全文获取类型
收费全文 | 2539篇 |
免费 | 146篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 154篇 |
儿科学 | 55篇 |
妇产科学 | 21篇 |
基础医学 | 312篇 |
口腔科学 | 41篇 |
临床医学 | 365篇 |
内科学 | 370篇 |
皮肤病学 | 27篇 |
神经病学 | 219篇 |
特种医学 | 136篇 |
外科学 | 301篇 |
综合类 | 40篇 |
一般理论 | 3篇 |
预防医学 | 386篇 |
眼科学 | 16篇 |
药学 | 94篇 |
1篇 | |
中国医学 | 1篇 |
肿瘤学 | 152篇 |
出版年
2022年 | 18篇 |
2021年 | 25篇 |
2019年 | 22篇 |
2018年 | 22篇 |
2016年 | 18篇 |
2015年 | 21篇 |
2014年 | 34篇 |
2013年 | 52篇 |
2012年 | 118篇 |
2011年 | 122篇 |
2010年 | 48篇 |
2009年 | 48篇 |
2008年 | 99篇 |
2007年 | 104篇 |
2006年 | 86篇 |
2005年 | 85篇 |
2004年 | 83篇 |
2003年 | 86篇 |
2002年 | 93篇 |
2001年 | 75篇 |
2000年 | 83篇 |
1999年 | 64篇 |
1998年 | 41篇 |
1997年 | 92篇 |
1996年 | 62篇 |
1995年 | 38篇 |
1994年 | 45篇 |
1993年 | 25篇 |
1992年 | 77篇 |
1991年 | 67篇 |
1990年 | 74篇 |
1989年 | 77篇 |
1988年 | 54篇 |
1987年 | 46篇 |
1986年 | 64篇 |
1985年 | 61篇 |
1984年 | 30篇 |
1983年 | 25篇 |
1982年 | 21篇 |
1981年 | 26篇 |
1980年 | 20篇 |
1979年 | 27篇 |
1978年 | 19篇 |
1977年 | 24篇 |
1976年 | 19篇 |
1975年 | 21篇 |
1974年 | 26篇 |
1973年 | 23篇 |
1972年 | 20篇 |
1967年 | 16篇 |
排序方式: 共有2694条查询结果,搜索用时 15 毫秒
21.
Malaria during pregnancy can result in low birth weight (LBW), an important risk factor for infant mortality. This article reviews the pathological effects of malaria during pregnancy and the implications for the newborn's development and survival. Empirical data from throughout Africa on associations between placental malaria and birth weight outcome, birth weight outcome and infant mortality, and the rates of LBW in areas with various levels of malaria transmission are evaluated to assess the increased risks of LBW and infant mortality associated with malaria. It is estimated that in areas where malaria is endemic, around 19% of infant LBWs are due to malaria and 6% of infant deaths are due to LBW caused by malaria. These estimates imply that around 100,000 infant deaths each year could be due to LBW caused by malaria during pregnancy in areas of malaria endemicity in Africa. 相似文献
22.
23.
Forty-three bronchoalveolar lavage (BAL) specimens from 40 immunocompromised patients were studied for the presence of cytomegalovirus (CMV) by rapid diagnostic methods. DNA in situ hybridization, cytology, and immunofluorescence were compared to conventional cell culture. Eleven (25%) of the 43 BAL samples grew CMV in culture. In situ hybridization detected 6 of these 11 for sensitivity, specificity, and predictive values of positive and negative of 55%, 94%, 75%, and 86%, respectively. Cytology had a sensitivity of 73% and specificity of 100%. Six Papanicolaou-stained cytospins were screened cytologically versus one hybridization cytospin, and the higher sensitivity of cytology may reflect this extensive sampling. The immunofluorescent method had a sensitivity equal to that of cytology (73%): however, the specificity (72%) was significantly less than that of either the probe or cytology. These data suggest that although in situ hybridization can be a rapid, useful method for detecting CMV in BAL specimens, cytology appears to be a more sensitive method. 相似文献
24.
This study investigated the effects of riluzole (Ril), creatine (Cr) and a combination of these treatments on the onset and progression of clinical signs and neuropathology in an animal model of familial amyotrophic lateral sclerosis, the G93A transgenic mouse (n=13-17 per group). The onset of clinical signs was delayed (P<0.05) by about 12 days in all treatment groups compared with control; however, no differences occurred between treatments. All animals were killed at 199 days of age. At the end of the experimental period the severity of clinical signs was less (P<0.05) with all treatments compared with control. Again no differences between treatments were observed. The treatments had no effect on the number of neurons in ventral horns of the lumbar region of the spinal cord. Transgenic mice ingesting Cr displayed elevated (P<0.05) total Cr levels in cerebral hemispheres (5%) and spinal cord (8%), but not skeletal muscles. These data demonstrate that treatment with Ril and Cr were both effective in delaying disease onset and clinical disability. To the age of killing, no additional benefit was conferred by co-administration of Ril and Cr. 相似文献
25.
Activity-induced fiber regeneration in rat soleus muscle 总被引:3,自引:0,他引:3
In an attempt to understand why muscle recovery is limited following atrophy due to limb immobilization, satellite cell activity and muscle fiber regeneration were analyzed in rat soleus muscles. Adult rat hindlimbs were immobilized in plaster casts for a period of two to ten weeks. Soleus muscles were examined by electron microscopy for evidence of fiber degeneration or regeneration, and to quantify satellite cell nuclei. Immunocytochemical localization of embryonic myosin was used to identify regenerating myofibers. Soleus muscle wet weight to body weight ratios for the casted muscles significantly decreased over the 10-week immobilization period. The casted muscles displayed ultrastructural evidence of minor fiber damage, including myofibrillar atrophy, Z-disc disruption, and abnormal triadic junctions. No ultrastructural evidence of regeneration was seen in the casted animals. The number of satellite cells in the casted muscles significantly decreased from 6.4% to 3. 3% by eight to 10 weeks of immobilization. Approximately 1.0% of extrafusal fibers in the control soleus muscles appeared to be regenerating since they expressed embryonic myosin and were of a small diameter, while in casted muscles, only 0.1% of the fibers were embryonic myosin-positive. Following release from immobilization, a reappearance of embryonic myosin-positive fibers was noted within four days of renewed activity. In contrast to control muscles, embryonic myosin-positive fibers in the recovery muscles included both small and large diameter fibers. Subtle changes in functional activity influence muscle damage and subsequent myofiber regeneration. Reduced activity reduces muscle fiber regeneration, while increased activity, as seen by increased hindlimb weight bearing and return to normal activity following immobilization, increase regenerating fibers and also the expression of embryonic myosin in adult fibers. 相似文献
26.
E C Keystone L Poplonski R G Miller R Gorczynski D Gladman K Snow 《Clinical immunology and immunopathology》1988,48(3):325-337
The ability of an anti-CD3 monoclonal antibody (OKT3) to induce proliferation was examined in peripheral blood mononuclear cells (PBM) from 30 patients with rheumatoid arthritis (RA). Controls consisted of 10 patients with osteoarthritis, 12 patients with psoriatic arthritis, and 12 healthy subjects. The results revealed enhanced PBM reactivity in patients with active RA relative to inactive RA patients and all control groups. PBM of patients with mild/moderate clinical disease activity exhibited augmented anti-CD3 reactivity while those with severe disease demonstrated impaired reactivity. Enhanced reactivity was also observed in the active RA group using another anti-CD3 monoclonal antibody (Leu-4). Differences in anti-CD3 dose-response or time kinetics could not account for the results. Studies of enriched T-cell preparations revealed a markedly enhanced anti-CD3 reactivity of RA T-cells relative to normal control T-cells. Monocyte/T-cell mixing experiments revealed no enhanced reactivity of RA monocytes in the anti-CD3 response. RA T-cell preparations depleted of monocytes by limiting dilution reacted significantly more to anti-CD3 in the presence of IL-2 relative to controls. The enhanced reactivity could be accounted for in part by hyperreactivity of the OKT8-bearing subpopulation of T-cells. 相似文献
27.
A. Shore Rhonda Klock P. Lee Krista M. Snow E. C. Keystone 《Journal of clinical immunology》1989,9(2):103-110
We examined regulation of Epstein-Barr virus-induced plaque-forming cell generation in peripheral blood mononuclear cells from several autoimmune and seronegative diseases and correlated these results with Epstein-Barr virus-induced proliferation. We confirmed the defective regulation of Epstein-Barr virus-induced plaque-forming cells in peripheral blood mononuclear cells of patients with rheumatoid arthritis and scleroderma. Peripheral blood mononuclear cells from patients with seronegative arthropathies and chronic infective inflammation (cystic fibrosis) had normal regulation of Epstein-Barr virus-induced plaque-forming cells. Peripheral blood mononuclear cells from rheumatoid arthritis had excessive plaque-forming cell generation in the face of a normally regulated decrease in Epstein-Barr virus-induced proliferation. In contrast, peripheral blood mononuclear cells from scleroderma had defective suppression of both Epstein-Barr virus-induced proliferation and plaque-forming cell generation. Thus, impaired regulation of Epstein-Barr virus-induced plaque-forming cell generation is a common feature of autoimmune disease and demonstrates some specificity for these disorders. 相似文献
28.
Sulfated glycosaminoglycans: a common constituent of all amyloids? 总被引:13,自引:0,他引:13
A D Snow J Willmer R Kisilevsky 《Laboratory investigation; a journal of technical methods and pathology》1987,56(1):120-123
In the present investigation, we analyzed whether sulfated glycosaminoglycans are a common constituent in many different types of amyloid. Serial sections of amyloidotic tissue were stained for the presence of: (a) amyloid by using Congo Red, and (b) glycosaminoglycans by using both the sodium sulfate Alcian blue method and Alcian blue, pH 5.7, with varying concentrations of magnesium chloride. Our results show that sulfated glycosaminoglycans are always associated anatomically with amyloid deposits regardless of the nature of the protein deposited. Sulfated glycosaminoglycans were found in tissues containing AA, AL, inherited cutaneous amyloid, and senile cardiac amyloid (prealbumin). Additionally, we provide evidence that sulfated glycosaminoglycans are closely associated with the amyloid of medullary carcinoma of the thyroid (prothyrocalcitonin), and neuritic plaques, neurofibrillary tangles, and congophilic angiopathy in Alzheimer's disease. It is postulated that these sulfated glycosaminoglycans can influence the folding of diverse proteins such that all forms of amyloid show a significant beta-pleated sheet component. 相似文献
29.
A reflex increase in heart rate from distension of the junction between the superior vena cava and the right atrium 总被引:1,自引:3,他引:1
1. Localized distension of the junction between the superior vena cava and the right atrium without obstructing venous return caused an increase in heart rate.2. This increase in heart rate was a reflex response; the afferent path was in the vagi and the efferent solely in the sympathetic nerves.3. The receptors most likely to be stimulated by the distension of the junction between the superior vena cava and the right atrium are the right atrial receptors located on the endocardial surface of the intrapericardial portion of the superior vena caval-right atrial junction. 相似文献
30.
In a DUI offender sample, four drinking reason factors are regressed on alcohol consumption variables and frequency of drinking in seven types of locations. Drinking for "pleasure" and "opposite sex/drunkenness" reasons are associated with both quantity consumed per occasion and away-from-home locations such as automobiles, bars, and parties, suggesting high traffic accident risk. "Escapism" reasons are related to quantity consumed per occasion, but are only weakly associated with specific locations; and "sociability" reasons are associated with drinking in friends' homes, but are not related to high consumption levels. Implications for DUI countermeasures are discussed. 相似文献