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   1514958篇
  免费   115661篇
  国内免费   4912篇
耳鼻咽喉   18803篇
儿科学   48341篇
妇产科学   40151篇
基础医学   221168篇
口腔科学   40086篇
临床医学   147367篇
内科学   296095篇
皮肤病学   28842篇
神经病学   129301篇
特种医学   54266篇
外国民族医学   380篇
外科学   212717篇
综合类   31992篇
现状与发展   3篇
一般理论   746篇
预防医学   131318篇
眼科学   32832篇
药学   111285篇
  7篇
中国医学   3474篇
肿瘤学   86357篇
  2021年   13870篇
  2019年   14549篇
  2018年   19768篇
  2017年   15078篇
  2016年   16164篇
  2015年   18651篇
  2014年   26037篇
  2013年   39737篇
  2012年   55390篇
  2011年   59149篇
  2010年   34025篇
  2009年   31281篇
  2008年   54264篇
  2007年   57441篇
  2006年   57058篇
  2005年   55906篇
  2004年   53353篇
  2003年   50603篇
  2002年   48910篇
  2001年   62594篇
  2000年   63901篇
  1999年   54145篇
  1998年   17041篇
  1997年   15373篇
  1996年   15057篇
  1995年   14195篇
  1994年   13211篇
  1993年   12387篇
  1992年   42726篇
  1991年   41843篇
  1990年   40461篇
  1989年   38256篇
  1988年   35542篇
  1987年   34665篇
  1986年   33101篇
  1985年   31674篇
  1984年   24365篇
  1983年   20915篇
  1982年   13362篇
  1981年   11744篇
  1979年   21560篇
  1978年   15694篇
  1977年   12913篇
  1976年   12625篇
  1975年   12740篇
  1974年   15431篇
  1973年   15042篇
  1972年   13789篇
  1971年   12766篇
  1970年   11817篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
The use of adjuvant radiation therapy in breast cancer patients treated with mastectomy and adjuvant chemotherapy has been controversial. In order to assess the necessity and effectiveness of adjuvant radiation therapy in this setting, we reviewed the results in 510 patients with T1-T3 tumors and pathologically positive nodes or tumors larger than 5 cm and negative nodes who were treated with adjuvant chemotherapy. Patients with four or more positive nodes or at least one positive apical node were randomized to receive either five or ten cycles of cyclophosphamide/Adriamycin (Adria Laboratories, Columbus, OH) (CA) and patients with one to three positive nodes or operable tumors larger than 5 cm and pathologically negative nodes were randomized to receive eight cycles of either cyclophosphamide, methotrexate, and 5-fluorouracil (5-FU) (CMF) or methotrexate and 5-FU (MF) chemotherapy. Two hundred six of these patients were subsequently rerandomized to receive either no further treatment or adjuvant radiotherapy. Thirty-five patients withdrew after randomization, including 34 who declined to receive radiotherapy. Radiation therapy consisted of 4,500 cGy in 5 weeks to the chest wall and appropriate draining lymph nodes. Median follow-up from chemotherapy randomization is 45 months for patients in the CA arm and 53 months for those in the CMF/MF arm. The crude rate of local failure (chest wall or draining lymph node areas) as first site of failure for patients randomized to receive chemotherapy only was 14%; for those randomized to receive both chemotherapy and radiotherapy it was 5% (P = .03). For patients in the CMF/MF arm, the rate of local failure as the first site of failure was nearly the same for patients randomized to chemotherapy only as for those randomized to adjuvant radiotherapy as well (5% v 2%). For patients in the CA arm, the crude rate of local failure was 20% for patients randomized to receive chemotherapy only, and 6% for those randomized to both types of adjuvant treatment (P = .03). Among the 43 patients treated with CA who actually received radiotherapy, there was only one local failure, compared with 12 local failures among the 59 patients (20%) who actually did not receive radiotherapy (P = .007). No significant difference was seen in disease-free survival or overall survival in either the CA or the CMF/MF arm between patients randomized to receive radiation therapy and those randomized to no further treatment.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
994.
The aim of the study was to determine the effect of exogenous melatonin treatment on circulating prolactin levels in red deer. Melatonin was administered from 12 June 1984 (day 1) to lactating and non-lactating hinds in the feed daily at 1600 h, and to non-lactating hinds by a subcutaneous implant. Average concentrations (ng/ml) of prolactin in plasma taken serially over 15-h periods were significantly higher for untreated hinds than for melatonin-treated animals on day 15 whether lactating (66-133 v. 23-28, P less than 0.05) or non-lactating (28-174 v. 8-13, P less than 0.01), remained higher on day 36 (lactating: 41-152 v. 15-21, P less than 0.05; non-lactating: 21-50 v. 1-7, P less than 0.001) but had decreased to similar levels on day 72 (lactating: 5-24 v. 7-17; non-lactating: 2-9 v. 0-4). The advanced reduction in plasma prolactin for all melatonin-treated hinds was associated with an advanced onset of seasonal breeding activity.  相似文献   
995.
996.
997.
Eight lymphatic fluid collections were drained percutaneously. There were no immediate or late complications. Seven patients had follow-up; 1 required surgical drainage of a residual or recurrent lymphocele, and another had reaccumulated fluid in a lymphocele which was detected on autopsy. The remaining lymphatic collections responded to percutaneous drainage. Percutaneous drainage is safe and can be an effective tool in the management of lymphatic collections.  相似文献   
998.
999.
1000.
These experiments examined the effects, on retention, of posttraining intra-amygdala administration of norepinephrine (NE), and propranolol. Rats were trained on a one-trial step-through inhibitory avoidance task and tested for retention 24 h later. Injections were administered bilaterally (1.0 microliter/injection) through chronically-implanted cannulae. Low doses of NE (0.1 or 0.3 microgram) administered shortly after training enhanced retention while higher doses (1.0 or 5.0 micrograms) were ineffective. Retention was not affected by NE administered 3 h after training. The effect of intra-amygdala NE on retention is blocked by simultaneous administration of propranolol (0.2 microgram). This finding suggests that the memory-enhancing effect of NE may be mediated by beta-receptors. Posttraining intra-amygdala NE also attenuated the retention deficit produced by adrenal demedullation. Further, intra-amygdala injections of propranolol (0.2 microgram) blocked the enhancing effect, on retention, of posttraining s.c. injections of epinephrine. These findings suggest that activation of noradrenergic receptors in the amygdala may be involved in memory processing and may play a role in the memory-modulating effect of peripheral epinephrine.  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