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   25087篇
  免费   2236篇
  国内免费   552篇
耳鼻咽喉   932篇
儿科学   444篇
妇产科学   504篇
基础医学   4150篇
口腔科学   1374篇
临床医学   2425篇
内科学   2125篇
皮肤病学   331篇
神经病学   867篇
特种医学   1048篇
外国民族医学   20篇
外科学   3014篇
综合类   3941篇
现状与发展   1篇
预防医学   893篇
眼科学   893篇
药学   1514篇
  25篇
中国医学   531篇
肿瘤学   2843篇
  2024年   87篇
  2023年   411篇
  2022年   799篇
  2021年   1003篇
  2020年   993篇
  2019年   905篇
  2018年   817篇
  2017年   864篇
  2016年   971篇
  2015年   972篇
  2014年   1535篇
  2013年   1475篇
  2012年   1348篇
  2011年   1411篇
  2010年   1255篇
  2009年   1066篇
  2008年   1099篇
  2007年   1069篇
  2006年   1003篇
  2005年   894篇
  2004年   789篇
  2003年   698篇
  2002年   571篇
  2001年   562篇
  2000年   481篇
  1999年   441篇
  1998年   406篇
  1997年   381篇
  1996年   359篇
  1995年   322篇
  1994年   279篇
  1993年   278篇
  1992年   233篇
  1991年   227篇
  1990年   203篇
  1989年   196篇
  1988年   162篇
  1987年   133篇
  1986年   151篇
  1985年   153篇
  1984年   147篇
  1983年   73篇
  1982年   114篇
  1981年   120篇
  1980年   105篇
  1979年   61篇
  1978年   63篇
  1977年   57篇
  1976年   35篇
  1975年   34篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
本文对20例20~36周引产死胎胸腺进行了解剖学,组织学观察,并应用吻合血管胎儿胸腺移植治疗晚期恶性原发及继发骨肿瘤12例。结果表明,胎儿胸腺的血供主要来自胸廓内动脉,其次为甲状腺下动脉和心包膈动脉胸腺支,7~8个月胎儿胸腺静脉血管壁较厚,适合作血管吻合,胸腺细胞发育成熟,组织结构正常,已有分泌胸腺素及转化免疫细胞的功能,在解剖学,组织学,免疫学方面均具备了良好的移植条件。12例接受吻合血管胎儿胸腺移植的晚期恶性骨肿瘤患者,其临床症状、体征、X线、免疫指数均有明显改善,患者生存6个月至37个月以上。  相似文献   
42.
Abstract Thyroid hormones were measured before, during and after acute exercise (60 min) or physical training (3 months) in obese women. Thyroid stimulating hormone concentration increased during acute work and decreased immediately after. No changes were seen during the two following days. An increase was seen after ten days as well as after three months of physical training. Thyroxine concentrations showed no changes. 3,5,3′-Triiodothyronine decreased slightly immediately after acute exercise, and after three months of physical training, 3,3′,5′-triiodothyronine (reverse triiodothyronine) increased slowly during and after acute exercise. A negative correlation was found between changes in fasting insulin and thyroxine and a positive correlation between changes in blood pressure and triiodothyronine after training. Lack of agreement in previous reports is probably due to methodological differences such as methods more or less susceptible to fatty acid interference, and thyroid hormones changing differently during acute work and before and after physical training. The duration of the study may also be of importance, even 3 months possibly being too short for attaining equilibrium in thyroid homeostasis.  相似文献   
43.
对205例甲状腺手术进行分析,其发病情况与资料报道基本相符。各种并发症的发生率未超过1%,无手术死亡,术后无甲状腺危象发生,与60年代以前相比已大为降低。  相似文献   
44.
Primary squamous cell carcinoma of the submandibular gland is a rare tumor. In this report, the histological and ultrastructural features of a case of primary squamous cell carcinoma arising in the left submandibular gland is presented. Light microscopically, the tumor consisted of well differentiated keratinizing squamous cell nests. Ultrastructurally, the tumor cells were oval or spindle-shaped, and several tumor cells had intracytoplasmic desmosome-like structures, resembling intercellular desmosomes. The majority of the tumor cells contained a large number of intermediate filaments (tonofilaments). Intercellular desmosomes were well developed. No secretory granules were found. These ultrastructural features may enable us to distinguish primary squamous cell carcinoma from mucoepidermoid carcinoma which is often misdiagnosed as squamous cell carcinoma.  相似文献   
45.
目的:探讨保留甲状软骨膜对全喉切除手术进程和病人术后恢复情况的影响。方法:在甲状软骨膜下游离甲状软骨并切断其上角。不结扎和切断舌骨下肌群和喉上动脉。保留之甲状软骨膜用以加强修复咽壁黏膜。结果:本组病例较经典全喉切除术手术时间缩短30min以上。手术中出血在100ml以下。患者术后第2d下床活动,第4d开始进食流质。手术创口均一期愈合。结论:全喉切除术中保留甲状软骨膜可有效地简化手术步骤,减少创伤和出血。利用甲状软骨膜加强咽壁黏膜缝合口,进一步减少了咽漏的发生.  相似文献   
46.
Thyroglobulin (Tg) and thyroid peroxidase (TPO) are two antigens largely recognized by the sera from patients with autoimmune thyroid disease (AITD). Recently, the complete mapping of both antigens was established with rabbit polyclonal antibodies by the use of recombinant proteins expressed in prokaryotic vector. Several investigators have argued for the existence of a cross-reactivity of some hetero- and autologous antibodies versus these two proteins. In the present study, using rabbit polyclonal antibody, mouse polyclonal antibody and autoimmune antibody (aAb), we observed no common epitope on human Tg (hTg) and human TPO (hTPO).  相似文献   
47.
We have studied 3 cases of sarcoidosis involving the parotid gland by means of fine-needle aspiration cytology (FNAC). The main findings were noncaseating granulomas, multinucleated giant cells (MGCs), and lymphocytes. In one case MGCs contained asteroid bodies and in another case we observed calcium oxalate crystals (COCs) over both stromal fragments and MGCs. Although nonpathognomonic for sarcoidosis, these 2 findings may help in the diagnosis of this condition. However, both are easily overlooked and must be borne in mind when viewing noncaseating granulomas. Sarcoid granulomas displaying COC must be differentiated from foreign-body granulomas. The aforementioned cytological findings must be assessed in conjunction with clinical findings. Nevertheless, in most cases the diagnosis of sarcoidosis is made by exclusion.  相似文献   
48.
Our objectives were to study the types and incidence of thyroid follicular lesions coexisting with Hashimoto's thyroiditis (HT), the pitfalls in their cytodiagnosis, and the effect on management. All cases of HT diagnosed by fine-needle aspiration (FNA) and/or histology over a 7-yr period were retrospectively studied. HT coexisted with follicular adenoma (FA) in 6 cases, follicular variant of papillary carcinoma (FVPC) in 1 case, and goitrous nodule (GN) in 2 cases. The overall incidence rates of thyroid neoplasm and goitrous nodules coexistent with HT were 15% and 3.5%, respectively. A preoperative FNA diagnosis was available in 10 histologically proven cases of HT. A false-positive diagnosis of follicular neoplasm (FN) that led to unnecessary thyroidectomies was given in 3 cases. In 2 of these, the cytological diagnosis was HT with the possibility of coexisting FN, and in the third case, the cytological finding of HT was misinterpreted as FN. The main causes of these diagnostic pitfalls were the presence of hyperplastic follicular cells with nuclear pleomorphism, a paucity of lymphoid cells in burned-out HT, and lack of ones exposure. Nuclear pleomorphism was observed in none of the follicular adenomas. FNA diagnosed accurately the coexisting lesions in 6 cases; 3 FA, 1 FVPC, and 2 GN, but it did not sample HT. In one case, FNA diagnosed correctly both HT and the coexisting FA. Therefore, the presence of a coexistent neoplasm or goitrous nodule reduced the chances of sampling HT by 85.7%, with no false-negative results. Indeed, aspiration on and around the thyroid nodule helps in sampling HT. However, HT may dominate the smear and obscure neoplasia. This can be avoided if the procedure is performed by the pathologist and the aspiration is done on the nodule only. The overlapping cytological features of FN and HT were the main causes of false-positive results. This can be reduced by avoiding the diagnosis of FN in the presence of follicular-cell pleomorphism and/or moderate to excessive numbers of lymphoid cells, provided proper aspiration technique is maintained.  相似文献   
49.
A pituitary tumour composed of well-differentiated corticotrophs and adrenocortical cells is reported. Sections of the tumour revealed a mixture of small round cells with amphophilic or basophilic periodic acid-Schiff (PAS)-positive cytoplasm and large spherical and oval cells with abundant, granular, partly vacuolated PAS-negative cytoplasm. The small cells contained type 1 cytokeratin-positive microfilaments, numerous 250–500 nm endocrine-type secretory granules immunoreactive for adenocorticotropic hormone (ACTH) and -lipotropin. The large cells possessed ample cytoplasm filled with abundant vesicular smooth endoplasmic reticulum, numerous mitochondria possessing tubulovesicular cristae and frequent dense bodies. They lacked the features of pituitary endocrine cells or folliculostellate cells and were found to contain a panel of steroidogenic dehydrogenases and hydroxylases. The tumour was classified as a choristoma, in which two distinct cells types, corticotrophs and adrenocortical cells, were mixed. We suggest that, under continued ACTH stimulation, uncommitted stem cells may differentiate into adrenocortical cells. Alternatively, the presence of adrenocortical cells may be the result of heterotopia.  相似文献   
50.
Intending to clarify the true Incidence of Invasive lobular carcinoma of the breast In Japanese women as well as the frequency of unilateral multlcentriclty, 362 cases of clinically defined monocentrlc breast cancer without pre-operative biopsy (previously fine needle aspiration or needle biopsy were routinely carried out for every case) were examined by whole mammary gland serial sectioning. On the basis of pathology and the World Health Organization classification of breast tumors, each case was assigned to one of two main histologlc types: Invasive lobular carcinoma (ILC) or Invasive ductal carcinoma (IDC). Invasive lobular carcinoma was further separated into classic and variant types by employing previously published criteria. Twenty-one cases of ILC (5.8%) were diagnosed, which Is more than In most previous Japanese studies. Unilateral multicentric breast carcinoma was detected In 9.5% of ILC and 16.1% of IDC (the difference was found not significant). Microscopically, ILC tumors were found to be, on average, larger than IDC. Patients with classic type ILC tended to be younger than those with variant type or IDC. Estrogen receptor expression was found more frequently In variant type ILC than in classic type. These results suggest that the incidence of invasive lobular carcinoma of the breast In Japanese women is low and that unilateral multicentricity Is not significantly higher in ILC than in IDC.  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