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   1737篇
  免费   81篇
  国内免费   9篇
耳鼻咽喉   20篇
儿科学   24篇
妇产科学   24篇
基础医学   256篇
口腔科学   117篇
临床医学   134篇
内科学   402篇
皮肤病学   24篇
神经病学   169篇
特种医学   62篇
外国民族医学   2篇
外科学   212篇
综合类   6篇
预防医学   172篇
眼科学   16篇
药学   96篇
中国医学   11篇
肿瘤学   80篇
  2024年   2篇
  2023年   13篇
  2022年   24篇
  2021年   64篇
  2020年   36篇
  2019年   49篇
  2018年   55篇
  2017年   45篇
  2016年   39篇
  2015年   69篇
  2014年   85篇
  2013年   103篇
  2012年   135篇
  2011年   146篇
  2010年   93篇
  2009年   70篇
  2008年   127篇
  2007年   129篇
  2006年   71篇
  2005年   93篇
  2004年   85篇
  2003年   78篇
  2002年   76篇
  2001年   9篇
  2000年   9篇
  1999年   13篇
  1998年   7篇
  1997年   13篇
  1996年   6篇
  1995年   3篇
  1994年   3篇
  1993年   6篇
  1992年   3篇
  1991年   8篇
  1990年   13篇
  1989年   5篇
  1988年   4篇
  1987年   8篇
  1986年   6篇
  1985年   4篇
  1984年   2篇
  1980年   2篇
  1977年   1篇
  1976年   1篇
  1975年   2篇
  1974年   1篇
  1973年   1篇
  1971年   2篇
  1970年   2篇
  1967年   2篇
排序方式: 共有1827条查询结果,搜索用时 15 毫秒
81.
Premature acute myocardial infarction in a child with nephrotic syndrome   总被引:3,自引:0,他引:3  
We report a case of acute myocardial infarction in a nephrotic child. A 7-year-old boy with a 4-year history of steroid-unresponsive nephrotic syndrome due to mesangial proliferation disease presented with acute vomiting and chest pain. An electrocardiogram showed ST elevation and pathological Q waves in leads consistent with anterior and septal myocardial infarction. Subsequent cardiac catheterization showed no evidence of atherosclerotic coronary artery disease, and thrombotic occlusion of the anterior descending coronary artery was the likely cause of the event. Myocardial scintigraphy showed extensive myocardial damage. The child had no long history of extreme hypercholesterolemia or hypertriglyceridemia. The case suggests that children with long-lasting nephrotic syndrome may be at increased risk for ischemic cardiovascular events, due to hyperlipidemia as well as a hypercoagulability state. The literature is reviewed regarding the relationship between nephrotic syndrome and the incidence of ischemic heart disease. Received: 2 May 2001 / Revised: 31 October 2001 / Accepted: 18 November 2001  相似文献   
82.
We investigated the role of protein kinase C in the desensitization of the angiotensin II-induced contraction of guinea pig ileum. In contrast to their antagonistic effects on enzymatic activity, both activator and blockers accelerated the dissipation of the 10(-7) M angiotensin II isometric contractile response. These agents indirectly activated maxi-K+ channels in cell-attached membrane patches from freshly dispersed myocytes bathed in high-K+ solution and clamped at -40 mV. In parallel with the contractile responses, fura 2-loaded myocytes bathed in Tyrode solution showed additive increases in [Ca2+]i in response to both angiotensin II and phorbol dibutyrate (PDB). The PDB-promoted increase of the rate of angiotensin II desensitization was completely abolished by pretreatment of the tissue strips with 93 nM iberiotoxin or 8 mM KCl. Thus, we conclude that protein kinase C modulators promote faster angiotensin II desensitization by recruiting maxi-K+ channels and inducing membrane repolarization rather than by affecting the protein kinase C activity.  相似文献   
83.
84.
Attention to emotional health should be given at any circumstances of human beings development. It is especially necessary when an individual is ill and feels fragile, afraid, uncomfortable and anxious due to hospitalization. In this paper, we present an experience in which group work was used as a strategy of assistance to patients in the hospital, aiming at the implementation of an emotional assistance plan. The trajectory of the group, as well as the characteristics of the work done and its peculiarities are shown in this study. Results indicate that group work is a valuable tool for planning emotional care to these patients. However, it requires specific preparation and knowledge of group dynamics on the part of nursing professionals, so that the "healing" potential of group work can be better used.  相似文献   
85.
86.
Carotenoids are exclusively transported by lipoproteins; in vitro studies suggest that they might protect these particles against oxidation. Little is known about the factors that govern the distribution of these micronutrients among lipoproteins. The objective of this study was to assess whether carotenoids are exchanged between lipoproteins and what factors, if any, were involved. In the first experiment, different groups of trout were fed for five days with either a carotenoid-free diet or with diets containing 80 mg pure carotenoid per kilogram of feed. Lipoproteins were separated by ultracentrifugation and carotenoid-rich, high-density lipoproteins (HDL) were incubated for two hours at 37 degrees C with carotenoid-free, very low-density lipoproteins (VLDL), and vice versa. After incubation, lipoproteins were re-separated and carotenoids were quantified to measure the transfer. The same experiments were done in the presence of cholesteryl ester transfer protein (CETP) and lecithin cholesterol acyltransferase (LCAT) inhibitors. In a second experiment, the exchange was measured between human VLDL and HDL. In trout, incubation of carotenoid-rich HDL with carotenoid-free VLDL resulted in the appearance of carotenoids in VLDL, and inversely. The higher the hydrophobicity of a carotenoid, the lower its proportion in HDL after incubation. CETP and LCAT inhibitors significantly increased the proportion of carotenoids in HDL after incubation. Results obtained with human lipoproteins showed that the xanthophyll lutein transferred between lipoproteins, but could not show any carotenes (alpha-carotene, beta-carotene, and lycopene) transfer. We conclude that carotenoids, chiefly the xanthophylls, exchange between lipoproteins. The transfer depends on plasma factor(s) sensitive to CETP and/or LCAT inhibitors.  相似文献   
87.
The Scarff-Bloom-Richardson (SBR) grade, an important prognostic factor in breast cancer, was also associated with cell proliferation, a consistent indicator of response to chemotherapy. The determination of an association between SBR grade and responsiveness would be clinically useful. We explored the influence of SBR grade on response to neoadjuvant chemotherapy in patients with invasive ductal breast carcinoma. The present study centered on 431 patients registered onto one of four prospective phase II trials. SBR grading was performed according to the Elston method on needle core biopsies prospectively collected prior to treatment from 290 patients and on residual tumour at surgery from 171 patients. The post-operative grades were then compared with those obtained at diagnosis. Univariate and multivariate analysis were used to evaluate the significance of SBR grade on response to neoadjuvant chemotherapy. Both statistical analysis revealed that SBR grade III tumours responded better to neoadjuvant treatment than SBR grade I (p<10(-6)). None of the other patient and tumour characteristics tested correlated with response. Moreover, tumour responsiveness was significantly related to changes of the SBR grade (p=7 x 10(-3)). As a conclusion, we showed that SBR grade is a strong predictive factor of response to induction chemotherapy in breast cancer, independently of the type of regimen used. The association between evolution of the histological grade following chemotherapy and response to treatment may prove valuable for clinicians as they make their decision regarding patient therapy.  相似文献   
88.
Objective. To evaluate the supraspinatus muscle radiodensity on the outlet view as an indication of a tendon tear. Design and patients. Plain radiographs and magnetic resonance imaging (MRI) examinations were obtained on both shoulders of 40 subjects aged 23–70 years, including 13 asymptomatic volunteers and 27 patients. Two readers analyzed the superior contour and the heterogeneity of the supraspinatus muscle radiodensity and compared them with the MRI findings. Results and conclusion. Significant concordances (P<0.001) were found between the assessments of the superior contour and the heterogeneity of the muscle radiodensity, respectively, on plain radiographs and MR images. For the diagnosis of a full-thickness tear, the analysis of the superior contour and the heterogeneity of the muscle radiodensity reached an accuracy of 85% and 80% respectively. Stepwise discriminant analyses showed low to moderate benefit of considering the contour and the heterogeneity simultaneously. The inter- and intraobserver agreement ranged from moderate to good. We conclude that on the outlet view, modifications in the superior contour and heterogeneity of the supraspinatus muscle radiodensity suggest a full-thickness tear. Received: 6 December 1999 Revision requested: 6 March 2000 Revision received: 5 June 2000 Accepted: 4 October 2000  相似文献   
89.

Background  

In Germany, vaccination against hepatitis B is recommended for infants, children and adolescents since 1995 and for specific target groups since 1982. Little is known about knowledge about viral hepatitis and attitudes toward hepatitis B vaccination-factors likely to influence vaccine uptake.  相似文献   
90.
Nimodipine (ND) is a centrally active calcium antagonist that blocks the voltage-dependent L-type channels. Its antiepileptic properties have been proved in various animal models, including pilocarpine-induced seizures in adult rats. In order to investigate protective effects of the ND (10 (ND10) and 30 mg/kg (ND30), i.p.), young male rats (21-day-old) received ND injections before pilocarpine administration (400 mg/kg, s.c., pilocarpine group (P400)). The pretreatment with ND10 and ND30 prolonged the latencies of seizures and death on this seizure model. ND pretreatment in two doses decreased the levels of lipid peroxidation when compared to pilocarpine group. The P400 administration increased the striatal catalase activity. However, the administration of ND, in dose of 30 mg/kg, 30 min before pilocarpine, preserved catalase activity in normal levels. On the other hand, no change was detected in the animals treated with the dose of 10 mg/kg. Our results confirm the neuroprotective effect of ND on the seizures in young rats, suggesting that this drug acts positively on lipid peroxidation. Our observations shows that nimodipine cannot induces these effects via blockade of Ca(2+)-channel.  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