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   1114篇
  免费   187篇
  国内免费   2篇
耳鼻咽喉   5篇
儿科学   15篇
妇产科学   16篇
基础医学   277篇
口腔科学   5篇
临床医学   124篇
内科学   330篇
皮肤病学   42篇
神经病学   66篇
特种医学   33篇
外科学   164篇
综合类   4篇
一般理论   1篇
预防医学   43篇
眼科学   12篇
药学   44篇
中国医学   1篇
肿瘤学   121篇
  2023年   10篇
  2022年   10篇
  2021年   30篇
  2020年   18篇
  2019年   19篇
  2018年   25篇
  2017年   18篇
  2016年   18篇
  2015年   21篇
  2014年   41篇
  2013年   33篇
  2012年   62篇
  2011年   52篇
  2010年   31篇
  2009年   27篇
  2008年   45篇
  2007年   43篇
  2006年   49篇
  2005年   39篇
  2004年   53篇
  2003年   51篇
  2002年   43篇
  2001年   33篇
  2000年   33篇
  1999年   35篇
  1998年   13篇
  1997年   19篇
  1996年   13篇
  1995年   12篇
  1994年   10篇
  1992年   19篇
  1991年   13篇
  1990年   27篇
  1989年   37篇
  1988年   23篇
  1987年   22篇
  1986年   27篇
  1985年   14篇
  1984年   12篇
  1983年   16篇
  1979年   10篇
  1978年   18篇
  1977年   14篇
  1976年   15篇
  1975年   18篇
  1972年   10篇
  1970年   8篇
  1968年   10篇
  1967年   8篇
  1966年   8篇
排序方式: 共有1303条查询结果,搜索用时 31 毫秒
81.
82.
Zusammenfassung Bei 100 psychiatrischen Patienten wurde in der poliklinischen Sprechstunde eine Diagnose gestellt und die erhobenen Daten in die anamnestiscen und Befundbögen der CAPPS (Current and Past Psychopathology Scales) von Spitzer und Endicott eingetragen. Das Computerprogramm DIAL — eine Modifikation des DIAGNO II-Programms derselben Autoren — und zwei Kliniker stellten unabhängig davon und nur auf Grund der Angaben in den CAPPS-Bögen ebenfalls eine Diagnose für die gleichen Patienten. Die Übereinstimmung zwischen diesen verschiedenen Diagnosen wurde geprüft und die Ergebnisse mit früheren ähnlichen Untersuchungen von Schmid et al. verglichen, bei denen jedoch die CAPPS unter Verwendung der Krankengeschichte und nicht auf Grund direkter ambulanter Untersuchung ausgefüllt worden waren. Diese Modifikation der Datenerhebung erbrachte eine leichte, aber statistisch nicht signifikante Verbesserung in der Diagnostiker-Übereinstimmung. Die Möglichkeit, durch Verwendung einer anderen Skala die diagnostische Übereinstimmung zwischen ambulanter, Computer- und Fragebogendiagnostik zu erhöhen, wird diskutiert.Die Autoren danken Herrn Professor Dr. med. D. v. Zerssen und Herrn Dipl. Math. P. O. Degens für Ratschläge und Hilfe bei der Abfassung der Arbeit.  相似文献   
83.
A randomised double-blind investigation was undertaken to assess the value of domperidone and metoclopramide as prophylactic anti-emetics in unpremedicated patients undergoing general anaesthesia for therapeutic abortion on a day care basis. Sixty patients were divided into three groups, and received, at induction, one of three drugs intravenously. The incidences of postoperative nausea and vomiting were 35% in the group receiving normal saline as placebo, 30% in the group receiving 10 mg domperidone and 25% in the group receiving 10 mg metoclopramide; these were not statistically significantly different. Furthermore, there was no statistically significant difference in the incidence of postoperative nausea and vomiting as influenced by age, weight, length of gestation, anaesthetic time and a history of nausea and vomiting during the pregnancy.  相似文献   
84.
Characterization of the human receptor for T-cell growth factor.   总被引:25,自引:8,他引:17       下载免费PDF全文
Anti-Tac monoclonal antibody has been identified as a putative antibody against the receptor for T-cell growth factor (TCGF). We now show that: (i) TCGF blocks 85% of 3H-labeled anti-Tac binding to phytohemagglutinin-activated lymphoblasts and (ii) both anti-Tac and anti-TCGF immunoprecipitate a protein band that appears to represent TCGF crosslinked to its receptor on HUT-102B2 cells. In HUT-102B2 cells, the TCGF receptor is a Mr 50,000 glycoprotein with internal disulfide bond(s) and a pI of 5.5-6.0, and it represents approximately equal to 0.05% of total cellular de novo protein synthesis. It contains a peptide of Mr 33,000 that is processed to a mature form that includes N-linked and O-linked sugars and sialic acid.  相似文献   
85.
Limiting dilution analysis of helper T-cell function.   总被引:11,自引:5,他引:6       下载免费PDF全文
H Waldmann  I Lefkovits    J Quintns 《Immunology》1975,28(6):1135-1148
Limiting dilution analysis has been applied to the study of T-cell 'helper' function in vitro. Using the microculture system one can estimate the numbers of (a) 'helper' T cells involved in specific collaboration with B cells and (b) those T cells which are able, on being activated by their specific antigen, to facilitate the response of B cells to another antigen. Such studies have enabled us to demonstrate that: (1) a single 'helper' T cell was able to activate a single B-cell precursor to detectable antibody production; (2) the 'helper' function of primed T cells was radio-resistant; (3) a minimal estimate of 'helper' frequencies could be obtained in defined cell populations; (4) nonspecific facilitation was directed towards virtually all available B cells of a given specificity if these were challenged with their appropriate particulate antigen; (5) the microculture system offers the opportunity to determine whether specific and non-specific T-cell 'helper' effects are a consequence of the activity of one T-cell type or of differenct subpopulations of T cells.  相似文献   
86.
The occurrence of granular cell tumor (GCT) in penile tissue is very rare, with only 9 examples reported to date in the English-language literature. Herein, we describe the clinicopathologic and immunohistochemical findings in 9 additional cases. The patients ranged in age from 20 to 60 years (mean, 42 years; median, 40 years) at time of diagnosis. All penile tumors were solitary and arose in the dermis of the penile shaft (n=4), prepuce (n=3), and corona (n=2). A patient had a history of multiple cutaneous GCTs. Duration of symptoms before surgery ranged from 5 days to 2 years with the presence of an asymptomatic nodule representing the most common tumor-related complaint (n=8). The lesions ranged in size from 0.6 to 2.5 cm (mean, 1.5 cm; median, 1.5 cm). Microscopically, the tumors were moderate to highly cellular and were composed of oval to polygonal-shaped cells with abundant coarsely granular eosinophilic cytoplasm. Tumor cells grew in infiltrating nests, cords, and trabeculae and showed neural (n=2) and vessel wall (n=1) invasion or formed a relatively well-marginated solid nodule. Bland cytological features with only rare cells showing nucleomegaly (n=7) or spindling (n=3) were exhibited by 8 tumors. A tumor demonstrated diffuse nuclear atypia and was classified as "atypical." Mitotic activity ranged from 0 to 8 mitoses (mean, 1.4 mitoses) per 50 high-powered fields with no atypical division figures identified. All tumors tested showed moderate to strong immunohistochemical expression of S100 protein (n=6) and low-affinity nerve growth factor receptor (n=5), which was useful for detecting small deposits of tumor and helpful in evaluating surgical margins. Focal tumor cell immunoreactivity was observed for calretinin (4/6 cases) and glial fibrillary acidic protein (1/6 cases). All patients underwent simple (local) excision of their tumor. Complete follow-up data (mean, 21 years; interval range, 0.5-28 years) were available for 6 patients. No patient experienced recurrence or metastatic spread of tumor although surgical margins were microscopically involved by tumor in 5 cases. Benign GCT involving superficial soft tissue of the penis can be adequately managed by a simple excision. Patients with microscopically involved surgical margins can be clinically followed without immediate additional surgery.  相似文献   
87.
Epithelioid hemangiomas of the penis are very rare. To date, less than 10 examples have been reported in the English language literature. In this report, we describe the clinical, histopathologic, and immunohistochemical findings in 19 cases retrieved from our files. The patients ranged in age from 23 to 75 years (median age, 45 years) at the time of initial surgical resection. Seventeen patients presented with a solitary mass, and two presented with two separate, but closely approximated, lesions. The process involved the glans penis (n = 3), shaft (n = 11), base of the penis (n = 2), or penis, not otherwise specified (n = 3). The lesions ranged in size from <0.5 to 2.5 cm (median size, approximately 1.2 cm) in greatest dimension. Eleven examples were specifically noted to be dorsally located, and only one was stated to be ventral. Localized pain or tenderness was the most common complaint, documented in 12 cases. The preoperative duration of the lesions ranged from 5 days to 1 year (median 4.5 months). Microscopically, all examples contained a tumefactive proliferation of epithelioid endothelial cells, often in a nodular or lobular configuration and associated with an inflammatory infiltrate containing lymphocytes and eosinophils. In 14 cases, the vascular proliferation was associated with a small arterial segment, sometimes with mural damage and frequently (n = 13) with intraluminal epithelioid endothelial cells. Based on the growth pattern of the epithelioid endothelial cells, 13 cases were considered "typical," and six were considered exuberant or "atypical." The latter examples had a prominent centrally located zone where nests or sheet-like aggregates of epithelioid endothelial cells did not form discrete vessels. Immunohistochemical data are available for 15 tumors. The epithelioid endothelial cells usually had strong reactivity for CD31, lesser reactivity for factor VIIIrAg, and minimal reactivity for CD34. In 9 of 12 cases, a small number of epithelioid endothelial cells expressed keratins. In all cases tested, at least focal muscle-specific actin-positive myopericytic cells were present bordering the endothelial cells, and this was especially notable peripherally. Initial surgical intervention consisted of either a shave biopsy (n = 1), excisional biopsy (n = 2), or local excision (n = 16). A complete follow-up history is available for 12 patients, and incomplete follow-up information is available for an additional four patients. One patient developed a new epithelioid hemangioma at a site within the penis separate from the initial lesion, but no patient is known to have experienced a true metastasis or to have died of complications of this process. Optimal management appears to be complete local excision with periodic follow-up visits to monitor for local recurrence.  相似文献   
88.
The syntheses, radiolabeling, antibody conjugation and in vivo evaluation of new linkers for (211)At labeling of monoclonal antibodies are described. Syntheses of the N-succinimidyl esters and labeling with (211)At to form succinimidyl 4-methoxymethyl-3-[(211)At]astatobenzoate (9) and succinimidyl 4-methylthiomethyl-3-[(211)At]astatobenzoate (11) from the corresponding bromo-aryl esters is reported. Previously reported succinimidyl N-{4-[(211)At]astatophenethyl}succinamate (SAPS) is employed as a standard of in vivo stability. Each agent is conjugated with Herceptin in parallel with their respective (125)I analogue, succinimidyl 4-methoxymethyl-3-[(125)I]iodobenzoate (10), succinimidyl 4-methylthiomethyl-3-[(125)I]iodobenzoate (12) and succinimidyl N-{4-[(125)I]iodophenethyl}succinamate (SIPS), respectively, for comparative assessment in LS-174T xenograft-bearing mice. With 9 and 11, inclusion of an electron pair donor in the ortho position does not appear to provide in vivo stability comparable to SAPS. Variables in radiolabeling chemistry of these three agents with (211)At are notable. Sequential elimination of acetic acid and oxidizing agent, N-chlorosuccinimide (NCS), from the (211)At radiolabeling protocol for forming SAPS improves yield, product purity and consistency. NCS appears to be critical for the radiolabeling of 6 with (211)At. Formation of 11, however, is found to require the absence of NCS. Elimination of acetic acid is found to have no effect on radiolabeling efficiency or yield for either of these reactions.  相似文献   
89.
Regulatory T cells and organ transplantation   总被引:13,自引:0,他引:13  
Empirical studies attempting to explain tolerance to transplanted tissues have demonstrated a regulatory role for CD4+ T-cells. We here propose that regulatory T-cells mediating transplantion tolerance comprise two sets which can functionally complement each other. The CD4+CD25+ "natural regulator" arises in the thymus, and is preoccupied with self-antigens expressed at sites of inflammation. The second, comprising both CD4+CD25+ (FoxP3+) and CD4+CD25- Tr1-like cells are induced by persistent danger-free antigen in the periphery. The role of these cells is to moderate immune responses to prevent tissue destruction while allowing microbial elimination.  相似文献   
90.
Repetitive movements have been reported to induce task-specific changes of intracortical inhibition and facilitation, but the mechanism operating shortly after hand movement is unclear. Transcranial magnetic single and paired stimuli (2 ms) were applied to 15 healthy subjects at rest and 1 s after repetitive (every 6 s) active and passive hand extensions. Motor evoked potentials (MEPs) were recorded from hand extensors (agonists) and flexors (antagonists). A strong overall inhibitory effect was observed after applying paired stimuli. In agonists only, active movements produced significantly larger MEPs. Inhibition, however, did not differ between active or passive movements and rest. This suggests that MEP increases produced by active movements in agonists are not caused by disinhibition, but are rather due to excitation (facilitation). This finding may also have implications for future studies evaluating the preferential activation of target muscles in physiotherapy.  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