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   3284篇
  免费   200篇
  国内免费   22篇
耳鼻咽喉   33篇
儿科学   103篇
妇产科学   74篇
基础医学   482篇
口腔科学   36篇
临床医学   352篇
内科学   685篇
皮肤病学   23篇
神经病学   232篇
特种医学   177篇
外科学   620篇
综合类   29篇
现状与发展   1篇
预防医学   196篇
眼科学   51篇
药学   179篇
中国医学   5篇
肿瘤学   228篇
  2023年   16篇
  2022年   30篇
  2021年   69篇
  2020年   47篇
  2019年   74篇
  2018年   80篇
  2017年   63篇
  2016年   66篇
  2015年   94篇
  2014年   134篇
  2013年   169篇
  2012年   271篇
  2011年   262篇
  2010年   142篇
  2009年   142篇
  2008年   229篇
  2007年   228篇
  2006年   199篇
  2005年   217篇
  2004年   190篇
  2003年   167篇
  2002年   182篇
  2001年   28篇
  2000年   21篇
  1999年   18篇
  1998年   34篇
  1997年   16篇
  1996年   8篇
  1995年   20篇
  1994年   21篇
  1993年   16篇
  1992年   19篇
  1991年   13篇
  1990年   7篇
  1989年   11篇
  1988年   11篇
  1987年   9篇
  1986年   11篇
  1985年   12篇
  1984年   10篇
  1983年   9篇
  1982年   16篇
  1981年   11篇
  1980年   15篇
  1979年   10篇
  1978年   10篇
  1977年   8篇
  1976年   7篇
  1975年   6篇
  1974年   6篇
排序方式: 共有3506条查询结果,搜索用时 15 毫秒
41.
Autologous blood donation in total knee arthroplasties is not necessary   总被引:2,自引:0,他引:2  
BACKGROUND: This study intends to prove the hypothesis that preoperative autologous blood donation in total knee arthroplasties (TKA) is dispensable. PATIENTS AND METHODS: The study comprises a prospective analysis of 81 consecutive TKA without preoperative autologous blood donation (AB-donation). Guidelines for blood retransfusion were used. Surgery, as well as the pre- and postoperative procedures were identical for each patient. In the analysis of the data, the consecutive TKAs were divided into patients who were eligible for preoperative autologous blood donation (group 1, n = 46) and those with relevant risk factors not permitting preoperative autologous blood donation (group 2, n = 35). RESULTS: None of the patients in group 1 needed a blood transfusion. 14 of 35 patients in group 2 needed an allogenic blood transfusion. INTERPRETATION: Total knee arthroplasty can be managed without preoperative AB-donation if it is performed using a tourniquet, if a postoperative collection and direct retransfusion system is used for the wound blood, and if the transfusion algorithm is defined according to compulsory and practical guidelines.  相似文献   
42.
While most BK virus infections are asymptomatic, immunosuppression has been associated with BK virus reactivation and impaired graft function or ureteric ulceration in renal transplant patients and hemorrhagic cystitis in bone marrow transplant patients. Oncogenicity is also postulated and this is the first report of a child with a carcinoma of the donor renal pelvis following BK virus allograft nephropathy. Removal of the primary tumor and cessation of immunosuppression led to regression of secondary tumors and a return to health.  相似文献   
43.
Ethanol consumption and spontaneous (essential) hypertension are important fetal and maternal risk factors. Alone, they contribute to embryopathy (fetal alcohol syndrome) or maternal organ pathology and fetal loss in hypertensive pregnancies. Combined, the effects of ethanol consumption on the progress of a hypertensive pregnancy have not been adequately investigated. In the present study, groups of O-A strain genetic hypertensive (SHR: groups 1 and 2) and Wistar-Kyoto normotensive (WKY: groups 3 and 4) pregnant rats were given 20 ml/kg of distilled water by gavage to serve as controls [groups 1 (SHR) and 3 (WKY)] or 3.2 g/kg of ethanol [groups 2 (SHR) and 4 (WKY)] from days 6 to 15 of gestation. During acclimation, hypertension developed in SHR rats (WKY pressures were 105 to 114 mm Hg; SHR pressures were 137 to 148 mm Hg). From day 6 to 15 of gestation, ethanol-consuming rats (groups 2 and 4) had higher arterial pressures than controls (groups 1 and 3). Pregnant SHR rats given ethanol did not experience a prebirthing hypotension. On gestation day 20, most offspring (84%, group 2; 86%, group 4) of alcoholic dams were dead or malformed. Intrauterine growth retardation occurred in group 4. Hydrocephalus, microphthalmia, and mild hydronephrosis and hydroureter were common in live offspring of group 2 dams. Hydronephrosis and hydroureter were increased in group 4 pups. Variant cranial ossification was noted in group 2 and 4 pups. These preliminary data suggest an altered hypertensive response during pregnancy in alcohol-consuming rats and confirm the embryopathic effects of relatively high levels of ethanol consumed during the critical period of organogenesis in two additional strains of rats.  相似文献   
44.
Although the sex steroid hormone testosterone is integrally involved in the development of language processing, ethical considerations mostly limit investigations to single hormone administrations. To circumvent this issue we assessed the influence of continuous high‐dose hormone application in adult female‐to‐male transsexuals. Subjects underwent magnetic resonance imaging before and after 4 weeks of testosterone treatment, with each scan including structural, diffusion weighted and functional imaging. Voxel‐based morphometry analysis showed decreased gray matter volume with increasing levels of bioavailable testosterone exclusively in Broca's and Wernicke's areas. Particularly, this may link known sex differences in language performance to the influence of testosterone on relevant brain regions. Using probabilistic tractography, we further observed that longitudinal changes in testosterone negatively predicted changes in mean diffusivity of the corresponding structural connection passing through the extreme capsule. Considering a related increase in myelin staining in rodents, this potentially reflects a strengthening of the fiber tract particularly involved in language comprehension. Finally, functional images at resting‐state were evaluated, showing increased functional connectivity between the two brain regions with increasing testosterone levels. These findings suggest testosterone‐dependent neuroplastic adaptations in adulthood within language‐specific brain regions and connections. Importantly, deteriorations in gray matter volume seem to be compensated by enhancement of corresponding structural and functional connectivity. Hum Brain Mapp 37:1738–1748, 2016. © 2016 Wiley Periodicals, Inc .  相似文献   
45.

Objective

This observational pilot study investigated effects of aromatherapy massage in paediatric burn patients.

Methods

The setting was a 17 beds level I burn unit in Cape Town, South Africa. Between January and October 2009 heart rates and respiratory rates of patients who underwent aromatherapy massage sessions were read before and after the sessions. Primary outcomes were decline in heart rates and respiratory rates, a sign of relaxation. Behavioural responses (sleep/awake state, facial expression, body posture) were documented as secondary outcomes.

Results

A convenience sample of 71 paediatric burn patients (median age 3 years) underwent a total of 126 massage sessions. Mean heart rate decreased significantly from 118 (SD 20) to 109 (SD 21), t = 9.8, p < 0.001. Mean respiratory rate decreased significantly from 34 (SD 8) to 30 (SD 8), t = 10.2, p < 0.001. Most massage sessions (92.8%) elicited positive behaviour to the massage, e.g. the child fell asleep, calmed or asked to continue. Nine patients (7.2%) with a median age of 15 months who underwent a single massage session did not show positive behaviour but cried, wriggled or were distressed.

Conclusions

Aromatherapy massage seems to be a helpful nonpharmacological approach to reduce hospitalized paediatric burn patients’ distress. Future studies with better research designs and validated outcome measures should confirm our findings.  相似文献   
46.
AIM: To define the magnetic resonance imaging (MRI) parameters differentiating urethral hypermobility (UH) and intrinsic sphincter deficiency (ISD) in women with stress urinary incontinence (SUI).METHODS: The static and dynamic MR images of 21 patients with SUI were correlated to urodynamic (UD) findings and compared to those of 10 continent controls. For the assessment of the urethra and integrity of the urethral support structures, we applied the high-resolution endocavitary MRI, such as intraurethral MRI, endovaginal or endorectal MRI. For the functional imaging of the urethral support, we performed dynamic MRI with the pelvic phased array coil. We assessed the following MRI parameters in both the patient and the volunteer groups: (1) urethral angle; (2) bladder neck descent; (3) status of the periurethral ligaments, (4) vaginal shape; (5) urethral sphincter integrity, length and muscle thickness at mid urethra; (6) bladder neck funneling; (7) status of the puborectalis muscle; (8) pubo-vaginal distance. UDs parameters were assessed in the patient study group as follows: (1) urethral mobility angle on Q-tip test; (2) Valsalva leak point pressure (VLPP) measured at 250 cc bladder volume; and (3) maximum urethral closure pressure (MUCP). The UH type of SUI was defined with the Q-tip test angle over 30 degrees, and VLPP pressure over 60 cm H2O. The ISD incontinence was defined with MUCP pressure below 20 cm H2O, and VLPP pressure less or equal to 60 cm H2O. We considered the associations between the MRI and clinical data and UDs using a variety of statistical tools to include linear regression, multivariate logistic regression and receiver operating characteristic (ROC) analysis. All statistical analyses were performed using STATA version 9.0 (StataCorp LP, College Station, TX).RESULTS: In the incontinent group, 52% have history of vaginal delivery trauma as compared to none in control group (P < 0.001). There was no difference between the continent volunteers and incontinent patients in body habitus as assessed by the body mass index. Pubovaginal distance and periurethral ligament disruption are significantly associated with incontinence; periurethral ligament symmetricity reduces the odds of incontinence by 87%. Bladder neck funneling and length of the suprapubic urethral sphincter are significantly associated with the type of incontinence on UDs; funneling reduced the odds of pure UH by almost 95%; increasing suprapubic urethral sphincter length at rest is highly associated with UH. Both MRI variables result in a predictive model for UDs diagnosis (area under the ROC = 0.944).CONCLUSION: MRI may play an important role in assessing the contribution of hypermobility and sphincteric dysfunction to the SUI in women when considering treatment options.  相似文献   
47.
With a randomized clinical trial, we compared the incidence and severity of heterotopic ossification in cohorts of patients who have undergone either surface replacement arthroplasty or total hip arthroplasty at a minimum follow-up of 1 year. Surface replacement arthroplasty group had a significantly higher rate of severe heterotopic ossification (Brooker grades 3-4) than the total hip arthroplasty group, 12.6% (13/103) vs 2.1% (2/97) respectively (P = .02). Grade 4 heterotopic ossification was observed (4.9%, 5/103) exclusively in the surface replacement arthroplasty group. Patients with severe heterotopic ossification had significantly inferior functional outcome scores. Surgeons offering surface replacement must be aware of this risk and use meticulous surgical technique and consider routine prophylaxis against heterotopic ossification.  相似文献   
48.
The purpose of this study was to evaluate the value of complex hemodialysis access procedures among patients with central venous obstruction who were running out of access sites. Between September 2002 and December 2003 we performed a total of 640 new hemodialysis access procedures in 3 renal units. Ten of these patients presented central vein stenosis or obstruction and were not suitable for peritoneal dialysis. Each of the 10 patients had 3 or 4 previous failed access procedures and numerous infected central lines and their dialysis catheters were not functioning adequately. Nine patients presented with a severely stenosed or occluded superior vena cava and 1 had both subclavian veins occluded. Three patients were diabetics, 2 were obese and 6 had hypertension. We performed 12 procedures on these 10 patients. Saphenous veins were used 6 times, twice as a loop to the femoral artery and 4 times as a transposition to the popliteal artery above the knee. Femoral vein transposition to the popliteal artery was carried out in 2 cases. We performed 3 axillary artery to popliteal vein polytetrafluoroethylene (PTFE) bypasses, 1 on an obese woman who had no saphenous vein and was not suitable for a femoral vein transposition, 1 on a diabetic woman whose saphenous vein loop clotted after 5 months and 1 on a female patient with severe peripheral vascular disease. The patient with bilateral subclavian vein occlusion had a brachial artery to internal jugular vein PTFE graft. The PTFE graft to the jugular vein has been patent and regularly needled with a follow-up of 4 months. Four saphenous vein fistulae were regularly used for dialysis; 2 were never used. Five saphenous fistulae clotted after an average life span of 4 months (range 3 weeks-9 months) and 1 is still patent and in use (5 months). Both femoral vein transpositions have been patent and have been needled 3 times a week with a follow-up of 10 and 4 months; one had to be revised surgically after 9 months. Of the 3 axillary artery to popliteal vein grafts, 1 had to be tied off after a week because of severe steal syndrome and 2 have been patent (20 months follow-up) and have been needled regularly ever since. Seventy percent of these patients have been dialyzed line-free through their fistula despite severe central vein stenosis or obstruction for periods of 9-18 months when this review was undertaken. Although the follow-up needs to be longer, we discuss the surgical, radiologic, and dialysis features of these patients and propose a management pathway for central vein stenosis or occlusion.  相似文献   
49.
OBJECTIVE: To evaluate the therapeutic effect of high-intensity focused ultrasound (HIFU) combined with chemotherapy (paclitaxel + estramustine) on AT2 Dunning adenocarcinoma, as no satisfactory treatment for localized prostate cancer is available for patients with a poor prognosis, e.g. stage T3, a high Gleason score, or a prostate-specific antigen level of >15 ng/mL. MATERIALS AND METHODS: Forty-one Dunning AT2 tumour-bearing Copenhagen rats were divided into four groups, i.e. control, chemotherapy, HIFU, and chemotherapy + HIFU (the last three treated for 1 week). The growth in tumour volume was recorded for 3 weeks, the point at which tumour volume was considered to have doubled (doubling time). The growth curves of each group were plotted and evaluated statistically. RESULTS: At 30 days of follow-up the distributions of tumour volume with treatment group were significantly different (P < 0.001); volumes were significantly greater in the control than in the chemotherapy-only or in the HIFU-only group (both P = 0.006). The greatest difference was between the chemotherapy + HIFU and the control group. The tumour doubling times were 13.2 days for HIFU-only, 31.2 days for chemotherapy + HIFU and 7.7 days for the controls. CONCLUSION: These results suggest that this combined therapy could be useful for treating patients with high-risk prostate cancer.  相似文献   
50.
Although HLA matching is beneficial in clinical transplantation, it is not feasible to select a completely HLA matched donor for every potential recipient because of the enormous polymorphism of the HLA system. As a consequence, the majority of the recipients will be transplanted with a mismatched donor organ or hematopoietic stem cell transplant. For this large group of patients it is important to take advantage of the differential immunogenicity of HLA mismatches and to select for them a donor with HLA mismatches of low immunogenicity, the so-called acceptable mismatches. The differential immunogenicity of HLA mismatches can be determined by either retrospective analysis of graft survival data or by in vitro assays measuring T-cell and B-cell alloreactivity. A recently developed computer algorithm (HLAMatchmaker) can be instrumental in selecting donors with HLA mismatches, which do not lead to alloantibody formation. The theoretical background and practical implications of this acceptable mismatch approach are discussed.  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