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   25230篇
  免费   2094篇
  国内免费   48篇
耳鼻咽喉   168篇
儿科学   846篇
妇产科学   714篇
基础医学   3248篇
口腔科学   506篇
临床医学   3725篇
内科学   4421篇
皮肤病学   292篇
神经病学   2248篇
特种医学   694篇
外科学   3120篇
综合类   602篇
一般理论   35篇
预防医学   3007篇
眼科学   422篇
药学   1641篇
  2篇
中国医学   15篇
肿瘤学   1666篇
  2022年   156篇
  2021年   392篇
  2020年   244篇
  2019年   411篇
  2018年   473篇
  2017年   374篇
  2016年   372篇
  2015年   436篇
  2014年   576篇
  2013年   980篇
  2012年   1365篇
  2011年   1508篇
  2010年   784篇
  2009年   763篇
  2008年   1322篇
  2007年   1399篇
  2006年   1399篇
  2005年   1356篇
  2004年   1390篇
  2003年   1294篇
  2002年   1191篇
  2001年   571篇
  2000年   603篇
  1999年   566篇
  1998年   302篇
  1997年   263篇
  1996年   255篇
  1995年   260篇
  1994年   201篇
  1993年   204篇
  1992年   416篇
  1991年   387篇
  1990年   417篇
  1989年   354篇
  1988年   316篇
  1987年   314篇
  1986年   312篇
  1985年   307篇
  1984年   234篇
  1983年   205篇
  1982年   141篇
  1981年   149篇
  1980年   161篇
  1979年   192篇
  1978年   167篇
  1977年   135篇
  1974年   152篇
  1973年   151篇
  1972年   141篇
  1971年   138篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
101.
102.
ISSUES AND PURPOSE. To identify the ethical and legal implications of conducting research with homeless adolescents and to discuss guidelines for conducting research without parental consent.
CONCLUSIONS. Ethical principles of capacity, risk, postponement, and truthful disclosure within the context of the rights of minors to consent to healthcare treatment form the basis of the argument for allowing adolescents to consent to participate in research without parental consent when there is minimal risk or when such consent could place them at increased risk for harm.
PRACTICE IMPLICATIONS. Adolescents who are the target population for clinical research or who are intended recipients of nursing care should be involved in setting priorities, purposes, and protocols. Parents and other adults from their communities should be included in developing strategies to protect their confidentiality and privacy while helping them achieve autonomy in making informed health-related decisions.  相似文献   
103.
OBJECTIVE: Non-steroidal anti-inflammatory drugs (NSAIDs) are routinely used after coronary artery bypass surgery (CABG), yet their effects have seldom been evaluated in randomized controlled settings. The aim of this study was to examine the efficacy and safety of a commonly used NSAID, naproxen. We hypothesized that naproxen would reduce postoperative pain following CABG without increasing complications. METHODS: Patients (N=98) undergoing primary CABG were randomized to receive naproxen (500 mg q12hX5 doses via suppository started 1h after operation, followed by oral 250 mg q8hX6 doses) or placebo. Standard analgesic and anti-emetic regimens were available to both patient groups. Interventions were double-blinded. Primary end-points were postoperative pain measured before and after chest physiotherapy by visual analog scale and pulmonary slow vital capacity (SVC). RESULTS: Baseline characteristics were equivalent between the two groups. Over the first 4 postoperative days, naproxen decreased pain by 47+/-17% on average before chest physiotherapy (P=0.034), and 44+/-13% after chest physiotherapy (P=0.0092). Patients who received naproxen also had better preservation of SVC over the first 4 postoperative days (mean loss of SVC from baseline: 2.1+/-0.1 vs. 2.5+/-0.1l, naproxen vs. placebo, P=0.0032). This was concomitant with a lower white blood cell count observed in naproxen patients (9.2+/-0.3 vs. 12.7+/-1.5x10(9)/l, naproxen vs. placebo, P=0.03). Patients who received naproxen had more chest tube drainage after 4h postoperatively, but there was no difference in the incidence or amount of transfusions. There was no difference in medication use, length of stay, or in the incidence of atrial fibrillation, azotemia, and other complications. CONCLUSIONS: Naproxen is an effective and low-cost adjunct for optimization of pain control and lung recovery after CABG. Its use may result in increased chest tube drainage, but no apparent increase in other complications.  相似文献   
104.
To determine the feasibility of increasing the calcium, protein and calorie intake of osteoporotic fracture patients by repeated dietary counselling delivered by a dietitian, a randomized controlled trial was conducted. Among 189 patients presenting with osteoporotic fractures to an Orthopaedics and Traumatology Department of a large regional hospital, 98 patients were randomized to the intervention group and 91 were randomized to the control group (with usual care). Intervention group received three sessions of dietary counselling with tailored made recommendations over a period of 4 months, while the control group only received dietary assessment and pamphlets on the prevention of osteoporosis. Almost all subjects in both intervention and control groups had calcium intake below the recommended level of 1000 mg at baseline. Half and 60% of subjects in both groups had total energy and protein intake below recommended levels respectively. The mean weights of control and intervention groups at baseline were 51.5 and 50.9 kg respectively, while the body mass index (BMI) were 22.6 (kg m(-2)) and 22.6 (kg m(-2)) respectively. After dietary intervention, significant increase of intake was seen in calcium intake (P = 0.0095 by t-test) in the intervention group. No significant increase was seen in protein or calorie intake. No significant change was observed in the body weight or BMI although there was a positive trend in the intervention group for all these parameters. We concluded that there was general malnutrition in Chinese elderly who presented with osteoporotic fractures. Dietary calcium could be increased by repeated professional dietary counselling. Future studies with longer duration and more objective clinical outcomes will be helpful to further demonstrate the long-term effects of dietary intervention on osteoporosis and other chronic diseases.  相似文献   
105.
This study investigates the efficacy of an intensive, integrated approach to stress reduction and coping enhancement directed towards an educated, upper level management population. Ninety‐five US governmental senior managers participated in a 35‐h stress management retreat held over a 3.5‐day period. The retreat combined didactic and experiential activities that were designed to increase participants' knowledge of stress liabilities and coping skills. Participants were encouraged to make positive lifestyle changes and to create specific action plans for the year following the workshop. Evaluations of participant satisfaction were completed at the close of the workshop. Eighty‐three participants completed baseline and follow‐up Stress and Coping Inventory (SCI) assessments in order to identify durable changes in these measures. Across 10 months, participants showed significant improvements in their overall Global Balance scores, psychological symptoms, depression symptoms, and all major coping scales, including Health Habits, Social Support, Responses to Stress and Life Satisfactions. Therefore, an intensive, multifaceted approach to stress intervention is a viable option for encouraging sustained behavioural change. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
106.
Research suggests that buprenorphine may possess antidepressant activity. The Beck Depression Inventory was completed at baseline and 3 months by heroin dependent subjects receiving either buprenorphine or methadone maintenance as part of a larger, pre-existing, double blind trial conducted by NDARC (Australia). Depressive symptoms improved in all subjects, with no difference between methadone and buprenorphine groups, suggesting no differential benefit on depressive symptoms for buprenorphine compared to methadone.  相似文献   
107.
Recurrent pleural effusions are common complications of hospitalized patients with human immunodeficiency virus (HIV) infection and may pose difficult diagnostic dilemmas. A common cause of recurrent pleural effusions in up to 30% of HIV-seropositive patients is pulmonary involvement by Kaposi's sarcoma, a human herpesvirus 8 (HHV 8)-related neoplasm. The pathogenesis of these effusions is unclear. These recurrent effusions, although benign, have shown significant mesothelial atypia/reactive changes of uncertain etiology. We attempted to evaluate these effusions morphologically and molecularly for the presence of HHV 8, with particular attention to mesothelial cells. All recurrent pleural effusions, as defined by any effusion tapped for cytological examination on more than two occasions, in HIV-positive patients at the National Institutes of Health were examined from 1998 to the present. Cases were stratified according to patients with and without histologically confirmed HHV 8 disease manifestations. Five patients with HHV 8 diseases (four with disseminated Kaposi's sarcoma and one with Castleman's disease) were identified. As a control group, five effusions from HIV-seropositive patients without known HHV 8-related diseases were identified. Cytological examination of effusions in patients with HHV 8-related diseases demonstrated atypical/markedly reactive mesothelial cells accompanied by a polymorphous background of lymphocytes. Molecular studies for B- and T-cell clonality in microdissected whole samples showed no definitive clones in these cases. Conversely, polymerase chain reaction (PCR) studies for the HHV 8 virus was positive in these samples. PCR studies on pure populations of microdissected mesothelial cells from the HHV 8-related effusions were positive for HHV 8 sequences, whereas those from HIV patients with non-HHV 8 related diseases were negative. Immunohistochemistry for HHV 8 (monoclonal antibody to latent nuclear antigen (LNA-1; ORF-73) on cellblock material demonstrated scattered positive mesothelial cells in three of the five cases of HHV 8-associated effusions. HHV 8 has been recently implicated in the pathogenesis of Kaposi's sarcoma and primary effusion lymphoma. Mesothelial cells in recurrent pleural effusions from patients with Kaposi's sarcoma and Castleman's disease appear to be infected with HHV 8. Additional studies need to be done to define the role of mesothelial cell infection in the pathogenesis of these HHV 8-associated effusions and define the prognostic significance.  相似文献   
108.
1. Single applications of solutions of capsaicin were made to the intact skin of anaesthetized rats and the effects on cutaneous blood flow and the firing of C-nociceptor afferents determined. Blood flow was measured by laser-Doppler flowmetry. C-fibre activity was recorded from filaments dissected from the saphenous nerve. 2. Following the application of a capsaicin solution (concentration > or = 1 mM) to rat saphenous skin, low frequency firing occurred in C-polymodal nociceptors that sometimes continued for > 10 min. At the some time, large increases in skin blood flow occurred exceeding 300% in some instances. 3. After the initial excitation, some C-polymodal nociceptors lost their sensitivity to pressure whilst their sensitivity to heat was lost or enhanced depending on the vehicle used. 4. Sensitivity of C-polymodal nociceptors to heat recovered in < 1 day following a single application of 33 mM capsaicin. Thresholds to mechanical pressure, however, were still significantly elevated by 123% on day 1, but had recovered on day 2. 5. Vasodilatation in response to saphenous nerve stimulation ('antidromic vasodilatation') was significantly reduced by 35%, 2 days after a single application of 33 mM capsaicin, but was normal at 4 days. 6. Following a single application of 33 mM capsaicin, skin substance P levels fell to only half the normal value at day 1 and remained at this level throughout the 4 day period examined. 7. It is suggested that the ability of relatively low concentrations of capsaicin to desensitize C-fibre nociceptors may underlie the analgesic action of topical capsaicin in man.  相似文献   
109.
110.
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