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   721篇
  免费   35篇
  国内免费   5篇
耳鼻咽喉   3篇
儿科学   28篇
妇产科学   23篇
基础医学   94篇
口腔科学   51篇
临床医学   63篇
内科学   126篇
皮肤病学   18篇
神经病学   56篇
特种医学   26篇
外科学   83篇
综合类   20篇
预防医学   49篇
眼科学   11篇
药学   57篇
中国医学   9篇
肿瘤学   44篇
  2024年   3篇
  2023年   6篇
  2022年   23篇
  2021年   34篇
  2020年   28篇
  2019年   25篇
  2018年   32篇
  2017年   33篇
  2016年   27篇
  2015年   26篇
  2014年   33篇
  2013年   56篇
  2012年   57篇
  2011年   53篇
  2010年   42篇
  2009年   38篇
  2008年   40篇
  2007年   43篇
  2006年   40篇
  2005年   30篇
  2004年   22篇
  2003年   15篇
  2002年   6篇
  2001年   4篇
  2000年   6篇
  1999年   4篇
  1998年   1篇
  1997年   1篇
  1996年   4篇
  1995年   3篇
  1993年   1篇
  1991年   1篇
  1990年   5篇
  1989年   6篇
  1988年   3篇
  1986年   4篇
  1985年   2篇
  1982年   1篇
  1975年   1篇
  1966年   1篇
  1965年   1篇
排序方式: 共有761条查询结果,搜索用时 15 毫秒
11.
The purpose of this study was to compare facial growth in patients with unilateral complete cleft lip and palate (UCLP) in whom the palate was repaired with the von Langenbeck procedure at 8 months (L-8), or the Wardill procedure at 18 months (W-18). A total of 151 unaffected subjects were used as a reference series. Sixty-one adult patients, 34 in the L-8 group and 27 in the W-18 group, were investigated clinically and with lateral skull radiography and also filled out a questionnaire about their dental condition. Multiple linear regression was used to analyse the effects of the surgical strategy, sex, and the presence of a velopharyngeal flap on several dependent variables indicating sagittal jaw relations, vertical jaw relations, and inclination of incisors. The UCLP group was characterised by a short (n-sp) and retrusive maxilla (s-n-ss) and a retrusive mandible for women (s-n-sm), larger maxillary inclination (NSL/NL), more retroclined lower incisors (ILI/ML), shorter upper facial heights (n-sp) and normal total face height (n-gn) than the reference group. In the UCLP group there were significant differences between men and women in mandibular prognathism (s-n-sm), maxillary/mandibular relations (ss-n-sm), maxillary inclination (NSL/NL), total anterior facial height (n-gn), and upper anterior facial height (n-sp). Lateral crossbite was found in 20% of the UCLP group. The prevalence was similar in the L-8 and W-18 groups. Almost 80% of the patients in the UCLP group considered that their dental condition was good. The choice of surgical strategy had no significant influence on the variables measured on facial morphology.  相似文献   
12.
Due to the extreme pore volume and valuable surface area, zeolitic imidazole frameworks (ZIFs) are promising vehicles that enhance the delivery of therapeutic agents to tissues. Furthermore, these nanoporous materials have high stability in the pH and temperature of the surrounding healthy cells (37 °C and pH = 7) and an exotic potential to deform in carcinogenic environment (T > 37 °C and pH ∼ 5.5), which make them perfect smart drug delivery vehicle candidates. In this work, a series of molecular dynamics (MD) and metadynamics simulations have been performed to gain molecular insight into the mechanisms involved in the process of co-loading of doxorubicin (DOX) and EpiGalloCatechin-3 Gallate (EGCG) on ZIF-8, which form a smart drug delivery system (SDDS). The obtained results revealed that DOX was adsorbed on the carrier mostly through electrostatic interactions (Ecoul = ∼−1200 kJ mol−1, Etot = −1700 kJ mol−1), and EGCG was stacked on ZIF-8 mainly via van der Waals interactions (EL-J = ∼−600 kJ mol−1, Etot = ∼−1200 kJ mol−1). It is worth mentioning that the drug–drug L-J interactions (EL-J = ∼500 kJ mol−1) were also important in the co-loading process. The insertion of DOX and EGCG as additive agents to the initial ZIF-8/EGCG and ZIF-8/DOX systems led to the enhancement of the drug–carrier pair interactions to about ∼−2300 kJ mol−1 and ∼−2000 kJ mol−1, respectively. This finding implied that the drug–drug interactions had a complementary role in the development of SDDS via ZIF-8. From the metadynamics simulation, it was found that the geometry of the drugs is a determining factor in an efficient co-loading SDDS.

Adsorption free energy of a molecule depends on where and how the molecule meets ZIF-8 surface.  相似文献   
13.
Bliwise DL  Ansari FP 《Sleep》2007,30(7):881-884
STUDY OBJECTIVE: Many people use dietary supplements or herbal products to help them sleep. We analyzed the associations between melatonin use and insomnia and between valerian use and insomnia in a representative sample of the United States population. DESIGN AND PARTICIPANTS: The data reported upon here were collected in the 2002 Alternative Health/Complementary and Alternative Medicine (CAM) Supplement to the National Health Interview Survey. This was a survey of 31,044 personal interviews that constituted an age-representative and socioeconomically representative sample of the civilian noninstitutionalized population of the United States. RESULTS: Of the survey sample, 5.9% used valerian and 5.2% used melatonin. Of those using valerian, 29.9% endorsed insomnia as 1 reason for CAM use, and, of melatonin users, 27.5% endorsed insomnia as 1 reason for CAM use. Relatively greater use occurred in individuals under age 60 years. The decision to use such substances was made in consultation with a health care provider less than half of the time. CONCLUSIONS: Large segments of the United States population used valerian or melatonin for insomnia within the year preceding the survey, and usage typically fell outside the purview of the health care system.  相似文献   
14.
The 4- to 6-year outcome of orthograde retreatment was assessed for Phases I and II of the Toronto Study. In total, 523 teeth in 444 patients were retreated. With 395 teeth lost to follow-up and 25 extracted, 103 teeth (34% recall) were examined by two independent, blinded, calibrated examiners for outcome: "healed" (absence of apical periodontitis, signs, or symptoms) or "diseased" (presence of apical periodontitis, signs, or symptoms). The "healed" rate (81%) differed significantly for preoperative apical periodontitis (absent, 97%; present, 78%) and perforation (absent, 89%; present, 42%). Logistic regression revealed an increased risk of disease for preoperative perforation and adequate root filling quality, and postoperative lack of definitive restoration (odds ratios = 26.5, 6.6, and 14.0, respectively). Without perforation, inadequate intraoperative root filling length was also identified (odds ratio = 6.8). This study suggested that apical periodontitis, although a strong predictor, was secondary to preoperative perforation and root filling quality, and to postoperative restoration, in predicting the outcome of retreatment.  相似文献   
15.
Both subsets of MCs including MCTC (tryptase‐positive, chymase‐positive) and MCT (tryptase‐positive, chymase‐negative) are present in the testis and epididymis. Increased number of MCs, higher levels of MC‐released tryptase in testis and seminal plasma of males with fertility problems, and promoting sperm motility in individuals with oligozoospermia after using MC blockers provide evidence that MCs may play a role in male infertility/subfertility disturbances. MC‐released tryptase and histamine contribute to the fibrosis and may disrupt spermatogenesis. MCs not only influence the process of spermatogenesis but also have effects on the function of other testis‐residing cells. MC‐derived histamine may influence the steroidogenesis of Leydig cells by acting through H1R and H2R receptors. Additionally, the interaction between MC‐released ATP and P2X receptors expressed on the peritubular cells may induce the production of the pro‐inflammatory mediators by peritubular cells. Further investigations showed that MCs may be involved in the pathology of female infertility during implantation, pregnancy, and abortion. In the uterus, MCT subtype is abundant in myometrium and adjacent basal layer while MCTC subtype is distributed in all layers. MCs in response to hormones mainly estradiol and progesterone become activated and release a wide range of mediators including histamine, VEGF, proteases, and metalloproteinases (MMPs) that have a role in different stages of pregnancy. An increasing influx of MCs to the cervix during the pregnancy occurs that helps to the physiologic cervical ripening. While MMPs degrade the extracellular matrix (ECM), VEGF modulates neovascularization and histamine influences the embryo implantation. MC‐derived histamine may have a positive effect during implantation due to its participation in tissue remodeling. MC proteases including tryptase and chymase activate the precursors of MMP2 and MMP9 to mediate ECM degradation during the physiologic menstrual cycle. There is a line of evidence that MCs have a role in abortion by releasing TNF‐α.  相似文献   
16.
Although thorough studies on the immune reponse to rubella have been performed, less attention has been given to the cellular mechanism and mediators that shape the process. Specifically, information concerning the nature ofcytokine patterns involved in the immune response to Rubella vaccination is not avaliable. This study deals with cytokine production patterns of spleen cells from Balb/c mice following vaccination with the Takahashi strain of Rubella vaccine. Mice were injected intraperitonealy with Rubella virus and PBS and 7, 10 or 14 days later, spleen cells were separated and cultured with varying doses of virus, con A or only the medium. ELISA assays were performed on supernatants for measurement of IL-4, INF-gamma and IL-5. LTT (Lymphocyte Transformation Test) was also performed. The data indicate variation in cytokine patterns during the time periods after vaccination. On day 7 a type 1 pattern was observed. The LTT response was also indicative of CMI (Cell Mediated Immunity) response on the 7th and 14th days while a transient suppression on day 10 was observed. These results indicate a time dependent cytokine response with variation ultimately leading o a dominant type 1 (Ti) cytokine response.  相似文献   
17.
18.
BACKGROUND: A parental history of cardiovascular disease has a strong relationship with risk factor clusters in the offspring. This study was performed to identify major cardiovascular risk factors in middle school-aged children and their parents in both high and low-risk families. DESIGN: A school-based, cross-sectional study. METHODS: The middle schools of the 6th district of Tehran were divided randomly into two groups. A total of 169 high-risk children with their families were recruited from the first group and 105 low-risk children with their families were recruited from the second group of schools. Anthropometric and metabolic measurements were performed. RESULTS: The means of the waist circumference and waist-to-hip ratio were significantly higher in high-risk fathers. The means of total and low-density lipoprotein (LDL) cholesterol were significantly higher in both parents and children of the high-risk group. The means of the fasting plasma glucose were significantly higher in fathers and offspring of high-risk families. More fathers in high-risk families were smokers. The prevalence of increased total cholesterol, LDL-cholesterol and hyperglycemia (> or = 100 mg/dl) were higher in high-risk parents and children. The prevalence of increased body mass index (> or = 25 kg/m for parents and 85th percentile for children) was higher in fathers and children of high-risk families. CONCLUSIONS: Cardiovascular risk factors are more prevalent and clustered in high-risk families. The screening of high-risk families is essential to prevent the progression of atherosclerosis from childhood and reduce the burden of cardiovascular disease in adulthood.  相似文献   
19.
20.
Objective: This study was designed to assess the effects of omega-3 fatty acid supplementation on inflammatory factors, biomarkers of oxidative stress, and pregnancy outcomes among pregnant women with gestational diabetes (GDM).

Methods: This randomized, double-blind, placebo-controlled clinical trial was performed among 56 women with GDM. Subjects were randomly selected to receive either 1000?mg omega-3 fatty acid supplements (containing 180?mg eicosapentaenoic acid and 120?mg docosahexanoic acid) (n?=?27) or a placebo (n?=?27) for 6 weeks. Fasting blood samples were taken at study baseline and after 6 weeks of intervention to quantify biochemical variables. Newborn’s weight, height, head circumference, Apgar score, and hyperbilirubinemia were determined.

Results: At the end of the 6 weeks, taking omega-3 fatty acid significantly decreased serum high-sensitivity C-reactive protein (hs-CRP) (change from baseline: ?245.1?±?1570.5 versus?+?913.9?±?2329.4?ng/mL, p?=?0.03) and plasma malondialdehyde (MDA) concentrations (?0.4?±?1.3 versus?+?0.6±2.3, p?=?0.04) compared with the placebo. Supplementation with omega-3 had a low incidence of hyperbilirubinemiain newborns (7.7% versus 33.3%, p?=?0.02) and decreased newborns’ hospitalization rate (7.7% versus 33.3%, p?=?0.02).

Conclusions: Taken together, omega-3 fatty acid supplementation in GDM women had beneficial effects on maternal serum hs-CRP, plasma MDA levels, incidence of newborn’s hyperbilirubinemia, and hospitalization.  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