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   12263篇
  免费   512篇
  国内免费   100篇
耳鼻咽喉   134篇
儿科学   287篇
妇产科学   123篇
基础医学   1458篇
口腔科学   280篇
临床医学   766篇
内科学   2970篇
皮肤病学   480篇
神经病学   1032篇
特种医学   517篇
外科学   2008篇
综合类   38篇
一般理论   2篇
预防医学   584篇
眼科学   229篇
药学   772篇
中国医学   8篇
肿瘤学   1187篇
  2023年   57篇
  2022年   149篇
  2021年   239篇
  2020年   122篇
  2019年   152篇
  2018年   211篇
  2017年   204篇
  2016年   203篇
  2015年   247篇
  2014年   302篇
  2013年   386篇
  2012年   657篇
  2011年   744篇
  2010年   407篇
  2009年   377篇
  2008年   584篇
  2007年   700篇
  2006年   699篇
  2005年   700篇
  2004年   723篇
  2003年   741篇
  2002年   716篇
  2001年   258篇
  2000年   238篇
  1999年   230篇
  1998年   174篇
  1997年   141篇
  1996年   141篇
  1995年   142篇
  1994年   111篇
  1993年   99篇
  1992年   179篇
  1991年   168篇
  1990年   164篇
  1989年   171篇
  1988年   145篇
  1987年   126篇
  1986年   120篇
  1985年   165篇
  1984年   86篇
  1983年   63篇
  1982年   43篇
  1981年   40篇
  1979年   58篇
  1978年   38篇
  1975年   36篇
  1974年   43篇
  1973年   43篇
  1972年   54篇
  1969年   37篇
排序方式: 共有10000条查询结果,搜索用时 19 毫秒
21.
The authors reported the first case of acute spinal epidural hematoma (SEH) developed after open heart surgery. The patient was noticed that her legs felt weak and numb on the first postoperative day evening. On the next day morning, neurological examination revealed that flaccid paralysis of both legs and also loss of all sensory perception below the level of Th-6 spine bilaterally. The prolonged effect of anesthesia and painless onset made delayed recognition of the lesion. SEH (Th5-7) was diagnosed with MRI and decompressive surgery was immediately done, sixty hours after the beginning of cardiac operation. But in this case neurological deficits were not changed. We concluded that a routine diagnostic approach was very important procedure to find out this serious complication for all patients underwent open heart surgery in early period of its onset.  相似文献   
22.
23.
We report the case of a 67-year-old woman with severe hypertension caused by an extra-adrenal pheochromocytoma. The tumor was detected by 131I metaiodobenzylguanidine scintigraphy and it was found to be small (2 cm ?) by enhanced CT. After the extirpation of the tumor, the blood pressure of the patient immediately normalized. It should be taken into account that a small extra-adrenal pheochromocytoma can be one of the causes of secondary hypertension in elderly patients. Since small extra-adrenal pheochromocytomas are difficult to detect, it is also important to perform suitable examinations to establish the diagnosis. Furthermore, we emphasize the importance of an accurate diagnosis in elderly patients with pheochromocytoma, for they often have less symptomatology and more severe cardiovascular complications due to refractory hypertension than younger patients.  相似文献   
24.
A 66-year-old woman time of 10 days. One month after radicalmastectomy, there was local recurrence, followed by multiplepulmonary metastases, and the patient died of respiratory failure5 months after surgery. The gray-white-colored tumor measured13x12x;10 cm, and its border was well defined. The tumor wascomposed of diffusely growing round or polygonal cells withvesicular nuclei, prominent nucleoli, and ample cytoplasm containingeosinophilic inclusions. Lymph node involvement was widespread.Both vimentin and keratin were clearly demonstrated by immunohistochemicalstaining. Ultrastructural studies revealed that the MRT cellscontained cytoplasmic whorls of intermediate filaments.  相似文献   
25.
26.
T Matsukura  T Iwasaki  M Kawashima 《Virology》1992,190(1):561-564
In a plantar cyst composed of the wall of the squamous cell layer and the horny inner substance in the lower dermis, we found characteristic pathological changes, such as cytoplasmic eosinophilic inclusions and vacuolated structure, and, immunohistochemically, the papillomavirus capsid antigen. The human papillomavirus (HPV) DNA cloned from the cyst showed no homology with other known prototypes of HPV (HPV 1 through HPV 59) by Southern blot analysis under stringent conditions and was named as HPV 60. HPV 60 DNA was found in three other cases of plantar cyst with the identical pathological changes, but not in a plantar cyst without such changes. The results suggest that HPV 60 has unique biological properties to induce a plantar cyst as a distinct type of cutaneous HPV.  相似文献   
27.
We examined the effects of angiotensin II (Ang II) on inward rectifier K+ currents (IK1) in rat atrial myocytes. [125I]Ang II-binding assays revealed the presence of both Ang II type 1 (AT1) and type 2 (AT2) receptors in atrial membrane preparations. Ang II inhibited IK1 in isolated atrial myocytes with an IC50 of 46 nmol/l. This inhibition was abolished by the AT, antagonist RNH6270 but not at all by the AT2 antagonist PD123319. Treatment of cells with pertussis toxin or a synthetic decapeptide corresponding to the carboxyl-terminus of Gialpha-3 abolished the inhibition by Ang II, indicating the role of a Gi-dependent signaling pathway. Accordingly, Ang II failed to inhibit IK1 in the presence of forskolin, dibutyryl-cAMP or protein kinase A catalytic subunits. In spite of the increased binding capacities for [125I]Ang II, Ang II failed to affect IKI in cells from spontaneously hypertensive rats (SHR). AT, immunoprecipitation from atrial extracts revealed decreased amounts of Gialpha-2 and Gialpha-3 proteins associated with this receptor in SHR as compared with controls. The reduced coupling of AT, with Gialpha. proteins may underlie the unresponsiveness of atrial IK1 to Ang II in SHR cells.  相似文献   
28.
From December 1980 to December 1990, ten patients, 9 male and 1 female, ranging in age from 21 to 68 years, were operated on for aortic valve insufficiency associated with an aneurysm of the ascending aorta. The surgical treatment in all cases consisted of total replacement of the ascending aorta with Bentall's procedure (n = 4), or Cabrol's procedure (n = 6). In 5 patients an uncomplicated annulo-aortic ectasia existed. Three of them had annulo-aortic ectasia with an aortic dissection. One had aortitis syndrome, and one had syphilitic aortitis. The operative mortality for the entire group was 0% (0 death). Hospital survivors revealed satisfactory clinical improvement in NYHA class (mean value: 3.2 to 1.0). Late complications developed in 2 of the 10 patients. They had a picture of pseudoaneurysm formation at the anastomoses between the graft and the right coronary 46 months and 15 months, respectively, after the initial operation. Despite the reoperation, one died of hepatic failure 30 days after the operation, and the other died of postoperative bleeding at the anastomosis sites. We, furthermore, considered the difference in aortic cross clamp time and cardiopulmonary bypass time between Bentall's procedure and Cabrol's procedure. Aortic cross clamp time and cardiopulmonary bypass time were significantly shorter in Cabrol's procedure than in Bentall's procedure, if a probability value less than 0.20 was considered to be of statistical significance. We were able to conclude that the treatment of aortic valve regurgitation associated with an aneurysm of the ascending aorta by insertion of a composite graft is a reliable method with low operative mortality and excellent long term results, especially in Cabrol's procedure.  相似文献   
29.
Circulating serum sialyl Tn (STN) antigen levels were measured in 89 patients with epithelial ovarian cancer, 157 benign disease, and in 126 healthy controls. Serum antigen levels were increased in 48.3% of patients with ovarian cancer. The false positive rate is significantly low (4.0% in healthy controls and 9.6% in benign disease). The levels of STN antigen were significantly higher in sera of patients with cancer than in those in benign and healthy controls (p less than 0.05). The rise in serum STN antigen levels correlated to the size of the primary tumors. Of the histological type, it is interesting to note the high sensitivity in mucinous-type ovarian cancer. Survival at 1, 2, 3, 4 and 5 years for patients with STN-negative (serum STN levels less than 50 U/ml) versus STN-positive (serum STN levels greater than or equal to 50 U/mol) was 96.2, 92.3, 86.5, 82.7, and 76.9% versus 59.5, 29.7, 18.9, 10.8, and 10.8%, respectively (p less than 0.05). The overall survival probability was worse in patients with STN-positive sera. Percent progression-free survival at 1, 2, 3, 4 and 5 years for patients with STN-negative versus STN-positive was 90.4, 86.5, 76.9, 59.6, and 51.9% versus 35.1, 16.2, 8.1, 8.1, and 5.4%, respectively (p less than 0.05). The overall progression-free period of survival was shorter in patients with STN-positive sera. Multivariate regression analysis revealed that positive STN, stage, PS and histologic grade were the four variables of most importance in predicting survival. These results indicate that a positive STN antigen level in sera is an independent predictor of poor prognosis in ovarian cancer.  相似文献   
30.
The risk of cerebral infarction (CI) in an individual is dependent on the interplay between genetic risk factors and environmental influences. Binding of thromboxane A2 (TXA2) to its receptor (TP) modulates thrombosis/hemostasis and plays a significant role in the pathogenesis of CI. The aim of the present study was to investigate the relationship between human TP gene single nucleotide polymorphisms (SNPs) and haplotypes and CI in a Japanese population. A genetic association study was performed in 194 CI patients and 365 non-CI subjects by specifically characterizing 6 SNPs in the human TP gene (rs2271875, rs768963, rs2238634, rs11085026, rs4523 and rs4806942). Analysis demonstrated that there were significant differences in the overall distribution of genotypes and dominant or recessive models of rs2271875 and rs768963 between the CI and the non-CI groups. Multiple logistic regression analysis revealed that the C allele of rs768963 was significantly associated with CI (p = 0.029), even after adjusting for confounding factors (odds ratio: 2.41). Further, the C-T-C haplotype of rs768963-rs2238634-rs4806942 was significantly more frequent in the CI group (23.0%) than in the non-CI group (17.7%). These results suggest that specific SNPs and haplotypes may have utility as genetic markers for the risk of CI and that TP or a neighboring gene is associated with the increased susceptibility to CI.  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