全文获取类型
收费全文 | 11067篇 |
免费 | 592篇 |
国内免费 | 90篇 |
专业分类
耳鼻咽喉 | 117篇 |
儿科学 | 172篇 |
妇产科学 | 80篇 |
基础医学 | 1366篇 |
口腔科学 | 147篇 |
临床医学 | 668篇 |
内科学 | 3246篇 |
皮肤病学 | 182篇 |
神经病学 | 817篇 |
特种医学 | 417篇 |
外科学 | 2020篇 |
综合类 | 46篇 |
预防医学 | 269篇 |
眼科学 | 165篇 |
药学 | 687篇 |
中国医学 | 14篇 |
肿瘤学 | 1336篇 |
出版年
2023年 | 66篇 |
2022年 | 115篇 |
2021年 | 277篇 |
2020年 | 149篇 |
2019年 | 199篇 |
2018年 | 251篇 |
2017年 | 226篇 |
2016年 | 286篇 |
2015年 | 303篇 |
2014年 | 383篇 |
2013年 | 415篇 |
2012年 | 689篇 |
2011年 | 700篇 |
2010年 | 393篇 |
2009年 | 409篇 |
2008年 | 683篇 |
2007年 | 758篇 |
2006年 | 723篇 |
2005年 | 728篇 |
2004年 | 684篇 |
2003年 | 650篇 |
2002年 | 642篇 |
2001年 | 158篇 |
2000年 | 130篇 |
1999年 | 144篇 |
1998年 | 149篇 |
1997年 | 105篇 |
1996年 | 88篇 |
1995年 | 101篇 |
1994年 | 81篇 |
1993年 | 59篇 |
1992年 | 105篇 |
1991年 | 80篇 |
1990年 | 68篇 |
1989年 | 70篇 |
1988年 | 61篇 |
1987年 | 64篇 |
1986年 | 56篇 |
1985年 | 57篇 |
1984年 | 38篇 |
1983年 | 31篇 |
1982年 | 35篇 |
1981年 | 19篇 |
1979年 | 38篇 |
1978年 | 22篇 |
1977年 | 20篇 |
1971年 | 21篇 |
1969年 | 19篇 |
1968年 | 27篇 |
1967年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
An invasion-independent pathway of blood-borne metastasis: a new murine mammary tumor model 下载免费PDF全文
Sugino T Kusakabe T Hoshi N Yamaguchi T Kawaguchi T Goodison S Sekimata M Homma Y Suzuki T 《The American journal of pathology》2002,160(6):1973-1980
It is generally believed that active invasion by cancer cells is essential to the metastatic process. In this report, we describe a murine mammary tumor (MCH66) model of metastasis that does not require invasion into the vascular wall of both the primary tumor and the target organ, in this case, the lung. The process involves intravasation of tumor nests surrounded by sinusoidal blood vessels, followed by intravascular tumor growth in the lung, without penetration of the vascular wall during the process. Comparative studies using a nonmetastatic MCH66 clone (MCH66C8) and another highly invasive metastatic cell line (MCH416) suggested that high angiogenic activity and sinusoidal remodeling of tumor blood vessels were prerequisites for MCH66 metastasis. Differential cDNA analysis identified several genes that were overexpressed by MCH66, including genes for the angiogenesis factor pleiotrophin, and extracellular matrix-associated molecules that may modulate the microenvironment toward neovascularization. Our analyses suggest that tumor angiogenesis plays a role in the induction of invasion-independent metastasis. This model should prove useful in screening and development of new therapeutic agents for cancer metastasis. 相似文献
82.
83.
Matsumoto S Sasaki T Imamura A Matsuo K Kayashima T Hashida A Ono S Tsujita T Matsumoto S Nakane Y Tokunaga K Okazaki Y 《American journal of medical genetics》2002,114(1):42-45
Several Caucasian studies and one Japanese study have observed associations between human leukocyte antigen (HLA) class I specificities, including A24 (9) and A26 (10) and schizophrenia. Most of those studies were conducted in 1970s and early 1980s, when the typing technique of HLA was not adequately reliable. Also, an operational diagnostic system was not employed in many of the studies. The present study investigated frequencies of HLA-A specificities in schizophrenia patients (ICD-10 and DSM-III-R, n=98) and sex-matched healthy controls (n=392) from population in the southwestern part of Japan. HLA-B and -C specificities were studied in addition. Frequencies of subjects possessing A24 and A26 were not different between the patients and controls (54% and 24% in the patients and 62% and 24% in the controls, respectively). No significant difference was found in frequencies of other class I (A, B, and C) specificities between the patients and the controls. Thus, the present study provided no evidence for an association between the HLA class I specificities, including A24, A26, and others, and schizophrenia in the Japanese population. 相似文献
84.
Tyrosine hydroxylase (TH)-positive cells and fibers were examined by immunohistochemistry in the chick spinal cord. TH-positive cells, which were located in laminae I, V and X, were most frequently found in the rostral part of the cervical spinal cord, with fewer cells being found in more caudal levels of the spinal cord. TH-positive cells located in lamina X, which were bipolar in shape, were mainly found in regions lateral as well as just ventral to the central canal. They had processes reaching to the central canal. The terminals of these cerebrospinal-fluid-contacting cells were oval in shape, and were most frequently found at the ventral wall of the central canal. There were dense clusters of TH-positive fibers in lamina X. A meshwork-like structure of TH-positive fibers was found over the lateral wall of the central canal. A high density of TH-positive fibers was also found in the medial part of laminae V-VII. In lamina IX, small numbers of TH-positive fibers were observed in the lateral motor column of the brachial spinal cord, and in the medial and lateral motor columns of the lumbosacral spinal cord. However, within the medial motor column of the brachial spinal cord TH-positive fibers were densely distributed around somal as well as dendritic profiles. Similar to our previous observations on serotoninergic fibers. TH-positive fibers were also differentially distributed in the ventral horn of the chicken spinal cord: a high density of TH-positive fibers was localized to specific regions of the spinal motor nucleus. 相似文献
85.
Kawabata A Kawao N Itoh H Shimada C Takebe K Kuroda R Masuko T Kataoka K Ogawa S 《Neuroscience letters》2002,329(3):349-353
Activation of the peripheral protease-activated receptor-2 (PAR-2) triggers nociceptive behaviour and thermal hyperalgesia in rats. The present study created a novel mouse model for PAR-2-triggered nociception, and then examined the roles of NMDA receptors and the nitric oxide (NO) pathway in nociceptive processing by PAR-2. Intraplantar administration of the PAR-2 agonist SLIGRL-NH(2) elicited nociceptive responses in mice, an effect being more specific in mast cell-depleted mice. This PAR-2-triggered nociception was abolished by the NMDA receptor antagonist MK-801, but not the neuronal NO synthase inhibitor 7-nitro indazole. In contrast, the PAR-2-triggered thermal hyperalgesia in rats was blocked by both agents. Our study thus provides a novel mouse model for PAR-2-mediated nociception, and suggests that NMDA receptors are involved in PAR-2-triggered nociception and hyperalgesia, while NO contributes only to the latter. 相似文献
86.
Takaaki Ohmori Kazuyo Okada Ryo Tabei Keisuke Sugiura Shinji Nabeshima Hiroji Ohoka Masaki Okamoto 《Pathology international》1994,44(4):333-337
A case of primary seminal vesicle carcinoma is reported. The tumor was a CA125-producing adenocarcinoma consisting of fine papillary-tubular, intricate branching or anastomosing glandular structures and was composed of small cuboidal, but occasionally hobnailed, cells with mostly clear, but occasionally granular, cytoplasm. Some tumor cells showed evidence of secretion of seromucinous materials into the interpapillary and cystic space. lmmunohistochemically, almost half of the tumor cells expressed a positive reaction with anti-CAl25, a common serological marker for ovarian epithelial carcinomas; however, no tumor cells expressed any other serological tumor markers such as carcinoem-bryonic antigen, α-fetoprotein, human chorionic gonadotropin, prostatic specific acid phosphatase, or prostatic specific antigen. The patient showed a high level of serological CA125, which fluctuated parallel with the growth, removal and recurrence of the tumor. The morphological and immunohistochemical findings suggested a close relationship between the present tumor and clear cell carcinoma of the ovary, which is thought to be of a Müllerian-Wolfian duct origin. 相似文献
87.
Massimo Pignatelli Tareq W. Ansari Pat Gunter Dan Liu Shinji Hirano Masatoshi Takeichi Günter Klppel Nicholas R. Lemoine 《The Journal of pathology》1994,174(4):243-248
Epithelial cadherin (E-cadherin) is a Ca2+-dependent cell-cell adhesion molecule that connects cells via homotypic interactions. Its function is critical in the induction and maintenance of cell polarity and differentiation, and its loss of downregulation is associated with an invasive and poorly differentiated phenotype in colon and other tumours. We have used an avidin-biotin immunoperoxidase technique to localize E-cadherin in microwave-treated, paraffin-embedded sections from 36 patients with pancreatic adenocarcinomas. E-cadherin was expressed by normal ductal and acinar cells with typical membranous staining at the intercellular junctions. Loss of normal surface E-cadherin expression was found in 19/36 (53 per cent) tumours compared to the adjacent normal ductal cells. Abnormal E-cadherin expression was found more frequently in poorly differentiated (grade III) (6/7, 86 per cent) than in well-differentiated tumours (grade I) (4/14, 28 per cent) (P=0·012). Membranous E-cadherin expression was also lost more frequently in primary tumours with lymph node (stage III) (14/23, 61 per cent) and distant metastasis (stage IV) (2/2, 100 per cent) compared with 3/11 (27 per cent) lymph node-negative tumours (stage I) (P=0·043). In conclusions, our data indicate that loss of membranous E-cadherin expression is associated with high grade and advanced stage in pancreatic cancer. 相似文献
88.
89.
Interaction of cholecystokinin (CCK) with vasoactive intestinal peptide (VIP) in body shaking response to ice-water immersion was observed in pentobarbital-anesthetized rats. Although CCK itself had no influence on the response, VIP suppressed it and this effect of VIP was antagonized by simultaneous administration of sulfated octapeptide of CCK, but not by non-sulfated CCK. 相似文献
90.
T cell immunity and primary biliary cirrhosis 总被引:4,自引:0,他引:4
T lymphocytes play a pivotal role in the autoimmune response in primary biliary cirrhosis (PBC). Recent studies have shown that there is overlapping in the PDC-E2-specific T and B cell epitopes. In addition, helper T and cytotoxic T cell epitopes all contain a shared peptide sequence. In addition, recognition of exogenous antigens including bacterial antigens by autoantigen-specific T cell and the mechanism of molecular mimicry provide a clue to clarifying the pathogenesis of PBC. Furthermore, the findings that autoantigen-immune complexes cross present and also that the presentation of autoantigen is of a higher relative efficiency, define a unique role of autoantibodies in the pathogenesis of the autoimmune disease. The mechanism of immune-mediated bile duct damage in PBC, including the possible role of T cell-mediated cytotoxicity and molecular mimicry is discussed. 相似文献