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   10327篇
  免费   987篇
  国内免费   349篇
耳鼻咽喉   33篇
儿科学   91篇
妇产科学   57篇
基础医学   1195篇
口腔科学   283篇
临床医学   832篇
内科学   1179篇
皮肤病学   108篇
神经病学   573篇
特种医学   376篇
外科学   468篇
综合类   1447篇
一般理论   1篇
预防医学   1759篇
眼科学   127篇
药学   2103篇
  4篇
中国医学   655篇
肿瘤学   372篇
  2024年   19篇
  2023年   124篇
  2022年   208篇
  2021年   461篇
  2020年   387篇
  2019年   322篇
  2018年   323篇
  2017年   359篇
  2016年   401篇
  2015年   397篇
  2014年   672篇
  2013年   776篇
  2012年   591篇
  2011年   669篇
  2010年   493篇
  2009年   488篇
  2008年   445篇
  2007年   412篇
  2006年   396篇
  2005年   339篇
  2004年   285篇
  2003年   297篇
  2002年   239篇
  2001年   205篇
  2000年   165篇
  1999年   173篇
  1998年   160篇
  1997年   158篇
  1996年   129篇
  1995年   122篇
  1994年   119篇
  1993年   104篇
  1992年   106篇
  1991年   97篇
  1990年   91篇
  1989年   97篇
  1988年   93篇
  1987年   75篇
  1986年   73篇
  1985年   88篇
  1984年   76篇
  1983年   56篇
  1982年   59篇
  1981年   46篇
  1980年   47篇
  1979年   50篇
  1978年   38篇
  1977年   42篇
  1976年   29篇
  1975年   22篇
排序方式: 共有10000条查询结果,搜索用时 297 毫秒
41.
本文分析了101例成人骨灰样品和5例成人尸解样品中镭-226和钙的含量。实验范围内,人骨中镭-226含量与年龄及骨中钙含量呈二元线性相关关系。用苏州市人口相应的年龄构成计权的人骨中镭-226含量为(5.99+0.08)×10-4Bq/g灰。所测各部位骨的骨灰中镭-226含量的差异无显著性意义;不同部位骨的灰化率差异甚大,由尸解样品中镭-226含量估算的人体软组织中镭-226负荷量约占全身负荷量的20%。此外,本文还根据所测骨、肺、肝,胃,小肠、大肠、骨胳肌和皮肤中镭-226含量,对相应受辐射危险的组织进行了剂量估算,并估算了接受镭-226及其短寿命子体所致年剂量后随机性健康效应发生的几率,将随机性建康效应发生的几率与世界癌症发病率最低的国家或地区的相应组织或器官的癌症发病率相比较,发现前者比后者至少低约二个数量级。  相似文献   
42.
用免疫组织化学ABC法,研究了降钙素基因相关肽(CGRP)免疫反应神经纤维在大鼠胆总管末端与十二指肠连接处的分布。大鼠的胆总管末端有较丰富的CGRP免疫反应神经纤维,它们多呈串珠(膨体)状,少数为无膨体的细长纤维。CGRP-IR纤维主要分布肌层及血管周围,在神经纤维的附近可见到含CGRP-IR阳性颗粒的肥大细胞。本实验为神经免疫调节机制的研究提供了形态学依据。  相似文献   
43.
Hospital discharge data from New Jersey were used to identify cases of asbestosis for the 8 years 1979-1986. Multiple admissions were deleted so that each individual was counted once at the time of his/her first hospitalization with an asbestosis diagnosis. White males had the highest age-adjusted average annual discharge rate of 19.3 cases/100,000 population, followed by black males (12.3 cases/100,000) and white females (1.2 cases/100,000). The discharge rate was positively associated with age in each race/sex category. The relationship between rates for black males and white males depended on age: under 65 years, the rates were almost equal, and at 65 years and older, the white rates were nearly twice the black rates. There were two areas of the state where the rates were highest: the north-central and southwest regions. These two areas represent manufacturing and shipbuilding applications of asbestos, respectively. During the years 1979-1986, the annual percentage increase in asbestosis rates was 20% for white males, 17% for black males, and 8% for white females. Continued surveillance will reveal when the rates for asbestosis stop increasing.  相似文献   
44.
对食管癌高发区粮食中分离的互隔交链孢霉的毒素交链孢酚单甲醚(AME)在大鼠、小鼠体内的分布进行研究。给动物腹腔内注射氚标记的交链孢酚单甲醚(~3H-AME),然后在不同时间测各脏器的放射性。结果表明:在所测9个脏器中,2h肝脏含量最高,食管下段在大小鼠分别居第四和第三。但大小鼠分别在72、24h则以食管下段最高,说明AME及其代谢物在此清除较慢,即对其有较高的亲和力。  相似文献   
45.
This study analyzed the effect of population aging on organ donation for transplants in 43 countries and on the effectiveness of the donation process by comparing the results between Spain and the United States. The percentage of the population aged 65 or over accounted for 33% of the difference in the donation rates between the countries and for 91% of the variation in the rates after age adjustment. However, the level of aging of the Spanish (16.5%) and American (12.3%) populations failed to account for the percentages of deceased donors 65 or over (28% vs. 10%), due to the different age-specific donation rates, much higher in Spain above 50 years. These differences lead to a higher effectiveness of the process in the United States (3.1 transplanted organs per donor vs. 2.5 in Spain), though at lower rates of transplant per million population (73 vs. 87). We conclude that older populations have a greater donation potential as donation rates are strongly associated with population aging. It should therefore be mandatory to adjust donation rates for age before making comparisons. Additionally, effectiveness decreases with older donors, so age should be considered when establishing standards relating to organ donation and effectiveness of the process.  相似文献   
46.
本文详细介绍了在新疆发现的花蠕形蚤、叶氏蠕形蚤、北山羊蠕形蚤、羊长喙蚤和狍长喙蚤的形态学特点、地理分布和某些生物学特性。  相似文献   
47.
大鼠直肠壁内淋巴管的微细分布和形态特征   总被引:4,自引:0,他引:4  
目的观察大鼠直肠壁内淋巴管的分布和形态、结构特点,为探讨直肠癌淋巴道转移的机制,提供形态学依据。方法用半薄、超薄切片、光镜和电镜下观察大鼠淋巴管的微细分布。结果大鼠直肠壁的黏膜固有层深部可见毛细淋巴管,黏膜下层、肌层和浆膜层均有毛细淋巴管和淋巴管。结论直肠壁各层内均有毛细淋巴管,除黏膜层外,还存有淋巴管。  相似文献   
48.
Distribution of Evans Blue (EB), sucrose, and water into the isolated perfused rat hindlimb was studied under various conditions using the multiple indicator dilution (MID) technique. Statistical moment analyses of the outflow profiles for the EB, sucrose, and water were used to define the vascular, extravascular, and total water spaces, respectively. The varied perfusion conditions included albumin content (2, 4.7, and 7%), temperature (25, 37, and 42 C), perfusate flow rate (2, 4, 8, and 12 ml/min) and the presence/absence of red blood cells. The range of studies undertaken were chosen to represent the variety of conditions used in the preparation of both isolated animal and human limbs, the latter being particularly important in cytotoxic therapy for recurrent malignant melanoma. The distribution volumes of EB, sucrose, and water were dependent on the flow rate and the albumin content of perfusate. The normalized variances (CV 2 ) of the markers were of the following order: sucrose (2.18) > water (1.58) > EB (0.68), indicating that some disequilibrium occurs during the capillary exchange of water and sucrose. It is suggested that a Krebs-Henseleit buffer containing 2% BSA is a suitable perfusate for most studies of the isolated rat hindlimb perfusion. The effect of albumin concentration manifests itself only at higher flows.We acknowledge the support of the National Heart Foundation (Queensland) and the Mayne Bequest Foundation. This study was conducted while the investigator (Z.Y. Wu) was in receipt of a WHO Research Training Grant. Professor M. S. Roberts also acknowledges the support of the Queensland and Northern New South Wales Lions Kidney & Medical Research Foundation.  相似文献   
49.
Objective: In order to document the stereoselective distribution in joints of a chiral nonsteroidal anti-inflammatory drug, the relative affinities of the enantiomers of tiaprofenic acid in synovium and for cartilage were compared. Methods: The distribution of tiaprofenic acid in synovium and in cartilage was studied 25 h after administering the racemic drug for 2 days (600 mg of a sustained-release preparation, once daily), in 12 inpatients with osteoarthritis of the hip requiring arthroplasty. Enantiomers were quantified in plasma and freeze-ground tissues by a chiral HPLC assay. Results: Plasma concentrations of the dextrorotatory (R) enantiomer (0.40 μg/ml) were higher than those of its antipode. The concentration of racemate in synovium (in dried and fresh tissues, 150% and 40%, respectively, of the concentration in plasma) was much higher than that in cartilage (in dried tissues 32% of the plasma concentration). The ratio of the active, dextrorotatory (R) enantiomer to its antipode was higher in synovial tissue than in plasma. Conclusion: Tiaprofenic acid is distributed stereoselectively in plasma and synovium, which contain a higher concentration of the active, dextrorotatory (R) enantiomer. In cartilage, it reaches only a very low concentration. Received: 26 June 1995/Accepted in revised form: 7 November 1995  相似文献   
50.
应用圆分布分析法对莱芜市22年间两次伤寒流行的发病时间进行了分析。第一次流行在1958年—1968年共发生2239例,按月发病时间计算的平均角度为287.4°(291天),发病高峰在10月18日。第二次流行在1975年—1985年共发生606例,平均角度为294.5°(299天),发病高峰在10月26日。对两个平均角进行显著性检验,F=9.4,P<0.01。即两次流行发病时间的平均角间有高度显著性差异。  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