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   2322篇
  免费   118篇
  国内免费   30篇
耳鼻咽喉   10篇
儿科学   116篇
妇产科学   56篇
基础医学   206篇
口腔科学   41篇
临床医学   131篇
内科学   322篇
皮肤病学   48篇
神经病学   114篇
特种医学   356篇
外科学   413篇
综合类   156篇
预防医学   104篇
眼科学   124篇
药学   158篇
  1篇
中国医学   9篇
肿瘤学   105篇
  2023年   17篇
  2022年   19篇
  2021年   46篇
  2020年   26篇
  2019年   22篇
  2018年   48篇
  2017年   31篇
  2016年   36篇
  2015年   53篇
  2014年   75篇
  2013年   88篇
  2012年   123篇
  2011年   129篇
  2010年   84篇
  2009年   71篇
  2008年   122篇
  2007年   136篇
  2006年   90篇
  2005年   88篇
  2004年   75篇
  2003年   83篇
  2002年   70篇
  2001年   60篇
  2000年   54篇
  1999年   51篇
  1998年   54篇
  1997年   46篇
  1996年   45篇
  1995年   31篇
  1994年   25篇
  1993年   29篇
  1992年   26篇
  1991年   38篇
  1990年   22篇
  1989年   64篇
  1988年   48篇
  1987年   38篇
  1986年   45篇
  1985年   36篇
  1984年   18篇
  1983年   20篇
  1982年   28篇
  1981年   16篇
  1980年   23篇
  1979年   15篇
  1978年   20篇
  1977年   18篇
  1976年   13篇
  1975年   9篇
  1973年   7篇
排序方式: 共有2470条查询结果,搜索用时 14 毫秒
41.
Recent work has shown that vasoactive intestinal peptide (VIP), one of the many candidate hormones of the gut, also occurs widely in neurones. To determine whether the neuronal peptide may have a neurotransmitter function, we studied changes in immunoreactive VIP in dog plasma and human cerebrospinal fluid after the infusion of choline esterase inhibitors (neostigmine and physostigmine, respectively). Immunoreactive VIP was released in both situations. The systemic changes (in VIP levels) were enhanced five weeks after portacaval shunting in dogs. Our results demonstrate that the immunoreactive VIP level increases as a result of choline esterase inhibitors. The plasma "release" may originate either from peripheral peptidinergic nerve terminals or from APUD cells of the gastroenteropancreatic system. The increase in immunoreactive cerebrospinal fluid VIP may very well originate from central neurons, since the peptide does not apparently cross the blood-brain barrier.  相似文献   
42.
目的观察小分割分次立体定向放射治疗(fractionated stereotatic radiation therapy,FSRT)脑转移瘤的近期疗效.方法15例病人单纯全脑外照射(WBRT组),中间平面剂量20~40Gy/10~20次/2~4周.17例病人接受FSRT(FSRT组),每次分次剂量为2.5~3.0Gy.其中11病人行单纯FSRT,中心总剂量为30~60Gy/1 0~20次/2~4周;6例病人先行WBRT,然后行FSRT,中心总剂量为46~60Gy/5~6周.结果KSP评分增加10分以上者,WBRT组为5 3.3%,FSRT组为82.4%.(P<0.05).WBRT组有效率(CR PR)为50.0%;FSRT组有效率(CR PR)为80.0%.中位生存率:WBRT组为3.5月,FSRT组为10.0月.结论FSRT能有效地控制脑转移瘤,减轻神经系统症状,提高生存质量,延长病人生存期,而没有增加副作用,值得临床推广应用.  相似文献   
43.
44.
45.
46.
Health-related quality of life must be a factor when treatment options are discussed with a patient. Quality of life is measured by validated questionnaires that include generic and disease-targeted measures. Urinary and rectal symptoms and sexual function are evaluated after treatment for prostate cancer. Quality of life is adversely affected in the early post-brachytherapy period primarily by the urinary morbidity. Urinary symptoms peak 2 months after treatment and decline thereafter, although severe long-term urinary toxicity occurs in 3% to 12% of patients. Urinary symptoms are generally treated with alpha-blocker and anticholinergic drugs, but 2% to 5% of patients require transurethral resection of the prostate to relieve persistent obstruction. However, 6 months after treatment, overall satisfaction is excellent, and the majority of patients would recommend the procedure to a friend.  相似文献   
47.
Sarcomas--like leukemias, which are also mesodermal malignancies--carry biological significance disproportionate to their clinical frequency. Identification of mutations and translocations associated with these tumors has illuminated aberrant signaling pathways that cause these diseases, determine their behavior, and are therapeutic targets. Activated receptor-associated tyrosine kinase c-kit, mutated in most gastrointestinal stromal tumors, has proven a clinically effective target for enzyme inhibition. A translocation involving a single gene family, consisting of EWS and related genes, has been identified in five different sarcomas, and its chimeric protein products could prove similarly amenable to inhibitors. Resolution of the histopathological complexity is being aided by data from molecular and chromosomal characterization. Improvements in imaging, definition of prognostic factors, and surgical and radiotherapeutic treatment have resulted in improved local control. Continued progress will depend on further adapting the rapidly evolving technologies of genomics and proteomics. It will also depend upon accurate histopathological diagnosis based on validated reagents and consistent methodologies applied to adequate tissue samples derived from patients with complete clinical data. Finally, multicenter, coordinated trials, such as those that occurred with assessment of imatinib mesylate in metastatic gastrointestinal stromal tumors, will assure the most rapid reductions in morbidity and mortality.  相似文献   
48.
49.
Hecht  SS; Ronai  ZA; Dolan  L; Desai  D; Amin  S 《Carcinogenesis》1998,19(1):157-160
We compared the tumor-initiating activities toward mouse skin of two structurally related polycyclic aromatic hydrocarbon diol epoxides: racemic anti-1,2,3,4-tetrahydro-5,6-dimethylchrysene-1,2-diol-3,4- epoxide (5,6-diMeCDE) and racemic anti-1,2,3,4-tetrahydro-5- methylchrysene-1,2-diol-3,4-epoxide (5-MeCDE). Tumors induced by these diol epoxides were analysed for mutations in the Ha-ras gene. 5,6- diMeCDE is derived from the non-planar parent compound 5,6- dimethylchrysene, and reacts to approximately equal extents with dA and dG in DNA, whereas 5-MeCDE is derived from a nearly planar parent compound, 5-methylchrysene, and reacts mainly with dG in DNA. 5,6- diMeCDE, at initiating doses of 33, 100 or 400 nmol per mouse, induced 1.2, 2.2 and 6.2 skin tumors per mouse, respectively. It was significantly less tumorigenic than 5-MeCDE which induced 3.1, 7.5 and 9.1 skin tumors per mouse at the same doses. Tumors induced by 5,6- diMeCDE had a large number of CAA-->CTA mutations in codon 61 of the Ha- ras gene: 50, 55 and 75% of the tumors analysed had this mutation at the 33, 100 and 400 nmol doses. No mutations were found in codons 12 and 13 in the tumors induced by 5,6-diMeCDE. In contrast, CAA-->CTA mutations in codon 61 were rarely seen in tumors induced by 5-MeCDE. At the highest dose of 5-MeCDE, 20% of the tumors analysed had mutations at G of codons 12 and 13. The results of this comparative study support the hypothesis that mutations in the Ha-ras gene in mouse skin tumors induced by PAH diol epoxides occur as a result of their direct reaction with the gene. However, pathways other than the commonly observed Ha- ras codon 61 mutations are clearly important in mouse skin tumorigenesis by these diol epoxides.   相似文献   
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