ) (with amoxicillin 1 g and clarithromycin 500 mg; all administered twice daily for 7 days) for treating H. pylori. The primary endpoint was the H. pylori eradication rate. Subgroup analyses were performed according to the cytochrome P450 (CYP) 2C19 genotype, the minimum inhibitory concentration (MIC) of amoxicillin and clarithromycin, and underlying gastric diseases.ResultsIn total, 350 H. pylori-positive patients were randomly allocated to the TPZ or LPZ group. The H. pylori eradication rates in the TPZ and LPZ groups were 62.86% (110/175) and 60.57% (106/175) in an intention-to-treat analysis and 69.33% (104/150) and 67.33% (101/150) in a per-protocol analysis (non-inferiority test, p=0.009 and p=0.013), respectively. Subgroup analyses according to MICs or CYP2C19 did not show remarkable differences in eradication rate. Both first-line triple therapies were well-tolerated with no notable differences.ConclusionsTPZ is as effective as proton pump inhibitor-based triple therapy and is as safe as first-line H. pylori eradication therapy but does not overcome the clarithromycin resistance of H. pylori in Korea (ClinicalTrials.gov identifier NCT03317223).  相似文献   
96.
Iodinated contrast media (ICM) have become one of the major causes of drug hypersensitivity reactions (HSRs) related to increasing numbers of ICM-based radiological imaging procedures. Strategies for diagnosing and preventing ICM-induced HSRs have not been uniformly standardized yet. However, advances have been made based on the results of recent research. A previous history of hypersensitivity to ICM is the most significant risk factor for developing HSR by ICM. Avoidance of culprit agents and premedication is the main strategy to prevent recurrences of HSRs in high-risk patients. In addition, we strongly recommend identifying sensitized ICM using skin tests to determine immunoglobulin E-mediated or delayed-type allergy and to guide the choice of an alternative contrast agent. ICM provocation test procedures have been established and are helpful in selected cases. In this paper, we review how to evaluate patients who have experienced immediate or delayed HSRs caused by ICM to minimize the risk of recurrence and discuss unmet needs that require further research.  相似文献   
97.
98.
This study investigated the association between micronutrient intake and breast cancer risk in South Korean adult women. This association was stratified according to body mass index (BMI) categories. Data from the Korean Genome and Epidemiology Study (KoGES) and the Health Examinee Study were analyzed. Altogether, 63,337 individuals (aged ≥40 years) completed the baseline and first follow-up surveys; 40,432 women without a history of cancer at baseline were included in this study. The association between micronutrient intake and breast cancer was determined by estimating the hazard ratio (HR) and 95% confidence interval (CI) using the Cox proportional hazard regression model. A stratified analysis by BMI (<25 kg/m2 and ≥25 kg/m2) was performed. The an analysis of 15 micronutrients and breast cancer risk revealed that none of the micronutrients were associated with breast cancer risk after adjusting for covariates. In obese women, the risk of breast cancer was significantly reduced in the group that consumed vitamin C more than the recommended level (HR = 0.54, 95% CI: 0.31–0.93) and vitamin B6 levels above the recommended level (HR = 0.48, 95% CI: 0.25–0.89). In obese women, exceeding the recommended daily intake levels of vitamin C and vitamin B6 was associated with a lower risk of breast cancer. However, other micronutrients were not associated with breast cancer risk in these women.  相似文献   
99.
Colorectal cancer is a common cancer; generally, adults aged ≥ 50 years are screened using stool occult blood tests and colonoscopy. However, colorectal adenoma and cancer have been found in patients under the aged of 50, and studies on characteristics and risk factors in young patients are lacking. We evaluated the prevalence and risk factors of colorectal adenoma and cancer in young adults aged under 50 years.We retrospectively analyzed 570 individuals aged under 50 years who underwent colonoscopy at the Haeundae Paik Hospital, Korea, from January to June 2018. Logistic regression model was used to identify the risk factors for colorectal adenoma and colorectal cancer.The prevalence of colorectal adenoma in group of 19–29 years was 3.2% (1 of 31), 30–39 years was 13.8% (30 of 217) and in the group of 40–49 years was 21.1% (68 of 322) (P = .009). In multivariable analysis, age over 45 years (adjusted odds ratio [OR], 1.941; 95% confidence interval [CI], 1.187–3.172; P = .008) and male sex (adjusted OR, 1.711; 95% CI, 1.044–2.806; P = .033) were independent risk factors for colorectal neoplasia including cancer.The prevalence of colorectal adenoma increases as the age increased in young adults under 50 years of age, especially after the age of 45 years, the risk of colorectal neoplasia increases; hence, early screening should be considered before the age of 50 years.  相似文献   
100.
Bronchiolitis generally refers to inflammation and/or fibrosis of the non-cartilaginous small airways located approximately from the 8th airway generation down to the terminal and respiratory bronchioles. In contrast to young children, the frequency of small airway infection in adult bronchiolitis appears less frequent and a number of other pathophysiological conditions have been implicated in adult bronchiolitis. However, little information is available on the exact medical burden of bronchiolitis such as its prevalence and comorbidities in the adult population. The aim of this study is to elucidate the prevalence and comorbidities of bronchiolitis. We used the Korea National Health Insurance Service-National Sample Cohort, which provides data for 1,000,000 individuals out of the entire population by 2% stratified random sampling according to age, sex, residential area, and level of household income. We defined the cause of bronchiolitis other than acute infection as a patient with diagnostic code J448 or J684 and over 20 years of age who visited a clinic or hospital in South Korea. Then, 1:1 propensity score matching was performed to define a non-bronchiolitis (control) group to compare the comorbidities and mortality in the 2 groups. The overall prevalence of bronchiolitis was 688 cases/1,000,000 population during the study period (95% confidence interval, 625–751). The most common comorbid clinical condition in adults with bronchiolitis was rhinitis (52.3%), followed by bronchial asthma (52.23%), hypertension (43.69%), gastroesophageal reflux disease (30.56%), sinusitis (28.72%), diabetes (22.77%), and osteoporosis (17.85%). Other common bronchiolitis-associated comorbidities were cerebrovascular disease (16.86%), angina (14.37%), peripheral vascular disease (13.42%), congestive heart failure (11.9%), and malignancy in any organ (10.6%). Healthcare costs for bronchiolitis increased steeply during the same period. Malignancy in any organ was the leading cause of mortality in the patient group, followed by bronchiolitis itself. Further larger prospective multiethnic cohort studies should be carried out in the near future.  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