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   13927篇
  免费   696篇
  国内免费   67篇
耳鼻咽喉   144篇
儿科学   361篇
妇产科学   189篇
基础医学   1753篇
口腔科学   446篇
临床医学   905篇
内科学   3406篇
皮肤病学   230篇
神经病学   991篇
特种医学   562篇
外科学   2481篇
综合类   80篇
一般理论   1篇
预防医学   357篇
眼科学   200篇
药学   1038篇
中国医学   70篇
肿瘤学   1476篇
  2023年   83篇
  2022年   171篇
  2021年   288篇
  2020年   153篇
  2019年   209篇
  2018年   278篇
  2017年   220篇
  2016年   284篇
  2015年   271篇
  2014年   342篇
  2013年   436篇
  2012年   642篇
  2011年   701篇
  2010年   401篇
  2009年   348篇
  2008年   590篇
  2007年   694篇
  2006年   679篇
  2005年   672篇
  2004年   695篇
  2003年   648篇
  2002年   705篇
  2001年   461篇
  2000年   463篇
  1999年   390篇
  1998年   207篇
  1997年   149篇
  1996年   139篇
  1995年   126篇
  1994年   114篇
  1993年   96篇
  1992年   361篇
  1991年   300篇
  1990年   258篇
  1989年   279篇
  1988年   230篇
  1987年   205篇
  1986年   181篇
  1985年   203篇
  1984年   154篇
  1983年   103篇
  1979年   72篇
  1977年   52篇
  1975年   44篇
  1974年   51篇
  1973年   50篇
  1971年   46篇
  1970年   43篇
  1969年   49篇
  1968年   45篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Bropirimine [2-amino-5-bromo-6-phenyl-4-(3H)-pyrimidinone] is a low-molecular-weight compound that acts as an inducer of interferon in several animal species. Experiments were designed to explore the possibility of using this drug for the treatment of renal-cell carcinoma (RCC). Euthymic BALB/c mice were inoculated with murine RCC (Renca) cells and given graded doses of Bropirimine p.o. for 5 consecutive days beginning on day 1 following tumor inoculation. These mice were killed and tumors were excised on day 21. Bropirimine significantly (P<0.01) inhibited the tumor growth at a daily dose of 1,000 or 2,000 mg/kg. No adverse effect or toxicity was noted at 1,000 mg/kg, and at 2,000 mg/kg there was only a marginal body-weight reduction without any other appreciable side effect. In addition to the inhibition of tumor growth, there was a small yet significant (P<0.05) increase in the duration of survival (in days) in the Bropirimine-treated animals. When the treatment was delayed to begin on day 6 following tumor inoculation, Bropirimine did not suppress tumor growth in euthymic mice, pointing to the importance of the timing of the treatment. In athymic nude BALB/c mice lacking T-cells or T-cell function, Bropirimine also inhibited tumor growth (P<0.01). The antitumor effect of this drug was abolished by pretreatment with anti-asialo GM1 serum, which eliminated natural killer (NK) activity in euthymic mice. In vivo treatment with Bropirimine augmented the cytotoxicity of lymphocytes isolated from the spleens or lungs of the tumor-bearing mice, which were active against Renca and YAC-1 cells in vitro. This activity was NK-cell-dependent as judged on the basis of the results of the in vitro complement-dependent cytotoxicity assay. Since Bropirimine induced interferon (IFN)-/ production, significantly (P<0.05) elevating its serum concentration, and since this drug mimics the effects of IFN-/, it seemed likely that the Bropirimine-induced NK cell augmentation we found was mediated by IFN-/. These results suggest that Bropirimine, a booster of NK activity, may have potential as an adjunct to other therapeutic modalities in the treatment of human RCC.  相似文献   
102.
Immunostaining of the proliferating cell nuclear antigen (PCNA) provides important information about cell kinetics and is easily performed on routinely obtained formalin-fixed, paraffin-embedded materials. We report herein the results of a retrospective study on PCNA staining in esophageal cancer undertaken to determine its significance. As this study indicated that immunoreactivity was preserved in specimens fixed within 24 h, only 31 specimens from surgical patients were available for this investigation. The mean PCNA index of the patients without invasion to the adventitia (35.7±17.9) was significantly lower than that of those with invasion to the adventitia or neighboring structures (49.7±14.5), while the PCNA index did not correlate with other clinicopathologic parameters such as histologic type, lymph node metastases, or prognosis. However, when an analysis of PCNA staining was combined with an analysis of argyrophilic nucleolar organizer region (AgNOR) staining, a correlation with prognosis was found. In fact, seven patients with a high PCNA index (44) and AgNOR count (6) had a significantly poorer prognosis than the remaining 22 (P=0.0014), and six of these seven patients died within 2 years. These results indicate that this combined evaluation may be useful for the identification of patients with a poor prognosis among those undergoing surgery for esophageal squamous cell carcinoma.  相似文献   
103.
We herein report a case of renal cell carcinoma coexisting with malignant lymphoma. A 69-year-old male complained of an obstruction of the right nasal cavity due to a solid tumor in the paranasal sinuses. A biopsy of the tumor revealed diffuse, large cell and B cell type non-Hodgkin lymphoma. At the same time, just before the patient was scheduled to receive therapy, a left renal cell carcinoma was found. He therefore underwent a left radical nephrectomy.  相似文献   
104.
We experienced two patients with single coronary artery who underwent CABG using arterial grafts successfully. In two patients coronary angiography demonstrated a single coronary artery which was originated in left coronary sinus and was bifurcated to LAD and LCx, and then RCA branched off proximal LAD, passing in front of the right ventricular out flow tract (Sharbaugh Type L-IIa). To the first patient, a 52-year-old man who had angina on exertion due to long stenosis of RCA, CABG to RCA using RITA was carried out. To the second patient, a 57-year-old man who had inferior myocardial infarction due to 90% stenosis of proximal LAD, CABG to RCA using RITA and LAD using LITA was carried out. Single coronary artery without additional congenital cardiac anomalies may lead to myocardial ischemia, necessitating CABG as coronary reconstructions.  相似文献   
105.
A 42-year-old woman with history of chest blunt trauma from an automobile accident 250 days earlier had suffered easy fatigability of the right upper extremity. She had difference of blood pressure between upper extremities, 94/60 mmHg in the right and 126/70 mmHg in the left. Chest CT showed dilation of the innominate artery which compressed the trachea. Aortography showed an aneurysm of the innominate artery and occlusion of the right subclavian artery at its origin. The aneurysm of the innominate artery was resected and replaced with a 6 mm Dacron graft with aid of the external shunt. The right subclavian artery was also reconstructed with same graft. The aneurysm of the innominate artery should be suspected as a rare complication in blunt trauma of the chest.  相似文献   
106.
A 41-yr-old patient with non-insulin-dependent diabetes mellitus (NIDDM), before and after ABO-incompatible renal transplant, is reviewed using serial protocol biopsy. Although she recovered from delayed hyperacute rejection (DHAR) immediately post-transplantation, her graft function deteriorated gradually. A mild acute transplant glomerulitis, noted at the 155th day post-transplantation, progressed to pronounced chronic transplant glomerulopathy over 5 yr. In the specimen of the last biopsy, at 5 yr post-transplantation, glomeruli demonstrated an exudative hyaline lesion, which was characteristic of diabetic nephropathy in addition to chronic transplant glomerulopathy. Therefore, we made a diagnosis of this glomerular lesion as chronic transplant glomerulopathy complicated by diabetic glomerulopathy. Considering the result of this case, the protocol biopsy is a useful procedure to diagnose an accurate cause of graft dysfunction in individual cases. It is concluded that the protocol biopsy is apparently useful for the detection of various pathological processes occurring in allograft and may contribute to a strategy for improvement of graft survival.  相似文献   
107.
In order to elucidate temporal changes in airway reflex responses to prolonged tracheal intubation, 14 patients anaesthetized with sevoflurane were studied. In each spontaneously breathing patient with an endotracheal tube in place, the end-tidal concentration of sevoflurane was slowly decreased from the initial value of 1.3% until signs of airway irritation were observed. The value of end-tidal sevoflurane concentration at which the airway reflexes occurred (T(ar)) and the types of airway reflex response elicited at onset of airway reflex response were determined during the periods immediately before (presurgical period) and after surgery (post-surgical period), with an interval ranging from 2 to 7 h between the two periods. There was no significant difference in the values of T(ar) between the presurgical period (0.6 +/- 0.3%, mean +/- SD) and the post-surgical period (0.7 +/- 0.1%). There was a considerable difference in the type of airway reflexes elicited during the two different periods; the initial responses during the presurgical period were the apnoeic reflex and/or forceful expiratory efforts, whereas the initial response during the post-surgical period, in the majority of patients, was the swallowing reflex. Our results indicate that there may be adaptation mechanisms responsible for temporal changes in airway protective reflexes after prolonged endotracheal intubation in surgical patients.  相似文献   
108.
Following the successful introduction of laparoscopic cholecystectomy, many reports confirming the feasibility of using laparoscopy for bowel resection and predicting that it would be advantageous in terms of its minimal invasiveness have been published. In the context of cancer treatment, however, the feasibility of lymphadenectomy, the risk of recurrence, and survival have emerged as major concerns. Even though mucosal cancer (Tis) can be treated by endoscopic resection (ER), when this is not possible open surgery (OS) must be performed. In patients with T1 cancer, tumors showing slight submucosal layer invasion (sm 1) can be treated in the same way as Tis (in cancer) cancers. But 5% to 10% of patients with T1 cancer have massive submucosal layer invasion (sm 2-3) with paracolic lymph node metastasis. At least partial bowel resection with paracolic lymphadenectomy is considered necessary for T1 (sm 2-3) cancers in principle. In summary, laparoscopic local excision of Tis cancers that are endoscopically unresectable and laparoscopically assisted partial resection with paracolic lymphadenectomy for T1 cancers have become accepted because local excision and partial resection with paracolic lymphnedectomy are fairly simple to perform laparoscopically. Therefore as a strategy for the treatment of early colorectal cancer (CRC), minimally invasive laparoscopic bowel resection (LBR) has been positioned between endoscopic resection (ER) and open surgery (OS). While the difficulty of performing radical lymphadenectomy is considered one of the greatest obstacles to the introduction of laparoscopic bowel resection (LBR) for the treatment of advanced colorectal cancer (CRC), early colon cancer is a good indication for laparoscopic bowel resection.  相似文献   
109.
A neonate presented with Dandy-Walker syndrome manifesting as a large posterior cranial fossa cyst, aplasia of the lower cerebellar vermis, and elevation of the confluence of the sinuses but without hydrocephalus. A cystoperitoneal shunt was placed at one month after birth. The cyst diminished in size, and marked development of the cerebellar hemispheres and descent of the confluence of sinuses were observed, but not vermis development. The primary pathology of Dandy-Walker syndrome is posterior cranial fossa cyst formation due to passage obstruction in the fourth ventricle exit area and aplasia of the lower cerebellar vermis. The first choice of treatment in patients with Dandy-Walker syndrome in whom the cerebral aqueduct is open is cystoperitoneal shunt surgery, regardless of the presence or absence of hydrocephalus.  相似文献   
110.
Ca2+/calmodulin-dependent protein kinase I (CaM-kinase I) in rat retina was analyzed by immunohistochemical analysis, Western blot analysis and kinase activity assay. Western blot analysis revealed two immunoreactive bands similar to those detected in the brain. Developmental studies revealed that CaM-kinase I expression increased in accordance with postnatal development. Expression of CaM-kinase I in the retinas of rats raised in the complete darkness markedly decreased. CaM-kinase I activity assay supported these findings. Synapsin I was shown to be a possible intrinsic substrate of CaM-kinase I in rat retina. These results elucidated that CaM-kinase I is expressed in the retina and may play an important role in the retinal functions and that the expression of CaM-kinase I is regulated by light stimulation.  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