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   5066篇
  免费   206篇
  国内免费   25篇
耳鼻咽喉   90篇
儿科学   126篇
妇产科学   59篇
基础医学   708篇
口腔科学   91篇
临床医学   255篇
内科学   1332篇
皮肤病学   66篇
神经病学   363篇
特种医学   190篇
外科学   738篇
综合类   20篇
预防医学   108篇
眼科学   98篇
药学   404篇
中国医学   36篇
肿瘤学   613篇
  2023年   20篇
  2022年   29篇
  2021年   85篇
  2020年   57篇
  2019年   69篇
  2018年   95篇
  2017年   57篇
  2016年   84篇
  2015年   88篇
  2014年   131篇
  2013年   152篇
  2012年   249篇
  2011年   309篇
  2010年   176篇
  2009年   166篇
  2008年   300篇
  2007年   324篇
  2006年   308篇
  2005年   318篇
  2004年   327篇
  2003年   350篇
  2002年   331篇
  2001年   87篇
  2000年   92篇
  1999年   115篇
  1998年   86篇
  1997年   66篇
  1996年   70篇
  1995年   48篇
  1994年   60篇
  1993年   64篇
  1992年   64篇
  1991年   47篇
  1990年   56篇
  1989年   61篇
  1988年   44篇
  1987年   43篇
  1986年   48篇
  1985年   28篇
  1984年   30篇
  1983年   21篇
  1982年   15篇
  1981年   14篇
  1980年   14篇
  1979年   12篇
  1978年   10篇
  1977年   7篇
  1974年   9篇
  1970年   8篇
  1969年   7篇
排序方式: 共有5297条查询结果,搜索用时 312 毫秒
31.
BACKGROUND: Recently, it is recognized that the patients of oral allergy syndrome (OAS) to fruits are increasing. However, there are little knowledges of the background, character, and seriousness about these patients in Kanto regions. OBJECTIVE: We aimed to investigate the clinical features of OAS patients to plant origin foods in Kanto regions. METHODS: The patient, who visited Sagamihara National Hospital from 2000 to 2005 and developed some allergic symptoms to plant origin foods, were studied by a questionary survey. RESULTS: As for the 42 subjects, average age are 36 years old, male:female=8:34, merger of other allergic disease is 35 allergic rhinitis of 42 subjects (83%), 34 of asthma (81%), 14 of atopic dermatitis (33%). The causes of OAS symptoms are 32 rose-family fruits, 34 non-rose family fruits, 14 vegetables, 11 nuts, 2 grains subjects. As for the symptom, only in the oral and pharynx symptoms are found in 12, the systemic symptoms is 29, anaphylaxis is 11 subjects. Allergic rhinitis preceded on the 90% subjects with pollinosis, very high rate. On the other hand, the 20% of all subjects have no symptoms of allergic rhinitis. CONCLUSION: A nasal catarrh symptoms went ahead in most of the OAS subjects in Kanto regions. In addition, considering from some patients have no black alder pollinosis and/or are allergic to many non-rose-family fruits at high frequency, there might be a broad cross-reactivity between many pollens other than alder and plant origin foods.  相似文献   
32.
The present study was designed to determine whether tumor induction by 3-methylcholanthrene (MC), a carcinogenic hydrocarbon, can be inhibited by oral administration of Lactobacillus casei strain Shirota (LC). C3H/HeN mice were divided into four groups and assigned to the following treatments: treated with MC and given control or LC-containing diet; treated with vehicle only and given control or LC-containing diet. MC (1 mg) was injected intradermally at 7 weeks of age and the tumor incidence was monitored; LC was mixed into a diet at a concentration of 0.05% (w/w) and the diet was fed from the day of MC injection throughout the study. Spleen cells were analyzed for the immune parameters at 12 and 16 weeks after the MC injection. Oral feeding of mice with LC reduced tumor incidence (P < 0.05). MC treatment lowered the in vitro response to concanavalin A (Con A) of spleen cells, the secretion of interleukin-2 in spleen cell culture after stimulation of the cells with Con A and the proportions of CD3+, CD4+ and CD8+ splenic cells. However, the analysis of the spleen cells obtained from the mice treated with MC and given the LC-containing diet revealed that these disrupted host immune parameters were maintained at the level of normal controls. These results suggest that oral feeding of mice with LC inhibits MC-induced tumorigenesis by modulating the disrupted host immune responses during MC carcinogenesis. Received: 14 April 1999  相似文献   
33.
Three cases of pulmonary hypertension caused by tumor emboli to the lungs are described. Two of the three cases had a clinical diagnosis of pulmonary thromboembolism until surgical embolectomy, and the other had a diagnosis of primary pulmonary hypertension. Autopsy disclosed chondrosarcoma, choriocarcinoma and gastric cancer as the primary tumors, respectively. Pulmonary vascular obstruction due to tumor embolism leading to pulmonary hypertension is a previously rare clinical entity, and obstructed pulmonary vessels are believed to tend to be small vessels. We compared the autopsy and radiological findings and concluded that pulmonary tumor embolism involved not only the small peripheral arteries but also the segmental and/or lobar arteries.  相似文献   
34.
To elucidate the involvement of type IV collagenases [matrix metalloproteinase (MMP)-2 and MMP-9] and their tissue inhibitors (TIMP-1 and TIMP-2) in the development of gestational trophoblastic disease (GTD), we quantified their levels in hydatidiform mole and choriocarcinoma tissues using specific enzyme-linked immunosorbent assays, and the results were compared with those from normal first trimester placenta. Levels of pro-MMP-2 were increased in hydatidiform mole, and they were further elevated in choriocarcinoma. Levels of pro-MMP-9 in choriocarcinoma and those of TIMP-1 in both hydatidiform mole and choriocarcinoma were also increased. In contrast, TIMP-2 levels were markedly decreased in both hydatidiform mole and choriocarcinoma. Similar results were obtained by the tissue culture of first trimester placenta and hydatidiform mole. Gelatin zymography indicated that the levels of both pro- and activated forms of MMP-2 and MMP-9 were higher in hydatidiform mole and choriocarcinoma. The decreased expression of TIMP-2 in hydatidiform mole and choriocarcinoma was confirmed by Western blot, Northern blot and immunohistochemistry, with the decrease being more pronounced in choriocarcinoma. Taken together, the present study shows that both TIMP-2 mRNA and protein levels are markedly decreased in GTD and the imbalance of MMP-TIMP production, shifted toward greater MMP activity, may be involved in the pathogenesis of GTD.  相似文献   
35.
Insulin hypersensitivity in mice lacking the V1b vasopressin receptor   总被引:1,自引:0,他引:1  
We have reported that [Arg8]-vasopressin-stimulated insulin release is blunted in islet cells isolated from V1b receptor-deficient ( V1bR −/−) mice. In this study, we used V1bR −/− mice to examine the physiological role of the V1b receptor in regulating blood glucose levels in vivo , and we found that the fasting plasma glucose, insulin and glucagon levels were lower in V1bR −/− mice than in wild-type ( V1bR +/+) mice. Next, we evaluated glucose tolerance by performing an intraperitoneal glucose tolerance test (GTT). The plasma glucose and insulin levels during the GTT were lower in V1bR −/− mice than in V1bR +/+ mice. An insulin tolerance test (ITT) revealed that, after insulin administration, plasma glucose levels were lower in V1bR −/− mice than in V1bR +/+ mice. In addition, a hyperinsulinaemic–euglycaemic clamp study showed that the glucose infusion rate was increased in V1bR −/− mice, indicating that insulin sensitivity was enhanced at the in vivo level in V1bR −/− mice. Furthermore, we found that the V1b receptor was expressed in white adipose tissue and that insulin-stimulated phosphorylation of Akt as an important signaling molecule was increased in adipocytes isolated from V1bR −/− mice. Thus, the blockade of the V1b receptor could result, at least in part, in enhanced insulin sensitivity by altering insulin signalling in adipocytes.  相似文献   
36.
The purpose of this study was to evaluate the in vitro responses to preload and afterload of our total artificial heart (TAH), the MagScrew TAH. The TAH consists of two blood pumps and a control logic, developed at the Cleveland Clinic, OH, and the MagScrew actuator and its electronic control system, developed by Foster-Miller Technologies, Inc., Albany, NY. Tests were performed on a mock circulatory loop, using water as a test fluid. Preload sensitivity of the Mag-Screw TAH demonstrated a Frank-Starling response to preload in automatic mode. A peak flow of 10 L/min was obtained, with a left atrial pressure of 13 mm Hg. The relationship between right atrial pressure and left atrial pressure was well balanced when tested with a left bronchial shunt flow of 5% and a range of pulmonary artery and aortic pressures. With respect to afterload response, the left pump showed a relatively low sensitivity, which allowed the pump to maintain perfusion over a wide range of aortic pressures. The right pump, on the other hand, was much more sensitive to pulmonary artery pressure, which provided a measure of protection against pulmonary congestion. The very effective physiologic response of the MagScrew TAH is believed to result from employment of a left master, alternating ejection control logic, high inherent sensitivity of the blood pumps to atrial pressure, a lower effective stroke volume for the right pump, and a scaling of right side motor ejection voltage to 80% of that used for the left side ejection.  相似文献   
37.
MFG-E8, a secreted integrin-binding protein, consists of two EGF domains containing a RGD motif and two discoidin domains. In mouse embryogenesis, MFG-E8 is highly expressed in gonadal stromal cells near mesonephros at 11.5–12.5 dpc, but its function in gonadogenesis has not been characterized. To clarify a possible role of MFG-E8 in developing gonads, we analyzed the adhesion activity of 10.5–15.5 dpc gonadal cells to recombinant proteins of EGF or discoidin domains of MFG-E8. In EGF-coated wells, the gonadal cells at 11.5–12.5 dpc revealed a significantly higher adhesion activity as compared to those at 10.5 and 15.5 dpc, while discoidin domains showed a constant number of the adhered cells throughout these stages. To identify the adhesive cells of 11.5-dpc gonads, immunohistochemistry with anti-SF1/Ad4Bp antibody (a specific marker for supporting, steroidogenic, and coelomic epithelial cells) and staining for alkaline phosphatase (a germ cell marker) were carried out. As a result, EGF domains, as well as discoidin domains, were capable of binding to all three groups of SF1/Ad4Bp-positive and negative somatic cells, and germ cells of 11.5-dpc gonads. These findings therefore suggest that MFG-E8 mediates the cell-to-cell interaction among several somatic cell types and germ cells in mouse early gonadogenesis.  相似文献   
38.
We report the development of a serodiagnostic method for Mycobacterium avium complex (MAC) disease with an enzyme immunoassay (EIA) with the MAC-specific glycopeptidolipid (GPL) core as the antigen. In this study, we confirmed by EIA that the GPL core antibody was in the sera of immunocompetent patients with MAC disease. The EIA for quantifying the GPL core antibody was evaluated as a clinical tool for serodiagnosis of pulmonary MAC disease. A significant increase in GPL core antibodies (immunoglobulins G, A, and M) was detected in sera of patients with MAC pulmonary diseases when they were compared to patients who were colonized with MAC, patients with Mycobacterium kansasii disease or tuberculosis, and healthy subjects. The sensitivities and specificities of the GPL core-based EIA for diagnosis of MAC pulmonary disease were 72.6% and 92.2%, respectively, for IgG, 92.5% and 95.1%, respectively, for IgA, and 78.3% and 91.0%, respectively, for IgM. The best sensitivity and specificity were obtained by measuring immunoglobulin A antibodies against GPL core antigen. The level of GPL core antibodies reflected disease activity, since it decreased in cured MAC patients who had responded to chemotherapy. Measurement of serum antibodies against GPL core is useful for both diagnosis and assessment of disease activity in MAC disease of the lung.  相似文献   
39.
Porphyromonas gingivalis, the major etiologic agent of chronic periodontitis, produces a broad spectrum of virulence factors, including outer membrane vesicles. In this study, we investigated the capacity of P. gingivalis vesicles to promote the shedding or cleavage of the lipopolysaccharide (LPS) receptor CD14 from the surface of human U937 macrophage-like cells. SDS-PAGE/Western immunoblotting analysis of gingival crevicular fluid samples from patients affected by moderate or advanced periodontitis revealed the presence of soluble CD14 and CD14 fragments, thus supporting the hypothesis of an in vivo shedding and cleavage of CD14 receptors. Flow cytometry analysis of macrophage-like cells treated with a vesicle-containing culture supernatant of P. gingivalis showed a significant decrease in the binding of anti-human CD14 to the cell surface. However, no accumulation of soluble CD14 or immunoreactive CD14 fragments in the assay supernatant could be demonstrated by ELISA. Treatment of macrophage-like cells with various concentrations of P. gingivalis vesicles substantially suppressed TNF-alpha production triggered by Escherichia coli LPS. This suppressive effect was much less important using heat-treated vesicles or in the presence of leupeptin, a gingipain inhibitor, during the treatment. Recombinant human CD14 receptors were found to be susceptible to proteolytic degradation by P. gingivalis vesicles. A purified Arg-gingipain preparation produced much more degradation than a Lys-gingipain preparation. This study provides evidence that P. gingivalis outer membrane vesicles contribute to the loss of membrane-bound CD14 receptors and that gingipains degrade this LPS receptor. Such a phenomenon, which results in an hyporesponsiveness of macrophages to LPS stimulation, may contribute to an increased capacity of P. gingivalis, and other periodontopathogens, to evade the host immune system mechanisms.  相似文献   
40.
Although estrogen is known to play a crucial role in the pathogenesis of breast cancer, the molecular mechanisms underlying the action of estrogen remain elusive. In the present study, we focused on keratinocyte growth factor (KGF) and its receptor (KGFR) in the pathogenesis of breast cancer, as a growth factor mediating estrogen action, since significant roles of KGF were demonstrated in various steroid hormone-dependent tissues. First, using paraffin-embedded specimens from 42 breast cancer patients, we examined expression patterns of KGF and KGFR by both immunohistochemistry using newly generated antibodies and nonradioactive in situ hybridization with T-T dimerized synthetic oligonucleotide probes. We next compared the results with the expression of estrogen receptor (ER) alpha and beta, proliferative activity and apoptotic frequency (TUNEL staining). Also, the similar approaches were taken to analyze the expression and role of KGF in ER-positive (MCF7, ZR-75-1) and ER-negative (SK-BR-3, MDA-MB-231) human breast cancer cell lines in vitro. In the surgical specimens, KGF was expressed in cancer cells as well as stromal cells in 19/42 cases (45%), while KGFR was found in cancer cells in 24/42 cases (57%). The distribution of protein and mRNA in the analysis of both KGF and KGFR expression generally coincided. Moreover, KGF expression was closely associated with the expression of ER alpha, and the coexpression of KGF and KGFR significantly correlated with lower TUNEL index, but not with proliferative activity. In accordance with the in vivo findings, KGF expression was detected only in ER alpha-positive MCF7 and ZR-75-1 cells in vitro. And more importantly, we found the inhibitory effect of KGF upon the induction of apoptosis by anticancer drugs in MCF7 cells. Collectively, our results indicate that ER alpha may be involved in KGF expression, and that KGF may play antiapoptotic roles, rather than mitogenic, in human breast cancer.  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