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   86585篇
  免费   7422篇
  国内免费   2816篇
耳鼻咽喉   717篇
儿科学   2040篇
妇产科学   1228篇
基础医学   8349篇
口腔科学   1184篇
临床医学   8332篇
内科学   8718篇
皮肤病学   835篇
神经病学   2226篇
特种医学   5370篇
外国民族医学   52篇
外科学   10149篇
综合类   14385篇
现状与发展   19篇
预防医学   3085篇
眼科学   610篇
药学   6095篇
  50篇
中国医学   2567篇
肿瘤学   20812篇
  2024年   150篇
  2023年   1160篇
  2022年   2262篇
  2021年   3599篇
  2020年   2911篇
  2019年   2639篇
  2018年   2498篇
  2017年   2852篇
  2016年   3118篇
  2015年   3318篇
  2014年   5544篇
  2013年   5250篇
  2012年   4974篇
  2011年   5663篇
  2010年   4394篇
  2009年   4526篇
  2008年   4565篇
  2007年   4739篇
  2006年   4205篇
  2005年   3725篇
  2004年   3196篇
  2003年   2731篇
  2002年   2432篇
  2001年   2218篇
  2000年   1884篇
  1999年   1672篇
  1998年   1422篇
  1997年   1293篇
  1996年   1110篇
  1995年   1042篇
  1994年   866篇
  1993年   658篇
  1992年   572篇
  1991年   465篇
  1990年   376篇
  1989年   350篇
  1988年   338篇
  1987年   275篇
  1986年   208篇
  1985年   273篇
  1984年   257篇
  1983年   155篇
  1982年   198篇
  1981年   167篇
  1980年   141篇
  1979年   108篇
  1978年   95篇
  1977年   65篇
  1976年   52篇
  1973年   32篇
排序方式: 共有10000条查询结果,搜索用时 750 毫秒
991.
The patient described here, with malignant non-beta islet cell tumor of the head of the pancreas, was treated by resection of the tumor and metastases. Additional pathology of perforated duodenal ulcer and pyloric stenosis required vagotomy and pyloroplasty. The maintenance of normal gastrin levels after the operation indicates a good prognosis. We believe that the low-risk Zollinger-Ellison patient should be treated surgically and the tumor removed. When no tumor can be detected, parietal cell vagotomy should be performed to assist the pharmacological control of the gastric acid hypersecretion. Extensive surgery, such as total gastrectomy, is no longer the treatment of choice and is reserved for the so-called "cimetidine failure."  相似文献   
992.
Summary Diethylstilbestrol (DES), diethylstilbestrol monophosphate (DES-MP) and diethylstilbestrol diphosphate (DES-DP) were tested for their estrogen receptor affinity, estrogenic potency and mammary tumor-inhibiting activity in vitro and in vivo. DES had a much higher receptor binding affinity than its mono-or diphosphate. All three compounds inhibited the growth of the hormone-dependent MCF-7 and hormone-independent MDA-MB 231 breast cancer line only at relatively high concentrations. The estrogenic potency in the immature mouse uterine weight test decreased in the order DES>DES-MPDES-DP. The hormone-dependent MXT mammary tumor of the mouse was inhibited by all three compounds at a dosage of 1.0 mg/kg per week. At a dose of 0.01 mg/kg, DES, DES-MP, and DES-DP stimulated the tumor growth. Thus, for the first time, a biphasic effect on tumor growth was demonstrated in intact mature animals. As the effects of all three compounds were similar in this assay, a cleavage of the phosphate groups is likely. A decrease in estrogenic potency concomitant with a retained antitumor effect of DES-MP and DES-DP compared to DES was not demonstrable in the mature mouse using the MXT assay, only in the uterotrophic test in the immature mouse.Dedicated to Professor Dietrich Schmähl on occasion of his 60th birthdaySupported by the Deutsche Forschungsgemeinschaft and by the Verband der Chemischen Industrie, Fonds der Chemischen Industrie. The authors thank Dr. Weigert, Asta-Werke AG, Degussa Pharma Gruppe, Bielefeld, FRG, for the analysis of DES-MP and DP  相似文献   
993.
Conditions which suppress spontaneous breathing activity during high-frequency jet ventilation (HFJV) were analysed in Yorkshire piglets under pentobarbital anesthesia. The highest PaCO2 at which the animals did not breathe against the ventilator (apnea point) was established during different patterns of ventilation, either by changing the minute volume or by adding CO2 to the inspiratory gas. Arterial oxygen tension was maintained throughout the study above 80 mm Hg. An elevation of ventilatory rate increased the apnea point, suggesting a progressive suppression of spontaneous breathing. This suppression did not depend on the amount of lung stretch during insufflation, because at higher rates lower tidal volumes were used. Suppression also appeared to be independent of insufflatory flow, i.e. the velocity of lung stretch. At higher frequencies end-expiratory airway pressure (PEE) increased and there appeared to be a positive relationship between the apnea point and PEE. In a separate series this positive relationship between the apnea point and PEE was confirmed. A hysteresis effect in this relationship, however, suggests that other than jet frequency, lung volume rather than positive end-expiratory pressure (PEEP) is a major determinant of suppression of spontaneous breathing activity during HFJV.  相似文献   
994.
A case of "sclerosing hemangionia" (pneumocytoma) of the lungwith lymph node metastasis is reported. A 22-year-old Japaneseman was found to have a well-defined round lesion in the rightlung (S7), which increased in size slightly during a 2-yearfollow-up period. He underwent right lower lobectomy with a preoperative diagnosisof a benign lung tumor. The pulmonary tumor revealed histologicalfeatures characteristic of "sclerosing hemangioma" of the lung,in addition to which there were many large polygonal foamy cells,forming tubular or papillary structures. These cells were foundby electron microscopy to contain numerous cytoplasmic lamellarbodies and showed a positive reaction with anti-surfactant apoproteinantibody immunohistochemically. Therefore, they were consideredto be cells differentiating toward type II pneumocytes. Reviewof 21 typical "sclerosing hemangionia" disclosed a few or somesuch foamy cells in 10 cases. A single hilar lymph node wasthe site of microscopic metastases, which consisted of "largeclear foamy cells" and smaller polygonal or round cells withslightly eosinophilic cytoplasm, both of which were componentsof the pulmonary "sclerosing hemangioma" This case supportsthe theory that "sclerosing hemangioma" is a neoplasm of typeII pneumocyte lineage. Although it is said to be benign, rarecases apparently show metastatic potential.  相似文献   
995.
癌光啉对动物移植瘤的光化学诊治作用   总被引:11,自引:0,他引:11  
本文报道了肿瘤光化学诊治新药癌光啉(PsD-007)对三种动物移植瘤(S_(180)肉瘤、Lewis肺癌、U_(14)宫颈癌)的实验性光化学诊治效果,初步探讨了辐照光能量和药物剂量与肿瘤实验性诊治效果的关系。作者采用“透镜光阑”法改善辐射光斑内功率密度分布的不均匀性。提供了一种能比较客观地评价药物对动物移植瘤的光动力学治疗效价的模型体系。  相似文献   
996.
Summary -Adrenoceptors of lung (75% 2) and heart (95% 1) of calf were labelled with 3H-(–)-propranolol. The stereoisomers of 10 ligands were used to inhibit the binding of 3H-(–)-propranolol to membrane particles. The affinity ratio of sereoisomers is consistently greater for 1-adrenoceptors than for 2-adrenoceptors, regardless of whether the ligands are agonists, partial agonists or antagonists. The 1-adrenoceptor appears to possess stricter steric requirements than the 2-adrenoceptor. This property may prove helpful in differentiating the -adrenoceptor subtypes during receptor solubilization and purification.  相似文献   
997.
AT1727 is a derivative of ICRF 154. The purpose of this study was to evaluate its "radiosensitizer" properties. From October 1979 until the end of December 1980, 89 patients with radiation resistant cancers such as soft tissue sarcoma, squamous lung cancer (with large lesion, 6-8 cm diameter) and other cancers had been included in trial. Radiation therapy was carried out using CO60 or 8 Mev Linac. Fifty-five patients had a remarkable objective remission rate of 61.8% (55/89). Eighteen of 30 patients with soft tissue sarcomas obtained obvious remission (60%), and 26 of 38 patients with lung cancer had remission (68.4%). Patients with esophageal cancer (5/6) and nasopharyngeal cancer (5/5) also had good remission rates. The side-effects of this treatment were very mild: anorexia and vomiting were noted in 50% and no significant changes were noted in liver and kidney function tests and blood platelet count. Leucopenia was slight in all but one patient. No difference in the lung fibrosis rate was noted between the two randomized groups. From the results of this study we concluded that AT1727 had some effect as a "radiosensitizer" but much more work is needed to confirm this.  相似文献   
998.
目的了解郑州市二七区居民2011—2020年恶性肿瘤死亡流行趋势及对居民寿命的影响情况,为制定恶性肿瘤防治对策提供科学依据。方法对2011—2020年郑州市二七区居民恶性肿瘤死亡资料进行分析,计算恶性肿瘤死亡率、潜在减寿年数(potential years of life lost,PYLL)、标化潜在减寿年数(standardized potential years of life lost,SPYLL)、标化潜在减寿率(standardized potential years of life lost rate,SPYLLR)和人均减寿年数(average years of life lost,AYLL)等指标,采用年度变化百分比(annual percent change,APC)分析率的时间变化趋势。结果2011—2020年郑州市二七区居民恶性肿瘤年均死亡率为114.68/10万,标化死亡率为103.52/10万,男性年均死亡率(146.09/10万)高于女性(84.56/10万)。恶性肿瘤前5位死因依次为肺癌、肝癌、胃癌、结直肠癌和食管癌,共占恶性肿瘤死亡构成的65.36%。2011—2020年该区居民恶性肿瘤死亡率呈上升趋势(APC=3.70%,P<0.001)。0~44岁年龄组恶性肿瘤死亡率处于较低水平,45岁后随年龄增长逐渐升高,75岁以后迅速升高。恶性肿瘤总PYLL为39067人年,SPYLLR为6.73‰,AYLL为12.59年。结论肺癌、肝癌、胃癌、结直肠癌和食管癌是二七区恶性肿瘤预防控制的重点工作,同时宫颈癌和乳腺癌对女性健康的影响不可忽视,应针对主要恶性肿瘤和重点人群开展综合防控措施,以降低恶性肿瘤的死亡率。  相似文献   
999.
目的 分析大气污染物与浦东新区居民每日肺癌死亡人数的相关性,为制定针对肺癌病人的保护措施提供依据。方法 采集浦东新区2005年1月1日至2019年12月31日之间的每日大气污染物浓度、气象因素以及居民肺癌死亡资料,利用时间分层-病例交叉设计并结合分布滞后非线性模型,探讨大气污染物短期暴露对浦东新区居民肺癌死亡的影响。结果 大气污染物(PM10, SO2, NO2)浓度与浦东新区居民肺癌死亡风险呈正相关。PM10, SO2, NO2浓度对居民肺癌死亡风险的影响均在累积8 d(Lag 0~7)最强。PM10, SO2, NO2浓度上升10 μg/m3累积8 d(Lag 0~7)居民肺癌死亡风险分别上升1.09%(95%CI:0.35%~1.83%), 3.78%(95%CI:1.98%~5.61%)与2.76%(95%CI:1.10%~4.44%)。女性人群肺癌死亡对PM10与NO2的影响不敏感(P>0.05)。大气污染物对高龄人群与低文化水平人群肺癌死亡效应较强,人群间效应差异不显著。结论 大气污染物短期暴露可以升高浦东新区居民肺癌死亡风险,以累积8 d(Lag 0~7)效应最强。  相似文献   
1000.
目的 评估重庆市2011—2020年结核病防治经费投入产生的社会效益。方法 收集《传染病监测系统》中2011—2020年重庆市登记涂阳肺结核患者(初治涂阳和复治涂阳)治疗转归情况和肺结核患者劳动人口比例,历年各级政府结核病防治经费投入,历年全市人均国内生产总值(gross domestic product,GDP)等数据,采用常用卫生经济学方法评估10年间结核病防治经费投入的社会效果、社会效用和社会效益。结果 2011—2020年,全市共投入结核病防治经费约3.60亿元,成功治疗涂阳肺结核患者60 924例,避免45.69万名健康人受传染,挽救43.41万个伤残调整生命年(disability adjusted life year,DALY),为社会节约医疗费用3.26亿元,挽回社会经济损失约176.25亿。保持目前的设施设备和人员条件不变,每投入787.70元即可避免1名健康人被传染,每投入829.16元即可挽救1个DALY,每额外投入1元即可产生49.87元的经济效益。结论 10年间重庆市结核病防治经费投入产生了较大的卫生经济效益,建议各级政府继续加大结核病防治经费投入。  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