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   11414篇
  免费   791篇
  国内免费   76篇
耳鼻咽喉   191篇
儿科学   297篇
妇产科学   270篇
基础医学   1512篇
口腔科学   220篇
临床医学   784篇
内科学   2985篇
皮肤病学   292篇
神经病学   877篇
特种医学   403篇
外科学   1658篇
综合类   199篇
一般理论   2篇
预防医学   928篇
眼科学   161篇
药学   646篇
中国医学   113篇
肿瘤学   743篇
  2023年   65篇
  2022年   156篇
  2021年   314篇
  2020年   157篇
  2019年   298篇
  2018年   350篇
  2017年   250篇
  2016年   286篇
  2015年   301篇
  2014年   403篇
  2013年   528篇
  2012年   698篇
  2011年   761篇
  2010年   472篇
  2009年   473篇
  2008年   644篇
  2007年   681篇
  2006年   663篇
  2005年   632篇
  2004年   550篇
  2003年   595篇
  2002年   510篇
  2001年   302篇
  2000年   339篇
  1999年   302篇
  1998年   103篇
  1997年   95篇
  1996年   76篇
  1995年   56篇
  1994年   41篇
  1993年   56篇
  1992年   133篇
  1991年   109篇
  1990年   111篇
  1989年   87篇
  1988年   65篇
  1987年   62篇
  1986年   68篇
  1985年   61篇
  1984年   45篇
  1983年   26篇
  1982年   21篇
  1981年   14篇
  1980年   14篇
  1979年   22篇
  1978年   25篇
  1977年   14篇
  1976年   14篇
  1973年   13篇
  1971年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Having in mind the significant decrease of urinary kallikrein in rat with renal hypertension and in humans with essential hypertension, the effects of furosemide on kininogenase activity has been studied in urine of normal and hypertensive rats which received tap water or a 1% NaCl solution for drinking. Administration of 20 mg furosemide which produces maximal diuretic effect in normal rats, induced in these animals a 150–200% increase of the excretion of this enzyme after 8 hours, when compared to the activity measured before giving the drug. This increase which is observed in the normal rats drinking either water or a 1% NaCl solution shows a significant correlation with the excretion of sodium, potassium and water. In hypertensive rats, in 7 or 9 cases, an increase of kallikrein excretion (200–600%) is observed, which does not reach the levels of excretion in normal untreated rats. Furosemide did not produce increase of urinary kallikrein in hypertensive rats drinking 1% NaCl solution.  相似文献   
32.
A direct extraction of the antigens of group A beta-hemolytic streptococci from 557 throat swabs was performed by a new microtechnique of the nitrous acid extraction method with the Culturette Brand Ten-Minute Strep ID technique from Marion Scientific, Division of Marion Laboratories, Inc., Kansas City, Mo. This group A latex reagent kit contains the reagents for the micronitrous acid extraction of throat swabs and does not require a centrifugation step in its protocol. There was a 99.3% (553 of 557) total agreement between the direct nitrous acid extraction-latex agglutination method and the standard culture method. The direct extraction method yielded an identification of 95.1% (78 of 82) of the group A streptococci identified by the standard method. Throat swabs used for standard culture may also be extracted with nitrous acid for the detection of group A antigen. A 5-min nitrous acid extraction destroys the viability of bacteria associated with normal throat flora as well as group A streptococci and Mycobacterium tuberculosis. This highly rapid method is simple to perform and requires no costly instrumentation. Accordingly, it would be most applicable in a hospital laboratory as well as in a physician's office.  相似文献   
33.
34.
We report a case of ruptured mycotic aneurysm involving innominate artery requiring an urgent surgical treatment. A 62-yr-old woman presented with fever and dyspnea. Previously, she was diagnosed with colon cancer and received right hemicolectomy and one cycle of adjuvant chemotherapy. On echocardiogram, pericardial effusion was noted and emergency pericardiocentesis was performed. CT scan revealed aortic aneurysm involving ascending aorta and innominate artery, and thrombi surrounding those structures. Patch repair of the defect in the ascending aorta and ringed Goretex graft to bypass the innominate and ascending aorta were performed. We believe that this is the first case of ruptured mycotic aneurysm involving innominate artery.  相似文献   
35.
36.
Tumor metastases are extremely rare in striated muscles. This is surprising given the fact that this tissue constitutes 60% of body weight. The present study focuses on small molecules produced and secreted by muscle cells which possess anti-cancer activity in vivo. Recently we have shown that a low molecular weight fraction (<1000 Dalton) of skeletal muscle cell conditioned medium (muscle factor-MF), markedly inhibits the proliferation of carcinoma, sarcoma or melanoma cell lines in vitro. The MF exerts a cytostatic effect on tumor cell growth and arrests the cells in the G0/G1 of the cell cycle. However, normal cell proliferation, such as bone marrow and fibroblasts, was stimulated following incubation with MF. In this study, the effect of orally administered MF on melanoma and sarcoma growth was examined in mice. The administration of MF to mice inoculated intravenously with melanoma (B16–F10) or sarcoma (MCA-105) cells, resulted in a statistically significant inhibition of metastatic lung foci. In a different model, melanoma was induced in the foot pad and after development of a local lesion, the leg was amputated. A prolonged survival time was observed in the MF treated groups. Since the MF stimulated bone marrow cell proliferation in vitro, we decided to test its efficacy as an inhibitor of the myelotoxic effect exerted by chemotherapy, in vivo. MF, administered after chemotherapy, restored the number of white blood cells and yielded an increased percentage of neutrophils compared with the decline in these parameters after administration of chemotherapy alone. Thus, it is indicated that MF exerted a systemic anti tumor and chemoprotective effect when given orally. It can be concluded that it is bioavailable and is not biodegradable in the digestive system. MF may be considered as a potential therapy for the prevention of tumor spread. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
37.
38.
In chronically HIV infected individuals, a number of functional B cell abnormalities have been described. However, the immediate changes that occur in the B cell compartment following viral exposure and how they affect the long-term course of infection are not well understood. We report the longitudinal analysis of B cell repertoires during early infection in untreated and treated individuals receiving highly active antiretroviral therapy (HAART). Analysis was based on IgG heavy chain gene utilization and CDR3 length measurement and relationship with CD4/CD8 counts, viral load, and total serum IgG, and anti-HIV antibodies levels. Repertoires were assessed at baseline and at weeks 2, 4, 12, 24, and 72 after initiation of therapy. The findings indicate a stable peripheral B cell repertoire during the first 72 weeks following infection, particularly in the HAART treated patients. A modest association between B cell repertoire integrity and viremia levels as well as treatment was detected.  相似文献   
39.
The purpose of this study was to evaluate the clinical usefulness of a commercial ligase-based gene amplification method (LCxMycobacterium tuberculosis test; Abbott Laboratories, USA) for detection ofMycobacterium tuberculosis. The tuberculosis infection rate among clinical samples was 10.6%. The sensitivity, specificity, and positive and negative predictive values were 23.5%, 100%, 100%, and 91.7%, respectively, with the fluorochrome auramine stain; 32.4%, 100%, 100%, and 92.6%, respectively, with culture; and 76.5%, 95.8%, 68.4% and 97.2%, respectively, with the gene amplification method. When only samples from patients without current or previous treatment were studied, the sensitivity was 36.4% with the auramine stain, 63.6% with culture, and 100% with the gene amplification assay. The mean treatment time for culture-negative and assay-negative samples was greater than that of culture-negative and assay-positive samples. The LCxMycobacterium tuberculosis test is a sensitive method for detection and identification ofMycobacterium tuberculosis. It produces few false-positive results. However, as it can remain positive after the culture becomes negative, it is not recommended for evaluation of treatment efficiency.  相似文献   
40.
Studies on seasonal anopheline fauna variation were performed in two distinct settlements in the State of Rond?nia, Brazil: one at the Madeira River banks (Portuchuelo) with stable native Amazonian population; the other at an inland lumber-extracting farm (Urupá) in dry land, in which adults are mostly migrants. During a 6-yr period (1994-2000), 8,638 adult anophelines were collected: 2,684 in Urupá and 5,954 in Portuchuelo. Anopheles darlingi represented >95% of total mosquitoes caught. Dissection of 4,424 A. darlingi females yielded a very low sporozoite infection index below 0.1%. Oocysts were found in both localities in approximately 0.1% of dissected mosquitoes. Determination of the hour biting rates disclosed seasonal variations in both localities. However, in Portuchuelo, mosquito density peaked at the acme of the rainy season, whereas at Urupá it peaked in the dry season. The increase in mosquito density and incidence of malaria cases were coincident. The high mosquito densities observed in the riverine settlement of Portochuelo sector B, which permits evaluation in > 10,000 mosquitoes' bites/person/year, could explain, in spite of the low mosquito's infection index, the previously described development of natural immunity in the local population that is not observed in the dry land agroindustrial settlement of Urupá.  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