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   1811篇
  免费   120篇
  国内免费   2篇
耳鼻咽喉   19篇
儿科学   52篇
妇产科学   43篇
基础医学   252篇
口腔科学   48篇
临床医学   152篇
内科学   295篇
皮肤病学   27篇
神经病学   111篇
特种医学   113篇
外科学   232篇
综合类   40篇
预防医学   116篇
眼科学   51篇
药学   199篇
中国医学   24篇
肿瘤学   159篇
  2023年   13篇
  2022年   26篇
  2021年   55篇
  2020年   31篇
  2019年   41篇
  2018年   46篇
  2017年   44篇
  2016年   52篇
  2015年   49篇
  2014年   72篇
  2013年   83篇
  2012年   113篇
  2011年   110篇
  2010年   70篇
  2009年   53篇
  2008年   81篇
  2007年   87篇
  2006年   103篇
  2005年   85篇
  2004年   76篇
  2003年   65篇
  2002年   61篇
  2001年   40篇
  2000年   39篇
  1999年   51篇
  1998年   14篇
  1997年   18篇
  1996年   18篇
  1995年   7篇
  1994年   9篇
  1993年   7篇
  1992年   36篇
  1991年   32篇
  1990年   25篇
  1989年   12篇
  1988年   20篇
  1987年   17篇
  1986年   20篇
  1985年   16篇
  1984年   13篇
  1983年   10篇
  1982年   6篇
  1981年   8篇
  1979年   8篇
  1978年   5篇
  1975年   5篇
  1974年   9篇
  1972年   9篇
  1970年   7篇
  1944年   4篇
排序方式: 共有1933条查询结果,搜索用时 0 毫秒
71.
Use of organs from donors testing positive for hepatitis B virus (HBV) may safely expand the donor pool. The American Society of Transplantation convened a multidisciplinary expert panel that reviewed the existing literature and developed consensus recommendations for recipient management following the use of organs from HBV positive donors. Transmission risk is highest with liver donors and significantly lower with non‐liver (kidney and thoracic) donors. Antiviral prophylaxis significantly reduces the rate of transmission to liver recipients from isolated HBV core antibody positive (anti‐HBc+) donors. Organs from anti‐HBc+ donors should be considered for all adult transplant candidates after an individualized assessment of the risks and benefits and appropriate patient consent. Indefinite antiviral prophylaxis is recommended in liver recipients with no immunity or vaccine immunity but not in liver recipients with natural immunity. Antiviral prophylaxis may be considered for up to 1 year in susceptible non‐liver recipients but is not recommended in immune non‐liver recipients. Although no longer the treatment of choice in patients with chronic HBV, lamivudine remains the most cost‐effective choice for prophylaxis in this setting. Hepatitis B immunoglobulin is not recommended.  相似文献   
72.
73.
Within artificial intelligence, machine learning (ML) efforts in radiation oncology have augmented the transition from generalized to personalized treatment delivery. Although their impact on quality and safety of radiation therapy has been limited, they are increasingly being used throughout radiation therapy workflows. Various data-driven approaches have been used for outcome prediction, CT simulation, clinical decision support, knowledge-based planning, adaptive radiation therapy, plan validation, machine quality assurance, and process quality assurance; however, there are many challenges that need to be addressed with the creation and usage of ML algorithms as well as the interpretation and dissemination of findings. In this review, the authors present current applications of ML in radiation oncology quality and safety initiatives, discuss challenges faced by the radiation oncology community, and suggest future directions.  相似文献   
74.

Purpose

To compare overall survival and toxicities after yttrium-90 (90Y) radioembolization and chemoembolization with drug-eluting embolics (DEE) in patients with infiltrative hepatocellular carcinoma (HCC).

Materials and Methods

Retrospective review of 50 patients with infiltrative HCC without main portal vein invasion who were treated with 90Y radioembolization (n = 26) or DEE chemoembolization (n = 24) between March 2007 and August 2012 was completed. Infiltrative tumors were defined by cross-sectional imaging as masses that lacked well-demarcated boundaries, and treatment allocations were made by a multidisciplinary tumor board. Median age was 63 years; median tumor diameter was 9.0 cm; and there were no significant differences between groups in performance status, severity of liver disease, or HCC stage. Toxicities were graded by Common Terminology Criteria for Adverse Events v4.03. Overall survival from treatment was assessed by Kaplan-Meier analysis, with analysis of potential predictors of survival with log-rank test.

Results

There was no difference in the average number of procedures performed in each treatment group (DEE, 1.5 ± 1.1; 90Y, 1.6 ± 0.5; P = .97), and technical success was achieved in all cases. Abdominal pain (73% vs 33%; P = .004) and fever (38% vs 8%; P = .01) were more frequent after DEE chemoembolization. There was no significant difference in median overall survival between treatment groups after treatment (DEE, 9.9 months; 90Y, 8.1 months; P = .11).

Conclusions

90Y radioembolization and DEE chemoembolization provided similar overall survival in the treatment of infiltrative HCC without main portal vein invasion. Abdominal pain and fever were more frequent after DEE chemoembolization.  相似文献   
75.

Purpose

To estimate the least costly routine exchange frequency for percutaneous nephrostomies (PCNs) placed for malignant urinary obstruction, as measured by annual hospital charges, and to estimate the financial impact of patient compliance.

Materials and Methods

Patients with PCNs placed for malignant urinary obstruction were studied from 2011 to 2013. Exchanges were classified as routine or due to 1 of 3 complication types: mechanical (tube dislodgment), obstruction, or infection. Representative cases were identified, and median representative charges were used as inputs for the model. Accelerated failure time and Markov chain Monte Carlo models were used to estimate distribution of exchange types and annual hospital charges under different routine exchange frequency and compliance scenarios.

Results

Long-term PCN management was required in 57 patients, with 87 total exchange encounters. Median representative hospital charges for pyelonephritis and obstruction were 11.8 and 9.3 times greater, respectively, than a routine exchange. The projected proportion of routine exchanges increased and the projected proportion of infection-related exchanges decreased when moving from a 90-day exchange with 50% compliance to a 60-day exchange with 75% compliance, and this was associated with a projected reduction in annual charges. Projected cost reductions resulting from increased compliance were generally greater than reductions resulting from changes in exchange frequency.

Conclusions

This simulation model suggests that the optimal routine exchange interval for PCN exchange in patients with malignant urinary obstruction is approximately 60 days and that the degree of reduction in charges likely depends more on patient compliance than exact exchange interval.  相似文献   
76.
77.
Neurohydatidosis     
Early and non‐invasive evaluation of hydatid infestation of brain and spine is of paramount importance, especially in endemic areas. We present a spectrum of imaging findings in neurohydatidosis with a brief review of literature.  相似文献   
78.
OBJECTIVE: Our objective was to determine the normal sequence of neurobehavioral development in the human fetus between 14 weeks' gestation and delivery. STUDY DESIGN: The study was performed by longitudinal ultrasonographic observation of 45 low-risk singleton fetuses. RESULTS: During the first half of the midtrimester there was a high rate of spontaneous movement that appeared randomly distributed. By the end of that trimester an increase in the duration of intervals of quiescence resulted in activity appearing cyclically distributed, with the duration of quiet cycles progressively increasing to term. Fetal mouthing and breathing were linked with cyclic behavior from the time of their emergence. Fetal heart rate pattern A could be recognized from around 32 weeks, due to a reduction in baseline variability in quiet cycles after 30 weeks, whereas pattern B could be recognized several weeks earlier. From the time cyclic behavior and heart rate patterns could be recognized, intervals of coincidence of the fetal behavioral state variables increased progressively with advancing gestation.  相似文献   
79.
The purpose of the study was to evaluate the neuromuscular transmission defect in preeclamptic women receiving intravenous magnesium sulfate and to study the correlation of the degree of defect with serum magnesium and calcium levels. The study population included: group 1, 14 preeclamptic women receiving magnesium sulfate and undergoing induction of labor; group 2, six preeclamptic women studied in the postpartum period while receiving magnesium sulfate; and group 3, 10 normotensive women undergoing induction of labor. The neuromuscular transmission studies were performed with standard techniques before and during the administration of magnesium sulfate. During magnesium sulfate therapy patients in groups 1 and 2 showed abnormal responses characterized by an initial low-amplitude muscle action potential followed by a progressive increase in the amplitudes of the successive responses. There was significant correlation between the degree of the neuromuscular transmission defect and serum magnesium levels, serum calcium levels, and the magnesium/calcium ratio in groups 1 and 2. All studies were normal in group 3. The findings confirm the occurrence of abnormal neuromuscular transmission in preeclamptic women receiving magnesium sulfate, and the intensity of the defect correlates significantly with increased serum magnesium levels and decreased serum calcium levels.  相似文献   
80.
Several reports have noted an increase in white matter hyperintensities (WMH) on MRI scans of adult patients with bipolar disorder. We investigated whether this increase was also evident in a group of adolescent patients with bipolar disorder. The sample consisted of 15 bipolar patients, 19 patients with schizophrenia and 16 healthy comparison subjects. All subjects were adolescents. WMH were blindly rated on T2-weighted and PD-weighted MRI scans using our own scale with documented inter-rater reliability. WMH were present in 10 of 15 bipolar patients (67%), seven of 19 patients with schizophrenia (37%) and five of 16 comparison subjects (31%). The bipolar adolescent group had a statistically significant increased presence of WMH compared both with healthy comparison subjects and the schizophrenic group. The association between WMH and bipolar disorder appears to extend to the adolescent years.  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