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   81216篇
  免费   3647篇
  国内免费   527篇
耳鼻咽喉   1105篇
儿科学   1535篇
妇产科学   1178篇
基础医学   10697篇
口腔科学   1921篇
临床医学   5286篇
内科学   19876篇
皮肤病学   1532篇
神经病学   6390篇
特种医学   3035篇
外科学   14047篇
综合类   345篇
一般理论   8篇
预防医学   2510篇
眼科学   1589篇
药学   5897篇
中国医学   243篇
肿瘤学   8196篇
  2023年   417篇
  2022年   852篇
  2021年   1491篇
  2020年   769篇
  2019年   1078篇
  2018年   1424篇
  2017年   1106篇
  2016年   1367篇
  2015年   1484篇
  2014年   1914篇
  2013年   2490篇
  2012年   4011篇
  2011年   4411篇
  2010年   2524篇
  2009年   2248篇
  2008年   4165篇
  2007年   4563篇
  2006年   4518篇
  2005年   4508篇
  2004年   4557篇
  2003年   4643篇
  2002年   4577篇
  2001年   2047篇
  2000年   2121篇
  1999年   1979篇
  1998年   1203篇
  1997年   985篇
  1996年   921篇
  1995年   768篇
  1994年   703篇
  1993年   700篇
  1992年   1385篇
  1991年   1193篇
  1990年   1120篇
  1989年   1139篇
  1988年   1038篇
  1987年   997篇
  1986年   908篇
  1985年   905篇
  1984年   674篇
  1983年   536篇
  1982年   332篇
  1981年   310篇
  1980年   304篇
  1979年   554篇
  1978年   366篇
  1977年   325篇
  1975年   255篇
  1974年   258篇
  1969年   258篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
In this study, the effect of combining anti-CD4 monoclonal antibody (mAb) and cyclosporin (CyA) therapy at the time of transplantation was examined. A mouse cardiac allograft model was used. Anti-CD4 mAb administered perioperatively induces long-term survival. The addition of a short course of CyA given subcutaneously in a regimen of either a high-dose treatment or a standard dose treatment to the anti-CD4 mAb treatment protocol did not have a detrimental effect on graft survival. Despite having no significant effect on graft survival, the addition of CyA to the treatment protocol did result in a significant decrease in the level of IL-2 present in the hearts 7 days after transplantation. The decrease in IL-2 production was directly related to the presence of CyA in vivo. When CyA treatment was continued throughout the period during which unresponsiveness to the graft is induced by anti-CD4 mAb therapy, 50 % of the grafted hearts were rejected once the CyA was discontinued. In conclusion, the combined use of anti-CD4 mAb therapy and CyA did not have a negative effect on graft survival in this model when the two agents were used concurrently at the time of transplantation. Received: 2 October 1996 Received after revision: 31 January 1997 Accepted: 5 February 1997  相似文献   
52.
A 45-year-old man was referred to our department in March of 1989. Physical examination showed erythroderma, palmo-plantar hyperkeratosis, generalized lymphadenopathy, hepatosplenomegaly, and leukemic manifestation. The lymphocyte count in the peripheral blood before treatment was 1.7 × 104 cells/mm3. Atypical lymphocytes such as flower cells and lobulated cells were seen in the peripheral blood. A sample excised from a lymph node showed immunoblastic, pleomorphic T cells by a modified classification scheme of the Working Formulation. A high level of serum LDH was detected (2.1 times the upper normal limit). Anti HTLV-1 antibody was also detected in the serum. The atypical lymphocytes were positive for CD3, CD4, CD5, CD7 and HLA-DR, and negative for CD8. Thus, the clinical, pathologic and immunologic features were those of typical acute-type ATL. The patient was treated with VEPA-M for three months starting in March of 1989. Because of poor response, the patient was then treated with MACOP-B, M-FEPA, and VEPP-B for about one year from June of 1989 and has been free of disease up to the time of writing, March of 1993.  相似文献   
53.
54.
The authors applied combined depth and subdural electrodes in patients with intractable complex partial seizures to detect the precise extent of epileptic foci and functionally map speech-related areas. The medial temporal structures were explored with depth electrodes and the lateral temporal cortex with subdural electrodes. On the speech-dominant side, electrical stimulation was given to demarcate the speech-related areas in the lateral temporal cortex. Based on these data, the extent of surgical resections was tailored to include as much of the epileptogenic areas as possible while preserving the functionally essential zones of the lateral cortex. According to the range of resection, three different approaches were employed for en bloc ablation of the lateral cortex and opening of the inferior ventricle. The results thus acquired have been satisfactory in terms of seizure control and the preservation of speech function.  相似文献   
55.
1. We previously reported that angiotensin II release from the mesenteric arteries of Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) increased in a time-dependent manner as a result of the isolation of the arteries and perfusion. This phenomenon appeared to be due to the withdrawal of circulating angiotensin II (AII). 2. The purpose of the present study was to test the hypothesis that vascular AII generation may be negatively regulated by circulating AII in WKY and SHR, and to clarify the role of this vascular angiotensin II in the sustained hypertension of SHR following nephrectomy. 3. The mesenteric arteries from kidney-intact and nephrectomized WKY and SHR were perfused and the amount of AII released into the perfusate was measured. The effects of the angiotensin converting enzyme inhibitor, captopril, and the effects of supplementation of renal renin and circulating angiotensins to nephrectomized rats, by blood exchange between kidney-intact and nephrectomized rats, on AII release were examined to clarify the pathway of vascular AII generation after nephrectomy. 4. Nephrectomy caused augmentation of vascular AII release both in WKY and SHR in spite of the abolishment of circulating renin. Captopril reduced this enhanced release of AII, but blood exchange did not affect it. There was no significant difference in these responses between WKY and SHR. 5. These results suggest that WKY and SHR have in common a potent pathway for production of vascular AII in response to the withdrawal of circulating AII, although this pathway is not responsible for the sustained hypertension of SHR after nephrectomy. The precise pathophysiological role of this pathway remains to be elucidated.  相似文献   
56.
The ontogeny of the behavioral effects of acute cocaine administration and behavioral sensitization to cocaine in rat pups was investigated. Acute behavior stimulating effects of cocaine were observed in pups as young as 7 postnatal days (PND) old, although they needed a higher dose of cocaine than adult rats to evoke the same motor effects. An adult dose-response curve pattern of stereotypy and locomotion to acute cocaine treatment was observed at PND 21, and of rearing at PND 28. Rats aged PND 7, 14, 21, 28, and 56 received repeated injections of saline or cocaine (15 mg/kg) twice a day for 5 consecutive days. After a 3-week period of abstinence, sensitization to a challenge dose of cocaine was assessed. Cocaine-induced stereotyped behavior was enhanced significantly only in rats in which cocaine pretreatment was initiated on PND 21, 28, and 56, but not earlier on PND 7 and 14. Adult female rats given repeated cocaine injections on PND 56–60 showed significantly greater sensitization than males, but no such sex difference was observed in pups given cocaine repeatedly on PND 21–25 or 28–32. These results show clearly that cocaine-induced behavioral sensitization in rats occurred only when subchronic cocaine administration was commenced on PND 21 or later.  相似文献   
57.
A 72-year-old female visited our hospital with the complaint of macroscopic hematuria on Jan. 29, 1990. Cystoscopic examination revealed hematuria flowing out from the left ureteral orifice. A 1 cm mass was found in the left upper calyx by retrograde pyelography (RP). Urine cytology obtained by RP was class IIIb. Later, the mass was found in the left middle calyx by CT. Repeated RP revealed no mass and the wall of the left upper calyx was irregular. Washing cytology from the left renal pelvis was class V. Left total nephroureterectomy was performed on Feb. 2, 1990. Macroscopically, no tumor mass was apparent. Microscopically, transitional cell carcinoma in situ was widely spread from the left renal pelvis to the middle ureter. The preoperative upper calyceal mass was thought to have been a blood clot. At twelve months after the operation, there has been no evidence of tumor recurrence.  相似文献   
58.
Transrectal ultrasonotomography is useful in following patients with benign prostatic hypertrophy, because prostatic shape and weight are precisely assumed. We studied the effect of chlormadinone acetate (CMA) on benign prostatic hypertrophy. CMA (50 mg/day) was administered to 30 patients with benign prostatic hypertrophy. Weight reduction over 10% of the gland was noticed in 24 cases (80%). Mictional conditions were improved in 70% subjectively and in 71.4% objectively. However, the number of nocturia decreased in only 18.9%. Reduction rate of the weight was unrelated with the weight of prostate before administration of CMA. Duration of administration of CMA and the reduction rate were estimated. There was no definite difference in reduction rate for the first 15 months, but there was a slightly high reduction rate after administration of CMA for more than 24 months. In 3 cases, the shape and weight of prostate were studied after discontinuation of CMA. The size of prostate showed a tendency to increase gradually.  相似文献   
59.
This is a case report on a patient with double cancer of kidney and urinary bladder. The patient was a 65-year-old female, and she was admitted with the chief complaint of gross hematuria and right flank pain. After careful examinations, she was diagnosed with right nonfunctioning kidney caused by invasive bladder cancer. Computerized tomography incidentally revealed a mass in the upper pole of the left kidney. Selective left renal arteriography showed stretched arteries and irregularity and tortuosity of the smaller vessels. She was diagnosed with double cancer of bladder and left kidney. Owing to the damage of the right renal function, left partial nephrectomy, total cystectomy, right nephroureterectomy and left ureterocutaneostomy were performed. According to DMSA scintigraphy measured 15 days later, the uptake value of the left kidney was 13.25%, compared to the preoperative value of 25.62%. To date, this case is 36th reported case in Japan.  相似文献   
60.
Because of the lack of adequate strength and toughness, hydroxyapatite (HA) ceramic can not be used for a substitute for a bone and joint despite its excellent affinity for the bone. The present authors have succeeded in producing a new type of HA ceramic containing zirconia. This new ceramic material is superior to ordinary HA ceramic in quality and exceeds compact bone in bending strength and fracture toughness. The Young's modulus was about 3-4 times greater than that of compact bone. The new ceramic material contained either 1.6 or 50% of zirconia by volume and was produced using a special technique to disperse the metal dioxide. In order to assess their affinity for the bone, the new ceramic materials were implanted into rabbit femurs. Sections of the bones removed at different times after operation were prepared without decalcification and subjected to optical microscopy, scanning electronmicroscopy (SEM), and electron-probe X-ray microanalyser (EPMA). The formation of direct chemical bonds with the bone was seen without intervening membrane. Thus, the new ceramic material was shown to have an excellent affinity for the bone, comparable to that of ordinary HA ceramic.  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