全文获取类型
收费全文 | 2894687篇 |
免费 | 233229篇 |
国内免费 | 5495篇 |
专业分类
耳鼻咽喉 | 42726篇 |
儿科学 | 88426篇 |
妇产科学 | 78412篇 |
基础医学 | 409331篇 |
口腔科学 | 84144篇 |
临床医学 | 262094篇 |
内科学 | 561200篇 |
皮肤病学 | 58824篇 |
神经病学 | 242949篇 |
特种医学 | 115999篇 |
外国民族医学 | 1042篇 |
外科学 | 440231篇 |
综合类 | 72570篇 |
现状与发展 | 3篇 |
一般理论 | 1170篇 |
预防医学 | 233766篇 |
眼科学 | 69480篇 |
药学 | 216180篇 |
4篇 | |
中国医学 | 5373篇 |
肿瘤学 | 149487篇 |
出版年
2018年 | 28618篇 |
2016年 | 24538篇 |
2015年 | 27875篇 |
2014年 | 40230篇 |
2013年 | 61435篇 |
2012年 | 82706篇 |
2011年 | 87206篇 |
2010年 | 51319篇 |
2009年 | 49055篇 |
2008年 | 82722篇 |
2007年 | 88628篇 |
2006年 | 89234篇 |
2005年 | 87113篇 |
2004年 | 84311篇 |
2003年 | 81414篇 |
2002年 | 80140篇 |
2001年 | 130006篇 |
2000年 | 134492篇 |
1999年 | 113893篇 |
1998年 | 33476篇 |
1997年 | 30554篇 |
1996年 | 30129篇 |
1995年 | 29136篇 |
1994年 | 27449篇 |
1993年 | 25574篇 |
1992年 | 93017篇 |
1991年 | 89774篇 |
1990年 | 86899篇 |
1989年 | 83716篇 |
1988年 | 78022篇 |
1987年 | 77035篇 |
1986年 | 72872篇 |
1985年 | 69947篇 |
1984年 | 53442篇 |
1983年 | 45715篇 |
1982年 | 28237篇 |
1981年 | 25244篇 |
1980年 | 23767篇 |
1979年 | 51274篇 |
1978年 | 36322篇 |
1977年 | 30596篇 |
1976年 | 28597篇 |
1975年 | 30331篇 |
1974年 | 37519篇 |
1973年 | 35870篇 |
1972年 | 33635篇 |
1971年 | 31077篇 |
1970年 | 29400篇 |
1969年 | 27644篇 |
1968年 | 25150篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A family with two members (two generations) exhibiting Turner syndrome is described. Cytogenetic studies on these individuals showed the presence of multiple X chromosome changes. Evidence is presented to show that the maternally inherited X chromosome is the chromosome involved in the structural alterations observed. The effect of a tendency of the maternal X chromosome to break at specific sites on the development of the Turner phenotype and abnormal karyology is discussed. 相似文献
992.
J M Debets R Kampmeijer M P van der Linden W A Buurman C J van der Linden 《Critical care medicine》1989,17(6):489-494
Tumor necrosis factor (TNF) cachectin has been implicated as an important host mediator responsible for shock and multiple organ failure (MOF) observed during sepsis. Using a sensitive enzyme-linked immunosorbent assay, we measured plasma TNF levels in 43 septic patients suffering from a broad range of diseases. Measurements were taken on the day that sepsis was diagnosed. Eleven patients had detectable TNF plasma levels ranging from 10 to 100 pg/ml (TNF-positive group); in 32 patients circulating TNF could not be detected (TNF-negative group). The groups did not differ significantly as to age, underlying disease, percentage positive bacteremia and bacteriologic profile, sepsis score, and extent of MOF. Eight (73%) of 11 TNF-positive patients died from sepsis during ICU stay, vs. 11 (34%) of 32 TNF-negative patients (p less than .05). This study demonstrates that sepsis is accompanied by detectable circulating TNF in 25% of the cases, and for these patients mortality is twice that for comparable TNF-negative patients. 相似文献
993.
In 1981 a statewide program supplying free insulin to 3,720 patients of state health clinics was discontinued. We attempted to assess whether this action had an adverse effect medically and financially on those concerned. A computer randomized sample of 351 patients (9%) was studied by personal interview and questionnaire. Information obtained focused on certain events that occurred 18 months before and after the program ceased. Measurements used to determine medical impact were number of hospitalizations, emergency room and physician visits, changes in weight and glucose levels, and episodes of ketoacidosis. Financial impact was measured by cost of hospitalization and physician visits. Our results revealed no significant changes in any of the medical parameters studied except for fasting serum glucose levels above 300 mg/dl, which occurred less frequently after the free insulin program was discontinued. There were fewer hospitalizations, more visits to physicians, and no change in number of emergency room visits after discontinuance of the free program. The overall cost saving was estimated to be +883,558 for the 18-month study period, in addition to the +550,000 the plan had been costing the state. 相似文献
994.
H Ku?nierczyk J Matuszyk C Radzikowski 《Archivum immunologiae et therapiae experimentalis》1989,37(5-6):547-556
The alkylating agent ifosfamide synthesized according to own method at the Institute of Pharmaceutical Industry, Warsaw, was compared in biological evaluations with Holoxan (Asta-Werke's ifosfamide). No significant differences between tested compounds were found in respect of acute toxicity and antitumor activity in experimental systems in mice. 相似文献
995.
996.
R S Chadwick J Ohayon M Lewkowicz 《Proceedings of the National Academy of Sciences of the United States of America》1989,86(9):2996-2999
A fluid-fiber-collagen stress tensor is used to describe the rheology of the left ventricle of the heart. Linear theory is used to find the equilibrium solutions for the end-diastolic and end-systolic states of general axisymmetric shapes that are small perturbations of a thick-walled finite cylinder. The general problem can be studied by superposing the effects of variable midwall radius but constant wall thickness with those of variable wall thickness but constant midwall radius. A Fourier series representation is used to describe the midwall radius and thickness functions. Numerical calculations are performed to determine the deformed geometry and spatial distributions of tissue pressure, stresses, and fiber strains. The calculations proved to be highly accurate when compared to an analytical solution obtained for the special case of no fibers. The results show significant longitudinal differences when compared to results for the cylindrical geometry, with more sensitivity to variation in wall thickness than to variation in midwall radius. 相似文献
997.
J R Keane 《Archives of neurology》1989,46(7):761-762
A review of 96 consecutive patients who suffered neuro-ophthalmologic injuries in motorcycle accidents revealed a wide range of findings. These findings were similar to signs associated with other forms of closed-head trauma, aside from a higher incidence of trochlear nerve palsies. 相似文献
998.
A retrospective analysis of the results of 27,801 cervical smears from one year in a community laboratory was undertaken. This represented 23,820 individual patients. Abnormalities were seen in 9.3% of patients. Three point seven percent of patients had benign abnormalities, 5.5% had cervical intraepithelial neoplasia and 0.1% had major abnormalities. The incidence of cervical epithelial abnormality was highest in the 15-34 age group but major abnormalities were seen most often in the 55+ age group. Human papillomavirus was more commonly seen in the youngest age group. The presence of inflammation was reported in 65% of the smears. Thirty percent of smears had no endocervical cells and 0.6% were grossly inadequate. Fifteen percent of patients had repeat smears and 3% of total smears were judged unnecessary. Forty two point six percent of patients less than 55 years of age in the laboratory population base had a smear but only 7.9% of those over 55. 相似文献
999.
The in vitro ability of bacterial purified antigenic fractions to interfere with the immune system has been investigated on human mononuclear cells from peripheral blood. Exposure of purified monocytes to the drug at concentrations from 1 to 1000 micrograms/ml, for different periods from 0 to 18 h, significantly increased cell-mediated cytotoxicity against TU5 target cells. Moreover, monocytes exposed for 1 to 18 h to drug concentrations from 0.1 to 1000 micrograms/ml released significant amounts of tumor necrosis factor alpha in a dose-dependent manner in the culture supernatants. The drug was also tested on natural killer (NK) cell activity; mononuclear cells exposed to antigenic fractions for different periods showed a significant increase of NK cytotoxic activity against K562 target cells after 3 and 6, but not 0 and 18 h. Active concentrations were from 1 to 100 micrograms/ml, higher and lower doses being ineffective. Bacterial purified antigenic fractions thus have some ability to interfere in vitro with mechanisms of cytolysis mediated by cells and soluble factors. 相似文献
1000.
R J Smith 《The British journal of ophthalmology》1989,73(7):481-482