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   122179篇
  免费   7095篇
  国内免费   717篇
耳鼻咽喉   1304篇
儿科学   4061篇
妇产科学   2897篇
基础医学   17222篇
口腔科学   4158篇
临床医学   11269篇
内科学   27477篇
皮肤病学   3180篇
神经病学   11688篇
特种医学   2990篇
外国民族医学   1篇
外科学   11998篇
综合类   580篇
一般理论   68篇
预防医学   11663篇
眼科学   2055篇
药学   8414篇
中国医学   447篇
肿瘤学   8519篇
  2024年   135篇
  2023年   1145篇
  2022年   2427篇
  2021年   4221篇
  2020年   2619篇
  2019年   3513篇
  2018年   3996篇
  2017年   3026篇
  2016年   3511篇
  2015年   3831篇
  2014年   5037篇
  2013年   6591篇
  2012年   9961篇
  2011年   10343篇
  2010年   5632篇
  2009年   4795篇
  2008年   8194篇
  2007年   8281篇
  2006年   7593篇
  2005年   7093篇
  2004年   6399篇
  2003年   5669篇
  2002年   5082篇
  2001年   755篇
  2000年   570篇
  1999年   787篇
  1998年   922篇
  1997年   729篇
  1996年   622篇
  1995年   513篇
  1994年   497篇
  1993年   424篇
  1992年   403篇
  1991年   318篇
  1990年   302篇
  1989年   296篇
  1988年   276篇
  1987年   247篇
  1986年   271篇
  1985年   219篇
  1984年   234篇
  1983年   212篇
  1982年   237篇
  1981年   217篇
  1980年   193篇
  1979年   155篇
  1978年   150篇
  1977年   135篇
  1976年   103篇
  1974年   103篇
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
161.
Summary The present study demonstrates that the muscarinic antagonist atropine and the -adrenergic agonist clonidine, though ineffective when administered separately, produced a pronounced locomotor stimulation in monoamine-depleted mice when combined. The atropine + clonidine-induced locomotor stimulation was counteracted by both the 2-adrenoceptor antagonist idazoxan and the acetylcholinesterase inhibitor physostigmine. Thus, it is clear that simultaneous manipulations with cholinergic and adrenergic systems are as effective in restoring locomotion in monoamine-depleted mice as increasing central dopaminergic tone. This finding may have implications for the treatment of a movement disorder like Parkinson's disease.  相似文献   
162.
163.
In the course of a phase I trial, in which recombinant IL-2 (rIL-2) was infused intraperitoneally (i.p.) in patients with peritoneal carcinomatosis, we evaluated the effect on "tumor-associated lymphocytes" (TAL) isolated from the ascitic fluid. No major changes in the percentages of cells expressing the CD3, CD4, CD8, Leu-7, OKM1 and WT-31 antigens were detected either in TAL or in peripheral blood lymphocytes (PBL) after 7 days of rIL-2 infusion. In contrast the percentages of TAL (but not PBL) expressing surface IL-2 receptor (Tac), or LAK-1 antigen were sharply increased. Analysis of cytolytic functions showed a potentiation of the lytic activity against natural-killer (NK) sensitive K562 target cells and the de novo appearance of lytic activity against fresh melanoma cells. In one patient IFN-gamma was detected in the ascitic fluid following rIL-2 infusion. T-cell clones derived from the patient were analyzed for the IFN-gamma production. While only approximately 40% of PB-derived control clones produced medium to low amounts of IFN-gamma, all of the TAL-derived clones produced medium to high amounts of the lymphokine.  相似文献   
164.
The regulation of the immune responses by antibody administered passively on peritoneal exudate cells (PEC) was studied in guinea-pigs. The immunogenicity of sheep red blood cells (SRBC) associated with PEC for the induction of delayed hypersensitivity (DH) to soluble erythrocyte antigen was enhanced when PEC were incubated with anti-SRBC antibody. In contrast, the antibody response to SRBC was depressed. This phenomenon was only observed with specific antibody and was partially blocked when PEC covered with anti-SRBC antibody were incubated with rabbit anti-guinea-pig globulin serum. Comparable amounts of anti-SRBC antibody injected separately had no enhancing effect. Anti-SRBC sera from which the cytophilic antibody activity had been removed were inactive. PEC-associated SRBC were usually more immunogenic than the same amount of `free' SRBC for the induction of delayed hypersensitivity and always more immunogenic for antibody production.

These observations suggested that macrophage cytophilic antibody might be involved in the regulation of the immune response and play a role in the preferential induction of delayed hypersensitivity in the studied system.

  相似文献   
165.
The LightCycler polymerase chain reaction (PCR) is a sensitive assay for the detection of Herpes simplex virus (HSV) DNA in muco-cutaneous swabs. Software-based analysis of the probe melting temperature (Tm) can be used to discriminate between HSV types (HSV-1 and HSV-2). Among 76 HSV DNA positive genital swabs, atypical Tms were observed in 14 (18%). The 14 samples were all typed as HSV-2 by sequence alignment. In 4/14 samples, the atypical Tm was associated with sequence variation at the probe-binding site. Among 10 samples with conserved sequences, Tms were influenced by the specimen preparation method prior to PCR. These findings indicate that multiple factors including, but not limited to sequence variation complicate melting curve analysis following real-time PCR. Alternative typing methods are recommended for specimens with atypical melting curves.  相似文献   
166.
The objective of radiotherapeutic management in esophageal cancer is to accomplish maximum tumor sterilization with minimal normal tissue damage. This sincere effort is most often countered by the differential in tumor dose response vs normal tissue tolerance. Intraluminal isotope radiation, with its inherent advantage of rapid dose falloff, spares the lungs, the spinal cord, and other vital structures, yet yields adequately high doses to esophageal tumor. Though in existence since the turn of the century, the method of intracavitary radium bougie application dropped out of favor due to technical difficulties imposed by the size of the radium source and radiation exposure to the personnel involved. The authors describe a simple “iridium 192 afterloading intraluminal technique” that eliminates technical problems and reduces radiation exposure considerably.  相似文献   
167.
168.
Zusammenfassung Es wird über zwei beobachtete Fälle von akuter Myokarditis berichtet, welche im Verlaufe bzw. im Anschlusse an eine akute Infektionskrankheit auftraten, bei denen die elektrokardiographisch festgestellten Störungen des Rhythmus und des Erregungsablaufes für die Stellung der Diagnose von großem Werte waren. In beiden Fällen trat nach einer kurzen Krankheitsdauer völlige Erholung ein.  相似文献   
169.
Pain in individuals with RASopathies is a neglected topic in literature. In this article, we assessed prevalence and profile of pain in a sample of 80 individuals affected by RASopathies. The study sample included individuals with Noonan syndrome (N = 42), Costello syndrome (N = 17), and cardio‐facio‐cutaneous syndrome (N = 21). A set of standardized questionnaires and scales were administered (VAS/numeric scale, r‐FLACC, Wang‐Baker scale, NPSI, BPI, NCCPC‐R) to detect and characterize acute and chronic pain and to study the influence of pain on quality of life (PEDs‐QL, SF‐36) and sleeping patterns (SDSC); revision of past medical history and multisystemic evaluation was provided. Available clinical data were correlated to the presence of pain. High prevalence of acute (44%) and chronic (61%) pain was documented in the examined sample. Due to age and intellectual disability, acute pain was localized in 18/35 individuals and chronic pain in 33/49. Muscle‐skeletal and abdominal pain was more frequently reported. The intensity of acute and chronic pain interfered with daily activities in 1/3 of the sample. Pain negatively impacted on QoL and sleeping patterns. This work documents that pain is highly prevalent in RASopathies. Future studies including subjective and objective measures of pain are required to discriminate a somatosensory abnormality from an abnormal elaboration of painful stimuli at a central level.  相似文献   
170.
Gram-negative and gram-positive infections have been considered the most important causes of morbidity and mortality in patients with leukopenia following chemotherapy. However, discrimination between bacterial infections and harmless fever episodes is difficult. Because classical inflammatory signs of infection are often absent and fever is frequently the only sign of infection, the aim of this study was to assess the significance of serum interleukin-6 (IL-6), IL-10, macrophage inflammatory protein-2 (MIP-2), procalcitonin (PCT), and C-reactive protein (CRP) patterns in identifying bacterial infections during start of fever in normal and cyclophosphamide-treated (leukopenic) rats following an injection of lipopolysaccharide (LPS) or muramyl dipeptide (MDP) as a model for gram-negative and gram-positive bacterial infections. We found that, compared to normal rats, immunosuppressed animals exhibited significantly higher fevers and lesser production of all mediators, except IL-6, after toxin challenge. Moreover, compared to rats that received MDP, both groups of animals that received an equivalent dose of LPS showed significantly higher fevers and greater increase in serum cytokine levels. Furthermore, in contrast to those in immunocompetent rats, serum levels of IL-6 and MIP-2 were not significantly changed in leukopenic animals after MDP injection. Other serum markers such as PCT and CRP failed to discriminate between bacterial stimuli in both groups of animals. These results suggest that the use of the analyzed serum markers at an early stage of fever could give useful information for the clinician for excluding gram-negative from gram-positive infections.  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