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   9362篇
  免费   860篇
  国内免费   442篇
耳鼻咽喉   86篇
儿科学   153篇
妇产科学   116篇
基础医学   1018篇
口腔科学   238篇
临床医学   1116篇
内科学   1572篇
皮肤病学   293篇
神经病学   541篇
特种医学   380篇
外国民族医学   3篇
外科学   1002篇
综合类   1247篇
现状与发展   1篇
一般理论   1篇
预防医学   632篇
眼科学   184篇
药学   944篇
  4篇
中国医学   418篇
肿瘤学   715篇
  2024年   16篇
  2023年   117篇
  2022年   266篇
  2021年   383篇
  2020年   260篇
  2019年   283篇
  2018年   325篇
  2017年   289篇
  2016年   279篇
  2015年   393篇
  2014年   452篇
  2013年   508篇
  2012年   625篇
  2011年   706篇
  2010年   451篇
  2009年   344篇
  2008年   525篇
  2007年   525篇
  2006年   531篇
  2005年   475篇
  2004年   307篇
  2003年   329篇
  2002年   242篇
  2001年   207篇
  2000年   192篇
  1999年   211篇
  1998年   158篇
  1997年   144篇
  1996年   111篇
  1995年   96篇
  1994年   76篇
  1993年   50篇
  1992年   103篇
  1991年   72篇
  1990年   75篇
  1989年   48篇
  1988年   66篇
  1987年   59篇
  1986年   50篇
  1985年   49篇
  1984年   27篇
  1983年   24篇
  1982年   21篇
  1981年   32篇
  1980年   19篇
  1979年   24篇
  1978年   10篇
  1977年   13篇
  1976年   19篇
  1973年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
黄芪多糖对糖尿病大鼠微血管病变的作用及机制的研究   总被引:17,自引:2,他引:15  
目的:探讨黄芪多糖(APS)对糖尿病大鼠微血管病变的影响以及对糖尿病的治疗作用及机制。方法:成年,健康SD大鼠40只,雌雄不限,分成四组:正常对照组,糖尿病组(腹腔注射四氧嘧啶200mg/kg),APS组(造模成功后用APS治疗),优降糖组(造模成功后用优降糖治疗)。治疗两周时测一次血糖,四周后,测血糖;颈动脉取血测定血清胰素水平,NO和MDA含量。应用形态定量的方法比较各组的心肌病理变化。结果:腹腔注射alloxan(200mg/kg)后的SD大鼠血糖浓度显升高,血清NO,MDA,胰岛素水平明显改变。APS治疗四周后,血糖浓度明显下降,与优降糖治疗组无明显差异,血清NO较未治疗组明显升高(P<0.01),血清MDA较未治疗组明显减少(P<0.01),血清胰岛素水平升高(P<0.05),光镜下观察,糖尿病大鼠的心肌毛细血管数量减少,基底膜增厚,微血管与心肌纤维的比率显减低,这些改变都可被APS改善.结论:APS有降低血糖和保护血管内皮细胞的作用,这可能与APS减轻氧自由基的损伤,影响NO的产生以及促进胰岛B细胞的损伤的恢复有关。  相似文献   
72.
采用化学共沉淀法制备锑掺杂二氧化锡(ATO)超细导电粉体,研究了反应温度,滴定终点pH值,掺锑量及锻炼温度对粉体导电性的影响,并对实验结果进行了讨论。  相似文献   
73.
探讨了以H2SO4和CH2OHCH2Cl为酸解介质时,氯化法金红石型钛白粉表面包铝的行为及形态特征。利用正交实验研究了包膜过程中,熟化pH、熟化时间以及温度对包铝钛白粉白度的影响。氯化法金红石型钛白粉浆在pH为10时,Zeta电位最大,在水中达到最佳分散,利用H2OHCH2Cl作为酸解介质时,浆液中的均相成核得到显著抑制,钛白粉表面的包膜质量得到明显改善。以稀硫酸作为酸解介质时,随熟化温度升高和熟化时间的延长,钛白粉包覆效果明显改善,白度值明显升高。  相似文献   
74.
HEALTH CARE REPORT CARDS INVOLVE COMPARISONS of health care systems, hospitals or clinicians on performance measures. They are going to be an important feature of medical care in Canada in the new millennium as patients demand more information about their medical care. Although many clinicians are aware of this growing trend, they may not be prepared for all of its implications. In this article, we provide some historical background on health care report cards and describe a number of strategies to help clinicians survive and thrive in the report card era. We offer a number of tips ranging from knowing your outcomes first to proactively getting involved in developing report cards.  相似文献   
75.
尿液结合性胆红素的纯化   总被引:2,自引:1,他引:1  
Y Guo  M Chen  Y Tu  H Luo  S Li  D Yan  M Niu 《华西医科大学学报》2001,32(4):579-581
OBJECTIVES: To develop a simple, practical method with fine yield and purity for separating conjugated bilirubin(Bc) from a sustainable and facile material in order that it could serve as a calibrator for total and direct bilirubin determination. METHODS: Isolating Bc from urine of patients with obstructive jaundice by CHCl3: CH3CH2OH(1:1, V/V) followed by CNBr activated Sepharose 4B-HAS affinity chromatography, we analyzed the products by the use of Doumas J-G diazo method and HPLC, respectively. RESULTS: Determined by J-G diazo method, the crude product extracted by CHCl3: CH3CH2OH(1:1, V/V) yields 90.2 +/- 5.4%(n = 3) of urine Bc, the ratio of Bc to total dry weight being 67.9 +/- 6.4%(n = 3). The final product purified by affinity chromatography with the ratio of separation of 1.5, 1.737 and analyzed by HPLC has the yield of 46.9% and purity of 94.7%(BDG of 76.2%, BMG of 18.5%). CONCLUSION: The above data demonstrate that urine conjugated bilirubin can be successfully purified by CHCl3: CH3CH2OH extraction followed by Sephrose-HSA affinity chromatography with sufficient purity and output.  相似文献   
76.
目的 探索一种来源方便 ,具有延续性 ,利于胆红素测定校准物或质控物制备 ,且方法简便、实用、产率和纯度可靠的结合性胆红素 (Bc)纯化方法。方法 应用 CHCl3 ∶ CH3 CH2 OH(1∶ 1,V/V)萃取与 CNBractivated Sepharose4B- HSA亲和层析相结合的方法对胆道梗阻性高胆红素尿液进行分离纯化 ,并以 Doum as J- G法和 HPL C分析产品。结果 由 CHCl3 ∶ CH3 CH2 OH(1∶ 1,V/V)萃取所得的粗纯品经 J- G法检测产率为 90 .2±5 .4% (n=3) ,胆红素含量占总干重的 6 7.9± 6 .4% (n=3)。亲和层析的洗脱峰间的分离度为 1.5、1.737。层析后再萃取所得精纯品经 HPL C分析 ,产率为 46 .9% ,纯度 94.7% ,其中 BDG76 .2 % ,BMG18.5 %。结论 采用有机物萃取和 CNBr activated Sepharose4B- HSA亲和层析相结合的方法纯化结合性胆红素 (BMG& BDG)具有很好的可靠性和可行性  相似文献   
77.
BackgroundFamily history of prostate cancer (PCa) is a well-known risk factor, and both common and rare genetic variants are associated with the disease.ObjectiveTo detect new genetic variants associated with PCa, capitalizing on the role of family history and more aggressive PCa.Design, setting, and participantsA two-stage design was used. In stage one, whole-exome sequencing was used to identify potential risk alleles among affected men with a strong family history of disease or with more aggressive disease (491 cases and 429 controls). Aggressive disease was based on a sum of scores for Gleason score, node status, metastasis, tumor stage, prostate-specific antigen at diagnosis, systemic recurrence, and time to PCa death. Genes identified in stage one were screened in stage two using a custom-capture design in an independent set of 2917 cases and 1899 controls.Outcome measurements and statistical analysisFrequencies of genetic variants (singly or jointly in a gene) were compared between cases and controls.Results and limitationsEleven genes previously reported to be associated with PCa were detected (ATM, BRCA2, HOXB13, FAM111A, EMSY, HNF1B, KLK3, MSMB, PCAT1, PRSS3, and TERT), as well as an additional 10 novel genes (PABPC1, QK1, FAM114A1, MUC6, MYCBP2, RAPGEF4, RNASEH2B, ULK4, XPO7, and THAP3). Of these 10 novel genes, all but PABPC1 and ULK4 were primarily associated with the risk of aggressive PCa.ConclusionsOur approach demonstrates the advantage of gene sequencing in the search for genetic variants associated with PCa and the benefits of sampling patients with a strong family history of disease or an aggressive form of disease.Patient summaryMultiple genes are associated with prostate cancer (PCa) among men with a strong family history of this disease or among men with an aggressive form of PCa.  相似文献   
78.
BackgroundDuctal prostate adenocarcinoma (DAC) is a rare, aggressive, histologic variant of prostate cancer that is treated with conventional therapies, similar to high-risk prostate adenocarcinoma (PAC).ObjectiveTo assess the outcomes of men undergoing definitive therapy for DAC or high-risk PAC and to explore the effects of androgen deprivation therapy (ADT) in improving the outcomes of DAC.Design, setting, and participantsA single-center retrospective review of all patients with cT1–4/N0–1 DAC from 2005 to 2018 was performed. Those undergoing radical prostatectomy (RP) or radiotherapy (RTx) for DAC were compared with cohorts of high-risk PAC patients.Outcome measurements and statistical analysisMetastasis-free survival (MFS) and overall survival (OS) rates were analyzed using Kaplan-Meier and Cox regression models.Results and limitationsA total of 228 men with DAC were identified; 163 underwent RP, 34 underwent RTx, and 31 had neoadjuvant therapy prior to RP. In this study, 163 DAC patients and 155 PAC patients undergoing RP were compared. Similarly, 34 DAC patients and 74 PAC patients undergoing RTx were compared. DAC patients undergoing RP or RTx had worse 5-yr MFS (75% vs 95% and 62% vs 93%, respectively, p < 0.001) and 5-yr OS (88% vs 97% and 82% vs 100%, respectively, p < 0.05) compared with PAC patients. In the 76 men who received adjuvant/salvage ADT after RP, DAC also had worse MFS and OS than PAC (p < 0.01). A genomic analysis revealed that 10/11 (91%) DACs treated with ADT had intrinsic upregulation of androgen-resistant pathways. Further, none of the DAC patients (0/15) who received only neoadjuvant ADT prior to RP had any pathologic downgrading. The retrospective nature was a limitation.ConclusionsMen undergoing RP or RTx for DAC had worse outcomes than PAC patients, regardless of the treatment modality. Upregulation of several intrinsic resistance pathways in DAC rendered ADT less effective. Further evaluation of the underlying biology of DAC with clinical trials is needed.Patient summaryThis study demonstrated worse outcomes among patients with ductal adenocarcinoma of the prostate than among high-grade prostate adenocarcinoma patients, regardless of the treatment modality.  相似文献   
79.
Chen  Hongli  Tu  Mengru  Shi  Jia  Wang  Yunhao  Hou  Zhenhao  Wang  Jinhai 《Lasers in medical science》2021,36(3):555-562
Lasers in Medical Science - Delayed wound healing is one of the most challenging complications of diabetes mellitus (DM) in clinical medicine, and it is related to the excessive generation of...  相似文献   
80.
李嫒  涂素华 《护理学杂志》2021,36(10):107-109
阐述婴儿生物养育的概念、实施步骤、与传统哺乳姿势的区别、对母婴的影响,以期提高我国医务工作者对生物养育的认知、促进生物养育提供参考.  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