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   13717篇
  免费   1227篇
  国内免费   22篇
耳鼻咽喉   123篇
儿科学   358篇
妇产科学   276篇
基础医学   1948篇
口腔科学   367篇
临床医学   1544篇
内科学   2871篇
皮肤病学   218篇
神经病学   1152篇
特种医学   323篇
外科学   1747篇
综合类   259篇
一般理论   9篇
预防医学   1549篇
眼科学   283篇
药学   1031篇
中国医学   33篇
肿瘤学   875篇
  2023年   122篇
  2022年   177篇
  2021年   357篇
  2020年   221篇
  2019年   317篇
  2018年   350篇
  2017年   287篇
  2016年   262篇
  2015年   334篇
  2014年   361篇
  2013年   575篇
  2012年   862篇
  2011年   851篇
  2010年   524篇
  2009年   443篇
  2008年   696篇
  2007年   698篇
  2006年   686篇
  2005年   706篇
  2004年   595篇
  2003年   592篇
  2002年   529篇
  2001年   276篇
  2000年   300篇
  1999年   266篇
  1998年   124篇
  1997年   118篇
  1996年   112篇
  1995年   114篇
  1994年   114篇
  1993年   98篇
  1992年   200篇
  1991年   184篇
  1990年   167篇
  1989年   170篇
  1988年   165篇
  1987年   160篇
  1986年   145篇
  1985年   160篇
  1984年   118篇
  1983年   108篇
  1982年   76篇
  1981年   72篇
  1980年   63篇
  1979年   114篇
  1978年   69篇
  1977年   74篇
  1973年   89篇
  1972年   75篇
  1971年   75篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Summary Cytosine arabinsodie (ara-C) and etoposide (VP-16) display synergy in the laboratory. Twenty-six patients participated in a phase I study of high-dose ara-C in combination with VP-16. The dose of VP-16 was held constant at 50 mg/m2 as an intermittent infusion over 33 h; escalating doses of ara-C were given as infusions during hours 9–12 and 21–24. Myelosuppression was the dose-limiting toxicity and occurred with doses considerably less than those expected from studies of the two drugs as single agents. The suggested initial doses for phase II trials with this schedule are 750 mg/m2×2 doses of ara-C and 50 mg/m2 of VP-16. Nonhematologic toxicity was minimal; therefore, further dose escalation is feasible in patients in whom myelosuppression is acceptable.Supported in part by grants from the National Cancer Institute (CA-12197 and CA-09422) and the American Cancer Society CF-85-182  相似文献   
6.
Power spectral and discriminant analysis techniques were used to compare EEG records obtained at term and at 3 months past term from 5 groups of varying risk and developmental outcome. The groups were: healthy full-terms; healthy pre-terms with normal outcomes; sick pre-terms with normal outcomes; sick pre-terms with delayed development; sick pre-terms with later neurological problems. The EEG samples recorded at term were identified as belonging to the correct subject group at 52-70% accuracy, 20% being chance for 5 groups. The accuracy varied with the 4 classes of EEG patterns used. The individual subjects were also classified into their correct groups with few exceptions. Similar success was obtained with EEG samples selected from recording at 3 months past term. The predominant power spectral discriminating features were changes in intra- and inter-hemispheric coherence, and increased power, particularly in the middle and higher frequency range. Thus, computer analyses of EEG samples, using features not readily identified visually, differentiated risk from non-risk infants and also differentiated infants with substantial neonatal medical complications who have good or poor developmental outcomes.  相似文献   
7.
Hypoxia is related to poor prognosis because it is associated to chemo-and radioresistance. During recent years the evolution of imaging methods like PET/CT and MRI has meant the appearance of new perspectives with direct implications in radiation therapy. We discuss previous experiences in staging, planning and in the follow-up process with these techniques for measuring tumour hypoxia.  相似文献   
8.
Coccidiosis of chickens, caused by species of Eimeria (Protozoa, Apicomplexa), is an intestinal disease of major economic importance worldwide. In the present study, the reproductive characteristics of a precocious line (designated E. tenella Rt3+15) from Australia were investigated in chicken embryos and the implications of the findings briefly discussed.  相似文献   
9.
Nuclear magnetic resonance (NMR) spectroscopy has been reported as an alternative method for quantitating deuterium oxide concentrations in the evaluation of total-body-water in humans. However, the presence of dissolved plasma proteins results in an underestimation of deuterium NMR (2H-NMR) intensity ratios, thereby causing an overestimation (5-6%) of total-body-water (TBW) values determined from nonsublimed patient plasma samples. We demonstrate that plasma samples must be corrected for the volume percentage of water in plasma. Correction of initial 2H-NMR intensity ratios with a factor of 0.93 results in intensity ratios comparable to those determined from plasma samples subjected to vacuum sublimation to remove all plasma solutes.  相似文献   
10.
The Medical Research Council UKALL V trial for children with standard-risk acute lymphoblastic leukemia (ALL) (aged 1 to 14 years, leucocyte count less than 20 X 10(9)/L) was designed to determine whether the immunosuppressive effects of treatment could be reduced without sacrifice of antileukemic effect by alterations in the type of continuing therapy or in fractionation of cranial irradiation. Remission was achieved in 496 children on standard induction therapy, and 309 children received 24 Gy of cranial irradiation in ten to 16 fractions over 21 days, and 174 received 21 Gy in five to nine fractions over 21 days. The type of radiotherapy administered had no influence on relapse at any site or rate of death in remission. All 496 children were randomized to receive chemotherapy for 2 or 3 years with 6-mercaptopurine and methotrexate either as a continuous (group C) or a semicontinuous (group G) regimen or as a five-day pulse every 3 weeks (group I). All groups also received vincristine and prednisolone every 6 weeks. With a minimum follow-up of almost 7 years, patients in group I had significantly fewer remission deaths (P = .025) but a much higher rate of bone marrow relapse than those in group C or G (P = .002). There was an overall benefit for 3 years of chemotherapy compared with 2 years, which in contrast to previous studies, was more apparent in girls and in patients in groups C and G. Testicular relapse occurred in 37 boys, including 19 patients off therapy, with a previously negative biopsy. The overall results confirmed the prognostic significance of initial leucocyte count, even among these standard-risk patients, while girls had a superior rate of disease-free survival, but not of hematologic remission. It is concluded that, even among standard-risk patients, the prognosis is influenced by the height of the initial leukocyte count. While alterations in the fractionation of cranial irradiation do not appear to have influenced disease-free survival, intermittent continuing chemotherapy, although less immunosuppressive, is less effective than conventional continuous therapy in the treatment of ALL. In this study, 3 years of chemotherapy appeared superior to 2 years.  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