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   2405篇
  免费   147篇
  国内免费   3篇
耳鼻咽喉   25篇
儿科学   90篇
妇产科学   50篇
基础医学   321篇
口腔科学   55篇
临床医学   163篇
内科学   466篇
皮肤病学   50篇
神经病学   221篇
特种医学   42篇
外科学   509篇
综合类   37篇
一般理论   8篇
预防医学   196篇
眼科学   16篇
药学   182篇
中国医学   24篇
肿瘤学   100篇
  2023年   14篇
  2022年   49篇
  2021年   96篇
  2020年   56篇
  2019年   89篇
  2018年   86篇
  2017年   47篇
  2016年   53篇
  2015年   67篇
  2014年   93篇
  2013年   114篇
  2012年   175篇
  2011年   163篇
  2010年   102篇
  2009年   103篇
  2008年   156篇
  2007年   156篇
  2006年   138篇
  2005年   120篇
  2004年   108篇
  2003年   81篇
  2002年   61篇
  2001年   72篇
  2000年   86篇
  1999年   34篇
  1998年   15篇
  1997年   12篇
  1996年   10篇
  1995年   14篇
  1994年   14篇
  1993年   3篇
  1992年   18篇
  1991年   11篇
  1990年   15篇
  1989年   10篇
  1988年   11篇
  1987年   19篇
  1986年   10篇
  1985年   9篇
  1984年   5篇
  1983年   6篇
  1981年   4篇
  1980年   3篇
  1979年   8篇
  1978年   7篇
  1977年   3篇
  1974年   6篇
  1973年   5篇
  1971年   2篇
  1969年   3篇
排序方式: 共有2555条查询结果,搜索用时 171 毫秒
41.
42.
43.
The aim of this study was to determine the presence and morphology of the anterolateral ligament (ALL) of the knee in a sample of fetuses. We hypothesized that the ALL is present in sample fetuses and its origin is not related to repetitive stresses throughout life. Forty fresh‐frozen knees from cadaveric fetuses were dissected using a standard technique. The ALL and other structures in the anterolateral compartment of the knee were identified. The details of the femoral and tibial attachments, course and relationships with anatomical structures of the ALL were identified, recorded, and quantitatively characterized. The ALL was identified in 100% of the dissected knees. We found three anatomical patterns regarding the femoral attachment: (1) Proximal and posterior to the fibular collateral ligament (55%); (2) Together with the fibular collateral ligament (25%); and (3). Anterior and distal to it (20%). The ALL was extracapsular with an oblique course attaching into the anterolateral aspect of the tibia, midway between the midpoint of Gerdy's tubercle and the fibular head. The ALL has a strong attachment to the lateral meniscus, creating two fascicles: proximal or meniscofemoral and distal or meniscotibial. The ALL is a constant, extracapsular anatomical structure in the anterolateral compartment of the knee, present from the later prenatal period of life. Its morphology shows three different patterns of femoral attachment in relation to the fibular collateral ligament position, a strong attachment in the lateral meniscus, and a constant tibial attachment. Clin. Anat. 30:625–634, 2017. © 2017 Wiley Periodicals, Inc.  相似文献   
44.
45.
46.
47.

Background

Treatment‐related mortality and abandonment of therapy are major barriers to successful treatment of childhood acute lymphoblastic leukemia (ALL) in the developing world.

Procedure

A collaboration was undertaken between Instituto Nacional de Cancerologia (Bogota, Colombia), which serves a poor patient population in an upper‐middle income country, and Dana‐Farber/Boston Children's Cancer and Blood Disorders Center (Boston, USA). Several interventions aimed at reducing toxic deaths and abandonment were implemented, including a reduced‐intensity treatment regimen and a psychosocial effort targeting abandonment. We performed a cohort study to assess impact.

Results

The Study Population comprised 99 children with ALL diagnosed between 2007 and 2010, and the Historic Cohort comprised 181 children treated prior to the study interventions (1995–2004). Significant improvements were achieved in the rate of deaths in complete remission (13% to 3%; P = 0.005), abandonment (32% to 9%; P < 0.001), and event‐free survival with abandonment considered an event (47% to 65% at 2 years; P = 0.016). However, relapse rate did not improve. Medically unnecessary treatment delays were common, and landmark analysis revealed that initiating the PIII phase of therapy ≥4 weeks delayed predicted markedly inferior disease‐free survival (P = 0.016). Conversely, patients who received therapy without excessive delays had outcomes approaching those achieved in high‐income countries.

Conclusions

Implementation of a twinning program was followed by reductions in abandonment and toxic deaths, but relapse rate did not improve. Inappropriate treatment delays were common and strongly predicted treatment failure. These findings highlight the importance of adherence to treatment schedule for effective therapy of ALL. Pediatr Blood Cancer 2015;62:1395–1402. © 2015 Wiley Periodicals, Inc.  相似文献   
48.

Background

During the post-partum period, most women wish to delay or prevent future pregnancies. Despite this, the unmet need for family planning up to a year after delivery is higher than at any other time. This study aims to assess fertility intention, contraceptive usage and unmet need for family planning amongst women who are six weeks postpartum, as well as to identify those at greatest risk of having an unmet need for family planning during this period.

Methods

Using the NICHD Global Network for Women’s and Children’s Health Research’s multi-site, prospective, ongoing, active surveillance system to track pregnancies and births in 100 rural geographic clusters in 5 countries (India, Pakistan, Zambia, Kenya and Guatemala), we assessed fertility intention and contraceptive usage at day 42 post-partum.

Results

We gathered data on 36,687 women in the post-partum period. Less than 5% of these women wished to have another pregnancy within the year. Despite this, rates of modern contraceptive usage varied widely and unmet need ranged from 25% to 96%. Even amongst users of modern contraceptives, the uptake of the most effective long-acting reversible contraceptives (intrauterine devices) was low. Women of age less than 20 years, parity of two or less, limited education and those who deliver at home were at highest risk for having unmet need.

Conclusions

Six weeks postpartum, almost all women wish to delay or prevent a future pregnancy. Even in sites where early contraceptive adoption is common, there is substantial unmet need for family planning. This is consistently highest amongst women below the age of 20 years. Interventions aimed at increasing the adoption of effective contraceptive methods are urgently needed in the majority of sites in order to reduce unmet need and to improve both maternal and infant outcomes, especially amongst young women.

Study registration

Clinicaltrials.gov (ID# NCT01073475)
  相似文献   
49.
Herein, rare-earth manganite, La0.67Sr0.33MnO3, has been prepared by a citric acid-assisted sol–gel auto-combustion method at a maintained pH value of 11. Room-temperature X-ray diffraction (RT-XRD) data analysis revealed a rhombohedral structure for the sample with the space group R3c, which was further confirmed by synchrotron radiation X-ray diffraction (SR-XRD). Rietveld refinement was carried out for both spectra, which confirmed the SR-XRD and RT-XRD results and the various structural parameters. To determine any of the phase transitions in the sample, temperature-dependent X-ray diffraction corresponding to the temperatures of 100 K, 200 K, 250 K, and 325 K was carried out, and no new phase was found. Temperature-dependent Raman characterization confirmed the metallic phase of the sample with the reduced Jahn–Teller distortion. Scanning electron microscopy confirmed the growth in the grain size as a result of a high sintering temperature. Compositional verification was conducted using energy-dispersive analysis of X-ray diffraction (EDAX). Low-temperature dc resistivity measurement showed a metal-insulator transition temperature (TMI) of ≈178 K. The DSC-specific heat measurement shows the ferromagnetic metallic nature where heat capacity increases with an increase in temperature.

Herein, rare-earth manganite, La0.67Sr0.33MnO3, has been prepared by a citric acid-assisted sol–gel auto-combustion method at a maintained pH value of 11.  相似文献   
50.

Background

Cardiopulmonary resuscitation (CPR) is a key component of emergency care following cardiac arrest. A better understanding of factors that influence CPR outcomes and their prognostic implications would help guide care. A retrospective analysis of 800 adult patients that sustained an in- or out-of-hospital cardiac arrest and underwent CPR in the emergency department of a tertiary care facility in Karachi, Pakistan, between 2008 and 15 was conducted.

Methods

Patient demographics, clinical history, and CPR characteristics data were collected. Logistic regression model was applied to assess predictors of return of spontaneous circulation and survival to discharge. Analysis was conducted using SPSS v.21.0.

Results

Four hundred sixty-eight patients met the study’s inclusion criteria, and overall return of spontaneous circulation and survival to discharge were achieved in 128 (27.4%) and 35 (7.5%) patients respectively. Mean age of patients sustaining return of spontaneous circulation was 52 years and that of survival to discharge was 49 years. The independent predictors of return of spontaneous circulation included age ≤?49 years, witnessed arrest, ≤?30 min interval between collapse-to-start, and 1–4 shocks given during CPR (aOR (95% CI) 2.2 (1.3–3.6), 1.9 (1.0–3.7), 14.6 (4.9–43.4), and 3.0 (1.4–6.4) respectively), whereas, age ≤?52 years, bystander resuscitation, and initial rhythm documented (pulseless electrical activity and ventricular fibrillation) were independent predictors of survival to discharge (aOR (95% CI) 2.5 (0.9–6.5), 1.4 (0.5–3.8), 5.3 (1.5–18.4), and 3.1 (1.0–10.2) respectively).

Conclusion

Our study notes that while the majority of arrests occur out of the hospital, only a small proportion of those arrests receive on-site CPR, which is a key contributor to unfavorable outcomes in this group. It is recommended that effective pre-hospital emergency care systems be established in developing countries which could potentially improve post-arrest outcomes. Younger patients, CPR initiation soon after arrest, presenting rhythm of pulseless ventricular tachycardia and ventricular fibrillation, and those requiring up to four shocks to revive are more likely to achieve favorable outcomes.
  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