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   1480篇
  免费   57篇
  国内免费   8篇
耳鼻咽喉   15篇
儿科学   15篇
妇产科学   6篇
基础医学   137篇
口腔科学   34篇
临床医学   116篇
内科学   448篇
皮肤病学   57篇
神经病学   173篇
特种医学   44篇
外科学   175篇
综合类   3篇
预防医学   27篇
眼科学   71篇
药学   59篇
中国医学   1篇
肿瘤学   164篇
  2023年   7篇
  2022年   14篇
  2021年   28篇
  2020年   13篇
  2019年   30篇
  2018年   26篇
  2017年   24篇
  2016年   33篇
  2015年   26篇
  2014年   45篇
  2013年   58篇
  2012年   81篇
  2011年   102篇
  2010年   62篇
  2009年   52篇
  2008年   72篇
  2007年   135篇
  2006年   97篇
  2005年   107篇
  2004年   96篇
  2003年   92篇
  2002年   113篇
  2001年   28篇
  2000年   26篇
  1999年   22篇
  1998年   25篇
  1997年   19篇
  1996年   13篇
  1995年   9篇
  1994年   7篇
  1993年   9篇
  1992年   14篇
  1991年   5篇
  1990年   8篇
  1989年   3篇
  1988年   4篇
  1987年   4篇
  1986年   6篇
  1985年   3篇
  1984年   3篇
  1983年   2篇
  1982年   4篇
  1981年   3篇
  1980年   3篇
  1979年   4篇
  1978年   3篇
  1977年   1篇
  1974年   1篇
  1970年   1篇
  1963年   1篇
排序方式: 共有1545条查询结果,搜索用时 15 毫秒
41.
A 43-year-old Japanese woman presented hypertension, hypokalemia and typical Cushingoid signs. Autonomous secretion of both aldosterone and cortisol was shown. Abdominal computed tomography demonstrated a single tumor in the right adrenal gland, which established the diagnosis of combined primary aldosteronism and Cushing's syndrome. The resected tumor was a golden yellow-colored adenoma (diameter 4.3 cm) which expressed P450(aldo) and P450(11beta), causing oversecretion of both hormones from this adenoma. After tumor resection, overproduction of both hormones disappeared and she developed adrenal insufficiency, suggesting the strong suppression of normal adrenal function. This case was complicated by Hashimoto's thyroiditis.  相似文献   
42.
Aims: We evaluated the relationship between the ratios of eicosapentaenoic acid and arachidonic acid (EPA/AA), docosahexaenoic acid (DHA)/AA, and delta-5 desaturase activity (D5D) and atherogenic lipid profiles (ALP) and coronary atherosclerosis.Methods: Polyunsaturated fatty acids (PUFA) and ALP were assessed in 436 men with the first episode of acute coronary syndrome (ACS) not take any lipid-lowering drugs. D5D was estimated as the ratio of AA to dihomogamma-linolenic acid (DGLA). These biomarkers were compared between the lower and higher levels of EPA/AA (0.41) or DHA/AA (0.93) according to the levels in Japanese general population. The thrombolysis in myocardial infarction flow (TIMI) grade of the culprit coronary artery was visually estimated during the initial angiography.Results: Approximately 70% of patients had low EPA/AA or DHA/AA. Serum levels of LDL-cholesterol, apolipoprotein B (apoB), and remnant lipoprotein cholesterol (RL-C) were significantly higher in the low EPA/AA or DHA/AA groups, while those of triglycerides and malondialdehyde-modified LDL (MDA-LDL) were significantly higher in the low EPA/AA group alone. The levels of EPA, EPA/AA, DHA/AA, and HbA1c increased and those of DGLA and apoA1 decreased with increasing number of stenotic vessels. Patients with three stenotic coronary vessels or TIMI grade ≥ 1 had significantly higher EPA levels compared with the others. The levels of LDL-cholesterol, non-HDL-cholesterol, triglycerides, small dense LDL-cholesterol, RL-C, MDA-LDL, apoB, and apoE decreased progressively and those of EPA, DHA, EPA/AA and HDL-cholesterol increased as D5D increased.Conclusions: The EPA/AA is a superior risk marker than DHA/AA in term of correlation with ALP in ACS patients.  相似文献   
43.
44.
Background and Aims: Colorectal laterally spreading tumors (LST) > 20 mm are usually treated by endoscopic submucosal dissection (ESD) or endoscopic mucosal resection (EMR). Endoscopic piecemeal mucosal resection (EPMR) is sometimes required. The aim of our study was to compare the outcomes of ESD and EMR, including EPMR, for such LST. Methods: A total of 269 consecutive patients with a colorectal LST > 20 mm were treated endoscopically at our hospital from April 2006 to December 2009. We retrospectively evaluated the complications and local recurrence rates associated with ESD, hybrid ESD (ESD with EMR), EMR, and EPMR. Results: ESD and EMR were performed successfully for 89 and 178 LST, respectively: 61 by ESD; 28 by hybrid ESD; 70 by EMR; and 108 by EPMR. Between‐group differences in perforation rates were not significant. Local recurrence rates in cases with curative resection were as follows: 0% (0/56) in ESD; 0% (0/27) in hybrid ESD; 1.4% (1/69) in EMR; and 12.1% (13/107) in EPMR; that is, significantly higher in EPMR. No metastasis was seen at follow up. The recurrence rate for EPMR yielding ≥ three pieces was significantly high (P < 0.001). All 14 local recurrent lesions were adenomas that were cured endoscopically. Conclusions: As for safety, ESD/hybrid ESD is equivalent to EMR/EPMR. ESD/hybrid ESD is a feasible technique for en bloc resection and showed no local recurrence. Although local recurrences associated with EMR/EPMR were seen, which were conducted based on our indication criteria, all local recurrences could obtain complete cure by additional endoscopic treatment.  相似文献   
45.
The sites and numbers of submental perforator vessels were examined using a Doppler probe in 21 volunteers. The subcutaneous vascular network from each perforator was studied in three cases of dissection of upper-neck lymph nodes among the volunteers. A perforator from the submental vessels was noted in all 21 volunteers: a single perforator in 13 cases, and double perforators in eight. The main perforator, which had some subdermal branches, was located 31.8 (8.3) mm in front of the facial artery that was palpated at the mandible. Five patients who presented with skin defects on the cheek and the chin had the submental perforator flap reconstructed, excluding the platysma muscle. All flaps covered the wounds. The submental perforator flap was useful for reconstructing skin defects on the cheek and the chin, because the site of the submental perforator was stable and raising the flap was easy, and the colour and texture matches were acceptable.  相似文献   
46.
Abstract

To clarify the topographical relationship between peri-Rolandic lesions and the central sulcus, we carried out presurgical functional mapping by using magnetoencephalography (MEG), functional magnetic resonance imaging (f-MRI), and motor evoked potentials (MEPs) on 5 patients. The sensory cortex was identified by somatosensory evoked magnetic fields using MEG (magnetic source imaging (MSI)). The motor area of the hand region was identified using f-MRI, during a hand squeezing task. In addition, transcranial magnetic stimulation localized the hand motor area on the scalp, which was mapped onto the MRI. In all cases, the sensory cortical vein or the lack of any functional activation in the area of peri-lesional edema. MEPs were also unable to localize the entire motor strip. Therefore, at present, MSI is considered to be the most reliable method to localize peri-Rolandic lesions. [Neurol Res 1995; 17: 361-367] cortical vein or the lack of any functional activation in the area of peri-lesional edema. MEPs were also unable to localize the entire motor strip. Therefore, at present, MSI is considered to be the most reliable method to localize peri-Rolandic lesions. [Neurol Res 1995; 17: 361-367]  相似文献   
47.
48.
49.

Purpose

The goal of this study was to compare the accuracy and cranial facet joint violation rates between percutaneous pedicle screw placements using conventional fluoroscopy and intraoperative 3-D CT (O-arm) computer navigation.

Methods

We reviewed 194 pedicle screw of 28 consecutive patients who underwent minimally invasive lumbar or thoracic spinal stabilization. The accuracy of screw placement was evaluated according to two criteria published by Neo et al. and Upendra et al. Facet joint violation was evaluated according to the classification described by Babu et al.

Results

Upon Neo grading, CFT group had 19.4 % (14/72) pedicle breach rate and CT-IGN group had a 5.7 % (7/122) pedicle breach rate (p < 0.005). The same sets of screws were also assessed using the outcome-based classification established by Upendra. There were no screw caused neurovascular injuries (type 3 = 0) in both groups. The results showed that 87.5 % (63/72) screws had acceptable placements (type I) and 12.5 % (9/72) had unacceptable placements (type II) in CFT group. In contrast, 94.3 % (115/122) screw had acceptable placements (type I) and only 5.7 % (7/122) had unacceptable placements (type II) in CT-IGN group. Additionally, CFT group had a significantly higher facet joint violation rate of 30.5 % (11/36) than CT-IGN group that had a 3.8 % (3/79) violation rate (p < 0.005).

Conclusion

This study indicated the use of intraoperative CT imaging (O-arm) navigation in PPS placement have very beneficial implications for MIS.
  相似文献   
50.
This study examined whether the mechanical characteristics of the cochlea could influence individual variation in the ability to use temporal fine structure (TFS) information. Cochlear mechanical functioning was evaluated by swept-tone evoked otoacoustic emissions (OAEs), which are thought to comprise linear reflection by micromechanical impedance perturbations, such as spatial variations in the number or geometry of outer hair cells, on the basilar membrane (BM). Low-rate (2 Hz) frequency modulation detection limens (FMDLs) were measured for carrier frequency of 1000 Hz and interaural phase difference (IPD) thresholds as indices of TFS sensitivity and high-rate (16 Hz) FMDLs and amplitude modulation detection limens (AMDLs) as indices of sensitivity to non-TFS cues. Significant correlations were found among low-rate FMDLs, low-rate AMDLs, and IPD thresholds (R = 0.47–0.59). A principal component analysis was used to show a common factor that could account for 81.1, 74.1, and 62.9 % of the variance in low-rate FMDLs, low-rate AMDLs, and IPD thresholds, respectively. An OAE feature, specifically a characteristic dip around 2–2.5 kHz in OAE spectra, showed a significant correlation with the common factor (R = 0.54). High-rate FMDLs and AMDLs were correlated with each other (R = 0.56) but not with the other measures. The results can be interpreted as indicating that (1) the low-rate AMDLs, as well as the IPD thresholds and low-rate FMDLs, depend on the use of TFS information coded in neural phase locking and (2) the use of TFS information is influenced by a particular aspect of cochlear mechanics, such as mechanical irregularity along the BM.  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