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   44129篇
  免费   2219篇
  国内免费   150篇
耳鼻咽喉   630篇
儿科学   1773篇
妇产科学   723篇
基础医学   5834篇
口腔科学   1011篇
临床医学   2871篇
内科学   10927篇
皮肤病学   1545篇
神经病学   3554篇
特种医学   1332篇
外科学   6007篇
综合类   307篇
一般理论   17篇
预防医学   3795篇
眼科学   1185篇
药学   2596篇
中国医学   200篇
肿瘤学   2191篇
  2024年   40篇
  2023年   298篇
  2022年   301篇
  2021年   1182篇
  2020年   543篇
  2019年   1246篇
  2018年   1937篇
  2017年   1114篇
  2016年   939篇
  2015年   835篇
  2014年   1035篇
  2013年   1787篇
  2012年   3158篇
  2011年   3505篇
  2010年   1737篇
  2009年   1077篇
  2008年   2741篇
  2007年   2845篇
  2006年   2573篇
  2005年   2673篇
  2004年   2454篇
  2003年   2404篇
  2002年   2169篇
  2001年   1579篇
  2000年   2002篇
  1999年   1128篇
  1998年   354篇
  1997年   240篇
  1996年   221篇
  1995年   219篇
  1994年   162篇
  1993年   149篇
  1992年   181篇
  1991年   168篇
  1990年   128篇
  1989年   151篇
  1988年   131篇
  1987年   120篇
  1986年   120篇
  1985年   124篇
  1984年   93篇
  1983年   71篇
  1982年   68篇
  1981年   44篇
  1980年   57篇
  1979年   35篇
  1978年   35篇
  1977年   47篇
  1976年   40篇
  1975年   37篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
23.
BACKGROUND: There are numerous studies that individually evaluate the efficacy/effectiveness and toxicity of drugs in the systemic treatment of psoriasis. On the contrary, we can hardly find studies that compare each other. OBJECTIVE: To evaluate and compare the effectiveness and toxicity of mycophenolate mofetil and cyclosporin in chronic plaque psoriasis through a prospective, sequential, cross-over, non-randomized, two-phase, open-label study. PATIENTS/METHODS: Eight patients (five women and three men; mean age 57, range 35-78) with moderate-to-severe chronic plaque psoriasis were included in the study. They were treated with oral mycophenolate mofetil (30 mg/kg/day) over a period of 16 weeks. Following a variable washout period and after a new outbreak of the disease, oral cyclosporin was introduced at a dose of 4 mg/kg/day. During both treatment regimens, follow-up visits were performed at 3, 8 and 16 weeks. RESULTS: In both groups, the PASI started to decrease once treatment was begun. Cyclosporin was faster and statistically a lot more effective than mycophenolate mofetil, reaching a higher number of complete remissions and better percentages of PASI improvement from baseline (45.7%, 60.2% and 60.5% at 3, 8 and 16 weeks respectively for mycophenolate mofetil, and 89.7%, 95.3% and 95.3% respectively at the same intervals for cyclosporin). Cyclosporin was also more predictable in its action as the percentage of improvement along the follow-up visits had a much wider range for mycophenolate mofetil. Overall, the tolerability of both drugs was good. None of the patients had to discontinue treatment because of an adverse event. Two patients treated with cyclosporin showed increased plasma levels of creatinine. CONCLUSIONS: Cyclosporin is more effective, fast, and predictable in its effect than mycophenolate mofetil to control moderate-to-severe chronic plaque psoriasis. Both drugs are well tolerated in short courses of treatment.  相似文献   
24.
Objective The purpose of this study is to analyze clinical aspects and disease-free survival (DFS) in children less than 3 years of age diagnosed with low-grade astrocytoma. Methods In a period of 24 years (1980–2004), a total of 43 (5.4%) children were registered with these characteristics. Twenty-three patients had pilocytic astrocytoma, 18 diffused, and 2 mixed. Thirty-one (72.1%) children had incomplete surgical tumor resection and 12 (27.9%) had a complete tumor resection. Twelve (27.9%) patients had cranial radiotherapy and 17 (39.5%) received chemotherapy. Overall survival was recorded in 23 (53%). DFS was 50% at 250 months of follow-up for the whole group. DFS for the supratentorial group was 60% at 250 months, whereas, for the infratentorial, it was 22% at 120 months (p = 0.008). Conclusion The only favorable prognostic pattern was the supratentorial presentation. Radiotherapy and chemotherapy did not alter the outcome.  相似文献   
25.
A precise and simple method for the determination of (234)Th activity by Cerenkov counting is described. A calibrated natural uranium solution (having (234m)Pa and (238)U in secular equilibrium) in 0.1M HNO(3) is used to construct the calibration curve. Because (231)Th (a beta-emitting nuclide present in the decay chain of (235)U) contribution to Cerenkov counting is experimentally proved to be negligible only in the case of low enriched uranium samples, simple calculations are needed to accomplish the activity determination.  相似文献   
26.
Ganciclovir (GCV) prophylaxis or pre-emptive therapy significantly reduce the rate of cytomegalovirus (CMV) disease and viremia, but increase the potential for emergence of ganciclovir-resistant CMV strains. The inhibitor concentration at 50% (IC(50)) of GCV from 156 CMV isolates from 59 renal or heart transplant recipients was calculated by means of a rapid phenotypic susceptibility assay. Twenty-seven strains were from 14 patients undergoing GCV therapy. The IC(50) was higher in patients under the prophylaxis regimen. One CMV strain, from a heart transplant recipient, became GCV-resistant after 1 month of therapy (IC(50)=13.7 micromol/l). These data, together with clinical and virological markers, suggested that a switch to foscarnet was necessary, and good evolution was observed. Thus, assay of CMV susceptibility to GCV could be helpful in clinical management.  相似文献   
27.
A case of islet cell tumor occurring in a patient with the multiple endocrine neoplasia type I syndrome is reported. Immunostaining for insulin was strongly positive in the tumor cells. Numerous dense-core granules of endocrine caliber were identified ultrastructurally. Morphometric analysis of the secretory granules in 20 islet cell tumors gave a granule size of 182 +/- 52 nm (mean +/- standard deviation).  相似文献   
28.
29.
A 7-cm anterior mediastinal tumor in an 80-year-old woman was found by light and electron microscopy to be a neuroblastoma. Immunoreactivity for neuron-specific enolase, synaptophysin, and chromogranin supported the diagnosis. Neuroblastoma is an uncommon tumor in adults and we are not aware of a previous report of such a tumor in a patient of this age.  相似文献   
30.
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