全文获取类型
收费全文 | 163077篇 |
免费 | 2995篇 |
国内免费 | 1620篇 |
专业分类
耳鼻咽喉 | 1652篇 |
儿科学 | 6115篇 |
妇产科学 | 2671篇 |
基础医学 | 19141篇 |
口腔科学 | 4275篇 |
临床医学 | 10810篇 |
内科学 | 31533篇 |
皮肤病学 | 2904篇 |
神经病学 | 9610篇 |
特种医学 | 3324篇 |
外国民族医学 | 2篇 |
外科学 | 25940篇 |
综合类 | 9538篇 |
一般理论 | 4篇 |
预防医学 | 8582篇 |
眼科学 | 3262篇 |
药学 | 17517篇 |
10篇 | |
中国医学 | 6148篇 |
肿瘤学 | 4654篇 |
出版年
2022年 | 895篇 |
2021年 | 2113篇 |
2020年 | 979篇 |
2019年 | 12508篇 |
2018年 | 12136篇 |
2017年 | 5373篇 |
2016年 | 1002篇 |
2015年 | 1010篇 |
2014年 | 2437篇 |
2013年 | 4189篇 |
2012年 | 2839篇 |
2011年 | 2733篇 |
2010年 | 2323篇 |
2009年 | 2287篇 |
2008年 | 2693篇 |
2007年 | 3692篇 |
2006年 | 3969篇 |
2005年 | 3902篇 |
2004年 | 3045篇 |
2003年 | 3126篇 |
2002年 | 3040篇 |
2001年 | 3039篇 |
2000年 | 3280篇 |
1999年 | 2960篇 |
1998年 | 3033篇 |
1997年 | 2389篇 |
1996年 | 2237篇 |
1995年 | 2604篇 |
1994年 | 2422篇 |
1993年 | 1884篇 |
1992年 | 1482篇 |
1991年 | 1478篇 |
1990年 | 1231篇 |
1989年 | 976篇 |
1988年 | 1013篇 |
1987年 | 979篇 |
1986年 | 819篇 |
1985年 | 5399篇 |
1984年 | 7276篇 |
1983年 | 5823篇 |
1982年 | 6254篇 |
1981年 | 5705篇 |
1980年 | 4902篇 |
1979年 | 4958篇 |
1978年 | 4061篇 |
1977年 | 3047篇 |
1976年 | 3522篇 |
1975年 | 2732篇 |
1974年 | 2523篇 |
1973年 | 2226篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
Eitaro Ito Akihiro Takai Yoshinori Imai Hiromi Otani Yoshihiro Onishi Yosuke Yamamoto Kohei Ogawa Taiji Tohyama Shunichi Fukuhara Yasutsugu Takada 《Surgery》2019,165(2):353-359
Background
Controversy continues as to whether single-incision laparoscopic cholecystectomy, with the somewhat larger incision at the umbilicus, may lead to a worse postoperative quality of life and more pain compared with the more classic 4-port laparoscopic cholecystectomy. The aim of this study was to compare single-incision and 4-port laparoscopic cholecystectomy from the perspective of quality of life.Methods
This study was a multicenter, parallel-group, open-label, randomized clinical trial. A total of 120 patients who were scheduled to undergo elective cholecystectomy were randomly assigned 1:1 into the single-incision laparoscopic cholecystectomy or the 4-port laparoscopic cholecystectomy group and then assessed continuously for 2 weeks during the postoperative period. The primary outcome was quality of life, defined as the time to resume normal daily activities. Postoperative pain was also assessed. To explore the heterogeneity of treatment effects, we assessed the interactions of sex, age, and working status on recovery time.Results
A total of 58 patients in the single-incision group and 53 in the 4-port group (n?=?111, 47 male, mean age 57 years) were analyzed. The mean time to resume daily activities was 10.2 days and 8.8 days, respectively, for single-incision and 4-port laparoscopic cholecystectomy (95% confidence interval –0.4 to 3.2, P?=?.12). Similarly, the time to relief from postoperative pain did not differ significantly between the groups. Statistically insignificant but qualitative interactions were noted; in the subgroups of women, full-time workers, and patients younger than 60 years, recovery tended to be slower after single-incision laparoscopic cholecystectomy.Conclusion
Postoperative quality of life did not differ substantially between single-incision laparoscopic cholecystectomy and 4-port laparoscopic cholecystectomy. Patients younger than 60 years, women, and full-time workers tended to have a somewhat slower recovery after single-incision laparoscopic cholecystectomy. 相似文献133.
A. Ríos A.I. López-Navas M.A. Ayala G. Garrido M.J. Sebastián J. Carrillo Á. Sánchez J. Flores-Medina J.J. Ruiz-Manzanera A.M. Hernández P. Ramírez P. Parrilla 《Transplantation proceedings》2019,51(2):258-260
The Latin American population has a double way of immigration, one toward the United States by proximity and another toward Spain by sociocultural affinity. This population increase is affecting organ donation and transplantation in receiving countries.
Objective
To analyze the brain death (BD) concept knowledge in the Dominican Republic immigrant population in Florida (United States) and Spain.Method
Population under study: Population born in the Dominican Republic, resident in Florida (United States) and in Spain. Inclusion criteria: Population older than 15 years stratified by age and sex. Assessment instrument: Donation attitude questionnaire PCID-DTO-Ríos. Fieldwork: Random selection based on stratification. Immigration support association collaboration in Florida and Spain was needed to locate potential respondents. Completion was anonymous and self-administered, with verbal consent.Results
A total of 123 respondents, 57 residents in Spain and 66 in Florida, have been included in the study. The 27% (n = 33) of the respondents knowledgeable of the BD concept consider it the death of an individual. Of the remainder, 52% (n = 64) do not know about it, and the remaining 21% (n = 26) believe it does not mean the death of a patient. No differences were observed regarding migration countries (P > .05). There was no association of the BD concept with other psychosocial factors analyzed or with the attitude toward organ donation.Conclusions
Knowledge of the BD concept among the Dominican immigrant population is similar in Spain and Florida, and, unlike most studies, there is no objective association with the attitude toward organ donation. 相似文献134.
135.
136.
137.
138.
139.
140.
Learning to Discretize: Solving 1D Scalar Conservation Laws via Deep Reinforcement Learning
下载免费PDF全文
![点击此处可从《Communications In Computational Physics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yufei Wang Ziju Shen Zichao Long & Bin Dong 《Communications In Computational Physics》2020,28(5):2158-2179
Conservation laws are considered to be fundamental laws of nature. It has
broad applications in many fields, including physics, chemistry, biology, geology, and
engineering. Solving the differential equations associated with conservation laws is a
major branch in computational mathematics. The recent success of machine learning,
especially deep learning in areas such as computer vision and natural language processing, has attracted a lot of attention from the community of computational mathematics and inspired many intriguing works in combining machine learning with traditional methods. In this paper, we are the first to view numerical PDE solvers as an
MDP and to use (deep) RL to learn new solvers. As proof of concept, we focus on
1-dimensional scalar conservation laws. We deploy the machinery of deep reinforcement learning to train a policy network that can decide on how the numerical solutions should be approximated in a sequential and spatial-temporal adaptive manner.
We will show that the problem of solving conservation laws can be naturally viewed
as a sequential decision-making process, and the numerical schemes learned in such a
way can easily enforce long-term accuracy. Furthermore, the learned policy network
is carefully designed to determine a good local discrete approximation based on the
current state of the solution, which essentially makes the proposed method a meta-learning approach. In other words, the proposed method is capable of learning how to
discretize for a given situation mimicking human experts. Finally, we will provide details on how the policy network is trained, how well it performs compared with some
state-of-the-art numerical solvers such as WENO schemes, and supervised learning
based approach L3D and PINN, and how well it generalizes. 相似文献