全文获取类型
收费全文 | 16375篇 |
免费 | 1078篇 |
国内免费 | 398篇 |
专业分类
耳鼻咽喉 | 674篇 |
儿科学 | 163篇 |
妇产科学 | 137篇 |
基础医学 | 2945篇 |
口腔科学 | 1397篇 |
临床医学 | 1185篇 |
内科学 | 2016篇 |
皮肤病学 | 270篇 |
神经病学 | 991篇 |
特种医学 | 758篇 |
外国民族医学 | 9篇 |
外科学 | 1955篇 |
综合类 | 1995篇 |
现状与发展 | 2篇 |
预防医学 | 255篇 |
眼科学 | 736篇 |
药学 | 730篇 |
7篇 | |
中国医学 | 291篇 |
肿瘤学 | 1335篇 |
出版年
2024年 | 30篇 |
2023年 | 220篇 |
2022年 | 407篇 |
2021年 | 549篇 |
2020年 | 516篇 |
2019年 | 471篇 |
2018年 | 449篇 |
2017年 | 472篇 |
2016年 | 449篇 |
2015年 | 531篇 |
2014年 | 851篇 |
2013年 | 847篇 |
2012年 | 757篇 |
2011年 | 790篇 |
2010年 | 784篇 |
2009年 | 737篇 |
2008年 | 758篇 |
2007年 | 735篇 |
2006年 | 713篇 |
2005年 | 668篇 |
2004年 | 581篇 |
2003年 | 509篇 |
2002年 | 428篇 |
2001年 | 435篇 |
2000年 | 359篇 |
1999年 | 373篇 |
1998年 | 305篇 |
1997年 | 322篇 |
1996年 | 311篇 |
1995年 | 242篇 |
1994年 | 219篇 |
1993年 | 212篇 |
1992年 | 176篇 |
1991年 | 182篇 |
1990年 | 166篇 |
1989年 | 156篇 |
1988年 | 143篇 |
1987年 | 104篇 |
1986年 | 115篇 |
1985年 | 114篇 |
1984年 | 117篇 |
1983年 | 61篇 |
1982年 | 89篇 |
1981年 | 100篇 |
1980年 | 77篇 |
1979年 | 46篇 |
1978年 | 46篇 |
1977年 | 32篇 |
1976年 | 31篇 |
1975年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
Ectopic pituitary adenoma (EPA) is rare and, to the authors’ knowledge, its association with peliosis has not yet been described.
The case of a 38-yr-old woman with clinical and biochemical evidence of Cushing’s syndrome is reported. Magnetic resonance
imaging (MRI) disclosed a normal pituitary and a separate mass in the sphenoid sinus. The surgically remove’s hyaline change
in the corticotrophs, indicating exposure to glucocorticoid excess. By histology, the mass in the sphenoid sinus was a congested,
chromophobic, partly basophilic, periodic acid-Schiff (PAS)-positive pituitary adenoma composed of pleomorphic, adrenocorticotropic
hormone (ACTH)-positive, corticotrophs. There was focal immunopositivity for MIB-1 and proliferating cell nuclear antigen
(PCNA). Electron microscopy confirmed the diagnosis of corticotroph adenoma. A striking finding, consistent with the diagnosis
of peliosis, was the presence of multiple large blood-filled spaces lacking an endothelial lining. The capillaries were dilated,
but often appeared empty and the fenestrated endothelium exhibited discontinuities. The cause of peliosis is obscure. It may
be that the venous outflow was impaired in this case leading to capillary dilation, congestion, hyperpermeability, rupture,
and accumulation of blood in extravascular spaces. 相似文献
162.
M. Mori R. Chiba F. Tezuka M. Kaji T. Takahashi T. Nukiwa T. Kokubo 《Virchows Archiv : an international journal of pathology》1996,428(3):195-200
Papillary adenoma of type II pneumocytes is a rare tumour. It is considered to be a benign neoplasm and is derived from immature cells in the bronchioloalveolar epithelium, however, its biological nature has not been elucidated. We report a case of an adenomatous tumour; a papillary adenoma of type II pneumocytes, which we regard as possessing malignant potential. Light microscopically, as well circumscribed, papillary tumour of predominantly cuboidal cells resembling type II pneumocytes was found, but Clara type and ciliated cells were also present. Immunohistochemically, the tumour cells reacted positively with antibodies to surfactant apoproteins (A, B), carcinoembryonic antigen, cytochrome P-450 1A1-2 and 2B1-2. Ultrastructurally, many osmiophilic lamellar bodies and electron-dense granules were demonstrated. Semi-serial sections revealed signs of transbronchial dissemination and vascular invasion. Morphometry using 12-dimensional cluster analysis disclosed features of the tumour cells which resembled those of pneumocyte type II adenocarcinoma. These findings suggest that the present case has some malignant characteristics and originates from immature bronchiolar or alveolar cells, with a potential to develop into both type II pneumocyte and Clara cell type adenocarcinomas. 相似文献
163.
采用墨汁硝酸银水溶液局部动脉灌注方法,研究了胎儿、犬和家兔肾上腺(总计80例)器官内的淋巴管.所见结果表明:胎儿和犬肾上腺被膜内及腺体内的较粗大静脉周围存在淋巴管和毛细淋巴管;家兔肾上腺的淋巴管仅分布于被膜内;在肾上腺皮质和髓质的实质内,无论胎儿、犬和兔,仅有血管并无淋巴管或毛细淋巴管. 相似文献
164.
An immunohistochemical study of bone morphogenetic protein in pleomorphic adenoma of the salivary gland 总被引:4,自引:0,他引:4
Yang Lianjia Jin Yan Nakamine Hitoshi Sumitomo Shinichiro Kamegai Akihide Mori Masahiko 《Virchows Archiv : an international journal of pathology》1993,422(6):439-443
Bone morphogenetic protein (BMP) is a potent induction factor for new bone formation including heterotopic chondro-ossification in soft tissues. The immunohistochemical reaction for BMP was studied in 23 cases of pleomorphic adenoma of salivary gland by using a monoclonal antibody produced by hybridoma technique. Positive BMP immunoreactivity was seen in 87% of tumours. Immunohistochemical expression of BMP was observed in modified myoepithelial cells (88% cases), luminal tumour cells of tubulo-ductal structures (78% cases) and chondroid cells in hyaline tissue (22% cases). The authors concluded that the simultaneous presence of glycosaminoglycans as matrix substance and S-100 protein for calcium signalling are associated with BMP-mediated cellular activity of modified myoepithelial cells in the formation of chondroid structures in pleomorphic adenomas of the salivary glands. 相似文献
165.
Yoshitaka Saito Terutaka Ozawa Akinori Nishiyama 《Pflügers Archiv : European journal of physiology》1990,417(4):382-390
Kinetic properties of the Na+-H+ antiport in the acinar cells of the isolated, superfused mouse lacrimal gland were studied by measuring intracellular pH (pHi) and Na+ activity (aNai) with the aid of double-barreled H+- and Na+-selective microelectrodes, respectively. Bicarbonate-free solutions were used throughout. Under untreated control conditions, pHi was 7.12±0.01 and aNai was 6.7±0.6 mmol/l. The cells were acid-loaded by exposure to an NH
4
+
solution followed by an Na+-free N-methyl-d-glucamine (NMDG+) solution. Intracellular Na+ and H+ concentrations were manipulated by changing the duration of exposure to the above solutions. Subsequent addition of the standard Na+ solution rapidly increased pHi. This Na+-induced increase in pHi was almost completely inhibited by 0.5 mmol/l amiloride and was associated with a rapid, amiloride-sensitive increase in aNai. The rate of pHi recovery induced by the standard Na+ solution increased in a saturable manner as pHi decreased, and was negligible at pHi 7.2–7.3, indicating an inactivation of the Na+-H+ antiport. The apparent K
m for intracellular H+ concentration was 105 nmol/l (pH 6.98). The rate of acid extrusion from the acid-loaded cells increased proportionally to the increase in extracellular pH. Depletion of aNai to less than 1 mmol/l by prolonged exposure to NMDG+ solution significantly increased the rate of Na+-dependent acid extrusion. The rate of acid extrusion increased as the extracellular Na+ concentration increased following Michaelis-Menten kinetics (V
max was 0.55 pH/min and the apparent K
m was 75 mmol/l at pHi 6.88). The results clearly showed that the Na+-H+ antiport activity is dependent on the chemical potential gradient of both Na+ and H+ ions across the basolateral membrane, and that the antiporter is asymmetric with respect to the substrate affinity of the transport site. The data agree with the current model of activation and inactivation of the antiporter by an intracellular site through changes in the intracellular Na+ and H+ concentrations. 相似文献
166.
A 22-year-old woman with Cushing's syndrome, caused by an extremely rare suprasellar ectopic pituitary adenoma, is presented. Magnetic resonance imaging and computed tomography revealed a well-circumscribed mass in the right suprasellar region. Endocrinological tests showed elevated s-adrenocorticotropic hormone level and hypercortisolemia. The tumor was totally removed by right subfrontal approach. At the time of the operation, the tumor was in continuity with the distal pituitary stalk but not with the pituitary gland. The diaphragma sellae was intact. Histologic diagnosis of the tumor specimen was confirmed as a pituitary adenoma. After surgical removal of the tumor, continued improvement in the patient's laboratory results and disappearance of her endocrine symptoms strongly indicated the absence of adenoma cells in the pituitary gland or stalk. Six years post-surgery, there was no evidence of recurrence in the patient's clinical and laboratory examination. This tumor probably originated from aberrant anterior pituitary cells of the pituitary stalk. 相似文献
167.
J. Bijman D. I. Cook C. H. van Os 《Pflügers Archiv : European journal of physiology》1983,398(2):96-102
We have studied the response of the rabbit mandibular main duct perfused in vitro to luminally administered amiloride. The half-maximal inhibitory concentrations (KI) when the duct was bathed in Cl solutions were: for net Na+ transport, 3×10–6 mol l–1; for transepithelial potential difference, 6×10–6 mol l–1; and for transepithelial conductance, 3×10–7 mol l–1. Substitution of the impermeant SO
4
2–
anion for Cl– changed the KI for conductance to 3×10–6 mol l–1. Within Cl–-containing media, the time course of the amiloride effect on potential difference showed an early rapid fall of 10 mV with a half-time 2 s, followed by a slower depolarization of 9 mV, and the conductance change followed the slower component of the potential change. In SO
4
2–
-containing media, the potential difference and conductance changes followed time courses similar to one another. Finally, experiments on the effect of serosal applications of ouabain revealed that, although, in general, ouabain reduced resistance, it caused an increase in resistance in those ducts where the initial resistance was low. We conclude that: i) luminal Na+ transport occurs via amiloride-sensitive, conductive Na+ channels; ii) the Cl– conductance is the major determinant of transepithelial conductance; iii) the first phase of the potential response is due to blocking of the Na+ conductive channels, whilst the slow phase reflects secondary inhibition of an electrogenic Na+ pump; and iv) duct resistance changes are secondary to alterations in intracellular Cl– concentration. 相似文献
168.
Kazuo Takei Hidenobu Watanabe Takao Itol Toshihiko Saito 《Pathology international》1996,46(11):908-917
Twenty lntramucosal tumors of ‘carclnomaln-adenoma’ and 43 ademas (39 pylorlc gland type, 4 Intestinal type) of the gall-bladder were studied to establish more precise histo-logical criteria of carcinoma or adenoma In cases of ‘carcinoma In pyforic gland type adenoma’, to compare carcinoma In adenoma with pure, that Is, without adenomatous components, carcinoma, and to confirm the benign nature of spin-dle cell fd in the adenomas. Ki-67 and p53 immunostaining and nuclear morphomety were used. Eight pure intramucessl cancers were used as controls. The formalin-fixed, paraffln+mbedded sections were stained with p53 and Ki-67 antibodies. Splndle cell foci were observed only In the adenoma area of the pyloric gland type, wlth a frequency of 23% In 39 adenomas, and of 45% in 20 tumors of carclnoma-lrradenoma. Ki-67 staining was negative in 129 of 130 spin-die cell foci examlned, regardless of their size, and positive in only one focus (550 pm in size, Ki-67 Index 0.2%). All of the spindle cell foci were negative for p53 stain. The Ki-67 positive index was 36.6 ± 5.6% In the 8 pure carcinomas, and 12.5 ± 1.9% in the cancer areas of 16 tumors with carcinoma-in-adenoma, while it was 7.9 ± 1.7% in the adenoma areas of 16 tumors with carcinoma-in-adenoma and 4.9 ± 0.5% in the 32 pure pyloric gland adenomas. The p53-protein over-expression was found in seven of eight pure intramucosal cancers, and in one of 16 cancer components of carclnoma-in-adenoma. However, it was not found in any of 16 adenoma components of carcinoma-in-adenoma, and 35 adenomas. Cells of the cancer tissue of carcinoma-In-adenoma showed a significantly larger nuclear area and a larger nuclear minor axis than those of the pyloric gland type adenomas, as well as other architectural and cytologic abnormalities differing from the features of adenomas. These results suggest that clustered spindle cells do not indmte a malignant transformation of adenoma cells and that carcinomas in carcinoma-in-adenoma are dtfferent from pylorlc gland type adenomas In terms of morphology and proliferative activity. Moreover, the results of the present study indicate that carcinomas In carcinoma-ln-adenoma are lower In malignancy than pure carcinomas, and that their genetic abnormaltty may differ from that of pure carcinomas. 相似文献
169.
170.
p53 immunoreactivity in hepatocellular adenoma, focal nodular hyperplasia, cirrhosis and hepatocellular carcinoma 总被引:2,自引:0,他引:2
I. OJANGUREN A. ARIZA E.M. CASTELLÀ A. FERNÁNDEZ-VASALO J.L. MATE J.J. NA VAS-PALACIOS 《Histopathology》1995,26(1):63-68
The prolonged half-life of mutant p53 makes feasible its immunocytochemical detection. In order to assess the pathogenetic role of mutant p53 in regenerative and neoplastc liver disease we studied its immunohistochemical expression in cases of hepatic cirrhosis, hepatocellular carcinoma (HCC), cirrhosis with areas of HCC, hepatocellular adenoma and focal nodular hyperplasia. The study included needle and wedge biopsies of 50 cirrhotic livers, 59 HCCs (36 of them with associated cirrhosis), six adenomas and two focal nodular hyperplasias. Sixty-five HCC fineneedle cytology specimens were also included in the study. There was no immunohistochemical evidence of mutant p53 expression in any of the cases of cirrhotic liver (except for one instance associated with HCC) adenoma or focal nodular hyperplasia. In contrast p53 was detected in 8.5% of HCC cases in the biopsy series and 24% of HCC cases in the fine needle aspiration series. In addition, mutant p53 expression in HCC was positively correlated with tumour grade. According to grade, the distribution of p53 positive immunoreactivity among HCCs was as follows: Grade I-II, 0% of cases in the biopsy series and 9% in the fine needle aspirates; Grade III, 18% in the biopsy series and 55% in the fine needle aspirates; and Grade IV, 40% in the biopsy series. Therefore, mutant p53 expression does not seem to be associated with benign liver lesions but seems to correlate with the progression of HCC through various grades of increasing malignancy. 相似文献