全文获取类型
收费全文 | 255854篇 |
免费 | 23507篇 |
国内免费 | 15833篇 |
专业分类
耳鼻咽喉 | 2536篇 |
儿科学 | 2832篇 |
妇产科学 | 3160篇 |
基础医学 | 30859篇 |
口腔科学 | 4545篇 |
临床医学 | 31919篇 |
内科学 | 37000篇 |
皮肤病学 | 3614篇 |
神经病学 | 13179篇 |
特种医学 | 10177篇 |
外国民族医学 | 115篇 |
外科学 | 26069篇 |
综合类 | 40783篇 |
现状与发展 | 62篇 |
一般理论 | 28篇 |
预防医学 | 17262篇 |
眼科学 | 6989篇 |
药学 | 27724篇 |
255篇 | |
中国医学 | 14641篇 |
肿瘤学 | 21445篇 |
出版年
2024年 | 895篇 |
2023年 | 3817篇 |
2022年 | 9956篇 |
2021年 | 12800篇 |
2020年 | 9519篇 |
2019年 | 8309篇 |
2018年 | 8807篇 |
2017年 | 8157篇 |
2016年 | 7933篇 |
2015年 | 12079篇 |
2014年 | 14779篇 |
2013年 | 13963篇 |
2012年 | 20387篇 |
2011年 | 21931篇 |
2010年 | 14195篇 |
2009年 | 11354篇 |
2008年 | 14745篇 |
2007年 | 13929篇 |
2006年 | 13340篇 |
2005年 | 12540篇 |
2004年 | 8503篇 |
2003年 | 7987篇 |
2002年 | 6621篇 |
2001年 | 5220篇 |
2000年 | 5107篇 |
1999年 | 5013篇 |
1998年 | 3032篇 |
1997年 | 3003篇 |
1996年 | 2331篇 |
1995年 | 2245篇 |
1994年 | 2002篇 |
1993年 | 1225篇 |
1992年 | 1626篇 |
1991年 | 1431篇 |
1990年 | 1155篇 |
1989年 | 1087篇 |
1988年 | 922篇 |
1987年 | 795篇 |
1986年 | 596篇 |
1985年 | 485篇 |
1984年 | 244篇 |
1983年 | 198篇 |
1982年 | 130篇 |
1981年 | 148篇 |
1980年 | 105篇 |
1979年 | 124篇 |
1978年 | 58篇 |
1977年 | 53篇 |
1976年 | 46篇 |
1974年 | 48篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
From July 1989, to June 1996, 160 patients with congenital bile duct dilatation (CBD) were treated at our institution. The
incidence of CBD at our institution has increased annually. In approximately 90% of patients with CBD there was associated
anomalous arrangement of the pancreaticobiliary ductal system, and we concluded that this was one of the main causes of CBD.
Pediatric endoscopic retrograde cholangiopancreatography was first introduced to China in 1989, and has been successfully
performed in 90.2% of 92 patients at our institution. We found that age at diagnosis was closely related to the subtype, complications,
and mortality of CBD. The subtype also correlated with the presenting symptoms. One hundred and forty-seven of the 160 patients
underwent surgery. Of these 147 patients, 136 (92.5%) were cured with normal liver function and 9 (6.1%) improved with liver
impairment. Two patients died, one of postoperative pneumonia and one of liver failure. We conclude that early radical surgery
and careful postoperative follow-up are essential in the prevention of CBD complications such as cholangitis, pancreatitis,
biliary stones, and development of carcinoma.
This article is based on a special lecture delivered before the 19th meeting of the Japanese Society of Pancreatico-biliary
Maljunction, on September 14, 1996, in Tokyo 相似文献
92.
Summary The vestibulospinal level of vestibular function is commonly neglected in the evaluation of vertiginous patients. We have now developed a new posture equilibrometer. A transducer is placed on the head of the subject being tested. With this meter we can record body swaying, X (left-right) and Y (fore-aft) components of angular displacement, angular velocity, and angular acceleration. A detailed analysis of the data can be made by having patients keep their eyes either open or closed during the Romberg test. The head is turned left or right in this test, while the eyes are opened and closed in the Mann test. The posture equilibrometer has enabled us to evaluate more precisely vestibulospinal function and sensory interactions.
Offprint request to: N. C. Zhong 相似文献
93.
94.
Cells with natural killer activity (NK) may play an important role in host defence against tumour cells. The lytic function of NK cells is very sensitive to hyperthermic inactivation. However, cells with NK activity isolated from rat spleen and exposed to 41-42.5 degrees C for 30 min could partially recover their cytotoxic activity after incubation at 37 degrees C. The recovered cytotoxicity was still NK-specific, as it only resulted in the lysis of YAC-1 sensitive targets, and could not lyse NK-resistant P815 mastocytoma cells. Conjugate formation assay using NK cells labelled with specific monoclonal antibody (mAb) 3.2.3 indicated that the binding of NK cells to targets was not significantly affected by heat treatment. Compared to controls, however, microtubule organizing centre (MTOC) reorientation towards the region of intercellular contact was reduced by 40% in heated effector cells. This was accompanied by a greater inhibition (62-77%) of NK lytic activity. Kinetic analysis indicated that MTOC reorientation capacity recovered following incubation at 37 degrees C. MTOC recovery was maximal 4 h after treatment whereas that of lytic activity peaked at 6 h. These data indicate that NK cells recover NK-specific lytic activity after heat inactivation. Moreover, our study demonstrates that hyperthermia interferes with post-binding MTOC reorientation, and further supports a role for microtubule in secretory processes involved in NK-mediated cytolysis. 相似文献
95.
Chih-Hsin Tang Rong-Sen Yang Houng-Chi Liou Wen-Mei Fu 《Journal of bone and mineral research》2003,18(3):502-511
The skeletal extracellular matrix produced by osteoblasts contains the glycoprotein fibronectin (Fn), which regulates the adhesion, differentiation, and function of osteoblasts. Fn fibrillogenesis is involved in the process of bone mineralization. Bone morphogenetic proteins (BMPs) can be isolated from organic bone matrix and are able to initiate de novo cartilage and bone formation. In this study, the effect of BMP-4 on Fn fibrillogenesis in cultured rat osteoblasts was examined. BMP-4 enhanced Fn synthesis and extracellular Fn assembly in primary cultured osteoblasts. In addition, the extracellular assembly of Fn from exogenously applied soluble human Fn was also increased by BMP-4. It has been reported that alpha5beta1 integrin is related to Fn fibrillogenesis. The synthesis of both alpha5 and beta1 integrins was upregulated by BMP-4. Immunocytochemistry showed that the clustering of alpha5 and beta1 integrins was also increased by BMP-4. BMP-4 increased fibril formation of Fn and the adhesion of osteoblasts onto Fn matrix, which was inhibited by disintegrin triflavin and Gly-Arg-Gly-Asp-Ser (GRGDS) peptide. Phosphorylation of extracellular signal-regulated kinase (ERK) and focal adhesion kinase (FAK) was increased by BMP-4. Enhancement of extracellular Fn fibrillogenesis and the mRNA expression of beta1 integrin by BMP-4 were inhibited by ERK kinase (MEK) inhibitor PD98059. These results suggest that the enhancement of extracellular Fn fibrillogenesis by BMP-4 in cultured osteoblasts is related to the increase of the synthesis of Fn and clustering of alpha5 and beta1 integrins. ERK is involved in the signaling pathway of BMP-4 in regulating Fn fibrillogenesis in osteoblasts. 相似文献
96.
烧伤大鼠血清对血管内皮细胞通透性的影响 总被引:4,自引:2,他引:2
加深入阐明严重烧伤早期全身血管通透性增加继而引直民早期损害的发生机制,本实验应用培养于微孔滤膜上的小牛瞌 及皮细胞单层所构成的选择性通透屏障模型,观察了30%Ⅲ度烧伤大鼠血清对其影响,结果发现,烧伤早期烧伤血清刺激后EC单层对Hanks液或白蛋白液滤过流量、滤过系数均明显增加。 相似文献
97.
L Fuller J Fernandez S Zheng M Carreno V Esquenazi W C Yang J Miller 《Transplantation》1992,53(1):195-202
We have advanced the hypothesis that the primary autolymphoproliferative response of dog T cells in mixed lymphocyte kidney cultures (MLKC) results from their recognition of tissue-specific (kidney-associated) antigen(s) presented in conjunction with class II MHC antigens. Lymphocyte culture-derived supernatants had been found previously to upregulate class II antigen expression on kidney cells and enhance T cell activation. In the present study we have isolated and characterized dog IFN-gamma, a class II-inducing substance that is secreted in the culture supernatant of activated T lymphocytes. Dog IFN-gamma was induced with A-23187 and PMA and purified stepwise using controlled-pore glass, Mono Q anion exchange chromatography, and Superose 6-gel filtration on FPLC. The purification resulted in two molecules of 42 Kd and 31 Kd molecular weights. An IgG1 monoclonal antibody was engendered to these molecules. With this mAb reagent, in immunochemical experiments, we have developed a sensitive ELISA and a method for purifying dog IFN-gamma by affinity chromatography. Species specificity studies indicated that purified dog IFN-gamma reacted with a polyclonal rabbit antihuman IFN-gamma, but not with a mAb to human IFN-gamma. However, the antidog IFN-gamma mAb that was generated also reacted with recombinant human IFN-gamma. In in vitro biological studies, the purified IFN-gamma (two mol. wt. species) upregulated the expression of canine class II MHC molecules on dog tubular epithelial cells and the dog kidney epithelial cell line (MDCK). The antidog IFN-gamma mAb blocked T cell proliferative response to kidney cell and, by inference, the interaction between endogenously released IFN-gamma in vitro with its cell surface receptor, thus inhibiting the induced upregulation of class II. Interestingly, although antidog IFN-gamma markedly blocked the MLKC (10 micrograms mAb/well), there was no effect on the allogeneic MLC. This observation indicates that the cytokine IFN-gamma may be a uniquely key substance amplifying the immune response of T cells to tissue-associated antigens on surrogate antigen-presenting cells that require induced upregulation of class II MHC antigen expression (MLKC), in contrast to reactions in which these antigens are already constitutively expressed on the antigen-presenting cells (mixed lymphocyte culture). 相似文献
98.
A Rahmouni A Yang C M Tempany T Frenkel J Epstein P Walsh P K Leichner C Ricci E Zerhouni 《Journal of computer assisted tomography》1992,16(6):935-940
More accurate noninvasive estimation of prostate size is important in therapeutic trials for benign prostatic hyperplasia. The accuracy of MRI and transrectal ultrasound (TRUS) in assessing prostate weight was evaluated in 48 patients who underwent radical prostatectomy for stage A or B cancer. The volume derived from the wet weight of the freshly excised specimen was used as a reference. We compared that volume with volume estimates derived from the three-axis linear dimension measurement by MRI and TRUS using a tissue density of 1.05 g/cc and the standard formula for an ellipsoid object. Prostate and seminal vesicle volumes were also computed by contouring T2-weighted 5 mm thick contiguous MR images using a semiautomatic edge detection program and pixel summation. Three-axis volume MRI method versus volume from wet weight has slightly less scatter than TRUS three-axis method (r = 0.85 vs r = 0.81). Contoured MR volume method has the least scatter r = 0.93, statistically better than the linear axis method. Contoured MRI volumetric analysis appears superior to linear MRI or TRUS methods in estimating true prostate volume. 相似文献
99.
The purpose of the present study was to determine the reliability of several selected signs of trauma from occlusion and their relations with severity of periodontitis. 32 moderate to advanced chronic periodontitis patients participated in the study. All teeth present were evaluated for various abnormal occlusal contacts, signs of trauma from occlusion, and the severity of periodontitis. Standardized periapical radiographs were also taken for each tooth. The results demonstrated that: (1) no significant difference occurred in probing pocket depth (PD), clinical attachment loss (AL), or percentage of alveolar bone height (BH) between teeth with and without various abnormal occlusal contacts, i.e., premature contacts in centric relation occlusion, non-working contacts in lateral excursions, premature contacts of anterior teeth or posterior protrusive tooth contacts; (2) teeth with either significant mobility, functional mobility, or radiographically widened periodontal ligament space (PDLS) had deeper PD, more AL and lower BH than teeth without these signs, while teeth with pronounced wear or radiographically thickened lamina dura had less AL than teeth without these findings; (3) 2 combined indices, i.e., the trauma from occlusion index (TOI) and the adaptability index (AI), were proposed for the identification of occlusal trauma and the response of periodontium to excessive biting forces in heavy function, respectively; TOI-positive teeth exhibit deeper PD, more AL and less osseous support than TOI-negative teeth; however, AI-positive teeth had less AL and more osseous support than AI-negative teeth; (4) with identical attachment level, TOI-positive teeth had less osseous support than TOI-negative teeth while the magnitude of difference became greater with an increase of attachment loss. 相似文献
100.
VEGF和p53在胰腺癌中的表达及意义 总被引:1,自引:0,他引:1
目的 探讨胰腺癌组织中血管内皮生长因子 (VEGF)及p5 3蛋白的表达及其临床病理意义。方法 采用SP免疫组织化学方法 ,对 46例胰腺癌组织中VEGF及 p5 3蛋白的表达进行检测。结果 VEGF与 p5 3表达率分别为 65 .2 %和 5 8.7%。p5 3表达与VEGF表达呈明显正相关(P <0 .0 5 )。VEGF表达与胰腺癌淋巴结转移 (P <0 .0 5 )和远处转移 (P <0 .0 1)显著相关 ,而与肿瘤大小 ,病理学分级无关 ,p5 3表达与胰腺癌远处转移 (P <0 .0 5 )显著相关 ,而与肿瘤大小 ,病理学分级及淋巴结转移无关。结论 在胰腺癌中 ,VEGF表达与 p5 3蛋白的表达呈正相关 ,在胰腺癌的转移中起重要作用 相似文献