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   1329620篇
  免费   94733篇
  国内免费   2853篇
耳鼻咽喉   19772篇
儿科学   40106篇
妇产科学   38606篇
基础医学   186196篇
口腔科学   39832篇
临床医学   111577篇
内科学   260134篇
皮肤病学   30203篇
神经病学   105779篇
特种医学   53764篇
外国民族医学   435篇
外科学   208218篇
综合类   30951篇
一般理论   436篇
预防医学   91252篇
眼科学   31321篇
药学   99956篇
  2篇
中国医学   2960篇
肿瘤学   75706篇
  2018年   11621篇
  2015年   11828篇
  2014年   16703篇
  2013年   25293篇
  2012年   33200篇
  2011年   35068篇
  2010年   20787篇
  2009年   20277篇
  2008年   33720篇
  2007年   36845篇
  2006年   37406篇
  2005年   36174篇
  2004年   35248篇
  2003年   34205篇
  2002年   33752篇
  2001年   63627篇
  2000年   65253篇
  1999年   55112篇
  1998年   13894篇
  1997年   12658篇
  1996年   12133篇
  1995年   12175篇
  1994年   11431篇
  1992年   42787篇
  1991年   41360篇
  1990年   40597篇
  1989年   39598篇
  1988年   37001篇
  1987年   36474篇
  1986年   34952篇
  1985年   33160篇
  1984年   24833篇
  1983年   21011篇
  1982年   12627篇
  1981年   11516篇
  1980年   10718篇
  1979年   23895篇
  1978年   17035篇
  1977年   14771篇
  1976年   13325篇
  1975年   15204篇
  1974年   18039篇
  1973年   17532篇
  1972年   16785篇
  1971年   15707篇
  1970年   14878篇
  1969年   14317篇
  1968年   13452篇
  1967年   12003篇
  1966年   11256篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Tamoxifen prevents recurrence of breast cancer and is suggested for preventive risk-reducing therapy. Tamoxifen reduces mammographic density, a proxy for therapy response, but little is known about its effects in remodelling normal breast tissue. Our study, a substudy within the double-blinded dose-determination trial KARISMA, investigated tamoxifen-specific changes in breast tissue composition and histological markers in healthy women. We included 83 healthy women randomised to 6 months daily intake of 20, 10, 5, 2.5, 1 mg of tamoxifen or placebo. The groups were combined to “no dose” (0-1 mg), “low-dose” (2.5-5 mg) or “high-dose” (10-20 mg) of tamoxifen. Ultrasound-guided biopsies were collected before and after tamoxifen exposure. In each biopsy, epithelial, stromal and adipose tissues was quantified, and expression of epithelial and stromal Ki67, oestrogen receptor (ER) and progesterone receptor (PR) analysed. Mammographic density using STRATUS was measured at baseline and end-of-tamoxifen-exposure. We found that different doses of tamoxifen reduced mammographic density and glandular-epithelial area in premenopausal women and associated with reduced epithelium and increased adipose tissue. High-dose tamoxifen also decreased epithelial ER and PR expressions in premenopausal women. Premenopausal women with the greatest reduction in proliferation also had the greatest epithelial reduction. In postmenopausal women, high-dose tamoxifen decreased the epithelial area with no measurable density decrease. Tamoxifen at both low and high doses influences breast tissue composition and expression of histological markers in the normal breast. Our findings connect epithelial proliferation with tissue remodelling in premenopausal women and provide novel insights to understanding biological mechanisms of primary prevention with tamoxifen.  相似文献   
2.
3.
Graefe's Archive for Clinical and Experimental Ophthalmology - The purpose was to ascertain if any relation exists between the elevated intraocular pressure (IOP) in patients with...  相似文献   
4.
Oral squamous cell carcinomas (OSCCs) develop in genetically altered epithelium in the mucosal lining, also coined as fields, which are mostly not visible but occasionally present as white oral leukoplakia (OL) lesions. We developed a noninvasive genetic assay using next-generation sequencing (NGS) on brushed cells to detect the presence of genetically altered fields, including those that are not macroscopically visible. The assay demonstrated high accuracy in OL patients when brush samples were compared with biopsies as gold standard. In a cohort of Fanconi anemia patients, detection of mutations in prospectively collected oral brushes predicted oral cancer also when visible abnormalities were absent. We further provide insight in the molecular landscape of OL with frequent changes of TP53, FAT1 and NOTCH1. NGS analysis of noninvasively collected samples offers a highly accurate method to detect genetically altered fields in the oral cavity, and predicts development of OSCC in high-risk individuals. Noninvasive genetic screening can be employed to screen high-risk populations for cancer and precancer, map the extension of OL lesions beyond what is visible, map the oral cavity for precancerous changes even when visible abnormalities are absent, test accuracy of promising imaging modalities, monitor interventions and determine genetic progression as well as the natural history of the disease in the human patient.  相似文献   
5.
Journal of Developmental and Physical Disabilities - Caregiver support is an important contextual factor in the daily functioning of children with cerebral palsy (CP), but few studies have examined...  相似文献   
6.
Graefe's Archive for Clinical and Experimental Ophthalmology - Ferromagnetic foreign bodies (FFB) present during magnetic resonance imaging (MRI) explorations can lead to tissue injury due to...  相似文献   
7.
Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz -  相似文献   
8.
Background: Nanotechnology is receiving greater attention these days as a result of its applications in numerous industrial, medical, and environmental fields. Objective: To synthesize silver nanoparticles with a green alga, Cladophora glomerata, and determine their inhibitory activity against tumor cell (MCF-7) and transgenic mouse cell (L20B) lines. Materials and Methods: Methanol extract was prepared from Cladophora glomerata and used as a safe factory for the synthesis of silver nanoparticles (AgNPs). UV-visible spectrophotometer, X-ray diffraction, scanning electron microscopy, and EDX analyses were used to characterize the biosynthesized AgNPs. The anti-tumor activity of the phycosynthesized AgNPs was tested against the MCF-7 and L20B cell lines. Furthermore, the bioactive compounds in the algal extract were determined by gas chromatography-mass spectroscopy (GC-MS). Results: The phycosynthesis produced clusters of spherical and polydispersed cuboidal pure AgNPs with an average size of 32 nm. The phycosynthesized AgNPs possess anti-cancer and anti-tumor activities on the MCF-7 and L20B cell lines, with significant anti-proliferation percentages of 52.8 and 65.8%, respectively, after 48 hours of treatment with 100 μg/ml AgNPs. Both treated cell lines showed a significant change in cellular shape and tissue detachment. The GC-MS analysis revealed the presence of a high proportion of octadecanoic acid (47.59%) and hexadecanoic acid (14.97%). Conclusion: Cladophora glomerata contains chemicals that improve the stabilization and reduction properties of the nanoparticles. It can be used as a safe, local, and natural source for the synthesis of AgNPs and can also be used as a benign factory for many other metal nanoparticles. The phycosynthesized AgNPs have anti-cancer and anti-tumor activities on the test cell lines and provide an insight into the potential for using them as a trend in cancer nanotherapy.  相似文献   
9.
10.
Breast Cancer Research and Treatment - The NSABP B-36 compared four cycles of doxorubicin and cyclophosphamide (AC) with six cycles of 5-fluorouracil, epirubicin, and cyclophosphamide (FEC-100) in...  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