全文获取类型
收费全文 | 3493篇 |
免费 | 473篇 |
国内免费 | 32篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 42篇 |
妇产科学 | 185篇 |
基础医学 | 103篇 |
口腔科学 | 5篇 |
临床医学 | 2369篇 |
内科学 | 136篇 |
皮肤病学 | 17篇 |
神经病学 | 291篇 |
特种医学 | 214篇 |
外科学 | 185篇 |
综合类 | 270篇 |
现状与发展 | 1篇 |
预防医学 | 66篇 |
眼科学 | 8篇 |
药学 | 59篇 |
中国医学 | 11篇 |
肿瘤学 | 29篇 |
出版年
2023年 | 9篇 |
2022年 | 16篇 |
2021年 | 30篇 |
2020年 | 43篇 |
2019年 | 47篇 |
2018年 | 85篇 |
2017年 | 142篇 |
2016年 | 182篇 |
2015年 | 160篇 |
2014年 | 236篇 |
2013年 | 300篇 |
2012年 | 204篇 |
2011年 | 226篇 |
2010年 | 193篇 |
2009年 | 205篇 |
2008年 | 218篇 |
2007年 | 205篇 |
2006年 | 220篇 |
2005年 | 206篇 |
2004年 | 208篇 |
2003年 | 138篇 |
2002年 | 137篇 |
2001年 | 67篇 |
2000年 | 57篇 |
1999年 | 55篇 |
1998年 | 45篇 |
1997年 | 44篇 |
1996年 | 42篇 |
1995年 | 39篇 |
1994年 | 49篇 |
1993年 | 30篇 |
1992年 | 22篇 |
1991年 | 20篇 |
1990年 | 21篇 |
1989年 | 26篇 |
1988年 | 9篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 13篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 9篇 |
1980年 | 2篇 |
1979年 | 2篇 |
排序方式: 共有3998条查询结果,搜索用时 0 毫秒
21.
M.C. TEREK S. TAMSEL† S. AYGUL L. AKMAN S.V. IRER‡ I.M. ITIL & G. ALPER‡ 《International journal of gynecological cancer》2006,16(1):376-379
The aim of this study is to evaluate the changes in Doppler resistive index (RI) and plasma creatinine and magnesium concentrations after unilateral ureteral obstruction in a rabbit model. Fourteen adult female rabbits were used in this study. In seven rabbits, the left ureter was ligated with silk suture, and the control group was sham operated. Before surgery and on the second and seventh days after surgery, blood samples were obtained to measure plasma creatinine and magnesium concentrations. Doppler RIs of both kidneys were also measured before surgery and on the second and seventh days after the surgical procedure. With regard to magnesium levels, there was a significant within-subjects sessions difference [F(2, 20) = 15.21, P= 0.001] indicating a decrease through sessions. Magnesium concentrations decreased significantly at the postoperative second and seventh days compared to preoperative baseline levels (P= 0.003 and P= 0.001, respectively). Multifactorial analysis of variance was applied for each session separately with laterality, and groups as factors. The Doppler RI and the creatinine level did not show any significant differences or interactions for all sessions (P > 0.05). The decreasing plasma magnesium concentration after surgery may indicate ureteral injury; however, Doppler studies and creatinine levels may not be useful as well. 相似文献
22.
Balloon occlusion of the internal carotid artery in 40 cases of giant intracavernous aneurysm: technical aspects,cerebral monitoring,and results 总被引:13,自引:2,他引:11
V. Vazquez Añon A. Aymard Y. P. Gobin A. Casasco D. Rüffenacht M. H. Khayata E. Abizanda A. Redondo J. J. Merland 《Neuroradiology》1992,34(3):245-251
Summary We have studied the results of carotid occlusion in the treatment of giant intracavernous carotid artery (ICA) aneurysms in 40 patients. Clinical, angiographic, Doppler and cerebral blood flow (CBF) criteria for tolerance of occlusion are discussed. The patients had headaches (47.5%), cranial nerve compression (87.5%), decreased visual acuity (20%), ruptured aneurysm (15%) and 5% were asymptomatic. Balloon occlusion tests were performed under light sedation anaesthesia: a successful test required perfect clinical tolerance and adequate angiographic collateral circulation in arterial, parenchymatous, and venous phases. Additional criteria include xenon 133 CBF measurements, and transcranial Doppler sonography of the middle cerebral artery. According to these criteria, 5 patients did not tolerate test occlusion and required an extra-intracranial (EC-IC) bypass. Mean follow-up was 4.7 years. All patients were radiologically cured of their ancurysm, and in 35 the symptoms resolved, although 3 had persistent ocular motor nerve palsies, and in 4 visual defects were unchanged. Complications were 1 permanent and 3 transient neurological deficits. Balloon occlusion of the ICA is an effective, reliable form of treatment for intracavernous giant aneurysm and should replace surgical ligation of the cervical carotid artery. With CBF or Doppler monitoring, the risk of neurological deficit is diminished. EC-IC bypass prior to ICA occlusion is indicated if test occlusion is not tolerated. 相似文献
23.
Guerriero S Ajossa S Lai MP Risalvato A Paoletti AM Melis GB 《Human reproduction update》1999,5(5):515-529
This review describes the usefulness of colour Doppler energy (CDE) (or power Doppler) imaging to measure vascularization in the female reproductive tract. CDE imaging is characterized by an increased sensitivity to flow, and thus may be useful in low-flow states and when optimal Doppler angles cannot be obtained. In addition, longer segments of vessels and more individual vessels can be visualized with CDE imaging. The role of CDE imaging in the evaluation of stromal vasculature in normal and in polycystic ovaries is described, and the relationship between follicular vascularity and outcome following in-vitro fertilization are discussed, together with the findings obtained from the evaluation of thecal arteriole of corpus luteum in early pregnancy. The fundamental role of CDE imaging in differentiation among ovarian masses is also reviewed. We summarize the role of CDE imaging in pregnancy, and describe two new applications of three-dimensional power Doppler sonography and the use of ultrasound contrast media. In conclusion, CDE imaging can replace conventional colour Doppler when the information on the direction of flow is not useful. Moreover, the technique appears superior to others for describing microvascular architecture and determining the presence or absence of flow. 相似文献
24.
Transvaginal sonographic assessment of cervical length changes during triplet gestation 总被引:3,自引:0,他引:3
Maymon R Herman A Jauniaux E Frenkel J Ariely S Sherman D 《Human reproduction (Oxford, England)》2001,16(5):956-960
The current study aimed to evaluate the contribution of transvaginal sonography (TVS) for monitoring cervical changes during the second half of triplet gestation. Forty-five pregnant women with triplets pregnancies were prospectively scanned by TVS from approximately 26 weeks gestation and were longitudinally followed-up until delivery. Based on a receiver-operating curve it was found that a cervical length of 25 mm is the most accurate parameter (94% sensitivity and 45% specificity) for predicting premature delivery < or =33 gestational weeks. Thus, a single cervical length measurement of < or =25 mm at 26 weeks gestation correlated well with premature delivery at < or =33 weeks (chi(2); P = 0.002). Using the linear regression model, a mathematical equation [(Week of delivery = 27.4 + 1.6 x cervical length; R(2) = 0.46; P = 0.01)] for predicting the gestational age of delivery (dependent variable) was determined based on mid-gestation cervical measurements (predictors). In parturient women with triplet gestation, TVS assessment of the uterine cervix offers insight into the cervical status and provides valuable information for prenatal care. This includes both monitoring the cervical changes throughout third trimester as well as predicting the likelihood of premature delivery. 相似文献
25.
目的 探讨阑尾粘液囊肿 (AMC)的声像图表现 ,评价其临床意义 ;方法 回顾性分析了 7例AMC的声像图表现及超声与病理诊断的符合情况 ;结果 6例诊断正确 ,1例误诊 ,符合率 85 7% ,本组病理声像图的主要表现有①圆形或卵圆形边界清楚的超声暗区 ;②AMC最小 37mm× 30mm ,最大 5 8mm× 6 5mm ;③位于右下腹相当于阑尾的解剖部位 ;结论 作者初步经验表明超声检查为发现AMC的一种敏感和可靠的方法 ,有助于对是否需行手术治疗作出正确的判断 相似文献
26.
Transvaginal sonography and rectal endoscopic sonography for the assessment of pelvic endometriosis: a preliminary comparison 总被引:9,自引:0,他引:9
Bazot M Detchev R Cortez A Amouyal P Uzan S Daraï E 《Human reproduction (Oxford, England)》2003,18(8):1686-1692
BACKGROUND: Endometriosis and possible rectal involvement are difficult to assess by physical examination. Previous studies have shown the diagnostic value of magnetic resonance imaging and rectal endoscopic sonography (RES) in this setting, but not that of transvaginal sonography (TVS). The aims of this study were to compare the accuracy of TVS and RES for the diagnosis of pelvic endometriosis, and to compare the results with histological findings. PATIENTS AND METHODS: In a prospective study, 30 consecutive patients referred with clinical signs of endometriosis underwent TVS and RES; the images were interpreted blindly with regard to physical findings. RESULTS: Endometriosis was confirmed histologically in 28 (93%) of the 30 patients. Endometriomas were also present in 67% of cases. For the diagnosis of uterosacral endometriosis, the sensitivity, specificity, and positive and negative predictive values of TVS and RES were 75 and 75%, 83 and 67, 95 and 90%, and 45 and 40% respectively. For the diagnosis of rectosigmoid endometriosis, the sensitivity, specificity, and positive and negative predictive values of TVS and RES were 95 and 82%, 100 and 88%, 100 and 95%, and 89 and 64% respectively. CONCLUSION: Despite the large proportion of our patients who had intestinal endometriosis, representing a possible source of bias, our results suggest that TVS is as efficient as RES for detecting posterior pelvic endometriosis and should therefore be used as the first-line examination. 相似文献
27.
目的 :探讨癫发作间期脑血流变化对癫灶定侧的价值。方法 :4 7例癫病人发作间期行经颅多普勒超声脑血流速度测定 ,并与临床、脑电图定位和MRI/CT病灶对比分析。结果 :根据临床症状确定病灶侧的 19例病人中 ,病灶侧脑血流速度改变 (升高和降低 )的比率显著高于双侧脑血流速度对称者 ;在脑电图确定病灶侧的 2 4例病人中 ,病灶侧脑血流速度升高比率显著高于脑血流速度降低和双侧脑血流速度对称者 ;在MRI确定病灶侧的 13例病人中 ,病灶侧脑血流速度增快 7例 ,减慢 2例 ,双侧血流速度对称 4例。结论 :癫病人一侧脑血流速度增高 ,高度提示癫病灶侧。 相似文献
28.
羊水过少的B超诊断性试验分析 总被引:2,自引:0,他引:2
目的 探讨产前B超测定羊水平段诊断羊水过少的最佳界值。方法 对妊娠≥36周的孕妇进行B超测定羊水最大平段,剖宫产时实际测定羊水量,确定2.0cm、2.3cm、2.6cm、3.0cm、3.3cm、3.8cm等7个界点,分别计算其敏感性、特异性、阳性预测值和阴性预测值,对各界点的敏感性和(1-特异性)作受试者工作特性曲线。结果 当B超测定羊水平段界点为3.3cm,可获得较高的诊断敏感性和特异性,其值为80.56%和78.79%。结论 B超测定羊水平段界点值为3.3cm时,可产前诊断为羊水过少。 相似文献
29.
In the management of craniosynostosis, there is a need for quantitative assessment of treatment methods and outcome. Radiology and pressure studies are well documented, but so far little attention has been given to cerebral blood flow changes and their possible relevance. This paper reports our initial experience using transcranial Doppler sonography to calculate the cerebrovascular resistance and cerebral blood velocities in the major basal vessels before and after surgery for craniosynostosis. Ten patients were studied using the Scimed 2-MHz probe through the temporal and frontal windows of the skull. Measurements were taken under standard physiological conditions before, during and after surgery. Preliminary results suggest that this non-invasive technique may be helpful in predicting and assessing the outcome following surgery for craniosynostosis. 相似文献
30.
Wei-Jei Lee MD Jan-Show Chu MD Shyh-Jinn Houng MD Mei-Fu Chung BaN Shin-Ming Wang MD Dr. Kai-Mo Chen MD 《Annals of surgical oncology》1995,2(3):246-251
Background: Tumor growth and metastases require the development of new vessels (angiogenesis). Angiogenesis, assessed by microvessel count using immunocytochemical stain of endothelial cells, has been shown to predict metastases and correlate with early death. Recently developed color Doppler mapping can detect the “tumor flow signals” in breast cancer and help to distinguish it from benign lesions. The question is, does this tumor vascularization assessed by color Doppler mapping correlate with the angiogenesis assessed by immunocytochemistry? Methods: Eighty-four patients admitted for breast surgery were studied. The final diagnosis was made by pathology for 52 malignancies and 32 benign lesions. The color Doppler mapping of the breast lesion was made preoperatively. The following parameters were assessed: (a) vessel location (peripheral or central); (b) density of color Doppler signals; and (c) maximum systolic velocity. Tumor angiogenesis was assessed by microvessel count under light microscopy using the platelet/endothelial cell adhesion molecule antibodies (CD31) method. The correlation between maximum velocity and microvessel count of breast cancer was examined. The clinical significance of maximum flow velocity of breast cancer with various clinicopathologic factors was assessed. Results: Color signals were detected in 48 cases of 52 malignancies (92%). All tumors demonstrated signals at the periphery of the lesion but in only 13 (27%) were the signals detected within the tumor. Color signals were scored as + + or + + + in 44 (92%) patients. Pulsed wave blood flow was shown in all these 48 tumors, with maximum velocities varying from 4 to 36 cm/s. Among the 32 benign lesions, color signals were detected in 10 (31%) and all were peripheral and scored subjectively as +. Evaluation of these color Doppler mapping parameters shows no significant correlation with microvessel counts using CD31 monoclonal antibodies. However, there was a positive association (p<0.05) between nodal metastases and higher tumor flow velocity in T1 (<2 cm) breast tumors but not in larger tumors. Conclusion: Although the color Doppler mapping has been shown to be useful in distinguishing benign from malignant breast lesions, the intensity of signal and velocity of flow had no correlation with the extent of angiogenesis of breast cancer. The presence of high-flow tumor signal in early breast carcinoma is significantly associated with the presence of axillary lymph node metastases. 相似文献