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   18271篇
  免费   1473篇
  国内免费   549篇
耳鼻咽喉   184篇
儿科学   299篇
妇产科学   404篇
基础医学   2298篇
口腔科学   342篇
临床医学   2258篇
内科学   3108篇
皮肤病学   331篇
神经病学   1143篇
特种医学   717篇
外国民族医学   6篇
外科学   2114篇
综合类   1619篇
现状与发展   1篇
一般理论   2篇
预防医学   1152篇
眼科学   517篇
药学   1706篇
  10篇
中国医学   498篇
肿瘤学   1584篇
  2024年   41篇
  2023年   208篇
  2022年   531篇
  2021年   729篇
  2020年   443篇
  2019年   514篇
  2018年   499篇
  2017年   481篇
  2016年   456篇
  2015年   682篇
  2014年   797篇
  2013年   821篇
  2012年   1308篇
  2011年   1370篇
  2010年   849篇
  2009年   692篇
  2008年   968篇
  2007年   975篇
  2006年   931篇
  2005年   851篇
  2004年   744篇
  2003年   663篇
  2002年   579篇
  2001年   510篇
  2000年   446篇
  1999年   435篇
  1998年   175篇
  1997年   172篇
  1996年   184篇
  1995年   164篇
  1994年   119篇
  1993年   91篇
  1992年   205篇
  1991年   184篇
  1990年   160篇
  1989年   138篇
  1988年   132篇
  1987年   108篇
  1986年   108篇
  1985年   103篇
  1984年   78篇
  1983年   70篇
  1982年   57篇
  1981年   55篇
  1980年   47篇
  1979年   60篇
  1978年   50篇
  1977年   33篇
  1975年   27篇
  1974年   43篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The interpretation of chronic bioassay tests for carcinogenicity requires that the data be appropriately recorded. A "case history" for each animal links the pathology data for each organ of each animal to the length of its life. This information can be used in interpretation of the tumor incidences in light of the survival information. The role of historical controls was discussed, and the use of significance tests in a multidisciplinary approach to the assessment of the pattern of tumor response was suggested. Multiple comparison methods valid for the interpretation of continuous (or measurement) data do not apply to the discrete data analyses used in these studies. The ideas and methods of these studies were applied to an animal study of chloroform.  相似文献   
72.
73.
心外管道全腔肺动脉吻合术的临床应用   总被引:8,自引:1,他引:7  
Wu Q  Chu J  Zhu J  Liu P  Zhang H 《中华外科杂志》2000,38(11):847-849
目的 评价心外管道全腔肺动脉吻合术的临床应用价值。方法 1998年6月~1999年8月,10例先天性心脏复杂畸形的患者接受了心外管道全腔肺动脉吻合术。包括单心室8例,均伴有完全性大动脉转位;右心室发育不良2例。均在全麻低温体外循环下手术。结果 患者全部治愈出院。术后随访6~18个月,无晚期死亡。所有患者症状消失,无静脉压明显升高现象,超声检查显示心外管道血流通畅,无血栓形成;心电图检查显示无严重心  相似文献   
74.
To examine whether endogenous androgens influence the occurrence of prostate cancer, we conducted a nested case-control study among participants enrolled in the Carotene and Retinol Efficacy Trial. We analyzed serum samples of 300 cases diagnosed between 1987 and 1998, and 300 matched controls. Higher concentrations of testosterone (T) were not associated with increased prostate cancer risk. Relative to men with levels in the lowest fourth of the distribution, men in the upper fourth of total T had a risk of 0.82 [95% confidence interval (CI), 0.52-1.29]. The corresponding relative risks for free T (0.72; 95% CI, 0.45-1.14), percentage of free T (0.74; 95% CI, 0.46-1.19), and total T:sex hormone binding globulin ratio (0.52; 95% CI, 0.32-0.83) similarly were not elevated. Higher concentrations of androstenedione, dehydroepiandrosterone sulfate, and 3 alpha-androstanediol glucuronide were weakly associated with risk. Relative risks associated with being in the highest fourth for androstenedione, dehydroepiandrosterone sulfate, and 3 alpha-androstanediol glucuronide were 1.20 (95% CI, 0.76-1.89), 1.38 (95% CI, 0.86-2.21), and 1.27 (95% CI, 0.80-2.00), respectively. Men in the upper fourth of total estradiol (E2), free E2 and percentage of free E2 had relative risks of 0.71 (95% CI, 0.42-1.13), 0.52 (95% CI, 0.33-0.82), and 0.65 (95% CI, 0.40-1.05), respectively. The inverse association between E2 and prostate cancer risk was largely restricted to men with blood collection within 3 years of diagnosis. Our results add to the evidence that serum testosterone is unrelated to prostate cancer incidence. The suggestions that intraprostatic androgen activity may increase risk and that serum estrogens may decrease risk, warrant additional study.  相似文献   
75.
中药脑肺康对地鼠实验性肺气肿及肺动脉高压的防治作用   总被引:2,自引:0,他引:2  
目的 观察中药肺康对缺氧性肺动脉高压和肺气肿的防治效果并探讨其作用机制。方法 以弹性蛋白酶溶液滴注入金黄地鼠气管内,正常饲养30d后,常压下缺氧15d,分别设立中药脑肺康预防组、治疗组、肺气肿+缺氧组及正常对照组。于处死动物前,测量平均肺动脉压,取静脉血进行循环内皮细胞计数;处死后测量右心肥大指数,光镜下计数左侧肺支气管肺泡灌洗液内细胞总数,对右侧肺进行光镜图像分析。结果 中药脑肺康预防组和治疗3  相似文献   
76.
采用数字减影血管造影技术超选择性动脉栓塞治愈2例血管搏动怀耳鸣,并就发病原因、机理、治疗措施、临床特征进行讨论。  相似文献   
77.
Z Zhang  J Liu  X Shang  J Yang  J Chu  Z Wang  Z Yao  H Ma  Q Li  Y Wang 《中国中药杂志》1998,23(2):104-6, inside back cover
It has been proved that Rhodiola Capsules can obviously decrease the oxygen consumption of myocardium and oxygen consumption index in anesthetic dogs, decrease the coronary artery resistance, but have no marked effect on the coronary artery blood flow. The Capsules also have the function of decreasing blood presure and slowing heart rate.  相似文献   
78.
Between July 1997 and August 1998 we investigated three clusters (26 cases) of ciguatera poisoning in the inner Sydney area. Tropical reef fish were implicated in each cluster. Most of those affected had musculoskeletal, neurological and gastrointestinal symptoms. The clusters raise questions about the need for rapid diagnosis and enhanced surveillance mechanisms, the regulation of fish supply, and the lack of testing facilities for ciguatera toxin.  相似文献   
79.
PURPOSE: To study the incidence of adverse events after i.v. injection of MR contrast agents in a Chinese population. A comparison was made between an ionic contrast agent (dimeglumine gadopentetate, Magnevist) and a non-ionic contrast agent (gadodiamide, Omniscan). MATERIAL AND METHODS: During a 24-month period, 2,049 Chinese patients who randomly received an i.v. bolus injection of either Magnevist or Omniscan were investigated. All patients were questioned for the presence of any generalized or localized adverse reaction on the following day after the MR examination according to a standardized questionnaire. RESULTS: Three hundred and nine out of 2,049 patients (15%) reported an adverse event. There was a higher incidence of adverse events in patients receiving Magnevist as compared to those receiving Omniscan injection. All reported adverse events were clinically mild and required neither treatment nor hospitalization. CONCLUSION: There was a higher incidence of adverse reaction in patients receiving Magnevist than in those receiving Omniscan.  相似文献   
80.
Chu ZG  Zhou FM  Hablitz JJ 《Brain research》2000,887(2):203-405
In the neocortex, fast excitatory synaptic transmission can typically be blocked by using excitatory amino acid (EAA) receptor antagonists. In recordings from layer II/III neocortical pyramidal neurons, we observed an evoked excitatory postsynaptic potential (EPSP) or current (EPSC) in the presence of EAA receptor antagonists (40-100 microM D-APV+20 microM CNQX, or 5 mM kynurenic acid) plus the GABA(A)-receptor antagonist bicuculline (BIC, 20 microM). This EAA-antagonist resistant EPSC was observed in about 70% of neurons tested. It had a duration of approximately 20 ms and an amplitude of 61.5+/-6.8 pA at -70 mV (n=35). The EAA-antagonist resistant EPSC current-voltage relation was linear and reversed near 0 mV (n=23). The nonselective nicotinic acetylcholine receptor (nAChR) antagonists dihydro-beta-erythroidine (DH beta E, 100 microM) or mecamylamine (50 microM) reduced EPSC amplitudes by 42 (n=20) and 33% (n=9), respectively. EPSC kinetics were not significantly changed by either antagonist. Bath application of 10 microM neostigmine, a potent acetylcholinesterase inhibitor, prolonged the EPSC decay time. EAA-antagonist resistant EPSCs were observed in the presence of antagonists of metabotropic glutamate, serotonergic (5-HT(3)) and purinergic (P2) receptors. The EAA-antagonist resistant EPSC appears to be due in part to activation of postsynaptic nAChRs. These results suggest the existence of functional synaptic nAChRs on pyramidal neurons in rat neocortex.  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