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   10519篇
  免费   1068篇
  国内免费   595篇
耳鼻咽喉   134篇
儿科学   106篇
妇产科学   91篇
基础医学   1379篇
口腔科学   148篇
临床医学   1349篇
内科学   1876篇
皮肤病学   88篇
神经病学   565篇
特种医学   342篇
外国民族医学   15篇
外科学   1096篇
综合类   1400篇
现状与发展   6篇
一般理论   1篇
预防医学   663篇
眼科学   107篇
药学   1071篇
  35篇
中国医学   712篇
肿瘤学   998篇
  2024年   27篇
  2023年   178篇
  2022年   464篇
  2021年   746篇
  2020年   560篇
  2019年   501篇
  2018年   490篇
  2017年   446篇
  2016年   466篇
  2015年   706篇
  2014年   811篇
  2013年   774篇
  2012年   971篇
  2011年   979篇
  2010年   685篇
  2009年   532篇
  2008年   522篇
  2007年   533篇
  2006年   456篇
  2005年   452篇
  2004年   148篇
  2003年   151篇
  2002年   134篇
  2001年   76篇
  2000年   60篇
  1999年   50篇
  1998年   30篇
  1997年   28篇
  1996年   16篇
  1995年   22篇
  1994年   25篇
  1993年   15篇
  1992年   23篇
  1991年   10篇
  1990年   14篇
  1989年   9篇
  1988年   11篇
  1987年   9篇
  1986年   4篇
  1984年   3篇
  1983年   5篇
  1978年   2篇
  1977年   3篇
  1976年   5篇
  1973年   3篇
  1970年   3篇
  1968年   4篇
  1965年   2篇
  1962年   2篇
  1926年   2篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
21.
Urethral reconstruction with graft substances, such as skin and bladder mucosa, has been previously used when primary anastomosis cannot be achieved. However, stricture and meatal prolapse are associated with these grafts. We report the use of buccal mucosa for the reconstruction of urethral defects in 3 patients. One patient with failed operation for hypospadias received tube buccal mucosal graft for urethral replacement. Two patients with urethral necrosis and stricture received onlay buccal mucosal graft. All patients were disease-free during follow-up (range, 12 to 49 months; mean, 36 months). One patient had a pinhole fistula that was successfully managed with simple repair. This technique appears to be useful for urethral reconstruction when a local graft is not available, even in patients with complicated conditions.  相似文献   
22.
OBJECTIVE: To investigate the characteristics of Hep-2 cell with multidrug resistance (MDR) induced by Taxol. STUDY DESIGN: Hep-2 cells were exposed in stepwise escalating concentration of Taxol to develop the resistant cell line-Hep-2T. Cell cycle distribution, apoptosis, and rhodamine accumulation were studied through flow cytometry. The MDR1 and MRP1 genes were detected through real-time quantitative RT-PCR, and the corresponding proteins were detected through Western blotting. RESULTS: The drug resistance of Hep-2T cells to Taxol, doxorubicin, gemcitabine, 5-FU, and cisplatin all increased. The percentage of G0/G1 phase and the antiapoptosis ability increased significantly compared with Hep-2 cells. Both MDR1 and MRP1 also increased at gene and protein level, though MDR1 was more prominent. CONCLUSION: More emphasis should be laid on MDR1/Pgp, the non-Pgp substrate chemotherapeutic agents, and the changes of cell cycle distribution to prevent MDR induced by Taxol. SIGNIFICANCE: These findings may provide theoretical support for the reverse of MDR.  相似文献   
23.
We have developed a sensitive enzymatic-immunoassay to quantify the level of gamma-enolase (a specific neuronal enzyme) which is released from cultured cells after exposure to various toxins. We show that this method can estimate selectively neuronal cell death without significantly interfering with glial cell death. Indeed, no gamma-enolase is released when glial cells are killed with free-radical producing agents. Experiments comparing the levels of neuronal cell death induced by NMDA or free-radical producing drugs, performed either by measuring gamma-enolase release or using the classical fluorescein diacetate method, yielded similar results. In addition to selectively follow neuronal death in a mixed population of neurons and glial cells, this method provides a way of determining the cell death kinetics from a single culture dish, since enolase can be measured on small samples taken from the culture medium. Finally, we propose these two methods as being complementary and useful neuronal and other cellular death indexes and also to understand the complex problem of glial influence on neuronal survival or death.  相似文献   
24.
永瓣藤化学成分的研究   总被引:2,自引:1,他引:1  
永瓣藤化学成分的研究陈玲,谢平,戚薇,曾菊珍(药学系中药化学教研室)关键词永瓣藤,化学成分,三萜,蒜盘子甾酮永瓣藤(MonimopetalnmChinenseRe-hd)系卫矛科永瓣藤属植物[1],为我国特有的珍稀二类保护植物[2],分布于江西东北部...  相似文献   
25.
目的构建在视网膜组织特异性表达的人血管内皮生长因子(VEGF)165基因。方法用聚合酶链反应(PCR)方法从BLAB/C鼠全基因组扩增能在视网膜组织特异性表达的rho启动子,经限制性内切酶纯化后克隆于质粒pcDNA3.1+-VEGF165中,建立重组质粒pcDNA3.1+-rho-VEGF165,通过限制性内切酶酶切分析及PCR鉴定筛选出正确重组质粒pcDNA3.1+-rho-VEGF165,由jetPEI介导转染人视网膜色素上皮细胞和人脐静脉内皮细胞,并通过免疫组织化学染色以及绘制细胞生长曲线检测在人视网膜色素上皮细胞和人脐静脉内皮细胞中VEGF蛋白的表达。结果在人视网膜色素上皮细胞中,重组质粒pcDNA3.1+-rho-VEGF165比质粒pcDNA3.1+-rho-VEGF165的VEGF蛋白表达强,在人脐静脉内皮细胞,两者的表达量无明显差别。结论pcDNA3.1+-rho-VEGF165载体的构建为进一步研究VEGF在视网膜新生血管形成中的致病机理提供基础材料,并为进一步建立视网膜特异性表达VEGF转基因鼠模型建立了基础。(中华眼底病杂志,2005,21:106-109)  相似文献   
26.
Management of chronic lunotriquetral ligament tears   总被引:1,自引:0,他引:1  
Treatment of chronic disruptions of the lunotriquetral (LT) ligament is not well-defined. Eleven patients treated by LT fusion with use of a compression screw are reported. The injury frequently resulted from hyperextension of the wrist. Pain on the ulnar side of the wrist, limited motion, and tenderness over the LT joint exacerbated by ballottement were present. Standard radiographs were normal. Arthrography showed the ligamentous tear in all cases. After operation, immobilization was continued until fusion was apparent radiographically. Fusion was achieved in all cases between 2 and 5 months. Four patients were free of pain, four patients had pain only at the extremes of motion, and three patients had persistent pain. Mean wrist motion was as follows (preoperative/postoperative): flexion (53 degrees/45 degrees), extension (60 degrees/49 degrees), radial deviation (17 degrees/21 degrees), and ulnar deviation (25 degrees/18 degrees). Maximum grip strength as a percentage of the uninjured side was 73% preoperatively and 59% postoperatively. LT tears can exist de novo or as part of the ulnar impaction syndrome; a method for differentiation is presented.  相似文献   
27.
Levels of the c-fos protein were assayed in mouse cerebellar granule cells during their in vitro development under different culture conditions. When grown in media favoring both their survival and differentiation, i.e. in the presence of 30 mM K+ or 12.5 mM K+ plus 100 microM N-methyl-D-aspartate (NMDA), the c-fos protein becomes detectable in the nucleus of granule cells on and after 6 days and persists to high levels until the culture begins to decline. The protein c-fos appears therefore after the critical period described for the survival effect of K+ depolarization or NMDA receptor stimulation which corresponds to days 2-5 after plating. The c-fos protein remains however scarcely detectable or undetectable throughout the life-span of cells cultured under conditions providing poor survival and differentiation, i.e. in the presence of low K+ (5 or 12.5 mM) alone or when the effect of NMDA is blocked by the NMDA receptor antagonist MK-801. Interestingly, in cortical and striatal neurons, the survival and differentiation of which being not affected by depolarizing media, no c-fos protein is detected whatever the culture conditions tested at least during the first 18 days in vitro. This suggests that long-term expression of the c-fos gene might be related to some aspect of the late in vitro differentiation process of cerebellar granule cells.  相似文献   
28.
脉动真空灭菌器内室气体流向监测报警装置的研制   总被引:2,自引:2,他引:0  
本文针对XGI型脉动真空灭菌柜出现的蒸汽倒流故障设计出一种内室气体流向监测报警装置,对管道中的蒸汽流向和空气流向进行监测。当出现倒流现象时,报警装置发出报警信号,提醒工作人员采取措施排除故障。经在两台灭菌柜上使用,证明此方案是一种行之有效的方法。  相似文献   
29.
For the detection of the synthesis in vitro of anti-Mycobacterium leprae antibodies in various tissues of leprosy patients, biopsy specimens of skin lesions, nasal mucosa, larynx, lymph nodes, and bone marrow were cultured in a medium containing 14C-labeled lysine and isoleucine. The culture fluids were analyzed by crossed immunoelectrophoresis with intermediate gel and autoradiography. The results show that synthesis of anti-M. leprae antibodies occurs at the investigated sites of leprosy patients and that the specificities of the synthesized antibodies differ between sites in individual patients. It is conceivable that these antibodies play a role in the local defense against M. leprae.  相似文献   
30.
目的:克隆菠菜乙醇酸氧化酶cDNA并构建其酵母表达载体。方法:从新鲜菠菜叶子中提取总RNA,用RT-PCR法扩增菠菜乙醇酸氧化酶编码区cDNA并插入pMD-T载体中进行序列测定;将此cDNA构建入P.Pastoris酵母表达体系中的pPIC3.5k上的SnaBI/NotI位点,进行PCR筛选和限制性酶切鉴定。结果:测序表明获得的基因为乙醇酸氧化酶cDNA序列,与国外文献报道的序列相比有约98%的同源性;重组质粒的SnaBI/NotI双酶切证明构建正确。结论:菠菜乙醇酸氧化酶cDNA克隆及重组质粒pPIC3.5K-GO的获得,为酵母表达菠菜乙醇酸氧化酶提供了前题条件。  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