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   14194篇
  免费   1404篇
  国内免费   31篇
耳鼻咽喉   193篇
儿科学   414篇
妇产科学   324篇
基础医学   1848篇
口腔科学   430篇
临床医学   1505篇
内科学   2566篇
皮肤病学   145篇
神经病学   1106篇
特种医学   551篇
外国民族医学   1篇
外科学   2266篇
综合类   581篇
一般理论   19篇
预防医学   1475篇
眼科学   342篇
药学   952篇
中国医学   14篇
肿瘤学   897篇
  2021年   183篇
  2020年   129篇
  2019年   219篇
  2018年   255篇
  2017年   212篇
  2016年   207篇
  2015年   266篇
  2014年   304篇
  2013年   477篇
  2012年   627篇
  2011年   633篇
  2010年   446篇
  2009年   398篇
  2008年   627篇
  2007年   654篇
  2006年   618篇
  2005年   621篇
  2004年   664篇
  2003年   624篇
  2002年   569篇
  2001年   402篇
  2000年   415篇
  1999年   383篇
  1998年   201篇
  1997年   212篇
  1996年   170篇
  1995年   150篇
  1994年   127篇
  1993年   128篇
  1992年   258篇
  1991年   253篇
  1990年   270篇
  1989年   241篇
  1988年   229篇
  1987年   183篇
  1986年   242篇
  1985年   195篇
  1984年   172篇
  1983年   168篇
  1982年   130篇
  1981年   117篇
  1980年   135篇
  1979年   164篇
  1978年   144篇
  1977年   141篇
  1976年   112篇
  1975年   137篇
  1974年   144篇
  1973年   146篇
  1972年   111篇
排序方式: 共有10000条查询结果,搜索用时 71 毫秒
51.

Purpose  

An open-label Phase 1 study of recombinant prime-boost poxviruses targeting CEA and MUC-1 in patients with advanced pancreatic cancer was conducted to determine safety, tolerability and obtain preliminary data on immune response and survival.  相似文献   
52.
Background: Intervention trials with self-selected participants have shown that mailed stage-targeted print materials can increase participation in physical activity in the short term. We examined the effects of a mailed stage-targeted print intervention designed to promote physical activity, in a random sample of adults living in a regional city.Method: Participants (n = 462, 40–60 years of age) were randomly allocated to an intervention in - 227) or control group (n - 235). Measures included validated 2-week physical activity recall and stage of motivational readiness for physical activity. The intervention consisted of a single mailing of a letter and full-color stage-targeted booklets (specific to precontemplation, contemplation, preparation, and action/maintenance) 1 week postbaseline. Follow-up interviews were conducted at 2 and 6 months postbaseline.Results: After 2 months, participants in the intervention group were significantly More likely to meet the current American College of Sports Medicine/Centers for Disease Control and Prevention recommendation for sufficient physical activity than those in the control group (adjusted odds ratio [OR] - 2.40; 95% confidence interval [CI] = 1.44–3.99). After 6 months, intervention participants who reported receiving and reading the intervention materials were significantly more likely to be meeting the sufficient physical activity criterion compared with the control group (adjusted OR = 2.03; 95% Cl = 1.16–3.56).Conclusions: The stage-targeted print intervention was effective in promoting short-term increases in physical activity and was most effective for participants who recognized and used the materials. This low-cost, generalizable intervention has demonstrated potential as a practical population-based physical activity promotion strategy. Further research is required before widespread dissemination would be justified, as additional strategies may be required to ensure sustained change. This project was supported by a National Heart Foundation of Australia Research Project Grant. David Crawford was supported by a Nutrition Research fellowship from the National Heart Foundation.  相似文献   
53.
Collagens in ocular tissues.   总被引:4,自引:2,他引:2       下载免费PDF全文
  相似文献   
54.
The marine natural product, manoalide (MLD), was investigated to determine if this drug inhibited purified human synovial fluid phospholipase A2 (HSF-PLA2). Utilizing classical Michaelis-Menten kinetics, apparent Km and Vmax values for HSF-PLA2 of 1.34 mM and 0.47 mumol [3H]palmitic acid released/min/mg protein were obtained using dipalmitoylphosphatidylcholine (DPPC) as the substrate, and 38.0 microM and 18.8 mumol [3H]arachidonic acid released/min/mg protein with Escherichia coli as a natural substrate. These kinetic parameters were utilized subsequently to evaluate the inhibitory effects of manoalide on HSF-PLA2. Inhibition of HSF-PLA2 by MLD was concentration and time dependent with IC50 values of 0.2 and 0.02 microM for DPPC and E. coli respectively. Dialysis studies and examination of DPPC or E. coli hydrolysis versus enzyme concentration indicate that MLD is an irreversible inhibitor of HSF-PLA2. Substrate specificity was also examined in the absence and presence of MLD using dipalmitoylphosphatidylethanolamine (DPPE) as a substrate. MLD inhibited the hydrolysis of DPPE (greater than 90% inhibition at 2 microM), and preliminary results indicate that DPPC was more readily hydrolyzed than DPPE under the substrate conditions of the assay. While the cellular source of secreted HSF-PLA2 is unknown, these studies indicate that MLD can inactivate secreted phospholipase A2 isolated from patients with inflammatory joint disease.  相似文献   
55.
56.
57.
A follow-up study was conducted in December 1987 on all 136 women between the ages of 25 and 64 years who had been recorded as being on treatment for hypertension in the Mamre Community Health Project in December 1986. A further 136 women were randomly selected from the same age category to determine the overall prevalence of hypertension. The repeatability and validity of the 1986 project questionnaire were satisfactory. The overall prevalence of hypertension in Mamre women was 25.9% (16.1% for the age group 25-44 years and 38.4% for the age group 44-64 years). The extent of underdiagnosis of hypertension in the community on the basis of the 1986 survey was 56.8%. Despite a good reported compliance rate of 72.7%, 56.3% of hypertensives were not adequately controlled. The Mamre community presents an ideal setting for an interventive study in the management of hypertension.  相似文献   
58.
Recently, we demonstrated that neural responses within the whisker region of the primary somatosensory cortex (SIw) of rats are profoundly influenced by the spatiotemporal attributes of ipsilateral, as well as contralateral, whisker stimuli. As inactivation of one SIw eliminates in the intact SIw both ipsilaterally evoked responses and the influence of ipsilateral stimulation on contralaterally evoked activity, we proposed that interhemispheric interactions between the SIws may be important for integrating bilateral whisker information. To test whether rats can recognize the bilateral nature of a whisker stimulus, we developed a tactile discrimination task that required rats to conjointly determine distances to a left and a right discriminandum as equidistant or non-equidistant using only their facial whiskers. All rats trained in this task achieved performance levels indicative of an ability to integrate bilateral whisker information. Testing during unilateral, as well as bilateral, inactivation of the SIws indicated that rats rely on both SIws for detecting the bilateral nature of a whisker stimulus. Rats were unable to perform the task without both sets of whiskers, a fact that indicates that the whiskers (and not other modalities) were used to perform this task. The findings presented here indicate that rats can solve a task that requires the conjoint detection of left and right whisker-mediated distance information and implicate the SIws as central to this ability.  相似文献   
59.
Newer endoscopic techniques derived from percutaneous renal manipulations are well suited for endoscopic reconstruction of traumatic short total membranous urethral transections. Four men and 1 child underwent successful endoscopic membranous urethral reconstruction. All 4 men are voiding with good flow and normal control more than 1 year after any endoscopic manipulation.  相似文献   
60.
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