全文获取类型
收费全文 | 5688篇 |
免费 | 347篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 116篇 |
儿科学 | 221篇 |
妇产科学 | 85篇 |
基础医学 | 641篇 |
口腔科学 | 236篇 |
临床医学 | 429篇 |
内科学 | 1436篇 |
皮肤病学 | 108篇 |
神经病学 | 520篇 |
特种医学 | 134篇 |
外科学 | 987篇 |
综合类 | 38篇 |
一般理论 | 2篇 |
预防医学 | 498篇 |
眼科学 | 56篇 |
药学 | 292篇 |
中国医学 | 15篇 |
肿瘤学 | 242篇 |
出版年
2023年 | 32篇 |
2022年 | 41篇 |
2021年 | 89篇 |
2020年 | 69篇 |
2019年 | 108篇 |
2018年 | 155篇 |
2017年 | 108篇 |
2016年 | 111篇 |
2015年 | 180篇 |
2014年 | 168篇 |
2013年 | 248篇 |
2012年 | 378篇 |
2011年 | 378篇 |
2010年 | 223篇 |
2009年 | 171篇 |
2008年 | 345篇 |
2007年 | 326篇 |
2006年 | 280篇 |
2005年 | 266篇 |
2004年 | 235篇 |
2003年 | 217篇 |
2002年 | 242篇 |
2001年 | 158篇 |
2000年 | 156篇 |
1999年 | 142篇 |
1998年 | 46篇 |
1997年 | 52篇 |
1996年 | 42篇 |
1995年 | 39篇 |
1994年 | 31篇 |
1993年 | 34篇 |
1992年 | 80篇 |
1991年 | 79篇 |
1990年 | 73篇 |
1989年 | 76篇 |
1988年 | 83篇 |
1987年 | 54篇 |
1986年 | 43篇 |
1985年 | 64篇 |
1984年 | 29篇 |
1983年 | 28篇 |
1980年 | 19篇 |
1979年 | 41篇 |
1978年 | 20篇 |
1977年 | 19篇 |
1976年 | 20篇 |
1975年 | 26篇 |
1974年 | 25篇 |
1973年 | 20篇 |
1969年 | 24篇 |
排序方式: 共有6056条查询结果,搜索用时 31 毫秒
31.
32.
Brief report: cognitive functioning in children with Tourette's syndrome with and without comorbid ADHD 总被引:12,自引:0,他引:12
Brand N Geenen R Oudenhoven M Lindenborn B van der Ree A Cohen-Kettenis P Buitelaar JK 《Journal of pediatric psychology》2002,27(2):203-208
OBJECTIVE: To examine whether patients with Tourette's syndrome (TS) with and without comorbid attention deficit and hyperactivity disorder (ADHD) differ in cognitive functioning and whether a higher level of cognitive functioning is associated with severity of TS symptoms and psychosocial functioning. METHODS: Cognitive functioning, symptom severity, and psychosocial functioning were examined in 40 patients (33 boys, 7 girls; age range 6-18 years) with TS, of whom 17 had the comorbid diagnosis of ADHD. RESULTS: Patients with a comorbid ADHD diagnosis evidenced poorer performance than those with TS alone with respect to severity of TS symptoms, psychosocial functioning, verbal and performance intelligence, and word fluency, but not on tests of cognitive flexibility. Psychosocial functioning was predicted by symptom severity, but not by intelligence or fluency. CONCLUSIONS: Results confirm prior findings that comorbid ADHD is associated with more TS symptoms and worse psychosocial and cognitive functioning, and motivate whether cognitive flexibility plays a role in moderating the deleterious psychosocial effects of Tourette's syndrome and ADHD. 相似文献
33.
34.
Sylviane Tardivel Lea Razanamaniraka Tilman Drüeke Bernard Lacour 《Pflügers Archiv : European journal of physiology》1995,429(4):470-476
The effect of sorbitol on Ca uptake by isolated ileal epithelial cells was investigated. Intestinal cells were isolated from rat ileum by mechanical vibration.45Ca uptake was approximately 2 times higher in cells exposed to 200 mM sorbitol ofd-alanine than in control cells. This enhancing effect of sorbitol on percentage Ca uptake decreased with increasing Ca concentrations in the incubation medium suggesting an effect on Ca entry velocity. The addition of 10 M nifedipine or 200 M verapamil to the incubation medium was devoid of any effect on Ca uptake in ileal cells, whereas 100 M trifluoperazine or chlorpromazine abolished the stimulatory effect of sorbitol. Finally, the effect of sorbitol on isolated cells was independent of a measurable change of cellular ATP content. In conclusion, the stimulatory effect of sorbitol on ileal Ca uptake is probably exerted through mechanisms other than an increase in intracellular ATP concentration. Sorbitol may enhance enterocyte Ca transport via a direct interaction with calmodulin and/or the Ca pump. It may also exert its effect through an inhibition of the basolateral Na Ca exchanger. 相似文献
35.
36.
A comparative study of the expression of cytotoxic proteins in allergic contact dermatitis and psoriasis: spongiotic skin lesions in allergic contact dermatitis are highly infiltrated by T cells expressing perforin and granzyme B 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yawalkar N Hunger RE Buri C Schmid S Egli F Brand CU Mueller C Pichler WJ Braathen LR 《The American journal of pathology》2001,159(3):803-808
Recent reports indicate that cytotoxic T cells are critically involved in contact hypersensitivity reactions in animals. In this study we sought to investigate the in vivo expression of cytotoxic granule proteins in the elicitation phase of allergic contact dermatitis in humans. Skin biopsy specimens were obtained from patients with allergic contact dermatitis (n = 8) and psoriasis (n = 6) and from controls with normal skin (n = 6). Expression of perforin and granzyme B was investigated by in situ hybridization and immunohistochemistry. In contrast to normal skin and psoriasis, a significant enhancement of perforin and granzyme B gene expression and immunoreactivity was observed in the mononuclear cell infiltrate of allergic contact dermatitis. Immunoreactivity for perforin and granzyme B was mainly found in the cytoplasm of lymphocytic cells, which were located in the dense perivascular infiltrate as well as at sites of marked spongiosis in the epidermis. Double immunostaining revealed that both CD4+ and CD8+ T cells are capable of expressing perforin and granzyme B. In conclusion, our data suggest that T-cell-mediated mechanisms involving cytotoxic granule proteins may elicit epidermal cell injury in vivo and thereby strongly contribute to the development of allergic contact dermatitis in humans. 相似文献
37.
Secretion of Igs and surface expression of HLA antigens was examined in lymphoid cells as a function of temp. Upon reducing the temp from 37 to 20 degrees C a progressive decrease in the secretion of Ig and surface expression of HLA antigens was noted. When the status of the oligosaccharides present on these glycoproteins was examined, conversion of high-mannose [endo-beta-N-acetylglucosaminidase-(Endo H) sensitive] to complex-type (Endo H resistant) oligosaccharides diminished with decreasing temp. At no time was an accumulation of Endo H resistant glycoproteins seen intracellularly. These results show that the phenomenon observed for synthesis and intracellular transport of viral glycoproteins in epithelial cells at reduced temp, namely intracellular accumulation of viral glycoproteins carrying complex sugar moieties, does not necessarily apply to glycoprotein transport in lymphoid cells. A difference in subcellular organization of epithelial and lymphoid cells may be responsible for this discrepancy. 相似文献
38.
A computer protocol to predict myocardial infarction in emergency department patients with chest pain 总被引:42,自引:0,他引:42
L Goldman E F Cook D A Brand T H Lee G W Rouan M C Weisberg D Acampora C Stasiulewicz J Walshon G Terranova 《The New England journal of medicine》1988,318(13):797-803
To achieve more appropriate triage to the coronary care unit of patients presenting with acute chest pain, we used clinical data on 1379 patients at two hospitals to construct a simple computer protocol to predict the presence of myocardial infarction. When we tested this protocol prospectively in 4770 patients at two university hospitals and four community hospitals, the computer-derived protocol had a significantly higher specificity (74 vs. 71 percent) in predicting the absence of infarction than physicians deciding whether to admit patients to the coronary care unit, and it had a similar sensitivity in detecting the presence of infarction (88.0 vs. 87.8 percent). Decisions based solely on the computer protocol would have reduced the admission of patients without infarction to the coronary care unit by 11.5 percent without adversely affecting the admission of patients in whom emergent complications developed that required intensive care. Although this protocol should not be used to override careful clinical judgment in individual cases, the computer protocol for the most part yields accurate estimates of the probability of myocardial infarction. Decisions about admission to the coronary care unit based on the protocol would have been as effective as those actually made by the unaided physicians who cared for the patients, and less costly. Whether physicians who are aided by the protocol perform better than unaided physicians cannot be determined without further study. 相似文献
39.
C E Bacchi R A Schmidt M Brand?o R Scapulatempo J C Costa F C Schmitt 《Archives of pathology & laboratory medicine》1990,114(8):899-901
We describe a case of paraganglioma arising in the spermatic cord, which is an extremely rare location. Immunohistochemical studies characterized two types of cells: (1) polygonal cells expressing neuron-specific enolase, chromogranin A, and synaptophysin and (2) S100 protein-positive sustentacular cells. Electron microscopy revealed that within the cytoplasm of the polygonal cells, there were electron-dense granules whose morphological appearance was consistent with that of neurosecretory granules. Paraganglioma of the spermatic cord may originate from embryonic chromaffin cells that have followed the testis into the scrotum. 相似文献
40.
Recessively inherited L-DOPA-responsive parkinsonism in infancy caused by a point mutation (L205P) in the tyrosine hydroxylase gene 总被引:4,自引:0,他引:4