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   7444篇
  免费   606篇
  国内免费   65篇
耳鼻咽喉   86篇
儿科学   117篇
妇产科学   137篇
基础医学   1101篇
口腔科学   105篇
临床医学   734篇
内科学   1812篇
皮肤病学   146篇
神经病学   603篇
特种医学   240篇
外科学   1028篇
综合类   153篇
一般理论   5篇
预防医学   536篇
眼科学   267篇
药学   396篇
中国医学   33篇
肿瘤学   616篇
  2023年   77篇
  2022年   159篇
  2021年   294篇
  2020年   192篇
  2019年   250篇
  2018年   315篇
  2017年   201篇
  2016年   239篇
  2015年   254篇
  2014年   317篇
  2013年   409篇
  2012年   567篇
  2011年   547篇
  2010年   335篇
  2009年   296篇
  2008年   433篇
  2007年   434篇
  2006年   365篇
  2005年   325篇
  2004年   287篇
  2003年   249篇
  2002年   178篇
  2001年   131篇
  2000年   101篇
  1999年   85篇
  1998年   43篇
  1997年   35篇
  1996年   47篇
  1995年   32篇
  1994年   33篇
  1992年   59篇
  1991年   58篇
  1990年   59篇
  1989年   52篇
  1988年   37篇
  1987年   41篇
  1986年   35篇
  1985年   45篇
  1984年   33篇
  1983年   38篇
  1982年   32篇
  1981年   33篇
  1980年   25篇
  1979年   35篇
  1978年   20篇
  1977年   18篇
  1976年   18篇
  1972年   17篇
  1937年   41篇
  1936年   38篇
排序方式: 共有8115条查询结果,搜索用时 15 毫秒
991.
Background: The addition of clonidine to peripheral nerve blocks is controversial in children. Objective: The aim of our study was to evaluate the effect of clonidine added to ropivacaine in pediatric axillary brachial plexus block (ABPB). Methods: Children aged 1–6 years, scheduled to undergo forearm or hand surgery, were recruited into this prospective, double‐blind controlled trial. Patients were randomly allocated to receive an ABPB either with ropivacaine 0.2% 0.4 ml·kg?1 plus saline in 1 ml (RS) or ropivacaine 0.2% 0.4 ml·kg?1 plus clonidine 1 μg·kg?1 in 1 ml (RC). Primary endpoints were quality of postoperative analgesia as assessed by pain scores and total 24‐h postoperative analgesia requirements. Secondary outcomes were time to first analgesia request and duration of motor blockade. Results: Sixty patients were recruited (n = 30 per group) into the study. Pain scores were comparable throughout the first 24 h between the two groups. Ten children in the (RS) and six in (RC) groups required supplementary analgesia during the first 24 h (P = 0.24). Children who required further analgesia did so after 288 ± 94 min in the (RS) and 437 ± 204 min in the (RC) group (P = 0.06). There was no difference in the duration of motor block [186 ± 71 and 154 ± 56 min, P = 0.12 for (RS) and (RC), respectively]. Conclusion: Ropivacaine (0.2% 0.4 ml·kg?1) for ABPB provides sufficient postoperative analgesia in children scheduled for forearm or hand surgery. The addition of clonidine to ABPB does not improve overall postoperative analgesia but may increase the time to first analgesia request.  相似文献   
992.
993.
994.
995.

Purpose

To investigate whether the universally accepted range of normal patellar height ratios derived from radiography for the Insall–Salvati (IS) and Blackburne–Peel (BP) methods could be similarly applied to both CT and MRI.

Materials and methods

Institutional review board approval was obtained with waiver of informed consent for this HIPPA-compliant study. A total of 45 knees in 42 patients (15 men, 27 women; age range 11 to 75?years, mean age 39?±?20?years) who underwent tri-modality (radiograph, CT, and MRI) examinations were selected. All patients had knee imaging obtained for a variety of reasons and measurements were performed by two independent readers who were blinded to each other’s measurements or the respective measurements derived from each of the methods. Paired t test was used to compare the mean values among the modalities. Inter-observer and inter-method agreements were assessed using intra-class correlation coefficients.

Results

Statistically significant, but small quantitative differences are noted between tri-modality patellar height ratios. For comparable results, the small addition of 0.13 and 0.10 are needed for the Insall–Salvati measurements on MRI and CT respectively, compared with radiographs. For the Blackburne–Peel ratio, an additional adjustment of 0.09 is needed between radiographs and MRI, but not between radiographs and CT. These adjustments are independent of gender. The interobserver reproducibility was excellent (ICC?≥?0.94) for both the Insall–Salvati and Blackburne–Peel methods for all modalities.

Conclusion

The results indicate that cut-off values for patella alta and baja derived from radiographs should not be directly transposed to CT and MRI; however, the adjustments are relatively minor. These measurements show excellent reproducibility for all modalities currently used for patellar height measurements.  相似文献   
996.
TO THE EDITOR: Nordmann et al. (1) raised concern over the global spread of carbapenemase-producing Enterobacteriaceae. In their article, they called attention to the oxacillinase-48 (OXA-48) type carbapenemases because bacteria that produce these enzymes do not have a distinctive antimicrobial drug susceptibility profile, and there is less awareness of this mechanism of carbapenem resistance. We report the recent isolation of bla(OXA-181)-positive Klebsiella pneumoniae from 2 patients from Bangladesh who were admitted to separate hospitals in Singapore within a short period of each other.  相似文献   
997.
An unusual case of saphenous neuropathy secondary to compression by a large hydatid cyst within the adductor longus muscle is reported. Solitary hydatid cyst(s) localized in the skeletal muscles occur rarely and often mimic soft tissue tumours. Presentation with signs of peripheral nerve compression by a hydatid cyst in an extremity is exceedingly rare. Diagnosis can be established by ultrasound, computerized tomography or magnetic resonance if clinically suspected. Clinical suspicion of hydatid origin of a solitary muscle cyst should be high especially in patients hailing from areas endemic for echinococcosis. Laboratory tests are usually unhelpful in such cases and needle biopsy carries the risk of anaphylactic shock and should therefore be avoided. Surgical removal of the unruptured cyst is the treatment of choice in cases of intramuscular hydatid cyst. In the present case, excision of the hydatid cyst was followed by complete clinical recovery. In the absence of systemic involvement, treatment with albendazole may be avoided.  相似文献   
998.
Conjunctival nodule is very rarely seen in patients with rheumatoid arthritis. Previously reported cases were associated with the use of methotrexate. Here, we report a conjunctival rheumatoid nodule without such prior treatment. A 49-year-old woman with seropositive rheumatoid arthritis, who was being treated only with oral steroids and hydroxychloroquine, developed diffuse anterior scleritis in the right eye. In addition, examination showed a focal raised yellow/tan conjunctival nodule. The nodule was within the bulbar conjunctiva with no attachments to the underlying tissue, which is different from nodular scleritis. The nodule was not tender on palpation. The patient underwent excisional biopsy of the nodule. Intraoperatively, the lesion was noted to be a firm nodule within substantia propria of the conjunctiva. Hematoxylin-eosin staining of the specimen revealed a central area of necrosis surrounded by palisades of histiocytes. Increased dosage of oral steroid after the biopsy resulted in resolution of the ocular symptoms and signs. In conclusion, rheumatoid nodules may be seen in the conjunctiva even without prior treatment with methotrexate. These nodules may show the severity of the underlying disease and the need for more aggressive treatment.  相似文献   
999.
1000.
Much of the variation in trace metal tissue concentrations in marine invertebrates has been attributed to the variety in individual organism size, age and sex. This study assessed the relationship between total mercury (Hg) concentrations in edible tissue, exoskeleton and viscera with length, weight and gender for 69 samples of crustaceans, Penaeus semisulcatus (n = 30), Thenus orientalis (n = 21) and Portunus pelagicus (n = 18) from the northern part of the Persian Gulf. Significant increase in the Hg level in muscle and viscera (r > 0.65, p < 0.01) with an increase in length and weight for all three species. No relationship was found between the Hg level in exoskeleton and length or weight. Significantly higher Hg levels (p < 0.01) were found in female P. semisulcatus than in males (muscle and viscera), but no gender differences were found for the other two species.  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