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   55926篇
  免费   4995篇
  国内免费   3259篇
耳鼻咽喉   547篇
儿科学   537篇
妇产科学   652篇
基础医学   7147篇
口腔科学   1115篇
临床医学   6954篇
内科学   8724篇
皮肤病学   760篇
神经病学   3004篇
特种医学   2483篇
外国民族医学   37篇
外科学   6150篇
综合类   7855篇
现状与发展   7篇
一般理论   2篇
预防医学   3485篇
眼科学   1561篇
药学   5579篇
  49篇
中国医学   2740篇
肿瘤学   4792篇
  2024年   151篇
  2023年   796篇
  2022年   2208篇
  2021年   2918篇
  2020年   1969篇
  2019年   1817篇
  2018年   1966篇
  2017年   1693篇
  2016年   1799篇
  2015年   2616篇
  2014年   3234篇
  2013年   2925篇
  2012年   4669篇
  2011年   4752篇
  2010年   3025篇
  2009年   2476篇
  2008年   3200篇
  2007年   3072篇
  2006年   2854篇
  2005年   2609篇
  2004年   1879篇
  2003年   1719篇
  2002年   1507篇
  2001年   1214篇
  2000年   1235篇
  1999年   1174篇
  1998年   653篇
  1997年   693篇
  1996年   542篇
  1995年   454篇
  1994年   368篇
  1993年   255篇
  1992年   335篇
  1991年   250篇
  1990年   216篇
  1989年   189篇
  1988年   148篇
  1987年   134篇
  1986年   105篇
  1985年   90篇
  1984年   51篇
  1983年   51篇
  1982年   22篇
  1981年   24篇
  1980年   13篇
  1979年   23篇
  1978年   11篇
  1973年   11篇
  1971年   9篇
  1969年   10篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
目的:制备结合凝血酶原复合物(PCC)的阴离子脂膜微泡,评价微泡的理化性质。材料和方法:采用机械振荡直接连接法,分两组(于机械振荡之前或之后加入),制备结合PCC的阴离子脂膜微泡,观察并检测洗涤前后微泡的理化性质。结果:微泡与PCC的结合率及Ⅸ因子活性:两组间比较无明显差异(P>0.05),但洗涤后结合率由洗涤前的95%降为80%,活性由90%降为19%。结论:直接连接法可制备结合PCC的阴离子脂膜微泡,微泡与PCC结合率较高,且洗涤前能保持Ⅸ因子较高的活性。  相似文献   
82.
BACKGROUND: Epinephrine injected by an autoinjector in the anterolateral aspect of the thigh is the standard of care in the emergency self-treatment of anaphylaxis. In the United States, the autoinjector EpiPen is widely used for the self-treatment of anaphylaxis. OBJECTIVE: To investigate whether EpiPen autoinjector, with a needle length of 1.43 cm, is sufficient for intramuscular delivery of epinephrine in men and women. METHODS: The distance from skin to muscle in the anterolateral aspect of the thigh was measured in 50 men and 50 women who had undergone computed tomography of the thighs for other medical reasons. For each individual, body mass index (BMI; a measure of weight in kilograms divided by the square of height in meters) was also calculated, and the individuals were classified as underweight (BMI, < 18.5), normal (BMI, 18.5-24.9), overweight (BMI, 25.0-29.9), and obese (BMI, > or = 30.0) using standard definition. RESULTS: In the study participants the mean +/- SD distance from skin to muscle was 0.66 +/- 0.47 cm for men and 1.48 +/- 0.72 cm for women (P < .001). One man (obese at a BMI of 42.2) and 21 women (11 obese with a mean BMI of 35.2, 6 overweight with a mean BMI of 30.1, and 4 normal with a mean BMI of 24.5) had a greater distance from skin to muscle than the EpiPen needle length of 1.43 cm. CONCLUSION: The distance from skin to muscle for the anterolateral aspect of the thigh is higher in women compared with men. This difference suggests that EpiPen may not deliver epinephrine to the intramuscular tissue in many women.  相似文献   
83.
OBJECTIVE: To conduct a systematic review to gather the available evidence on the optimum timing of the radiotherapy in relation to autologous breast reconstruction. MATERIAL AND METHODS: The data was extracted from scientific databases, and a manual follow-up of references. The studies were selected which included at least 20 patients with any method of autologous breast reconstruction who were treated with adjuvant radiotherapy either before or after their reconstruction, and had addressed the effects of radiotherapy on the cosmetic outcome in their results. The principal outcome was cosmetic appearance. Secondary outcomes were immediate and delayed complications. RESULTS: We could not find any randomised controlled trial on this topic. Ten studies were included, most were retrospective, heterogeneous in terms of control groups, radiation doses, follow-up duration, and outcome measurements. Two studies included no control groups, and four studies compared the outcomes of patients with radiotherapy either before (n=3) or after (n=1) autologous breast reconstruction. The overall incidence of complications was increased in patients with radiotherapy in three out of these four studies. Only four studies directly compared the outcomes of patients who received radiotherapy before with patients who received radiotherapy after autologous breast reconstruction and two out of these reported worse outcomes associated with post-reconstruction radiotherapy. CONCLUSIONS: Despite the paucity of the published data, the current evidence suggests that the radiation has a deleterious effect on autologous flap reconstruction. Until better methods of radiation delivery can be devised to minimise the long term radiation sequelae in the irradiated tissue, delayed reconstruction seems to be a safe option in most of the cases. However, the findings from these studies should be interpreted with great caution before generalising from their results.  相似文献   
84.
85.
BACKGROUND & AIMS: The aim of this study was to assess the validity of frozen section analysis of endoscopic mucosal resection (EMR) specimens from Barrett's esophagus as compared with permanent sections for the detection of neoplasia. Frozen sections help to give immediate feedback for surgical procedures. It has not been determined whether EMR can be adequately interpreted by using frozen sections to aid endoscopists in completely resecting neoplastic lesions. METHODS: EMR specimens from Barrett's esophagus with high-grade dysplasia (HGD) and/or carcinoma were tested by frozen section. Pathologists evaluated EMR specimens for the depth of invasion as well as the appearance of clear margins of resection. The kappa statistic was calculated to assess the degree of agreement between the frozen section and permanent section diagnoses. RESULTS: Twenty-three consecutive patients underwent 30 EMRs with frozen section diagnosis. Frozen section revealed a carcinoma in 7 specimens (23%) and dysplasia in 20 (66%). Permanent sections found carcinoma in 8 specimens (26%), dysplasia in 19 specimens (63%), and normal or nondysplastic Barrett's esophagus in the remainder. The kappa statistic for the depth of invasion of EMR specimens was 0.93 (near perfect agreement). The kappa statistic for the margins of the EMR specimens was 0.80 (excellent agreement). CONCLUSIONS: This study indicated that frozen section analysis of esophageal EMR specimens is valid as compared with permanent section. This technique might allow rapid evaluation about the degree and depth of involvement of cancers. This allows physicians to make decisions regarding further therapy if margins are involved or decrease the use of EMR for histologically benign-appearing lesions.  相似文献   
86.
PURPOSES: Inhibition of cerulenin on the endogenous fatty acid synthetic activities of oral squamous cell carcinoma (OSCC) and normal oral mucosa was assayed. METHODS: Squamous cell carcinoma and normal oral mucosa were collected fresh from surgical specimens. The collected tissues were minced in RPMI 1640 and divided into 3 groups: cerulenin treated, dimethylsulfoxide treated, and control. The tissues were incubated in [1(2)-(14)C]acetic acid, sodium salt for the last 2.5 hours of the treatment at 37 degrees C in 5% CO(2). After labeling, total lipids were extracted and counted for (14)C by scintillation counting. RESULTS: Endogenous fatty acid synthetic activities of oral squamous cell caranoma in the cerulenin-treated group decreased by 19% at 1 hour, 64% at 2 hours, and 87% at 4 hours; remained nearly unchanged in the dimethylsulfoxide-treated group; and increased slightly in the control group. The oral mucosa tissues were only mildly affected by cerulenin in fatty acid synthesis. CONCLUSIONS: Cerulenin significantly inhibits fatty acid synthetic activity in squamous cell carcinoma and only mildly affected the oral mucosa, indicating that the fatty acid synthetic pathway may be exploited as a target for developing anticancer drugs.  相似文献   
87.
精神科护士的职业压力调查   总被引:5,自引:0,他引:5  
目的调查精神科护士在工作中面临的职业压力。方法采用问卷调查法,对贵州省贵阳市两所医院精神科61名护士与贵州省贵阳市多所医院173名护士的职业压力进行调查分析。结果精神科护士职业压力处于较高水平,其他科护士压力处于中等水平。结论建议从管理角度减轻精神科护士工作压力,并对精神科护士进行减轻工作压力的训练。  相似文献   
88.
OBJECTIVE: To evaluate the chemical composition and crystalline structures of Portland cement, gray ProRoot MTA (gray MTA), white ProRoot MTA (white MTA), and gray MTA-Angelus. STUDY DESIGN: X-ray diffraction analysis was used to identify and characterize crystalline phases, and energy dispersive x-ray spectrometer was used to determine the chemical composition of the test materials. Both powder form and set form were examined. RESULTS: The crystalline structure and chemical composition of gray and white MTA were similar except for the presence of iron in gray MTA. Both were composed mainly of bismuth oxide and calcium silicate oxide. Portland cement was composed mainly of calcium silicate oxide and did not contain bismuth oxide. Gray MTA-Angelus had a lower content of bismuth oxide than ProRoot MTA. There were no noticeable differences in the chemical composition and crystalline structures between the powder and set forms of any of the material tested. CONCLUSION: Portland cement differed from the MTA by the absence of bismuth ions and presence of potassium ions. Gray MTA contained a significant amount of iron when compared with white MTA. In addition, gray MTA-Angelus had a lower content of bismuth oxide than ProRoot MTA.  相似文献   
89.
目的探讨用游离自体腹白线片修补急性十二指肠溃疡穿孔的应用价值。方法从2006年1月至2006年7月对13例用自体腹白线片修补急性十二指肠溃疡穿孔的病人的临床资料和随访情况进行回顾性分析,其中2例穿孔大于2cm2,平均手术时间60分钟,平均失血量20ml,平均住院天数9±1天。结果游离自体腹白线片修补急性十二指肠溃疡穿孔13例均痊愈出院。随访15天至6个月,无手术并发症。结论本方法操作较简单、安全、效果好,其适应症广,是一种可行的新方法。  相似文献   
90.
垂体腺瘤是发生于垂体前叶的良性肿瘤,约占中枢神经系统肿瘤的10%-20%,而无功能微腺瘤占到成人尸检的23%左右。生理上根据免疫组化将垂体腺瘤按功能分为有激素分泌活性腺瘤(functioning pituitary adenoma,FPA)和非激素分泌活性腺瘤(non—functioning pituitary adenoma,NFPA)两大类。[第一段]  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