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   82455篇
  免费   6426篇
  国内免费   1406篇
耳鼻咽喉   1147篇
儿科学   1419篇
妇产科学   1332篇
基础医学   12821篇
口腔科学   1280篇
临床医学   8150篇
内科学   15317篇
皮肤病学   2392篇
神经病学   6744篇
特种医学   4270篇
外国民族医学   5篇
外科学   9628篇
综合类   3005篇
现状与发展   8篇
一般理论   25篇
预防医学   5095篇
眼科学   2228篇
药学   7583篇
  15篇
中国医学   1475篇
肿瘤学   6348篇
  2023年   697篇
  2022年   1845篇
  2021年   2749篇
  2020年   1549篇
  2019年   2029篇
  2018年   2303篇
  2017年   1854篇
  2016年   2537篇
  2015年   3366篇
  2014年   4006篇
  2013年   4672篇
  2012年   6455篇
  2011年   6392篇
  2010年   3926篇
  2009年   3351篇
  2008年   4479篇
  2007年   4399篇
  2006年   3993篇
  2005年   3801篇
  2004年   3160篇
  2003年   2751篇
  2002年   2424篇
  2001年   1675篇
  2000年   1666篇
  1999年   1383篇
  1998年   637篇
  1997年   567篇
  1996年   458篇
  1995年   444篇
  1994年   375篇
  1993年   361篇
  1992年   757篇
  1991年   790篇
  1990年   667篇
  1989年   687篇
  1988年   669篇
  1987年   651篇
  1986年   565篇
  1985年   541篇
  1984年   420篇
  1983年   361篇
  1982年   272篇
  1981年   242篇
  1980年   220篇
  1979年   326篇
  1978年   273篇
  1977年   197篇
  1974年   219篇
  1973年   231篇
  1972年   184篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The relative effectiveness of intermittent infusions and primed continuous infusions of cimetidine in the maintenance of intragastric pH greater than or equal to 4.0 was evaluated in a double-blind crossover trial in 26 patients who had active or healed gastroduodenal ulcers. During the intermittent phase, each patient received 300 mg cimetidine intravenously every 6 hours. During the continuous infusion phase, each patient was given a continuous infusion of 37.5 mg cimetidine per hour, preceded by a priming dose of 300 mg cimetidine that was given for 15 minutes. Intragastric pH was monitored continuously. During the last 12 hours of the study, the continuous infusion regimen provided 20% more time in which the pH was more [corrected] than 4.0 with 25% less medication than did the intermittent infusion regimen.  相似文献   
102.
A cross-over design study was used to examine the metabolic consequences of enteral feeding for 48 to 96 hours with either a branched-chain amino acid (BCAA)-enriched (44% BCAA) or a conventional egg protein formulation in 12 severely burned adult patients. A stable isotope labeled leucine (L-1-13C-leucine) tracer approach was used to measure leucine flux and oxidation and to estimate rates of whole body protein synthesis and breakdown. Additionally, 15N2-urea and 6,6-2H-glucose were administered to assess the status of urea and glucose kinetics with these two nutritional treatments. Average patient age was 54 years, and average burn surface area was 36%. Studies were conducted at an average of 25 days postburn. Leucine flux and oxidation were significantly (p less than 0.01, by paired t-test) elevated with BCAA feeding as compared to the egg protein formulation. However, there were no significant differences in the rates of leucine incorporation into, or release from, proteins (p greater than 0.05) between the two dietary periods. Mean rates of body protein synthesis and breakdown for each diet were about twice the rates reported for healthy young adults. Apparent nitrogen balance measurements were not statistically different (p greater than 0.1) between the two diet periods. Furthermore, urea and glucose kinetics failed to show significant differences between the two diet periods. It appears from these results that the major consequences of increased intake of leucine from the BCAA formula is an enhanced rate of leucine oxidation. In conclusion, (1) the availability of BCAAs is not rate-limiting for enhanced protein synthesis in burn patients, and (2) the use of enriched BCAA formulas in burn therapy does not appear to offer advantages over a routinely used enteral egg protein formula, at least based on the present determinations.  相似文献   
103.
104.
In situ hybridization of prostate-specific antigen mRNA in human prostate.   总被引:4,自引:0,他引:4  
Prostate-specific antigen (PSA) mRNA was detected by in situ hybridization utilizing a 428 base pair [35S]-labelled cDNA probe from the 3' noncoding region of the PSA gene. Thirty six fresh surgical specimens were collected from patients undergoing radical retropubic prostatectomy for carcinoma of the prostate. Quantitative analysis of the levels of PSA mRNA in both the benign and malignant tissues was performed using an IBAS 2000 Image Analysis System. The results of this study demonstrated that there is a significant decrease in the expression of PSA mRNA in the carcinoma tissue when compared to the benign epithelium. The average binding (number of silver grains/1 x 10(4) microns. 2) for 20 specimens of malignant epithelium was 475 +/- 161 and 586 +/- 140 for 16 specimens of benign epithelium (p less than 0.05). Eleven patients had both benign and malignant tissue from the same surgical specimen available for study. From these paired specimens, the PSA mRNA expression was also significantly reduced in the malignant epithelium when compared to the benign epithelium, 445 +/- 162 and 588 +/- 135 respectively (p less than 0.005). The PSA protein was detected using a monoclonal antibody to PSA with an immunohistochemical staining technique. The PSA protein expression paralleled the expression of the PSA mRNA in the majority of the tissue sections. Many of the tumor specimens showed a heterogeneous expression of PSA, whereas all of the benign epithelium had a uniform high level of PSA expression. In conclusion, PSA mRNA and protein are located only within the glandular epithelial tissue, the expression of PSA protein parallels that of the PSA mRNA, and both the PSA protein and PSA mRNA are significantly decreased in the malignant epithelium when compared to benign prostatic epithelium.  相似文献   
105.
介入手术治疗异位妊娠12例临床分析   总被引:1,自引:0,他引:1  
目的:探索一种治疗输卵管妊娠的微创介入手术,解决因其腹腔出血不能接受保守治疗或保守治疗失败的难题。保持输卵管完整及通畅,满足有生育需求的患。方法:对12例输卵管妊娠妇女行对侧股动脉穿刺,将导管超选择插至子宫动脉以甲氨喋呤(MTX)进行灌注及明胶海绵栓塞术。结果:本组病例中,术后10dB超复查孕囊脱落、吸收消失,栓塞后盆腔活动性出血停止。结论:介入治疗宫外孕输卵管妊娠,能有效杀灭胚胎组织,栓塞破裂血管止血效果明显,且能保持输卵管通畅。  相似文献   
106.
107.
108.
109.
We present a case of benign osteoblastoma of the occipital bone. Benign osteoblastoma is an uncommon primary bone tumor, which usually involves the vertebrae and the long bones. This tumor rarely develops in the calvaria, showing a preference for the temporal and frontal bones when it does. To the best of our knowledge, this case is only the eighth reported case of benign osteoblastoma confined to the occipital bone. A 20‐year‐old male presented with a mild tender mass lesion of the occipital area, just below the lambda. Plain X‐ray films and CT scans demonstrated an osteolytic mass surrounded by the sclerotic rim within the diploic space. MRI proved to be effective for the evaluation of the intracranial and intraosseous extensions of the tumor. However, it was very difficult to formulate a differential diagnosis against other osteoblastic tumors, or osteoid osteoma, in view of its radiological appearance. The final diagnosis was obtained by careful consideration of the histopathological characteristics of the tumor combined with its clinical and radiological features. Although generally regarded as benign, a complete resection is preferred over conventional curettage as this can guard against possible recurrence and malignant transformation.  相似文献   
110.
Summary Five compounds which were identified as potential new anticancer drugs inin vitro screening with the human tumor colony forming assay were selected for further evaluation usingin vitro andin vivo models of human ovarian cancer. Three of five compounds were found to inhibitin vitro colony formation of ovarian cancer cell lines derived from both untreated and combination chemotherapy refractory patients. One compound was also found to prolong survival in a human ovarian carcinoma xenograft model system. This compound, chloroquinoxaline sulfonamide, was selected for development and has shown preliminary indication of activity in phase I clinical testing.  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