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   1838篇
  免费   204篇
  国内免费   25篇
耳鼻咽喉   21篇
儿科学   61篇
妇产科学   25篇
基础医学   145篇
口腔科学   43篇
临床医学   234篇
内科学   414篇
皮肤病学   104篇
神经病学   87篇
特种医学   139篇
外科学   364篇
综合类   101篇
现状与发展   30篇
预防医学   67篇
眼科学   16篇
药学   53篇
中国医学   3篇
肿瘤学   160篇
  2024年   14篇
  2023年   182篇
  2022年   16篇
  2021年   30篇
  2020年   65篇
  2019年   27篇
  2018年   63篇
  2017年   50篇
  2016年   42篇
  2015年   61篇
  2014年   92篇
  2013年   75篇
  2012年   48篇
  2011年   53篇
  2010年   88篇
  2009年   103篇
  2008年   65篇
  2007年   104篇
  2006年   63篇
  2005年   57篇
  2004年   51篇
  2003年   40篇
  2002年   54篇
  2001年   36篇
  2000年   31篇
  1999年   40篇
  1998年   35篇
  1997年   56篇
  1996年   44篇
  1995年   37篇
  1994年   32篇
  1993年   35篇
  1992年   14篇
  1991年   15篇
  1990年   16篇
  1989年   29篇
  1988年   26篇
  1987年   20篇
  1986年   12篇
  1985年   17篇
  1984年   9篇
  1982年   12篇
  1981年   11篇
  1980年   12篇
  1977年   7篇
  1976年   15篇
  1975年   12篇
  1974年   7篇
  1973年   7篇
  1971年   7篇
排序方式: 共有2067条查询结果,搜索用时 15 毫秒
111.
CHENGGANG YI  MD    YONG PAN  MD    YAN ZHEN  MM    LINXI ZHANG  MD    XUDONG ZHANG  MD    MAOGUO SHU  MD    YAN HAN  MD    SHUZHONG GUO  MD 《Dermatologic surgery》2006,32(12):1437-1443
BACKGROUND: A recent discovery showed that endothelial progenitor cells (EPCs) could augment collateral vessel growth to ischemic tissues. OBJECTIVE: The objective was to demonstrate the effects of EPCs on the vasculogenesis and survival of free transplanted fat tissues in nude mice. METHODS: EPCs from human donors were cultured in vitro for 7 days. Human fat tissues were injected subcutaneously into the scalps of 20 6-week-old nude male mice. EPCs stained with CM-DiI were mixed with the transplanted fat tissues and injected into the mice. EBM-2 medium was used as control group. The animals were euthanized 15 weeks after the procedure. Graft volume were measured, and histologic evaluation was performed. The central part of fat tissues was histologically evaluated 15 weeks after the fat injection. RESULTS: The survival volume of the experimental group was significantly greater than that of the control group (p< .05). Less cyst formation and fibrosis was obtained in the experimental group. Histologic evaluation of the central part of fat tissues 15 weeks after the fat injection showed that capillary densities increased markedly in the experimental group mice. CONCLUSION: The results indicate that EPCs have the ability to enhance the survival and the quality of the transplanted fat tissues.  相似文献   
112.
Division of the splenic vein was performed in 29 patients who underwent pancreatoduodenectomy to achieve lymph node dissection and neural resection around the superior mesenteric artery. The basic protocol for the splenic vein reconstruction to reduce congestion of the spleen and stomach is as follows. When the inferior mesenteric vein (IMV) drained into the splenic vein, the confluence was preserved without reconstruction of the splenic vein. When the IMV drained into the superior mesenteric vein (SMV) or the splenomesenteric angle, the division of the IMV and spleno-IMV anastomosis were performed. In postoperative venography, nine patients showed downward flow (from the splenic vein to the IMV) and three patients showed upward flow (from the IMV to the splenic vein). Postoperative computed tomography scans showed venous dilatation and splenomegaly in the upward flow group; there were no patients in the downward flow group. In selected patients, splenic vein reconstruction is necessary to reduce congestion of the spleen and stomach. When the flow is downward, spleno-IMV flow should be preserved. When the flow is upward, spleno-SMV anastomosis is necessary instead of spleno-IMV anastomosis.  相似文献   
113.
Background Psoriatic lesions may involve nearly all sites of the body. Involvement of the genital skin is frequently classified as part of intertriginous psoriasis without special awareness and treatment for this presentation of the disease. Gaining knowledge about the frequency of the involvement of genital skin in these patients will improve the overall care for patients with psoriasis. Objectives We studied the prevalence of genital psoriasis in the Netherlands and epidemiological characteristics of this specific presentation of the disease. Furthermore, we studied the relation between flexural and genital psoriasis. Patients/Methods A self‐administered questionnaire was sent to all 5300 members of the Dutch Psoriasis Society. Sociodemographic patient characteristics and disease‐related data (such as localization of psoriatic lesions, involvement of the genitalia, age at onset of genital psoriasis and severity of genital psoriatic lesions) were collected and analysed. Results A response rate of 37% was achieved. Almost 46% of the responding patients with psoriasis, that is 16.5% of all potential responders (n = 5300), report genital involvement at some time during the course of their disease. The genitalia can become affected at any age. Many patients with current genital involvement (38%) do not have the flexural skin affected. Conclusions A large part of patients with psoriasis suffer from genital psoriasis, which was not associated with flexural involvement in at least one third of them. More attention to the genital region is required in the current standard treatment of both male and female psoriatic patients at any age.  相似文献   
114.
Background: Patients with hepatocellular carcinoma (HCC) sometimes suffer from obscure gastrointestinal bleeding. Portal hypertension (PH), common in cirrhosis, induces esophagogastric varices. Because of the location, PH also may influence mucosal abnormalities in the small intestine. The objective of this study is to estimate the prevalence of small intestinal mucosal abnormalities in HCC patients using capsule endoscopy (CE). Patients and Methods: We prospectively conducted CE in HCC patients, and analyzed the findings in relation to hepatic function, the number and size of HCC tumor and findings obtained by conventional endoscopy. Results: Thirty‐six patients (aged 66.7 ± 7.5 years, 29 men) underwent CE. Abnormal findings in the small bowel were found in 16 patients (44%), angioectasias in eight patients (22%), erosions in five (14%), varices in four (11%), polyps in four (11%), and submucosal tumor in one (3%). The patients with angioectasia had a larger spleen index than the no abnormal lesions group (85.4 ± 15.8 vs 59.0 ± 24.4, P = 0.02). The former group had been more frequently treated for esophageal varices endoscopically (62% vs 15%, P = 0.02). Large HCC nodules seemed more common in the patients with angioectasia than subjects without abnormal lesions (38% vs 5%, P = 0.06). Small intestinal varices also seemed to have a positive association with large HCC. During the follow up after CE, one patient with small intestinal polyps suffered from obscure gastrointestinal bleeding. Conclusions: CE revealed that HCC patients frequently have small intestinal mucosal lesions. In particular, small intestinal angioectasia, which may cause obscure gastrointestinal bleeding, seems to be associated with portal hypertension.  相似文献   
115.
Aim: To investigate mothers’ perceptions of breastfeeding and influences from their social network. Methods: A cross‐sectional survey was carried out in Mangochi district, Malawi where questionnaire data from 157 rural and 192 semi‐urban mother–infant pairs were obtained. Results: The proportion of mothers who thought that exclusive breastfeeding should last for 6 months and those who reported to have actually exclusively breastfed were 40.1% and 7.5% respectively. Of those who reported practising exclusive breastfeeding for 6 months, 77.5% stated that exclusive breastfeeding should last for 6 months. This opinion was independently associated with giving birth in a Baby‐Friendly facility, OR = 5.22; 95% CI (1.92–14.16). Among the mothers who thought that exclusive breastfeeding should last for less than 6 months, 43.9% reported having been influenced in their opinion by health workers. Infant crying was the most common (62.4%) reason for stopping exclusive breastfeeding. Conclusion: The findings illustrate the positive impact health workers can have, as well as the need to raise awareness of the benefits of exclusive breastfeeding among both health workers and mothers. Furthermore, continued counselling of mothers on how to deal with stressful infant behaviour such as crying may assist to prolong exclusive breastfeeding.  相似文献   
116.

Background  

Accurate measurement of physical activity is a pre-requisite for monitoring population health and for evaluating effective interventions. The International Physical Activity Questionnaire (IPAQ) is used as a comparable and standardised self-report measure of habitual physical activity of populations from different countries and socio-cultural contexts. The IPAQ has been modified to produce a New Zealand physical activity questionnaire (NZPAQ). The aim of this study was to validate the IPAQ and NZPAQ against doubly labelled water (DLW). Method: Total energy expenditure (TEE) was measured over a 15-day period using DLW. Activity-related energy expenditure (AEE) was estimated by subtracting the energy expenditure from resting metabolic rate and thermic effect of feeding from TEE. The IPAQ (long form) and NZPAQ (short form) were completed at the end of each 7-day period. Activity-related energy expenditure (IPAQAEE and NZPAQAEE) was calculated from each questionnaire and compared to DLWAEE.  相似文献   
117.
Breast feeding and dietary habits were studied prospectively in a cohort of children under the age of five years in a rural Somali community. The median duration of breast feeding was 19.5 months. However, all the children also received cow's milk by cup from the first day of life and onwards. Energy supplements (mainly sugar and oil) as well as additional water were given daily from early infancy. Staples, protein-rich foods (beans and meat), vegetables and fruits were usually introduced when the children reached the age of 12-18 months. There was a seasonal variation with the lowest intake of protein-rich and vitamin-rich foods during the rains in May to June. Thus, there was a complete absence of exclusive breast feeding. Energy-reinforced cow's milk and human milk dominated the diet up to the age of one year. Staples were mixed with oil and supplemented with milk, thereby leading to a much higher energy density in the complementary food than is usually the case in African communities.  相似文献   
118.
119.
Ornithine carbamoyl transferase (OCT) activity and other liver function tests were studied in a total of 50 patients of clinical malaria and 15 controls. They were grouped as group I (positive for malarial parasite on peripheral blood smear, n=18), group II (negative for malarial parasite on peripheral blood smear (PBS) but responded to antimalarials, n=17) and group III (peripheral blood smear negative and did not respond to antimalarial therapy, n=15). The mean OCT levels were significantly raised in group I (6.79 ± 1.84 IU/L, p value = 0.006) and group II (5.0 ± 1.15 IU/L, p value = 0.014) as compared to controls (2.5 ± 1.13 IU/L) and returned to normal after treatment In contrast, group III had normal levels except in a case of kala azar and septicemia where OCT levels were high and increased further on treatment. Taking PBS positivity as a gold standard of diagnostic criteria, OCT had a sensitivity of 83% and specificity of 86% with a high positive predictive value of 88% as compared to ALT which had a lower sensitivity of 55% and specificity of 80%. The clinical response rate in PBS negative cases of fever having high OCT level was 83% as compared to 35% in cases with normal OCT level, making OCT a good surrogate marker of malaria. OCT levels could also be of prognostic significance as 2 cases of cerebral malaria had high OCT levels of 11.1 UAL and 10.7 IU/L, respectively.Key Words: Malaria, Ornithine carbamoyl transferase  相似文献   
120.
Carcinosarcoma of the ovary is a very rare and highly malignant neoplasm that accounts for less than 1% of ovarian neoplasms. Survival of patients with advanced stage cancer is poor and the best treatment is not clear. We report the case of a 60-year-old woman who had Stage IV advanced heterogeneous ovarian carcinosarcoma with lung and liver metastases. The lesions were considered surgically incurable, so she was placed on neoadjuvant chemotherapy of combination CPT-11 (60 mg/m2, day 1, 15) and CDDP (60 mg/m2, day 1). Tumor markers of CA125 and LDH decreased remarkably to the normal level after 3 and 4 courses of chemotherapy, respectively. After 7 courses of chemotherapy, the ovarian tumor was obviously reduced, and the lung and liver metastases had disappeared. The patient was then able to undergo surgery. The current case suggests that combination CPT-11 and CDDP is effective against advanced ovarian carcinosarcoma.  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