全文获取类型
收费全文 | 14961篇 |
免费 | 1999篇 |
国内免费 | 348篇 |
专业分类
耳鼻咽喉 | 389篇 |
儿科学 | 304篇 |
妇产科学 | 294篇 |
基础医学 | 2163篇 |
口腔科学 | 56篇 |
临床医学 | 3600篇 |
内科学 | 1222篇 |
皮肤病学 | 85篇 |
神经病学 | 598篇 |
特种医学 | 632篇 |
外国民族医学 | 16篇 |
外科学 | 1806篇 |
综合类 | 2390篇 |
现状与发展 | 1篇 |
预防医学 | 493篇 |
眼科学 | 205篇 |
药学 | 701篇 |
11篇 | |
中国医学 | 221篇 |
肿瘤学 | 2121篇 |
出版年
2024年 | 45篇 |
2023年 | 238篇 |
2022年 | 434篇 |
2021年 | 631篇 |
2020年 | 667篇 |
2019年 | 603篇 |
2018年 | 564篇 |
2017年 | 675篇 |
2016年 | 814篇 |
2015年 | 726篇 |
2014年 | 1039篇 |
2013年 | 1034篇 |
2012年 | 819篇 |
2011年 | 887篇 |
2010年 | 704篇 |
2009年 | 624篇 |
2008年 | 681篇 |
2007年 | 656篇 |
2006年 | 650篇 |
2005年 | 571篇 |
2004年 | 531篇 |
2003年 | 422篇 |
2002年 | 391篇 |
2001年 | 307篇 |
2000年 | 274篇 |
1999年 | 233篇 |
1998年 | 220篇 |
1997年 | 180篇 |
1996年 | 181篇 |
1995年 | 179篇 |
1994年 | 164篇 |
1993年 | 142篇 |
1992年 | 113篇 |
1991年 | 107篇 |
1990年 | 94篇 |
1989年 | 91篇 |
1988年 | 66篇 |
1987年 | 60篇 |
1986年 | 79篇 |
1985年 | 78篇 |
1984年 | 49篇 |
1983年 | 30篇 |
1982年 | 42篇 |
1981年 | 56篇 |
1980年 | 37篇 |
1979年 | 22篇 |
1978年 | 24篇 |
1977年 | 30篇 |
1976年 | 10篇 |
1975年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 507 毫秒
91.
Louise A. Rollins-Smith Patrick J. Blair A. Tray Davis 《Clinical & developmental immunology》1992,2(3):207-213
Metamorphosis in amphibians presents a unique problem for the developing immune
system. Because tadpoles are free-living, they need an immune system to protect against
potential pathogens. However, at metamorphosis, they acquire a variety of new adultspecific
molecules to which the tadpole immune system must become tolerant. We
hypothesized that Xenopus laevis tadpoles may avoid potentially destructive antiself
responses by largely discarding the larval immune system at metamorphosis and
acquiring a new one. By implanting triploid (3N) thymuses into diploid (2N) hosts, we
examined the influx and expansion of host T-cell precursors in the donor thymus of
normally metamorphosing and metamorphosis-inhibited frogs. We observed that donor
thymocytes are replaced by host-derived cells during metamorphosis, but inhibition of
metamorphosis does not prevent this exchange of cells. The implanted thymuses export
T cells to the spleen. This donor-derived pool of cells declines after metamorphosis in
normally developing frogs but is retained to a greater extent if metamorphosis is
inhibited. These studies confirm previous observations of a metamorphosis-associated
wave of expansion of T cells and demonstrate that it is not dependent on the relatively
high concentrations of thyroid hormones required for metamorphosis. Although some
larval T cells persist through metamorphosis, others may be destroyed or the larval
population is significantly diluted by the expanding adult population. 相似文献
92.
Anti-human thyroid peroxidase and anti-human thyroglobulin antibodies present no cross-reactivity on recombinant peptides.
下载免费PDF全文
![点击此处可从《Clinical and experimental immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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
93.
Fadda G Muie A Rufini V Ardito G Revelli L Fiorino MC Capelli A 《Endocrine pathology》2000,11(4):373-377
Cystic lesions of the thyroid are common findings. Although many thyroid cysts are of benign, some cases of hemorrhagic degenerative
changes occur in neoplastic nodules, mostly follicular neoplasms and papillary carcinomas. The occurrence of hemorrhagic changes
in medullary carcinomas has never been documented with aspirative cytological and histological pictures to the best of our
knowledge. A case of medullary thyroid carcinoma with a large central hemorrhagic cyst is described, and the literature regarding
the pathogenesis of this regression and the occurrence of cystic neoplasms in the thyroid is reviewed. 相似文献
94.
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
95.
根据174例疑诊患者的TMA、TGA,T3,T4放射免疫测定结果及其临床表现进行诊断,结果表明桥本氏甲状腺炎和甲亢所占的比例(分别为38.51%及31.61%)显著高于甲减和亚急性甲状腺炎(分别为6.32%和4.02%),P<0.05。甲减患者TGA TMA的阳性率(81.82%)显著高于甲亢(50.91%),桥本氏甲状腺炎(50.75%)及亚急性甲状腺炎(57.14%),P<0.05。单项抗体阳性者以TMA较TGA为多。本文结果提示在甲状腺疾病中TMA,TGA的阳性结果存在相互重叠现象,与T3、T4联检并结合临床表现进行综合分析有助于甲状腺疾病的鉴别诊断并正确指导治疗。 相似文献
96.
Terry L. Riss Masami Ogasawara Kenneth P. Karey David Danielpour Betty H. Stewart David A. Sirbasku 《Methods in Cell Science》1986,10(2):133-150
Summary Serum-free defined media have been developed for assay of the mitogenic effects of growth factors on human MCF-7, human T-47D, and mouse COMMA-D mammary cells as well as for identification of mitogens and inhibitors of GH4C1 rat pituitary tumor cell growth. These lines were shown to grow in vivo in response to a variety of hormones including estrogens and thyroid hormones. With mammary cells, complete hormonally and nutritionally defined media were established that supported continuous passage at 50 to 90% of the serum stimulated rate. The strategy used to measure mitogens for mammary cells was to identify nutritional conditions where the growth rate was reduced greatly without impairing the response to picomolar to nanomolar concentration of growth factors. The effects of polypeptide growth factors and tissue extracts were estimated by their addition to basal medium and measuring cell number increases or labeled thymidine incorporation into DNA. In a variation of this methodology, the MTW9/PL2 rat mammary cells were used to identify secreted autocrine growth factors; nutritionally defined conditions were sought for growth of these rat cells in the complete absence of exogenous growth factors. The factors secreted into the medium were detected by bioassays with COMMA-D or MCF-7 mammary cell lines. The effects of growth factors-inhibitors on pituitary cells were measured by a related method; the GH4C1 cells were grown at less than optimal rates in a defined medium designated TRM-1. Addition of mitogens to TRM-1 stimulated pituitary cell growth whereas addition of inhibitors caused reduced levels of growth. The methods described in this report offer new means of assaying growth factors-inhibitors for a range of mammary and pituitary tumor cells. 相似文献
97.
Immunostaining of galectin-3 and CD44v6 using fine-needle aspiration for distinguishing follicular carcinoma from adenoma 总被引:4,自引:0,他引:4
To evaluate the clinical applicability of galectin-3 and CD44 variant 6 (CD44v6) immunostaining in fine-needle aspiration cytology (FNAC) of thyroid follicular tumors, 79 cytological specimens (35 follicular carcinomas and 44 follicular adenomas) were studied. The positive rates of galectin-3 and CD44v6 were 89 and 74% in follicular carcinoma, respectively, and 25 and 30% in follicular adenoma, respectively. There were no significant correlations between the expression of galectin-3 or CD44v6 in follicular carcinoma and characteristics such as capsular invasion, vascular invasion, metastasis, or tumor size. Positive staining of either galectin-3 or CD44v6 resulted in a diagnostic sensitivity of 97% and a specificity of 52% for follicular carcinoma among follicular tumors. Immunostaining of galectin-3 or CD44v6 using cytological specimens can provide independent information on conventional morphological findings of cytology to distinguish follicular carcinoma from adenoma. 相似文献
98.
Ya. Kh. Turakulov N. S. Salakhova T. P. Tashkhodzhaeva S. I. Mirmakhmudova N. M. Mullagalieva Sh. F. Karimova 《Bulletin of experimental biology and medicine》1978,86(6):1575-1577
The effect of potassium iodide and perchlorate was studied on parameters characterizing the secretion of thyroid hormones: the cyclic AMP level in the thyroid gland tissue and the number of intracellular colloid drops during stimulation with thyroid hormones. Excess of iodide was shown to depress these indices whereas perchlorate prevented the inhibitory effect of iodide. The results support the view that the adenylate-cyclase system of the thyroid gland is sensitive to the organic iodine concentration. Excess of iodide evidently reduces the ability of perchlorate to affect its concentration in the gland, so that the process of organification of iodine and the secretion of thyroid hormones are maintained at the optimal level.Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 12, pp. 653–655, December, 1978. 相似文献
99.
100.
Adhesion molecule expression in Graves'' thyroid glands; potential relevance of granule membrane protein (GMP-140) and intercellular adhesion molecule-1 (ICAM-1) in the homing and antigen presentation processes.
下载免费PDF全文
![点击此处可从《Clinical and experimental immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
To assess the potential role of adhesion molecules in the pathogenesis of Graves' disease, we examined the expression of several of these adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule (VCAM-1) and granule membrane protein-140 (GMP-140), in sections of Graves' thyroid glands and control thyroids, using immunohistochemical techniques. Up-regulated expression of GMP-140 was frequently observed on endothelial cells (EC) of post-capilliary venules in all Graves' thyroids examined, compared with an occasional weak staining on EC control glands. Some capillary EC around thyroid follicles (perifollicular EC) were strongly positive for GMP-140 in the Graves' thyroids in contrast to a negative staining on the same structures in the control glands. In addition, there was a correlation between the reactivity and frequency of GMP-140 expression on EC and the severity of mononuclear cell (MNC) infiltration in the Graves' thyroids. The expression of ICAM-1 was up-regulated on perifollicular EC and EC of small venules in some thyroids of both Graves' and control groups. Conversely, no significant expression was observed on any type of EC for both endothelial-leucocyte adhesion molecule-1 (ELAM-1) and VCAM-1. However, dendritic-like cells, present within lymphocytic infiltrates, were positive for VCAM-1 in most of the Graves' thyroids examined, especially in those with a severe lymphocytic infiltration. Thyrocytes were constantly negative for the expression of all four adhesion molecules investigated. These data suggest that GMP-140, as well as ICAM-1, could play an important role in the initiation of MNC infiltration in Graves' disease. ELAM-1 and VCAM-1 appear not to be relevant for the migration of MNC from the blood vessels into the target gland, although VCAM-1 expression on dendritic-like cells might play an additively tissue-selective role in autoantigen presentation and subsequent elicitation of autoimmune phenomena. 相似文献