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   10565篇
  免费   421篇
  国内免费   124篇
耳鼻咽喉   41篇
儿科学   207篇
妇产科学   119篇
基础医学   1270篇
口腔科学   138篇
临床医学   984篇
内科学   2549篇
皮肤病学   210篇
神经病学   778篇
特种医学   727篇
外科学   1769篇
综合类   52篇
一般理论   5篇
预防医学   757篇
眼科学   195篇
药学   652篇
中国医学   17篇
肿瘤学   640篇
  2024年   26篇
  2023年   65篇
  2022年   118篇
  2021年   281篇
  2020年   171篇
  2019年   261篇
  2018年   320篇
  2017年   191篇
  2016年   194篇
  2015年   264篇
  2014年   331篇
  2013年   481篇
  2012年   774篇
  2011年   724篇
  2010年   499篇
  2009年   475篇
  2008年   651篇
  2007年   736篇
  2006年   576篇
  2005年   641篇
  2004年   541篇
  2003年   480篇
  2002年   509篇
  2001年   86篇
  2000年   79篇
  1999年   101篇
  1998年   151篇
  1997年   141篇
  1996年   166篇
  1995年   123篇
  1994年   108篇
  1993年   82篇
  1992年   52篇
  1991年   58篇
  1990年   43篇
  1989年   69篇
  1988年   57篇
  1987年   56篇
  1986年   58篇
  1985年   66篇
  1984年   29篇
  1983年   22篇
  1982年   30篇
  1981年   17篇
  1980年   20篇
  1979年   17篇
  1978年   19篇
  1977年   13篇
  1976年   17篇
  1975年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
A 49-year-old woman presented with acute abdominal pain in the right iliac fossa in our emergency department. Pain was abrupt in onset and severely colicky in nature. Abnormal laboratory values included a C-reactive protein of 75 mg/L and a CA-125 of 70.3 U/mL. White blood cell count was normal. Abdominal computed tomography (CT) scan revealed an inhomogeneous mass of 9.5 x 3.5 x 5.5 cm in diameter close to the appendix vermiformis and the sigmoid colon. Because of the clinical symptoms of an acute abdomen an explorative laparotomy was performed. Intraoperatively a pedunculated tumor beginning at the serosa of the sigmoid colon was found. The appendix was unremarkable. The macroscopic aspect as well as the backtable incision of the tumor was suspicious of an intraperitoneal liposarcoma. Rapid section and histopathologic examination revealed necrotic fat tissue without any malignancy. The patient was discharged from the hospital 7 days after the operation with normal laboratory parameters and without further complication. When epiploic appendagitis is evident as a big tumor mass in addition to clinical symptoms of an acute abdomen and elevated tumor markers, surgical exploration is mandatory.  相似文献   
72.
73.
Pothuaud L  Carceller P  Hans D 《BONE》2008,42(4):775-787
X-ray imaging remains a very cost-effective technique, with many applications in both medical and material science. However, the physical process of X-ray imaging transforms (e.g. projects) the 3-dimensional (3D) microarchitecture of the object or tissue being studied into a complex 2D grey-level texture. The 3D/2D projection process continues to be a difficult mathematical problem, and neither demonstrations nor well-established correlations have positioned 2D texture analysis-based measurement as a valid indirect evaluation of 3D microarchitecture. The trabecular bone score (TBS) is a new grey-level texture measurement which utilizes experimental variograms of 2D projection images. The aim of the present study was to determine the level of correlation between the 3D characteristics of trabecular bone microarchitecture, as evaluated using muCT reconstruction, and TBS, as evaluated using 2D projection images derived directly from 3D muCT reconstruction. Analyses were performed using sets of human cadaver bone samples from different anatomical sites (lumbar spine, femoral neck, and distal radius). Significant correlations were established via standard multiple regression analysis, and via the use of a generic mathematical 3D/2D relationship. In both instances, the correlations established a significant relationship between TBS and two 3D characteristics of bone microarchitecture: bone volume fraction and mean bone thickness. In particular, it appears that TBS permits to accurately differentiate between two 3D microarchitectures that exhibit the same amount of bone, but different trabecular characteristics. These results demonstrate the existence of a robust and generic relationship, taking into consideration a simplified model of a 2D projection image. Ultimately, this may lead to using TBS measurements directly on DXA images obtained in routine clinical practice.  相似文献   
74.
75.
BACKGROUND/OBJECTIVE: Prone carts are used for mobility by individuals with spinal cord injury in whom seated mobility (wheelchair) is contraindicated due to ischial or sacral pressure ulcers. Currently available prone carts are uncomfortable, subjecting the user to neck and shoulder strain, and make social interaction and performing activities of daily living difficult. A better design of prone carts is needed. In addition, standing devices have shown some medical benefits. The objective was to design and evaluate an improved prone cart that facilitates standing. DESIGN: Engineering development project with user feedback through questionnaire. Users selected by convenience sampling. METHODS: A marketing survey was performed of nurse managers of spinal cord injury units. Then 2 prototype carts were designed and built. These carts are able to tilt up to 45 degrees and have a joystick-controlled motor for propulsion and other design features, including a workspace storage shelf and rearview mirrors. The carts were evaluated by both patients and caregivers at 2 Veteran's Administration hospitals. OUTCOME MEASURES: Questionnaire of subjects, both patients and caregivers, who used the cart. FINDINGS: Both patients and caregivers liked the carts and the ability to assume a nonhorizontal body angle. The major complaint about the cart was that it seemed too long when it came to making turns. CONCLUSION: This prone cart design is an improvement over the standard, flat variety. However, further design changes will be necessary. This study provided valuable information that will be useful in the next-generation prone cart design project.  相似文献   
76.
77.
78.

Purpose

Though surgical decompression is today a common option for treatment of cervical spondylotic myelopathy (CSM), little is known about the exact postoperative early neurological recovery course. The purpose of this study was to analyze the functional recovery, its dynamics, its intensity and its pattern, in the early postoperative period after surgical decompression for CSM.

Methods

A prospective non-controlled observational study was performed from March 2006 to July 2008, and included consecutive patients with CSM who underwent surgical decompression. Functional assessments were done before the operation, at 1 month, 6, 12, 18 and 24 months after surgery using three tests: the Japanese Orthopaedic Association (JOA) test, the nine-hole peg test (9HPT) and the Crockard walking test.

Results

Sixty-seven patients were included (mean age of 61 years). The global JOA score improved after surgery, reaching statistical significance at 1 month (from 11.5 ± 2.6 to 13.6 ± 2.0 points, p = 0.0078), then settling to a plateau till the end of follow-up at 24 months (12.7 ± 2.6 points). The 9HPT and the Crockard test did not show any significant improvement after surgery.

Conclusions

Neurological recovery after surgical decompression has been proved to be very fast during the first month, but stabilizes afterwards. The JOA score is the best assessment to reveal neurological improvement in the early recovery course.  相似文献   
79.

Background

Resection of lung metastases (LM) from colorectal cancer (CRC) is increasingly performed with a curative intent. It is currently not possible to identify those CRC patients who may benefit the most from this surgical strategy. The aim of this study was to perform a systematic review of risk factors for survival after lung metastasectomy for CRC.

Methods

We performed a meta-analysis of series published between 2000 and 2011, which focused on surgical management of LM from CRC and included more than 40 patients each. Pooled hazard ratios (HR) were calculated by using random effects model for parameters considered as potential prognostic factors.

Results

Twenty-five studies including a total of 2925 patients were considered in this analysis. Four parameters were associated with poor survival: (1) a short disease-free interval between primary tumor resection and development of LM (HR 1.59, 95 % confidence interval [CI] 1.27–1.98); (2) multiple LM (HR 2.04, 95 % CI 1.72–2.41); (3) positive hilar and/or mediastinal lymph nodes (HR 1.65, 95 % CI 1.35–2.02); and (4) elevated prethoracotomy carcinoembryonic antigen (HR 1.91, 95 % CI 1.57–2.32). By comparison, a history of resected liver metastases (HR 1.22, 95 % CI 0.91–1.64) did not achieve statistical significance.

Conclusions

Clinical variables associated with prolonged survival after surgery for LM in CRC patients include prolonged disease-free interval between primary tumor and metastatic spread, normal prethoracotomy carcinoembryonic antigen, absence of thoracic node involvement, and a single pulmonary lesion.  相似文献   
80.
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