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   6755篇
  免费   532篇
  国内免费   19篇
耳鼻咽喉   19篇
儿科学   137篇
妇产科学   127篇
基础医学   1117篇
口腔科学   38篇
临床医学   720篇
内科学   1522篇
皮肤病学   167篇
神经病学   724篇
特种医学   139篇
外科学   555篇
综合类   25篇
一般理论   3篇
预防医学   608篇
眼科学   89篇
药学   592篇
中国医学   11篇
肿瘤学   713篇
  2024年   13篇
  2023年   62篇
  2022年   112篇
  2021年   206篇
  2020年   114篇
  2019年   200篇
  2018年   204篇
  2017年   131篇
  2016年   176篇
  2015年   190篇
  2014年   262篇
  2013年   365篇
  2012年   551篇
  2011年   515篇
  2010年   295篇
  2009年   222篇
  2008年   444篇
  2007年   468篇
  2006年   412篇
  2005年   373篇
  2004年   394篇
  2003年   348篇
  2002年   310篇
  2001年   74篇
  2000年   55篇
  1999年   80篇
  1998年   70篇
  1997年   46篇
  1996年   56篇
  1995年   32篇
  1994年   24篇
  1993年   24篇
  1992年   27篇
  1991年   24篇
  1990年   33篇
  1989年   38篇
  1988年   27篇
  1987年   28篇
  1986年   9篇
  1985年   26篇
  1984年   10篇
  1983年   13篇
  1982年   18篇
  1981年   16篇
  1980年   8篇
  1979年   15篇
  1978年   12篇
  1969年   12篇
  1965年   8篇
  1963年   7篇
排序方式: 共有7306条查询结果,搜索用时 0 毫秒
51.
Robaux S  Blunt C  Viel E  Cuvillon P  Nouguier P  Dautel G  Boileau S  Girard F  Bouaziz H 《Anesthesia and analgesia》2004,98(4):1172-7, table of contents
Adjuncts to local anesthetics for peripheral plexus blockade may enhance the quality and duration of anesthesia and postoperative analgesia. The analgesic, tramadol, has a unique mechanism of action that suggests efficacy as such an adjunct. It displays a central analgesic and peripheral local anesthetic effect. We designed a prospective, randomized, controlled and double-blind clinical trial to assess the effect of tramadol added to brachial plexus anesthesia. One-hundred patients scheduled for carpal tunnel release surgery under brachial plexus anesthesia were randomized into four groups. All patients received 1.5% mepivacaine 40 mL plus a study solution containing either isotonic sodium chloride (Group P, n = 17), tramadol 40 mg (Group T(40), n = 22), tramadol 100 mg (Group T(100), n = 20) or tramadol 200 mg (Group T(200), n = 20). We evaluated the time of onset of anesthesia, duration of sensory and motor blockade, duration and quality of postoperative analgesia, and occurrence of adverse effects. Onset and duration of sensory and motor blocks were not different among groups. The number of patients requesting analgesia in the postoperative period was significantly less in the 3 tramadol groups compared with the placebo group (P = 0.02); this was also noted with the placebo and T(40) groups compared with the T(200) group. No statistical significance was demonstrated between the placebo and the T(40) group or the T(100) group and the T(200) group. Furthermore, there was a significant trend effect among groups applying the Cochran-Armitage tendency test (P = 0.003), suggesting a dose-dependent decrease for additional postoperative analgesia requirements when tramadol was added. Side effects did not differ among groups, although they were more frequently recorded in the T groups. Our study suggests that tramadol added to 1.5% mepivacaine for brachial plexus block enhances in a dose-dependent manner the duration of analgesia with acceptable side effects. However, the safety of tramadol has to be investigated before allowing its use in clinical practice. IMPLICATIONS: Tramadol's unique mechanism of action suggests efficacy as a local anesthetic adjunct for peripheral plexus blockade. Our study demonstrates that tramadol, added to mepivacaine for brachial plexus anesthesia, extends the duration and improves the quality of postoperative analgesia in a dose dependent fashion with acceptable side effects.  相似文献   
52.
IntroductionSecondary hyperparathyroidism sometimes is lacking despite authentic vitamin D insufficiency (VDI) and the concept of functional hypoparathyroidism with a protective role on bone status has been proposed. Therefore, we tested the hypothesis that its prevalence was very low in a population of women with a peripheral fragility fracture.MethodsWe conducted our study in postmenopausal women, admitted for such a fracture in our Fracture Liaison Service. All had bone mineral density (BMD), biochemical assessment and a medical visit.ResultsTwo hundred and thirty seven women (72.9 ± 11.6-year-old) were included and 90.4% had VDI (25[OH]D  30 ng/mL). Yet, 87.9% of the latter had normal PTH levels less or equal to 64 ng/L. In this population with VDI (n = 214), we found no PTH plateau level related to 25(OH)D. Since a recent study reported an increase in the risk of fracture only when 25(OH)D was below 15 ng/mL, we then used this value as a new threshold. We observed a significant difference in hip BMD between patients with 25(OH)D either less or equal to or greater than 15 ng/mL. However, 81.2% of the formers were still with normal PTH with no difference in BMD whether PTH level was above or within normal range.ConclusionIn a population of postmenopausal women with a fragility fracture, we found that 25(OH)D less or equal to 15 ng/mL was associated with significantly lower hip BMD. Even using this low threshold, we found a high prevalence of functional hypoparathyroidism and it was not associated with any difference in hip or spine BMD. Overall, our results do not support the hypothesis of a protective effect of this biological profile.  相似文献   
53.
The case study on Jeanne Masson, a 95-year-old widow living at home, is cause to reflect upon the specific nature of psychic disability when defined as the inability to decide. It highlights the changes required in care giving when a patient is diagnosed with Alzheimer's disease, an irreversible cognitive impairment, as opposed to stress, a curable affective disorder. In this case, the diagnosis brought to a head the daily crisis that worsened when changes were made in the household without any consultation among the children (three married sons) and information on Jeanne's medical condition was not communicated properly. The professional home care givers and all the family members got caught in a cycle of mutual disrepute that marked the decision-making process till, after several hospitalizations, Jeanne was finally put in an old people's home. The interpretation of Jeanne's financial behavior and eating habits as symptoms of Alzheimer's disease put paid to her attempts to save face. This led her into a process of self-dispossession that some of her close relatives tried to prevent. As soon as the day-to-day upheavals and health problems came to an end, the protagonists of this drama erased all memory of the practical and interpretative violence that Jeanne was subjected to.  相似文献   
54.
55.
After kidney transplantation, C4d is an incomplete marker of acute antibody‐mediated rejection (AMR) and C1q‐binding donor‐specific antibodies (DSA) have been associated with allograft survival. However, the impact on allograft survival of C1q+ DSA after clinical AMR has not been studied yet. We analysed retrospectively in clinical AMR C4d staining and C1q‐binding impact on allograft survival. We compared clinical, histological and serological features of C4d− and C4d+ AMR, C1q+ and C1q− DSA AMR and analysed C4d and C1q‐binding impact on allograft survival. Among 500 for‐cause kidney allograft biopsies, 48 fulfilled AMR criteria. C4d+ AMR [= 18 (37.5%)] have significantly higher number class I DSA (P = 0.02), higher microvascular score (P = 0.02) and more transplant glomerulopathy (P = 0.04). C1q+ AMR [N = 20 (44%)] presented with significantly more class I and class II DSA (P = 0.005 and 0.04) and C4d+ staining (P = 0.01). Graft losses were significantly higher in the C4d+ group (P = 0.04) but similar in C1q groups. C4d+ but not C1q+ binding was an independent risk factor for graft loss [HR = 2.65; (1.11–6.34); P = 0.028]. In our cohort of clinical AMR, C4d+ staining but not C1q+ binding is an independent risk factor for graft loss. Allograft loss and patient survival were similar in C1q+ and C1q− AMR.  相似文献   
56.
In 2002, the United Network for Organ Sharing proposed increasing the pool of donor kidneys to include Expanded Criteria Donor (ECD). Outside the USA, the ECD definition remains the one used without questioning whether such a graft allocation criterion is valid worldwide. We performed a meta‐analysis to quantify the differences between ECD and Standard Criteria Donor (SCD) transplants. We paid particular attention to select studies in which the methodology was appropriate and we took into consideration the geographical area. Thirty‐two publications were included. Only five studies, all from the USA, reported confounder‐adjusted hazard ratios comparing the survival outcomes between ECD and SCD kidney transplant recipients. These five studies confirmed that ECD recipients seemed to have poorer prognosis. From 29 studies reporting appropriate survival curves, we estimated the 5‐year pooled nonadjusted survivals for ECD and SCD recipients. The relative differences between the two groups were lower in Europe than in North America, particularly for death‐censored graft failure. It is of primary importance to propose appropriate studies for external validation of the ECD criteria in non‐US kidney transplant recipients.  相似文献   
57.

Background

Morbidity after gastrectomy remains high. The potentially modifiable risk factors have not been well described. This study considers a series of potentially modifiable patient-specific and perioperative characteristics that could be considered to reduce morbidity and mortality after gastrectomy.

Methods

This retrospective cohort study includes adults in the ACS NSQIP PUF dataset who underwent gastrectomy between 2011 and 2013. Sequential multivariable models were used to estimate effects of clinical covariates on study outcomes including morbidity, mortality, readmission, and reoperation.

Results

Three thousand six hundred and seventy-eight patients underwent gastrectomy. A majority of patients had distal gastrectomy (N?=?2,799, 76.1 %) and had resection for malignancy (N?=?2,316, 63.0 %). Seven hundred and ninety-eight patients (21.7 %) experienced a major complication. Reoperation was required in 290 patients (7.9 %). Thirty-day mortality was 5.2 %. Age (OR?=?1.01, 95 % CI?=?1.01–1.02, p?=?0.001), preoperative malnutrition (OR?=?1.65, 95 % CI?=?1.35–2.02, p?<?0.001), total gastrectomy (OR?=?1.63, 95 % CI?=?1.31–2.03, p?<?0.001), benign indication for resection (OR?=?1.60, 95 % CI?=?1.29–1.97, p?<?0.001), blood transfusion (OR?=?2.57, 95 % CI?=?2.10–3.13, p?<?0.001), and intraoperative placement of a feeding tubes (OR?=?1.28, 95 % CI?=?1.00–1.62, p?=?0.047) were independently associated with increased risk of morbidity. Association between tobacco use and morbidity was statistically marginal (OR?=?1.23, 95 % CI?=?0.99–1.53, p?=?0.064). All-cause postoperative morbidity had significant associations with reoperation, readmission, and mortality (all p?<?0.001).

Conclusions

Mitigation of perioperative risk factors including smoking and malnutrition as well as identified operative considerations may improve outcomes after gastrectomy. Postoperative morbidity has the strongest association with other measures of poor outcome: reoperation, readmission, and mortality.
  相似文献   
58.
Advancements in burn care therapy have extended survival of seriously burned patients, exposing burn patients to increased risk of infectious complications, notably fungal infections. We performed a 12-year review of autopsied patients with severe burns for the presence of fungal infection at the US Army Institute of Surgical Research Burn Center between February 1991 and November 2003. The primary goal was to identify the relationship between fungal element noted in autopsy and mortality, and to determine contributing factors that increase a patient's susceptibility to fungal infection. A total of 228 deaths (6.1%) resulted from the 3751 admissions of which 97 underwent autopsy. Fungal elements were identified on histopathology in 44% (43 of 97) of autopsied patients with an attributable mortality of 33% (14 of 43). Aspergillus and Candida were the most frequently recovered fungi, but Aspergillus was recovered in 13 of the 14 cases with fungus identified as an attributable cause of death. The most common sites of infections with attributable mortality were wounds (86%) and the pulmonary system (14%). Total body surface area (TBSA) burn and length of stay (survival after burn) were identified as contributing factors for the incidence of fungal element in autopsy on ROC curve analysis. More severely injured patients with greater %TBSA burn injury and full-thickness burns require a longer recovery period resulting in a longer hospital stay. The propensity for fungal infection increases the longer the wound is present. Therefore, the development of products to close the wound more rapidly, improvement in topical antifungal therapy with mold activity for treating wounds, and implementation of appropriate systemic antifungal therapy may improve outcome for severely injured burn victims susceptible to fungal infections.  相似文献   
59.
PURPOSE: To evaluate the long-term safety and efficacy of Intacs segments (Addition Technology, Inc.) for the treatment of keratoconus in terms of intraoperative and postoperative complications, visual outcome, restoration of contact lens tolerance, and inhibition of disease progression. SETTING: Service d'Ophtalmologie, CHU Pellegrin, Bordeaux, France. METHODS: This prospective, 2-year follow-up study comprised 100 keratoconic eyes with clear central corneas and contact lens intolerance. The best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), refractive error, keratometry, pachymetry, and slitlamp examination were assessed preoperatively and 1 and 2 years after Intacs implantation. RESULTS: At 2 years, the UCVA and BCVA improved in 80.5% and 68.3% of eyes, respectively (P<.001). The proportion of eyes with a BCVA >or=0.5 (20/40) increased from 22.0% at baseline to 51.2% and 53.7% at 1 year and 2 years, respectively (P<.001). The manifest refraction spherical equivalent improved from a mean of -6.93 diopters (D) +/- 3.91 (SD) preoperatively to -4.01 +/- 3.16 D at 1 year and -3.80 +/- 2.73 D at 2 years (P<.001). The mean keratometry readings decreased from 50.1 +/- 5.6 D preoperatively to 46.4 +/- 5.3 D at 1 year and 46.8 +/- 4.9 D at 2 years (P<.001). Contact lens tolerance was restored in over 80% of cases. Postoperative slitlamp observations revealed no clinically significant issues. The segments were removed from 4 eyes without complications or sequelae. CONCLUSION: Intacs implantation was a safe and efficacious treatment for keratoconus. Significant and sustained improvements in objective visual outcomes were achieved in most cases, with restoration of contact lens tolerance.  相似文献   
60.
    

Ethnopharmacological relevance

The leaves of Annona muricata are used in Cameroon to manage diabetes and its complications. The aim of this study was to evaluate the antidiabetic, antioxidant activities and the potential toxicity of aqueous extract of Annona muricata in streptozotocin-induced diabetic rats.

Material and methods

Oral administration of Annona muricata aqueous extract (100 mg/kg or 200 mg/kg) was studied in normal and streptozotocin-induced diabetic rats. In long term treatment, 2 weeks after streptozotocin-induced diabetic rats, animals received plant extract during 28 consecutive days. For a protective effect, extract was administered 3 days prior to streptozotocin exposure and animals were observed 2 weeks without treatment.

Results

The plant extract was not effective in normal rats. In diabetic rats, single administration of the extract significantly reduced blood glucose levels by 75% and 58.22% respectively at the dose of 100 mg/kg and 200 mg/kg as compared to the initial value. Treatment of normal rats 3 days prior to diabetes induction showed that, Annona muricata extract has no effect within 72 h following STZ injection. However, after 14 days post-treatment, the extract at the dose of 100 mg/kg significantly reduced blood glucose levels as compared with initial value and diabetic control rats. Immunohistochemical staining of pancreatic β-cells of diabetic rats treated with the dose of 100 mg/kg expressed strong staining for β-cell compared to diabetic control. In a long-term study daily administration of Annona muricata aqueous extract for 28 days to diabetic rats, reduced blood glucose levels, serum creatinine, MDA, AST, ALT activity, and nitrite levels LDL-cholesterol. Total cholesterol, triglycerides, SOD, and CAT activity contents were restored.

Conclusion

These different results show that the antidiabetic activity of Annona muricata aqueous extract can be explained by its hypolipidaemic effect, its antioxidant and protective action on pancreatic β-cells, which in turn improve glucose metabolism.  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