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   2525篇
  免费   126篇
  国内免费   30篇
耳鼻咽喉   28篇
儿科学   85篇
妇产科学   14篇
基础医学   224篇
口腔科学   33篇
临床医学   478篇
内科学   400篇
皮肤病学   15篇
神经病学   487篇
特种医学   135篇
外科学   370篇
综合类   49篇
预防医学   91篇
眼科学   17篇
药学   107篇
中国医学   8篇
肿瘤学   140篇
  2022年   13篇
  2021年   30篇
  2020年   22篇
  2019年   24篇
  2018年   36篇
  2017年   58篇
  2016年   55篇
  2015年   72篇
  2014年   78篇
  2013年   105篇
  2012年   126篇
  2011年   137篇
  2010年   88篇
  2009年   91篇
  2008年   137篇
  2007年   131篇
  2006年   114篇
  2005年   129篇
  2004年   100篇
  2003年   84篇
  2002年   83篇
  2001年   89篇
  2000年   73篇
  1999年   57篇
  1998年   38篇
  1997年   33篇
  1996年   32篇
  1995年   15篇
  1994年   24篇
  1993年   22篇
  1992年   53篇
  1991年   40篇
  1990年   37篇
  1989年   46篇
  1988年   46篇
  1987年   36篇
  1986年   31篇
  1985年   28篇
  1984年   25篇
  1983年   21篇
  1982年   15篇
  1981年   13篇
  1980年   15篇
  1979年   15篇
  1978年   13篇
  1977年   12篇
  1974年   12篇
  1973年   10篇
  1968年   10篇
  1965年   12篇
排序方式: 共有2681条查询结果,搜索用时 15 毫秒
41.
PURPOSE: We determined the maximum-tolerated dose (MTD) and the dose-limiting toxicities (DLT) of 17-allylamino-17-demethoxygeldanamycin (17-AAG) when infused on days 1, 8, and 15 of a 28-day cycle in advanced solid tumor patients. We also characterized the pharmacokinetics of 17-AAG, its effect on chaperone and client proteins, and whether cytochrome P450 (CYP) 3A5 and NAD(P)H:quinone oxidoreductase 1 (NQO1) polymorphisms affected 17-AAG disposition or toxicity. PATIENTS AND METHODS: An accelerated titration design was used. Biomarkers were measured in peripheral-blood mononuclear cells (PBMCs) at baseline and on days 1 and 15, and pharmacokinetic analysis was performed on day 1 of cycle 1. CYP3A5*3 and NQO1*2 genotypes were determined and correlated with pharmacokinetics and toxicity. RESULTS: Twenty-one patients received 52 courses at 11 dose levels. DLTs at 431 mg/m(2) were grade 3 bilirubin (n = 1), AST (n = 1), anemia (n = 1), nausea (n = 1), vomiting (n = 1), and myalgias (n = 1). No tumor responses were seen. 17-AAG consistently increased heat shock protein (Hsp) 70 levels in PBMCs. At the MTD, the clearance and half-life (t(1/2)) of 17-AAG were 11.6 L/h/m(2) and 4.15 hours, respectively; whereas the active metabolite 17-aminogeldanamycin had a t(1/2) of 7.63 hours. The CYP3A5*3 and NQO1*2 polymorphisms were not associated with 17-AAG toxicity. The CYP3A5*3 polymorphism was associated with higher 17-AAG clearance. CONCLUSION: The MTD of weekly 17-AAG is 308 mg/m(2). 17-AAG induced Hsp70 in PBMCs, indicating that Hsp90 has been affected. Further evaluation of 17-AAG is ongoing using a twice-weekly regimen, and this schedule of 17-AAG is being tested in combination with chemotherapy.  相似文献   
42.
范尚坦  苏中武  李承祜 《药学学报》1988,23(12):944-952
本文对模式产地的山药Piper haneei Maxim, var, hancei Maxim,和腺鳞蒟P. kancei Maxim var. squamiglanduferum Fan var. nov.进行了原植物形态特征和花序轴、花序梗、茎、叶的显微特征以及化学成分的TLC及UV比较。挥发油的GC—MS研究共鉴定出38个成分,其中28个是胡椒属植物中首次报道的成分。结果证明了在福建长期以来被认为是山药的腺鳞蒟与模式产地的山药有较大差别,尤其是腺鳞蒟叶上表面有腺鳞,是迄今为止第1个发现具有腺鳞的胡椒属植物。据此把腺鳞蒟作为新变种从山药中分出。腺鳞药是福建南部海风藤主要来源之一。  相似文献   
43.
44.

Background

The purpose of our investigation was to compare quantitative T2 relaxation time measurement evaluation of lumbar intervertebral discs with morphological grading in young to middle-aged patients with low back pain, using a standardized region-of-interest evaluation approach.

Patients and methods

Three hundred thirty lumbar discs from 66 patients (mean age, 39 years) with low back pain were examined on a 3.0 T MR unit. Sagittal T1-FSE, sagittal, coronal, and axial T2-weighted FSE for morphological MRI, as well as a multi-echo spin-echo sequence for T2 mapping, were performed. Morphologically, all discs were classified according to Pfirrmann et al. Equally sized rectangular regions of interest (ROIs) for the annulus fibrosus were selected anteriorly and posteriorly in the outermost 20% of the disc. The space between was defined as the nucleus pulposus. To assess the reproducibility of this evaluation, inter- and intraobserver statistics were performed.

Results

The Pfirrmann scoring of 330 discs showed the following results: grade I: six discs (1.8%); grade II: 189 (57.3%); grade III: 96 (29.1%); grade IV: 38 (11.5%); and grade V: one (0.3%). The mean T2 values (in milliseconds) for the anterior and the posterior annulus, and the nucleus pulposus for the respective Pfirrmann groups were: I: 57/30/239; II: 44/67/129; III: 42/51/82; and IV: 42/44/56. The nucleus pulposus T2 values showed a stepwise decrease from Pfirrmann grade I to IV. The posterior annulus showed the highest T2 values in Pfirrmann group II, while the anterior annulus showed relatively constant T2 values in all Pfirrmann groups. The inter- and intraobserver analysis yielded intraclass correlation coefficients (ICC) for average measures in a range from 0.82 (anterior annulus) to 0.99 (nucleus).

Conclusions

Our standardized method of region-specific quantitative T2 relaxation time evaluation seems to be able to characterize different degrees of disc degeneration quantitatively. The reproducibility of our ROI measurements is sufficient to encourage the use of this method in future investigations, particularly for longitudinal studies.  相似文献   
45.
Painful skeletal metastases are a common problem in cancer patients. Although external beam radiation therapy is the current standard of care for cancer patients who present with localized bone pain, 20–30% of patients treated with this modality do not experience pain relief, and few further options exist for these patients. For many patients with painful metastatic skeletal disease, analgesics remain the only alternative treatment option. Recently, image-guided percutaneous methods of tumor destruction have proven effective for treatment of this difficult problem. This review describes the application, limitations, and effectiveness of percutaneous ablative methods including ethanol, methyl methacrylate, laser-induced interstitial thermotherapy (LITT), cryoablation, and percutaneous radiofrequency ablation (RFA) for palliation of painful skeletal metastases.  相似文献   
46.
47.
Consumer‐directed care is increasingly becoming a mainstream option in community‐based aged care. However, a systematic review describing how the current evaluation research translates into practise has not been published to date. This review aimed to systematically establish an evidence base of user preferences for and satisfaction with services associated with consumer‐directed care programmes for older people. Twelve databases were searched, including MedLine, BioMed Central, Cinahl, Expanded Academic ASAP, PsychInfo, ProQuest, Age Line, Science Direct, Social Citation Index, Sociological Abstracts, Web of Science and the Cochrane Library. Google Scholar and Google were also searched. Eligible studies were those reporting on choice, user preferences and service satisfaction outcomes regarding a programme or model of home‐based care in the United States or United Kingdom. This systematic narrative review retrieved literature published from January 1992 to August 2011. A total of 277 references were identified. Of these 17 met the selection criteria and were reviewed. Findings indicate that older people report varying preferences for consumer‐directed care with some demonstrating limited interest. Clients and carers reported good service satisfaction. However, research comparing user preferences across countries or investigating how ecological factors shape user preferences has received limited attention. Policy‐makers and practitioners need to carefully consider the diverse contexts, needs and preferences of older adults in adopting consumer‐directed care approaches in community aged care. The review calls for the development of consumer‐directed care programmes offering a broad range of options that allow for personalisation and greater control over services without necessarily transferring the responsibility for administrative responsibilities to service users. Review findings suggest that consumer‐directed care approaches have the potential to empower older people.  相似文献   
48.
Paul Goetz 《Phytothérapie》2012,10(4):267-270
This editorial review of medicinal plant publications, focusing on pharmacological and clinical research, was written for its pharmaceutical and medical value. It is hoped that it will help advance additional studies that could lead to therapeutic applications. Readers must, however, be aware that a pharmacological breakthrough or the demonstration of pharmacological activity does not immediately justify medical use.  相似文献   
49.
50.
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