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   1498篇
  免费   93篇
  国内免费   13篇
耳鼻咽喉   5篇
儿科学   50篇
妇产科学   14篇
基础医学   210篇
口腔科学   16篇
临床医学   121篇
内科学   274篇
皮肤病学   56篇
神经病学   118篇
特种医学   147篇
外科学   133篇
综合类   54篇
预防医学   96篇
眼科学   22篇
药学   120篇
中国医学   10篇
肿瘤学   158篇
  2023年   11篇
  2022年   22篇
  2021年   33篇
  2020年   29篇
  2019年   26篇
  2018年   29篇
  2017年   17篇
  2016年   23篇
  2015年   33篇
  2014年   48篇
  2013年   43篇
  2012年   69篇
  2011年   70篇
  2010年   52篇
  2009年   65篇
  2008年   67篇
  2007年   57篇
  2006年   58篇
  2005年   50篇
  2004年   63篇
  2003年   50篇
  2002年   46篇
  2001年   40篇
  2000年   28篇
  1999年   35篇
  1998年   31篇
  1997年   27篇
  1996年   24篇
  1995年   18篇
  1994年   21篇
  1993年   20篇
  1992年   22篇
  1991年   20篇
  1990年   27篇
  1989年   21篇
  1988年   14篇
  1987年   22篇
  1986年   25篇
  1985年   26篇
  1984年   18篇
  1983年   16篇
  1982年   16篇
  1980年   11篇
  1978年   11篇
  1977年   11篇
  1976年   18篇
  1975年   12篇
  1973年   11篇
  1972年   11篇
  1970年   14篇
排序方式: 共有1604条查询结果,搜索用时 31 毫秒
1.
Annals of Surgical Oncology - The role of sentinel lymph node biopsy (SLNB) when ductal carcinoma in situ with microinvasion (DCISM) is identified on core biopsy is unclear. Our aim was to assess...  相似文献   
2.
We examined seven 1-d diet records kept during 1 y by 272 men and women instructed to follow a lipid-lowering diet while participating in a clinical trial of pravastatin, a new 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor. The mean percentage of calories from total fat and saturated, unsaturated, and monounsaturated fatty acids was similar throughout the year even though the patients knew they were taking an effective lipid-lowering agent. However, the diets of greater than 40% of women included less than two-thirds of the recommended dietary allowance (RDA) of folic acid, vitamins B-6 and D, and calcium and zinc; in men, folic acid and zinc intakes were low. We conclude that patients comply with lipid-lowering diets even when they know that they are receiving an effective serum lipid-lowering agent. However, for both men and women special attention should be given to the intake of several nutrients.  相似文献   
3.
The ethanol extracts of the roots of T. cordifolia Miers and C. asiatica Linn were observed to induce a marked protective action against an 8 h restraint stress induced ulcerization, the activity being comparable to that of diazepam.  相似文献   
4.
5.
Occurrence of the t(2;5)(p23;q35) in non-Hodgkin's lymphoma   总被引:9,自引:3,他引:6  
Primary CD30(Ki-1)-positive anaplastic large-cell lymphoma (ALCL) is considered by some to be a distinct clinicopathologic entity associated with the t(2;5) (p23;q35). However, the specificity of t(2;5) for ALCL has not been carefully studied. Therefore, we performed a detailed analysis of all cases of ALCL with abnormal cytogenetics results in the Nebraska Lymphoma Study Group registry, as well as all other cases of non-Hodgkin's lymphoma with t(2;5) in the registry. We found the t(2;5) in only five of 10 cases of ALCL, four of whom were young patients. However, we also found the t(2;5) in 11 other cases of nonanaplastic lymphoma, including eight children with typical peripheral T-cell lymphomas of various types. The t(2;5) was also found in three older adults with B-cell lymphomas of various types. Thus, the t(2;5) was not specific for CD30+ ALCL. However, t(2;5) may define a clinicopathologic entity in children and young adults characterized by variable morphologies with a T-cell or indeterminate phenotype, CD30-positivity, nodal disease with frequent extranodal involvement, advanced stage, and an excellent response to therapy, including bone marrow transplantation for relapsed disease. The clinical relevance of the t(2;5) in older patients requires further study.  相似文献   
6.
Laipcarpine (LC), a pyorrolizidine alkaloid, is able to inducea series of chronic and progressive lesions in rat liver, includingalong-lasting block in the cell cycle, the appearance of enlargedhepatocytes (megalocytosis), fibrosis, cirrhosis and malignantneoplasms. In this study the effect of transplantation of normalhepatocytes on the development of LC (80 µmol/kg i.p.).Four weeks later all animals were subjected to 2/3 paroticlhepatectomy (PH). In addition, at the time of PH one group ofrats were transplanted with normal hepatocytes isolated froma syngeneic donor (106 cells/rat via the portal vein), whilethe other group received only the culture medium. All rats werekilled 14 weeks after the operation. Grossly, the liver of ratsexposed to LC followed by PH with no transplantation of normalhepatocytes was small in size (% liver wt/body wt 1.66 ±0.08) and exhibited a few whitish nodules. Histologically,  相似文献   
7.
8.
The present study was undertaken to determine the effect of two different types of liver cell proliferative stimuli, namely compensatory regeneration and direct hyperplasia on DNA synthesis of normal and preneoplastic isolated hepatocytes. Platelet-poor plasma (PPP) isolated from male Wistar rats treated with three different hepato-mitogens, lead nitrate (LN), cyproterone acetate (CPA) and ethylene dibromide (EDB), or subjected to surgical partial hepatectomy (PH), was tested for its ability to stimulate DNA synthesis in normal and preneoplastic hepatocytes in primary cultures. Induction of DNA synthesis was detected as early as 30 min after CPA, EDB and PH administration and persisted up to 5 days after the LN administration. In addition, hepatocytes isolated from preneoplastic liver nodules were also able to respond in culture to the DNA synthesis stimulus induced by these factors.  相似文献   
9.
Winkler  ML; Olsen  WL; Mills  TC; Kaufman  L 《Radiology》1987,165(1):203-207
Two fast magnetic resonance (MR) imaging techniques, advanced Fourier and partial-flip imaging, were used at 0.35 T to examine 21 patients with suspected intracranial lesions; the results were quantitatively compared with a conventional spin-echo study. Both of the fast MR techniques yielded a fourfold reduction in imaging time per section. The advanced Fourier sequence showed contrast that was identical to the conventional spin-echo study with signal-to-noise ratios of 58% and 57% for the first and second echoes, respectively. The partial-flip sequence showed a contrast of 109% and 57% for lesions versus substantia alba, and 107% and 78% for substantia grisea versus substantia alba relative to the first and second echoes of the conventional spin-echo study. The partial-flip sequence was particularly sensitive to magnetic susceptibility; this produced artifacts that may undermine the usefulness of partial flip for routine screening in certain parts of the brain. However, this susceptibility significantly improved the detection of intracranial hemorrhage when compared with the spin-echo sequence, particularly when combined with phase mapping of the partial-flip study.  相似文献   
10.
A study was undertaken to assess the health, nutrition and psychosocial profile of Institutionalized children in four States--Uttar Pradesh, Andhra Pradesh, Karnataka and West Bengal. A sample of 3,822 children from 70 institutions in 6-18 years age group formed the subjects of the study. It was observed that the destitute children were mainly taken care of in three types of institutions, viz, Voluntary, Government Aided and Government run institutions. Calorie deficiency and deficiency of Vitamins and minerals characterized the diets of these children. In general, there was no deficit of protein in their diets. Growth wise, these children were retarded both in height and weight compared to standards. However, they fared better in comparison to their age and sex counterparts in the rural and urban poor. Psychosocial profile of these children indicated that the prevailing environment in the institutions is less conducive for intellectual stimulation but not so for the development of skills of self-help, locomotion, socialization and imagery.  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