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   1845篇
  免费   112篇
  国内免费   11篇
耳鼻咽喉   10篇
儿科学   98篇
妇产科学   57篇
基础医学   228篇
口腔科学   50篇
临床医学   119篇
内科学   305篇
皮肤病学   106篇
神经病学   116篇
特种医学   38篇
外科学   213篇
综合类   54篇
一般理论   1篇
预防医学   117篇
眼科学   128篇
药学   130篇
中国医学   13篇
肿瘤学   185篇
  2024年   2篇
  2023年   15篇
  2022年   49篇
  2021年   79篇
  2020年   43篇
  2019年   65篇
  2018年   80篇
  2017年   61篇
  2016年   63篇
  2015年   60篇
  2014年   94篇
  2013年   115篇
  2012年   176篇
  2011年   159篇
  2010年   95篇
  2009年   63篇
  2008年   106篇
  2007年   110篇
  2006年   113篇
  2005年   86篇
  2004年   57篇
  2003年   60篇
  2002年   48篇
  2001年   21篇
  2000年   12篇
  1999年   11篇
  1998年   4篇
  1997年   4篇
  1996年   4篇
  1995年   8篇
  1994年   6篇
  1993年   5篇
  1992年   6篇
  1991年   5篇
  1990年   8篇
  1989年   7篇
  1988年   6篇
  1987年   2篇
  1986年   4篇
  1985年   6篇
  1984年   8篇
  1983年   5篇
  1982年   6篇
  1981年   5篇
  1980年   2篇
  1979年   4篇
  1977年   2篇
  1970年   3篇
  1936年   2篇
  1935年   2篇
排序方式: 共有1968条查询结果,搜索用时 15 毫秒
101.
There is concern that churning in Medicaid excludes children from the accountability system for managed care because they may not meet the one-year continuous enrollment requirement. This study explores the effect of churning in measuring childhood immunization coverage rates under the current accountability system. Data were collected from administrative databases at the Centers for Medicaid and Medicare Services and 12 states with high Medicaid managed care penetration. On average in the 12 states only 39% of the children enrolled in one specific managed care plan met the continuous enrollment requirement. However, Centers for Medicaid and Medicare Services data showed that 78% of children were enrolled in Medicaid (but not the same plan) continuously for 12 months. Both plan-specific rates and overall Medicaid rates varied greatly across the states. Policies that result in churning mean that many vulnerable children fall outside of the accountability structure intended to assure that they receive necessary services.  相似文献   
102.
103.
104.
105.
106.
We performed a study on infants and children with hypothyroidism to determine the effect of hypothyroidism and its correction on components of the IGF system. A total of 35 patients were subdivided into four groups based on age and severity of the disease. Serum concentrations of immunoreactive IGF-I, free IGF-I, IGFBP-2 and IGFBP-3 were measured before and after treatment and compared to controls matched for age, sex and puberty. Baseline total IGF-I (TIGF-I) concentrations were significantly lower prior to treatment in the infants with severe hypothyroidism and increased significantly after thyroxine therapy. Baseline free IGF-I (FIGF-I) concentration was significantly lower prior to treatment in infants with severe hypothyroidism when compared to controls but did not increase significantly after treatment. In infants with severe and compensated hypothyroidism, IGFBP-3 concentrations prior to treatment were lower when compared to controls. These concentrations increased during treatment. Baseline IGFBP-2 levels did not differ from the control values in both these groups but decreased significantly after correction of the hypothyroidism. Although these changes appeared to occur with thyroxine therapy, multiple regression analysis suggested that age was a more important determinant of the changes observed in these parameters than serum thyroxine concentration. In children with acquired hypothyroidism no difference in any of these parameters was noted between hypothyroid patients and controls. TIGF-I increased significantly on thyroxine therapy, but the difference was small. No significant differences were noted in other measured parameters with thyroxine therapy. In older children with compensated hypothyroidism no significant differences were noted in any of the measured parameters in the pretreatment, post-treatment and control groups. In conclusion, although changes appear in TIGF-I, IGFBP-3 and IGFBP-2 in infants with congenital hypothyroidism when they are treated with thyroxine, age appears to be the more important determinant of these changes than does thyroxine concentration. In older children with acquired hypothyroidism, TIGF-I and FIGF-I levels were not significantly lower than in age- and sex-matched controls. After treatment only TIGF-I levels increased.  相似文献   
107.
108.
OBJECTIVE: To compare the efficacy of electrocautery with that of the suture method for achieving hemostasis of the cervical cone bed. METHODS: We performed a retrospective chart review of all patients who underwent cold-knife conization of the cervix over a 5-year period. Patients were categorized into two groups: the cautery group, in which the cone bed was electrocauterized with a hand-held electrocoagulation device; and the suture group, in which hemostasis was achieved by a continuous locking suture placed circumferentially around the cone bed. Outcome measures evaluated include estimated blood loss, operative time, and incidence of complications, including secondary hemorrhage, cervicitis, and cervical stenosis. Data were analyzed by Student t test, chi(2) test, linear regression, and multiple logistic regression where appropriate. RESULTS: There were 156 women in the cautery group and 35 in the suture group. The cautery group had significantly lower estimated blood loss (27 mL versus 101 mL; P <.01) and shorter operative time (34 versus 43 minutes; P <.01) than the suture group. The procedure-related complication rate was 6.4% in the cautery group, compared with 14.3% in the suture group (P = nonsignificant). A higher use of lateral sutures, vasopressors, and thrombotic agents was seen in the cautery group. However, even after adjusting for these variables, mean estimated blood loss (33 mL, P <.01) and mean operative time (34 minutes, P <.01) were significantly less in the cautery group than in the suture group. CONCLUSIONS: Cauterization of the cone bed is superior to suture as a method of achieving hemostasis, with significantly less blood loss and shorter operative time.  相似文献   
109.
Purpose. Sterically stabilized phospholipid micelles (SSMs) composed of poly(ethylene glycol-2000)-grafted distearoyl phosphatidylethanolamine (PEG(2000)-DSPE) are new and promising lipid-based carriers for water-insoluble drugs. This study investigates and compares sterically stabilized mixed micelles (SSMM), composed of (PEG(2000)-DSPE) plus egg-phosphatidylcholine, with SSM as a novel delivery system for improved solubilization of water-insoluble drugs using paclitaxel as a model. Methods. Paclitaxel was solubilized in SSM (P-SSM) and SSMM (P-SSMM) by coprecipitation and rehydration with isotonic 0.01M HEPES buffer, pH 7.4. After separation of excess drug by centrifugation, mean particle size and morphology of particles in the supernatant were determined by quasi-elastic light scattering and transmission electron microscopy. The solubilization potentials of SSMM and SSM for paclitaxel were determined by reverse phase high pressure liquid chromatography (RP-HPLC). Cytotoxic activity of paclitaxel in SSMM, SSM, and dimethyl sulfoxide (10% DMSO) was determined against human breast cancer cells (MCF-7). Results. Mean hydrodynamic diameter of P-SSMM and P-SSM were 13.1 ± 1.1 nm and 15 ± 1 nm (n = 3), respectively. SSMM solubilized 1.5 times more paclitaxel than SSM for the same total lipid concentration. Solubilized paclitaxel amount increased linearly with an increase in lipid concentration. A therapeutically relevant lipid concentration (15 mM) of SSMM solubilized 1321 ± 48g/ml of paclitaxel. Paclitaxel in the absence of sufficient SSM aggregated to form lipid-coated crystals. P-SSMM, P-SSM, and paclitaxel in DMSO had comparable cytotoxic activities against MCF-7 cells. Conclusions. SSMM showed increased solubilization potential compared with SSM while retaining all of its own advantages. Therefore, it can be used as an improved lipid-based carrier for water-insoluble drugs.  相似文献   
110.
Access to safe breast-feeding alternatives for HIV-infected mothers and their infants in many settings is limited. We compared the rates of early postpartum hospitalization of infants born to HIV-infected mothers using different infant-feeding practices in a large government hospital in Pune, India. From March 1, 2000 to November 30, 2001, infants born to HIV-infected mothers were followed in a postpartum clinic. All mothers had received a standard short course of antenatal zidovudine. Infant-feeding practices were assessed within 3 d of delivery, prior to postpartum hospital discharge. Sixty-two of 148 mothers (42%) were breast-feeding their infants. Eighty-six of the mothers (58%) were providing replacement feeding, primarily diluted cow, goat or buffalo milk (top feeding). Twenty-one of the 148 participating infants (14.2%) born during the study period required hospitalization within the 1st 6 mo of life and 6 infants required repeat hospitalization. All hospitalized infants were receiving replacement feeding with a rate of 0.093 hospitalizations per 100 person-days (95% CI, 0.062 to 0.136). The reasons for hospitalization included acute gastroenteritis (48.1%), pneumonia (18.5%), septicemia (11.1%) and jaundice (11.1%). A high risk for early postpartum hospitalization was seen in replacement-fed infants born to HIV-infected mothers in Pune, India. In settings such as India, where access to safe replacement feeding is limited, interventions making exclusive breast-feeding safer for HIV-infected mothers and infants are needed. Such interventions would be valuable additions to the very effective national prevention programs that currently rely on the provision of short-course zidovudine and nevirapine.  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