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   25959篇
  免费   1222篇
  国内免费   218篇
耳鼻咽喉   225篇
儿科学   623篇
妇产科学   219篇
基础医学   3243篇
口腔科学   407篇
临床医学   1590篇
内科学   7253篇
皮肤病学   396篇
神经病学   1762篇
特种医学   1024篇
外科学   4555篇
综合类   101篇
预防医学   655篇
眼科学   332篇
药学   1555篇
中国医学   41篇
肿瘤学   3418篇
  2023年   194篇
  2022年   374篇
  2021年   667篇
  2020年   345篇
  2019年   503篇
  2018年   628篇
  2017年   493篇
  2016年   654篇
  2015年   658篇
  2014年   894篇
  2013年   1017篇
  2012年   1647篇
  2011年   1843篇
  2010年   1024篇
  2009年   862篇
  2008年   1516篇
  2007年   1697篇
  2006年   1709篇
  2005年   1705篇
  2004年   1640篇
  2003年   1571篇
  2002年   1494篇
  2001年   348篇
  2000年   264篇
  1999年   314篇
  1998年   369篇
  1997年   293篇
  1996年   275篇
  1995年   217篇
  1994年   198篇
  1993年   183篇
  1992年   185篇
  1991年   176篇
  1990年   155篇
  1989年   138篇
  1988年   137篇
  1987年   105篇
  1986年   107篇
  1985年   115篇
  1984年   85篇
  1983年   64篇
  1982年   54篇
  1981年   47篇
  1980年   34篇
  1979年   33篇
  1978年   34篇
  1977年   36篇
  1975年   29篇
  1973年   27篇
  1968年   38篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
A rare case of jejunal carcinoma coexisting with adenoma, situated 120 cm distal to the ligament of Treitz in a 53 year old male, is reported herein. We also review cases of adenoma and carcinoma in the jejunum and ileum from the Japanese literature, and discuss the histogenesis of carcinoma of the jejunum and ileum.  相似文献   
32.
Magnetic resonance cholangiopancreatography (MRCP) was performed in 35 patients to evaluate the feasibility of its use as a postsurgical imaging technique after resection of the pancreas. The surgical procedures performed were: pancreatoduodenectomy in 22 patients, segmental pancreatectomy in 1, distal pancreatectomy in 7, and pyroluspreserving pancreatoduodenectomy in 5. The pancreatic duct was shown in its entirety in 24 of the 35 patients (68.6%) and was partially visualized in 8 patients (22.9%), but the intrahepatic and extrahepatic bile ducts were visualized completely in all patients. Furthermore, MRCP was able to demonstrate lesions in 3 of 6 patients who had shown clinical evidence of recurrence. The visualization of the pancreatic and bile duct system was satisfactory despite anatomical changes brought about by resection of the pancreas. Thus, we conclude that MRCP is an appropriate follow-up screening test for patients with suspected abnormalities of the biliary and pancreatic duct system.  相似文献   
33.
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   
34.
Abstract: The behavioral effects of ceroid-lipofuscin accumulation, induced by intraperitoneal administration of acetyl-ethyl-tetramethyl-tetralin (AETT) in Wistar rats for 3 months, were examined in the present studies. A significant increase in neuronal ceroid-lipofuscin was demonstrated neuropathologically as well as morphometrically. Although the AETT-intoxicated rats showed neither alteration of locomotor activity nor shock sensitivity, a significant impairment of learning ability, especially an acquisition trial in passive avoidance tests, was observed. Results of the present studies indicate the possibility that a diffuse lipofuscin accumulation causes a learning impairment in rats. The results also imply the possibility of a significant role of age-related lipofuscin accumulation in the dementing processes of human especially in the elderly.  相似文献   
35.
Between November 1986 and April 1989, 101 patients with superficial bladder cancer were treated with intravesical instillations of mitomycin C on day 1 and doxorubicin on day 2 of each week for 5 consecutive weeks. Of 61 complete responders, 23 patients with carcinoma in situ and 28 with papillary cancer were randomly assigned to a non-maintenance group or to a group receiving maintenance therapy consisting of monthly instillations of the same drugs for 12 months. The 2-year non-recurrence rate calculated for patients with carcinoma in situ was significantly better in the maintenance group than in the non-maintenance group. A similar tendency was observed for patients with papillary cancer, although the difference was not significant. Side effects were considerable, with moderate to severe bladder irritation occurring in approximately half of the patients. In addition to our previous findings, the present results indicate that this intravesical combination chemotherapy is effective in eliminating superficial bladder cancers and that since the effect is not durable, even in complete responders, maintenance therapy is necessary to reduce subsequent tumor recurrence.Presented at the 4th International Conference on Treatment of Urinary Tract Tumors with Adriamycin/Farmorubicin, 16–17 November 1990, Osaka, Japan  相似文献   
36.
In the medical field, Korotkoff sounds have been explained as sounds generated by the disturbed blood flow in the artery. However, in the biomechanics field, Korotkoff sounds are considered to be produced and/or modified by the self-excited oscillation of a collapsed artery. The self-excited oscillation is an oscillation of the arterial wall. In addition, it is influenced by the nonlinear pressure–flow relationships in the artery and the arterial compliance. In this paper, we proposed an arterial-compliance-measuring method, using Korotkoff sounds. We constructed a circulatory simulator with a brachial model that mimics the physiological circulation, because in vivo resolution of nonlinear pressure–flow relationships is very difficult. The simulator was utilized to generate artificial Korotkoff sounds similar to those in auscultation in the brachial model. Additionally, we prepared latex tubes as artificial brachial arteries. In the experiment, we investigated the relationship between the self-excited oscillation and Korotkoff sounds by the distinguishing its frequency characteristics. The frequency of the sounds was changed by the variation of the tube compliance. As a result, we have found that the changes of the sounds largely depended on the difference of the tube compliance in this simulator. In conclusion, Korotkoff sounds contain useful information for predicting brachial arterial compliance. These experiments indicate the effectiveness of noninvasive measurement for brachial arterial compliance using Korotkoff sounds.  相似文献   
37.
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   
38.
Palmar advancement flap with V-Y closure for thumb tip injuries   总被引:1,自引:0,他引:1  
The palmar advancement flap with V-Y closure was used in two patients with thumb tip injuries. This technique allows more distal advancement of the flap than does a conventional palmar advancement flap and does not require skin graft coverage.  相似文献   
39.
Primary extranodal malignant lymphoma frequently occurs in the gastrointestinal tract; however, it is rarely encountered in the rectum. We report herein the case of an 85-year-old man who underwent abdominoperineal resection for primary malignant lymphoma of the rectum, and 1 year later, developed hematemesis caused by gastric metastasis. To our knowledge this is the first case report of such distant metastasis developing from malignant lymphoma of the rectum.  相似文献   
40.
PURPOSE: The association of BRCA2 polymorphisms at codon 372 [Asn (N)/His (H)]and codon 784 [Met (M)/Val (V)] with breast cancer risk was evaluated in Japanese women. In addition, the prognostic significance of these polymorphisms was studied in breast cancer patients. EXPERIMENTAL DESIGN: A case-control study was conducted to examine the association of the BRCA2 N/H372 polymorphism and M/V 784 polymorphism with breast cancer risk (cases = 149, controls = 154). The prognostic significance of these polymorphisms was evaluated in 139 patients with primary breast cancer. RESULTS: No significant association was observed between the N/H372 polymorphism and breast cancer risk. In contrast, a significant increase in breast cancer risk (odds ratio, 2.03; 95% confidence interval, 1.07-3.87) was observed in carriers of the variant allele (V784) of the M/V784 polymorphism as compared with noncarriers after adjustment for the classical risk factors, age, family history, parity, body mass index, and so forth. Among breast cancer patients, various clinicopathological parameters including menopausal status, tumor size, lymph node status, histological grade, and estrogen-receptor status were not significantly different between the carriers and noncarriers of the variant allele with regard to both N/H372 and M/V784 polymorphisms. The N/H 372 polymorphism was not significantly associated with patient prognosis. On the other hand, breast cancer patients carrying the variant allele of M/V784 polymorphism showed a significantly (P = 0.014) lower 3-year disease-free survival rate (63%) than noncarriers (92%). Multivariate analysis has revealed that the M/V784 polymorphism is a significant prognostic factor, being independent of the other conventional prognostic factors such as lymph node status and estrogen receptor status. CONCLUSION: These results suggest that the M/V784 polymorphism, but not the N/H372 polymorphism, would be useful in the selection of women at high risk for developing breast cancer and would also serve as a clinically useful prognostic factor in breast cancer patients.  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