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   66106篇
  免费   5710篇
  国内免费   1520篇
耳鼻咽喉   306篇
儿科学   750篇
妇产科学   677篇
基础医学   2984篇
口腔科学   887篇
临床医学   9162篇
内科学   4372篇
皮肤病学   462篇
神经病学   1512篇
特种医学   1386篇
外国民族医学   7篇
外科学   3489篇
综合类   14834篇
现状与发展   3篇
一般理论   89篇
预防医学   21195篇
眼科学   345篇
药学   5313篇
  365篇
中国医学   4078篇
肿瘤学   1120篇
  2024年   311篇
  2023年   1270篇
  2022年   2236篇
  2021年   2876篇
  2020年   3292篇
  2019年   2326篇
  2018年   2170篇
  2017年   2199篇
  2016年   2227篇
  2015年   2170篇
  2014年   4871篇
  2013年   5289篇
  2012年   4566篇
  2011年   4923篇
  2010年   3987篇
  2009年   3502篇
  2008年   3717篇
  2007年   3500篇
  2006年   3125篇
  2005年   2454篇
  2004年   2016篇
  2003年   1625篇
  2002年   1262篇
  2001年   1080篇
  2000年   875篇
  1999年   737篇
  1998年   609篇
  1997年   532篇
  1996年   470篇
  1995年   413篇
  1994年   323篇
  1993年   209篇
  1992年   209篇
  1991年   223篇
  1990年   190篇
  1989年   162篇
  1988年   159篇
  1987年   118篇
  1986年   155篇
  1985年   140篇
  1984年   135篇
  1983年   92篇
  1982年   100篇
  1981年   78篇
  1980年   95篇
  1979年   41篇
  1978年   70篇
  1977年   69篇
  1976年   61篇
  1975年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Out-of-hours organisations are responsible for the care of patients 70% of the time, and their GPs act as gatekeepers to secondary care services. This observational study identifies the variations in GPs' out-of-hours referral rates to secondary care and factors that could explain these variations. One hundred and forty-nine GPs who worked in one UK general practice out-of-hours cooperative which served 19 practices with 167 000 registered patients. Data on patients who accessed the out-of-hours service over 3 years (2001-2004) were examined. Factors thought to be predictors of variation in referral rates were investigated using logistic regression analysis. There was a fivefold difference in referral rates between the lowest and highest referring quartiles of GPs (OR [odds ratio] = 4.56, CI [confidence interval] = 3.86 to 5.38). The sex (female) of the clinician, the time of the consultation (11 pm to 7 am), and the place of the consultation (home visit) accounted for some, but not all, of the increased referral rates. A doctor working out-of-hours disproportionately influences the fate of the patient, the number of hospital admissions, and extra costs to the health service. There is a need for follow-up studies to investigate the factors associated with referral behaviour, and how the variation relates to patient factors and the resources available. These findings could be used when planning the staffing of out-of-hours services to optimise appropriate care and minimise patients' exposure to unnecessary intrusive and expensive hospital care.  相似文献   
92.
National Taiwan University College of Medicine (NTUCM) introduced small groups of teaching and basic-clinical integrated courses for medical students in 1992. By using computer network and multimedia techniques, this study tried to overcome barriers to learning in small group teaching. The Department of Medical Informatics of NTUCM established campus networking and computer classrooms and provided Internet and intranet network services including mail, netnews, bulletin board systems (BBS), world wide web (WWW), gopher, ftp and local file servers. To implement an interactive learning environment, the authors first tried mail lists, newsgroups and BBS. Next an integrated learning system prototype on the WWW was developed to provide functions including online syllabus, discussion boards simulated to BBS, online talk, interactive case studies, virtual classroom with video on demand (VOD) and Internet medical resources. The results showed that after the medical students completed the required course of medical informatics and had good network access using a network to communicate with each other became a daily practice. In the future, the system will extend to the tutoring of clinical practice and continuing medical education. The authors expect a national medical education network and more international cooperation and exchange.  相似文献   
93.
Optimizing the embryo transfer technique   总被引:7,自引:0,他引:7  
The technique of embryo transfer is very crucial and great attention and time should be given to this step. In order to optimize the embryo transfer technique, several precautions should be taken. The first and most important is to avoid the initiation of uterine contractility. This can be achieved by the use of soft catheters, gentle manipulation and by avoiding touching the fundus. Secondly, proper evaluation of the uterine cavity and utero-cervical angulation is very important, and can be achieved by performing dummy embryo transfer and by ultrasound evaluation of the utero-cervical angulation and uterine cavity length. Another important step is the removal of cervical mucus so that it does not stick to the catheter and inadvertently remove the embryo during catheter withdrawal. Finally, one has to be absolutely sure that the embryo transfer catheter has passed the internal cervical os and that the embryos are delivered gently inside the uterine cavity.  相似文献   
94.
Forty subjects participated in each of two experiments in which both lemon-line and cola-flavored beverages containing one of six sweeteners--sucrose, sodium saccharin, aspartame, acesulfam-K, and two calcium cyclamate/sodium saccharin blends (10:1 and 3.5:1)--were evaluated on similarity and adjective scales. The similarity data suggest that drinks containing sucrose and aspartame cannot be discriminated from one another in either a lemon-line or cola medium in this experimental design. Sucrose and aspartame were also statistically equivalent on every adjective scale for both lemon-line and cola drinks. On both similarity judgments and adjective scales, acesulfam-K and sodium saccharin were most different from sucrose. The calcium cyclamate/sodium saccharin blends tended to be less similar than aspartame but not as different from sucrose as the acesulfam-K or sodium saccharin sweetened beverages.  相似文献   
95.
A variety of adverse reactions to local anesthetics has been described, some of which are thought to be allergic. Different protocols of prick and intradermal skin tests as well as subcutaneous challenge tests are used to select a local anesthetic which can safely be used. Their long-term effectiveness has not yet been assessed. Twenty-eight patients with a history of adverse reaction to local anesthetics were evaluated over a 3-year period. Loss of consciousness occurred in eight patients, skin reaction in nine, and vagal symptoms in eight. Various reactions were recorded in the remaining three patients. Rapid spontaneous recovery was the rule, suggesting that immediate allergic reaction and, in particular, anaphylactic reaction were unlikely. Investigation allowed the selection of a tolerated anesthetic in all cases. Reexposure occurred in 19 patients 16–50 months after evaluation and 6.8 ± 5.5 years after the first reaction. No patient presented a second reaction. In conclusion, adverse reactions to local anesthetics seem to be, in most cases, not allergic in nature. Evaluation protocols are effective in selecting an agent susceptible to tolerance, but are time consuming. However, they probably contribute to an important reassurance effect that is likely to increase tolerance to subsequent local anesthetic administration. Simplification of the protocols and better patient selection are proposed.  相似文献   
96.
The first presymptomatic test for Huntington's disease was developed in the 1980s. With the detection of the gene causing the disorder in 1993, it became possible to do direct mutation tests with almost 100% sensitivity and specificity. The author discusses some of the ethical issues that arise when an adult child at 25% risk for the disease wishes to have the test, but the parent(s) at 50% risk refuses to have one. If the child tests positive, the genetic status of the parent will also be disclosed. No matter what course of action is chosen in this situation, the ethically legitimate interests of either child or parent might be violated. The author examines different alternatives and suggests a solution that might be acceptable to all parties.  相似文献   
97.
Unsharp masking is a widely used image-enhancement method in medical imaging. Hardware-based solutions can be developed to support high computational demand for unsharp masking, but they suffer from limited flexibility. Software solutions can easily incorporate new features and modify key parameters, such as filtering kernel size, but they have not been able to meet the fast computing requirement. Modern programmable mediaprocessors can meet both fast computing and flexibility requirements, which will benefit medical image computing. In this article, we present fast adaptive unsharp masking on two leading mediaprocessors or high-end digital signal processors, Hitachi/Equator Technologies MAP-CA and Texas Instruments TMS320C64x. For a 2k × 2k 16-bit image, our adaptive unsharp masking with a 201 × 201 boxcar kernel takes 225 ms on a 300-MHz MAP-CA and 74 ms on a 600-MHz TMS320C64x. This fast unsharp masking enables technologists and/or physicians to adjust parameters interactively for optimal quality assurance and image viewing.  相似文献   
98.
Human embryonic stem cells: research,ethics and policy   总被引:6,自引:0,他引:6  
The use of human embryos for research on embryonic stem (ES) cells is currently high on the ethical and political agenda in many countries. Despite the potential benefit of using human ES cells in the treatment of disease, their use remains controversial because of their derivation from early embryos. Here, we address some of the ethical issues surrounding the use of human embryos and human ES cells in the context of state-of-the-art research on the development of stem cell based transplantation therapy.  相似文献   
99.
Childhood obesity has increased worldwide over the past four decades. This quasi-experimental study aimed to assess the effectiveness of a multicomponent and multilevel school-based intervention (POIBA) at 3 years of follow-up. The nutrition intervention focused on food groups, food pyramid, nutrients, portions, and balanced menus. In total, 3624 children participated in the study. Anthropometric measurements and information on food frequency and behavior, physical activity, and daily screen use were collected in the intervention (IG) and comparison group (CG). Positive unadjusted changes toward adherence to recommendations were found for water, meat, sweets, and fried potato consumption, proper breakfast, not having dinner in front of the TV, out-of-school physical activity, and daily screen use. Three scores were used to calculate the proportion of children making more than one change to improve healthy habits regarding physical activity (global Activity score), nutrition (global Nutrition score), and both (global score). Students exposed to the intervention had a significantly better global Activity score (16.2% IG vs. 11.9% CG; p = 0.012) and Global score (63.9% IG vs. 58.5% CG; p = 0.025). Intervention effects on obesity incidence at 3-year follow-up lost significance but maintained the positive trend. In conclusion, school-based interventions including a family component could be useful to address the childhood obesity problem.  相似文献   
100.
糖尿病患者膳食营养分析   总被引:5,自引:0,他引:5  
目的 :探讨糖尿病患者膳食营养状况 ,提出改善糖尿病患者膳食结构的策略。方法 :对 2 2 5例糖尿病患者连续调查 3天膳食供给情况 ,建立数据库输入计算机 ,用SPSS软件进行分析。结果 :热能摄入量不符合要求者占77 3% ;蛋白质供给量不足者占患者总数的 75 6% ;47 6%的糖尿病患者脂肪摄入量超过标准 ;5 5 1%的糖尿病患者碳水化合物的摄入量不符合要求 ;膳食纤维摄入不足者占患者总数的 94 2 % ;维生素和无机盐中 ,除铁、核黄素和抗坏血酸供给量尚可 ,其余均不足。结论 :糖尿病患者膳食是不合理的 ,必须按照膳食治疗方案调节膳食  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