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   45099篇
  免费   5108篇
  国内免费   75篇
耳鼻咽喉   323篇
儿科学   1319篇
妇产科学   898篇
基础医学   6207篇
口腔科学   1230篇
临床医学   5670篇
内科学   8893篇
皮肤病学   696篇
神经病学   3613篇
特种医学   1988篇
外国民族医学   1篇
外科学   5947篇
综合类   1193篇
一般理论   26篇
预防医学   5252篇
眼科学   847篇
药学   3750篇
  1篇
中国医学   77篇
肿瘤学   2351篇
  2021年   586篇
  2020年   356篇
  2019年   642篇
  2018年   734篇
  2017年   522篇
  2016年   598篇
  2015年   708篇
  2014年   940篇
  2013年   1362篇
  2012年   1993篇
  2011年   1999篇
  2010年   1122篇
  2009年   1097篇
  2008年   1898篇
  2007年   2006篇
  2006年   1971篇
  2005年   1886篇
  2004年   1737篇
  2003年   1662篇
  2002年   1617篇
  2001年   1542篇
  2000年   1468篇
  1999年   1464篇
  1998年   604篇
  1997年   479篇
  1996年   481篇
  1995年   499篇
  1994年   439篇
  1993年   498篇
  1992年   1210篇
  1991年   1127篇
  1990年   1080篇
  1989年   1055篇
  1988年   988篇
  1987年   997篇
  1986年   997篇
  1985年   915篇
  1984年   778篇
  1983年   645篇
  1982年   430篇
  1981年   360篇
  1980年   351篇
  1979年   587篇
  1978年   491篇
  1977年   374篇
  1976年   382篇
  1974年   432篇
  1973年   400篇
  1972年   386篇
  1969年   358篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Spinal cord stimulation and the relief of chronic pain.   总被引:1,自引:0,他引:1       下载免费PDF全文
Twenty six patients who had received spinal cord stimulation for chronic pain were evaluated by videotaped structured interviews with staff not directly involved in the patients' care. In addition estimates of pain relief were obtained from clinicians involved in the patients' care and from close relatives and friends. Information about lifestyles and drug usage was also collected and correlated with pain relief. At the time of the interviews half of the patients were receiving 50% or better relief of their pain.  相似文献   
93.
Angiodysplasia of the colon was diagnosed in 31 out of 1,050 patients (3%) presenting with rectal bleeding or anaemia, among 10,000 colonoscoped at St. Mark's Hospital. The lesions were identified in 16 out of 879 (2%) patients with rectal bleeding, in 15 out of 171 (9%) patients with anaemia, and in a further three patients without features of blood loss. The angiodysplasia lesions were predominantly in the right colon (76%) and occurred with a similar frequency (12%) in the transverse and the left colon. Affected patients (59% male and 41% female) were in the older age group (53–89 years; mean age 69.5 years) but only one patient had known aortic valve disease. Angiodysplasia is an important diagnosis to consider in patients presenting with colonic bleeding or anaemia because it can be treated in the majority of cases by endoscopic electrocoagulation. However in our experience it is less common (3%) than previously suggested by other authors (40–67%). Endoscopic over-diagnosis is possible when intramucosal capillaries with no bleeding tendency on local traumatisation or biopsy are included in the diagnosis but these lesions are not true angiodysplasia.  相似文献   
94.
Between 1975 and 1 April 1986, public transport by bus in the metropolitan county of South Yorkshire, England, was increasingly subsidised. Trends in road traffic accident casualties between 1974 and 1983 in all the six provincial English metropolitan counties have been compared in order to examine the possible effect of this unique subsidy on the incidence of road traffic accident casualties. During that period the total number of casualties in South Yorkshire did not change significantly compared to the other metropolitan counties. However, the proportion of all casualties in South Yorkshire who were bus occupants did increase relative to other metropolitan counties, indicating either an increase in the amount of bus travel or a decrease in travel by other modes. There was a large increase in bus patronage in South Yorkshire relative to the other metropolitan counties, and the conclusion is that it is the transport policy in South Yorkshire which resulted in an actual increase in distances travelled by bus. Since bus is the safest form of road travel, it is concluded that the public transport subsidy in South Yorkshire has benefited the health of the local population by providing the social amenity of additional travel at the least additional health cost.  相似文献   
95.
Preoperative cytologic examinations were performed on bronchial material from 92 patients with postsurgical (pathologic) stage I (American Joint Committee) adenocarcinoma of the lung. All patients were followed up for at least 5 years or until death; thus, cases of adenocarcinoma metastatic to the lungs were virtually excluded. Only 22 patients (24%) had abnormal preoperative cytologic findings. This low cytologic sensitivity is ascribed to the small size and peripheral location of the tumors. Large lesions of high histologic grades were more likely to have positive preoperative cytologic findings than small, well-differentiated ones.  相似文献   
96.
The length of the thoracic spine was measured in chest roentgenograms of 331 children from birth to 16 years and standards for thoracic spine length in this age group were obtained.  相似文献   
97.
Aspects of humoral and cell-mediated immunity that might characterize the continuation of symptoms in 25 patients with chronic Meniere's disease were examined. We found significant elevations of both humoral and cellular immune responses to viral antigens of herpes simplex I, varicella-zoster, rubella, and cytomegalovirus. Serum immunoglobulins were quantitatively abnormal in 24 of 25 patients, without a consistent pattern. These immune responses may be linked to persistent viral infection in chronic Meniere's disease.  相似文献   
98.
The short-term albumin affinity and thrombo-resistance of a polyether polyurethane vascular graft have been improved. The method is based on the C18 alkylation of the polymer. Thrombus formation by a planimetric technique and albumin retention on wire-reinforced polyurethane tubes, both C18 alkylated and untreated, were measured in short-term (4-h) exposure at femoral arterial sites in the dog. 125I-Albumin was preabsorbed on tubes and then exposed to blood for successive 2-h periods. Albumin uptake on alkylated tubes prior to blood exposure and retention following 2 h of blood exposure were significantly greater than on controls. Following a fast desorption phase in blood, the remaining albumin was more slowly desorbed from alkylated than from control tubes. Reincubation with albumin and blood reexposure produced a similar tendency, suggesting blood conditioning does not reduce the albumin affinity-enhancing property of C18 alkylation in the short term. Blood-preconditioning experiments suggested endogenous albumin has a high affinity for the C18-alkylated surface. Scanning electron microscopic examination showed thrombus and platelet densities were higher on control than on alkylated surfaces. These results suggest in vivo albumin affinity is increased for C18-alkylated polyurethane, which may be linked to decreased thrombus formation on these surfaces.  相似文献   
99.
The effect of cirrhosis on the accuracy of ultrasonography and scintigraphy in the diagnosis of hepatocellular carcinoma (HCC) has not been established. We have therefore studied the findings on ultrasound and scintigraphy in four groups of patients. Fourteen had HCC and cirrhosis, 13 had HCC but no cirrhosis, 53 had cirrhosis but no HCC and 31 had evidence neither of cirrhotic nor malignant liver disease. The accuracies of a positive interpretation of HCC on ultrasound and scintigraphy in the absence of cirrhosis were 85% and 66% respectively (NS), but fell (significantly in the case of scintigraphy: p less than 0.05) to 80% and 31% respectively in the presence of cirrhosis (p less than 0.01). The poorer performance of scintigraphy in the presence of cirrhosis was a result both of its lower sensitivity (50% compared with 85%) and the greater frequency of false positives (28% vs 5%: p less than 0.001). The accuracy of a negative interpretation of HCC on scintigraphy in the absence of cirrhosis was 96% but fell to 84% in the presence of cirrhosis, whereas on ultrasound it remained the same (96%). In conclusion, we recommend ultrasound in preference to scintigraphy as a more accurate technique for the diagnosis of HCC in the presence of cirrhosis.  相似文献   
100.
Extradural sacral (caudal) block was performed in 17 cases (14 patients) of chronic low back pain. In each case 22 ml of a bupivacaine/methylprednisolone solution incorporating a radioopaque dye was injected over a 2-min period. Patients were randomly assigned to receive the injection in the horizontal position or with 15 degrees head-up or head-down tilt applied to the operating table. Results indicate that analgesia is usually more localised than spread of solution determined by x-ray evidence and that higher levels of analgesia are achieved in patients in the head-up position. Possible causes are the differing distribution characteristics of the constituents of the solution and the gravitational effects of posture on cerebrospinal fluid mechanics. Technical problems associated with obesity, congenital abnormalities, vascular uptake of solution, and delayed spread of the injectant due to adhesions are discussed.  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