全文获取类型
收费全文 | 57368篇 |
免费 | 4629篇 |
国内免费 | 179篇 |
专业分类
耳鼻咽喉 | 642篇 |
儿科学 | 1852篇 |
妇产科学 | 1074篇 |
基础医学 | 7344篇 |
口腔科学 | 790篇 |
临床医学 | 6177篇 |
内科学 | 12298篇 |
皮肤病学 | 886篇 |
神经病学 | 5205篇 |
特种医学 | 2173篇 |
外国民族医学 | 3篇 |
外科学 | 9176篇 |
综合类 | 717篇 |
一般理论 | 92篇 |
预防医学 | 4983篇 |
眼科学 | 1514篇 |
药学 | 3422篇 |
中国医学 | 51篇 |
肿瘤学 | 3777篇 |
出版年
2023年 | 459篇 |
2022年 | 777篇 |
2021年 | 1751篇 |
2020年 | 907篇 |
2019年 | 1513篇 |
2018年 | 1795篇 |
2017年 | 1264篇 |
2016年 | 1388篇 |
2015年 | 1483篇 |
2014年 | 2080篇 |
2013年 | 2561篇 |
2012年 | 4146篇 |
2011年 | 4213篇 |
2010年 | 2336篇 |
2009年 | 2056篇 |
2008年 | 3440篇 |
2007年 | 3411篇 |
2006年 | 3253篇 |
2005年 | 3148篇 |
2004年 | 3075篇 |
2003年 | 2681篇 |
2002年 | 2434篇 |
2001年 | 772篇 |
2000年 | 716篇 |
1999年 | 691篇 |
1998年 | 549篇 |
1997年 | 472篇 |
1996年 | 379篇 |
1995年 | 385篇 |
1994年 | 308篇 |
1993年 | 304篇 |
1992年 | 513篇 |
1991年 | 507篇 |
1990年 | 486篇 |
1989年 | 417篇 |
1988年 | 422篇 |
1987年 | 420篇 |
1986年 | 375篇 |
1985年 | 350篇 |
1984年 | 331篇 |
1983年 | 297篇 |
1982年 | 225篇 |
1981年 | 186篇 |
1980年 | 170篇 |
1979年 | 243篇 |
1978年 | 203篇 |
1977年 | 175篇 |
1976年 | 170篇 |
1974年 | 167篇 |
1973年 | 195篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
32.
Rosario B Hidalgo Jerilyn Ross Jonathan R T Davidson 《Annals of clinical psychiatry》2006,18(3):157-162
BACKGROUND: Obsessive-compulsive disorder (OCD) is a chronic, impairing and often comorbid disorder. METHODS: 1000 subjects who called the Anxiety Disorders Association of America (ADAA) were surveyed and divided in three groups: (a) callers with OCD (OCD) and two overlapping control groups: (b) callers with no axis I disorder (NAC) and (c) with no-OCD (NOC) using a 97-item questionnaire. RESULTS: The rate of OCD was 14.5% (N = 145). Relative to the NOC group, OCD subjects were more likely to be female, White, younger and not married. Relative to the NAC group, subjects with OCD were more likely to be White, not married and younger. OCD was accompanied by significant comorbidity and was associated with an increased number of visits to health professionals than NAC subjects. There was no significant difference regarding unemployment rates among the three groups. However, OCD callers were more likely than both control groups to have missed work or have decreased productivity due to their mental condition. OCD subjects took an average of 1 psychotropic medication in the past year and were statistically more likely than the control groups to experience sleepiness and nervousness as side effects. CONCLUSIONS: OCD was fairly prevalent among ADAA callers and presented high levels of comorbidity, impairment, health care utilization and sensitivity to psychotropic side effects. 相似文献
33.
Avninder Dhaliwal Adrienne L West Jonathan D Trobe David C Musch 《Journal of neuro-ophthalmology》2006,26(1):4-10
BACKGROUND: The relationship between the circumstances and severity of closed head injury (CHI) and the clinical and imaging features of cranial nerve 3, 4, and 6 palsies has not been rigorously addressed in a large study. METHODS: Retrospective chart review of 210 consecutive patients with CHI examined at a single tertiary care center from 1987 to 2002. Patients were located by searching the ophthalmology inpatient consultation and neuro-ophthalmology outpatient databases and hospital emergency room billing codes for a diagnosis of traumatic 3, 4, or 6 cranial nerve palsy (Cranial Nerve Injury Group) and a diagnosis of CHI without traumatic 3, 4, or 6 nerve palsy (Control Group). The Cranial Nerve Injury Group was then subdivided into two groups: those with injuries to an individual cranial nerve and those with multiple (including bilateral) cranial nerve injuries. Comparisons between groups were based on age, gender, type of accident, Glasgow Coma Scale (GCS), documented loss of consciousness (LOC), type of ocular injury, presence of systemic injury, need for rehabilitation, physical therapy and cognitive scores, and imaging features. RESULTS: The Cranial Nerve Injury Group had a significantly higher severity of head injury, more CT abnormalities, and worse short-term neurologic outcomes as compared with the Control Group. These trends were also found when each cranial nerve injury subgroup was compared with the Control Group. Those with cranial nerve 3 palsy had the most severe head injury; those with cranial nerve 4 palsy had an intermediate level of head injury; and those with cranial nerve 6 palsy had the lowest level of head injury. There were no consistent associations between the location of the imaging abnormalities and which cranial nerve was damaged. CONCLUSIONS: CHI with palsy of an ocular motor nerve was more severe than CHI without ocular motor nerve palsy, as measured by the GCS, intracranial and skull imaging abnormalities, and a greater frequency of inpatient rehabilitation. Palsy of cranial nerve 3 was associated with relatively more severe CHI than was palsy of cranial nerves 4 or 6. The location of the imaging abnormalities did not correlate with a particular cranial nerve injury. 相似文献
34.
Jonathan Larkin Anne Bost John I Glass Seng-Lai Tan 《Journal of interferon & cytokine research》2006,26(12):854-865
Hepatitis C virus (HCV)-specific impairments in host immunity have been described at multiple levels of the innate and adaptive response, which may lead to viral persistence in the majority of infections. Understanding of HCV-associated immune defects could lead to novel therapeutic advances. Natural killer (NK) cells, the major effector cells of the innate immune system, are functionally impaired in chronic HCV infection. It has been suggested that this phenotype is a result of virus-specific defects in antigen-presenting cells (APCs) that regulate NK cell activity, as normal NK function is restored when they are stimulated ex vivo. In this study, we used human NK cell cytotoxicity assays to evaluate the activation-induced effects of NK cells on the HCV replicon-containing hepatic cells. We found that cytokine-activated NK cells were capable of inducing an HCV-associated, perforin/granzyme-dependent lysis of human hepatoma cells and that this required direct cellular contact and was independent of MHC class I expression levels. In contrast, on removal of cytokine stimulation, NK cells failed to exert any direct cytolytic effect on replicon targets. These findings suggest an important underlying mechanism by which NK cells control HCV infection and, with appropriate understanding of HCV-associated immune defects, could lead to novel therapeutic advances. 相似文献
35.
36.
Evolution of the sperm aster after microinjection of isolated human sperm centrosomes into meiotically mature human oocytes 总被引:3,自引:2,他引:1
This study examined the feasibility of isolating and transferringthe centrosome-containing region of spermatozoa to mature humanoocytes. The findings demonstrate that individual sperm centrosomescan be transferred and are capable of nucleating maternal tubulinto form a well-developed sperm aster in the recipient oocyte.The results are discussed with respect to centrosome functionin early human development and applications in clinical in-vitrofertilization in the treatment of certain forms of male factorinfertility. 相似文献
37.
Gordon J. Harris Ph.D. Instructor Jonathan M. Links Ph.D. Associate Professor Godfrey D. Pearlson M.B. B.S. Director Edwaldo E. Camargo M.D. Associate Professor 《Psychiatry research》1991,40(3):167-180
We developed a semiautomatic method termed “cortical circumferential profiling” for objective analysis of cerebral cortex function in emission tomographic neuroimaging studies. This method treats cortex as a continuous ring near the outer brain edge. A computer algorithm samples the cortex at 60 contiguous, equiangular locations, using 1-cm2 samples. These values are plotted as a function of cortical angle to produce the cortical circumferential profile. This method was used in a study of regional cerebral perfusion in 15 patients with Alzheimer's disease and 8 elderly control subjects using N-isopropyl [I-123]-iodoamphetamine. Cortical circumferential profiling decreases variability, examines the entire cortex within slices at preselected levels above the orbital-meatal line, and facilitates intrasubject and intersubject comparisons. 相似文献
38.
39.
J W Rose H Lorberboum-Galski D Fitzgerald R McCarron K E Hill J J Townsend I Pastan 《Journal of neuroimmunology》1991,32(3):209-217
IL2-PE40 is a chimeric protein composed of human interleukin-2 (IL2) genetically fused to a modified form of Pseudomonas exotoxin lacking the cell recognition domain. IL2-PE40 is cytotoxic for IL2 receptor-bearing lymphocytes in culture and can inhibit activation of T cells in vivo. IL2-PE40 can significantly diminish antigen-stimulated proliferation of lymphocytes sensitized to myelin basic protein. Intraperitoneal administration of IL2-PE40 not only markedly inhibits the clinical manifestations of adoptively transferred relapsing experimental allergic encephalomyelitis but also dramatically reduces both inflammation and demyelination characteristic of the disease. 相似文献
40.
Sarcoplasmic reticulum calcium load regulates rat arterial smooth muscle calcium sparks and transient KCa currents 总被引:1,自引:1,他引:0
Voltage-gated Na+ current is reduced by acid solution. Protons reduce peak Na+ conductance by lowering single channel conductance and shift the voltage range of gating by neutralizing surface charges. Structure-function studies identify six carboxyls and a lysine in the channel's outer vestibule. We examined the roles of the superficial ring of carboxyls in acid block of Nav 1.4 (the rat skeletal muscle Na+ channel isoform) by measuring the effects of their neutralization or their substitution by lysine on sensitivity to acid solutions, using the two-micropipette voltage clamp in Xenopus oocytes. Alteration of the outer ring of carboxylates had little effect on the voltage for half-activation of Na+ current, as if they are distant from the channels' voltage sensors. The mutations did not abolish proton block; rather, they all shifted the p K a (-log of the dissociation constant) in the acid direction. Effects of neutralization on p K a were not identical for different mutations, with E758Q > D1241A > D1532N > E403Q. E758K showed double the effect of E758Q, and the other lysine mutations all produced larger effects than the neutralizing mutations. Calculation of the electrostatic potential produced by these carboxylates using a pore model showed that the p K a values of carboxylates of Glu-403, Glu-758, and Asp-1532 are shifted to values similar to the experimentally measured p K a . Calculations also predict the experimentally observed changes in p K a that result from mutational neutralization or introduction of a positive charge. We propose that proton block results from partial protonation of these outer ring carboxylates and that all of the carboxylates contribute to a composite Na+ site. 相似文献