全文获取类型
收费全文 | 23398篇 |
免费 | 2095篇 |
国内免费 | 25篇 |
专业分类
耳鼻咽喉 | 221篇 |
儿科学 | 664篇 |
妇产科学 | 583篇 |
基础医学 | 2754篇 |
口腔科学 | 414篇 |
临床医学 | 2396篇 |
内科学 | 4814篇 |
皮肤病学 | 405篇 |
神经病学 | 2171篇 |
特种医学 | 919篇 |
外国民族医学 | 3篇 |
外科学 | 3428篇 |
综合类 | 518篇 |
一般理论 | 43篇 |
预防医学 | 2491篇 |
眼科学 | 313篇 |
药学 | 1553篇 |
中国医学 | 30篇 |
肿瘤学 | 1798篇 |
出版年
2021年 | 355篇 |
2020年 | 202篇 |
2019年 | 397篇 |
2018年 | 503篇 |
2017年 | 343篇 |
2016年 | 319篇 |
2015年 | 414篇 |
2014年 | 573篇 |
2013年 | 852篇 |
2012年 | 1162篇 |
2011年 | 1197篇 |
2010年 | 761篇 |
2009年 | 677篇 |
2008年 | 1115篇 |
2007年 | 1199篇 |
2006年 | 1205篇 |
2005年 | 1169篇 |
2004年 | 1070篇 |
2003年 | 1001篇 |
2002年 | 914篇 |
2001年 | 602篇 |
2000年 | 632篇 |
1999年 | 573篇 |
1998年 | 323篇 |
1997年 | 259篇 |
1996年 | 268篇 |
1995年 | 271篇 |
1994年 | 198篇 |
1993年 | 192篇 |
1992年 | 428篇 |
1991年 | 419篇 |
1990年 | 362篇 |
1989年 | 384篇 |
1988年 | 356篇 |
1987年 | 338篇 |
1986年 | 311篇 |
1985年 | 317篇 |
1984年 | 263篇 |
1983年 | 224篇 |
1982年 | 176篇 |
1981年 | 161篇 |
1979年 | 245篇 |
1978年 | 182篇 |
1977年 | 152篇 |
1975年 | 148篇 |
1974年 | 151篇 |
1973年 | 190篇 |
1972年 | 186篇 |
1971年 | 158篇 |
1969年 | 147篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
12.
13.
14.
Taylor Moran-Gates Christopher Grady Young Shik Park Ross J Baldessarini Frank I Tarazi 《European neuropsychopharmacology》2007,17(6-7):448-455
The atypical antipsychotic risperidone is often prescribed to pediatric patients with neuropsychiatric disorders, though its effects on the developing brain remain unclear. Accordingly, we studied the effects of repeated treatment of risperidone on dopamine receptors in brain regions of juvenile rat. Levels of dopamine receptors (D(1), D(2), D(3), D(4)) in forebrain regions of juvenile rats were quantified after 3 weeks of treatment with three different doses of risperidone (0.3, 1.0 and 3.0 mg/kg) and compared findings to those in adult rats treated with risperidone (3.0 mg/kg/day) previously. Risperidone (at 1.0 and 3.0 mg/kg/day) increased levels of D(1) receptors in nucleus accumbens and caudate-putamen of juvenile, but not adult rats. Conversely, all three doses of risperidone dose-dependently increased D(2) labeling in medial prefrontal cortex and hippocampus, and D(4) receptor in nucleus accumbens, caudate-putamen and hippocampus of juvenile animals as well as in adults. Only the high dose of risperidone (3.0 mg/kg) increased D(2) receptors in caudate-putamen in both juvenile and adult brain. D(3) receptors were not altered by risperidone in any brain region at any dose or age. The findings indicate dose-dependent effects of risperidone on dopamine receptors in developing animals, and that juvenile animals are more sensitive than adults to the cerebral effects of risperidone. 相似文献
15.
Jeffery H Wootton Anthony B Ross Chris J Diederich 《International journal of hyperthermia》2007,23(8):609-622
PURPOSE: This study was designed to assess pelvic bone temperature during typical treatment regimens of transurethral ultrasound thermal ablation of the prostate to establish guidelines for limiting bone heating. METHODS: Treatment with transurethral planar, curvilinear, and sectored tubular applicators was simulated using an acoustic and biothermal pelvic model that accommodates applicator sweeping, boundary temperature control, and changes in perfusion and attenuation with thermal dose to more accurately model ultrasound energy penetration. The effects of various parameters including power and frequency (5-10 MHz) on bone heating were assessed for a range of prostate cross-sections (3-5 cm) and bone distances (1-3 cm). RESULTS: All devices can produce significant bone heating (temperatures >50 degrees C, thermal dose >240 EM(43 degrees C)) without optimization of applied frequency or power for bone <3 cm from the prostate boundary. In small glands ( approximately 3 cm) increasing operating frequency of curvilinear and planar devices can increase bone temperatures, whereas the tubular applicator can be used at 10 MHz to avoid likely bone damage. In larger prostates (4-5 cm wide) increasing frequency reduces bone heating but can substantially increase treatment time. Lowering power can reduce bone temperature but may increase thermal dose by increasing treatment duration. All applicators can be used to treat glands 4-5 cm with limited bone heating by selecting appropriate power and frequency. CONCLUSIONS: Pubic bone heating during ultrasound thermal therapy of the prostate can be substantial in certain situations. Successful realization of this therapy will require patient-specific treatment planning to optimally determine power and frequency in order to minimize bone heating. 相似文献
16.
17.
18.
Relaxin down-regulates renal fibroblast function and promotes matrix remodelling in vitro. 总被引:1,自引:0,他引:1
Rosemary Masterson Tim D Hewitson Kristen Kelynack Marina Martic Laura Parry Ross Bathgate Ian Darby Gavin Becker 《Nephrology, dialysis, transplantation》2004,19(3):544-552
BACKGROUND: Renal fibroblasts are important effector cells in tubulointerstitial fibrosis, with experimental antifibrotic strategies focusing on the functional down-regulation of these cells. Several experimental models of fibrosis have provided evidence for the effectiveness of the polypeptide hormone relaxin as a potential antifibrotic agent. This study was conducted to further elucidate the antifibrotic mechanisms of relaxin on renal fibroblasts in vitro. METHODS: Rat cortical fibroblasts were obtained from outgrowth culture of renal tissue isolated from kidneys 3 days post-unilateral ureteric obstruction and constituted 100% of cells studied. A relaxin radio-receptor assay was used to establish binding of relaxin to renal fibroblasts in vitro. Functional studies then examined the effects of H2 relaxin (0, 1, 10 and 100 ng/ml) on fibroblast kinetics, expression of alpha-smooth muscle actin (alpha-SMA), total collagen synthesis, collagenase production and collagen-I lattice contraction. CTGF mRNA expression was also measured by northern analysis. RESULTS: H2 relaxin bound with high affinity to rat renal fibroblasts, but receptor numbers were low. Consistent with its previously reported bimodal effect, transforming growth factor (TGF-beta 1) reduced fibroblast proliferation, an effect abrogated by H2 relaxin. Fibroblasts exposed to H2 relaxin (100 ng/ml) for 24 h demonstrated decreased immunostaining for alpha-SMA and reduced alpha-SMA protein expression compared with controls. There was a trend for a relaxin-mediated reduction in total collagen synthesis and alpha 1(I) mRNA expression with large dose-related increases in collagenase protein expression being observed. TGF-beta 1-stimulated collagen-I lattice contraction was significantly inhibited following co-incubation with 100 ng/ml relaxin. Incremental doses of H2 relaxin had no significant effect on CTGF mRNA expression. CONCLUSIONS: The findings of this study suggest that the antifibrotic effects of relaxin involve down-regulation of fibroblast activity, increase in collagenase synthesis and restructuring of collagen-I lattices, which are consistent with its known physiological role of matrix remodelling. Although there appears to be an interaction between TGF-beta 1 and H2 relaxin, this does not appear to involve a reduction in CTGF mRNA expression. 相似文献
19.
20.