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   21340篇
  免费   1936篇
  国内免费   48篇
耳鼻咽喉   261篇
儿科学   766篇
妇产科学   535篇
基础医学   3325篇
口腔科学   438篇
临床医学   2468篇
内科学   4225篇
皮肤病学   318篇
神经病学   1534篇
特种医学   997篇
外国民族医学   3篇
外科学   2604篇
综合类   548篇
一般理论   25篇
预防医学   2119篇
眼科学   285篇
药学   1688篇
  1篇
中国医学   6篇
肿瘤学   1178篇
  2021年   283篇
  2019年   277篇
  2018年   304篇
  2017年   218篇
  2016年   255篇
  2015年   312篇
  2014年   436篇
  2013年   680篇
  2012年   854篇
  2011年   923篇
  2010年   522篇
  2009年   435篇
  2008年   776篇
  2007年   827篇
  2006年   831篇
  2005年   816篇
  2004年   743篇
  2003年   689篇
  2002年   688篇
  2001年   627篇
  2000年   661篇
  1999年   558篇
  1998年   322篇
  1997年   282篇
  1996年   321篇
  1995年   280篇
  1994年   256篇
  1993年   249篇
  1992年   529篇
  1991年   521篇
  1990年   495篇
  1989年   474篇
  1988年   449篇
  1987年   455篇
  1986年   460篇
  1985年   449篇
  1984年   363篇
  1983年   291篇
  1982年   232篇
  1981年   200篇
  1980年   201篇
  1979年   327篇
  1978年   250篇
  1977年   234篇
  1976年   202篇
  1975年   210篇
  1974年   188篇
  1973年   191篇
  1972年   191篇
  1971年   184篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
91.
Serum concentrations of antigenic keratan sulphate determined by an enzyme linked immunosorbent assay (ELISA) with a monoclonal antibody were studied in patients with rheumatoid arthritis (RA), osteoarthritis, ankylosing spondylitis, other inflammatory diseases, and a large control group of women without arthritis. Mean keratan sulphate concentrations were low in 117 women with RA compared with 227 female control subjects matched for age drawn from a community survey. There were significant correlations between serum keratan sulphate concentrations in patients with RA and serum C reactive protein and the erythrocyte sedimentation rate. Serum keratan sulphate concentrations were also low in 29 men and women with ankylosing spondylitis and 29 patients with arthritis and high concentrations of C reactive protein. In 98 women undergoing an operation for benign breast disease there were decreases in serum keratan sulphate concentrations after the operation which correlated with doses in serum C reactive protein. No differences were found in keratan sulphate concentrations in 137 women with osteoarthritis compared with controls. Within the group with osteoarthritis there were no differences for the various joint groups and there was no obvious correlation with radiographic severity or progression. These findings suggest serum keratan sulphate is unlikely to be useful as a diagnostic marker in osteoarthritis or RA but indicate a role for inflammation in the regulation of cartilage loss.  相似文献   
92.
A prospective study was conducted to determine the frequency and distribution of bacterial and viral pathogens in infants hospitalized with suspected sepsis and to evaluate the potential of virus detection for improving patient management. A causative organism was detected in 157 (67%) of 233 previously healthy infants less than 3 months of age, who had been hospitalized for suspected sepsis: 19 (8%) had bacterial infections, 135 (58%) had viral infections, and 3 (1%) had mixed viral-bacterial infections. Viral infections occurred in a seasonal pattern: enteroviruses were responsible for most of the hospitalizations during summer and fall (65/110; 63%) and respiratory syncytial and influenza A viruses were responsible for most of the infections during winter (44/81; 55%). In contrast, bacterial infections were not seasonally distributed. Virus was detected in 33% of the 138 infected infants within 24 hours, and in 64% within 3 days. We conclude that viral infections are prevalent among infants hospitalized for suspected sepsis, and most can be detected early enough to influence patient management.  相似文献   
93.
Long-term clinical neurologic and otologic sequelae of traumatic head injury are well recognized. In this article, we describe the relationship among neurophysiologic, neuro-otologic, and neuroradiologic findings in a series of fifty patients with acute, severe head injury. Seventy percent of the patients had one or more otologic abnormalities, of which hemotympanum was most common. Outcome of computerized tomography (CT), auditory brainstem response (ABR), and otologic examination findings were not mutually dependent. For example, otologic disease was found in 50% of the patients with normal ABR. All but one patient in the series showed brain damage by CT; yet only 14% of the series had evidence of temporal bone fracture and, unexpectedly, one third of this group yielded normal otologic findings and a normal ABR. We conclude that combined application of otologic examination, CT scanning, and auditory evoked response assessment provides complementary information on structural and functional neuro-otologic status in persons with acute, severe head injury.  相似文献   
94.
95.
96.
Gastro-oesophageal reflux and intestinal malrotation in children   总被引:1,自引:0,他引:1  
In a series of 74 children undergoing Nissen fundoplication for persistent gastro-oesophageal reflux unresponsive to intensive medical treatment, there was an unexpectedly high incidence (54 per cent, n = 40) of intestinal malrotation. The series was not homogeneous, 25 of the children having reflux as a complication of a serious congenital abnormality (48 per cent incidence of intestinal malrotation), and 49 presenting with 'idiopathic' reflux (57 per cent incidence of intestinal malrotation). Intestinal malrotation is best detected pre-operatively by careful barium radiology, requiring clinicians to be aware of the association. In our experience, in children over the age of 3 months, both an antireflux operation and Ladd's procedure are often necessary to stop gastro-oesophageal reflux when an intestinal malrotation is present.  相似文献   
97.
A non-invasive cine magnetic resonance imaging (MRI) technique was developed to allow, for the first time, detection and characterization of chronic changes in myocardial tissue volume and the effects upon these of treatment by the angiotensin-converting enzyme (ACE) inhibitor captopril in streptozotocin (STZ)-diabetic male Wistar rats. Animals that had been made diabetic at the ages of 7, 10 and 13 weeks and a captopril-treated group of animals made diabetic at the age of 7 weeks were scanned. The findings were compared with the results from age-matched controls. All animal groups (n = 4 animals in each) were consistently scanned at 16 weeks. Left and right ventricular myocardial volumes were reconstructed from complete data sets of left and right ventricular transverse sections which covered systole and most of diastole using twelve equally incremented time points through the cardiac cycle. The calculated volumes remained consistent through all twelve time points of the cardiac cycle in all five experimental groups and agreed with the corresponding post-mortem determinations. These gave consistent myocardial densities whose values could additionally be corroborated by previous reports, confirming the validity of the quantitative MRI results and analysis. The myocardial volumes were conserved in animals whose diabetes was induced at 13 weeks but were significantly increased relative to body weight in animals made diabetic at 7 and 10 weeks. Captopril treatment, which was started immediately after induction of diabetes, prevented the development of this relative hypertrophy in both the left and right ventricles. We have thus introduced and validated quantitative MRI methods in a demonstration, for the first time, of chronic myocardial changes in both the right and left ventricles of STZ-diabetic rats and their prevention by the ACE inhibitor captopril.  相似文献   
98.
Our purpose was to investigate the eliciting threshold concentration of formaldehyde in formaldehyde-sensitive individuals in the occluded and non-occluded patch teat and to evaluate the relationship in repeated open application test (ROAT) with a product containing a formaldehyde releaser. 20 formaldehyde-sensitive patients and a control group of 20 healthy volunteer were included in the study. Occluded and non-occluded patch tests with formaldehyde solutions form 25 to 10,000 ppm. and ROAT for I week with a leave-on cosmetic product containing on average 300 ppm formaldehyde. Were carried out simultaneously on each subject. In the occluded patch test. 1/2 of the 20 patients only reacted to 10,000 ppm formaldehyde. 9 reacted to 5,000 ppm. 3 reacted to 1.000 ppm. 2 reacted to 500 ppm and I reacted to 25 ppm. No definite positive reactions were observed in the non-occluded patch test or in the ROAT No positive reactions were observed in the control group to any of the test procedures. We concluded that the threshold concentration for occluded patch test to formaldehyde in formaldehyde-sensitive patients was 250 ppm. The threshold in occluded patch test corresponded to the degree of sensitivity Definite positive reactions in the ROAT were not seen, either indicating that they are unlikely to happen with the type of product used or that the exposure time was too short.  相似文献   
99.
Deferred treatment for prostate cancer   总被引:2,自引:0,他引:2  
The clinical outcome of 278 prostate cancer patients managed by a deferred treatment policy was analysed retrospectively. Following TURP or biopsy, all patients were asymptomatic and deemed suitable for management by a deferred treatment policy, i.e. hormone therapy or other forms of treatment were only initiated if and when symptomatic progression occurred. The overall 5-year survival rate was 30%; 18% of patients died from other causes without needing treatment for their prostate cancer; 11% were alive and untreated after 5 years' follow-up; 17% died from prostate cancer without further treatment. Poor tumour grade, anaemia, metastatic disease, a short history, presentation with retention, and a raised serum creatinine at presentation were associated with a poor prognosis.  相似文献   
100.
OBJECTIVES: To develop an immune-competent animal model for mucosally derived squamous cell carcinoma (SCCA). STUDY DESIGN: Fifteen Fischer 344 rats were inoculated with 1, 2, 5, 10, or 20 x 10(6) FAT7 cells in their flanks. The animals were observed for tumor growth and metastasis. RESULTS: All animals developed tumors that grew exponentially. Pulmonary metastases developed in all animals and 13% developed lymph node metastases. CONCLUSION: The FAT7 flank tumor in Fischer 344 rats is a new animal model that closely resembles the behavior of human mucosal head and neck cancer. SIGNIFICANCE: The existence of an immune-competent, mucosally derived, and reliable animal model of SCCA that somewhat resembles human head and neck SCCA gives the opportunity to perform immune-modulating experiments on head and neck cancer in these animals. EBM rating: B-3.  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