全文获取类型
收费全文 | 9179篇 |
免费 | 965篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 58篇 |
儿科学 | 455篇 |
妇产科学 | 264篇 |
基础医学 | 1382篇 |
口腔科学 | 125篇 |
临床医学 | 1214篇 |
内科学 | 1663篇 |
皮肤病学 | 246篇 |
神经病学 | 933篇 |
特种医学 | 174篇 |
外科学 | 825篇 |
综合类 | 229篇 |
一般理论 | 21篇 |
预防医学 | 1140篇 |
眼科学 | 163篇 |
药学 | 638篇 |
中国医学 | 10篇 |
肿瘤学 | 618篇 |
出版年
2024年 | 12篇 |
2023年 | 132篇 |
2022年 | 192篇 |
2021年 | 413篇 |
2020年 | 269篇 |
2019年 | 373篇 |
2018年 | 393篇 |
2017年 | 288篇 |
2016年 | 319篇 |
2015年 | 341篇 |
2014年 | 392篇 |
2013年 | 505篇 |
2012年 | 750篇 |
2011年 | 781篇 |
2010年 | 407篇 |
2009年 | 303篇 |
2008年 | 494篇 |
2007年 | 552篇 |
2006年 | 467篇 |
2005年 | 505篇 |
2004年 | 454篇 |
2003年 | 357篇 |
2002年 | 398篇 |
2001年 | 61篇 |
2000年 | 55篇 |
1999年 | 66篇 |
1998年 | 73篇 |
1997年 | 41篇 |
1996年 | 61篇 |
1995年 | 47篇 |
1994年 | 44篇 |
1993年 | 47篇 |
1992年 | 43篇 |
1991年 | 34篇 |
1990年 | 28篇 |
1989年 | 21篇 |
1987年 | 22篇 |
1986年 | 28篇 |
1985年 | 38篇 |
1984年 | 38篇 |
1983年 | 30篇 |
1982年 | 29篇 |
1981年 | 18篇 |
1980年 | 15篇 |
1979年 | 14篇 |
1978年 | 13篇 |
1975年 | 11篇 |
1973年 | 11篇 |
1972年 | 12篇 |
1962年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 309 毫秒
981.
982.
Renin secretion and synthesis in renal juxtaglomerular cells are controlled by short feed back loops involving angiotensin II and the intrarenal blood pressure. The operating mechanisms of these negative feed back regulators are widely unknown, except for the fact that both require calcium to exert their inhibitory action. We here show that in the absence of connexin40 (Cx40), which form gap junctions between juxtaglomerular and endothelial cells, the negative control of renin secretion and synthesis by angiotensin II and by intravasal pressure is abrogated, while the regulation by salt intake and beta-adrenergic stimulation is maintained. Renin secretion from Cx40-deficient kidneys or wild-type kidneys treated with the nonselective gap junction blocker 18alpha-glycyrrhetinic acid (10 micromol/L) resembles the situation in wild-type kidneys in the absence of extracellular calcium. This disturbed regulation is reflected by an enhanced plasma renin concentration despite an elevated blood pressure in Cx40-deficient mice. These findings indicate that Cx40 connexins and likely intercellular communication via Cx40-dependent gap junctions mediate the calcium-dependent inhibitor effects of angiotensin II and of intrarenal pressure on renin secretion and synthesis. Because Cx40 gap junctions are also formed between renin producing cells and endothelial cells our finding could provide additional information to suggest that the endothelium may be strongly involved in the control of the renin system. 相似文献
983.
984.
Bolton CE Broekhuizen R Ionescu AA Nixon LS Wouters EF Shale DJ Schols AM 《Thorax》2007,62(2):109-114
BACKGROUND: Pulmonary rehabilitation can improve the functional capacity, but has a variable effect on the low fat-free mass (FFM) in patients with chronic obstructive pulmonary disease. HYPOTHESIS: Pulmonary rehabilitation would not affect catabolic drives such as systemic inflammation and also protein breakdown. METHODS: Patients (n = 40) were studied at the start of an 8-week in-patient pulmonary rehabilitation programme, at the end of the programme and 4 weeks later. FFM and functional capacity (quadriceps strength, handgrip strength and peak workload) were assessed. Pseudouridine (PSU) urinary excretion (cellular protein breakdown) and inflammatory status were determined. Healthy participants had a single baseline assessment (n = 18). RESULTS: PSU, (IL)-6 and soluble tumour necrosis factor (sTNF)alpha R75 were increased in patients compared with healthy participants, whereas FFM and functional capacity were reduced (all p < 0.01). PSU was inversely related to both FFM and skeletal muscle function. FFM and functional parameters increased with rehabilitation, but PSU and inflammatory status were unaffected. The gain in FFM was lost 4 weeks after the completion of rehabilitation (p < 0.01). CONCLUSION: The anabolic effect of pulmonary rehabilitation improved FFM, but it did not reverse the increased protein breakdown or systemic inflammation. Thus, on cessation of pulmonary rehabilitation the FFM gains were lost owing to a loss of anabolic drive. 相似文献
985.
986.
987.
988.
Anne Marie Jelsig Thomas van Overeem Hansen Lene Bjerring Gede Niels Qvist Lise-Lotte Christensen Charlotte Kvist Lautrup Jane Hübertz Frederiksen Lone Sunde Lilian Bomme Ousager Ken Ljungmann Birgitte Bertelsen John Gásdal Karstensen 《Clinical genetics》2023,104(1):81-89
Peutz–Jeghers syndrome (PJS) is an autosomal dominant hereditary polyposis syndrome causing increased morbidity and mortality due to complications of polyposis and the development of cancer. STK11 is the only gene known to be associated with PJS, although in 10%–15% of patients fulfilling the diagnostic criteria no pathogenic variant (PV) is identified. The primary aim of this study was to identify the genetic etiology in all known PJS patients in Denmark and to estimate the risk of cancer, effect of surveillance and overall survival. We identified 56 patients (2–83 years old) with PJS. The detection rate of PVs was 96%, including three cases of mosaicism (6%). In two patients a variant was not detected. At the age of 40 years, the probabilities of cancer and death were 21% and 16%, respectively; at the age of 70 years these probabilities were 71% and 69%. Most cases of cancer (92%) were identified between the scheduled examinations in the surveillance program. These observations emphasize that PJS should be regarded as a general cancer predisposition syndrome, where improvement of clinical care is needed. 相似文献
989.
990.
The trunk neural crest and its early glial derivatives: a study of survival responses, developmental schedules and autocrine mechanisms 总被引:1,自引:0,他引:1
Woodhoo A Dean CH Droggiti A Mirsky R Jessen KR 《Molecular and cellular neurosciences》2004,25(1):30-41
Regulation of survival during gliogenesis from the trunk neural crest is poorly understood. Using adapted survival assays, we directly compared crest cells and the crest-derived precursor populations that generate satellite cells and Schwann cells. A range of factors that supports Schwann cells and glial precursors does not rescue crest, with the major exception of neuregulin-1 that rescues crest cells provided they contact the extracellular matrix. Autocrine survival appears earlier in developing satellite cells than Schwann cells. Satellite cells also show early expression of S100beta, BFABP and fibronectin and early survival responses to IGF-1, NT-3 and PDGF-BB that in developing Schwann cells are not seen until the precursor/Schwann cell transition. These experiments define novel differences between crest cells and early glia and show that entry to the glial lineage is an important point for regulation of survival responses. They show that survival mechanisms among PNS glia differ early in development and that satellite cell development runs ahead of schedule compared to Schwann cells in several significant features. 相似文献