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   9454篇
  免费   643篇
  国内免费   34篇
耳鼻咽喉   130篇
儿科学   313篇
妇产科学   311篇
基础医学   1347篇
口腔科学   464篇
临床医学   1065篇
内科学   1814篇
皮肤病学   163篇
神经病学   787篇
特种医学   210篇
外科学   803篇
综合类   65篇
一般理论   3篇
预防医学   1251篇
眼科学   99篇
药学   675篇
中国医学   32篇
肿瘤学   599篇
  2024年   15篇
  2023年   100篇
  2022年   177篇
  2021年   265篇
  2020年   249篇
  2019年   282篇
  2018年   351篇
  2017年   277篇
  2016年   255篇
  2015年   328篇
  2014年   367篇
  2013年   517篇
  2012年   796篇
  2011年   819篇
  2010年   430篇
  2009年   391篇
  2008年   669篇
  2007年   639篇
  2006年   564篇
  2005年   547篇
  2004年   498篇
  2003年   453篇
  2002年   407篇
  2001年   52篇
  2000年   33篇
  1999年   53篇
  1998年   59篇
  1997年   56篇
  1996年   37篇
  1995年   49篇
  1994年   43篇
  1993年   46篇
  1992年   20篇
  1991年   21篇
  1990年   18篇
  1989年   9篇
  1988年   19篇
  1987年   15篇
  1986年   17篇
  1985年   25篇
  1984年   18篇
  1983年   16篇
  1982年   8篇
  1981年   11篇
  1980年   13篇
  1979年   13篇
  1978年   11篇
  1975年   6篇
  1974年   8篇
  1971年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Objectives:  The aim of this article is to explore socioeconomic inequalities in the psychological characteristics (psychological well-being, perceived mental health status) and perceived quality of life among cardiac patients. Methods:  A structured interview was conducted with 362 patients (32% women, mean age 56 ± 7.3 years) referred for coronary angiography. The GHQ-28 was used to measure psychological well-being, the SF-36 for perceived mental health status. Income and education indicated socioeconomic position. Logistic regressions were employed, adjusted for age, gender, functional status and severity of disease. Results:  Patients with low income or education had a higher probability of having poor psychological well-being compared to participants with high income or education (OR 5.5,CI 2.32-12.80; OR 3.1,CI 1.52-6.37 resp.), and were also more likely to have worse mental health status (OR2.9,CI 1.02-8.51;OR 4.8,CI 1.36-16.99 resp.), and low quality of life (OR 2.9,CI 1.02-8.51; OR 4.8,CI 1.36-16.99 resp.). Conclusions:  Socioeconomic status was found to be negatively associated with the psychological outcomes and quality of life among cardiac patients. Socioeconomic inequalities should be taken into account when designing suitably-adapted interventions focusing on psychosocial factors among cardiac patients. Submitted: 27 September 2007; revised: 08 January 2009, 16 March 2009; accepted: 18 March 2009  相似文献   
942.
Objective. To estimate the costs associated with formal and self-managed daily practice teams in nursing homes.
Data Sources/Study Setting. Medicaid cost reports for 135 nursing homes in New York State in 2006 and survey data for 6,137 direct care workers.
Study Design. A retrospective statistical analysis: We estimated hybrid cost functions that include team penetration variables. Inference was based on robust standard errors.
Data Collection. Formal and self-managed team penetration (i.e., percent of staff working in a team) were calculated from survey responses. Annual variable costs, beds, case mix-adjusted days, admissions, home care visits, outpatient clinic visits, day care days, wages, and ownership were calculated from the cost reports.
Principal Findings. Formal team penetration was significantly associated with costs, while self-managed teams penetration was not. Costs declined with increasing penetration up to 13 percent of formal teams, and increased above this level. Formal teams in nursing homes in the upward sloping range of the curve were more diverse, with a larger number of participating disciplines and more likely to include physicians.
Conclusions. Organization of workforce in formal teams may offer nursing homes a cost-saving strategy. More research is required to understand the relationship between team composition and costs.  相似文献   
943.
944.

Background  

Food handlers have a very important role in preventing food contamination during its preparation and distribution. This responsibility is even greater in hospitals, since a large number of patients have low immunity and consequently food contamination by pathogenic bacteria could be particularly harmful. Therefore, a good working environment and periodic training should be provided to food handlers by upper management.  相似文献   
945.
Pain that accompanies neuropathy is difficult to treat. Analgesics administered as monotherapies possess low activities in relieving this kind of pain.The effect of the simultaneous administration of indomethacin (a preferential inhibitor of cyclooxygenase-1; COX-1) or celecoxib (a relatively selective inhibitor of cyclooxygenase-2; COX-2), with selective antagonists of bradykinin2 (B2) bradykinin1 (B1) receptors (HOE 140 or des-Arg10-HOE 140) on the eleviation of diabetic and toxic neuropathic pain was investigated.Pretreatment with indomethacin (0.1 mg/kg, sc) increased the antihyperalgesic activity of low daily doses of HOE 140 or des-Arg10HOE 140 (70 nmol/kg, ip) in a diabetic (streptozotocin(STZ)-induced) neuropathy/hyperalgesia experimental model. Premedication with celecoxib before HOE 140 or des-Arg10HOE 140 administration resulted in a gradual reduction of STZ hyperalgesia. Furthermore, on days 23–24, almost complete abolishment of STZ hyperalgesia was observed. After cessation of drug administration, hyperalgesia quickly returned to the baseline threshold.The results of this study suggest that inhibitors of cyclooxygenases can increase the antihyperalgesic activity of selective antagonists of B2 and B1 receptors in diabetic and toxic neuropathic pain models. These observations may be clinically relevant.  相似文献   
946.
Neuropathic pain is difficult to treat. Classic analgesics (i.e., opioid receptor agonists) usually possess low activity. Therefore other agents such as antidepressants, anticonvulsants, and corticosteroids are used. It is commonly known that NMDA antagonists increase analgesic activity of opioids. Unfortunately, clinical use of NMDA antagonists is limited because of the relatively frequent occurrence of adverse effects e.g., memory impairment, psychomimetic effects, ataxia and motor in-coordination. Magnesium ions (Mg2+) are NMDA receptor blockers in physiological conditions. Therefore, in this study the effect of opioid receptor agonists and the influence of Mg2+ on the action of opioid agonists in vincristine-induced hyperalgesia were examined. Opioid agonists such as morphine (5 mg/kg, ip), and fentanyl (0.0625 mg/kg, ip), as well as the partial agonist buprenorphine (0.075 mg/kg, ip) administered alone on 5 consecutives days did not modify the hyperalgesia in vincristine rats. In contrast, pretreatment with a low dose of magnesium sulfate (30 mg/kg, ip) resulted in a progressive increase of the analgesic action of all three investigated opioids. After discontinuation of drug administration, the effect persisted for several days.  相似文献   
947.
This work aimed to produce a new calcium alginate-Capsul edible film with antioxidant incorporated in matrix. The vitaminic stability was evaluated in the films during their storage under different conditions for 140 days. The films were characterized with respect to their mechanical properties and surface morphology. The results indicated a 25.6% of vitamin C incorporation in matrix during the film preparation. The films stored under refrigeration in the dark did not show a decrease in the vitaminic retention. The films stored under room temperature in the dark and in the bright/dark cycles exhibited significant decreases in the vitamin retaining from the 84th and 70th days, respectively. The vitamin C addition significantly decreased the tensile strength in the new pellicle. The results of the microscopy revealed a cohesive matrix in the new edible films. These results support the utilization of the new pellicle to protect ingredients, although more studies are necessary.  相似文献   
948.
Chitosan, a biodegradable and biocompatible polysaccharide, is a potentially useful material in various fields. We produced mono and bilayer chitosan films containing dexamethasone as a drug carrier for controlled release. The chitosan drug-loaded films were produced by a casting/solvent evaporation technique using 2 wt% acetic acid solution and distilled water and they were dried at room temperature. These films were characterized by release and swelling studies, DSC and ATR-FTIR. The total profile for water absorption was similar for the types of films developed. ATR-FTIR analysis showed little change in the band position of the O--H and N--H stretching from dexamethasone and chitosan, respectively. DSC analysis from bilayer film indicates that the dexamethasone peak was shifted from 256 to 240 degrees C. These results suggested an interaction between hydroxyl and amino groups of chitosan and hydroxyl groups of dexamethasone. In the drug release studies it was observed 89.6% release from the monolayer film in 8h and 84% from the bilayer film in 4 weeks. These results suggested that the chitosan sheet prepared in this study is a promising delivery carrier for dexamethasone.  相似文献   
949.
The purpose of this study was to evaluate bioequivalence of two commercial 8 mg tablet formulations of ondansetrona available in the Brazilian market. In this study, a simple, rapid, sensitive and selective liquid chromatography-tandem mass spectrometry method is described for the determination of ondansetron in human plasma samples. The method was validated over a concentration range of 2.5-60 ng/ml and used in a bioequivalence trial between orally disintegrating and conventional tablet ondansetron formulations, to assess its usefulness in this kind of study. Vonau flash (Biolab Sanus Farmacêutica, Brazil, as test formulations) and Zofran (GlaxoSmithKline, Brazil, as reference formulation) were evaluated following a single 8 mg dose to 23 healthy volunteers of both genders. The dose was administered after an overnight fast according to a two-way crossover design. Bioequivalence between the products was determinated by calculating 90% confidence interval (90% CI) for the ratio of C(max), AUC(0-t) and AUC(0-infinity) values for the test and reference products, using logarithmically transformed data. The 90% confidence interval for the ratio of C(max) (87.5-103.8%), AUC(0-t) (89.3-107.2%) and AUC(0-infinity) (89.7-106.0%) values for the test and reference products is within the 80-125% interval, proposed by FDA, EMEA and ANVISA. It was concluded that two ondansetron formulations are bioequivalent in their rate and extent of absorption.  相似文献   
950.
Immunoglobulin (Ig) isotype switching is a recombination event that changes the constant domain of antibody genes and is catalyzed by activation-induced cytidine deaminase (AID). Upon recruitment to Ig genes, AID deaminates cytidines at switch (S) recombination sites, leading to the formation of DNA breaks. In addition to their role in isotype switching, AID-induced lesions promote Igh-cMyc chromosomal translocations and tumor development. However, cMyc translocations are also present in lymphocytes from healthy humans and mice, and thus, it remains unclear whether AID directly contributes to the dynamics of B cell transformation. Using a plasmacytoma mouse model, we show that AID+/− mice have reduced AID expression levels and display haploinsufficiency both in the context of isotype switching and plasmacytomagenesis. At the Ig loci, AID+/− lymphocytes show impaired intra- and inter-switch recombination, and a substantial decrease in the frequency of S mutations and chromosomal breaks. In AID+/− mice, these defects correlate with a marked decrease in the accumulation of B cell clones carrying Igh-cMyc translocations during tumor latency. These results thus provide a causality link between the extent of AID enzymatic activity, the number of emerging Igh-cMyc–translocated cells, and the incidence of B cell transformation.  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