全文获取类型
收费全文 | 4731篇 |
免费 | 267篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 55篇 |
儿科学 | 70篇 |
妇产科学 | 65篇 |
基础医学 | 617篇 |
口腔科学 | 155篇 |
临床医学 | 364篇 |
内科学 | 1431篇 |
皮肤病学 | 95篇 |
神经病学 | 420篇 |
特种医学 | 117篇 |
外科学 | 650篇 |
综合类 | 22篇 |
一般理论 | 1篇 |
预防医学 | 264篇 |
眼科学 | 68篇 |
药学 | 298篇 |
中国医学 | 11篇 |
肿瘤学 | 332篇 |
出版年
2023年 | 31篇 |
2022年 | 90篇 |
2021年 | 100篇 |
2020年 | 71篇 |
2019年 | 76篇 |
2018年 | 115篇 |
2017年 | 73篇 |
2016年 | 91篇 |
2015年 | 114篇 |
2014年 | 174篇 |
2013年 | 204篇 |
2012年 | 328篇 |
2011年 | 317篇 |
2010年 | 187篇 |
2009年 | 170篇 |
2008年 | 310篇 |
2007年 | 320篇 |
2006年 | 281篇 |
2005年 | 321篇 |
2004年 | 295篇 |
2003年 | 271篇 |
2002年 | 227篇 |
2001年 | 49篇 |
2000年 | 39篇 |
1999年 | 42篇 |
1998年 | 37篇 |
1997年 | 35篇 |
1996年 | 37篇 |
1995年 | 46篇 |
1994年 | 33篇 |
1993年 | 27篇 |
1992年 | 38篇 |
1991年 | 30篇 |
1990年 | 34篇 |
1989年 | 23篇 |
1988年 | 18篇 |
1987年 | 33篇 |
1986年 | 28篇 |
1985年 | 21篇 |
1984年 | 32篇 |
1983年 | 22篇 |
1982年 | 21篇 |
1981年 | 15篇 |
1980年 | 12篇 |
1979年 | 19篇 |
1977年 | 14篇 |
1975年 | 15篇 |
1974年 | 19篇 |
1973年 | 13篇 |
1969年 | 9篇 |
排序方式: 共有5035条查询结果,搜索用时 31 毫秒
41.
Desantis S Corriero A Acone F Zubani D Cirillo F Palmieri G De Metrio G 《Acta histochemica》2003,105(1):73-79
Expression of sugar residues and the nature of oligosaccharide linkage during keratinocyte maturation in the epidermis of the Breton dog were studied with the use of lectin histochemistry. Thirteen lectins were used. Labelling was not observed with GSA I-B4, GSA II, UEA-I, and LTA. The cytoplasm of keratinocytes reacted with PNA, HPA, Con A, and WGA from the basal layer to the granular layer. PNA and Con A showed highest reactivity in the granular cell layer. The cell surface showed increased reactivity with PNA, HPA, and WGA with maturation of keratinocytes. KOH-neuraminidase treatment (KOH-Neu) increased PNA and RCA120 staining during keratinocyte differentiation thus indicating an increase in oligosaccharides terminating with sialic acid-Galbeta(1,3)GalNAc and sialic acid-Galbeta(1,4)GlcNAc, respectively. Labelling of the glycocalyx of basal and spinous keratinocytes with SNA and MAA revealed terminal Neu5acalpha(2,6)Gal/GalNAc and Neu5acalpha(2,3)Galbeta(1,4)GlcNAc. KOH-Neu-DBA showed oligosaccharides terminating with sialic acid-GalNAcalpha(1,3)GalNAc in the spinous and granular layers. A selective glycocalyx labelling of granular keratinocytes was observed with DBA and SBA. Reactions with MAA, PNA, DBA, RCA120, SBA, HPA, and WGA disappeared after the beta-elimination reaction. Our findings indicate that Breton dog epidermis contains more O-linked than N-linked oligosaccharides and confirm that different subpopulations of keratinocytes can be distinguished by lectin histochemistry. 相似文献
42.
Dpc4 is expressed in virtually all primary and metastatic pancreatic endocrine carcinomas 总被引:2,自引:0,他引:2
Scarpa A Orlandini S Moore PS Lemoine NR Beghelli S Baron A Falconi M Zamboni G 《Virchows Archiv : an international journal of pathology》2002,440(2):155-159
DPC4/Smad4 is inactivated in about 50% of pancreatic ductal cancers. It has been recently reported that this gene is also inactivated in neoplasms arising from pancreatic islet cells, a phenomenon suggested to be related to similar progressions of malignancy found in common ductal cancers. To evaluate this possibility, we analysed 20 metastases of pancreatic endocrine carcinomas and their corresponding primary lesion for inactivation of DPC4 using immunohistochemical staining. In fact, immunohistochemical labelling has been shown to correlate with DPC4 gene status with high sensitivity and specificity. The cancers included 18 nonfunctioning tumours, one gastrinoma and one ViPoma all with liver, nodal and/or adrenal metastases. Seventeen were well-differentiated and three poorly differentiated endocrine carcinomas. Dpc4 expression was absent in only one primary well-differentiated endocrine cancer and its liver metastasis, while all the remaining 19 primary tumours and their metastases stained positive for the protein. All positively staining cases showed diffuse cytoplasmic and nuclear staining in virtually all neoplastic cells. Our data suggest that DPC4 is only rarely involved in pancreatic endocrine tumourigenesis and give further weight to the hypothesis that tumours arising from pancreatic exocrine and endocrine epithelia are genetically distinct. 相似文献
43.
Calorini L Mannini A Bianchini F Mugnai G Balzi M Becciolini A Ruggieri S 《Clinical & experimental metastasis》1999,17(10):889-895
A previous study by our laboratory showed that the peritoneal murine Corynebacterium parvum-elicited macrophages released into their growth medium an activity which enhanced the ability of B16-F10 melanoma cells to
form experimental metastases in the lung of syngeneic mice. In the present study, we used a clone of B16-F10 line (F10-M3
cells) to investigate whether the increase in lung-colonizing potential due to the pro-clonogenic activity released by C. parvum-elicited macrophages was associated with biological properties characteristic of a metastatic phenotype. We have found that
the pulmonary retention, growth rate in lung parenchyma, invasiveness through Matrigel, adhesiveness to IL-1-activated endothelium
and MHC class I expression were increased in F10-M3 cells stimulated by the macrophage pro-clonogenic activity. By using an
in vitro experimental protocol, the enhancement of lung-colonizing potential in the stimulated melanoma cells turned out to be a transient
phenomenon as was the increase of invasiveness through Matrigel and the higher expression of MHC class I antigens. In conclusion,
the melanoma cells stimulated by the pro-clonogenic activity released by C. parvum-elicited macrophages showed changes in biological parameters which are relevant to metastatic diffusion. These changes appeared
as a temporary phenomenon which sustains the view that the metastatic phenotype represents a transient biological character
influenced by host factors.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
44.
45.
Sorio C Bonora A Orlandini S Moore PS Capelli P Cristofori P Dal Negro G Marchiori P Gaviraghi G Falconi M Pederzoli P Zamboni G Scarpa A 《Virchows Archiv : an international journal of pathology》2001,438(2):154-158
In order to assess the suitability of cryopreserved neoplastic tissues for xenografting into nude (nu/nu) mice, we compared the take rate in 28 samples of pancreatic ductal carcinoma. Eleven fresh samples were implanted in nu/nu mice, and 17 were frozen in cryopreserving solution and implanted at a later time. All samples were examined for the presence of neoplastic tissue in cryostat sections. A total of 15 tumors grew in the animals; five from the freshly implanted samples and ten from those cryopreserved. Ten xenografted tumors were characterized for alterations in p53, K-ras, and p16 genes, which were found in six, eight, and nine cases, respectively. Our results demonstrate that the take rate for xenografting is comparable between cryopreserved and fresh tissue samples. The procedure allows for the exchange of tumor material between institutions and permits the establishment of centralized facilities for the storage of an array of different primary tumor samples suitable for the production of in vivo models of cancers. 相似文献
46.
Alfredo Vittoria Tiziana Cocca Elena La Mura Aldo Cecio 《Anatomical record (Hoboken, N.J. : 2007)》1992,233(1):18-24
The aim of this study is to describe the presence of neuroendocrine (NE) cells (paraneurons), producing biogenic amines and/or peptidergic hormones, in the female urethra of cattle, sheep, pigs, and horses, by means of histochemical and double labeling immunofluorescent techniques. 5-Hydroxytryptamine-, chromogranin A-, cholecystokinin- and somatostatin-containing NE cells are present in the urethral epithelium of all the species studied, with the unique exception of the lack of somatostatin cells in the horse. Paraneurons containing 5-hydroxytryptamine colocalized with chromogranin A or cholecytokinin were also found in all subjects. Such active substances are hypothesized to play a role in the contraction of the urethral musculature, emission of urogenital fluids, and inhibition of endocrine and exocrine secretions. © 1992 Wiley-Liss, Inc. 相似文献
47.
Cross-platform development of medical applications in extended-reality (XR) head-mounted displays (HMDs) often relies on game engines with rendering capabilities currently not standardized in the context of medical visualizations. Many aspects of the visualization pipeline including the characterization of color have yet to be consistently defined across rendering models and platforms. We examined the transfer of color properties from digital objects, through the rendering and image processing steps, to the RGB values sent to the display device. Five rendering pipeline configurations within the Unity engine were evaluated using 24 digital color patches. In the second experiment, the same configurations were evaluated with a tissue slide sample image. Measurements of the change in color associated with each configuration were characterized using the CIE 1976 color difference (). We found that the distribution of for the first experiment ranges from zero, as in the case using an Unlit Shader, to 25.97, as in the case using default configurations. The default Unity configuration consistently returned the highest across all 24 colors and also the largest range of color differences. In the second experiment, E ranged from 7.49 to 34.18. The Unlit configuration resulted in the highest in three of four selected pixels in the tissue sample image. Changes in color image properties associated with texture import settings were then evaluated in a third experiment using the TG18-QC test pattern. Differences in pixel values were found in all nine of the investigated texture import settings. The findings provide an initial characterization of color transfer and a basis for future work on standardization, consistency, and optimization of color in medical XR applications. 相似文献
48.
Characterisation of bioactive and resorbable polylactide/Bioglass composites by FTIR spectroscopic imaging 总被引:1,自引:0,他引:1
Formation, size and distribution of hydroxyapatite domains in resorbable composites made of poly(DL-lactide) foams and Bioglass particles after exposure to a solution of phosphate-buffer saline (PBS) for different periods of time have been analysed with FTIR imaging using the micro-ATR-IR approach. The spectral information of 4096 spectra measured simultaneously with the IR microscope equipped with a focal plane infrared array detector allowed us to obtain chemical images showing the distribution of Bioglass particles in the composites. FTIR imaging in micro-ATR mode allowed to obtain images with enhanced spatial resolution. A random distribution of hydroxyapatite domains with average size of ca. 10 microm on the surface of the composites was found after exposure to PBS for 14 and 28 days. The further growth of the hydroxyapatite domains after exposure to PBS for 63 days was detected. The spectroscopic imaging method introduced here promises to become a powerful method for characterisation of resorbable polymer composites containing bioactive inorganic phases developed for bone tissue engineering scaffolds. The accurate detection of hydroxyapatite domains and the imaging of their location in the scaffold structure is required to provide an assessment of the composites bioactivity. 相似文献
49.
F Zanardi G Occari L Cavazzini E Grandi A M Tomasi 《Giornale italiano di cardiologia》1986,16(1):4-14
A family with "arrhythmogenic right ventricular dysplasia (ARVD)" is described. ARVD is pathologically characterised by a partial or total degeneration of the right ventricular myocardium, replaced by fatty and fibrous tissue. This causes dangerous ventricular arrhythmias or congestive heart failure in infancy. About the three described patients, a sixteen-year-old subject died suddenly, and his anatomical and histopathological reports have been presented. Familiarity, rarely treated in literature, and the presence, in the died subject, of a damage of the left ventricle too, are the peculiar characteristic of these "ARVD" cases. The importance about instrumental non-invasive studies has been underlined in order to know early "ARVD", which can be deceptive clinically. The authors suppose there is surely, at the beginning of "dysplasia", a genetic alteration of the right cardiac musculature, but acquired noxae could insert afterwards, on this genetic basis. 相似文献
50.