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   10534篇
  免费   518篇
  国内免费   62篇
耳鼻咽喉   92篇
儿科学   208篇
妇产科学   114篇
基础医学   1822篇
口腔科学   164篇
临床医学   585篇
内科学   2411篇
皮肤病学   213篇
神经病学   948篇
特种医学   350篇
外科学   1656篇
综合类   29篇
预防医学   293篇
眼科学   218篇
药学   799篇
中国医学   37篇
肿瘤学   1175篇
  2023年   35篇
  2022年   18篇
  2021年   139篇
  2020年   75篇
  2019年   131篇
  2018年   139篇
  2017年   131篇
  2016年   140篇
  2015年   149篇
  2014年   185篇
  2013年   282篇
  2012年   385篇
  2011年   433篇
  2010年   266篇
  2009年   234篇
  2008年   461篇
  2007年   513篇
  2006年   535篇
  2005年   608篇
  2004年   572篇
  2003年   612篇
  2002年   598篇
  2001年   359篇
  2000年   361篇
  1999年   392篇
  1998年   170篇
  1997年   149篇
  1996年   108篇
  1995年   140篇
  1994年   131篇
  1993年   131篇
  1992年   274篇
  1991年   268篇
  1990年   242篇
  1989年   236篇
  1988年   220篇
  1987年   189篇
  1986年   213篇
  1985年   164篇
  1984年   119篇
  1983年   98篇
  1982年   51篇
  1981年   41篇
  1980年   50篇
  1979年   83篇
  1978年   52篇
  1977年   35篇
  1976年   32篇
  1975年   18篇
  1969年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
International Journal of Clinical Oncology - The practice of cancer diagnosis disclosure to children has been changed with the times. The regulations of clinical trials in the 2000s might change...  相似文献   
2.
A Bochdalek hernia (BH) is a congenital abnormality with incomplete closure of the diaphragm. It is usually manifested in infants but rarely in adults. Here, we report an adult patient with gastric volvulus and giant BH that were safely repaired by endoscopic reduction and elective laparoscopic surgery, respectively. A 79-year-old woman presented with left upper abdominal pain but no history of trauma. CT revealed a giant BH with gastric volvulus. After emergency endoscopic reduction of the volvulus, elective laparoscopic repair of the BH was performed. The 8 × 8-cm defect was repaired with interrupted nonabsorbable sutures and a mesh. The patient's postoperative course was uneventful, and no complications or recurrence were observed in the 6 months that followed.  相似文献   
3.
BACKGROUND AND PURPOSETo detect areas of cerebral perfusion from bypass arteries after vascular reconstruction, we administered selective intraarterial microsphere tracer into the external carotid arteries and determined (via single-photon emission computed tomography [IA-SPECT]) whether the distribution of radiotracer matched the arteriographic distribution of contrast material as shown on external carotid angiograms.METHODSWe compared the extent of regional distribution of tracer after external carotid artery injection of 20 to 40 MBq of 99mTc-HMPAO or 99mTc-ECD with that of contrast medium on the external carotid angiograms in 582 cortical regions in 12 patients with atherosclerotic occlusive disease and in 18 patients with moyamoya disease.RESULTSMarked accumulation of tracer was found only in the expected, specific, newly developed areas of cerebral perfusion from bypass arteries. The regional distribution of tracer corresponded to that of contrast medium in 523 regions (90%) and did not correspond in 59 regions (10%). Significant overestimation of the distribution of contrast material relative to that of tracer was observed in the patients with moyamoya disease.CONCLUSIONSPECT showed slightly different distribution of tracer from that predicted by conventional angiography. IA-SPECT should enhance the analysis of newly developed areas of cerebral perfusion from the bypass arteries.  相似文献   
4.
Effect of intracoronary infusion of diltiazem (1 microgram/min) on regional myocardial blood flow (RMBF) was studied using 15-microns radioactive microspheres in 11 excised cross-circulated canine left ventricles. With total coronary blood flow (CBF) and heart rate (HR) held constant, regional ischemia was induced by ligating the left anterior descending coronary artery (LAD). Diltiazem at the dose used had no effects on ventricular Emax before and after LAD ligation. RMBF expressed by the counts divided by the counts averaged in all segments in each layer significantly (p less than 0.05) increased under diltiazem only in the low-flow region that had less than 50% RMBF before diltiazem; from 21% (+/- 12%) to 35% (+/- 18%) in the epicardial, from 22% (+/- 12%) to 32% (+/- 18%) in the midwall, and from 24% (+/- 10%) to 31% (+/- 12%) in the endocardial layers. We conclude that the beneficial effect of diltiazem on the ischemic heart involves a direct action on the coronary vascular system and does not necessarily depend on the concomitant changes in hemodynamics.  相似文献   
5.
Effects of pyrazine derivatives on the day of the first opening of the vagina in juvenile female rats were studied. Tetraethyl and 2,5-dimethyl pyrazine caused a significant delay in the first vaginal opening day of juvenile female rats, but no delay was noted in the case of 2,5-diethyl or triethyl pyrazine. These results suggest that tetraethyl and 2,5-dimethyl pyrazine cause delays in the onset of puberty in juvenile female rats.  相似文献   
6.
PURPOSE: This study evaluated the bone volume, height, and width that can be obtained in alveolar ridge augmentation using titanium mesh and autogenous bone particles in patients with cleft lip/palate. PATIENTS AND METHODS: Subjects were 15 patients with cleft lip/palate requiring tertiary bone graft for implant therapy. Computed tomography (CT) scans were taken before removing the mesh, from 1 to 21 months after bone grafting. Forty-three reconstructed images corresponding to the positions for implant placement were selected for this study. The percent defect filled with bone (%BONE), defined as the percentage of newly formed bone in the space created by the mesh, was measured for image analyses. In linear analyses, 4 parameters were used: increased bone height (IBH), percent increased bone height (%IBH), increased bone width (IBW), and percent increased bone width (%IBW). Factors influencing the quantitative data and the clinical courses of placed implants were also explored. RESULTS: The average %BONE was 91.1%. IBH averaged 4.4 mm, whereas %IBH averaged 88.5%. IBW averaged 4.6 mm, whereas %IBW averaged 86.4%. Little correlation was present between the quantitative data and patient age, or time interval. A significant correlation was identified between the data for span of the grafted area and %BONE (correlation coefficient value = -0.36). However, the diminishing rate was very low. No implants were lost postoperatively. CONCLUSIONS: Alveolar ridge augmentation with titanium mesh and autogenous bone particles from the anterior iliac crest has very high predictability as a preimplant procedure in patients with cleft lip/palate.  相似文献   
7.
Using immunoaffinity chromatography, two species of apo-AI containing lipoproteins (AILp); lipoprotein containing apo-AI and apo-AII (Lp-AI/AII), and lipoprotein containing apo-AI, but no apo-AII (Lp-AI) were isolated from 13 female patients on continuous ambulatory peritoneal dialysis (CAPD), then characterized. The results were compared with findings obtained in agematched normolipidemic (control I) and mild hypertriglyceridemic (control II) female subjects. In comparison with control I: In AILp, the levels of total cholesterol (TC), cholesteryl ester (CE) and phospholipid (PL), and the levels of apoE were significantly lower in the CAPD patients while the levels of triglyceride (TG) and apo-CIII were significantly higher in these patients. The levels of apo-AI and apo-AII did not differ between the CAPD and control subjects. In Lp-AI/AII, changes of TC, CE, PL, TG, and apolipoproteins were similar to those of AILp, except for the ratio of apo-AI/apo-AII and the level of apo-CII, which was higher in the CAPD patients. In Lp-AI, changes of TC, CE, PL, and TG were also similar to those of AILp and Lp-AI/AII, but the apo-AI level was significantly lower in the CAPD patients. In comparison with control II: In AILp, the levels of PL, apo-AI, apo-AII, and apo-E were significantly lower in CAPD patients, but the apo-CIII levels were significantly higher. In Lp-AI/AII, the levels of PL and apo-E were significantly lower in CAPD patients.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
8.
9.
10.
It is known that thromboxane A2 (TXA2) contributes to various diseases such as bronchial asthma, ischemic heart disease, cerebrovascular disorders and allergic rhinitis. A number of TXA2 synthase inhibitors and TXA2 receptor (TP receptor) antagonists have been developed to treat these diseases. Ramatroban (BAY u 3405) was developed as a potent TP receptor antagonist with excellent efficacy against allergic rhinitis in many animal models and patients. Recent studies also revealed that ramatroban can block the newly identified PGD2 receptor, chemoattractant receptor‐homologous molecule expressed on Th2 cells (CRTh2). PGD2 induces migration and degranulation of eosinophils through CRTh2 and contributes to late‐phase inflammation and cell damage. Accordingly, it was considered that ramatroban suppresses the late‐phase inflammation via TP receptor and CRTh2 blockade. In terms of the efficacy on vascular systems, it was revealed that ramatroban can suppress the expression of monocyte chemoattractant protein‐1 (MCP‐1) and adhesion molecules in endothelial cells and prevent exacerbation of inflammation by blocking these responses. According to our recent studies in hypercholesterolemic rabbits ramatroban prevents macrophage infiltration through MCP‐1 downregulation and neointimal formation after balloon injury and attenuates vascular response to acetylcholine. Therefore, ramatroban may be beneficial in the treatment of atherosclerosis.  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