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   307977篇
  免费   17695篇
  国内免费   483篇
耳鼻咽喉   4379篇
儿科学   10410篇
妇产科学   10429篇
基础医学   46266篇
口腔科学   8102篇
临床医学   24991篇
内科学   58591篇
皮肤病学   6649篇
神经病学   21679篇
特种医学   12047篇
外国民族医学   43篇
外科学   48664篇
综合类   7817篇
现状与发展   1篇
一般理论   160篇
预防医学   20295篇
眼科学   7322篇
药学   21540篇
中国医学   810篇
肿瘤学   15960篇
  2019年   2388篇
  2018年   3797篇
  2017年   2799篇
  2016年   3225篇
  2015年   3640篇
  2014年   4798篇
  2013年   7479篇
  2012年   9580篇
  2011年   9957篇
  2010年   6469篇
  2009年   5798篇
  2008年   9195篇
  2007年   10070篇
  2006年   9857篇
  2005年   9464篇
  2004年   9193篇
  2003年   8615篇
  2002年   8231篇
  2001年   13731篇
  2000年   14163篇
  1999年   11863篇
  1998年   3184篇
  1997年   2894篇
  1996年   2738篇
  1995年   2646篇
  1994年   2422篇
  1992年   8544篇
  1991年   8707篇
  1990年   8524篇
  1989年   8373篇
  1988年   7589篇
  1987年   7304篇
  1986年   6929篇
  1985年   6726篇
  1984年   4890篇
  1983年   4233篇
  1982年   2526篇
  1979年   4567篇
  1978年   3324篇
  1977年   2818篇
  1976年   2573篇
  1975年   2892篇
  1974年   3447篇
  1973年   3436篇
  1972年   3191篇
  1971年   3005篇
  1970年   2898篇
  1969年   2641篇
  1968年   2585篇
  1967年   2417篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
In 1985 an outbreak of ornithosis affected 13 of 80 (16%) workers in a duck-processing plant. New employees were three times more likely to become cases than established employees. The highest attack rate was in those on the production line. Following the outbreak, an occupational health scheme was set up to monitor the health of new recruits to the company. Serological evidence of recent infection was demonstrated in 18 of 37 (49%) new employees tested in the first 3 months of employment. Five (14%) also had clinical evidence of ornithosis. Veterinary investigation of the ducks demonstrated a high proportion with asymptomatic chlamydial infection. It is suggested that ornithosis may be more common in duck processors than is currently supposed. Strategies to reduce occupational risks are discussed.  相似文献   
32.
33.
Most authors consider the principal advantage of FG anastomoses (compared to microsurgical anastomoses) to be shorter operating time, reduced surgical trauma to oviduct stumps, and absence of tissue ischemia. These features promote reparative regeneration and decrease adhesion formation, resulting in complete recanalization of fallopian tubes. To date, the majority of work on FG is confined to the experimental development of surgical techniques. Investigations in reconstructive gynecological surgery are quite uncommon. The physical properties of FG and the positive results of available experimental studies suggest that further development of surgical techniques using FG in obstetrics and gynecology is worthwhile.  相似文献   
34.
Background The appearance of eosinophils is a hallmark sign of the allergic late-phase response (LPR). Eosinophil cationic protein (ECP), a readily measurable product released from activated eosinophils, has so far not been evaluated in the ocular LPR. Objective Two sets of trials were performed in order to investigate changes of local and systemic eosinophil activity and their possible link with symptoms and hyper-reactivity in the allergic LPR in the eye. Methods In the first experiment, ECP was analysed in tears and serum and the clinical reaction was evaluated during a 72-h time–course after a single, high-dose allergen challenge out of season in one eye of 15 pollen-sensitized volunteers. In a second experiment, the hypothesis of an increased clinical response to an allergen challenge in an eye that had been provoked with allergen 48h previously was tested in nine sensitized individuals. Results In the first experiment, symptoms at 10 min and 2, 4, 6, 8 and 24 h significantly exceeded base line scores of the challenged eyes. Tear ECP was significantly elevated in challenged eyes compared to contralateral eyes at 6, 8 and 24 h. In addition, symptoms and ECP release correlated significantly at the 24-h evaluation. Serum ECP remained unchanged throughout the study period. In the second experiment, conjunctival hyperreactivity 48h after an allergen challenge was not confirmed. Conclusion ECP secretion occurs in the experimental ocular LPR and is in part associated with the magnitude of the clinical reaction, which suggests a truly pathogenic role of the activated eosinophil in pollen-induced allergic conjunctivitis.  相似文献   
35.
36.
Recurrent erosion   总被引:1,自引:0,他引:1  
  相似文献   
37.
Electrocardiographic symptoms were evaluated in 53 patients with an additional left-ventricular chorda (ALVC), detected by two-dimensional echocardiography. Signs of early ventricular repolarization (EVR) were identified in 45 (84.9%) patients. A transverse ALVC was more common in EVR-free patients (87.5%), as compared to patients with ALVC + EVR combinations (51.1%; p less than 0.05).  相似文献   
38.
Summary Twenty-two patients with recurrent or metastatic squamous cell carcinoma of the head and neck were treated with piroxantrone 150 mg/m2 intravenously every 21 days. There were no objective responses. The 95% upper confidence bound for response is 15%. Primary toxicity was hematologic.  相似文献   
39.
A prognosis of patients with a curative resected advanced cancer of the lower gastric region was worse than that of the other region of the stomach. The 5 year survival rate was only 47.3%. One of the main reasons was that a rate of lymph node recurrence was higher. In this point of view, we studied on lymphatic flow of the lower gastric region using an activated carbon particle (CH40). Lymph nodes were stained black soon after the injection of CH40 into the lower gastric wall at laparotomy. The black stained rate of an each regional lymph node was as follows. 3. 58%, 4. 17%, 5. 50%, 6. 25%, 1. 21%, 7. 58%, 8. 83%, 9. 58%, 11. 17% and 12. 33% in case of injection into the greater curvature and and 4. 31%, 6. 100%, 8. 25%, 9. 25%, 14V and 56% in case of injection into the lesser curvature. The stained rate was relatively high in 12 and 14V lymph node which we had not routinely dissected. The rates of lymph nodes stained black were related to those of cancer metastasis. The results suggest that lymphadenectomy of 12 for the cancer at the lesser curvature and that of 14V for the cancer at the greater curvature might make a prognosis of lower gastric cancer better.  相似文献   
40.
Oil-emulsified (OE) and aqueous (Aq) vaccines were prepared with the same batch of inactivated A24 8345 foot and mouth disease virus (FMDV). Calves born to vaccinated dams did not respond to the Aq vaccine 30 or 90 days post partum. When the OE vaccine was used on a similar group of calves, no responses were elicited up to 21 days post partum. However, calves 30 or more days old responded like adult cattle to the OE vaccine. When the OE vaccine was used in colostral antibody-free calves 3-30 days old, all animals showed good antibody responses but, in calves vaccinated 3 or 7 days post partum, antibodies were detectable only after a considerable period of time. Our results show that both passively acquired colostral antibodies and age are important in the response of very young calves to FMDV oil vaccines. From a practical point of view, in endemic areas where adult cattle are periodically vaccinated, vaccination of calves between 30 and 60 days post partum with OE vaccines would lead to high levels of herd protection.  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