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   2467篇
  免费   167篇
  国内免费   9篇
耳鼻咽喉   19篇
儿科学   83篇
妇产科学   80篇
基础医学   447篇
口腔科学   82篇
临床医学   198篇
内科学   513篇
皮肤病学   53篇
神经病学   246篇
特种医学   52篇
外科学   307篇
综合类   16篇
预防医学   151篇
眼科学   34篇
药学   124篇
肿瘤学   238篇
  2023年   18篇
  2022年   47篇
  2021年   72篇
  2020年   37篇
  2019年   47篇
  2018年   44篇
  2017年   39篇
  2016年   58篇
  2015年   50篇
  2014年   72篇
  2013年   119篇
  2012年   153篇
  2011年   172篇
  2010年   88篇
  2009年   89篇
  2008年   163篇
  2007年   156篇
  2006年   147篇
  2005年   132篇
  2004年   121篇
  2003年   93篇
  2002年   101篇
  2001年   68篇
  2000年   64篇
  1999年   66篇
  1998年   27篇
  1997年   14篇
  1996年   15篇
  1995年   10篇
  1994年   17篇
  1992年   25篇
  1991年   23篇
  1990年   18篇
  1989年   15篇
  1988年   15篇
  1987年   12篇
  1986年   19篇
  1985年   18篇
  1984年   10篇
  1983年   10篇
  1982年   10篇
  1979年   14篇
  1978年   11篇
  1977年   11篇
  1975年   10篇
  1974年   21篇
  1973年   14篇
  1972年   10篇
  1970年   9篇
  1969年   15篇
排序方式: 共有2643条查询结果,搜索用时 15 毫秒
91.
Carcinoma ex pleomorphic adenoma (CXPA) is a rare salivary gland malignancy most often reported within the parotid gland. Of the salivary gland tumours that occur within the minor salivary glands at least 50% are reported to be malignant. This proves to be inaccurate when describing salivary gland tumours within the upper lip which are usually benign. A Medline search of the English language literature yields only one case report of a CXPA located within the upper lip. The authors present a second case report of CXPA within the upper lip and a review of its pathologic features and management.  相似文献   
92.
ObjectivesDespite converging basic scientific and clinical evidence of the link between chronic pain and depression, existing therapies do not often take advantage of this overlap. Here, we provide a critical review of the literature that highlights the intersection in brain networks between chronic low back pain (CLBP) and depression and discuss findings from previous deep brain stimulation (DBS) studies for pain. Based on a multidimensional model of pain processing and the connectivity of the subgenual cingulate cortex (SCC) with areas that are implicated in both CLBP and depression, we propose a novel approach to the treatment of CLBP using DBS of the SCC.Materials and MethodsA narrative review with literature assessment.ResultsCLBP is associated with a shift away from somatosensory representation toward brain regions that mediate emotional processes. There is a high degree of overlap between these regions and those involved in depression, including the anterior cingulate cortex, medial prefrontal cortex, nucleus accumbens, and amygdala. Whereas target sites from previous DBS trials for pain were not anatomically positioned to engage these areas and their associated networks, the SCC is structurally connected to all of these regions as well as others involved in mediating sensory, cognitive, and affective processing in CLBP.ConclusionsCLBP and depression share a common underlying brain network interconnected by the SCC. Current data and novel technology provide an optimal opportunity to develop clinically effective trials of SCC DBS for CLBP.  相似文献   
93.
Hypotension commonly occurs during hemodialysis (HD). Hypotension can result from an absolute reduction in plasma volume following excessive ultrafiltration or from a reduction in vascular tone. We hypothesized that changes in vascular tone could occur during dialysis. Aortic pulse wave velocity (aPWV) was measured in 197 HD patients, mean age 63.3 ± 16.6 years, 62% male, 49% diabetic, during a single HD session. aPWV did not change (9.6 ± 2.2 vs. 9.6 ± 2.2 m/s) with HD. Systolic blood pressure (SBP) declined from 151 ± 31 to 147 ± 32 after 20 min and to 140 ± 36 mm Hg on completion of HD (P < 0.05), with an ultrafiltration volume of 2.2 ± 0.9 L over a 3.9 ± 0.4 h HD session. Aortic SBP declined from 154 ± 32 to 146 ± 29 after 20 min and 143 ± 35 at the end of HD, P < 0.001. Aortic augmentation index (Aortic Aix) decreased from 65% (52–79%) to 36.7% (23.3–52.9%) by 20 min and to 34.3 (15.1–49.1%) on completion of HD (P < 0.05), and brachial augmentation index (brachial Aix) from 5.7% (?25.2 to 27.5%) to ?1.9% (?2.2 to 30.1%) and ?6.6% (?44 to 22.7%), respectively, P < 0.05. Diastolic reflection area (DRA) increased from 36.7 (27.9–46.3) to 40.4 (32.2–51) after 20 min and 47.1 (34.2–60.5) on completion of HD, P < 0.05. We report changes in arterial tone within 20 min of starting HD, when minimal ultrafiltration has occurred, suggesting that volume changes may not be the only predisposing cause of intradialytic hypotension. The combination of a fall in SBP and a rise in DRA would suggest a reduction in coronary blood flow in keeping with reports of “myocardial stunning” during HD.  相似文献   
94.
The prevalence of sleep disorders during childhood has been estimated to range from 25 to 43 %. The aim of this review is to determine the prevalence of sleep disorders and possible associations with chronic kidney disease (CKD)-related factors and health-related quality of life (HRQOL) in children with CKD. An electronic systematic literature search for sleep disorders in children with CKD in Pubmed, Embase and the Cochrane Library Databases identified seven relevant articles for review, all of which reported an increased prevalence of sleep disorders in children with CKD. Five studies included children with CKD undergoing dialysis, and two studies included only non-dialysis patients. In all studies the presence of sleep disturbances was assessed by questionnaires; only one study compared the results of a validated questionnaire with laboratory-based polysomnography. The prevalence of any sleep disorder ranged from 77 to 85 % in dialysis patients, to 32–50 % in transplanted patients and 40–50 % in non-dialysis patients. The most commonly studied disorder was restless legs syndrome, which presented at a prevalence of 10–35 %. Three studies showed significant associations between presence of sleep disorders and HRQOL. We found consistent evidence of an increased prevalence of sleep disturbances in children with CKD, and these seemed to play a critical role in HRQOL.  相似文献   
95.
96.
Penile malignancies are rare in developed countries. The authors present a case of a penile urethral mesenchymal tumor occurring in a 51-year-old Caucasian male and displaying light microscopic, immunohistochemical, and ultrastructural features suggestive of a pacemaker cell type, combined with a lack of diagnostic features of any other established tumor category. The immunohistochemical profile was intensely positive for vimentin, PKC θ, and NSE and weakly positive to nonreactive for CD34 and smooth muscle actin, and entirely negative for CD117 (c-kit), S-100, and other markers. C-kit and PDGFRA gene analysis showed no mutations. Electron microscopy revealed tumor cells with plentiful cytoplasm and cytoplasmic processes/filopodia, both filled with intermediate filaments and occasional solitary focal densities. There were also prominent smooth endoplasmic reticulum cisternae, caveolae, neurosecretory granules, particularly concentrated in cytoplasmic processes, and synaptic-type structures. Poorly formed basal lamina, gap junctions, and intercellular collagen aggregates, consistent with skeinoid-type fibers, were also noted. Interstitial cells with potential pacemaker function have been recently described in the lower urinary tract, including the urethra, and this tumor may be related to this cellular phenotype.  相似文献   
97.
BACKGROUND: Throughout pregnancy maternal adipose tissue is metabolically active, producing adipocytokines involved in the process of insulin resistance. We explored the role of serum adipocytokines, including the newly identified adipocytokine visfatin, in the process of insulin resistance in normal pregnancy. METHODS: We examined 80 pregnant nonobese, nondiabetic white women during the 3 trimesters of pregnancy. All study participants underwent anthropometric measurements, adipocytokine evaluation, and a 75-g oral glucose tolerance test. Homeostasis mathematical model assessment (HOMA-R), insulin sensitivity index (ISI), and indices of beta-cell secretion were calculated. RESULTS: Maternal weight, percentage total body fat, hip circumference, and indices of beta-cell secretion increased significantly during the 3 trimesters, and HOMA-R and ISI increased and decreased, respectively, in the 3rd trimester. During early pregnancy, insulin resistance, beta-cell secretion, and weight correlated positively with leptin. During the 1st trimester, visfatin correlated negatively with percentage body fat and was the best positive predictor of 2nd trimester ISI. In the 2nd trimester, serum visfatin was the best negative predictor of percentage body fat. CONCLUSIONS: During normal pregnancy of nonobese, nondiabetic women, adipose tissue increases, accompanied by a significant progressive increase of insulin resistance. Visfatin concentrations in the 1st trimester positively predict insulin sensitivity during the 2nd trimester. Body fat mass during 1st trimester of pregnancy is negatively associated with insulin sensitivity during the 2nd trimester and perhaps should be kept under control.  相似文献   
98.
Background/aim

End-stage kidney disease (ESKD) is strongly associated with factors that aggravate the physical activity level and body composition status of hemodialysis patients (HD). Even though exercise in HD patients have shown remarkable benefits on hemodialysis adequacy, it is yet inconclusive if exercise can positively affect body composition parameters or if dialysis adequacy may affect body composition status. This study aimed to investigate the effect of a 6-month intradialytic exercise training program on dialysis adequacy indices and body composition parameters in HD patients.

Study design

A total of 24 HD patients were randomly assigned into two equally sized groups. The exercise group (EX group) participated in a 6-month intradialytic moderate-intensity aerobic exercise training program at the beginning of the HD sessions, three times a week for 60 min, and maintained a Borg’s Rating of Perceived Exertion score between 13 and 14. The Control group (C group) remained untrained. At baseline, during, and at the end of the 6-month study, we assessed single-pool Kt/V, urea reduction ratio (URR), and body composition parameters, such as extracellular water (ECW)/ intracellular water (ICW) ratio, body mass index (BMI) and lean tissue mass (LTM). In all patients, the 6-min-walking test (6MWT) was performed as a marker of physical performance.

Results

A significant increase of both Kt/V (increase by 19%, p?=?0.01), and URR (increase by 7%, p?=?0.03) values has been observed in the EX group after the 6-month training program. Similarly, a statistically significant increase in 6MWT distance (from 442?±?67 m to 481?±?68 m, p?=?0.02) in the EX group has also been found, compared to the C group (from 393?±?59 m to 427?±?81 m, p?=?0.06). Neither EX nor C group has shown significant changes in body composition parameters. After training, linear regression analysis revealed a strong positive correlation between Kt/V and 6MWT changes (r?=?0.74, p?=?0.04) in the EX group.

Conclusions

Six months of intradialytic aerobic exercise might increase dialysis adequacy, by increasing Kt/V and URR, and physical performance, regardless of changes in body composition indices.

  相似文献   
99.
Diabetic foot ulceration is a common and severe complication of diabetes, causing substantial social, medical, and economic burdens. Treatment of foot ulcers remains challenging, thus requiring increasing awareness and more efficient management. This study investigates the efficacy of ointments, containing as main active ingredient the olive oil extract of the marine isopod Ceratothoa oestroides, in the treatment of patients with diabetic foot ulcers. Fifty‐two patients were allocated into four treatment groups either receiving therapy with an ointment containing extract of C. oestroides or extract of C. oestroides and eosin or extract of C. oestroides and cefaclor or no treatment. Patients were monitored for a period of 135 days by evaluation of transepidermal water loss, skin hydration, planimetry, photo‐documentation, and clinical condition. Treatment with the extract of C. oestroides demonstrated significant healing properties that became evident after 45 days of treatment and resulted in complete ulcer healing in 61% of the patients. A significant improvement in transepidermal water loss (p < 0.001), skin hydration levels (p < 0.001), and wound area (p < 0.001) was observed in all patients. Similar efficacy was demonstrated for the combination of C. oestroides extract with eosin treatment (p < 0.001). On the contrary, the combination of C. oestroides extract with cefaclor antibiotic agent completely inhibited the healing properties of the isopod extract and did not improve water loss, skin hydration, or wound area. An important factor for C. oestroides extract healing properties is its selective activity against Gram negative bacteria. Ointments containing C. oestroides extract alone or combined with the antimicrobial agent eosin emerges as an effective regimen for the treatment of diabetic foot ulcers.  相似文献   
100.
Tailgut cysts are developmental hamartomas found in the presacral space. They are usually detected incidentally during physical examinations or imaging studies. However, they may cause symptoms due to compression of nearby organs. Due to their potential malignant transformation, surgical resection is warranted, while routine biopsy is considered controversial because of the concern about infection of the tailgut cyst and needle-track implantation of malignant cells. The co-existence of a carcinoid in a tailgut cyst is extremely rare. Only 16 cases have been reported previously, the vast majority of which were found in females. We herein present the case of a carcinoid in a tailgut cyst found in a male patient, discuss the potential pathogenesis of tailgut carcinoids, and underline the fact that their previous consideration of the condition as a female-restricted entity should be rejected.  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