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   5005篇
  免费   193篇
  国内免费   63篇
耳鼻咽喉   82篇
儿科学   82篇
妇产科学   148篇
基础医学   369篇
口腔科学   300篇
临床医学   361篇
内科学   1363篇
皮肤病学   91篇
神经病学   469篇
特种医学   167篇
外科学   1031篇
综合类   20篇
一般理论   1篇
预防医学   175篇
眼科学   125篇
药学   193篇
中国医学   3篇
肿瘤学   281篇
  2025年   3篇
  2024年   45篇
  2023年   75篇
  2022年   118篇
  2021年   211篇
  2020年   133篇
  2019年   182篇
  2018年   197篇
  2017年   131篇
  2016年   179篇
  2015年   212篇
  2014年   258篇
  2013年   258篇
  2012年   415篇
  2011年   451篇
  2010年   255篇
  2009年   233篇
  2008年   345篇
  2007年   335篇
  2006年   312篇
  2005年   276篇
  2004年   239篇
  2003年   152篇
  2002年   126篇
  2001年   20篇
  2000年   12篇
  1999年   16篇
  1998年   12篇
  1997年   11篇
  1996年   11篇
  1995年   7篇
  1994年   6篇
  1993年   5篇
  1992年   1篇
  1991年   3篇
  1990年   1篇
  1988年   1篇
  1986年   2篇
  1984年   1篇
  1983年   2篇
  1982年   4篇
  1980年   1篇
  1976年   1篇
  1972年   1篇
  1962年   1篇
  1893年   1篇
排序方式: 共有5261条查询结果,搜索用时 15 毫秒
21.
A group of 140 women with a body mass index (BMI) < or = 24 kg/m(2) undergoing 291 cycles was compared with a group of 138 women with a BMI >24 kg/m(2) in 291 cycles, with respect to duration of ovarian stimulation and dose of gonadotrophin, number of oocytes collected, cleavage and implantation rate, clinical pregnancy, miscarriage and delivery rates. Patients with a BMI > 24 kg/m(2) demonstrated a significant decrease in the number of follicles after stimulation (P = 0.01), a comparative increase in the number ampoules of gonadotrophin used (P = 0.03) and a lower number of eggs collected (P = 0.05). The mean number of embryos on days 1, 2 and 3 was significantly lower in the group with BMI > 24 kg/m(2) (P < 0.001). No significant difference was found in clinical pregnancy and miscarriage rates between the two groups. In spite of the lower response in women with BMI > 24 kg/m(2), the delivery rate per retrieval was not different (24.6 versus 24.8%). These results indicate a lower stimulation response in women with elevated BMI, but no adverse effect on IVF outcome. In relation to wellbeing, however, it is recommended that patients with a high BMI reduce their weight before IVF treatment.  相似文献   
22.
23.
Eating disorders (EDs) are increasingly emerging as a health risk in men, yet men remain underrepresented in ED research, including interventional trials. This underrepresentation of men may have facilitated the development of women-centered ED treatments that result in suboptimal outcomes for men. The present study retrospectively compared pre- vs. post-treatment outcomes between age-, diagnosis-, and length-of-treatment-matched samples of n = 200 men and n = 200 women with Anorexia Nervosa (AN), Bulimia Nervosa (BN), Binge Eating Disorder (BED), or Eating Disorder Not Otherwise Specified (EDNOS), treated in the same setting during the same period, and using the same measurements. Compared to women, men with AN showed marked improvements in weight gains during treatment as well as in ED-specific cognitions and general psychopathology. Likewise, men with BED showed marked weight loss during treatment compared to women with BED; ED-specific cognitions and general psychopathology outcomes were comparable in this case. For BN and EDNOS, weight, ED-specific cognitions, and general psychopathology outcomes remained largely comparable between men and women. Implications for treatments are discussed.  相似文献   
24.
The aim of the current study was to investigate whether a Total Lifestyle Index (TLI), including adherence to the Mediterranean diet, sleep duration, physical activity and engagement in activities of daily living, is associated with cognitive health over time and dementia risk, in a representative cohort of older people. A total of 1018 non-demented community-dwelling older adults ≥65 years old (60% women) from the HELIAD study were included. A comprehensive neurological and neuropsychological assessment was conducted at baseline and at the 3-year follow-up evaluating cognitive functioning, and a dementia diagnosis was set. Diet, physical activity, sleep duration and engagement in activities of daily living were assessed using standard, validated questionnaires at baseline. Sixty-one participants developed dementia at follow-up; participants who developed dementia were older and had fewer years of education compared with participants with normal cognition. With the exception of sleep duration, participants with normal cognition at follow-up scored higher in the individual lifestyle factors compared to those who developed dementia. Regarding TLI, values were lower for participants with dementia compared with those with normal cognition. Each additional unit of the TLI was associated with 0.5% of a standard deviation less decline per year of the Global Cognition score, whereas for each additional unit of the TLI, the risk for dementia was reduced by 0.2% per year (p < 0.05). Our results suggest that greater adherence to a healthy lifestyle pattern is associated with a slower decline of cognitive function and reduced dementia risk.  相似文献   
25.
Sarcomas are a group of rare mesenchymal malignant tumors that arise from transformed cells of the mesenchymal connective tissue, which are challenging to treat. The majority of sarcomas are soft tissue sarcomas (STSs; 75%) and this heterogeneous group of tumors is further comprised of gastrointestinal stromal tumors (~15%) and bone sarcomas (10%). Although surgery remains the current primary therapeutic approach for localized disease, recurrent, metastatic and refractory sarcomas require cytotoxic chemotherapy, which usually yields poor results. Therefore the efficiency of sarcoma treatment imposes a difficult problem. Furthermore, even though progress has been made towards understanding the underlying molecular signaling pathways of sarcoma, there are limited treatment options. The aim of the present study was therefore to perform a systematic literature review of the available clinical evidence regarding the role of tyrosine kinase inhibitors (TKIs) in patients with recurrent or refractory STSs and bone sarcomas over the last two decades. Tyrosine kinases are principal elements of several intracellular molecular signaling pathways. Deregulation of these proteins has been implicated in driving oncogenesis via the crosstalk of pivotal cellular signaling pathways and cascades, including cell proliferation, migration, angiogenesis and apoptosis. Subsequently, small molecule TKIs that target these proteins provide a novel potential therapeutic approach for several types of tumor by offering significant clinical benefits. Among the eligible articles, there were 45 prospective clinical trials, primarily multicentric, single arm, phase II and non-randomized. Numerous studies have reported promising results regarding the use of TKIs, mainly resulting in disease control in patients with STSs. The lack of randomized clinical trials demonstrates the ambiguous efficiency of various studied treatment options, which therefore currently limits the approved drugs used in clinical practice. Research both in clinical and preclinical settings is needed to shed light on the underlying molecular drivers of sarcomagenesis and will identify novel therapeutic approaches for pretreated patients.  相似文献   
26.
Hepatocellular carcinoma (HCC) is a malignant neoplasm associated with significant mortality worldwide. The most commonly applied curative options include liver...  相似文献   
27.
We compared estimates for base excess of extracellular fluid (BE(ecf); mmol/L) obtained in five clinically used blood gas analyzers: AVL Compact 2 (Roche Diagnostics, Mannheim, Germany), Ciba-Corning 860 (Bayer Diagnostics, Fernwald, Germany), IL 1620 (Instrumentation Laboratories, Lexington, MA), Stat Profile Ultra (Nova Biomedical, Waltham, MA), and ABL 510 (Radiometer, Copenhagen, Denmark). A total of 134 measurements per analyzer were obtained in arterial and venous blood samples from 10 patients undergoing cardiac surgery and 65 measurements per analyzer in venous blood samples from 2 healthy volunteers. The blood samples were equilibrated in a tonometer with gases of known composition (37 degrees C). Additional theoretical studies were performed to evaluate the relationship between pH and calculated BE(ecf) value (with varied PCO(2)) using the formulas of the various analyzers. The standard deviations of repeated measurements were 0.24 mmol/L for ABL 510 and approximately 0.45 mmol/L for the other 4 analyzers. The maximal systematic difference between the average of all measurements of each analyzer was 3.7 mmol/L; this was primarily attributable to differences in measuring pH, and, to a lesser extent, to differences in calculation and determination of PCO(2). Comparison of the results from samples with different oxygen saturation showed that the relative alkalinity of deoxygenated hemoglobin (Haldane effect) can also influence the determinations of BE(ecf). IMPLICATIONS: A clinically useful way to quantify nonrespiratory disturbances of the acid-base balance is calculation of the base excess of extracellular fluid by using blood gas analyzers. In this study, we found significant variability in estimates of base excess of extracellular fluid obtained with five analyzers from different manufacturers. This variability is attributable to multiple factors, including lack of correction for deoxygenated hemoglobin (Haldane effect).  相似文献   
28.
This the case of a 63 year-old man with end-stage renal disease (on chronic hemodialysis), unstable angina and significantly impaired myocardial contractility with low left ventricular ejection fraction, who underwent off-pump one vessel coronary bypass surgery. Combined continuous levosimendan and norepinephrine infusion (at 0.07 μg/kg/min and 0.05 μg/kg/min respectively) started immediately after anesthesia induction and continued for 24 hours. The levosimendan/norepinephrine combination helped maintain an appropriate hemodynamic profile, thereby contributing to uneventful completion of surgery and postoperative hemodynamic stability. Although levosimendan is considered contraindicated in ESRD patients, this case report suggests that combined perioperative levosimendan/norepinephrine administration can be useful in carefully selected hemodialysis patients with impaired myocardial contractility and ongoing myocardial ischemia, who undergo off-pump myocardial revascularization surgery.  相似文献   
29.
Functional bracing has been widely accepted as the gold standard for treating humeral shaft fractures conservatively. We conducted a literature review to verify the efficacy of this treatment method. Sixteen case series and two comparative studies fulfilled the criteria set. Analysis of these clinical studies showed that humeral shaft fractures when treated with functional bracing heal in an average of 10.7 weeks. Union rate is high (94.5%). Statistical analysis showed that proximal third fractures and AO type A fractures have a higher non-union rate although this is not statistical significant. Residual deformity and joint stiffness are considered the main drawbacks of conservative treatment. Angulation - usually varus - rarely exceeded 10°, while full shoulder and elbow motion was achieved in 80% and 85% of the patients, respectively. Nevertheless, in the few studies that subjective parameters such as functional scores, pain and quality of life were assessed results were not so promising.  相似文献   
30.

Aim

Numerous studies have been published regarding the comparison between intramedullary nail and the dynamic hip screw and plate for the fixation of intertrochanteric fractures in elderly patients. In this paper we present a comparative study of these two methods regarding their systemic effects on this group of patients.

Materials-methods

This is a randomized trial of 120 consecutive patients with an intertrochanteric fracture treated with either extramedullary fixation (dynamic hip screw and plate; DHS, Synthes-Stratec, Oberdorf, Switzerland) or intramedullary nail (Gamma nail, Stryker Howmedica, Freiburg, Germany and Endovis BA, Citieffe, Bologna, Italy).The parameters that we assessed pre-operatively, in addition to their demographics, included their mental state (MMSE), their nutritional and immune state and their pulmonary function. Intra-operatively we calculated the amount of radiation exposure, the amount of blood loss and the length of operative time for each procedure. Postoperatively we repeated the calculation of the mental and pulmonary state and the blood loss, during days 1, 3, and 10 and related them to the ease of the patient's mobilization.

Results

Decreased bleeding and post-operative pain, reduced post-operative morbidity and faster recovery of function were better but not significant in the group of intramedullary fixation (all p > 0.05). However, in the same group there were slightly more patients in whom the MMSE was falling, together with their pulmonary function, suggesting that this method probably predisposes to higher chances of pulmonary dysfunction and the possibility of pulmonary embolism.

Conclusion

We found no significant differences between the two methods of stabilization of these fractures regarding their systemic effects perioperatively. The classic dynamic hip screw can preserve its position as a safe and effective solution for these already vulnerable patients having sustained a trochanteric fracture against the novel intramedullary techniques.  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