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   12061篇
  免费   392篇
  国内免费   46篇
耳鼻咽喉   144篇
儿科学   291篇
妇产科学   231篇
基础医学   1730篇
口腔科学   415篇
临床医学   1130篇
内科学   2480篇
皮肤病学   197篇
神经病学   1283篇
特种医学   184篇
外科学   1033篇
综合类   43篇
一般理论   5篇
预防医学   1327篇
眼科学   111篇
药学   990篇
  3篇
中国医学   67篇
肿瘤学   835篇
  2024年   92篇
  2023年   114篇
  2022年   256篇
  2021年   459篇
  2020年   297篇
  2019年   394篇
  2018年   403篇
  2017年   291篇
  2016年   292篇
  2015年   344篇
  2014年   521篇
  2013年   645篇
  2012年   1007篇
  2011年   1052篇
  2010年   516篇
  2009年   476篇
  2008年   755篇
  2007年   805篇
  2006年   673篇
  2005年   654篇
  2004年   600篇
  2003年   508篇
  2002年   468篇
  2001年   57篇
  2000年   56篇
  1999年   66篇
  1998年   91篇
  1997年   75篇
  1996年   50篇
  1995年   48篇
  1994年   48篇
  1993年   39篇
  1992年   34篇
  1991年   28篇
  1990年   26篇
  1989年   16篇
  1988年   19篇
  1987年   20篇
  1986年   17篇
  1985年   23篇
  1984年   19篇
  1983年   16篇
  1982年   20篇
  1981年   13篇
  1980年   12篇
  1979年   13篇
  1978年   9篇
  1976年   7篇
  1974年   7篇
  1973年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Maternal and Child Health Journal - To ascertain the component of the excess preterm birth (<?37 weeks, PTB) rate among US-born (compared to foreign-born) Black women...  相似文献   
23.

Syphilis among men who have sex with men (MSM) has increased greatly in the past twenty years in the U.S. Geographically explicit ecological momentary assessment (GEMA), in which behaviors are geotagged and contextualized in time and space, may contribute to a greater understanding of transmission risk. The objective was to determine the acceptability and feasibility of GEMA for assessing HIV and syphilis transmission risk behaviors among a sample of MSM. Participants responded to a brief survey five times a day for two weeks. Feasibility was measured by participant recruitment, enrollment, prompts received and answered, geotagged prompts, and technical interference with data collection. Acceptability was measured by ratings of enjoyment and willingness for future participation. Summaries of five behavioral measures from the brief survey were calculated. Among the 83 participants contacted, 67.5% (56) expressed interest, 98% (55) were scheduled, and 81.8% (45) were enrolled. Participants answered 78.3% (2,277) of prompts received and 87.7% (1,998) of answered prompts were geotagged. Overall, 70.5% (31) enjoyed participating and 91.1% (41) were willing to participate in the future. Among prompts answered, missingness was low for five behavioral measures (range 0.2% (4) to 0.7% (16)). Feasibility and acceptability were high and missingness was low on behavioral measures in this MSM study population. Most participants reported that they would participate again. Future work should focus on whether GEMA improves our understanding of syphilis and HIV transmission risk.

  相似文献   
24.
25.
Background: The prognostic value of p53 nuclear accumulation in gastric cancer is still unclear, as shown by the discordant results still reported in the literature. In this study, we evaluated the correlation between p53 accumulation and long-term survival of patients resected for intestinal and diffuse-type gastric cancer.Methods: Eighty-three patients with carcinoma of the intestinal type and 53 patients with carcinoma of the diffuse type were included in the study. Immunohistochemical staining of the paraffin sections was performed by using monoclonal antibody DO1; cases were considered positive when nuclear immunostaining was observed in 10% or more of the tumor cells. Prognostic significance of different variables was investigated by univariate and multivariate analysis.Results: p53 positivity was found in 51.8% of intestinal-type and 50.9% of diffuse-type cases. No significant correlation between the rate of p53 overexpression and age, sex, tumor location, tumor size, depth of invasion, lymph node involvement, distant metastases, and surgical radicality was found in the two groups of patients. A statistically significant difference in survival rate was observed between p53-negative and p53-positive cases in the intestinal type (P < .05), confirmed by multivariate analysis (P < .005; relative risk = 3.09). On the contrary, no correlation with survival was found in diffuse-type cases according to p53 overexpression.Conclusions: These results suggest that the immunohistochemical detection of p53 accumulation is a useful indicator of poor prognosis in the intestinal but not in the diffuse type of gastric cancer, and are indicative of distinct molecular pathways and pattern of progression in the two histotypes.  相似文献   
26.
27.
28.
29.
The aim of this study was to prepare and test an artificial corneal epithelium (reconstituted rabbit corneal epithelium, RRCE) exhibiting barrier characteristics and paracellular permeability similar to those of native rabbit cornea. The RRCE was obtained from a rabbit corneal epithelium (RCE) cell line grown for 8 days in submerged culture, then for 7 days in air-interface conditions on Snapwell polyester membranes. Permeation studies on the RRCE were carried out in comparison with rabbit excised corneas in vitro, using timolol maleate (TM) as the test drug, alone and in association with the following ocular permeation enhancers: benzalkonium chloride, ethylene-diaminetetraacetic acid sodium salt, polyethoxylated castor oil, polyoxyethylene stearyl ether, sodium deoxycholate, and escin. The integrity of the RRCE was assessed by measuring the transepithelial electrical resistance (TEER) during culture time and after every permeation experiment. When TM was tested alone, the permeation parameters (apparent permeability coefficient, lag time) obtained with the RRCE were similar to those of excised rabbit corneas. The artificial epithelium, however, was less sensitive than native cornea to the effect of permeation enhancers.  相似文献   
30.
Background Abdominal cystic formations in newborns are relatively common and often diagnostic suspicion arises in this regard even before birth as a result of ultrasound scans carried out during pregnancy. The aim of this study is to highlight the problems posed by the prenatal diagnosis of abdominal cysts in order to outline the most appropriate therapeutic approach in case of suspected ovarian cysts. Materials and methods Between January 2003 and January 2007, 57 women were enrolled in this study for a prenatal ultrasound (US) that revealed the presence of an echo-rare or echo-free area in the foetal abdomen. After birth all babies underwent blood tests and abdominal US scans in order to confirm or identify the nature of the cyst. If abdominal US could not show the nature of the cystic formation, magnetic resonance imaging with sedation was performed. When the radiological tests were not useful to identify the nature of the cysts and surgery was then necessary, surgical procedures were performed with laparoscopy. Results Ultrasounds were useful to identify the diameter of the cysts but not all their origins; also MRI confirmed the morphology and volume of the cysts, but could not give further details about their origin. Discussion Abdominal ultrasound and finally laparoscopy used to treat and remove the cysts were useful to monitor all simple abdominal cysts. MRI seemed not to be useful for the treatment of this condition, especially in the pediatric age when mild sedation is required.  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