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   3811篇
  免费   226篇
  国内免费   30篇
耳鼻咽喉   47篇
儿科学   92篇
妇产科学   102篇
基础医学   490篇
口腔科学   203篇
临床医学   289篇
内科学   933篇
皮肤病学   121篇
神经病学   287篇
特种医学   67篇
外科学   553篇
综合类   31篇
预防医学   315篇
眼科学   46篇
药学   218篇
中国医学   14篇
肿瘤学   259篇
  2023年   30篇
  2022年   74篇
  2021年   129篇
  2020年   63篇
  2019年   95篇
  2018年   122篇
  2017年   91篇
  2016年   74篇
  2015年   103篇
  2014年   165篇
  2013年   163篇
  2012年   290篇
  2011年   297篇
  2010年   184篇
  2009年   148篇
  2008年   276篇
  2007年   266篇
  2006年   211篇
  2005年   208篇
  2004年   210篇
  2003年   175篇
  2002年   171篇
  2001年   61篇
  2000年   39篇
  1999年   39篇
  1998年   24篇
  1997年   36篇
  1996年   20篇
  1995年   14篇
  1994年   13篇
  1993年   9篇
  1992年   24篇
  1991年   18篇
  1990年   19篇
  1989年   13篇
  1988年   6篇
  1987年   11篇
  1986年   14篇
  1985年   11篇
  1984年   23篇
  1983年   9篇
  1982年   8篇
  1981年   9篇
  1979年   13篇
  1976年   7篇
  1975年   7篇
  1973年   8篇
  1971年   6篇
  1968年   8篇
  1967年   6篇
排序方式: 共有4067条查询结果,搜索用时 31 毫秒
1.
We report on a 3‐year‐old girl with a microvesicular generalized rash in whom primary infection by parvovirus B19 was demonstrated by seroconversion. To our knowledge, this is the first instance of an eruption arising from parvovirus B19 with this peculiar clinical pattern.  相似文献   
2.
Clinical decisions are often made with incomplete information, yet patient care decisions are made every day. Patients vary clinically, uncertainty exists in diagnostic and prognostic information, and many preventive and treatment alternatives have not been formally assessed for their effectiveness. Because scientific information will never answer all clinical questions, clinical decisions are partially based on probabilistic information.
This paper describes how to apply clinical decision making to diagnosing and managing dental caries and periodontal diseases. By using explicit information to quantify probabilities and outcomes, clinical decision making analyzes decisions made under uncertain conditions and the uncertain impact of clinical information.
Clinical decision making incorporates concepts for preventing, diagnosing and treating dental caries and periodontal diseases: risk assessment, evidence-based dentistry, and multiple oral health outcomes. This information can serve as a tool for clinicians to augment clinical judgment and expertise.  相似文献   
3.
4.
This is a qualitative study of clinicians' use of partial information disclosure and its consequences for adolescents' ability to participate in the management of their cancer treatment. A total of 17 pediatric cancer patients, their families, and clinicians were observed during 15 months of ethnographic fieldwork in a hospital in Barcelona, Spain. Eighty-six hours of videotaped medical and social activities were analyzed micro-interactionally and longitudinally. Clinicians used 4 strategies to evade direct answers to adolescents' questions: contingent answers, narrow answers, non-answer responses, and question forestalling. Information withholding by clinicians was shown to greatly limit adolescents' ability to participate in the management of their treatment and to be ineffective in its implicit goals of protecting the patient and containing uncertainty and anxiety. The author concludes that if clinicians were to integrate adolescents' individual information needs into their communicative practices they would be able to better assess what information to disclose as well as how and when to disclose it.  相似文献   
5.
Mice pretreated with Bacillus megaterium ATCC 33085 grown on TSA medium developed a significant increase in primary antibody response to SRBC. Conversely, pretreatment with a spore suspension harvested from nutrient Agar medium decreased this antibody response. A suspension of organisms grown on a defined, phosphorus-deficient medium (P-Medium) had no effect. Otherwise, only the spore suspension was able to enhance the contact sensitivity to dinitrofluorobenzene. Peritoneal leucocyte numbers were increased by inoculation with both TSA-cultured bacteria and the spore suspension, but not by P-Medium-cultured bacteria. Administration of both the spore suspension and P-Medium-cultured bacteria decreased the in vitro phagocytosis by peritoneal adherent cells. These immunomodulator properties are discussed in relation to characteristics of the strain tested.  相似文献   
6.
PURPOSE: A laboratory investigation was undertaken to assess the effects of propofol on renal function, through modulation of the systemic inflammatory response, in an in vivo experimental model of aortic surgery in comparison with sevoflurane. METHODS: Twenty young male piglets were anesthetized with either propofol 4 mg.kg(-1).hr(-1) (n = 10) or sevoflurane 1.5% end-tidal concentration (n = 10). Animals were subjected to aorta-aortic bypass with suprarenal aortic clamping for 30 min. At specific intervals (basal -before the start of surgery; reperfusion 15 min after unclamping the aorta; at 24, 48 and 72 hr after surgery, and on the seventh day after surgery) the levels of the following were determined: plasma creatinine, renal myeloperoxidase, tumour necrosis factor-alpha, interleukin 1-ss, and interferon-gamma; kidney superoxide anion and its detoxifying enzyme superoxidase dismutase, kidney malondialdehyde and the activity of inducible nitric oxide synthase. Seven days after surgery, the animals were anesthetized using the described techniques, and after blood withdrawal and kidney sampling they were sacrificed. RESULTS: In comparison with sevoflurane, propofol was associated with a lower concentration of plasma creatinine (P < 0.05) together with lower concentrations of myeloperoxidase, tumour necrosis factor-alpha, interleukin 1-ss, interferon-gamma, superoxide anion and superoxidase dismutase, malondialdehyde and inducible nitric oxide synthase (P < 0.05). CONCLUSION: In an experimental model of aortic reconstructive surgery, and compared with sevoflurane, propofol anesthesia is associated with less neutrophil infiltration, lower plasma proinflammatory cytokine levels, lower production of oxygen free radicals, less lipid peroxidation, and reduced inducible nitric oxide synthase activity. These observations suggest a possible renal protective effect of propofol in this surgical setting.  相似文献   
7.
Since their approval in 1998, the popularity of selective cyclooxygenase-2 (COX2) inhibitors has swung from a domination of drug sales to serious disputes about their cardiovascular safety. Despite the numerous studies on COX2 inhibitors that have emerged, drawing conclusions about their cardiovascular safety has been complicated by conflicting results, underpowered clinical trials, and the lack of a placebo group and use of post hoc analyses in many trials. Nonetheless, certain conclusions can be made with reasonable accuracy. This review addresses the controversy in 3 segments. It begins with a discussion of the several mechanisms proposed to explain how selective COX2 inhibition impacts the cardiovascular system. This is followed by a recount of the several clinical studies that delved into the cardiovascular outcomes associated with COX2 inhibitors. Finally, answers to key questions are provided to assist the clinician in devising a systematic approach to the risk-benefit analysis of COX2 inhibitors in actual practice.  相似文献   
8.
The intensity dependence of the auditory-evoked potentials (IDAP) is inversely related to serotonergic tone. Depression is frequently observed after stroke, associated with cognitive impairment and increased mortality. Aim of this study was to investigate the serotonergic tone in acute stroke patients by IDAP. Consecutive patients with an acute stroke admitted in our stroke unit were evaluated using clinical and instrumental examinations and compared with healthy controls. The IDAP was calculated as the linear amplitude/stimulus intensity function (ASF) slope, by measuring the peak-to-peak amplitude of Nl-P2 on four blocks of different stimulus intensities. Twenty patients were enrolled; 11 had a right brain infarction; nine had depressive symptoms (DS). The ASF slope of the auditory-evoked potentials was markedly increased in stroke patients compared with controls ( P  = 0.021). Stroke patients with DS had a significant steeper ASF slope than controls ( P  = 0.017). There was no statistical difference in ASF slope between stroke patients without DS and controls. Post-stroke depression pathophysiology is still debated. Our study suggests that in acute stroke patients with DS, there is a direct involvement of the serotonergic system, regardless the degree of disability and the site of the lesion.  相似文献   
9.
Basic fibroblast growth factor (bFGF or FGF-2) is present in the basal membrane of pancreatic cells during the pancreatic embryonic development. The expression of bFGF receptors has been described in normal pancreatic cells. By contrast, pancreatic cancer cells express not only the bFGF receptors but also the bFGF itself. With the aim of understanding the effects induced by the production of bFGF by pancreatic cancer cells, the pancreatic acinar cell line (AR4-2J) was used. AR4-2J cells do not produce bFGF but express bFGF receptors. These cells were transfected with a vector containing the bFGF cDNA encoding the three different forms of bFGF characterized in tumor cells. Results showed that the bFGF expression induced important phenotypic and enzymatic modifications. The transfected cells lost some morphological features of the acinar cells and expressed amylase and lipase at low levels (a 90% decrease for amylase activity, whereas lipase activity was barely detectable). These results suggest that bFGF could be involved in maintaining pancreatic cells in a slightly differentiated state.  相似文献   
10.
BACKGROUND: Equilibration of hemoglobin concentration after transfusion has been estimated to take about 24 hours, but some studies have shown that earlier measurements reflect steady-state values in persons who have not bled recently. This study was aimed at assessing the changes over time in hemoglobin concentration after transfusion in acutely anemic patients because of recent bleeding. STUDY DESIGN AND METHODS: Thirty-two normovolemic patients recovering from an acute bleeding episode who were no longer thought to be bleeding and who received a 2- unit red cell transfusion were studied. At baseline and 15, 30, 60, and 120 minutes and 24 hours after transfusion, hemoglobin concentration and hematocrit values were measured. RESULTS: The administration of 2 units of packed red cells elicited a 24-hour increase of 22.4 +/− 6.8 g per L in hemoglobin concentration. Hemoglobin values were not different at any of the defined posttransfusion times. Hematocrit levels experienced similar changes over time. Agreement between 15-minute and 24-hour values was excellent, as only 6 percent of patients exhibited a clinically significant difference (> 6 g/L) between the hemoglobin measurements. CONCLUSION: Hemoglobin and hematocrit values rapidly equilibrate after transfusion in normovolemic patients who are recovering from an acute bleeding episode. This fact would allow a rapid assessment of the effects of transfusion and of the recurrence of bleeding in patients remaining at risk.  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