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   3014篇
  免费   134篇
  国内免费   7篇
耳鼻咽喉   59篇
儿科学   67篇
妇产科学   32篇
基础医学   605篇
口腔科学   158篇
临床医学   351篇
内科学   517篇
皮肤病学   119篇
神经病学   210篇
特种医学   119篇
外科学   347篇
综合类   29篇
预防医学   161篇
眼科学   62篇
药学   200篇
中国医学   4篇
肿瘤学   115篇
  2022年   29篇
  2021年   58篇
  2020年   31篇
  2019年   37篇
  2018年   29篇
  2017年   35篇
  2016年   39篇
  2015年   56篇
  2014年   55篇
  2013年   74篇
  2012年   115篇
  2011年   116篇
  2010年   60篇
  2009年   78篇
  2008年   136篇
  2007年   146篇
  2006年   151篇
  2005年   152篇
  2004年   117篇
  2003年   161篇
  2002年   135篇
  2001年   109篇
  2000年   101篇
  1999年   99篇
  1998年   26篇
  1997年   37篇
  1996年   26篇
  1995年   20篇
  1993年   20篇
  1992年   51篇
  1991年   37篇
  1990年   48篇
  1989年   54篇
  1988年   38篇
  1987年   32篇
  1986年   34篇
  1985年   33篇
  1984年   22篇
  1979年   20篇
  1976年   21篇
  1974年   24篇
  1973年   21篇
  1972年   21篇
  1970年   22篇
  1885年   18篇
  1880年   32篇
  1879年   21篇
  1877年   21篇
  1876年   21篇
  1875年   18篇
排序方式: 共有3155条查询结果,搜索用时 15 毫秒
991.
992.
993.
Postpartum anxiety is a condition of concern due to associated difficulties for the mother, her relationships, and her infant’s development. We revised one measure of postpartum anxiety symptoms, the Postpartum Worry Scale (PWS) to include items that tap concerns related to infant health and development, important potential domains of postpartum worry. This study presents the initial phase of validation for the PWS-R. An online sample of 1,231 mothers of infants ages birth to 24 months completed the PWS-R as well as a battery of measures. We conducted a split-sample confirmatory factor analysis (CFA) to assess the latent factor structure, and a series of models were tested to refine the measure. The newly constructed factors were correlated with theoretically similar measures to test the construct validity. Initial model testing revealed a four-factor structure (i.e., Relationships, Household, Time Allocations, and Health and Development) that included 13 items. Two-group CFA confirmed the latent factor structure. Theoretically similar measures correlated moderately with the newly created PWS-R factors. The psychometric findings for the PWS-R provide preliminary support for its use as a measure of postpartum worry. Next steps in the iterative validation process are considered. Recommendations for the PWS-R’s use in clinical and research contexts are discussed.  相似文献   
994.
Streptococcus pneumoniae (S. pneumoniae) may cause severe and lethal infections months and years following stem cell transplantation (SCT). In a prospective survey over a 3.5-year period, we assessed the incidence, risk factors and outcome for invasive pneumococcal infection (IPI) following SCT. Fifty-one episodes of IPI were reported: 43 episodes after bone marrow transplantation (BMT) and 8 after peripheral blood stem cell transplantation (PBSCT); 35 after allogeneic SCT and 16 after autologous SCT. Seven IPI episodes, all bacteraemias, were defined as early, occurring 1-35 d (median 3 d) post transplantation. Forty-four episodes were defined as late (> or = 100 d post SCT), occurring 4 months to 10 years (median 17 months) post transplantation. The incidences of early and late IPI were 2.03/1000 and 8.63/1000 transplantations respectively (P = 0.001). A higher incidence of late IPI was observed after BMT than after PBSCT (10.99 versus 3.23/1000; P < 0.01) and after allogeneic versus autologous SCT (12.20 versus 4.60/1000; P < 0.01). There was a higher estimated incidence of IPI in allogeneic patients with than in those without graft-versus-host disease (GVHD) (18.85 versus 8.25/1000; P = 0.015). The mortality rate was 20%, including 2/7 of early and 8/44 of late IPI. S. pneumoniae is a rare but important complication during the aplastic phase after SCT. In conclusion, S. pneumoniae is a significant cause of morbidity late post-transplantation, especially in allogeneic patients, and particularly those with GVHD. The high IPI mortality rate, both early and late post-transplantation, requires preventive approaches, mainly effective immunization.  相似文献   
995.
Purpose Combining anthracyclines and taxanes are to date the most active cytotoxic treatment option in the neoadjuvant and palliative therapy of breast cancer patients. Adding trastuzumab to these cytotoxic agents can improve outcome for women with human epidermal growth factor receptor 2 (HER2)-overexpressing advanced breast cancer. We conducted a pilot study of preoperative epidoxorubicin and docetaxel plus trastuzumab in outpatient patients suffering from breast cancer.Patients and methods Fourteen consecutive patients were enrolled in this prospective clinical pilot trial. Preoperative treatment consisted of weekly trastuzumab (4 mg/kg body-weight loading dose, 2 mg/kg/week maintenance dose), in combination with weekly epidoxorubicin (30 mg/m2 body surface area [BSA]) and docetaxel (35 mg/m2 BSA) once a week for 6 weeks followed by 1 week off therapy.Results Patients received a total of 30 cycles (median: 2 cycles, range: 2–3 cycles) of this therapeutic regimen. Outpatient epidoxorubicin and docetaxel plus trastuzumab were well tolerated. A major response to this preoperative therapy regimen could be demonstrated in 12 of 14 patients (86%) leading to breast-conserving surgery in 11 of 14 patients (79%).Conclusions We conclude that outpatient epidoxorubicin and docetaxel plus trastuzumab are safe in the neoadjuvant treatment of patients suffering from breast cancer, based on a favorable side-effect and activity profile. Thus, this regimen can be considered for further clinical trials.Work under the Auspices of CLEXO (Center of Excellence for Clinical and Experimental Oncology)  相似文献   
996.
Arterial stiffening is the major cause of increasing systolic blood pressure in arterial hypertension. Increased arterial stiffness is one major mechanism responsible for morbidity and mortality in hypertension. A C825T polymorphism was identified in the gene encoding the G-protein beta3 subunit (GNB3), and an association of the T-allele with hypertension was demonstrated in several studies. In order to identify a pathogenetic link between hypertension and arterial stiffness, we compared two indices of arterial stiffness, pulse wave velocity (PWV) and augmentation index, in young, healthy men with and without the 825T-allele under resting conditions. PWV was determined from pressure tracing over carotid and femoral arteries in 99 subjects (CC: n=43; CT&TT: n=56). Augmentation index was derived in 72 subjects (CC: n=30; CT&TT: n=42) by pulse wave analysis using radial applanation tonometry. Carriers of the 825T-allele exhibited a significantly higher PWV compared to subjects with the CC genotype (6.0+/-0.1 m/s (TC&TT) vs 5.7+/-0.1 m/s (CC); P=0.0251). There was also a significant difference (P = 0.0448) in augmentation index between carriers of the T-allele (CT&TT: 3.4+/-2.9%) and controls with the CC -genotype (-5.0+/-4.1 %). There was no difference in any other anthropometric (age, height, weight, body mass index) or haemodynamic (heart rate, peripheral and central blood pressure). In summary, the C825T polymorphism is associated with higher arterial stiffness in young, healthy males. Arterial stiffening may pathogenetically contribute to the development of hypertension in carriers of the T-allele.  相似文献   
997.
GH deficiency (GHD) in patients with myelomeningocele leads to the question of whether these disabled patients should be treated with human GH. To date, only a few short-term reports of GH therapy are available in the literature, and long-term data for final height are lacking. We report auxological and laboratory data for seven prepubertal myelomeningocele patients with proven GHD (idiopathic GHD or neurosecretory dysfunction) during GH treatment. All patients (five males and two females; median chronological age, 6.6 yr) had shunted hydrocephalus and were treated with GH (0.5 IU/kg x week; 0.15 mg/kg x week; daily sc injections) over a median period of 38 months (range, 35-49 months). GH secretion was analyzed by measurement of spontaneous overnight GH secretion and two standard stimulation tests. Auxological parameters, bone age, serum levels of insulin-like growth factor I and insulin-like growth factor-binding protein-3, and neurological and orthopedic status were documented regularly. Median growth velocity of supine length improved during treatment (at start, 3.7 cm/yr; after 36 months, 5.7 cm/yr; P < 0.05), with highest levels 6 months after the start of therapy (8.1 cm/yr). The growth velocity of arm span was greater than these values. Supine length SD score for chronological age increased from -4.71 (at start) to -3.35 (after 36 months; P = NS), length SD score for bone age increased from -2.70 to -2.23 (P = NS), and arm span SD score increased from -2.98 to -1.75 (P < 0.05). The growth velocities of length and arm span remained significantly above the pretreatment values (P < 0.05). Symptomatic tethered cord associated with progression of scoliosis developed in two of seven children. GH treatment significantly improved the growth velocities of body length and arm span. However, the increase in length SD score was not significant, whereas arm span SD scores significantly improved over the study period.  相似文献   
998.
Objective: Asthma is a common chronic disease with various phenotypes and therapeutic responses. Unlike other diseases, current anti-inflammatory treatment with corticosteroids does not include any reference to biological measures which may vary among different asthma phenotypes. Morbidity from uncontrolled asthma suggests a need for specific targeted treatment approaches such as biologic medications. In half of asthmatics, chronic airway inflammation may be driven by T helper (Th)-2 cells, which release pro-inflammatory cytokines, such as interleukin (IL)-4, IL-5 and IL-13, contributing to eosinophil inflammation and IgE production. Earlier studies of cytokine-targeted biologic therapy on non-phenotyped asthma patients were generally not clinically effective. Methods: Literature published from 1958–2013 was identified through PubMed using the search terms which included asthma and therapy. A total of 32 studies were reviewed covering both pediatric and adult asthmatics and included double-blind randomized placebo-controlled trials testing efficacy of biologic agents to treat asthma. Results: More recent approaches to personalized medicine with expression profiling studies, genetic analysis and clinical biomarkers of Th2 inflammation have allowed identification of asthma phenotypes including a Th2 “high” phenotype. Studies targeting IgE, IL-5, IL-13 and the IL4 receptor alpha chain have shown some efficacy in phenotyped patients. For those without evidence of Th2 inflammation, no specific therapies have been identified. Conclusions: In recent years, the identification of Type-2 cytokine “high” asthma in numerous studies has predicted the clinical response to the Th2 associated therapies. It is not yet clear whether all Type 2 high asthma will respond similarly to IL-4, 5 and 13 approaches.  相似文献   
999.
Objectives:To assess the frequency and characteristics (number, complexity, and distance) of head movements, and the perception of discomfort during simulated CBCT examinations in children, considering units with different patient positioning method and head immobilization device combinations.Methods:Forty children (20 boys/20 girls, age range 10–14 years) were video-recorded during simulated CBCT examinations. Children were randomly allocated to a sequence of five CBCT units: Newtom-5G, Orthophos-SL, Cranex-3Dx (patient standing/sitting), and X1. The child scored his/her discomfort perception (visual scale) and the preferred/ill-favored unit. Three observers scored the videos (20% in duplicate): child movement (yes/no), number (<3/≥3/continuous), complexity (uniplanar/multiplanar) and distance (<3 mm/≥3 mm). κ statistics provided intra-/interobserver reproducibility. Severe/extreme motion was defined based on movement characteristics. Chi-square tests assessed the frequency differences of severe/extreme motion among the units, age and operator. Logistic regression analyses with severe/extreme motion as outcome were performed.Results:The range of intra- and inter-observer reproducibility for movement observation was 0.78–0.89 and 0.61–0.64, respectively. Between 60% (Newtom-5G) and 100% (X1) of children moved during the examination. Severe/extreme motion was significantly related to unit and age. There was significantly less severe/extreme motion, when the child was in the supine position with a foam headrest as head support. The younger the child, the higher the risk for severe/extreme motion. The majority of the children preferred the unit with the supine position and a foam headrest.Conclusions:The prevalence of severe and extreme motion was associated with the unit’s patient positioning method and head immobilization devices combined, and child age.  相似文献   
1000.
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