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   6157篇
  免费   388篇
  国内免费   30篇
耳鼻咽喉   56篇
儿科学   206篇
妇产科学   92篇
基础医学   900篇
口腔科学   311篇
临床医学   461篇
内科学   1503篇
皮肤病学   227篇
神经病学   548篇
特种医学   76篇
外科学   533篇
综合类   25篇
一般理论   2篇
预防医学   608篇
眼科学   179篇
药学   434篇
中国医学   28篇
肿瘤学   386篇
  2024年   12篇
  2023年   85篇
  2022年   166篇
  2021年   297篇
  2020年   175篇
  2019年   247篇
  2018年   246篇
  2017年   165篇
  2016年   167篇
  2015年   213篇
  2014年   285篇
  2013年   364篇
  2012年   592篇
  2011年   601篇
  2010年   280篇
  2009年   245篇
  2008年   395篇
  2007年   395篇
  2006年   366篇
  2005年   318篇
  2004年   299篇
  2003年   233篇
  2002年   211篇
  2001年   15篇
  2000年   11篇
  1999年   32篇
  1998年   28篇
  1997年   17篇
  1996年   14篇
  1995年   10篇
  1994年   10篇
  1993年   8篇
  1992年   8篇
  1991年   3篇
  1990年   4篇
  1989年   4篇
  1988年   3篇
  1985年   5篇
  1984年   4篇
  1981年   4篇
  1980年   6篇
  1979年   3篇
  1976年   2篇
  1975年   2篇
  1973年   2篇
  1969年   2篇
  1966年   2篇
  1965年   2篇
  1964年   3篇
  1962年   3篇
排序方式: 共有6575条查询结果,搜索用时 203 毫秒
41.
Mantle cell lymphoma (MCL) is a B-cell neoplasm with a relatively aggressive clinical course. There is a very small subgroup of patients who present with atypical lymphocytes in peripheral blood, with or without lymphocytosis, lymphadenopathy, or splenomegaly, and with an indolent clinical course. They frequently show mutated IgV(H) genes and CD5 negativity. We report an asymptomatic elderly patient who presented with a single submandibular lymphadenopathy. The biopsy showed immunophenotype and t(11;14)(q13;q32) consistent with MCL. The abnormal lymphoid population was also detected in peripheral blood and bone marrow. The patient has remained asymptomatic for 5 years without receiving any therapy. It is uncertain whether these cases represent an early-stage event in the development or an indolent form of MCL. The existence of such asymptomatic patients with an indolent clinical course should induce a strict clinical judgment in terms of therapeutic decisions.  相似文献   
42.
Summary The allergic bronchoconstriction in guinea pigs has been attributed mainly to the release of mast cell mediators. Histamine has been involved in the first minutes of the anaphylactic reaction and new-formed compounds in the subsequent response. In this asthma model the vagal influence has been sparsely investigated. In the present work we evaluated the pharmacological modification of the acute allergic bronchoconstrictor response in guinea pigs sensitized to ovalbumin through aerosol exposure. Pyrilamine (20 g/kg), diethylcarbamazine (a lipoxygenase inhibitor, 10 mg/kg) and dexamethasone (4 mg/kg) each reduced the antigen-induced bronchoconstriction throughout the 30 min studied. Indomethacin (3.1 mg/kg) did not modify the response to the antigen. Atropine (2 mg/kg) plus bilateral vagotomy also diminished this response from 5 min onward. On the other hand, from 5 min ahead pyrilamine-resistant bronchoconstriction was partially inhibited by dexamethasone, and it was almost completely blocked during all of the response when atropine plus bilateral vagotomy were added to dexamethasone. Dipyridamole (an inhibitor of the adenosine uptake, 0.4 mg/kg) enhanced the bronchoconstriction, though this was significant only in the 2–5 min time-interval of the response. These results suggest that histamine and vagal influence play an important role in the whole response to antigen, that other mediators, probably leukotrienes, participate in this response from 5 min onward, and that adenosine could exert a potentiation effect on this response. Send offprint requests to L. M. Montaño at the Instituto Nacional de Enfermedades Respiratorias  相似文献   
43.
European Journal of Clinical Microbiology & Infectious Diseases - This study determined the carriage rates and antimicrobial resistance (AMR) genes of enterococci from...  相似文献   
44.
45.
These experiments were performed to examine the effects of graded doses of diazepam, flurazepam, or lorazepam given to Swiss-Webster mice either 30 min prior to training or immediately after training in a one-trial inhibitory (passive) avoidance task. A 350 A footshock was administered following entry into a darkened compartment and retention was tested three days later. Doses of 10.0 mg/kg diazepam and 20.0 mg/kg lorazepam given before training significantly impaired acquisition, while 1.0 mg/kg flurazepam, given immediately after training, produced retrograde amnesia. These results indicate that benzodiazepines affect memory processes and that various drugs of the benzodiazepine family differentially affect acquisition and memory consolidation.  相似文献   
46.
47.
PURPOSE: T-Cell lymphomas constitute heterogeneous and aggressive tumors in which pathogenic alterations remain largely unknown. Expression profiling has demonstrated to be a useful tool for molecular classification of tumors. EXPERIMENTAL DESIGN: Using DNA microarrays (CNIO-OncoChip) containing 6386 cancer-related genes, we established the expression profiling of T-cell lymphomas and compared them to normal lymphocytes and lymph nodes. RESULTS: We found significant differences between the peripheral and lymphoblastic T-cell lymphomas, which include a deregulation of nuclear factor-kappaB signaling pathway. We also identify differentially expressed genes between peripheral T-cell lymphoma tumors and normal T lymphocytes or reactive lymph nodes, which could represent candidate tumor markers of these lymphomas. Additionally, a close relationship between genes associated to survival and those that differentiate among the stages of disease and responses to therapy was found. CONCLUSIONS: Our results reflect the value of gene expression profiling to gain insight about the molecular alterations involved in the pathogenesis of T-cell lymphomas.  相似文献   
48.
Thallium (Tl+) toxicity has been related with the generation of reactive oxygen species (ROS) and oxidative stress (OS) in the central nervous system. Since changes in endogenous antioxidant systems might contribute to acute Tl+-induced OS and neurotoxicity, in this study we measured the metal concentration and the levels of lipid peroxidation (LP) in different brain regions (hypothalamus (Ht); cerebellum (Ce); striatum (S); hippocampus (Hc) and frontal cortex (Cx)) in possible correlation with the content of reduced glutathione (GSH), the activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD), and the animal performance in behavioral tests, all evaluated after a single administration of thallium acetate (8 or 16 mg/kg, i.p.) to rats. Seven days after Tl+ administration, the metal was homogeneously and dose-dependently accumulated in all regions evaluated. LP was increased in Ht, Ce and S, while GSH was depleted in S. Cu,Zn-SOD activity was also decreased in Ht and S. All these changes occurred with 16 mg/kg dose and at 7 days after treatment, but not at 1 or 3 days. In addition, Tl+-treated animals exhibited general hypokinesis, but no changes were observed in spatial learning. Our findings suggest that a delayed response of the brain to Tl+ may be the result of its residual levels. Also, despite the regional alterations produced by Tl+ in LP and the limited changes in endogenous antioxidants, there is a correlation between the Tl+-induced oxidative damage and the affected behavioral tasks, suggesting that, although still moderate, Tl+ evokes neurotoxic patterns under the experimental conditions tested.  相似文献   
49.
Eggplant (Solanum melongena) has been used as hypocholesterolemic agent in many countries. However, few controlled studies were addressed to this subject and atherogenesis. We have evaluated the effect of eggplant on cholesterol metabolism and atherogenesis in LDLR(-/-) mice. Animals were fed on chow (n=17) or atherogenic (n=21) diet during 12 weeks receiving water (control) or eggplant extract. Liver, serum and fecal lipids, together with serum lipoproteins were measured. Oxidative stress was evaluated through conjugate diene formation and ox-LDL antibodies by enzyme immunoassay. Atherosclerotic lesions were measured in different sites of aorta. Total cholesterol and atherogenic lipoproteins did not decrease after eggplant intake. Animals receiving eggplant and chow diet showed increased anti-ox-LDL antibodies and a decreased lag phase of conjugated diene formation, indicating a higher oxidative stress than controls. No differences were seen in lesion area of aortic valve. Eggplant extract had high histamine and other amine levels that could enhance LDL oxidation and its endocytosis. Eggplant did not decrease plasma cholesterol nor prevent the development of atherosclerosis in LDLR(-/-) mice. Surprisingly, eggplant increased oxidative stress, representing a risk factor for atherosclerosis. These results did not support the use of eggplant extract as hypocholesterolemic agent.  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