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   6598篇
  免费   505篇
  国内免费   10篇
耳鼻咽喉   51篇
儿科学   142篇
妇产科学   158篇
基础医学   1137篇
口腔科学   205篇
临床医学   615篇
内科学   1379篇
皮肤病学   193篇
神经病学   707篇
特种医学   263篇
外国民族医学   2篇
外科学   639篇
综合类   60篇
一般理论   5篇
预防医学   618篇
眼科学   44篇
药学   422篇
中国医学   16篇
肿瘤学   457篇
  2023年   31篇
  2022年   51篇
  2021年   113篇
  2020年   89篇
  2019年   106篇
  2018年   149篇
  2017年   106篇
  2016年   134篇
  2015年   138篇
  2014年   180篇
  2013年   250篇
  2012年   349篇
  2011年   349篇
  2010年   206篇
  2009年   192篇
  2008年   301篇
  2007年   296篇
  2006年   282篇
  2005年   307篇
  2004年   270篇
  2003年   258篇
  2002年   259篇
  2001年   223篇
  2000年   244篇
  1999年   201篇
  1998年   102篇
  1997年   74篇
  1996年   90篇
  1995年   62篇
  1994年   54篇
  1993年   66篇
  1992年   125篇
  1991年   142篇
  1990年   144篇
  1989年   110篇
  1988年   98篇
  1987年   90篇
  1986年   92篇
  1985年   101篇
  1984年   100篇
  1983年   52篇
  1982年   40篇
  1981年   32篇
  1979年   37篇
  1978年   32篇
  1977年   34篇
  1973年   28篇
  1972年   28篇
  1968年   31篇
  1967年   28篇
排序方式: 共有7113条查询结果,搜索用时 15 毫秒
11.
Body density and body impedance at 15 selected frequencies ranging from 1 to 1350 kHz were determined in 13 subjects on four consecutive days of the week. Bioelectrical impedance at the same frequencies was also determined in 11 subjects on the same day of the week during four consecutive weeks. Day-to-day variability of body density and body impedance and week-to-week variability of body impedance were studied. Statistical analyses did not reveal significant day- or week-effects in variabilities. The mean within-person variation in body density between days was 0.0019 kg/l (CV 0.2%). Mean within-person variation in body impedance between days was 57 ohms (CV 8.7%) at 1 kHz. At 5, 50 and 100 kHz the within-person variation between days was 16 ohms (CV 2.4%), 12 ohms (CV 2.1%) and 11 ohms (CV 2.0%), respectively. Mean within-person variation between weeks was 44 ohms (CV 2.4%) at 1, 5, 50 and 100 kHz, respectively. Overall the within-subject variability in impedance at all frequencies was higher in females. The larger mean within-person variation in impedance at 1 kHz could only partly be explained by variation in body weight and may be a real error in the measurement. Electrodes with a larger surface area reduced the variability to values comparable with those at higher frequencies. The day-to-day variation in impedance at higher frequencies causes an error in calculated FFM, which is about two times larger compared to the estimated error in FFM by body density.  相似文献   
12.
13.
Aberrations of fetal sexual development were studied in two retarded phenotypic female 46,XY dysgonadal sisters from a consanguineous marriage. Endocrine evaluation revealed an inadequate response of plasma-testosterone to human chorionic gonadotropin (hCG) stimulation and a normal response to adrenocorticotropic hormone (ACTH) administration. At exploratory laparotomy dysgenetic testes and remnants of the Müllerian and of the Wolffian duct were found. Loss of testicular function, resulting in male pseudohermaphroditism (MPH), can occur at different times during intrauterine development, resulting in a variety of clinical manifestations. A thorough evaluation is warranted in all patients in order to reach a correct diagnosis which is of importance for appropriate gender assignment and genetic counseling.  相似文献   
14.
In a multicenter study we selected 84 patients with fluctuating Parkinson's disease in order to evaluate the effects of controlled-release Sinemet 50/200 (=CR) versus standard Sinemet 25/100 (=STD) in an open-label 8-week titration period, followed by a double-blind, double-dummy 24-week treatment period. In contrast with previous double-blind studies, the efficacy of Sinemet CR proved to be significantly superior to that of Sinemet-STD according to NYUPDS and NUDS rating scales. This higher efficacy of Sinemet CR was not achieved at the expense of safety and/or tolerability. Actual total daily levodopa dosage in patients treated with Sinemet CR was increased by 33%; however, the plasma level of this dosage is calculated to be similar to that of the previous dosage of Sinemet-STD (bio-availability of Sinemet CR is 71%). Mean numbers of daily doses, off-hours, and off-periods were decreased significantly during Sinemet CR treatment. Although all other variables suggest that the number of on-hours had to be increased, statistical significance could not be reached in this respect.  相似文献   
15.
The present study was undertaken to determine whether alterations in the gallbladder sensitivity to cholecystokinin (CCK), apart from a reduced endogenous CCK secretion, contribute to the abnormally decreased postprandial gallbladder contraction in patients with coeliac disease. Gallbladder emptying, measured by cholescintigraphy, and plasma CCK levels, measured by radioimmunoassay, were studied during infusion of graded doses of the CCK analog cerulein in six coeliac patients with subtotal villous atrophy, six coeliac patients on a gluten-free diet with normal villous architecture, and nine control subjects. Both in the patients and in the controls infusion of stepwise increasing doses of cerulein, in the range of 1-16 ng.kg-1.h-1, induced dose-related changes in plasma CCK-like immunoreactivity (CCK-LI) (r = 0.99; p less than 0.001) and gallbladder emptying (r greater than 0.97; p less than 0.01-p less than 0.001). Plasma CCK-LI and gallbladder responses were not significantly different among untreated coeliac patients, treated coeliac patients, and controls. Gallbladder sensitivity to cerulein in untreated and treated coeliac patients was not significantly different from that in controls. It is concluded that the abnormally decreased gallbladder contraction in coeliac patients is the result of a reduced endogenous CCK secretion and not of a lack of end-organ responsiveness to CCK.  相似文献   
16.
17.
18.
19.
Polymer-associated infection is a problem of increasing importance in modern medicine. In a new approach to prevent such infections we have modified polyvinylfluoride (TEDLAR) films by graft copolymerization with N-vinylpyrrolidone to which iodine can be complexed. Grafting reaction was performed by the preirradiation technique using an electron accelerator. Grafted films were then treated in Lugol's solution for at least 24 h. Release of free iodine from the films was determined either by titration or using the agar disc diffusion test, showing an iodine release for up to 4-5 days. The antimicrobial activity of the films was tested in bacterial adhesion measurements. Bacterial and fungal cells in the range of 10(3) to 10(6) cfu/cm2 polymer were found on control samples without iodine, whereas on iodine-complexed films no viable cells could be detected at least for 5 days or even longer. Thus, microbial adhesion and growth can be inhibited by iodine-containing polymers.  相似文献   
20.
A case report of a male aged 31 who, after a journey to Bangladesh, returned with a disease resembling acute hepatitis A. Closer study revealed a hepatitis E infection. He recovered in slightly over two weeks.  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