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   49090篇
  免费   3434篇
  国内免费   1033篇
耳鼻咽喉   381篇
儿科学   1157篇
妇产科学   1244篇
基础医学   5350篇
口腔科学   870篇
临床医学   4609篇
内科学   11043篇
皮肤病学   748篇
神经病学   4230篇
特种医学   1794篇
外国民族医学   6篇
外科学   6385篇
综合类   2874篇
现状与发展   2篇
一般理论   1篇
预防医学   2613篇
眼科学   645篇
药学   4415篇
  22篇
中国医学   1310篇
肿瘤学   3858篇
  2023年   449篇
  2022年   1145篇
  2021年   1861篇
  2020年   1241篇
  2019年   1217篇
  2018年   1357篇
  2017年   1198篇
  2016年   1163篇
  2015年   1548篇
  2014年   2039篇
  2013年   2396篇
  2012年   3122篇
  2011年   3131篇
  2010年   1987篇
  2009年   1771篇
  2008年   2595篇
  2007年   2665篇
  2006年   2468篇
  2005年   2274篇
  2004年   2045篇
  2003年   1777篇
  2002年   1617篇
  2001年   1468篇
  2000年   1390篇
  1999年   1301篇
  1998年   469篇
  1997年   356篇
  1996年   374篇
  1995年   287篇
  1994年   260篇
  1993年   221篇
  1992年   674篇
  1991年   574篇
  1990年   542篇
  1989年   549篇
  1988年   456篇
  1987年   418篇
  1986年   400篇
  1985年   315篇
  1984年   259篇
  1983年   210篇
  1982年   116篇
  1979年   212篇
  1978年   128篇
  1977年   110篇
  1974年   122篇
  1973年   125篇
  1972年   122篇
  1971年   110篇
  1969年   102篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
991.
取样胶囊主要是吸取人体消化道内的消化液进行研究,本文以胃液为例,对取样胶囊吸取消化液进行探讨,分析在取样胶囊的研究中选取何种吸附材料最合适.首先对胃液成分进行分析,然后配置模拟胃液,选取六种不同吸附材料进行了吸附实验,并按实验结果绘制了不同的吸附曲线.由实验结果,对各种材料的吸附量、吸附稳定性和可靠性等进行了对比分析,同时还对取样机构模型设计的简单化因素进行分析.最后得出结论,认为德制胶棉在各个因素上都有明显的优势,适宜作为取样胶囊中的吸附材料.  相似文献   
992.
A 59-year-old woman with systemic lupus erythematosus was found to have marked hyperglycemia, extreme insulin resistance and abnormally high plasma immunoreactive insulin. Her circulating erythrocytes displayed a dramatic decrease of 125I-labeled insulin binding. Both the whole serum and purified IgG fraction strongly inhibited the binding of radiolabeled insulin to control erythrocytes. These results suggested, although indirectly, the existence of antibodies to insulin receptors in the serum of the patient. To directly investigate this issue, we used an enzyme-linked solid-phase immunoassay which allows the detection and enumeration of lymphocytes secreting antibodies towards insulin receptors. Peroxidase-conjugated anti-human immunoglobulin is used to reveal the binding of antibodies to insulin receptor-coated dishes. We demonstrated that the patient's mononuclear cells, when briefly incubated in Petri dishes with partially purified insulin receptor, were able to secrete immunoglobulins of G class specifically directed to the antigen. Moreover, only a fraction of the whole population of anti-insulin receptor antibodies was directed towards the insulin binding region of the receptor, seemingly corresponding to the auto-antibodies detected with conventional binding-inhibition assay.  相似文献   
993.
994.
OBJECTIVES: To test the hypothesis that vertical footlift asymmetries and low obstacle clearing distance during obstacle avoidance are characteristics of elderly people classified as high risk for falls. DESIGN: Controlled cross-sectional design with two conditions to cue selection of the foot-for-step initiation: sound cue and visual cue. SETTING: Senior independent living facilities. PARTICIPANTS: Eighteen community-dwelling elderly with a history of falling or prolonged Timed Up and Go score greater than 13.5 seconds, 16 elderly with no fall history and Timed Up & Go score of 13.5 seconds or less, and 15 younger subjects. MEASUREMENTS: Video kinematic analysis of bilateral footlift displacement and velocity using reflective markers as subjects stepped over foam obstacles scaled to a maximum tolerated height. RESULTS: High-risk elders contacted the obstacle more frequently and had significantly greater vertical footlift asymmetries adjusted for obstacle/subject height (mean+/-standard error asymmetry index for sound cue 3.25+/-0.42 cm, for visual cue 2.51+/-0.45 cm) than low-risk and younger subjects (P<.001). In low-risk elderly and younger subjects, the asymmetry index approached 0, which indicated symmetrical lower limb movements when stepping over the obstacles. CONCLUSION: High-risk elderly show a marked asymmetry in foot clearance while stepping over an obstacle, with the lag foot clearing the obstacle at a much lower distance than the lead foot. Possible mechanisms responsible for these findings (limited hip extension and deficits in executive cognitive function) are discussed.  相似文献   
995.
This randomized phase III clinical trial explored the efficacy of DaunoXome (DNX) versus Daunorubicin (DNR) in acute myeloid leukaemia (AML) patients aged >60 years. Three hundred and one AML patients were randomized to receive DNR (45 mg/m(2) days 1-3) or DNX (80 mg/m(2) days 1-3) plus cytarabine (AraC; 100 mg/m(2) days 1-7). Patients in complete remission (CR) received a course of the same drugs as consolidation and then were randomized for maintenance with AraC+ all trans retinoic acid or no further treatment. Among 153 patients in the DNR arm, 78 (51.0%) achieved CR, 55 (35.9%) were resistant and 20 (13.1%) died during induction. Among 148 patients in the DNX arm, 73 (49.3%) achieved CR, 47 (31.8%) were resistant and 28 (18.9%) died during induction. Univariate analysis showed no difference as to induction results. After CR, DNX showed a higher incidence of early deaths (12.5% vs. 2.6% at 6 months, P = 0.053) but a lower incidence of relapse beyond 6 months (59% vs. 78% at 24 months, P = 0.064), with a cross in overall survival (OS) and disease-free survival (DFS) curves and a later advantage for DNX arm after 12 months from diagnosis. DNX seems to improve OS and DFS in the long-term follow-up, because of a reduction in late relapses.  相似文献   
996.
997.
998.
The prevalence of gastroesophageal reflux disease (GERD) increases with age and elderly are more likely to develop severe disease. Older patients often complain of less severe or frequent heartburn than younger patients and they may present with atypical symptoms such as dysphagia, weight loss, or extraesophageal symptoms. Proton pump inhibitors (PPIs) are central in the management of GERD and are unchallenged with regards to their efficacy. They are considered safe and more effective than histamine receptor antagonists for healing esophagitis and for preventing its recurrence using a long term maintenance treatment. PPI have minimal side effects and few slight drug interactions and are considered safe for long term treatment. Pantoprazole is significantly effective both for acute and long-term treatment with excellent control of relapse and symptoms. It is well tolerated even for long-term therapy and its tolerability is optimal. Pantoprazole shows to have minimal interactions with other drugs because of a lower affinity for cytocrome P450 than older PPIs. Although the majority of elderly has concomitant illnesses and receive other drugs, this does not adversely effect the efficacy of pantoprazole because of its pharmacokinetics, which are independent of patient age. Clinical practice suggests that a low dose maintenance of PPIs should be used in older patients with GERD.  相似文献   
999.
Long-term immunoprophylaxis with anti-HBs immunoglobulins (HBIg) is used to prevent hepatitis B (HBV) reinfection after liver transplantation for HBV-related cirrhosis. This approach is highly expensive. A recent report proposed posttransplant HBV vaccination with a reinforced schedule as an alternative strategy to allow HBIg discontinuation. We investigated the efficacy of a reinforced triple course of HBV vaccination in 17 patients transplanted for HBsAg-positive cirrhosis 2 to 7 years earlier. The first cycle consisted of 3 double intramuscular doses (40 microg) of recombinant vaccine at month 0, 1, and 2, respectively. This was followed, in nonresponders, by a second cycle of 6 intradermal 10 microg doses every 15 days. All nonresponders then received a third cycle identical to the first one. Vaccination started 4.5 months after HBIg discontinuation, and lamivudine (100 mg/day) was given throughout the study. All patients were seronegative for HBsAg and HBV-DNA (by PCR) and positive for anti-HBe, and 7 were positive for anti-HDV. After the first cycle one patient (#5, 53 years old, male) developed an anti-HBs titer of 154 IU/L, another (#12) reached a titer of 20 IU/L and the remainder had titers <10 IU/L. At month 7, patient #5 reached a titer of 687 IU/L. After the second cycle only one additional patient (#9) had a slight response (an anti-HBs titer of 37 IU/L). After the third cycle patient #9 rose to an anti-HBs titer of 280 IU/L, patient #12 dropped to 10 IU/L, and no other patient responded. In conclusion, a highly reinforced HBV vaccination program is effective only in a few patients who had liver transplants for HBV-related cirrhosis.  相似文献   
1000.
De Felice C  Toti P  Di Maggio G  Parrini S  Bagnoli F 《Lancet》2001,357(9267):1500-1502
The diagnosis of Ehlers-Danlos syndrome is based on distinctive phenotypical characteristics such as hyperelastic skin and hypermobile joints. To date, no congenital physical markers exist for identifying patients with Ehlers-Danlos syndrome. Absence of the inferior labial (100% sensitivity; 99.4% specificity) and lingual frenulum (71.4% sensitivity; 100% specificity) was found to be associated with classical and hypermobility types of Ehlers-Danlos syndrome.  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