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   1182篇
  免费   64篇
  国内免费   15篇
耳鼻咽喉   36篇
儿科学   54篇
妇产科学   84篇
基础医学   99篇
口腔科学   16篇
临床医学   87篇
内科学   376篇
皮肤病学   24篇
神经病学   54篇
特种医学   34篇
外科学   231篇
综合类   18篇
预防医学   19篇
眼科学   55篇
药学   47篇
肿瘤学   27篇
  2023年   3篇
  2022年   15篇
  2021年   24篇
  2020年   10篇
  2019年   28篇
  2018年   32篇
  2017年   32篇
  2016年   45篇
  2015年   55篇
  2014年   69篇
  2013年   97篇
  2012年   84篇
  2011年   90篇
  2010年   50篇
  2009年   64篇
  2008年   99篇
  2007年   107篇
  2006年   73篇
  2005年   77篇
  2004年   50篇
  2003年   40篇
  2002年   39篇
  2001年   13篇
  2000年   6篇
  1999年   5篇
  1998年   4篇
  1997年   9篇
  1996年   3篇
  1995年   3篇
  1994年   5篇
  1993年   5篇
  1992年   10篇
  1991年   10篇
  1990年   2篇
  1989年   1篇
  1988年   2篇
排序方式: 共有1261条查询结果,搜索用时 15 毫秒
81.
82.
We report a case of a sewing needle, presumably originating from the transverse colon or the ligament of Treitz, that migrated to the greater omentum. A 24-year-old woman was referred to our clinic with a complaint of abdominal pain which was exacerbated by breathing or any physical activity. Abdominal plain x-ray showed a needle in the left upper abdominal area. Abdominal computed tomography (CT) and contrast enhanced x-ray studies was unable to reveal whether the needle was in the colonic lumen. Virtual colonoscopy examination demonstrated that the foreign body was not in the lumen. The foreign body was removed from the patient's greater omentum in a fluoroscopy- guided laparoscopic surgery. An accurate and rapid diagnosis of a perforation in the gastrointestinal tract as the result of an ingested foreign body is difficult in the absence of peritonitis or abscess formation. In such cases, the virtual colonoscopy is useful if there is uncertainty whether the foreign body is in the lumen. Perioperative fluoroscopy can be useful to overcome the lack of tactile discrimination in laparoscopy, in patients who have been scheduled for surgery who have no signs of the localization of the foreign body (such as abscess or solid organ migration).  相似文献   
83.
This paper presents 4 consecutive cases using negative-pressure dressings (VAC) to bolster skin grafts in male genital reconstruction. In this series reconstruction followed 1 case of tumor ablation and 3 cases of debridement of abscesses or Fornier's gangrene. The VAC was applied circumferentially to the penis to secure skin grafts either directly to the penile shaft or to facilitate skin grafting to the scrotum. Graft areas ranged from 75 to 250 cm. All cases resulted in successful genital wound coverage; minor complications are described. Three practical points are brought forth. First, the VAC facilitates skin grafting to the complex contour of male genitalia. Second, the VAC can be applied circumferentially to the penis without the need for perfusion monitoring or fears of avascular necrosis. Third, with the use of the VAC, bolster use can likely be discontinued as early as 72 hours with good graft adherence and survival.  相似文献   
84.
Spinal neurenteric cysts are rare congenital lesions of endodermal origin that lead to spinal cord compression or tethering. These cysts are usually lined by mucus-secreting epithelium resembling that of the gastrointestinal tract. A 31-year-old man presented with low back and bilateral limb pain of three-year duration. Magnetic resonance imaging (MRI) revealed an intradural extramedullary heterogeneous mass lesion at L4 - L5 disc level causing severe compression and displacement of terminal portion of conus medullaris to the left side. Additionally, tethered cord, syringohydromyelia and spina bifida were present. He had also polysyndactyly on the left foot. The patient underwent laminoplasty and partial excision of the lesion through a posterior approach. Neurosurgical exploration revealed a large intradural, extramedullary solid lesion with cystic component, compressing the spinal cord. Histopathology confirmed a neurenteric cyst with mucin-producing cuboidal or columnar epithelium lining the cystic cavity. Clinical suspicion is important for an early diagnosis, and their early preplanned surgical removal should be the goal of treatment, which leads to a better outcome. This case is reported in view of rare congenital abnormality in an adult with peculiar presentation.  相似文献   
85.
OBJECTIVES: To determine the incidence of chromosome abnormalities among couples for whom intracytoplasmic sperm injection (ICSI) treatment was indicated and fetuses conceived through the ICSI procedure. METHODS: All cytogenetic results were evaluated retrospectively. Patients undergoing ICSI (n = 508) were classified according to the referring indications as: (1) males with severe infertility (87 azoospermia and 34 oligoasthenoteratozoospermia, OAT), (2) prior to ICSI (56 males and 61 females), and (3) following an unsuccessful ICSI procedure (132 males and 138 females). Fetuses conceived through ICSI (n = 475) were also classified into 4 groups according to the additional risk factors for chromosome abnormalities: ICSI (n = 185), ICSI + advanced maternal age (AMA, n = 215), ICSI + positive triple test result (TT, n = 50), and ICSI + abnormal ultrasound findings (USG, n = 25). RESULTS: An abnormal karyotype was found in 31.03% of males with azoospermia and 14.71% of males with OAT, in 3.57% of males and 1.64% of females in the group prior to ICSI, and in 5.30 and 5.07%, respectively, in the group following unsuccessful ICSI treatment. Gonosomal aneuploidies were predominant in males with azoospermia and autosomal rearrangements in males with OAT, while low-level sex chromosome mosaicism was found in females. The overall frequency of chromosome abnormalities in fetuses was 4.42% and varied in the different groups from 1.62% in ICSI, 2.79% in ICSI + AMA, 10.0% in ICSI + TT to 28.0% in ICSI + USG. The frequencies of the different types of chromosome abnormalities were as follows: balanced 1.05%, unbalanced 3.37%, familial 0.84%, de novo 3.37%, autosomal 3.58%, gonosomal 0.84%, numerical 1.89%, structural abnormalities 2.53%, and mosaicism 1.26%. CONCLUSION: Our results indicate that cytogenetic investigations of the ICSI parents and fetuses are essential for the families, genetic counselors and also reproductive centers. In fetal karyotyping, de novo structural chromosome abnormalities and mosaicism should be taken into consideration.  相似文献   
86.
PURPOSE: To evaluate whether repeated courses of high-dose methylprednisolone (HDMP) affect the lumbar spine bone mineral density (BMD) in children with chronic idiopathic thrombocytopenic purpura (ITP). MATERIALS AND METHODS: This study included 24 patients with chronic ITP and 149 healthy controls. The patients were allocated into three groups according to the number of HDMP courses (30 mg/kg per day as a single dose for 7 days); group 1 (10 patients), group 2 (9 patients), and group 3 (5 patients) had received less than 5, 6-10, and more than 10 courses, respectively. Lumbar spine BMD and body composition were measured using dual energy X-ray absorptiometry of lumbar spine (L2-L4), and volumetric bone mineral density (vBMD) values were calculated and compared with the controls. The z score of the vBMD was also calculated and compared in the patients of each other groups. Serum markers of the bone turnover were measured to exclude other factors that could effect BMD. RESULTS: The vBMD values of the patients, corrected BMDs for age, were significantly lower than the values of controls (P = 0.018). It was significantly lower in group 3 than groups 1 and 2 (P = 0.005 and P = 0.006, respectively), but there was no statistically significant difference between groups 1 and 2 (P = 0.87). The vBMD z scores were significantly lower in group 3 than in groups 1 and 2 (P = 0.003 and P = 0.004, respectively), and also in group 2 than in group 1 (P = 0.034). There were a weak negative correlation between the cumulative dose of HDMP and vBMD (r = -0.39, P = 0.054), and strong negative correlation between the cumulative dose of HDMP and vBMD z score (r = -0.63, P = 0.001). CONCLUSION: Children with chronic ITP are at risk for decreased BMD because of the repeated courses of HDMP; especially more than 2100 mg of cumulative dose. We therefore recommend that BMD should be monitored in patients with chronic ITP who received repeated courses of HDMP.  相似文献   
87.
OBJECTIVE: To assess and compare various simple insulin sensitivity and beta-cell function indices in lean, hirsute, young women. DESIGN: Prospective study. SETTING: Departments of endocrinology and metabolism at a university and a state hospital. PATIENT(S): Seventy-one hirsute young women were classified as hyperandrogenemic or normoandrogenemic. MAIN OUTCOME MEASURE(S): Insulin sensitivity and beta-cell function indices derived from a single sample and an oral glucose tolerance test (OGTT). RESULT(S): Lean hyperandrogenemic hirsute women have insulin resistance and increased beta-cell function. The most sensitive indices of insulin resistance were total and 1-hour and 2-hour post-challenge insulin levels during OGTT. When a cut-off value of 3.2 or greater for homeostasis model assessment of insulin resistance (HOMA-IR) was accepted, 46% of hyperandrogenemic women and 30% of normoandrogenemic women were insulin resistant. Fasting insulin level was best correlated with the fasting insulin resistance index, HOMA-IR, and Quicky index. The HOMA-IR was best correlated with fasting insulin level and the hepatic insulin sensitivity index (ISI(HOMA)). CONCLUSION(S): Insulin levels based on OGTT are the most useful index of insulin resistance and beta-cell function index in hirsute women. The HOMA-IR may be a proposed global test for insulin resistance; it correlated well with both OGTT-derived insulin resistance and beta-cell function indices and with global insulin resistance indices derived from a single sample (such as ISI (HOMA), Quicky index, FIRI(-1), fasting Belfiore index, and glucose/insulin ratio).  相似文献   
88.
 The purpose of this study was to investigate the associations of tooth loss with skeletal bone mass, years since menopause, educational level, current smoking status, dietary calcium intake, and number of pregnancies in postmenopausal osteoporotic women in Turkey. The study population consisted of 1171 postmenopausal women aged 40–86 years (mean age, 61.19 ± 7.28 years). A detailed history was obtained from all women, including relevant lifestyle parameters, risk factors, and measurements of weight and height. Women were separated into three groups according to the number of teeth remaining as group 1 (edentulous, 457 women), group 2 (10 or fewer teeth, 232 women), and group 3 (more than 10 teeth remaining, 482 women). There was no significant difference among the three groups in mean age and menopausal age (P < 0.05). Body mass index of group 1 was significantly higher than that of group 2 (P < 0.01). Educational level was significantly different between three groups: groups 1 and 2 (P < 0.001), groups 1 and 3 (P < 0.0001), and groups 2 and 3 (P < 0.001). Educational level was lowest in group 1 and highest in group 3. Despite a low ratio of cigarette smoking in general, a smoking habit was most prevalent in group 3 and least in group 2. The ratio of women receiving adequate calcium was significantly lower in group 1 than in other groups (P < 0.001); mean calcium intake was similar in all groups. The number of pregnancies was significantly higher in group 1 than in other groups (P < 0.001). Lumbar bone mineral density (BMD) of group 1 was significantly lower than that of groups 2 and 3 (P < 0.001). Although no significant difference was found between groups 1 and 3, femoral neck BMD of group 2 was less than in others, and differences between groups 1 and 2 and between groups 2 and 3 (P < 0.001) were significant. Lumbar bone mineral content (BMC) of group 1 was significantly lower than that of groups 2 and 3 (P < 0.001), and lumbar BMC in group 2 was significantly higher than in group 3 (P < 0.05). Femoral neck BMC in group 1 was significantly higher than in groups 2 and 3 (P < 0.001). In conclusion, lumbar BMD and BMC in the edentulous group were significantly lower, whereas femoral neck BMD and BMC were significantly higher in edentulous group compared with the others. Our findings indicated that improvement in lifestyle factors and nutritional strategies for the treatment and prevention of osteoporosis may have additional benefit in reducing tooth loss. Received: February 18, 2002 / Accepted: June 21, 2002 Offprint requests to: A. Gur  相似文献   
89.
We studied bone mineral metabolism changes complicated by acute gastroenteritis in a clinical acute metabolic acidosis milieu where we observed hypercalcemia, hypercalciuria, and elevated urinary hydroxyproline excretion. Serum magnesium and plasma osteocalcin, alkaline phosphatase, and IGF-1 levels were decreased. No significant changes in serum inorganic phosphate and plasma PTH, calcitonin, or 25-hydroxy vitamin D3 levels were detected. All abnormalities disappeared with the correction of acidosis. Observed hypercalcemia seems to be the result of increased calcium efflux from bone due to metabolic acidosis-induced catabolism of type 1 collagen and decreased osteoblastic activity. This study provides data regarding acute metabolic acidosis-induced changes in noninvasive parameters of bone modeling, assessed for the first time in humans.  相似文献   
90.
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