全文获取类型
收费全文 | 18844篇 |
免费 | 1168篇 |
国内免费 | 55篇 |
专业分类
耳鼻咽喉 | 132篇 |
儿科学 | 650篇 |
妇产科学 | 474篇 |
基础医学 | 2343篇 |
口腔科学 | 207篇 |
临床医学 | 2654篇 |
内科学 | 3858篇 |
皮肤病学 | 256篇 |
神经病学 | 1767篇 |
特种医学 | 406篇 |
外科学 | 2129篇 |
综合类 | 155篇 |
一般理论 | 8篇 |
预防医学 | 2050篇 |
眼科学 | 174篇 |
药学 | 1067篇 |
中国医学 | 16篇 |
肿瘤学 | 1721篇 |
出版年
2023年 | 114篇 |
2022年 | 169篇 |
2021年 | 392篇 |
2020年 | 221篇 |
2019年 | 343篇 |
2018年 | 408篇 |
2017年 | 354篇 |
2016年 | 367篇 |
2015年 | 383篇 |
2014年 | 577篇 |
2013年 | 848篇 |
2012年 | 1215篇 |
2011年 | 1272篇 |
2010年 | 740篇 |
2009年 | 655篇 |
2008年 | 1134篇 |
2007年 | 1264篇 |
2006年 | 1228篇 |
2005年 | 1272篇 |
2004年 | 1251篇 |
2003年 | 1127篇 |
2002年 | 1034篇 |
2001年 | 326篇 |
2000年 | 321篇 |
1999年 | 291篇 |
1998年 | 211篇 |
1997年 | 194篇 |
1996年 | 171篇 |
1995年 | 134篇 |
1994年 | 127篇 |
1993年 | 126篇 |
1992年 | 182篇 |
1991年 | 168篇 |
1990年 | 147篇 |
1989年 | 117篇 |
1988年 | 119篇 |
1987年 | 105篇 |
1986年 | 95篇 |
1985年 | 95篇 |
1984年 | 123篇 |
1983年 | 78篇 |
1982年 | 76篇 |
1981年 | 64篇 |
1980年 | 56篇 |
1979年 | 60篇 |
1978年 | 40篇 |
1977年 | 31篇 |
1976年 | 37篇 |
1974年 | 26篇 |
1972年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Bonnie L. Westra R.N. Ph.D. Laura Cullen R.N. M.A. Donna Brody R.N. M.S.N. Patricia Jump R.N. M.S. Letitia Geanon R.N. M.S. Ellen Milad R.N. M.S. 《Public health nursing (Boston, Mass.)》1995,12(6):393-399
Abstract Client (patient) satisfaction has been studied extensively in the health care sector, yet those receiving home health care services have been the focus of few studies. The purpose of this study was to test the reliability and validity of the Home Care Client Satisfaction Instrument (HCCSI). A total of 400 clients, randomly selected from 20 randomly chosen home care agencies in one state, completed the HCCSI and demographic form. Most respondents were older adults with multiple health problems and their families or informal support systems. Since data were skewed, item analysis was used. The revised instrument (HCCSI-R) is unidimensional and includes 12 items rated on a 5-point Likert scale measuring specific aspects of care. In addition, there are three global measures of satisfaction rated on a 10-point scale. All items except one had significant item-total correlations greater than .59. The total score correlates with likeliness to recommend the agency to others (.37, p = .0001), showing some evidence for criterion-related validity. 相似文献
102.
French Donna L. Häglund Bert O. Himmelstein Kenneth J. Mauger John W. 《Pharmaceutical research》1995,12(10):1513-1520
Purpose. The objective of this study is to correlate drug release mechanism with measured drug concentration profiles in gel layers of Carbopol® matrices containing mesalamine or benzoic acid.
Methods. Release rate experiments with Carbopol® matrices were performed using a rotating disk apparatus. Matrices were frozen and the gel layer in the matrices was sliced using a microtome in a cryostat. Drug concentration profiles were determined by direct measurement of the concentration of the drug in the gel slices. The pH of the slices was measured using microelectrodes, and water content was measured by Karl Fisher titration.
Results. The concentration gradient in mesalamine matrices decreased over time and correlated with square root of time release rate kinetics. The concentration profiles of benzoic acid were unchanged over time and correlated with zero order release rate kinetics. Carbopol gel layers were highly hydrated (93–95% water). Gel layers in matrices with mesalamine had a more alkaline microenvironmental pH. This higher pH resulted in increased growth of the thickness of the gel layer and a reduction drug diffusivity in comparison to benzoic acid matrices.
Conclusions. The release rate kinetics of mesalamine and benzoic acid correlated to the measured concentration profiles. The shape of the concentration profiles is determined by the rate of growth of the Carbopol® gel layer and drug diffusivity. 相似文献
103.
M. C. Miller R. C. Byrd N. Ensslin W. C. Feldman M. S. Krick T. H. Prettyman P. A. Russo 《Applied radiation and isotopes》1997,48(10-12)
Monte Carlo simulations were carried out to simulate the response of a boron-loaded plastic scintillator array. These detectors offer potential advantages compared to moderated 3He systems because of their fast response and high efficiency. Tallies were made of neutron capture probability as a function of time and the results were coupled to assay variance estimates to evaluate detector performance. Orders-of-magnitude reductions in count time relative to a 50% efficient thermal counter are possible, in principle, for high (α,n) samples. 相似文献
104.
Marilyn Rodney Carla Clasen Gloria Goldman Ronald Markert Donna Deane 《Journal of community health》1998,23(5):371-381
The title Community Health Advocate (CHA) is one of thirty or more titles used throughout the world for an indigenous outreach worker who is trusted and respected in his or her community and who serves as a bridge between peers and health professionals. In 1992, the Center for Healthy Communities in Dayton, Ohio developed a program to train as Advocates people indigenous to the communities in which they would be working. Since the first CHAs began work in January 1993, the effectiveness of the program has been evaluated from three perspectives: the Community Health Advocates, the managers directors of the community sites at which the CHAs work, and the clients with whom the CHAs work. Advocates indicated that the training program adequately prepared them for their roles and functions. They also identified systematic frustrations and barriers that made it more difficult for them to perform their job. Community site directors and community leaders indicated that the CHAs were considered a positive force in meeting client needs and facilitating independence, and were very effective in outreach and coordination of resources. A survey of CHA clients revealed an overwhelmingly positive response to the Advocate's work, validating the belief that CHAs can fill an important niche in the health care community. The three evaluation processes described in this paper helped to document the need for and the effectiveness of this program and can serve as a model for similar programs. 相似文献
105.
106.
Randomised prospective study on renal effects of two different contrast media in humans: protective role of a calcium channel blocker 总被引:6,自引:0,他引:6
Contrast media affect renal hemodynamics. Hyperosmolality is regarded as the major factor responsible for renal hemodynamic changes. In this study, the role of osmolality was evaluated in 30 hospitalized patients without risk factors during intravenous pyelography. Contrast media with low and high osmolality were used. In addition, nifedipine was administered before infusion of high-osmolality contrast to evaluate the role of calcium ions in radiocontrast-induced changes of renal hemodynamics. Hyperosmolar contrast reduced renal plasma flow and glomerular filtration rate. Calcium channel blocker prevented changes of renal hemodynamics. Hyperosmolality appears the most likely factor affecting renal hemodynamics during hyperosmolar radiocontrast infusion. Calcium channel blocker may prevent renal changes due to hyperosmolar medium. 相似文献
107.
108.
Aitken R.John; Buckingham Donna W.; Brindle James; Gomez Emelio; Baker H.W.Gordon; Irvine D.Stewart 《Human reproduction (Oxford, England)》1995,10(8):2061-2071
The addition of luminol to unprocessed semen samples resultedin the generation of chemiluminescent signals, the intensityof which was highly correlated with the level of leukocyte contamination.Despite the spontaneous oxidant-generating capacity of seminalleukocytes, no correlations were observed between leukocytecontamination and the fertility status of the subjects or anyaspect of the semen profile, including the motility of the spermatozoaor their performance in a hyaluronate penetration assay. Luminol-dependentchemiluminescence and leukocyte contamination were also correlatedin washed sperm suspensions prepared either by repeated centrifugationor on discontinuous Percoll gradients. However, in such spermsuspensions, the spontaneous generation of oxidants by contaminatingleukocytes (>2x104 leukocytes/ml) was invariably associatedwith a decreased capacity for movement. Moreover, causativeassociations between leukocyte contamination, reactive oxygenspecies generation, lipid peroxidation and impaired sperm motilitywere revealed by experiments involving the selective additionor removal of activated leukocytes. From these observationswe can conclude that low concentrations of leukocytes are acommon feature of the human ejaculate and can impair sperm function,particularly in the absence of seminal plasma. These findingshave implications for our understanding of the importance ofleukocytospermia in defining the fertility of human spermatozoain vivo and in vitro. 相似文献
109.
Helen E. Pearson Donna L. Smith-Harrison Nancy K. Rosenblatt Bertram R. Payne 《Experimental neurology》1993,119(2)
The short-term metabolic response of immature retinal ganglion cells to destruction of their target cells in the dorsal lateral geniculate nucleus (dLGN) was assessed in newborn cats. Retrograde degeneration of virtually all dLGN cells was induced by ablation of the 13 contiguous areas of visual cortex on the day of birth. The metabolic response of retinal ganglion cells to this loss of target cells in dLGN was determined by exposing the ganglion cell layer to tritiated uridine, a precursor of RNA. Control measurements were made from unoperated littermates. Following sectioning and processing of the retinae from both groups of kittens for autoradiography, silver grain densities overlying the cellular profiles in the ganglion cell layer were calculated. These calculations revealed levels of uridine incorporation at Postnatal Day 4 in both groups of kittens significantly higher than at either Postnatal Day 2 or 7, but no significant differences between the two groups on any day examined. These results show that the level of RNA synthesis in retinal ganglion cells increases temporarily during the first postnatal week and that this synthesis is unaffected by the death of target cells in the dLGN. The temporary increase may be related to the establishment of synaptic connections on retinal ganglion cells by their afferent bipolar and amacrine neurons in the inner nuclear layer. 相似文献
110.
10 patients operated on for anterior communicating artery aneurysm (ACoA) underwent to neuropsychological examination one year after surgery, in order to detect eventual behavioural and/or amnestic disorders, already described by others in a wide percentage of such patients. Even if after accurate neurological examination the therapeutic results were defined as "good", 60% circa of our patients present amnestic and/or behavioural disturbances. Possible correlations between neuropsychological tests finding and intraoperative occurrences (early aneurysm rupture, gyrectomy etc.) are considered and discussed. 相似文献