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   8565篇
  免费   426篇
  国内免费   35篇
耳鼻咽喉   178篇
儿科学   203篇
妇产科学   181篇
基础医学   1743篇
口腔科学   217篇
临床医学   658篇
内科学   1543篇
皮肤病学   163篇
神经病学   783篇
特种医学   287篇
外科学   977篇
综合类   48篇
一般理论   1篇
预防医学   615篇
眼科学   183篇
药学   895篇
中国医学   32篇
肿瘤学   319篇
  2023年   81篇
  2022年   237篇
  2021年   321篇
  2020年   166篇
  2019年   219篇
  2018年   324篇
  2017年   246篇
  2016年   313篇
  2015年   317篇
  2014年   368篇
  2013年   630篇
  2012年   806篇
  2011年   807篇
  2010年   498篇
  2009年   285篇
  2008年   240篇
  2007年   258篇
  2006年   230篇
  2005年   174篇
  2004年   156篇
  2003年   140篇
  2002年   101篇
  2001年   117篇
  2000年   104篇
  1999年   119篇
  1998年   69篇
  1997年   58篇
  1996年   56篇
  1995年   66篇
  1994年   59篇
  1993年   39篇
  1992年   48篇
  1991年   50篇
  1990年   53篇
  1989年   46篇
  1988年   61篇
  1987年   60篇
  1986年   53篇
  1985年   68篇
  1984年   52篇
  1983年   63篇
  1982年   60篇
  1981年   51篇
  1980年   41篇
  1979年   46篇
  1978年   46篇
  1977年   37篇
  1976年   51篇
  1975年   41篇
  1974年   34篇
排序方式: 共有9026条查询结果,搜索用时 9 毫秒
1.
2.
An important part of fundamental research in catalysis is based on theoretical and modeling foundations which are closely connected with studies of single-crystalline catalyst surfaces. These so-called model catalysts are often prepared in the form of epitaxial thin films, and characterized using advanced material characterization techniques. This concept provides the fundamental understanding and the knowledge base needed to tailor the design of new heterogeneous catalysts with improved catalytic properties. The present contribution is devoted to development of a model catalyst system of CeO2 (ceria) on the Cu(111) substrate. We propose ways to experimentally characterize and control important parameters of the model catalyst—the coverage of the ceria layer, the influence of the Cu substrate, and the density of surface defects on ceria, particularly the density of step edges and the density and the ordering of the oxygen vacancies. The large spectrum of controlled parameters makes ceria on Cu(111) an interesting alternative to a more common model system ceria on Ru(0001) that has served numerous catalysis studies, mainly as a support for metal clusters.  相似文献   
3.
Purpose. To present a model-dependent approach for the assessment of the in vivo drug dissolution profile based on in vitrodata for the multiple unit dosage form, as an alternative to the numerical method proposed in the study by Hayashi et al, Pharm. Res. 12:1333–1337 (1995). Methods. The data for aspirin granules administered to healthy subjects obtained in the above mentioned study were re-evaluated. The subject dissolution system was considered to consist of two subsystems connected in series, i.e. the subsystem describing the gastric-emptying process and the subsystem describing the intestinal dissolution process. The frequency response method was used to model the subject dissolution system. Results. The model in vivodissolution profile of aspirin, assessed as the integral of the model weighting function of the subject dissolution system, was in agreement with the in vivo cumulative absorption profile calculated by the Wagner-Nelson method. Conclusions. Comparison of dynamic properties of the subject dissolution system with the subsystem describing the gastric-emptying process yielded quantitative confirmation of the decisive role of the gastric-emptying process in the in vivodrug dissolution after administration in the multi unit dosage form.  相似文献   
4.
5.
6.
The objectives of this study were to determine the relationship between carotid-femoral (cfPWV) and aortic pulse wave velocity (aPWV) and to compare their modulators and association with coronary artery disease (CAD). We studied 107 consecutive patients (68 men) with a mean age of 60.49+/-8.31 years who had stable angina and had been referred for coronary angiography. cfPWV and aPWV were measured simultaneously during cardiac catheterization using the Complior device and aortic pressure waveform recordings, respectively. Based on the presence or absence of significant coronary artery stenosis (CAS) patients were subdivided into a CAS+ or CAS- group. The mean values of cfPWV and aPWV were 10.65+/-2.29 m/s and 8.78+/-2.24 m/s, respectively. They were significantly higher in the CAS+ (n=71) compared with the CAS- (n=36) group and predicted significant CAS independently of cardiovascular risk factors and mean or systolic aortic blood pressure. aPWV and cfPWV were significantly correlated (r=0.70; p<0.001) but the degree of correlation differed significantly (p<0.03) between the CAS+ (r=0.74, p<0.001) and CAS- group (r=0.46, p=0.003). Age and mean aortic blood pressure were independent predictors for aPWV as well as cfPWV. In the receiver operating characteristic (ROC) analysis, aPWV and cfPWV had similar accuracy in identification of significant CAS (AUC [area under the ROC curve]=0.76 and 0.69, respectively; p=0.13). However, neither cfPWV nor aPWV was effective at differentiating the extent of CAD. In conclusion, aPWV and cfPWV are highly correlated parameters with similar determinants and comparable accuracy in predicting significant CAS. The strength of correlation between these two indices differed significantly between subjects with and those without CAS.  相似文献   
7.
Summary During studies on the helminth fauna of wolves inhabiting natural ecosystems of Poland, 86 scats were examined. All the samples were collected in the autumn of 2005. Spirocerca lupi was detected with decantation and flotation techniques. The prevalence was 2.32 %. This is the first record of the parasite from Poland and the third case of its occurrence in the wolf (Canis lupus L.) within its distribution range.  相似文献   
8.
The paper presents the results of a pilot study which involved 50 nurses from several departments of internal medicine of The State Clinical Hospital of the Collegium Medicum, Jagiellonian University in Cracow. The results are based on the Statement Response Questionnaire. They show that the most common responses of the nurses in the face of anxiety expressed by patients are cheering up the patient, collecting information about the symptom, and offering explanation of the symptom. The least common responses included expressing one's own positive emotions and showing empathy towards the patient.  相似文献   
9.
10.
A group of 50 patients with basal cell carcinoma of the face was treated by 13-cis-retinoic acid. The treatment resulted in diminution of the tumors. Complete regression was observed in 4 cases. Histological examination revealed necrosis of cancer cells and mononuclear infiltration into the treated tumors. In the group with weak clinical and histological reaction to the treatment all basal cell carcinomas were of adenoid type. A better effect was observed in the group with lower serum retinol level. This treatment method seems to be supplementary to surgery in prevention of the tumor recurrence.  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