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   238034篇
  免费   30360篇
  国内免费   9425篇
耳鼻咽喉   1712篇
儿科学   2018篇
妇产科学   5248篇
基础医学   17024篇
口腔科学   2180篇
临床医学   20536篇
内科学   29650篇
皮肤病学   1485篇
神经病学   916篇
特种医学   8450篇
外国民族医学   253篇
外科学   36211篇
综合类   29886篇
现状与发展   38篇
一般理论   3篇
预防医学   11474篇
眼科学   115篇
药学   16907篇
  149篇
中国医学   5962篇
肿瘤学   87602篇
  2024年   750篇
  2023年   4919篇
  2022年   9730篇
  2021年   12489篇
  2020年   11574篇
  2019年   10332篇
  2018年   10022篇
  2017年   10318篇
  2016年   11223篇
  2015年   13068篇
  2014年   19203篇
  2013年   18639篇
  2012年   15504篇
  2011年   15761篇
  2010年   11889篇
  2009年   12127篇
  2008年   12439篇
  2007年   11639篇
  2006年   10486篇
  2005年   8495篇
  2004年   6881篇
  2003年   5755篇
  2002年   4924篇
  2001年   4475篇
  2000年   3736篇
  1999年   3133篇
  1998年   2658篇
  1997年   2373篇
  1996年   1910篇
  1995年   1794篇
  1994年   1530篇
  1993年   1157篇
  1992年   1014篇
  1991年   894篇
  1990年   675篇
  1989年   629篇
  1988年   537篇
  1987年   444篇
  1986年   348篇
  1985年   442篇
  1984年   350篇
  1983年   228篇
  1982年   253篇
  1981年   243篇
  1980年   202篇
  1979年   143篇
  1978年   120篇
  1977年   93篇
  1976年   84篇
  1975年   52篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
AIM: To evaluate the cause of elevated prostate-specific antigen (PSA) in patients with transrectal needle biopsy negative for prostate cancer. METHODS: Serum PSA concentration, prostate volume, and pathologic findings were examined in 223 patients with negative biopsy for prostate cancer. The degree of prostate inflammation was determined by the extent and degree of inflammation shown by biopsy specimens and is expressed as an inflammation score (range: 0-36). RESULTS: A significant correlation was found between PSA concentration and prostate total volume (P=0.0001). Prostate chronic inflammation showed no correlation with PSA concentration (P=0.485, F=0.488). After allocating patients to normal PSA (4 ng/mL) groups, we found that serum PSA concentrations in both groups were predominantly affected by prostate total volume. CONCLUSIONS: An increase in prostate volume appears to be the major contributor to a high serum PSA concentration in patients with negative biopsy for prostate cancer. However, in contrast to previous reports, there was no correlation between the degree of prostate chronic inflammation and serum PSA concentrations.  相似文献   
83.
AIM: The aim of this study was to determine the effect of intravesical EDTA instillation on the development of intravesically implanted tumor cells in normal mice. METHODS: The mouse bladder tumor (MBT-2) model was used in female C3H/eb mice to evaluate the amount of normal urothelial cell shedding, and the degree of tumor growth inhibition following intravesical EDTA instillation in comparison with phosphate-buffered saline (PBS) instillation. RESULTS: At 1 h after instillation, the number of urothelial cells aspirated was 500-1000 per PBS-treated mouse and 10,000-20,000 per EDTA-treated mouse (P < 0.00001). The bladder weight, which reflected the effect of the agent on the tumor, was similar in the untreated and PBS-treated mice (105.46 +/- 46 mg and 106.2 +/- 50 mg, respectively). It was significantly lower in the EDTA-treated mice (80.4 +/- 42 mg) (P = 0.0045). CONCLUSIONS: Intravesical administration of EDTA results in significant normal and neoplastic urothelial cell shedding. Intravesical irrigation with EDTA may prevent adherence of the malignant cells to the bladder wall following tumor resection.  相似文献   
84.
The case of a 75-year-old man with three synchronous carcinomas of the lung (large cell carcinoma, adenocarcinoma, and small cell carcinoma) is reported. This is the eighth well-documented case report in the literature; however, our case is the first to be reported with the newly described histological combination.  相似文献   
85.
This paper describes a quick procedure for cadaveric liver graft retrieval during multiple organ harvesting. The technique is based on minimal preliminary dissection, absence of in situ direct portal perfusion, and en bloc removal of the liver and pancreas, with an aortic patch encompassing the coeliac trunk and superior mesenteric artery. The results of 110 pediatric liver transplantations with 109 organs harvested using this technique are reported. There were no graft harvesting injuries. The liver graft primary nonfunction rate was 4.5% (5/110). The 3-month retransplantation rate was 10%. The actual patient survival rates were 93% at 3 months and 90% at 1 year; actual graft survival rates were 85.5% and 78%, respectively. The technique described was at least as safe as conventional procedures. A major advantage of the procedure is its flexibility, which allows for the easily combined procurement of other organs (whole pancreas and intestine).  相似文献   
86.
本文应用核苷掺入技术及电镜观察首次证实雷公藤内酯对人胃癌细胞株 FGC_(85)的杀伤作用。用药早期,细胞数,分裂指数及 DNA,RNA 合成无明显变化,但出现核仁脱粒及核仁破碎等变化;晚期,电镜观察发现细胞以凋落方式死亡,药物主要作用于间期细胞,其杀伤机构的始动环节可能与核酸代谢障碍无关。  相似文献   
87.
88.
 Hexachlorobenzene (HCB) is still frequently found at elevated levels in human adipose tissue and breast milk. As intoxication with HCB causes neurological disturbance in human beings, the purpose of the present study was to examine neurobehavioral functions in rats after pre- and postnatal exposure. Female rats were fed diets with 0, 4, 8, or 16 mg HCB/kg diet. Exposure started 90 days prior to mating and was continued throughout mating, gestation, and lactation. Thereafter, the offspring were given the same diets as their respective mothers. HCB levels were determined in the brain, the liver, and in the adipose tissue from virgin rats, dams, and the offspring. Concentrations on a lipid basis were found to decline in the order adipose>liver>brain. The exposure levels chosen did not cause gross toxic effects in dams or offspring. There were dose-related increases in liver-to-body-weight ratios in exposed dams, but not in unmated females treated alike. Behavioral testing was conducted in the offspring. Examination of open-field activity on PND 21, and of active avoidance learning on PND 90 failed to reveal significant differences between groups. Training of operant behavior started at the age of 150 days in the offspring from the control, the 8-mg group, and the 16-mg group. Animals were trained on a fixed interval schedule of 1 min (FI-1). On this schedule, responses were reinforced by a food pellet every time 1 min had elapsed after the preceding reinforcement. There were dose-dependent reductions in the post-reinforcement pause, e.g. the time between each reinforcement and the first reaction emitted after it. In addition, the index of curvature, which describes the efficiency of performance on the FI-1 schedule, was decreased in a dose-dependent fashion. Received: 12 April 1994 / Accepted: 26 June 1995  相似文献   
89.
Clusterlike Headache as a First Sign of Brain Metastases of Lung Cancer   总被引:1,自引:0,他引:1  
Dr.  J. Tajti  MD  PhD ; Dr.  K. Sas  MD ; Dr.  D. Szok  MD ; Dr.  E. Vörös  MD ; Dr.  L. Vécsei  MD  DSc 《Headache》1996,36(4):259-260
We report on a patient with clusterlike headache and multiple brain metastases of lung cancer. Initially, cluster headache was suggested clinically by characteristic symptoms without any focal central nervous system signs. However, magnetic resonance imaging demonstrated multiple brain metastases. It is possible that tumor necrosis factor may have played a role in initiating the clusterlike headache.  相似文献   
90.
The magnitude and dynamics of lung cancer incidence in Jews and Arabs in Israel between the years 1962 and 1982 were studied. In general, age-standardized incidence rates increased consistently between the years 1962 and 1976 among Jewish (24% increase) and Arab (39%) males, and to a lesser degree among Jewish females (15%). Arab females had the highest (77%) increase. From 1977 to 1982 a general decrease in incidence rates, which was largest among Arab males (19%) and females (15%), was noted. Rates among Jewish males are currently 26% higher than among Arab males, and are 162% higher among Jewish females than in Arab females. Lung cancer rates in both males and females in Istrael (Jews and Arabs) are lower than in most developed countries in the world. Among the possible reasons are differences in the population risk factors profile, availability of health care and the level of diagnosis and ascertainment of cases.  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