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   100267篇
  免费   6507篇
  国内免费   778篇
耳鼻咽喉   1115篇
儿科学   3006篇
妇产科学   2499篇
基础医学   13723篇
口腔科学   2164篇
临床医学   8220篇
内科学   22129篇
皮肤病学   2075篇
神经病学   9364篇
特种医学   3867篇
外国民族医学   23篇
外科学   14456篇
综合类   1679篇
一般理论   50篇
预防医学   5830篇
眼科学   1558篇
药学   8012篇
  3篇
中国医学   515篇
肿瘤学   7264篇
  2023年   416篇
  2022年   997篇
  2021年   1832篇
  2020年   1189篇
  2019年   1696篇
  2018年   2127篇
  2017年   1624篇
  2016年   1680篇
  2015年   1991篇
  2014年   2645篇
  2013年   3884篇
  2012年   5198篇
  2011年   5396篇
  2010年   3529篇
  2009年   3092篇
  2008年   4817篇
  2007年   5039篇
  2006年   4826篇
  2005年   4607篇
  2004年   4976篇
  2003年   4814篇
  2002年   4898篇
  2001年   3725篇
  2000年   3700篇
  1999年   3009篇
  1998年   1227篇
  1997年   958篇
  1996年   887篇
  1995年   846篇
  1994年   742篇
  1993年   713篇
  1992年   1811篇
  1991年   1773篇
  1990年   1509篇
  1989年   1464篇
  1988年   1332篇
  1987年   1206篇
  1986年   1191篇
  1985年   1051篇
  1984年   790篇
  1983年   713篇
  1982年   473篇
  1981年   414篇
  1979年   575篇
  1978年   427篇
  1975年   434篇
  1974年   489篇
  1973年   468篇
  1972年   424篇
  1971年   396篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The main objective of this study was to examine the psychosocial stress model developed by Taylor and Aspinwall with emotional exhaustion as the outcome variable. Respondents, 409 men and 346 women, who had a paid job for at least 20 hours per week, completed questionnaires concerning demographic variables, personality, temperament, work pressure, workload, perceived social support, appraisal, coping, and emotional exhaustion. Structural equation analyses provided only partial support for the validity of the model. First, on theoretical and statistical grounds, one more path linking external resources to social support was added. Second, contrary to expectations, coping styles did not predict emotional exhaustion. To conclude, when coping is measured retrospectively, it does not add to our understanding of emotional exhaustion. It is suggested that future studies should be longitudinal and include objective measures of stressors and psychosocial health outcomes in addition to self‐reports. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
92.
BACKGROUND: Neovascularisation at the sapheno-femoral junction (SFJ) ligation site in the groin may occur within one year after great saphenous vein (GSV) surgery. Several anatomical and prosthetic barrier techniques have been proposed to prevent this evolution. OBJECTIVE: A prospective study examined whether closing the cribriform fascia could reduce the incidence of postoperative neovascularisation in the groin. PATIENTS AND METHODS: Patients with primary varicose veins and incompetence at the level of the SFJ were included. After SFJ ligation in 235 limbs of 193 patients an anatomical barrier was constructed by closing the cribriform fascia. Postoperative duplex scanning was performed after 2 and 12 months. Results were compared with historical control groups in which either a silicone patch saphenoplasty or no barrier technique had been performed. RESULTS: After one year, 10 limbs had developed recurrent thigh varicose veins and duplex scan showed neovascularisation at the SFJ ligation site in 15 of 223 re-examined limbs (6.7%). This was comparable to the group of 191 limbs with silicone patch saphenoplasty (5.2%) (P=0.526) and superior to the group of 189 limbs without barrier (14.8%) (P<0.01). CONCLUSION: Interposition of an anatomical barrier by closing the cribriform fascia after SFJ ligation reduced ultrasound detected neovascularisation at the SFJ after one year. In primary varicose vein operations application of an anatomical barrier technique (without prosthetic patch) is an alternative option to prevent postoperative neovascularisation.  相似文献   
93.
Background: Postoperative pain mostly results from sensitization of afferent fibers at injury sites driving central sensitization. Recently, peripheral processes have gained attention as mechanisms of hyperalgesia, and prostaglandins are among highly sensitizing agents. To date, perioperative administration of a single local dose of nonsteroidal antiinflammatory drugs has shown inconclusive efficacy. Rather than a single bolus, the current study evaluates the postoperative analgesic effect of diclofenac continuous intrawound infusion after elective cesarean delivery.

Methods: Ninety-two parturients were randomly allocated to receive a 48-h continuous intrawound infusion with 240 ml containing 300 mg diclofenac, 0.2% ropivacaine, or saline. In the ropivacaine and saline groups, patients also received 75 mg intravenous diclofenac every 12 h for 48 h. Postoperative evaluation included intravenous morphine consumption by patient-controlled analgesia and visual analog pain scores. Punctate mechanical hyperalgesia surrounding the wound and presence of residual pain after 1 and 6 months were also assessed.

Results: Continuous diclofenac infusion significantly reduced postoperative morphine consumption (18 mg; 95% confidence interval, 12.7-22.2) in comparison with saline infusion and systemic diclofenac (38 mg; 95% confidence interval, 28.8-43.7) (P = 0.0009) without unique adverse effects. Postoperative analgesia produced by local diclofenac infusion was as effective as local ropivacaine infusion with systemic diclofenac.  相似文献   

94.
95.
The aim of the present study was to assess retrospectively the additional value of positron emission tomography (PET)/computed tomography (CT) in the detection of unexpected extrapulmonary lesions in the staging of patients with a malignant pulmonary lesion in comparison with CT and PET used alone. A total of 217 patients with a pathologically proven lung tumour underwent PET/CT. CT, PET and PET/CT were evaluated in the detection of extrapulmonary lesions. These abnormalities were compared with the final diagnosis obtained from the medical records and statistical analysis was carried out. In total, 108 lesions were clinically detected. PET/CT showed a sensitivity, specificity, positive and negative predictive values and accuracy of 100, 81, 71, 100 and 87%, respectively, for the detection of extrapulmonary lesions and 92, 98, 89, 98 and 97%, respectively, for the detection of malignant extrapulmonary lesions. PET/CT was significantly better than CT and PET used alone. Conventional staging work-up has a poor sensitivity in detecting second primary cancers or unexpected metastases. The detection of malignant extrapulmonary lesions is necessary for correct tumour staging. By combining both metabolic and anatomical information, positron emission tomography/computed tomography is able to depict more unexpected extrapulmonary lesions than computed tomography and positron emission tomography used alone, and positron emission tomography/computed tomography provides more additional information of malignancy or benignancy of lesions detected with one of the two imaging modalities alone.  相似文献   
96.
V-Y肌腱瓣修补术治疗陈旧性跟腱断裂   总被引:15,自引:2,他引:13  
目的 研究V—Y肌腱瓣修补术治疗陈旧性跟腱断裂的手术方法及结果。方法 对9例平均112d的陈旧性跟腱断裂患,采用小腿三头肌V—Y肌腱瓣修补术治疗修补缺损为3.2~6cm,平均4.6cm。结果 平均随访2年8个月,按Arner-Lindholm疗效评定标准评估,优7例(77.8%),良2例(22.2%),优良率为100%。结论 对于陈旧性跟腱断裂,小腿三头肌V—Y肌腱瓣修补术足一种方法简单、疗效满意的手术方法。  相似文献   
97.
We describe a modified keyhole laminoforaminotomy (LF) using anatomic landmarks on the posterior aspect of the cervical vertebral body to decompress the intervertebral foramen with minimal bone removal. Twenty-four procedures were performed at C3-4, C4-5, and C5-6; 12 at C6-7; and 3 at C7-Tl. Facets and laminae structures were identified based on relative surgical perspectives. Bony resection was limited as follows: 1) inferior limit; inferior border of the superior facet; 2) superior limit, superior border of the superior facet; 3) lateral limit, a vertical line linking the junction of the lamina-facet to the lateral end of the superior limit; and 4) lateral aspect of the dural sac. Fluoroscopy was used to confirm that the intervertebral space was reached. The amount of bony removal was quantified for the superior and inferior laminae and facets. The length of the exposed nerve root was measured. The intervertebral foramen was exposed and the intervertebral disc reached in all specimens. Fluoroscopy showed that the center of the exposure remained at the same height with the intervertebral space. The mean length of the nerve root was 4.6 mm; the mean percentage of bony resection was 21.8%, 7.5%, 11.3%, and 11.5% for the superior and inferior laminae and facets, respectively. Opening the intervertebral foramen posteriorly consistently exposed sufficient nerve root length and allowed access to the intervertebral disc. The technique offers the most direct and safest method of decompressing the intervertebral foramen while minimizing bony resection. This simple surgical procedure may help reduce postoperative morbidity.  相似文献   
98.
Cationic block copolymers spontaneously assemble via electrostatic interactions with DNA molecules in aqueous solution giving rise to micellar structures that protect the DNA from enzymatic degradation both in vitro and in vivo. In addition, we have previously shown that they are safe, not immunogenic and greatly increased antigen-specific CTL responses following six intramuscular inoculations of a very low dose (1 μg) of the vaccine DNA as compared to naked DNA. Nevertheless, they failed to elicit detectable humoral responses against the antigen. To gain further insight in the potential application of this technology, here we show that a shorter immunization protocol based on two DNA intramuscular inoculations of 1 μg of DNA delivered by these copolymers and a protein boost elicits in mice broad (both humoral and cellular) and long-lasting responses and increases the antigen-specific Th1-type T cell responses and CTLs as compared to priming with naked DNA. These results indicate that cationic block copolymers represent a promising adjuvant and delivery technology for DNA vaccination strategies aimed at combating intracellular pathogens.  相似文献   
99.

Background  

Total hip arthroplasty is a successful surgery, that fails at a rate of approximately 10% at ten years from surgery. Causes for failure are mainly aseptic loosening of one or both components partially due to wear of articular surfaces and partially to design. The present analysis aimed to identify risk factors and quantify their effects on aseptic failure.  相似文献   
100.
A survey was performed on the radiotherapy practice of malignant pleural mesothelioma in The Netherlands and Belgium in 2002. Thirty-eight out of 47 centres (81%) responded. Prophylactic radiotherapy to intervention sites is given by 32/38 (84%) centres, with all centres offering palliative radiation. For both prophylactic and palliative indications, all centres use hypo-fractionated schedules. The present study shows that in the radiotherapy community in The Netherlands and in Belgium, a de facto consensus exists that both prophylactic and symptomatic radiotherapy to intervention sites of malignant pleural mesothelioma are effective and that hypo-fractionated schedules should be used.  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