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   1885篇
  免费   75篇
  国内免费   17篇
耳鼻咽喉   14篇
儿科学   15篇
妇产科学   4篇
基础医学   201篇
口腔科学   63篇
临床医学   96篇
内科学   543篇
皮肤病学   18篇
神经病学   123篇
特种医学   49篇
外科学   358篇
综合类   6篇
预防医学   25篇
眼科学   15篇
药学   112篇
中国医学   1篇
肿瘤学   334篇
  2023年   8篇
  2022年   20篇
  2021年   35篇
  2020年   21篇
  2019年   28篇
  2018年   30篇
  2017年   33篇
  2016年   35篇
  2015年   36篇
  2014年   45篇
  2013年   68篇
  2012年   76篇
  2011年   128篇
  2010年   72篇
  2009年   52篇
  2008年   87篇
  2007年   97篇
  2006年   117篇
  2005年   97篇
  2004年   103篇
  2003年   110篇
  2002年   113篇
  2001年   72篇
  2000年   60篇
  1999年   58篇
  1998年   27篇
  1997年   20篇
  1996年   16篇
  1995年   26篇
  1994年   23篇
  1993年   22篇
  1992年   27篇
  1991年   33篇
  1990年   24篇
  1989年   25篇
  1988年   17篇
  1987年   10篇
  1986年   12篇
  1985年   8篇
  1984年   6篇
  1983年   10篇
  1982年   8篇
  1981年   5篇
  1979年   5篇
  1978年   6篇
  1977年   5篇
  1974年   9篇
  1973年   4篇
  1971年   7篇
  1969年   5篇
排序方式: 共有1977条查询结果,搜索用时 187 毫秒
21.
22.
23.
A 46-year-old man with chronic myelogenous leukemia was found to have a new complex translocation. In chronic phase, all of the bone marrow cells had a rearrangement of a t(2;9;14;22) (p21;q34;q32;q11). Southern blot analysis of leukocyte DNA revealed rearrangement of the breakpoint cluster region (bcr) within the 5.8-Kb bcr. The patient eventually died in blast crisis 28 months later. The cytogenetic findings of bone marrow cells showed a 46,XY,t(2;9;14;22)(p21;q34;q32;qll),add(lp),del(3q) karyotype in blast crisis.  相似文献   
24.
In order to why polymorphonuclear leukocytes (PMNs) are predominant and mononuclear leukocytes (MNLs) are few in rheumatoid synovial fluids, chemotactic factor(s) for PMNs and MNLs were studied in the synovial fluids of rheumatoid arthritis (RA-SF) and osteoarthritis (OA-SF) using both Boyden's and agarose methods. The RA-SF showed strong chemotactic activity for human peripheral blood PMNs compared with non-rheumatoid OA-SF. The chemotactic activity for PMNs was well correlated with the number of PMNs in RA-SF, suggesting that it was a natural mediator for PMN emigration into rheumatoid joint cavity. The major chemotactic factor for PMN in RA-SF was of apparent molecular weight of 14,000 and its activity was suppressed to less than 10 percent by anti-C5a antibody, but it failed to show any anaphylatoxin activity which was an attribute of C5a. It was, therefore, suggested to be C5a-like molecule but not C5a itself. The possibility that the factor may be a C5a des-Arg was discussed. On the contrary, the chemotactic activity for MNLs was not found neither in RA-SF nor OA-SF. These findings may explain the fact that PMNs are predominant in rheumatoid synovial fluids.  相似文献   
25.
The incidence and transplantability of ovarian teratoma in LT/Sv mice were examined following cisplatin treatment at the age of 16 days, and compared to those in the control group. Cisplatin had not affected the emergence of egg cleavage, which simultaneously appeared in the mouse ovaries in both groups. Although 7 teratomas, occasionally transplantable, developed in the control mice aged over 30 days, only 2 tumors occurred in cisplatin-treated mice at the age of 120 days and they were not transplantable. The results suggest that cisplatin might influence the tumorigenic process after egg cleavage, or transplantability of teratoma.  相似文献   
26.
OBJECTIVE: Our objective was to determine the changes in regional ventricular wall motion during minimally invasive direct coronary artery bypass grafting by color kinesis using transesophageal echocardiography. METHODS: Minimally invasive coronary artery bypass grafting was performed in 34 patients, during which transesophageal echocardiography was used. Thirteen patients had isolated disease of the left anterior descending artery. Regional ventricular wall motion was analyzed by color kinesis with the SONOS 2500 transesophageal echocardiograph (Hewlett-Packard Co, Andover, Mass). On-line assessment of regional wall motion was continued during the operation. RESULTS: Wall motion abnormalities during ischemia were present in 4 cases, left ventricular mid-anterior hypokinesis in 3 cases, and left ventricular apical-lateral hypokinesis in 1 case. In all cases, wall motion was maintained after bypass. In patients with total coronary occlusion, changes in wall motion did not occur during anastomosis. CONCLUSIONS: Color kinesis allowed us to evaluate the change in regional ventricular wall motion induced by myocardial ischemia during minimally invasive coronary artery bypass grafting both objectively and quantitatively.  相似文献   
27.
To determine whether bucolome (5-n-butyl-1-cyclohexyl-2,4,6-trioxoperhydropyrimidine), a nonsteroidal anti-inflammatory agent, can reverse diuretic resistance of furosemide in patients with nephrotic syndrome, we examined the inhibitory effect of bucolome on the protein binding of furosemide in serum and urine. Bucolome significantly inhibited the protein binding of furosemide not only in serum but also in urine of preparation albumin (UPA), which mimics urinary albumin concentration in patients with nephrotic syndrome by ultrafiltration method. The binding percentage of furosemide to albumin was approximately 70% in UPA. With coadministration of bucolome to healthy volunteers, renal clearance of furosemide was increased, reflecting the increase of the free fraction of furosemide in serum. Furthermore, coadministration of bucolome caused a significant increase of urine volume and sodium concentration in urine. Even at higher urine levels of furosemide, the inhibitory effect of bucolome on the protein binding of furosemide in UPA remains constant, and changes in pH at weakly acidic pH levels (pH 5.5-6.5) did not alter the inhibitory effect of bucolome. Interestingly, coadministration of bucolome with furosemide in doxorubicin (Adriamycin)-induced nephrotic syndrome model rats alleviated the diuretic resistance. These results suggest that bucolome has a potent inhibitory effect on the protein binding of furosemide in the urine and can partially restore the diuretic response of furosemide in patients with nephrotic syndrome by increasing the free fraction of furosemide at the site of action.  相似文献   
28.
In this study, the degradates generated from a pharmaceutical solid were characterized, and a mechanistic pathway underlying their formation was proposed. The chemical stability of a novel triazole antifungal drug, CS‐758, deteriorated significantly when the crystal was disordered, and characteristic degradates were generated. A total of eight degradates in solution and nine degradates in a solid state were isolated by preparative liquid chromatography. Degradates were characterized using high‐performance liquid chromatography–photodiode array, mass spectrometry, and nuclear magnetic resonance. Radical‐mediated oxidation is proposed as the main degradation pathway in the solid state. The initiation step of this pathway is hydrogen atom abstraction from a methine carbon that is adjacent to a dien moiety and the formation of a delocalized vinylic radical intermediate. Molecular oxygen is then added to the radical position to form hydroperoxides. There are three potential oxidation routes based on the proposed autoxidation pathway that lead to the generation of the dioxane ring‐opening hydroxyl form, the 9,10‐epoxide form, or the 11,12‐epoxide form, depending on the substituted position of the added molecular oxygen. The epimer compound generated via the vinylic radical intermediate and sulfoxides was characterized. This degradation mechanism provides the scientific foundation for an oxidative stressing system currently under investigation.  相似文献   
29.
Two cases where aberrant tissue was attached to the lower lip mimicking the inferior labial frenum were reported. The frenum-like tissue extended from the gingival margin between the lower left deciduous central and lateral incisors in case 1 and between the lower right deciduous central and lateral incisors in case 2, to the dry lower lip. Histologically, the resected specimen was regarded as normal oral mucosa covered with stratified squamous epithelium, without a clear amniotic band. The frenum-like tissue of the lower lip found in both our patients was diagnosed as a category of oral synechiae, of unknown origin.  相似文献   
30.
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