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   57900篇
  免费   2792篇
  国内免费   363篇
耳鼻咽喉   543篇
儿科学   1155篇
妇产科学   844篇
基础医学   7398篇
口腔科学   1251篇
临床医学   3695篇
内科学   14991篇
皮肤病学   964篇
神经病学   4188篇
特种医学   2195篇
外科学   10472篇
综合类   249篇
预防医学   1691篇
眼科学   824篇
药学   3836篇
中国医学   157篇
肿瘤学   6602篇
  2023年   331篇
  2022年   678篇
  2021年   1205篇
  2020年   655篇
  2019年   868篇
  2018年   1180篇
  2017年   915篇
  2016年   1055篇
  2015年   1168篇
  2014年   1486篇
  2013年   1796篇
  2012年   2844篇
  2011年   3130篇
  2010年   1827篇
  2009年   1519篇
  2008年   2760篇
  2007年   2930篇
  2006年   2941篇
  2005年   2996篇
  2004年   3038篇
  2003年   2848篇
  2002年   2830篇
  2001年   1839篇
  2000年   1739篇
  1999年   1719篇
  1998年   791篇
  1997年   645篇
  1996年   545篇
  1995年   501篇
  1994年   472篇
  1993年   425篇
  1992年   1077篇
  1991年   1023篇
  1990年   877篇
  1989年   975篇
  1988年   826篇
  1987年   745篇
  1986年   790篇
  1985年   725篇
  1984年   482篇
  1983年   423篇
  1982年   226篇
  1981年   230篇
  1979年   327篇
  1978年   264篇
  1977年   232篇
  1975年   226篇
  1974年   198篇
  1973年   185篇
  1971年   182篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
We have evaluated the feasibility of enhancing the cytotoxic effect of cytosine arabinoside (ara-C) on acute myeloid leukemia (AML) cells by increasing the proliferative activity with hematopoietic growth factors. Leukemic cells from 8 persons with AML were tested. Preincubation with interleukin (IL)-3 (5 U/ml) for 3 days increased DNA synthesis as measured by tritiated thymidine incorporation and Ki67 expression in cells from 7 out of 8 persons with AML. Leukemic cells preincubated with IL-1 (10 U/ml) or IL-3 (5 U/ml) were subsequently exposed to ara-C (3 micrograms/ml) for the final 24 h and the activity of ara-C against clonogenic acute myeloid leukemia cells was evaluated in terms of the inhibition of colony formation in semisolid media. The exposure to ara-C inhibits the proliferation of a higher proportion of clonogenic cells in culture pretreated with IL-3 than in control or cells pretreated with IL-1. The enhanced cytotoxic effect of ara-C in the cells pretreated with IL-3 correlated with increased formation of intracellular ara-CTP. IL-3-induced recruitment of quiescent blasts into the proliferative compartment will lead to increased formation of ara-CTP in the cells, which would result in an enhanced leukemia cell kill.  相似文献   
82.
83.
84.
Endocrine tumor of the pancreas is potentially malignant. A multicenter analysis of these tumors was conducted to clarity the present status of their surgical management and the subsequent long-term surgical results. The Japan pancreatoduodenectomy (JPD) study group carried out the study; 368 patients were enrolled and variables related to tumor characteristics, surgery, and survival were retrospectively analyzed. There were 222 patients with functioning tumor and 143 patients with nonfunctioning tumor. Malignant tumor was found in 140 of 368 (38%) of the patients, and 63/140 (45%) of these patients had metastatic lesion; the most common site of the metastasis was liver 34/136 (25%), followed by regional lymph nodes 26/136 (19%). Pancreatic resection was performed in 91% of patients with nonfunctional tumor and in 83% of those with malignant tumor, and 73% of the pancreatic resections were done with lymph node dissection. The overall 5-year actuarial survival rate was 76% in patients with malignant tumor. The actuarial 5-year survival rate was 93% in the patients without metastasis and 83% in patients who received curative resection. Multivariate analysis showed that the presence or absence of synchronous metastasis was the sole significant prognostic factor. The results suggest that: (i) malignant endocrine tumor of the pancreas is a curable malignancy when pancreatic resection with lymph node dissection is adopted and (ii) that synchronous metastasis is the dominant prognostic factor. This study was carried out as a group project. The authors' institutions are as follows  相似文献   
85.
Community-acquired pneumonia is one of the major respiratory diseases causing hospital admission in previously healthy patients. Prompt and appropriate antibiotic selection is essential for recovery. The authors tried to determine the distribution of the etiologic agents of community-acquired pneumonias and to analyze predictive factors. Out of 188 cases of community-acquired pneumonia presenting to our hospital, etiologic agents were determined in 106 cases (56%). Twenty-nine cases were due to Streptococcus pneumoniae, 27 cases due to Mycoplasma, 17 cases due to Haemophilus influenzae and 21 cases due to Mycobacterium tuberculosis. M. tuberculosis was the cause in 11% of all cases and the importance of pulmonary tuberculosis must be emphasized as a community-acquired pneumonia. Out of 58 cases under 50 years old, Mycoplasma pneumoniae was the etiologic agent in 23 cases (40%) and S. pneumoniae in 7 cases (12%). Out of 62 cases not less than 70 years old. M. tuberculosis was the most common etiologic agent (15 cases, 24%). S. pneumoniae followed, being causative in 13 cases (21%). M. tuberculosis was the cause in 10 cases out of 31 cases who did not complain of fever at presentation. In 86 cases who did not show leukocytosis on admission, 21 cases were due to Mycoplasma (24%) and 15 cases were due to M. tuberculosis (17%). In particular 17 cases were due to Mycoplasma among 28 cases under 50 years old without leukocytosis (61%), and 11 cases were due to M. tuberculosis in the 27 cases no less than 70 years old without leukocytosis (41%).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
86.
We report herein a case of spontaneous subcapsular hepatic hemorrhage which occurred in a 33-year-old woman 1 day after she had been delivered of her second child by cesarean section following an uneventful pregnancy. She complained of right upper quadrant pain on the 1st postoperative day, and computed tomography (CT) showed subcapsular low-density masses in both liver lobes, while extravasation was demonstrated by CO2 intraarterial digital subtraction angiography (IADSA). The hemorrhage was successfully controlled by transcatheter arterial embolization (TAE). However, on the 3rd day after TAE, an exploratory laparotomy was performed to establish an exact diagnosis to explain the persistent abdominal pain and abnormal liver function tests. Subcapsular hematomas in both lobes were confirmed and no visible laceration was present. The patient recovered gradually by spontaneous absorption of the hematomas and was discharged on the 22nd postoperative day. Spontaneous hepatic hemorrhage associated with pregnancy is a very rare complication, and establishing a correct diagnosis and initiating appropriate therapy are essential for this life-threatening disease.  相似文献   
87.
There is no definitive surgical procedure for acquired lesions of the tricuspid valve (TV). From Feb, 1978, through March, 1990, the surgical treatment for the organic lesions of TV was performed in 10 patients, repair in 6 and TV replacement in 4. TV was repaired by commissurotomy, annuloplasty or valvuloplasty, or combination of them. When residual significant tricuspid regurgitation (TR) and/or stenosis (TS) was detected by intraoperative pulsed Doppler echocardiography after reparative procedures, TV was replaced. Follow-up periods ranged from 1 to 12 years (mean, 45.3 months). There was no early death, and late death was noted in one patient 32 months after operation. Preoperatively, 7 patients were in NYHA class IV and 3 in class III. Out of survivors, 7 are in class I and 2 in class II because of progression of mitral stenosis or coronary artery disease. Following surgery, the patients exhibited significant decrease in the cardiothoracic ratio (69.3 +/- 7.2 to 56.9 +/- 6.4%; p less than 0.01) and in the mean right atrial pressure (11.4 +/- 3.6 to 8.6 +/- 3.1 mmHg; p less than 0.05). The postoperative right ventriculography showed mild to moderate TR in 3 of 6 patients who underwent TV repair. In conclusion, TV repair could be a reasonable procedure for the organic TV lesions, although careful follow-up is recommended for residual TR.  相似文献   
88.
We analyzed the cell surface phenotype of CD8+ cells in both peripheral blood and synovial fluid (SF) of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). Utilizing the monoclonal antibodies anti-CD45RA, anti-CD29 and anti-S6F1-, one can define both suppressor effector (CD45RA+CD29-S6F1-) and killer effector (CD45RA-CD29+S6F1+) cells within the CD8 population. In patients with OA, normal proportions of CD8+CD45RA+, CD8+CD29+ and CD8+S6F1+ cells were found in both peripheral blood and SF. The peripheral blood of patients with RA, in contrast, showed a decreased percentage of CD8+CD45RA+ cells (13.4 +/- 2.6) (p less than 0.05), but a normal percentage of CD8+CD29+ and CD8+S6F1+ cells. In the SF of patients with RA, we observed a more dramatic decrease in CD8+CD45RA+ suppressor effector cells (6.4 +/- 5.0) (p less than 0.001), a significant increase in killer effector cells as measured by both CD8 + CD29+ (35.5 +/- 9.9) (p less than 0.001) and CD8 + S6F1+ cells (28.2 +/- 11.4) (p less than 0.01). These changes may contribute to the immunologic abnormalities previously noted in this disease and may provide some insight into the pathophysiologic mechanisms of RA.  相似文献   
89.
SUMMARY Weber-Christian disease, a disease of unknown aetiology, is characterised by relapsing febrile episodes and systemic panniculitis. Glucocorticoid therapy is often useful during acute phases of the disease. This report describes a patient in whom hyperpyrexia did not respond to high-dose glucocorticoid treatment, yet did respond to a non-steroidal anti-inflammatory drug (NSAID).  相似文献   
90.
Technical improvements, such as mechanical lithotripsy, stenting or nasobiliary drainage, and wire-guided cannulation, have reduced the risk of complications in endoscopic sphincterotomy. To determine the extent of this reduction in risk, we assessed the medical records of 1352 patients with common bile duct stones in whom the procedure was conducted. Complications examined were: acute cholangitis and pancreatitis. Stone clearance was achieved in 1256 patients (92.8%), with an overall morbidity rate of 7.7% and a mortality rate of 0.15%. One hundred and forty-two patients had stones with a diameter greater than 20mm; 97 of these patients did not undergo lithotripsy. Cholangitis occurred in 10 of these 97 patients (10.3%), whereas, in the 45 patients who underwent lithotripsy, there were no cases of cholangitis (P=0.02). Stone removal was not immediately accomplished or attempted in 396 patients. In 82 of these patients in whom a stent or a nasobiliary drain was placed in the common bile duct, the incidence of cholangitis was 1.2%, significantly less (P=0.045) than the incidence of 6.4% in the other 314 patients given no stenting or nasobiliary drain. To overcome difficult cannulation, precut sphincterotomy was conducted in 134 patients and wireguided sphincterotomy, a recently introduced procedure, was conducted in 55 patients. When the precutting technique was used, the incidence of acute pancreatitis was significantly higher (8/134; 6.0%) than that in the patients in whom the standard procedure was conducted, i.e., neither the precut technique nor wire-guided ES was used (23/1218; 1.9%) (P=0.008). There were no cases of pancreatitis in the 55 patients in whom wire-guided sphincterotomy was performed, although the difference was not statistically significant because of the small number of patients (P=0.06). Based on these findings, we conclude that improved technologies have led to a significant reduction of complications in endoscopic sphincterotomy.  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