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   447篇
  免费   25篇
耳鼻咽喉   5篇
儿科学   2篇
妇产科学   43篇
基础医学   46篇
口腔科学   9篇
临床医学   21篇
内科学   69篇
神经病学   46篇
特种医学   11篇
外科学   38篇
预防医学   32篇
眼科学   3篇
药学   81篇
肿瘤学   66篇
  2021年   5篇
  2019年   4篇
  2018年   5篇
  2017年   9篇
  2016年   9篇
  2013年   8篇
  2012年   17篇
  2011年   14篇
  2010年   8篇
  2009年   11篇
  2008年   10篇
  2007年   17篇
  2006年   11篇
  2005年   14篇
  2004年   10篇
  2003年   6篇
  2002年   7篇
  2001年   22篇
  2000年   21篇
  1999年   19篇
  1997年   8篇
  1996年   4篇
  1995年   5篇
  1994年   5篇
  1993年   7篇
  1992年   18篇
  1991年   21篇
  1990年   10篇
  1989年   12篇
  1988年   10篇
  1987年   14篇
  1986年   6篇
  1985年   14篇
  1984年   9篇
  1983年   9篇
  1981年   4篇
  1980年   5篇
  1979年   15篇
  1978年   5篇
  1977年   9篇
  1976年   6篇
  1974年   6篇
  1973年   4篇
  1972年   3篇
  1971年   4篇
  1969年   3篇
  1968年   3篇
  1967年   3篇
  1966年   3篇
  1965年   3篇
排序方式: 共有472条查询结果,搜索用时 15 毫秒
1.
2.
uPAR (CD87), the receptor for the urokinase-type plasminogen activator (uPA) facilitates tumor cell invasion and metastasis by focusing uPA proteolytic activity to the cell surface. As uPAR exists in various molecular forms, it is desirable to use well defined antibodies for analyses of uPAR antigen expression in human malignant tumors by immunological methods. Therefore, twelve monoclonal antibodies (MAbs) directed against uPAR were generated by using nonglycosylated, recombinant human uPAR (spanning amino acids 1 to 284), expressed in Escherichia coli, as the immunogen. The reaction pattern of these MAbs with the immunogen and a series of carboxyl-terminally truncated versions of uPAR demonstrated that at least six different epitopes of uPAR are recognized. All MAbs reacted under reducing conditions in immunoblot analyses with E. coli-expressed uPA and also with highly glycosylated, functionally intact, recombinant human uPAR expressed in Chinese hamster ovary (CHO) cells. Seven of the MAbs recognized CHO uPAR under nonreducing conditions as well. By flow cytofluorometric analyses, three of these MAbs were shown to bind to native human uPAR present on the cell surface of monocytoid U937 cells with MAb IIIF10 being the best. Saturation of uPAR with uPA on U937 cells completely blocked interaction of MAb IIIF10 with uPAR (mapped epitope, amino acids 52 to 60 of domain I of uPAR). In turn, preincubation of U937 cells with MAb IIIF10 efficiently reduced binding of uPA to uPAR, indicating that the epitope detected by MAb IIIF10 is located within or closely to the uPA-binding site of uPAR, and thus, this site may be a target to influence uPA/uPAR-mediated proteolysis in tumors. Binding of MAbs IID7 or IIIB11 (mapped epitope, amino acids 125 to 132 of domain II of uPAR) to uPAR is not affected when uPAR is occupied by uPA. As these MAbs reacted strongly with cellular uPAR antigen in formalin-fixed paraffin-embedded tumor sections, the domain-II-specific antibodies IID7 and IIIB11 may be useful for immunohistochemical studies of uPAR expression in tissue remodeling processes in tumor invasion. In conclusion, we have devised well defined and epitope-mapped MAbs to uPAR that are highly specific tools for detection and targeting of uPAR in tumor tissue.  相似文献   
3.
To study the role of natural killer cells and immunoregulatory T cells in the pathogenesis of proctitis due to Chlamydia trachomatis (L2 serovar), lymphocytes were obtained from the rectal mucosa and other sites of nonhuman primates and studied by using phenotypic and functional assays. In animals with lymphogranuloma venereum (LGV) proctitis, the percentage of lymphocytes with the natural killer cell phenotype (Leu-11+) was not significantly higher at any site in LGV infection, and natural killer cell function of lymphocytes isolated from the rectum was lower during LGV infection. This was not due to the suppressive effect of factors in serum, rectal lymphocytes, or LGV elementary bodies. In studies of regulatory T cells, the Leu-3+/Leu-2+ ratio was lower in the peripheral blood and the spleen during LGV infection, but the ratio did not decrease in lamina propria T cells. Both peripheral blood and rectal lymphocytes had higher helper T-cell function for polyclonal immunoglobulin G (IgG) synthesis in pokeweed mitogen-stimulated cultures 2 weeks following LGV infection. Increased suppressor T-cell function for pokeweed mitogen-stimulated IgG synthesis was found only in the peripheral blood of animals 2 weeks after infection, but not in isolated rectal lymphocytes. These results indicate that in LGV proctitis natural killer cells are not an important component of the inflammatory infiltrate at the site of infection, and helper T-cell function increases in peripheral blood and rectal lymphocytes.  相似文献   
4.
Circulating immune complexes after a test meal were measured with three methods (PEG precipitation, Clq-ELISA and the indirect granulocyte phagocytosis test) in 10 controls, two symptomless persons with selective IgA deficiency and 14 patients with various types of glomerulonephritis, of which two patients (with idiopathic membranous glomerulopathy and local focal glomerulonephritis) also had selective IgA deficiency. The PEG and Clq-ELISA test did not show significant differences between the groups. In the two symptomless persons with selective IgA deficiency and in the patient with local focal glomerulonephritis and selective IgA deficiency the indirect granulocyte phagocytosis test (IGFT) showed a reproducible increase in IgG, IgM and complement containing immune complexes. In the last patient multiple food antigens were probably responsible for this phenomenon, a rapid amelioration of kidney function could be induced three times by giving an antigen free diet.  相似文献   
5.
In order to assess the role played by serotonin (5-HT) and noradrenaline in anxiety, four groups of healthy volunteers were given 25 mg of the selective inhibitor of 5-HT uptake chlorimipramine, 50 mg of the selective inhibitor of noradrenaline uptake maprotiline, 1 mg of the benzodiazepine anxiolytic lorazepam or placebo, and submitted to a simulated public speaking (SPS) test, consisting of speaking in front of a videocamera. Subjective anxiety was evaluated by the visual analog mood scale (VAMS) of Norris as well as by the state-trait anxiety inventory (STAI) of Spielberger. Chlorimipramine enhanced SPS-induced anxiety, whereas maprotiline and lorazepam reduced anxiety during as well as outside the test period. Mental and physical sedation (VAMS) were increased by either maprotiline or lorazepam. In a scale of bodily symptoms, chlorimipramine tended to increase muscle tension, agitation and palpitation, whereas maprotiline caused lethargy. The rise in blood pressure induced by the SPS procedure outlasted the period of stress in the group treated with chlorimipramine. In contrast, the SPS-induced increase in heart rate was enhanced by lorazepam. Chlor imipramine and maprotiline reduced salivation to the same extent. Pupillary diameter, however, was significantly increased by chlorimipramine alone. It may be tentatively sug gested that the proanxiogenic effect of chlorimipramine is related to changes in central 5-HT neurotransmission while the anxiolytic effect of maprotiline is associated with alteration of noradrenergic mechanisms. Increased peripheral sympathetic tone may also contribute to the proanxiety action of chlorimipramine.  相似文献   
6.
Flow cytometric analysis of tumor cells in carcinomas is hampered by the presence of a variety of different cells in the tumor tissue and the surrounding stroma. To obtain single competent tumor cells, we have established a model system which can be applied to separate living cells from fresh ovarian carcinoma tissue. Due to the lack of tumor-cell surface specific antibodies, we isolated tumor cells by a procedure called 'negative tumor cell selection'. For this purpose, fresh ovarian carcinoma tissue, immediately after surgery, was subjected to mechanical disintegration using an automated mincing device to obtain a single-cell suspension (approximately 10(7) cells/g). Collagenase D (0.005%) was added to prevent further aggregation. Cells other than tumor cells were then labeled with a set of monoclonal antibodies directed to cell surface antigens: CD3 (T-cells), CD14 (monocytes), CD15 (granulocytes), CD45R (T-/B-cells) and 5B5 (fibroblasts). Anti-isotype antibodies coupled to ferrit microbeads were then reacted with the cell suspension and those cells reacting with the microbeads retained on a steel wool matrix in a magnetic field (1). Tumor cells not reacting with the microbeads were recovered by a simple wash of the steel wool matrix. All incubation steps were at 4 degrees C. This procedure, which takes about 2 hours, enables fast and simple isolation of single, living competent tumor cells from fresh tumor tissue and also from ascitic or pleuritic effusions. In a model system with cultured ovarian carcinoma cells and human leukocytes, tumor cell purity was about 93% and about 97% when re-subjected to the same procedure (respective recovery rates 75% and 50%). The still unlabeled tumor cells can subsequently be analyzed by flow cytometry or by central laser scanning microscopy for the presence of various surface antigens including receptors for proteases or growth factors. Moreover, after detergent treatment and fixation, flow cytometric multiparameter analysis such as simultaneous labeling of intracellular and surface antigens as well as nuclear DNA staining for ploidy and S-phase determination becomes possible.  相似文献   
7.
The dose-effect relationships of intraventricularly injected bradykinin, angiotensin II, and substance P on lever-lifting behavior of rabbits in a multiple fixed-interval 2-min, fixed-ratio 15 responses (mult. FI 2 FR 15) schedule of sweetened water presentation were determined. Bradykinin, in doses of 30 and 56 ng, increased FI response rates, with lower rates being relatively more increased than higher rates while FR responding was not affected. Conversely, 3 ng of angiotensin II increased only FR response rates. Higher doses of both peptides, up to 1.7 and 1.0 g, respectively, caused dose-dependent decreases in both FI and FR response rates, mainly as a consequence of complete response supression at the beginning of the experimental session. Doses of 0.1, 0.3, and 1.0 g of substance P caused dosedependent decreases in FI and FR response rates with no initial pause, FI response rates being more affected than FR rates. But 3.0 g of substance P caused an initial response suppression as well as comparable decreases in both FI and FR rates. Combined treatments of bradykinin with selected doses of amphetamine, haloperidol, atropine, morphine, and naloxone caused effects on multiple FI FR performance that did not consistently differ from the effect of bradykinin alone. These results show that small amounts of bradykinin, angiotensin II, and substance P cause specific and selective effects on operant behavior when injected into the cerebral ventricles, indicating that these endogenous peptides may play functional roles in behavioral regulation.  相似文献   
8.
Several randomized studies and meta‐analyses have shown that simultaneous radio‐ and chemotherapy prolongs survival in patients with unresectable squamous cell carcinoma of the head and neck as compared with conventional radiotherapy. We assessed the feasibility and effectiveness of simultaneous radiotherapy (35 × 2 Gy) and chemotherapy [cisplatinum 100 mg/m2 or carboplatin (AUC 6) on days 1, 22 and 43] in daily clinical practice in a cohort of 87 patients treated at our institute between 1998 and 2002. Eighty patients completed radiotherapy according to schedule. Eighty patients received two courses of chemotherapy and 50 patients three courses. Nephrotoxity, bone marrow suppression and ototoxicity were the most frequent side‐effects. Median weight loss was 8.5%. Median survival was 15 months and 44% of the patients were alive at 2 years. Patients receiving three courses of chemotherapy had a better survival than patients receiving two or less courses. Treatment with simultaneous radio‐ and chemotherapy for advanced head and neck cancer is a demanding, but feasible treatment in daily clinical practice. Survival seems to be comparable with the results achieved in patients selected for clinical trials.  相似文献   
9.
10.
A case of the nephrotic syndrome with unilateral renal vein thrombosis is reported. The patient, an 18 year old man, presented with a six month history of edema and the recent development of a left-sided varicocele. An enlarged left kidney and a thrombus in the left renal vein were demonstrated roentgenographically. A biopsy specimen of the right kidney was interpreted as membranous glomerulonephritis. Selective renal function studies showed nearly identical creatinine excretion, and similar total protein excretion and protein selectivity from each kidney. Thus, the thrombus in the left renal vein did not influence glomerular filtration rate or quantitative or qualitative protein excretion. A high urinary output and a decreased serum level of antithrombin III were measured. These findings suggest a mechanism to explain the increased thrombotic tendency seen in this and other patients with the nephrotic syndrome.  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