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   27678篇
  免费   1655篇
  国内免费   173篇
耳鼻咽喉   356篇
儿科学   863篇
妇产科学   836篇
基础医学   2794篇
口腔科学   805篇
临床医学   2260篇
内科学   6037篇
皮肤病学   572篇
神经病学   1272篇
特种医学   857篇
外国民族医学   9篇
外科学   5036篇
综合类   801篇
现状与发展   1篇
一般理论   23篇
预防医学   1928篇
眼科学   804篇
药学   2416篇
中国医学   177篇
肿瘤学   1659篇
  2023年   387篇
  2022年   1102篇
  2021年   1548篇
  2020年   836篇
  2019年   1051篇
  2018年   1392篇
  2017年   842篇
  2016年   890篇
  2015年   986篇
  2014年   1196篇
  2013年   1503篇
  2012年   2121篇
  2011年   2154篇
  2010年   1106篇
  2009年   895篇
  2008年   1337篇
  2007年   1430篇
  2006年   1262篇
  2005年   1132篇
  2004年   1043篇
  2003年   898篇
  2002年   823篇
  2001年   367篇
  2000年   346篇
  1999年   326篇
  1998年   185篇
  1997年   132篇
  1996年   110篇
  1995年   123篇
  1994年   78篇
  1993年   67篇
  1992年   141篇
  1991年   134篇
  1990年   125篇
  1989年   122篇
  1988年   113篇
  1987年   105篇
  1986年   109篇
  1985年   93篇
  1984年   81篇
  1983年   100篇
  1982年   42篇
  1981年   61篇
  1980年   45篇
  1979年   83篇
  1978年   47篇
  1977年   60篇
  1976年   51篇
  1975年   47篇
  1974年   42篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
12.
13.
14.
BACKGROUND/AIMS: The purpose of this work was to develop a new sensor for objective in vivo measurement of the cutaneous temperature based on micro-electro-mechanical systems (MEMS), and to compare these performances with those of a classical thermocouple. Research on this new sensor was carried out to allow the quantification of the thermal properties of the made-up skin. METHODS: Sixteen female subjects divided into two different age groups (18-35 and >50 years old) were recruited for this study. Several zones of the face and forearms were made up at random with foundations containing or not a thermoregulator raw material. The quantity of foundation applied on the skin was standardized and measurements were carried out first before make-up, and then 10 s and 5 min after make-up. The new sensor and the thermocouple were used successively on each zone. The cutaneous temperature was expressed in degrees celsius. RESULTS/CONCLUSION: The two systems are similar in terms of repeatability and reproducibility, with some differences in sensibility. The data measured by the MEMS sensor appear lower than those measured by the thermocouple. After make-up, the MEMS sensor detects a progressive increase of the temperature in time whereas the thermocouple detects a decrease. We found the same evolution on the face but in a more attenuated way. These results tend to show that the devices do not measure the same phenomenon. The thermocouple appears more sensitive to the thermal response of the made-up surface whereas the MEMS sensor appears more sensitive to the heat transfers in the interface between the skin and make-up.  相似文献   
15.
16.
Background: Gastrointestinal stromal tumors (GIST) are one of the most common mesenchymal tumors of the gastrointestinal tract. GIST are defined by positive immunohistochemical staining for KIT or CD34 and thus are generally diagnosed after surgery. Because small GIST are rarely diagnosed before surgery, the clinical course of these small tumors is not clear. The aim of the present study was to follow changes in size and configuration of small GIST that were pathologically confirmed using endoscopic ultrasonography‐guided fine‐needle aspiration biopsy (EUS‐FNAB). Methods: Between July 1997 and December 2003, 16 tumors in 16 patients (10 men and 6 women) with an immunohistochemical diagnosis of GIST were regularly followed in our hospital. The median patient age when EUS‐FNAB was performed was 62 years (range 26–82 years) and the median follow‐up period was 4.9 years (range 0.5–9.6 years). Results: Fourteen tumors showed no remarkable changes in size and shape during follow up compared with the initial diagnosis. Two tumors enlarged: one tumor approximately doubled its diameter in 8 years and the other tumor increased from 1.8 cm at diagnosis to up to 10 cm after only 2 years. Doubling time of the latter tumor was calculated as 3.1 months. Conclusions: We conclude that EUS‐FNAB might be a good modality for final diagnosis of GIST without surgery, and that GIST without rapid growth on follow up can be endoscopically followed.  相似文献   
17.
18.
A total of 3,604 primary malignant tumours diagnosed histologically at the Departments of Pathology in Jordan during the period 1975-1979 were analysed. The relative frequency by age, sex and site of these tumours and age-standardised incidence rate are presented. Truncated standardised incidence rates for selected tumours were compared in Jordan and other countries. Except for the urinary bladder tumours, there is a striking resemblance between Jordan and other Middle Eastern countries in the pattern of tumour-occurrence in most sites. Skin malignancies are the dominant tumours in the general and male population, breast in female population and lymphomas in children. Noteworthy are the histologically advanced bladder cancers and the relatively young females affected by breast cancer at first diagnosis. Childhood tumours comprised 7.4% of the total cancers in the present study.  相似文献   
19.
Summary Deaza-aminopterin is a folate analog which is transported more rapidly than methotrexate into cells and appears to be more active than methotrexate against human and animal tumor in vitro. Fifteen patients with advanced urothelial tract cancer were given deaza-aminopterin 30–37.5 mg/m2 IV QW. In responding patients drug was given QOW after 4–6 consecutive doses. Doses were escalated or de-escalated by 7.5 mg/m2 depending on toxicity. Twelve patients had received prior chemotherapy which included methotrexate in nine. Three patients achieved a partial remission lasting 1, 3, and 3 months respectively: all responders had previously failed methotrexate after an initial response to a methotrexate containing regimen. None of the six patients who were methotrexate naive responded to deaza-aminopterin; 3 subsequently received methotrexate without response. Mild mucositis was universal and in 5 was severe. Six patients had an increase in liver transaminases probably secondary to anti-folate hepatotoxicity. Other toxicities included diarrhea, nausea, skin rash and fever. Further studies are needed to define the precise efficacy of deaza-aminopterin in patients with urothelial tract cancers.  相似文献   
20.
For the separate development of radioimmunoassay procedures for thioridazine and its two major active metabolites, mesoridazine and sulforidazine, three haptens, respectively, 2-methylthio-, 2-methylsulfinyl-, and 2-methylsulfonyl-substituted 10-[2-[l-(2-carboxyethyl)-2-piperidinyl]ethyl]-10H-phenothiazine, were synthesized and characterized. Thioridazine hapten was coupled to bovine serum albumin, whereas the haptens for mesoridazine and sulforidazine were coupled to porcine thyroglobulin. The number of hapten residues per mole of carrier protein was determined in each case by an ultraviolet spectrophotometric method. Polyclonal antibodies to each hapten–protein conjugate were obtained in rabbits, and titers of the antisera were checked by evaluating their binding characteristics to the appropriate tritiated analyte. A hapten for the ring sulfoxide metabolite of thioridazine was also synthesized.  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