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   12850篇
  免费   688篇
  国内免费   54篇
耳鼻咽喉   179篇
儿科学   248篇
妇产科学   145篇
基础医学   2199篇
口腔科学   406篇
临床医学   1146篇
内科学   2150篇
皮肤病学   306篇
神经病学   1423篇
特种医学   988篇
外国民族医学   1篇
外科学   1877篇
综合类   56篇
一般理论   4篇
预防医学   481篇
眼科学   320篇
药学   830篇
中国医学   27篇
肿瘤学   806篇
  2023年   49篇
  2022年   46篇
  2021年   195篇
  2020年   139篇
  2019年   199篇
  2018年   229篇
  2017年   192篇
  2016年   259篇
  2015年   312篇
  2014年   372篇
  2013年   474篇
  2012年   717篇
  2011年   775篇
  2010年   507篇
  2009年   489篇
  2008年   802篇
  2007年   824篇
  2006年   866篇
  2005年   893篇
  2004年   777篇
  2003年   767篇
  2002年   746篇
  2001年   237篇
  2000年   228篇
  1999年   219篇
  1998年   163篇
  1997年   119篇
  1996年   119篇
  1995年   105篇
  1994年   95篇
  1993年   88篇
  1992年   94篇
  1991年   100篇
  1990年   88篇
  1989年   86篇
  1988年   82篇
  1987年   89篇
  1986年   63篇
  1985年   53篇
  1984年   51篇
  1983年   56篇
  1982年   37篇
  1981年   45篇
  1979年   63篇
  1978年   44篇
  1977年   43篇
  1976年   33篇
  1975年   51篇
  1973年   34篇
  1970年   33篇
排序方式: 共有10000条查询结果,搜索用时 640 毫秒
1.
2.
3.
4.
5.
6.
A method is presented for 3D MRI in an extended field of view (FOV) based on continuous motion of the patient table and an efficient acquisition scheme. A gradient-echo MR pulse sequence is applied with lateral (left-right (L/R)) frequency-encoding direction and slab selection along the direction of motion. Compensation for the table motion is achieved by a combination of slab tracking and data alignment in hybrid space. The method allows fast k-space coverage to be achieved, especially when a short sampling FOV is chosen along the direction of table motion, as is desirable for good image quality. The method can be incorporated into different acquisitions schemes, including segmented k-space scanning, which allows for contrast variation with the use of magnetization preparation. Head-to-toe images of volunteers were obtained with good quality using 3D spoiled gradient-echo sequences. As an example of magnetization-prepared imaging, fat/water separated images were acquired using chemical shift selective (CHESS) presaturation pulses.  相似文献   
7.
Background: Molecular theories of general anesthesia often are divided into two categories: (l) Anesthetics may bind specifically to proteins, such as ionic channels, and alter their function directly, and (2) anesthetics may alter the functions of integral membrane proteins indirectly through modification of the physical properties of the membrane. Recent studies have provided evidence that anesthetics can bind to proteins and modify their function directly, bringing into question the role of the membrane in anesthetic interactions. To reexamine the role of membrane lipids in anesthetic interactions, an experimental approach was used in which the membrane lipid composition could be systematically altered and the impact on anesthetic interactions with potential targets examined.

Methods: Sodium channels from human brain cortex were incorporated into planar lipid bilayers with increasing cholesterol content. The anesthetic suppression of these channels by pentobarbital was quantitatively examined by single channel measurements under voltage-clamp conditions.

Results: Changes in cholesterol content had no effect on measured channel properties in the absence of anesthetic. In the presence of pentobarbital, however, cholesterol inhibited anesthetic suppression of channel ionic currents, with 1.9% (weight/weight, corresponding to 3.5 mol%) cholesterol decreasing anesthetic suppression of sodium channels by half.  相似文献   

8.
The pilot study for a sentinel health events surveillance system for deaths among persons under age 45 with diabetes was conducted in six states in 1984 and 1985. Two hundred and thirty-three events were identified. Information from death certificates, physicians, and families revealed that 22% died from acute complications of diabetes and 53% from chronic complications. Blood pressure measurement and urinalysis testing had been performed in the last year for almost all of the decedents, but other preventive practices were reported less frequently. Hypertension was present in 57% and of those, was not controlled in 73%. Forty-four percent were cigarette smokers at the time of death. Agreement between physicians and families was generally higher for clinical conditions than for care practices. This surveillance system appears to yield information about the health care of persons with diabetes not readily available from other sources, although modifications may be necessary before implementation.  相似文献   
9.
In comparative histological and cytological studies on 270 prostatic carcinoma patients highly and moderately differentiated tumors were found to be more frequent histologically than cytologically. An early and reliable sign of response to hormone therapy proved to be reticularization and vacuolization of the nuclear chromatin. Follow-up studies by means of multiple aspiration biopsies with cytologic examinations seem to be more reliable in prognostic terms than examination of the histological tumor structure.  相似文献   
10.
Ramazzini is not only reputed to be the father of industrial hygiene, but must be thought to be the founder of occupational dermatology too. In his famous book about diseases of artists and craftsmen (De morbis artificium diatriba) he shows us numerous job-caused dermatoses, their occupational background, and makes proposals for their treatment and prophylaxis. The medical inspection of the work place and asking for the occupational history of the patient are tracing back to him too. His life is described.  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