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   76241篇
  免费   7386篇
  国内免费   5695篇
耳鼻咽喉   559篇
儿科学   861篇
妇产科学   584篇
基础医学   7754篇
口腔科学   1260篇
临床医学   9507篇
内科学   10124篇
皮肤病学   620篇
神经病学   3719篇
特种医学   3240篇
外国民族医学   39篇
外科学   8155篇
综合类   15676篇
现状与发展   14篇
一般理论   16篇
预防医学   6102篇
眼科学   1561篇
药学   8475篇
  82篇
中国医学   5040篇
肿瘤学   5934篇
  2024年   287篇
  2023年   1090篇
  2022年   2812篇
  2021年   3484篇
  2020年   2856篇
  2019年   2246篇
  2018年   2415篇
  2017年   2349篇
  2016年   2130篇
  2015年   3517篇
  2014年   4378篇
  2013年   4366篇
  2012年   6406篇
  2011年   7138篇
  2010年   5027篇
  2009年   4238篇
  2008年   4693篇
  2007年   4636篇
  2006年   4366篇
  2005年   3965篇
  2004年   2783篇
  2003年   2463篇
  2002年   2108篇
  2001年   1635篇
  2000年   1462篇
  1999年   1156篇
  1998年   808篇
  1997年   787篇
  1996年   618篇
  1995年   551篇
  1994年   408篇
  1993年   316篇
  1992年   258篇
  1991年   211篇
  1990年   202篇
  1989年   205篇
  1988年   165篇
  1987年   171篇
  1986年   123篇
  1985年   111篇
  1984年   57篇
  1983年   45篇
  1982年   42篇
  1981年   44篇
  1980年   32篇
  1979年   25篇
  1978年   13篇
  1977年   12篇
  1976年   25篇
  1975年   11篇
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
31.
张萍  凌奋  曾嫣 《上海医学》2004,27(10):736-738
目的 比较评估腹腔镜辅助阴道子宫切除术与经腹子宫切除术两种手术的临床效果。方法  12 0例妇科良性疾病患者需行子宫切除术 ,但有经阴道子宫切除术的相对禁忌证、子宫不超过孕 16周 ,随机分成两组 ,甲组 (6 0例 )行腹腔镜辅助阴式子宫切除术 ,乙组 (6 0例 )行经腹子宫切除术。结果 两组患者年龄、产次、术前血红蛋白水平、子宫平均重量、术中失血、手术时间的差异无显著性 (P >0 .0 5 )。甲组术后疼痛程度、术后住院时间明显少于乙组 (P <0 .0 1) ,两组均未出现严重手术并发症。结论 腹腔镜辅助阴式子宫切除术具有创伤小、恢复快、住院时间短等优点 ,妇科医师经过良好的腹腔镜手术操作技能培训 ,能对大部分原不宜行阴式子宫切除术而需行经腹子宫切除术的患者行腹腔镜辅助阴式子宫切除术。  相似文献   
32.
33.
Mantle cell lymphoma is non-Hodgkin's B-cell lymphoma characterized by the t(11;14)(q13;q32) translocation. Peripheral blood involvement of mantle cell lymphoma is usually associated with a poor prognosis and therefore, its identification is clinically important. In this study, we performed cyclin D1/IgH-probe fusion fluorescence in situ hybridization analysis on 223 peripheral blood samples: 185 from 125 mantle cell lymphoma patients, and 38 normal controls. The cutoff values for the test were established using normal controls. Flow cytometry on peripheral blood and corresponding bone marrow samples was used to evaluate this test. In all, 26% of the 185 peripheral blood samples and 27% of the 161 corresponding bone marrow samples were flow cytometry positive for mantle cell lymphoma. The mean numbers of single and- double-fusion signals and the mean number of CD5/CD19-positive cells, absolute blood lymphocyte count, and white blood cell count were significantly higher in peripheral blood and corresponding bone marrow samples with mantle cell lymphoma-positive flow cytometry. Double-fusion signals were more specific than single-fusion ones. Fluorescence in situ hybridization was far more likely to be positive for mantle cell lymphoma when the peripheral blood and the corresponding bone marrow samples had positive flow cytometry results or morphology (P<0.01). Our study indicates that cyclin D1/IgH-fusion fluorescence in situ hybridization analysis could be used to determine the presence and character of circulating mantle cell lymphoma cells in peripheral blood, thus enhancing our ability to evaluate leukemic mantle cell lymphoma and minimum residual disease.  相似文献   
34.
目的探讨外源性Nurrl基因修饰的人脐血间充质干细胞在基因重组成纤维细胞生长因子-8(FGF8)和音猬因子(Shh)诱导下体外分化为多巴胺能神经元的情况。方法间充质干细胞被随机分为A组(对照组)、B组(Nurrl组)、C组(FGF8+Shh组)及D组(Nurrl+FGF8+Shh),采用脂质体法将pcDNA3.1-Ntrr1转染B、D组间充质干细胞,Western blot观察Nurr1基因表达情况,并在神经元条件培养液中进行增殖培养和诱导分化,间接免疫荧光染色法鉴定细胞性质,高效液相色谱法测定多巴胺含量。结果Western blot结果显示转染后Nurr1蛋白表达明显增高。A组和B组未发现酪氨酸羟化酶(TH)阳性细胞,而C组和D组TH阳性细胞分别为10.12%±2.65%及25.36%±3.13%,多巴胺含量分别为(43.6±2.1)nmol/L及(83.2±3.5)nmol/L,差异均有显著性意义(P< 0.01)。结论人脐血间充质干细胞在FGF8和Shh诱导下可以分化为多巴胺能神经元,外源性Nurr1基因修饰后,分化为多巴胺能神经元的数量增加。  相似文献   
35.
36.
Two embryonal CNS tumors, atypical teratoid/rabdoid tumor (AT/RT) and primitive neuroectodermal tumor (PNET), may be confused with each other and misdiagnosed. Here we report an infant with a congenital supratentorial tumor, which was detected by fetal MRI at 37 weeks gestation. On routine histological examination, the tumor was composed mainly of small undifferentiated cells, among which many rhabdoid cells and occasional sickle‐shaped embracing cells were observed. No mesenchymal or epithelial areas were evident. Our impression was that the tumor was an atypical example of AT/RT. Immunohistochemically, almost all the tumor cells were strongly positive for vimentin. However, epithelial membrane antigen was notably negative, and most of the tumor cell nuclei were clearly positive for INI1. In addition, many tumor cells were positive for neurofilament protein. There were also occasional small areas containing many tumor cells positive for glial fibrillary acidic protein. Finally, a diagnosis of PNET, with a rhabdoid phenotype and expression of neuronal and glial markers, was made. In the present case, application of INI1 immunostaining was very helpful for distinguishing PNET from AT/RT.  相似文献   
37.
38.
39.
BACKGROUND: Seizure frequency is in abnormal distribution, and it is not enough to express the trend of concentration using means, and its median loses a lot of information, thus it lacks of a standard for evaluating the therapeutic effects based on seizure frequency. OBJECTIVE: To establish a method for evaluating the therapeutic effects on anti-epileptic drugs using changes of interval and duration of seizure. DESIGN: A prospective cohort study. SETTING: Zhumadian Psychiatric Hospital. PARTICIPANTS: Outpatients and inpatients suffering from epilepsy attending firstly visited Zhumadian Psychiatric Hospital from June 2001 to June 2002 were enrolled. They were diagnosed as epileptic according to the International Classification of Epileptic Seizure by International League Against Epilepsy (1981) based on the clinical history, physical examination, and investigations. The interval time was no more than 6 months. Informed consent was obtained from all the subjects, and the study was approved by the hospital ethical committee. METHODS: ① For the first visit and each follow-up, the following data were recorded, including general demographic information, seizure type, the date and time of ictus, the duration of ictus, and inducement or situation related, according to which the following indexes could be calculated, including seizure styles, interval, duration, cluster frequency and cluster duration. The information from the first review was noted as annals A. The second interview was taken at the end of the evaluating period; the information from the second review was noted as annals B. The third interview was taken within two weeks after the second one; the information from the third review was noted as annals C. The annals B or the annals C were respectively compared with the annals A in the light of the same types or the same styles of the same patient. Summation of the scores of interval change and duration change of the same type or the same style and 5 of basic score was the score of a corresponding seizure type or a corresponding style of one patient. In order to test its reliability and validity, the score of change of frequency or duration plus 5 scores respectively was the score of frequency or duration. ② Reliability and validity were tested by calculating corresponding correlation coefficient with SPSS 11.0. ROC curve was used for developing diagnostic criterion of predicting therapeutic effects with SPSS 11.0. MAIN OUTCOME MEASURES: ① Reliability and validity; ② Diagnostic criterion for predicting therapeutic effects one year later. RESULTS: Totally 28 patients were involved in the final analysis of results. ① Reliability and validity were high: rinter-rater=0.98, rtest-retest=0.99, rconstruct validity=0.83. ② A total score > 6 was the optimal diagnostic criteria for predicting therapeutic effects one year later, in other words, a patient who scored more than 6 at the evaluating period may be seizure-free one year later. CONCLUSION: It is a potential tool for evaluating epileptic therapeutic outcome, and it can be diffusely used in interrelated fields after being further validated.  相似文献   
40.
OBJECTIVES: Brain edema occurs following clinical as well as experimental cardiac arrest (CA) and predicts a poor neurologic outcome. The objective of this study was to determine the expression of cerebral cortex aquaporin (AQP)-4, a member of a family of membrane water-channel proteins, in brain edema formation following normothermic or hypothermic CA. METHODS: Twenty-four rats were subjected to time-matched normothermic (N-Sham, 37.5 degrees C +/- 0.5 degrees C, n = 6) or hypothermic (H-Sham, 34 degrees C +/- 0.5 degrees C, n = 6) sham experiments and normothermic (N-CA, n = 6) or hypothermic (H-CA, n = 6) CA induced by asphyxiation for 8 minutes. Hypothermia was induced before CA. The animals were resuscitated with cardiopulmonary resuscitation, ventilation, and epinephrine administration. Brain edema was determined by brain wet-to-dry weight ratio at one hour of resuscitation. AQP4 immunoactivity in the cerebral cortex was determined using immunohistochemical staining and was semiquantified as an intensity of staining with an automated cell imaging system. RESULTS: Mild hypothermia in the sham experiments did not alter cerebral cortex AQP4 immunoactivity (mean +/- SD) (55.0 +/- 3.7 in H-Sham vs. 53.3 +/- 1.7 in N-Sham, p > 0.05). N-CA resulted in a significant increase in AQP4 immunoactivity (61.8 +/- 4.5) compared with N-Sham (p = 0.01) and H-Sham (p = 0.03). H-CA attenuated AQP4 compared with N-CA (53.4 +/- 1.3, p = 0.01). Brain wet-to-dry weight ratios were 4.41 +/- 0.07 in N-Sham, 4.40 +/- 0.08 in H-Sham (p > 0.05 vs. N-Sham), 4.55 +/- 0.04 in N-CA (p = 0.004 vs. N-Sham; p = 0.005 vs. H-Sham), and 4.43 +/- 0.09 in H-CA (p = 0.02 vs. N-CA; p > 0.05 vs. N-Sham and H-Sham). CONCLUSIONS: Cerebral cortical AQP4 expression is up-regulated after normothermic CA, which is attenuated by hypothermia induced before CA.  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