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   18232篇
  免费   1162篇
  国内免费   254篇
耳鼻咽喉   411篇
儿科学   201篇
妇产科学   331篇
基础医学   3020篇
口腔科学   325篇
临床医学   1503篇
内科学   3559篇
皮肤病学   884篇
神经病学   1171篇
特种医学   1348篇
外科学   2296篇
综合类   53篇
一般理论   9篇
预防医学   521篇
眼科学   384篇
药学   1856篇
中国医学   274篇
肿瘤学   1502篇
  2024年   7篇
  2023年   166篇
  2022年   539篇
  2021年   823篇
  2020年   398篇
  2019年   552篇
  2018年   643篇
  2017年   557篇
  2016年   817篇
  2015年   1147篇
  2014年   1261篇
  2013年   1352篇
  2012年   1983篇
  2011年   1817篇
  2010年   1136篇
  2009年   843篇
  2008年   1107篇
  2007年   981篇
  2006年   887篇
  2005年   759篇
  2004年   526篇
  2003年   473篇
  2002年   375篇
  2001年   93篇
  2000年   63篇
  1999年   60篇
  1998年   50篇
  1997年   31篇
  1996年   19篇
  1995年   16篇
  1994年   23篇
  1993年   17篇
  1992年   11篇
  1991年   15篇
  1990年   8篇
  1989年   10篇
  1988年   11篇
  1987年   9篇
  1986年   7篇
  1984年   12篇
  1982年   6篇
  1981年   6篇
  1980年   2篇
  1979年   2篇
  1978年   3篇
  1976年   3篇
  1974年   3篇
  1972年   3篇
  1971年   2篇
  1969年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Total vaginal or abdominal hysterectomy was considered an inadequate treatment method for invasive uterine cervix cancer. Usually the procedure was inadvertently performed on patients who were thought preoperatively to have benign or premalignant conditions. Between 1985 and 1993, 64 patients undergoing hysterectomy in the presence of invasive cervical cancer were treated with external radiation therapy and/or intracavitary radiotherapy. Preoperative diagnoses were carcinomain situ(36), severe dysplasia (2), and early invasive cancer (14), and others were benign disease. Overall 5-year survival and relapse-free survival rates were 75.8 and 77.5%, respectively. For patients in retrospective stage IA, IB, and IIB (gross residual after surgery), overall 5-year survival rates were 90.9, 88.8, and 27.9%, respectively. Thirteen patients developed treatment failure; most of them (10/13) were patients with gross residual disease. Patients with early invasive cervical cancer (stage IA) had no treatment-related failure. Prognostic factors affecting survival by univariate analysis were retrospective stage (P= 0.0000) and preoperative diagnosis (P= 0.0021). Tumor histology was marginally significant factor (P= 0.0938). By multivariate analysis, only retrospective stage was significant prognostic factor (P= 0.0001). Adjuvant radiotherapy appears to be an effective treatment method for patients with presumed stage IA and IB after inadvertent hysterectomy. Survival for patients with gross disease remaining after inappropriate hysterectomy is poor. So, early cancer detection and proper management with precise pretreatment staging is necessary to avoid inadherent hysterectomy, especially in cases of gross residual disease.  相似文献   
52.
The degradation of the basement membrane by matrix-metalloproteinase(MMP) and serine protease is a critical pointin tumor invasion and metastasis. We measured theactivity of MMP-9 from 28 normal, 12 benignand 126 breast cancer tissues using gelatin zymographywith an image analysis system. ProMMP-9 was expressedin 17.5% of the cancer patients compared to2.5% in 40 non-cancerous tissues (p=0.014).The mature form of MMP-9 (82 kD) wasexpressed only in T2–T4 stages. During the earlyphase of breast cancer (DCIS and T1 stage)progression, only production of proMMP-9 increased. However, asthe cancer grew or invaded skin (T2–T4), orwith lymphovascular permeation, both production and activation ofMMP-9 increased. In conclusion, proMMP-9 production was themain cause of increased MMP-9 activity during theearly phase, while both production and activation increasedin the late phase of breast cancer.  相似文献   
53.
Choi BK  Cho SH  Bai GH  Kim SJ  Hyun BH  Choe YK  Bae YS 《Diabetes》2000,49(9):1459-1467
The D variant of encephalomyocarditis (EMC-D) virus causes diabetes in susceptible mice by direct cytolysis of pancreatic beta-cells. cDNA covering the major outer capsid protein (VP1) of the EMC-D virus was cloned into Mycobacterium bovis bacillus Calmette-Guerin (BCG). None of the SJL/J mice immunized with live recombinant BCG-VP1 (rBCG-VP1) became diabetic when challenged with the highly diabetogenic EMC-D virus, but the control mice inoculated with normal BCG developed diabetes during the same challenge. VP1-specific antibodies (including neutralizing antibodies) were markedly increased over time and reached the maximum titer at week 10 after a single immunization. The plateau of the titer lasted longer than 4 weeks. Mice and guinea pigs immunized with live rBCG-VP1 showed strong delayed-type hypersensitivity to the VP1 of the EMC-D virus. The preventive immunity still worked effectively 10 months after the primary immunization. At that time, the VP1-specific antibody was almost undetectable in the bloodstream, but a large number of VP1-specific lymphocytes was found in the spleen of the immunized mice. Our results show that live rBCG-VP1 elicits effective humoral and long-lasting cellular immune responses against EMC-D virus infection that results in the prevention of virus-induced diabetes in susceptible mice.  相似文献   
54.
55.
ObjectivesDespite sufficient hearing gains, many patients with hearing loss have difficulty using hearing aids due to poor word recognition ability. This study was performed to introduce our hearing rehabilitation therapy (HRT) program for hearing aid users and to evaluate its effect on hearing improvement.MethodsIn this prospective randomized case-control study, 37 participants with moderate or moderate-severe sensorineural hearing loss who had used bilateral hearing aids for more than 3 months with sufficient functional hearing gain were enrolled in this study. Nineteen participants were randomly assigned to the control group (CG) and 18 patients were assigned to participate in our HRT program once a week for 8 consecutive weeks (hearing rehabilitation therapy group [HRTG]). Their hearing results and questionnaire scores for hearing handicap and hearing aid outcomes were prospectively collected and compared between the two groups.ResultsAfter completing 8 weeks of the HRT program, the HRTG showed a significantly greater improvement in scores for consonant-only and consonant-vowel sound perception than the CG (P<0.05). In addition, the HRTG showed a significant improvement in hearing ability as measured by two questionnaires (P<0.05), while no differences were observed in the CG. However, word and sentence recognition test results did not show significant differences between the two groups.ConclusionEven after short-term HRT, patients had subjectively better hearing outcomes and improved phoneme perception ability; this provides scientific evidence regarding a possible positive role for HRT programs in hearing aid users. Further validation in a larger population through a long-term follow-up study is needed.  相似文献   
56.
BACKGROUND/OBJECTIVESZanthoxylum schinifolium is traditionally used as a spice for cooking in East Asian countries. This study was undertaken to evaluate the anti-proliferative potential of ethanol extracts of Z. schinifolium leaves (EEZS) against human bladder cancer T24 cells.MATERIALS/METHODSSubsequent to measuring the cytotoxicity of EEZS, the anti-cancer activity was measured by assessing apoptosis induction, reactive oxygen species (ROS) generation, and mitochondrial membrane potential (MMP). In addition, we determined the underlying mechanism of EEZS-induced apoptosis through various assays, including Western blot analysis.RESULTSEEZS treatment concentration-dependently inhibited T24 cell survival, which is associated with apoptosis induction. Exposure to EEZS induced the expression of Fas and Fas-ligand, activated caspases, and subsequently resulted to cleavage of poly (ADP-ribose) polymerase. EEZS also enhanced the expression of cytochrome c in the cytoplasm by suppressing MMP, following increase in the ratio of Bax:Bcl-2 expression and truncation of Bid. However, EEZS-mediated growth inhibition and apoptosis were significantly diminished by a pan-caspase inhibitor. Moreover, EEZS inhibited activation of the phosphoinositide 3-kinase (PI3K)/Akt pathway, and the apoptosis-inducing potential of EEZS was promoted in the presence of PI3K/Akt inhibitor. In addition, EEZS enhanced the production of ROS, whereas N-acetyl cysteine (NAC), a ROS scavenger, markedly suppressed growth inhibition and inactivation of the PI3K/Akt signaling pathway induced by EEZS. Furthermore, NAC significantly attenuated the EEZS-induced apoptosis and reduction of cell viability.CONCLUSIONSTaken together, our results indicate that exposure to EEZS exhibits anti-cancer activity in T24 bladder cancer cells through ROS-dependent induction of apoptosis and inactivation of the PI3K/Akt signaling pathway.  相似文献   
57.
Although silicon dioxide (SiO2), silver (Ag) and iron oxide (Fe2O3) nanoparticles are widely used in diverse applications from food to biomedicine, in vivo toxicities of these nanoparticles exposed via the oral route remain highly controversial. To examine the systemic toxicity of these nanoparticles, well‐dispersed nanoparticles were orally administered to Sprague–Dawley rats daily over a 13‐week period. Based on the results of an acute toxicity and a 14‐day repeated toxicity study, 975.9, 1030.5 and 1000 mg kg–1 were selected as the highest dose of the SiO2, Ag and Fe2O3 nanoparticles, respectively, for the 13‐week repeated oral toxicity study. The SiO2 and Fe2O3 nanoparticles did not induce dose‐related changes in a number of parameters associated with the systemic toxicity up to 975.9 and 1000 mg kg–1, respectively, whereas the Ag nanoparticles resulted in increases in serum alkaline phosphatase and calcium as well as lymphocyte infiltration in liver and kidney, raising the possibility of liver and kidney toxicity induced by the Ag nanoparticles. Compared with the SiO2 and Fe2O3 nanoparticles showing no systemic distribution in all tissues tested, the Ag concentration in sampled blood and organs in the Ag nanoparticle‐treated group significantly increased with a positive and/or dose‐related trend, meaning that the systemic toxicity of the Ag nanoparticles, including liver and kidney toxicity, might be explained by extensive systemic distribution of Ag originating from the Ag nanoparticles. Our current results suggest that further study is required to identify that Ag detected outside the gastrointestinal tract were indeed a nanoparticle form or ionized form. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
58.
Bioassay-guided fractionation of an 80% MeOH extract of leaves and twigs of Juglan sinensis has resulted in the isolation of four new triterpenes (1-4) and 17 known triterpenes (5-21). The new compounds were determined to be 1-oxo-3β,23-dihydroxyolean-12-en-28-oic acid 28-O-β-D-glucopyranoside (1), 1-oxo-3β-hydroxyolean-18-ene (2), 3β,23-dihydroxyurs-12-en-28-oic acid 28-O-β-D-glucopyranoside (3), and 3β,22α-dihydroxyurs-12-en-28-oic acid 28-O-β-D-glucopyranoside (4) by spectroscopic analysis. Compounds 2, 13, 15, and 21 showed antiproliferative activities (14.2, 14.8, 15.6, and 11.0% at 100 μM, respectively) in HSC-T6 cells. Flow cytometry assays revealed that these compounds inhibited HSC-T6 proliferation by inducing apoptosis.  相似文献   
59.
60.
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