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   2106篇
  免费   105篇
  国内免费   4篇
耳鼻咽喉   15篇
儿科学   79篇
妇产科学   28篇
基础医学   198篇
口腔科学   38篇
临床医学   163篇
内科学   430篇
皮肤病学   34篇
神经病学   137篇
特种医学   48篇
外科学   386篇
综合类   89篇
一般理论   1篇
预防医学   94篇
眼科学   74篇
药学   238篇
中国医学   22篇
肿瘤学   141篇
  2023年   8篇
  2022年   24篇
  2021年   43篇
  2020年   33篇
  2019年   46篇
  2018年   47篇
  2017年   29篇
  2016年   51篇
  2015年   50篇
  2014年   100篇
  2013年   100篇
  2012年   187篇
  2011年   169篇
  2010年   113篇
  2009年   94篇
  2008年   133篇
  2007年   149篇
  2006年   117篇
  2005年   134篇
  2004年   132篇
  2003年   102篇
  2002年   88篇
  2001年   17篇
  2000年   17篇
  1999年   9篇
  1998年   20篇
  1997年   13篇
  1996年   14篇
  1995年   12篇
  1993年   13篇
  1992年   15篇
  1991年   8篇
  1990年   9篇
  1989年   9篇
  1988年   5篇
  1987年   12篇
  1986年   10篇
  1985年   7篇
  1984年   14篇
  1983年   7篇
  1982年   6篇
  1981年   9篇
  1980年   9篇
  1979年   3篇
  1978年   4篇
  1977年   4篇
  1975年   5篇
  1973年   2篇
  1971年   2篇
  1964年   2篇
排序方式: 共有2215条查询结果,搜索用时 62 毫秒
61.
Melioidosis is an infectious disease caused by gram-negative soil-dwelling bacillus Burkholderia pseudomallei. Musculoskeletal melioidosis mimics other infections both clinically and radiologically. An extensive literature review has been performed over musculoskeletal melioidosis through various search engines such as Pubmed, Embase, Medscape, Altavista and Google. Diagnosis requires a high index of clinical suspicion and is dependent on microbiological confirmation. Prompt treatment with long-term combination antibiotics in high dosages and surgical drainage of abscesses improves survival.  相似文献   
62.
The nervous tissue of many vertebrates, including humans, can synthesize beta-alanyl-L-histidine (carnosine). The biological functions of carnosine are still open to question, although several theories supported by strong experimental data have been proposed. The objective of this study was to examine the effects of carnosine on neurotoxicity in differentiated rat pheochromocytoma (PC12) cells. Neurotoxicity was induced by N-methyl-D-aspartate (NMDA), which caused time- and concentration-dependent cell death as measured by MTT and LDH assays. Pretreatment with carnosine significantly prevented the neurotoxicity in a concentration-dependent manner. The protective effect of carnosine was antagonized by the H1 receptor antagonist pyrilamine, but not by the H2 receptor antagonist cimetidine. In addition, alpha-fluoromethylhistidine, a histidine decarboxylase inhibitor, slightly reversed the protective action of carnosine. These results indicate that carnosine can effectively protect against NMDA-induced necrosis in PC12 cells, and its protection may in part be due to the activation of the postsynaptic histamine H1 receptor. The study suggests that carnosine may be an endogenous protective factor and calls for its further study as a new anti-excitotoxic agent.  相似文献   
63.
Breast cancer is a disease characterised by the uncontrolled growth of abnormal cells. These cancer cells can travel through the body by way of blood or lymph nodes. Previous studies have indicated that, changes in the electrical properties of abnormal breast are more significant compared to the breast normal tissues. In the present study, a simple 2D models of breast (close to realistic), with and without artificially inserted malignant cancer were simulated, based upon electrical activity within the breast. We developed an inhomogeneous female breast model, closer to the actual, by considering a breast as a hemisphere with various layers of unequal thickness in supine condition. In order to determine the potential distribution developed due to a dipole source, isotropic homogeneous conductivity was assigned to each of these compartments and the volume conductor problem was solved using finite element method. Significant changes in the potential distribution were recoded in the malignant and normal breast regions. The surface potential decreases about 0.5%, for the small malignant region of surface area 13 mm(2) (spherical diameter=2mm). And it (surface potential) decreases about 16.4% for large malignant surface area of 615 mm(2) (spherical diameter=14 mm). Hence, the results show that, the sizes of tumours result in the reduction of surface potential and follows a fourth order polynomial equation. Thus, biofield analysis yields promising results in the detection of the breast cancer of various sizes.  相似文献   
64.
65.
66.
67.
Myocardial infarction (MI) occurs more frequently in the morning as a result of the concomitant unfavorable timing of several physiological parameters and/or biochemical conditions. However, little is known about the possible influence of this circadian pattern on prognosis. To evaluate whether the time of symptom onset could potentially influence mortality from acute MI, this prospective study considered all consecutive MIs admitted to the ED of Ferrara, Italy, after a call to the Emergency Coordinating Unit from January 1, 1998, to December 31, 2001. The total sample consisted of 442 MIs (mean age, 68.7 years; males, 72%). Eighty patients (males, 82.5%) died in the ED; the remaining 362 were admitted to the hospital. Of these, 50 (males, 60%) died during their hospital stay. Based on the timing of their symptom onset, cases were categorized both into 24 1-hour intervals and four 6-hour intervals (midnight to 5:59 am, 6:00 am to 11:59 am, noon to 5:59 pm, and 6:00 pm to 11:59 pm), and the circadian distributions of fatal versus nonfatal MIs were compared. The circadian variation of MI peaked between 6:00 am and noon (P < .001), and in this period, there was a trend toward a higher frequency of fatal cases (41.5% vs. 35.2%; chi(2) = 1.911, P = .167). To verify whether this higher frequency of fatal events in the morning hours could be related to possible higher severity of cases observed in that hours, a further separate analysis considering age, infarct site, and peak levels of MB was made. Again, no significant temporal differences among the four 6-hour intervals were found between fatal and nonfatal Mis, although a trend toward older age was observed in morning MIs. Not only the frequency, but also the mortality, of acute MI could be increased in the morning hours. This could be of practical interest for emergency doctors and could have significant implications for acute treatment, because several studies have reported a lowered efficacy of thrombolytic drugs in the morning hours.  相似文献   
68.
69.
70.
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