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   18113篇
  免费   1195篇
  国内免费   67篇
耳鼻咽喉   171篇
儿科学   401篇
妇产科学   446篇
基础医学   2702篇
口腔科学   697篇
临床医学   2112篇
内科学   3774篇
皮肤病学   348篇
神经病学   1739篇
特种医学   495篇
外科学   1836篇
综合类   106篇
一般理论   9篇
预防医学   1754篇
眼科学   259篇
药学   1378篇
中国医学   104篇
肿瘤学   1044篇
  2023年   166篇
  2022年   214篇
  2021年   495篇
  2020年   306篇
  2019年   518篇
  2018年   695篇
  2017年   495篇
  2016年   541篇
  2015年   691篇
  2014年   761篇
  2013年   1060篇
  2012年   1596篇
  2011年   1626篇
  2010年   767篇
  2009年   638篇
  2008年   1193篇
  2007年   1187篇
  2006年   1123篇
  2005年   1057篇
  2004年   1014篇
  2003年   909篇
  2002年   827篇
  2001年   135篇
  2000年   116篇
  1999年   107篇
  1998年   93篇
  1997年   82篇
  1996年   95篇
  1995年   58篇
  1994年   40篇
  1993年   42篇
  1992年   55篇
  1991年   46篇
  1990年   50篇
  1989年   35篇
  1988年   30篇
  1987年   36篇
  1986年   45篇
  1985年   35篇
  1984年   51篇
  1983年   30篇
  1982年   35篇
  1981年   44篇
  1980年   30篇
  1979年   22篇
  1978年   14篇
  1977年   13篇
  1975年   15篇
  1974年   13篇
  1970年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
This study presents a new protocol for arthroscopic approach based on the treatment of 36 patients with extension block of the knee as a result of intra-articular reconstruction of the anterior cruciate ligament (ACL) using the patellar tendon. Arthroscopy not only allowed the identification of the active mechanical extension block of the knee, but also the passive mechanical block that can occur with a functional or loose ligament. This protocol can be useful in the treatment of postoperative extension block of the knee as a complication of ACL reconstruction.  相似文献   
993.
994.
OBJECTIVES: To explore the burden of asthma on the lives of people presenting to hospital emergency departments for asthma treatment. DESIGN: A qualitative study. Consenting individuals with asthma who presented to emergency departments were interviewed in-depth, and interviews were taped, transcribed and thematically analysed. Questionnaire data on medication use, respiratory health and asthma knowledge were also collected. Asthma severity was determined from the medical records. SETTING: A tertiary teaching hospital and a suburban hospital during March and April 2000, and a rural hospital during July and August 2000. PARTICIPANTS: Sixty-two participants (19 male and 43 female), aged 18-70 years. RESULTS: The burden of asthma was broad, affecting social life, personal relationships, employment and finances. The cost of asthma medication was an issue for nearly two-thirds of participants. Individuals performed their own "cost-benefit analysis" for medication use, weighing up expense, perceived side effects and potential benefits. As a consequence, several participants chose to alter their medication dose, or not to take prescribed medications. For some participants, asthma directly contributed to diminished employment opportunities. CONCLUSIONS: To achieve a therapeutic partnership, doctors need to be aware of the substantial social, personal and financial burden of asthma for their patients. They should also recognise that patients' perceptions of treatment cost may compromise treatment adherence.  相似文献   
995.
Context  Quality of care of patients with acute myocardial infarction (AMI) has received intense attention. However, it is unknown if a structured initiative for improving care of patients with AMI can be effectively implemented at a wide variety of hospitals. Objective  To measure the effects of a quality improvement project on adherence to evidence-based therapies for patients with AMI. Design and Setting  The Guidelines Applied in Practice (GAP) quality improvement project, which consisted of baseline measurement, implementation of improvement strategies, and remeasurement, in 10 acute-care hospitals in southeast Michigan. Patients  A random sample of Medicare and non-Medicare patients at baseline (July 1998–June 1999; n = 735) and following intervention (September 1–December 15, 2000; n = 914) admitted at the 10 study centers for treatment of confirmed AMI. A random sample of Medicare patients at baseline (January–December 1998; n = 513) and at remeasurement (March–August 2001; n = 388) admitted to 11 hospitals that volunteered, but were not selected, served as a control group. Intervention  The GAP project consisted of a kickoff presentation; creation of customized, guideline-oriented tools designed to facilitate adherence to key quality indicators; identification and assignment of local physician and nurse opinion leaders; grand rounds site visits; and premeasurement and postmeasurement of quality indicators. Main Outcome Measures  Differences in adherence to quality indicators (use of aspirin, -blockers, and angiotensin-converting enzyme [ACE] inhibitors at discharge; time to reperfusion; smoking cessation and diet counseling; and cholesterol assessment and treatment) in ideal patients, compared between baseline and postintervention samples and among Medicare patients in GAP hospitals and the control group. Results  Increases in adherence to key treatments were seen in the administration of aspirin (81% vs 87%; P = .02) and -blockers (65% vs 74%; P = .04) on admission and use of aspirin (84% vs 92%; P = .002) and smoking cessation counseling (53% vs 65%; P = .02) at discharge. For most of the other indicators, nonsignificant but favorable trends toward improvement in adherence to treatment goals were observed. Compared with the control group, Medicare patients in GAP hospitals showed a significant increase in the use of aspirin at discharge (5% vs 10%; P<.001). Use of aspirin on admission, ACE inhibitors at discharge, and documentation of smoking cessation also showed a trend for greater improvement among GAP hospitals compared with control hospitals, although none of these were statistically significant. Evidence of tool use noted during chart review was associated with a very high level of adherence to most quality indicators. Conclusions  Implementation of guideline-based tools for AMI may facilitate quality improvement among a variety of institutions, patients, and caregivers. This initial project provides a foundation for future initiatives aimed at quality improvement.   相似文献   
996.
In depressed patients, sleep undergoes marked alterations, especially sleep onset insomnia, sleep fragmentation, and disturbances of the Rapid Eye Movement (REM) sleep. Abnormalities of rest-activity rhythms and of hypothalamic-pituitary-adrenocortical function have also been described in these patients. In the present study, we examined the presence of such abnormalities in a recently developed line of mice (Helpless mice-H) that exhibit depression-like behaviors in validated tests, compared to the nonhelpless (NH) line derived from the same colony. Experiments were essentially carried out in females for which previous studies showed marked differences between H and NH lines. Compared to NH mice, the H line exhibited (i) lower basal locomotor activity, (ii) sleep fragmentation, shift towards lighter sleep stages, and facilitation of REM sleep reflected by increased amounts and decreased latency, (iii) larger response to the REM sleep promoting effect of muscarinic receptor stimulation (by arecoline). In contrast, H and NH mice were equally responsive to the REM sleep inhibitory effect of 5-HT1A receptor stimulation (by 8-OH-DPAT). In addition, a deficiency in delta power enhancement after sleep deprivation was observed in the H group, and acute immobilization stress in this group failed to elicit a REM sleep rebound and was associated with a long-lasting raise in serum corticosterone levels. These results further validate H mice as a depression model and suggest they might be of particular interest for investigating the neurobiological mechanisms and possibly genetic substrates underlying sleep alterations associated with depression.  相似文献   
997.
Increasingly, Web-based data dissemination systems are being used to provide public health information. This article describes Florida's experience in augmenting a Web-based data query system, Florida CHARTS, with a geographic information system component. As with any systems development, users' needs guide the product. With a focus on community health assessment and improvement planning, several methods of data display have been established. A variety of issues are explored including the impact of small numbers of events on data display and data confidentiality, the selection of geographic units of analysis, and techniques for geographically coding data.  相似文献   
998.
PURPOSE: Plasmid DNAs encoding cytokines enhance immune responses to vaccination in models of infectious diseases and cancer. We compared DNA adjuvants for their ability to enhance immunity against a poorly immunogenic self-antigen expressed by cancer. EXPERIMENTAL DESIGN: DNAs encoding cytokines that affect T cells [interleukin (IL)-2, IL-12, IL-15, IL-18, IL-21, and the chemokine CCL21] and antigen-presenting cells [granulocyte macrophage colony-stimulating factor (GM-CSF)] were compared in mouse models as adjuvants to enhance CD8+ T-cell responses and tumor immunity. A DNA vaccine against a self-antigen, gp100, expressed by melanoma was used in combination with DNA encoding cytokines and cytokines fused to the Fc domain of mouse IgG1 (Ig). RESULTS: We found that (a) cytokine DNAs generally increased CD8+ T-cell responses against gp100; (b) ligation to Fc domains further enhanced T-cell responses; (c) adjuvant effects were sensitive to timing of DNA injection; (d) the most efficacious individual adjuvants for improving tumor-free survival were IL-12/Ig, IL-15/Ig, IL-21/Ig, GM-CSF/Ig, and CCL21; and (e) combinations of IL-2/Ig+IL-12/Ig, IL-2/Ig+IL-15/Ig, IL-12/Ig+IL-15/Ig, and IL-12/Ig+IL-21/Ig were most active; and (f) increased adjuvanticity of cytokine/Ig fusion DNAs was not related to higher tissue levels or greater stability. CONCLUSIONS: These observations support the potential of cytokine DNA adjuvants for immunization against self-antigens expressed by cancer, the importance of timing, and the enhancement of immune responses by Fc domains through mechanisms unrelated to increased half-life.  相似文献   
999.
BACKGROUND: Besides an established role for certain human papillomavirus (HPV) genotypes in the etiology of cervical cancer, little is known about the influence of multiple-type HPV infections on cervical lesion risk. We studied the association between multiple HPV types and cervical lesions among 2,462 Brazilian women participating in the Ludwig-McGill study group investigation of the natural history of HPVs and cervical neoplasia. METHODS: Cervical specimens were typed by a PCR protocol. The cohort's repeated-measurement design permitted the assessment of the relation between the cumulative and concurrent number of HPV types and any-grade squamous intraepithelial lesions (SIL) and high-grade SIL (HSIL). RESULT: At individual visits, 1.9% to 3.2% of the women were infected with multiple HPVs. Cumulatively during the first year and the first 4 years of follow-up, 12.3% and 22.3% were infected with multiple types, respectively. HSIL risk markedly increased with the number of types [odds ratio (OR), 41.5; 95% confidence interval (95% CI), 5.3-323.2 for single-type infections; OR, 91.7; 95% CI, 11.6-728.1 for two to three types; and OR, 424.0; 95% CI, 31.8-5651.8 for four to six types, relative to women consistently HPV-negative during the first year of follow-up]. The excess risks for multiple-type infections remained after exclusion of women infected with HPV-16, with high-risk HPV types, or persistent infections, particularly for any-grade SIL. Coinfections involving HPV-16 and HPV-58 seemed particularly prone to increase risk. CONCLUSION: Infections with multiple HPV types seem to act synergistically in cervical carcinogenesis. These findings have implications for the management of cervical lesions and prediction of the outcome of HPV infections.  相似文献   
1000.
Lee MY  Kim SY  Min DS  Choi YS  Shin SL  Chun MH  Lee SB  Kim MS  Jo YH 《Glia》2000,30(3):311-317
Previous in vitro studies using cell cultures or brain slices have demonstrated that phospholipase D (PLD) in the nervous system is involved in the signaling mechanism in response to a variety of agonists. However, little is known about the pathophysiological role of PLD-mediated signaling in the adult brain. We examined the changes in the expression of a PLD isozyme, PLD1, in the adult rat hippocampus, using immunological approaches and an assay for PLD activity after transient forebrain ischemia (four-vessel occlusion model) that results in the selective delayed death of CA1 pyramidal cells and induces reactive astrocytes in the CA1 subfield. In the control hippocampus, PLD1 the level of immunoreactivity was very low. After ischemia, in parallel with the results of Western blot analysis and the PLD activity assay, immunohistochemical analysis of PLD1 demonstrated that the immunoreactive proteins peaked at 7-14 days and were most prominent in the CA1 and the dentate hilar region. The temporal and spatial patterns of immunoreactivity of both PLD1 and glial fibrillary acidic protein (GFAP) were very similar, indicating that reactive astrocytes express PLD1, confirmed by double staining for PLD1 and GFAP. These results demonstrate that reactive astrocytes upregulate PLD in vivo after injury in the adult rat hippocampus.  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