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   14106篇
  免费   1560篇
  国内免费   100篇
耳鼻咽喉   109篇
儿科学   347篇
妇产科学   363篇
基础医学   2344篇
口腔科学   244篇
临床医学   1584篇
内科学   3061篇
皮肤病学   204篇
神经病学   924篇
特种医学   959篇
外科学   1792篇
综合类   340篇
一般理论   7篇
预防医学   1390篇
眼科学   228篇
药学   1040篇
中国医学   14篇
肿瘤学   816篇
  2021年   230篇
  2020年   132篇
  2019年   205篇
  2018年   253篇
  2017年   183篇
  2016年   196篇
  2015年   228篇
  2014年   318篇
  2013年   450篇
  2012年   637篇
  2011年   678篇
  2010年   437篇
  2009年   378篇
  2008年   582篇
  2007年   646篇
  2006年   623篇
  2005年   572篇
  2004年   527篇
  2003年   499篇
  2002年   474篇
  2001年   439篇
  2000年   439篇
  1999年   415篇
  1998年   251篇
  1997年   218篇
  1996年   221篇
  1995年   228篇
  1994年   193篇
  1993年   200篇
  1992年   352篇
  1991年   355篇
  1990年   300篇
  1989年   321篇
  1988年   273篇
  1987年   287篇
  1986年   277篇
  1985年   298篇
  1984年   242篇
  1983年   186篇
  1982年   143篇
  1981年   122篇
  1980年   106篇
  1979年   162篇
  1978年   131篇
  1977年   112篇
  1976年   111篇
  1975年   109篇
  1974年   110篇
  1973年   108篇
  1972年   96篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
We report the case of a patient with a 13-year history of pemphigus vulgaris (PV) treated with immunosuppressive agents, prednisone and mycophenolate mofetil who had developed lesions of Kaposi's sarcoma (KS) on a sole plaque of PV that had been previously treated with intralesional injections of steroids. The lesions were surgically removed and polymerase chain reaction (PCR) demonstrated human herpesvirus-8 (HHV-8) DNA. There were neither recurrences nor later dissemination of KS following gradual decrease of the immunosuppressive therapy. We suggest that the treatment with intralesional steroids may have influenced the local reactivation of a latent infection of the virus, determining the appearance of this localized KS.  相似文献   
4.
Summary Eight patients with malignant gliomas verified on CT scan, received an intravenous injection of 50 mg of Adriamycin R, 24 hours prior to surgical removal of the tumour. Peroperatively, both tumour and surrounding tissue specimens were obtained for determination of the tissue concentrations of Adriamycin and its reduced metabolite Adriamycinol. It was found that Adriamycin could be detected in tumour tissue from all patients. The concentration varied between 0,9 and 4,6 nmol/g tissue. In contrast, Adriamycin could only be detected in surrounding brain tissue from one patient.In anin vitro study a human malignant glioma cell line (U-251 MG) was exposed to various concentrations of Adriamycin for 24 hours. It was found that an intracellular drug concentration above 30 nmol/g cells caused a concentration dependent inhibition of cell growth. Thus, it is likely that the poor effect of Adriamycin on patients with malignant gliomas is due to an ineffective drug accumulation in the tumour tissue.  相似文献   
5.
The effects of acetazolamide on the developing rodent limb bud were postulated to result from a reduction of intracellular pH (pHi). Embryonic intracellular pH was calculated from transplacental distribution of the weak acid, 5,5'-dimethyloxazolidine-2,4-dione, in teratogenically sensitive (C57BL/6) and resistant (SWV) inbred mice. pHi was reduced by acetazolamide treatment in C57 embryos and limb buds but not in SWV samples. Acetazolamide teratogenesis can be exacerbated by coadministration of amiloride, presumably through inhibition of Na+/H+ exchange attributable to the latter agent. pHi reduction after such treatment was more profound than after acetazolamide alone, providing further support for the central hypothesis. pH was also reduced in other embryonic (embryo plasma) and extraembryonic compartments (exocoelomic fluid, amniotic fluid). pH changes in these compartments could also lead or contribute to abnormal development.  相似文献   
6.
In the pituitary gland, activating mutations of the GNAS1 (Gsalpha) gene at Gln227 have been identified in adrenocorticotrophin secreting, growth hormone secreting, and prolactin secreting adenomas. To date, mutations at the codon encoding R201, typically underlying the McCune-Albright syndrome and isolated fibrous dysplasia of bone, have been demonstrated only in growth hormone secreting pituitary adenomas. In this study, a polymerase chain reaction amplified target sequence in exon 8 of the GNAS1 gene was sequenced, identifying the first R201 mutation seen in an isolated basophilic adenoma which generated Cushing's disease in a child. This case adds Cushing's disease to the range of human diseases caused by R201 mutations of the GNAS1 gene.  相似文献   
7.
8.
9.
BACKGROUND: Cardiac magnetic resonance (MR) images are often reviewed by non-cardiologists who are not trained in the interpretation of regional left ventricular (LV) function. We hypothesized that the use of still-frame parametric MR images of wall motion could aid in the assessment of regional LV function. METHODS: Dynamic, electrocardiogram-gated, steady-state free precession (FIESTA) short-axis images were obtained in 6 to 10 slices in 18 consecutive patients. Each loop was used to automatically generate a still-frame image, in which each pixel is assigned a value equal to the amplitude of cyclic variation in local intensity, resulting in higher intensity in pixels that change between blood and tissue during the cardiac cycle. The dynamic images were reviewed by an expert cardiologist who provided gold standard grades for regional wall motion and by four radiologists. Then the radiologists reviewed and graded the same MR images in combination with parametric images. Grades assigned to each segment in the two sessions were compared with the gold standard. RESULTS: According to expert interpretation, 6 patients had normal wall motion, and 12 had wall motion abnormalities. Parametric images showed a bright band in the area spanned by endocardial motion, with reduced brightness and thickness in areas of hypokinesis. The agreement between the radiologists' grades and the gold standard significantly improved by adding parametric images (from 77% to 81%), which also resulted in reduced interobserver variability (from 52% to 33%). CONCLUSIONS: Still-frame parametric images aid in the assessment of regional wall motion by non-cardiologists who are required to interpret cardiac images.  相似文献   
10.
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