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   8040篇
  免费   445篇
  国内免费   27篇
耳鼻咽喉   90篇
儿科学   126篇
妇产科学   86篇
基础医学   903篇
口腔科学   283篇
临床医学   452篇
内科学   1981篇
皮肤病学   104篇
神经病学   976篇
特种医学   376篇
外科学   1518篇
综合类   18篇
预防医学   229篇
眼科学   106篇
药学   510篇
中国医学   14篇
肿瘤学   740篇
  2023年   55篇
  2022年   80篇
  2021年   147篇
  2020年   88篇
  2019年   107篇
  2018年   150篇
  2017年   111篇
  2016年   144篇
  2015年   141篇
  2014年   187篇
  2013年   215篇
  2012年   406篇
  2011年   401篇
  2010年   241篇
  2009年   188篇
  2008年   332篇
  2007年   412篇
  2006年   380篇
  2005年   376篇
  2004年   330篇
  2003年   329篇
  2002年   346篇
  2001年   326篇
  2000年   306篇
  1999年   299篇
  1998年   95篇
  1997年   84篇
  1996年   73篇
  1995年   62篇
  1994年   56篇
  1993年   48篇
  1992年   187篇
  1991年   186篇
  1990年   156篇
  1989年   163篇
  1988年   147篇
  1987年   148篇
  1986年   162篇
  1985年   129篇
  1984年   74篇
  1983年   78篇
  1979年   63篇
  1978年   42篇
  1977年   42篇
  1974年   35篇
  1973年   37篇
  1971年   27篇
  1970年   35篇
  1969年   35篇
  1968年   27篇
排序方式: 共有8512条查询结果,搜索用时 15 毫秒
41.
A case of quadricuspid aortic valve with aortic regurgitation   总被引:2,自引:0,他引:2  
A 67-year-old man with grade 3 aortic valve regurgitation was found to have a quadricuspid aortic valve. The aortic valve consisted of 1 large, 2 intermediate and 1 small sized cusp. An accessory cusp located between the right and noncoronary cusps, and shaped like a hammock which sling by the fibrous strings originating from the both commissures to the aortic wall. Aortic valve replacement was successfully performed with a 23 mm St. Jude Medical prosthetic valve, and the patient is asymptomatic five months post-operatively. Histological examination of the resected cusps showed fibrous thickening and no rheumatic valvulitis or infective endocarditis.  相似文献   
42.
43.
Cutaneous tumour-like growths were observed on the face and other areas of the body surface of young Chilean flamingos. In the cells of these lesions, avian pox-specific cytoplasmic inclusion bodies were observed by light microscopy and virus particles were detected under an electron-microscope. It was diagnosed as avian pox.  相似文献   
44.
The present study investigated the influence of hydrostatic prssure on the exprssion of cytokines and heat shock protein 70 in a chondrocyte-like cell line. Chondrocyte-like cells (HCS-2/8) were exposed to hydrostatic pressur by a special pressure apparatus. Total RNA for cytokines (interleukin-1β, basic fibroblast growth factor, insulin-like growth factor-I, and transforming growth factor-β1) and for heat shock protein 70 was extracted and was analyzed by a polymerase chain reaction method and Northern blotting. An assay for incorporation of [35S]sulfate was performed to assess proteoglycan synthesis. The expression of transforming growth factor-β1 mRNA was enhanced after exposure to 5 Mpa of hydrostatic prssure and was reduced after 50 Mpa, whereas the expression of heat shock protein 70 was enhanced following exposure to 50 Mpa of hydrostatic pressure. The incorporation of [35S]sulfate into the cultured cells increased following exposure to 1-5 Mpa of hydrostatic pressure and decreased following 10-50 Mpa of pressure. These results suggest that hydrostatic pressure at physiologic levels enhances the expression of transforkming growth factor-β mRNA in addition to increasing proteoglycan synthesis in chondrocytes and that excessively high hydrostatic pressure reduces the expression of transforming growth factor-β1 mRNA and increases the expression of heat shock protein 79 mRNA while decreasing proteoglycan synthesis.  相似文献   
45.
To study the hemodialysis period following cadaveric renal transplantation, we reviewed 18 consecutive cadaver donor kidney pairs of which one kidney was transplanted at Shiga University of Medical Science (SUMS) while the contralateral kidney was transplanted at Kyoto Prefectural Medical University (KPMU) between January 1983 and September 1988. Of these 18 pairs, graft function was satisfactory and the recipient was free from hemodialysis in 13 pairs. However, the postoperative hemodialysis periods were different between the two centers. To clarify the factors causing this difference, recipient factors, such as age, HLA matching, total ischemic time of the graft (TIT), immunosuppression, onset of diuresis and postoperative complications were studied. There were no significant differences in age, HLA matching, or immunosuppression. TIT of cases at SUMS was significantly longer than that of cases at KPMU. The postoperative hemodialysis period at SUMS was 25.8 days and that at KPMU was 17.8 days, however, the difference was not statistically significant. The results of this study indicate that TIT seems to be a major factor relating to delayed graft function in cadaveric renal transplantation.  相似文献   
46.
Segmented cine MRI generally requires breath-holding, which can be problematic for many patients. Navigator echo techniques, particularly successful for free-breathing coronary MRA, are incompatible with the acquisition strategies and SSFP pulse sequences commonly used for cine MRI. The purpose of this work is to introduce a new self-gating technique deriving respiratory gating information directly from the raw imaging data acquired for segmented cine MRI. The respiratory self-gating technique uses interleaved radial k-space sampling to provide low-resolution images in real time during the free-breathing acquisition that are compared to target expiration images. Only the raw data-producing images with high correlation to the target images are included in the final high-resolution reconstruction. The self-gating technique produced cine series with no significant differences in quantitative image sharpness to series produced using comparable breath-held techniques. Because of the difficulties associated with breath-holding, the respiratory self-gating technique represents an important practical advance for cardiac MRI. , Inc.  相似文献   
47.
The prognostic value of prostate specific antigen was evaluated to predict disease progression after endocrine therapy in patients with prostatic cancer. A total of 73 patients was studied (6 with stage B2, 16 with stage C, 9 with stage D1 and 42 with stage D2 disease). Endocrine therapy included bilateral orchiectomy, diethylstilbestrol diphosphate and luteinizing hormone-releasing hormone analogue. Pre-treatment serum prostate specific antigen levels were determined in all patients with an enzyme immunoassay kit. During a followup of 4 to 68 months (average 24 months) clinical disease progression occurred in 24 of the 73 patients. The pre-treatment prostate specific antigen level by itself did not predict disease progression. Changes in prostate specific antigen level with treatment were correlated with the interval to disease progression in the 44 patients who had prostate specific antigen determinations at regular intervals after endocrine therapy and whose initial level was greater than 10 ng./ml. Patients who had a decrease in the prostate specific antigen levels of 80% or more within 1 month after the beginning of therapy survived significantly longer free of disease progression (p less than 0.001). Patients whose prostate specific antigen level remained elevated for more than 3 months had a high risk of disease progression within 2 years. Our study suggests that patients with the more favorable prognosis can be identified early, after 1 to 3 months of endocrine therapy, by the rapid decrease in the prostate specific antigen levels.  相似文献   
48.
The volume of the hypogastric ganglion was investigated in male, female, and prenatally androgen-exposed female newborn mice. Two milligram testosterone propionate was injected into pregnant ICR mice from days 14 to 16 of gestation. The volume of the ganglia on both sides in intact male neonates was significantly larger than that in female neonates. The volume of ganglia in testosterone-exposed females was significantly larger than those in intact females, but did not attain the male volume. In intact males, the ganglion on the left side was significantly larger than on the right. This left-right difference in the volume of the ganglia was not recognized in the intact or TP-exposed females. These results suggest that sex difference and lateralization of the volume of the hypogastric ganglion were highly dependent on the prenatal sex hormone environment.  相似文献   
49.
The possible colocalization of oxytocin (OT) and galanin (GAL) was studied by combining, on the same cryostat sections, in situ hybridization (ISH) for OT mRNA with a tritiated oligonucleotide probe and immunohistochemistry (ICC) of GAL. Many cells were either labelled by ISH (OT mRNA containing cells), or by ICC (GAL containing cells). Moreover, some magnocellular neurons in the supraoptic and paraventricular nuclei were labelled for both OT mRNA and GAL. These results demonstrate that some magnocellular neurons of the rat hypothalamus contain both GAL and OT. This approach is suitable for studying the intracellular distribution of OT gene expression and mature GAL under different physiological or experimental conditions.  相似文献   
50.
A successful case of simultaneous modified Bentall' procedure, MVR and sternoplasty was presented for a 42 years old man of Marfan's syndrome who had funnel chest, combined with mitral regurgitation, aortic regurgitation and annuloaortic ectasia. A few reports of one stage operation for the combination of funnel chest and heart disease in Marfan's syndrome has been published. A median sternotomy was made, with total cardiopulmonary bypass, heart was arrest and cor cooling hypothermia with crystalloid cardioplegic solution. Mitral valve was replaced with #31 B-S prosthetic valve. The ascending aorta proximal to the innominate artery and the aortic valve were replaced en-bloc with composite graft made of a vascular graft and aortic valve prostheses. Coronary artery orifices cut to the button-shaped, were sutured to the composite graft. Finally, sternoplasty was completed through modified Ravitch sterno-elevation. This is the first report in Japanese journals.  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