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   858篇
  免费   50篇
  国内免费   9篇
耳鼻咽喉   6篇
儿科学   40篇
妇产科学   5篇
基础医学   96篇
口腔科学   45篇
临床医学   74篇
内科学   176篇
皮肤病学   40篇
神经病学   28篇
特种医学   149篇
外国民族医学   1篇
外科学   83篇
综合类   39篇
预防医学   55篇
眼科学   5篇
药学   47篇
中国医学   1篇
肿瘤学   27篇
  2022年   2篇
  2021年   2篇
  2020年   4篇
  2019年   7篇
  2018年   9篇
  2017年   13篇
  2016年   14篇
  2015年   25篇
  2014年   15篇
  2013年   28篇
  2012年   21篇
  2011年   27篇
  2010年   31篇
  2009年   46篇
  2008年   23篇
  2007年   30篇
  2006年   15篇
  2005年   16篇
  2004年   30篇
  2003年   16篇
  2002年   8篇
  2001年   6篇
  2000年   7篇
  1999年   18篇
  1998年   54篇
  1997年   62篇
  1996年   56篇
  1995年   42篇
  1994年   40篇
  1993年   37篇
  1992年   9篇
  1991年   14篇
  1990年   16篇
  1989年   14篇
  1988年   24篇
  1987年   23篇
  1986年   22篇
  1985年   9篇
  1984年   4篇
  1983年   8篇
  1982年   18篇
  1981年   3篇
  1980年   9篇
  1979年   4篇
  1978年   4篇
  1977年   5篇
  1976年   6篇
  1975年   3篇
  1968年   3篇
  1959年   2篇
排序方式: 共有917条查询结果,搜索用时 0 毫秒
51.

Objective

To identify the vector(s), the parasite and the species composition of sand flies in the district during May-October 2012.

Methods

For reaching our objectives we used polymerase chain reaction of kDNA, ITS1-rDNA, followed by restriction fragment length polymorphism.

Results

Two species of Phlebotomus sergenti and Phlebotomus tobbi were the most prevalent among 8 species identified comprising 51.1% and 32.9% respectively. Among the 160 specimens of female sand flies tested by polymerase chain reaction of kDNA, ITS1-rDNA, followed by restriction fragment length polymorphisms, only 1 out of 80 Phlebotomus tobbi (1.25%) were positive to Leishmania infantum parasites.

Conclusions

Our finding showed that Phlebotomus tobbi may play as a vector to circulate the parasite of Leishmania infantum among reservoir(s) and human.  相似文献   
52.
Southeast Asian ovalocytosis (SAO) is an asymptomatic trait characterized by rigid, poorly deformable red cells that resist invasion by several strains of malaria parasites. The underlying molecular genetic defect involves simple heterozygous state for a mutant band 3 protein, which contains a deletion of amino acids 400 through 408, linked with a Lys 56-to-Glu substitution (band 3-Memphis polymorphism). To elucidate the contribution of the mutant SAO band 3 protein to increased SAO red blood cell (RBC) rigidity, we examined the participation of the mutant SAO band 3 protein in increased band 3 attachment to the skeleton and band 3 oligomerization. We found first that SAO RBC skeletons retained more band 3 than normal cells and that this increased retention preferentially involved the mutant SAO band 3 protein. Second, SAO RBCs contained a higher percentage of band 3 oligomer-ankyrin complexes than normal cells, and these oligomers were preferentially enriched by the mutant SAO protein. At the ultrastructural level, the increased oligomer formation of SAO RBCs was reflected by stacking of band 3-containing intramembrane particles (IMP) into longitudinal strands. The IMP stacking was not reversed by treating SAO RBCs in alkaline pH (pH 11), which is known to weaken ankyrin-band 3 interactions, or by removing the cytoplasmic domain of band 3 from SAO membranes with trypsin. Finally, we found that band 3 protein in intact SAO RBCs exhibited a markedly decreased rotational mobility, presumably reflecting the increased oligomerization and the membrane skeletal association of the SAO band 3 protein. We propose that the mutant SAO band 3 has an increased propensity to form oligomers, which appear as longitudinal strands of IMP and exhibit increased association with membrane skeleton. This band 3 oligomerization underlies the increase in membrane rigidity by precluding membrane skeletal extension, which is necessary for membrane deformation.  相似文献   
53.
54.
Between June 1989 and June 1992, 144 patients participated in sequential clinical trials using peripheral blood progenitor cells (PBC) as their sole source of hematopoietic rescue following high-dose chemotherapy. All patients had received prior extensive combination chemotherapy and had marrow defects that precluded autologous bone marrow transplantation (ABMT). PBC were collected according to a single apheresis protocol. The initial 86 patients (group 1) had PBC collected without mobilization. Beginning in April 1991, PBC were mobilized solely with recombinant human granulocyte-macrophage colony-stimulating factor (rHuGM-CSF). Thirty-four patients (group 2) received rHuGM-CSF at a dose of 125 micrograms/m2/d by continuous intravenous infusion, and 24 patients (group 3) received rHuGM-CSF at a dose of 250 micrograms/m2/d by continuous intravenous infusion. Patients underwent at least six aphereses and had a minimum of 6.5 x 10(8) mononuclear cells (MNC)/kg collected. Cytokines were not routinely administered immediately after transplantation. A median of nine aphereses were required to collect PBC in group 1 and seven aphereses for groups 2 and 3 (P = .03). The time required to recover 0.5 x 10(9)/L granulocytes after transplant was significantly shorter (P = .0004) for the mobilized groups; the median time to recovery was 26 days for group 1, 23 days for group 2, and 18 days for group 3. Transplantation of PBC mobilized with rHuGM-CSF resulted in a shorter time to platelet (P = .04) and red blood cell (P = .01) transfusion independence. Mobilization with rHuGM-CSF alone resulted in efficient collection of PBC, that provided rapid and sustained restoration of hematopoietic function following high-dose chemotherapy. Mobilization of PBC with rHuGM-CSF alone is an effective method for patients who have received prior chemotherapy and have bone marrow abnormalities.  相似文献   
55.
Between February, 1985, and August, 1987, 76 patients with mitral stenosis underwent percutaneous transarterial mitral balloon valvuloplasty (MVP). There were 58 females and 18 males aged from 15 to 69 years (mean 39 +/- 11). In 31 patients the mitral valve was pliable (40%) and in 45 patients (60%) the valve was nonpliable. Calcified mitral stenosis was found in 24 patients (31%). Transseptal catheterization was used to place one or two 0.035" (350 cm long) exchange wires into the ascending aorta in order to be snared, retrieved and exteriorized, each one through a femoral artery. Over these wires, the balloon dilation catheters were advanced through the femoral artery, retrogradely, across the mitral valve, for mitral dilation. Single (25 mm in diameter, trefoil 3 x 12 mm, bifoil 2 x 19 mm) and double (18 and 15 mm, 18 and 18 mm, 18 and 20 mm) balloons were used in 24 and 52 patients respectively. Transarterial mitral valvuloplasty produced immediate improvement of mitral valve area (MVA = 1.1 +/- 0.3 to 2.4 +/- 0.4 cm2, p less than 0.001), mitral valve gradient (19 +/- 4 to 8 +/- 6 mmHg, p less than 0.001), echocardiographic left atrial diameter (LAD = 58 +/- 6 to 54 +/- 5 mm, p greater than 0.05) and echo-MVA (0.9 +/- 0.4 to 2.1 +/- 0.7, p less than 0.001). In three patients no MVA enlargement was achieved. A significant mitral regurgitation was produced in two patients. A stroke occurred in three patients (3.9%), one of these patients subsequently died (1.3%), one recovered and one remained hemiplegic. No atrial septal defect was found after valvuloplasty.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
56.
57.
Permanent impairment of embryo development by hydrosalpinges   总被引:6,自引:9,他引:6  
Recent reports suggest a deleterious effect of hydrosalpinges on pregnancy outcome for in-vitro fertilization (IVF) and improvement following surgical treatment. We compared the effect of hydrosalpinx on pregnancy outcome in 286 patients having 348 IVF cycles and followed the development of untransferred embryos for 7 days to determine if hydrosalpinges affect oocyte quality or embryo development. The delivery rate per retrieval was significantly lower for patients with hydrosalpinx, but was restored by surgical treatment to that of patients without hydrosalpinx. However, the implantation rate per embryo transferred and normal blastulation of untransferred embryos, which were significantly decreased in patients with hydrosalpinx, and growth arrest and degeneration of untransferred embryos, which were significantly increased compared to patients without hydrosalpinx, were not restored by surgical treatment of hydrosalpinges. We conclude that surgical treatment of hydrosalpinges decreases early pregnancy loss and improves pregnancy outcome, possibly by diminishing reversible deleterious effects exerted on the endometrium. As we have seen in our laboratory, hydrosalpinges may have a permanent negative influence on ovarian function, follicular development and oocyte quality since implantation of transferred embryos and normal blastulation of untransferred embryos remain low, and in-vitro growth arrest and degeneration remain high despite surgical treatment of hydrosalpinges.   相似文献   
58.
AIMS: Long acting subcutaneous testosterone pellets are of proved efficacy for the treatment of hypogonadal men, but have not been reported as a treatment modality in adolescent boys. Pharmacodynamic studies of subcutaneous testosterone release have shown prolonged normalisation of testosterone levels for at least four months. Administration of a long acting, safe, effective, and convenient form of treatment is desirable when life-long treatment is indicated. PATIENTS AND METHODS: Eighteen boys (aged 13.9-17.5 years at the start of treatment)-seven with primary hypogonadism, nine with secondary hypogonadism, and two boys being treated with testosterone for tall stature--were given testosterone pellets (8-10 mg/kg) every six months for 18 months. Height, weight, pubertal status, and psychosocial parameters were assessed and follicle stimulating hormone, luteinising hormone, testosterone, prolactin, and lipids were measured at 0, 1, 3, 6, 12, and 18 months. Bone age was measured at 0 and 12 months. RESULTS: In all boys growth velocity continued appropriately for bone age. Puberty continued to progress in all boys and in two boys the amount of virilisation exceeded that seen with previous treatment with intramuscular testosterone. After testosterone administration, follicle stimulating hormone and luteinising hormone suppressed incompletely in the boys with primary hypogonadism. Serum testosterone ranged from 4.3 to 26.7 nmol/l at three months to less than 10 nmol/l at six months after implantation. Prolactin and lipid levels were normal throughout the study. By report, there was an improvement in mood and emotional wellbeing. No pellet extrusions occurred in a total of 156 pellet insertions. CONCLUSIONS: All boys preferred this mode of testosterone administration to intramuscular injections. Long acting subcutaneous testosterone pellets are safe, efficacious, well tolerated, and convenient, and result in normal physical growth and improved psychological outlook in adolescent hypogonadal boys.  相似文献   
59.
郑运松  徐会吾 《医学争鸣》2009,(21):2435-2437
目的:探讨Balo病同心圆硬化(BCS)的磁共振表现特征及其病理基础.方法:回顾性分析4例Balo病同心圆硬化患者的MRI表现,均经激素治疗临床症状好转后行MRI复查.结果:4例患者中,1例单发,3例多发,最多者病灶5个.病变主要累及大脑半球皮层下和深部白质区,共发现11个病灶,其中顶叶半卵圆中心和颞叶的发病比例高.典型同心圆样病灶8个,直径1~2.3cm,同心圆层数为3~5个.在T1WI加权像呈等、低信号相间;T2WI,FLAIR像上呈等、高信号交替环,病灶周围有轻度水肿表现,上述表现与镜下脱髓鞘区与髓鞘保留区相间相对应.其余3个不典型的病灶呈斑片状或煎蛋样改变;增强后1例病灶呈点状或边缘线状强化.结论:Balo病同心圆性硬化的MRI及其增强扫描具有特征性表现,可作为本病诊断的主要方法,并可用于疗效的观察.  相似文献   
60.
The effect of barium on blood in the gastrointestinal tract   总被引:2,自引:0,他引:2  
  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